液压传动和气压传动外文文献翻译、中英翻译、外文翻译
液压动力系统中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)原文：FEATURE-BASED COMPONENT MODELS FOR VIRTUALPROTOTYPING OF HYDRAULIC SYSTERMAbstract:This paper proposes a feature-based approach for the virtual prototyping of hydraulic systems. It presents a framework which allows the designer to develop a virtual hydraulic system prototype in a more intuitive manner, i.e. through assembly of virtual components with engineering data. The approach is based on identifying the data required for the development of the virtual prototypes, and separating the information into behaviour, structural, and product attributes. Suitable representations of these attributes are presented, and the framework for the feature-based virtual prototyping approach is established,based on the hierarchical structure of components in a hydraulic system. The proposed framework not only provides a precise model of the hydraulic prototype but also offers the possibility of designing variation classes of prototypes whose members are derived by changing certain virtual components with different features.Key words: Computer-aided engineering; Fluid power systems;Virtualprototyping1.IntroductionHydraulic system design can be viewed as a function-to-form transformation process that maps an explicit set of requirements into a physical realisable fluid power system. The process involves three main stages: the functional specification stage,the configuration design stage, and the prototyping stage.The format for the description of the design in each stage is different.The functional specification stage constitutes the initial design work. The objective is to map the design requirements. To achieve this, the design problems are specified Correspondence and offprint requests to: Dr S. C. Fok, Schoool of Mechanical and Production Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798. The designer must identify the performance attributes, which can include pressure, force, speed, and flowrate, with the required properties such as size, cost, safety and operating sequence. performance requirements for each attribute. In this stage, the design is abstracted in terms of the performance attributes with associated values.The objective of the configuration design stage is to synthesise a hydraulic circuit that performs the required functions conforming to the performance standards within defined constraints. A typical hydraulic system is made up of many subsystems. The smallest building block in a subsystem is the standard hydraulic component (such as valves, cylinders,pumps, etc.). Each type of standard component serves a specific elemental function. The design effort in the configuration design stage is fundamentally a search for a set of optimal arrangements of standard components (i.e. hydraulic circuit) to fulfil the functional requirements of the system. Based on this framework, the designers would normally decompose the overall system functions in terms of subfunctions. This will partition the search space and confine the search for smaller hydraulic subcircuits to perform the subfunctions.Computers are often used to support the configuration design process. For example, Kota and Lee devised a graph-based strategy to automate the configuration of hydraulic circuits. After the development of the hydraulic circuits, digital simulation tools are often used to study and evaluate these configurations. With these tools, designers can compare the behaviour of different circuits and also analyse the effects when subcircuits are combined. In the configuration design stage, the design is traditionally represented as a circuit drawing using standard icons to symbolise the type of standard component. This is a form of directed graph S(C,E) where the circuit S contains components C in the form of nodes with relations between components denoted by edges E.The prototyping stage is the verification phase of the system design process where the proposed hydraulic circuit from the configuration design stage isdeveloped and evaluated. Physical prototyping aims to build a physical prototype of the hydraulic system 666 S. C. Fok et al. using industrial available components. The process of physical prototyping involves the following: Search for appropriate standard components from different manufacturers. Pre-evaluation and selection of components based on individual component cost, size, and specification, and compatibility factors between components. Procurement and assembly of the selected components.Test and evaluate the physical prototype based on the overall system requirements. Use other components or redesign the circuit (or subcircuits)if necessary.Besides dynamics, the development of the physical prototype must take into consideration other factors including structure,cost, and weight. The dynamics data are used to confirm the fluid power system behaviour whereas the geometric information is used to examine the assembly properties. The development of the physical prototype will provide the actual performance,structure, and cost of the design.The main disadvantage of physical prototyping is that it is very tedious and time consuming to look for a set of suitable combinations of standard components from among so many manufacturers. Although the basic functions of the same types of standard component from different manufacturers do not differ, their dynamics, structural and cost characteristics may not be similar, because of design variation. Hence, for a given hydraulic circuit, different combinations of parts from differentmanufacturers can have implications on the resulting system,in terms of dynamics, structure, and cost. Value engineering can be used at this stage to improve the system design by improving the attributes at the component level. This includes maximizing the performance-to-cost ratio and minimising the size-to-performance ratio. Virtual prototyping can be viewed as a computer-aided design process, which employs modelling and simulating tools to address the broad issues of physical layout, operationalconcept, functional specifications, and dynamics analysis under various operating environments. The main advantage of virtual prototyping is that a hydraulic system prototype can be assembled, analysed, and modified using digital computers without the need for physical components, thus saving lead time and cost.The main requirement of a virtual hydraulic system prototype is to provide the same information as a physical prototype for the designer to make decisions.To achieve this, the virtual prototype must provide suitable and comprehensive representations of different data. Furthermore, transformation from one representation to another should proceed formally. Xiang et al. have reviewed the past and current computer-aided design and prototyping tools for fluid power systems. The work revealed that the current tools could not provide a completerepresentation of the design abstractions at the prototyping stage for design judgement. Most of the tools concentrate on the dynamics behaviour. Vital geometrical and product information that relates to the system prototype consideration and evaluation is frequently missing.To advance the development of computer-aided virtual prototyping tools for fluid power systems, there is a need to address the formal representations of different abstractions of behaviour,structural, and product data along with their integration. This paper focuses on these issues and proposes the formalism of a unified component model and the taxonomy based on the feature-based approach. In Section 2, we discuss the feature- based approach focusing on the key information and their representations required for hydraulic system prototyping. Section 3 presents a formalism of the feature-based model and structure for the development of virtual hydraulic system prototypes.The structure is illustrated with an example. Future work and conclusions are given in Section 4.2. Feature-Based ApproachFeatures can be defined as information sets that refer to aspects of attributes that can be used in reasoning about the design, engineering or manufacturing processes. The concept of using features to integrate CAD/CAPP/CAM is not new and there are many papers on the application of this approach in CIM. In all these applications, the feature model is regarded as the basis whereas design by features is the key for the integration. To develop a feature model, the relevant information concerning the design must be identified and grouped into sets based on the nature of the information. The relevant information should contain sufficient knowledge for activities such as design, analysis, test, documentation, inspection, and assembly, as well as support various administrative and logistic functions. Design by features is the process of building a model of the design using features as primitive entities. The feature model provides the standardisation of relevant data. Through the design by features approach, vital knowledge of the design will be generated and stored. Together, the feature model and the design by features approach will provide the essential information, which can be used, not only for the simultaneous consideration of many different concerns with the design, but also to interface the many activities in the design realisation process, including the life cycle support operations. The main drawback of the feature-based design approach is that the feature model should be properly defined . This can be difficult, as features are sets of knowledge that are application dependent. The organisation of the features can also be application specific. Non-trivial data-management problems could arise if the feature model is not properly defined. To avoid these problems, the type,representation and structure of the features should be resolved prior to using the feature-based design methodology. The main concern when developing afeature model is that it is application-specific. In the domain of virtual prototyping of hydraulic systems, the details of the constituent standard components must be able to be used to describe the overall system. The component features are bearers of knowledge about that part. To create a suitable feature model for hydraulic system design based on the assembly of standard components, the relevant information associated with various standard components must be identified and classified. This definition Feature-Based Component Models 667 of the component feature set can then be extended to encompass the subsystem feature set based on the hierarchical structure between the components in the subsystem. In the same manner, a hierarchical structure for the hydraulic system feature representation would evolve by considering the system as a hierarchy of subsystems.The necessary information required for a proper description of the virtual prototype must be no less than that derived by the designer from a physical prototype for decision making. These data should generally include the shape, weight, performance properties, cost, dimensions, functionality data, etc. Comparison with the physical prototyping process, the information required for each standard component could be separated into three distinct groups: behaviour attributes, structural attributes, and product attributes.2.1 Behaviour AttributesThe behaviour of a hydraulic component can be defined in terms of the dynamics characteristics used to satisfy the functional requirements. Consider a hydraulic cylinder connected to a load. Its function is to transmit a force from the stroke of the piston to the load. The maximum force it can transmit can be used to define the functionality and the behaviour requirements can be specified in terms of the desired load acceleration characteristics. Hence for a hydraulic component, behaviour attributes express functionality and can be reflected in the dynamics characteristics. The designer is responsible for the proper definition of the overall system behaviour characteristics in terms of the desired dynamics. A standard component will have its own behaviour and provide a specific plex functions that cannot be achieved by a single standard component are derived using a combination of components. Hence, the behaviour of the standard component will play an important role as the individual behaviours of components together with their arrangement can alter the overall system function .The behaviour of a standard component can be nonlinear and can be dependent on the operating conditions. When two components are combined, it is possible that their behaviours can interact and produce undesired or unintended characteristics. These unwanted behaviours are assumed to have been resolved during the configuration design stage. The hydraulic circuit used in theprototyping stage is assumed to be realisable and without any undesirable interacting behaviours. This means that the output behaviour of a component will provide the input to the subsequent component.The representation of behaviours for hydraulic systems has been widely investigated. These representations include transfer functions, state-space and bond graphs. Transfer functions (for single-input–single-output systems) and state-space equations (for multiple-input–multiple-output systems) are based on the approximation of the dynamics about a nominal operating condition. The power bond graph model is based on the causal effects that describe the energy transformations in the hydraulic system. This approach is appealing for hydraulic system analysis. The main disadvantage is that the derivation of the dynamics equation in a bond graph of a complicated fluid power system can become very tedious. As a result, recent work has concentrated on the used of artificial intelligence to represent the nonlinear mapping between the input and output data, which can be obtained via experimental work. These nonlinear mappings can be accomplished using artificial neural networks .It is quite natural for a hydraulic system designer to use input–output data to describe the behaviour of a hydraulic component. The configuration design of a hydraulic system is often achieved through steps of function decomposition. To design a hydraulic system, the designer often tries to decompose the functions and their requirements down to the component level.译文：基于原型液压系统特征的机构模型摘要：本文为原型液压系统的设计提出了一种基于特征的方法。
液压机外文翻译文献
液压机外文翻译文献(文档含中英文对照即英文原文和中文翻译)原文：The Analysis of Cavitation Problems in the Axial Piston Pumpshu WangEaton Corporation,14615 Lone Oak Road,Eden Prairie, MN 55344This paper discusses and analyzes the control volume of a piston bore constrained by the valve plate in axial piston pumps. The vacuum within the piston bore caused by the rise volume needs to be compensated by the flow; otherwise, the low pressure may cause the cavitations and aerations. In the research, the valve plate geometry can be optimized by some analytical limitations to prevent the piston pressure below the vapor pressure. The limitations provide the design guide of the timings andoverlap areas between valve plate ports and barrel kidneys to consider the cavitations and aerations. _DOI: 10.1115/1.4002058_ Keywords: cavitation , optimization, valve plate, pressure undershoots1 IntroductionIn hydrostatic machines, cavitations mean that cavities or bubbles form in the hydraulic liquid at the low pressure and collapse at the high pressure region, which causes noise, vibration, and less efficiency.Cavitations are undesirable in the pump since the shock waves formed by collapsed may be strong enough to damage components. The hydraulic fluid will vaporize when its pressure becomes too low or when the temperature is too high. In practice, a number of approaches are mostly used to deal with the problems: (1) raise the liquid level in the tank, (2) pressurize the tank, (3) booster the inlet pressure of the pump,(4) lower the pumping fluid temperature, and (5) design deliberately the pump itself.Many research efforts have been made on cavitation phenomena in hydraulic machine designs. The cavitation is classified into two types in piston pumps: trapping phenomenon related one (which can be prevented by the proper design of the valve plate)and the one observed on the layers after the contraction or enlargement of flow passages (caused by rotating group designs) in Ref. (1). The relationship between the cavitation and the measured cylinder pressure is addressed in this study. Edge and Darling (2) reported an experimental study of the cylinder pressure within an axial piston pump. The inclusion of fluid momentum effects and cavitations within the cylinder bore are predicted at both highspeed and high load conditions. Another study in Ref. (3) provides an overview of hydraulic fluid impacting on the inlet condition and cavitation potential. It indicates thatphysical properties (such as vapor pressure, viscosity, density, and bulk modulus) are vital to properly evaluate the effects on lubrication and cavitation. A homogeneous cavitation model based on the thermodynamic properties of the liquid and steam is used to understand the basic physical phenomena of mass flow reduction and wave motion influences in the hydraulic tools and injection systems (4). Dular et al. (5, 6) developed an expert system for monitoring and control of cavitations in hydraulic machines and investigated the possibility of cavitation erosion by using the computational fluid dynamics (CFD) tools. The erosion effects of cavitations have been measured and validated by a simple single hydrofoil configuration in a cavitation tunnel. It is assumed that the severe erosion is often due to the repeated collapse of the traveling vortex generated by a leading edge cavity in Ref. (7). Then, the cavitation erosion intensity may be scaled by a simple set of flow parameters: theupstream velocity, the Strouhal number, the cavity length, and the pressure. A new cavitation erosion device, called vortex cavitation generator, is introduced to comparatively study various erosion situations (8).More previous research has been concentrated on the valve plate designs, piston, and pump pressure dynamics that can be associated with cavitations in axial piston pumps. The control volume approach and instantaneous flows (leakage) are profoundly studied in Ref. [9]. Berta et al. [10] used the finite volume concept to develop a mathematical model in which the effects of port plate relief grooves have been modeled and the gaseous cavitation is considered in a simplified manner. An improved model is proposed in Ref.[11] and validated by experimental results. The model may analyze the cylinder pressure and flow ripples influenced by port plate and relief groove design. Manring comparedprincipal advantages of various valve plate slots (i.e., theslots with constant, linearly varying, and quadratic varyingareas) in axial piston pumps [12]. Four different numericalmodels are focused on the characteristics of hydraulic fluid,and cavitations are taken into account in different ways toassist the reduction in flow oscillations [13].The experiences of piston pump developments show thatthe optimization of the cavitations/aerations shall includethe following issues: occurring cavitation and air release,pump acoustics caused by the induced noises, maximal amplitudes of pressure fluctuations, rotational torque progression, etc. However, the aim of this study is to modifythe valve plate design to prevent cavitation erosions causedby collapsing steam or air bubbles on the walls of axial pump components. In contrast to literature studies, the researchfocuses on the development of analytical relationshipbetween the valve plate geometrics and cavitations. The optimization method is applied to analyze the pressure undershoots compared with the saturated vapor pressurewithin the piston bore.The appropriate design of instantaneous flow areas betweenthe valve plate and barrel kidney can be decided consequently.2 The Axial Piston Pump and Valve PlateThe typical schematic of the design of the axis piston pumpis shown in Fig. 1. The shaft offset e is designed in this caseto generate stroking containment moments for reducingcost purposes.The variation between the pivot center of the slipper andswash rotating center is shown as a. The swash angle αis the variable that determines the amount of fluid pumped pershaft revolution. In Fig. 1, the n th piston-slipper assembly is located at the angle of nθ. The displacement of the n thpiston-slipper assembly along the x-axis can be written asx n = R tan （α）sin （n θ）+ a sec （α） + e tan (α) (1) where R is the pitch radius of the rotating group. Then, the instantaneous velocity of the n th piston is x˙n = R 2sec ()αsin （n θ）α+ R tan （α）cos （n θ）ω+ R 2sec ()αsin （α）α + e 2sec ()αα (2) where the shaft rotating speed of the pump is ω=d n θ / dt .The valve plate is the most significant device to constraint flow in piston pumps. The geometry of intake/discharge ports on the valve plate and its instantaneous relative positions with respect to barrel kidneys are usually referred to the valve plate timing. The ports of the valve plate overlap with each barrel kidneys to construct a flow area or passage, which confines the fluid dynamics of the pump. In Fig. 2, the timing angles of the discharge and intake ports on the valve plate are listed as (,)T i d δ and (,)B i d δ. The opening angle of the barrel kidney is referred to as ϕ. In some designs, there exists asimultaneous overlap between the barrel kidney and intake/discharge slots at the locations of the top deadcenter (TDC) or bottom dead center (BDC) on the valve plate on which the overlap area appears together referred to as “cross-porting” in the pump design engineering. The cross-porting communicates the discharge and intake ports, which may usually lower the volumetric efficiency. The trapped-volume design is compared with the design of the cross-porting, and it can achieve better efficiency 14]. However, the cross-porting isFig. 1 The typical axis piston pump commonly used to benefit the noise issue and pump stability in practice.3 The Control Volume of a Piston BoreIn the piston pump, the fluid within one piston is embraced by the piston bore, cylinder barrel, slipper,valve plate, and swash plate shown in Fig. 3. There exist some types of slip flow by virtue of relative Fig. 2 Timing of the valve plate motions and clearances between thos e components. Within the control volume of each piston bore, the instantaneous mass is calculated asn M = ρn V (3) where ρ and n V are the instantaneous density and volume such that themass time rate of change can be given asFig. 3 The control volume of the piston boren n n dM dV d V dt dt dtρρ=+ (4)where d n V is the varying of the volume.Based on the conservation equation, the mass rate in the control volume isn n dM q dtρ= (5) where n q is the instantaneous flow rate in and out of onepiston. From the definition of the bulk modulus,n dP d dt dtρρβ= (6) where Pn is the instantaneous pressure within the piston bore. Substituting Eqs. (5) and (6) into Eq. (4) yields(?)n n n n n ndP q dV d V w d βθθ=- (7) where the shaft speed of the pump is n d dt θω=. The instantaneous volume of one piston bore can be calculated by using Eq. (1) asn V = 0V + P A [R tan （α）sin （n θ）+ a sec （α） + e tan (α) ](8) where P A is the piston sectional area and 0V is the volume of each piston, which has zero displacement along the x-axis (when n θ=0, π).The volume rate of change can be calculated at thecertain swash angle, i.e., α =0, such thattan cos n p n ndV A R d αθθ=（）（） (9) in which it is noted that the piston bore volume increases or decreases with respect to the rotating angle of n θ. Substituting Eqs. (8) and (9) into Eq. (7) yields0[tan()cos()] [tan sin sec tan() ]n P n n n p n q A R dP d V A R a e βαθωθαθαα-=-++（）（）（）(10)4 Optimal DesignsTo find the extrema of pressure overshoots and undershoots in the control volume of piston bores, the optimization method can be used in Eq. (10). In a nonlinear function, reaching global maxima and minima is usually the goal of optimization. If the function is continuous on a closed interval, global maxima and minima exist. Furthermore, the global maximum (or minimum) either must be a local maximum (or minimum) in the interior of the domain or must lie on the boundary of the domain. So, the method of finding a global maximum (or minimum) is to detect all the local maxima (or minima) in the interior, evaluate themaxima (or minima) points on the boundary, and select the biggest (or smallest) one. Local maximum or local minimum can be searched by using the first derivative test that the potential extrema of a function f( · ), with derivative ()f ', can solve the equation at the critical points of ()f '=0 [15]. The pressure of control volumes in the piston bore may be found as either a minimum or maximum value as dP/ dt=0. Thus, letting the left side of Eq. (10) be equal to zero yields tan()cos()0n p n q A R ωαθ-= (11) In a piston bore, the quantity of n q offsets the volume varying and then decreases the overshoots and undershoots of the piston pressure. In this study, the most interesting are undershoots of the pressure, which may fall below the vapor pressure or gas desorption pressure to cause cavitations. The term oftan()cos()p n A R ωαθ in Eq. (11) has the positive value in the range of intake ports (22ππθ-≤≤), shown in Fig. 2, which means that the piston volume arises. Therefore, the piston needs the sufficient flow in; otherwise, the pressure may drop.In the piston, the flow of n q may get through in a few scenarios shown in Fig. 3: (I) the clearance between the valve plate and cylinder barrel, (II) the clearance between the cylinder bore and piston, (III) theclearance between the piston and slipper, (IV) the clearance between the slipper and swash plate, and (V) theoverlapping area between the barrel kidney and valve plate ports. As pumps operate stably, the flows in the as laminar flows, which can be calculated as [16]312IV k k Ln i I k h q p L ωμ==∑ (12)where k h is the height of the clearance, k L is the passagelength,scenarios I –IV mostly have low Reynolds numbers and can be regardedk ω is the width of the clearance (note that in the scenario II,k ω =2π· r, in which r is the piston radius), and p is the pressure drop defined in the intake ports as p =c p -n p (13) where c p is the case pressure of the pump. The fluid films through the above clearances were extensively investigated in previous research. The effects of the main related dimensions of pump and the operating conditions on the film are numerically clarified in Refs. [17,18]. The dynamic behavior of slipper pads and the clearance between the slipper and swash plate can be referred to Refs. [19,20]. Manring et al. [21,22]investigated the flow rate and load carrying capacity of the slipper bearing in theoretical and experimental methods under different deformation conditions. A simulation tool called CASPAR is used to estimate the nonisothermal gap flow between the cylinder barrel and the valve plate by Huang and Ivantysynova [23]. The simulation program also considers the surface deformations to predict gap heights, frictions, etc., between the piston and barrel and between the swash plate and slipper. All these clearance geometrics in Eq. (12) are nonlinear and operation based, which is a complicated issue. In this study, the experimental measurements of the gap flows are preferred. If it is not possible, the worst cases of the geometrics or tolerances with empirical adjustments may be used to consider the cavitation issue, i.e., minimum gap flows.For scenario V, the flow is mostly in high velocity and can be described by using the turbulent orifice equation as((Tn d i d d q c A c A θθ= (14) where Pi and Pd are the intake and discharge pressure of the pump and ()i A θ and ()d A θ are the instantaneousoverlap area between barrel kidneys and inlet/discharge ports of the valve plate individually.The areas are nonlinear functions of the rotating angle, which is defined by the geometrics of the barrel kidney, valve plate ports, silencing grooves, decompression holes, and so forth. Combining Eqs. (11) –(14), the area can beobtained as3()K IV A θ==(15)where ()A θ is the total overlap area of ()A θ=()()i d A A θλθ+, andλis defined as=In the piston bore, the pressure variesfrom low to high while passing over the intake and discharge ports of the valve plates. It is possible that the instantaneous pressure achieves extremely low values during the intakearea( 22ππθ-≤≤ shown in Fig. 2) that may be located below the vapor pressure vp p , i.e., n vp p p ≤;then cavitations canhappen. To prevent the phenomena, the total overlap area of ()A θmight be designed to be satisfied with30()K IV A θ=≥(16)where 0()A θ is the minimum area of 0()A θ=0()()i d A A θλθ+and0λis a constant that is0λ=evaporates into a gaseous form. The vapor pressure of any substance increases nonlinearly with temperature according to the Clausius –Clapeyron relation. With the incremental increase in temperature, the vapor pressure becomes sufficient to overcome particle attraction and make the liquid form bubbles inside the substance. For pure components, the vapor pressure can be determined by the temperature using the Antoine equation as /()10A B C T --, where T is the temperature, and A, B, and C are constants [24]. As a piston traverse the intake port, the pressure varies dependent on the cosine function in Eq. (10). It is noted that there are some typical positions of the piston with respect tothe intake port, the beginning and ending of overlap, i.e., TDC and BDC (/2,/2θππ=- ) and the zero displacement position (θ =0). The two situations will be discussed as follows: (1) When /2,/2θππ=-, it is not always necessary to maintain the overlap area of 0()A θ because slip flows may provide filling up for the vacuum. From Eq. (16), letting 0()A θ=0,the timing angles at the TDC and BDC may be designed as31cos ()tan()122IV c vpk k i I P k p p h A r L ωϕδωαμ--≤+∑ (17) in which the open angle of the barrel kidney is . There is no cross-porting flow with the timing in the intake port.(2) When θ =0, the function of cos θ has the maximum value, which can provide another limitation of the overlap area to prevent the low pressure undershoots suchthat 30(0)K IV A =≥ (18)where 0(0)A is the minimum overlap area of 0(0)(0)i A A .To prevent the low piston pressure building bubbles, the vapor pressure is considered as the lower limitation for the pressure settings in Eq. (16). The overall of overlap areas then can be derived to have a design limitation. The limitation is determined by the leakage conditions, vapor pressure, rotating speed, etc. It indicates that the higher the pumping speed, the more severe cavitation may happen, and then the designs need more overlap area to let flow in the piston bore. On the other side, the low vapor pressure of the hydraulic fluid is preferred to reduce the opportunities to reach the cavitation conditions. As a result, only the vapor pressure of the pure fluid is considered in Eqs. (16)–(18). In fact, air release starts in the higher pressure than the pure cavitation process mainly in turbulent shear layers, which occur in scenario V. Therefore, the vapor pressure might be adjusted to design the overlap area by Eq. (16) if there exists substantial trapped and dissolved air in the fluid. The laminar leakages through the clearances aforementioned are a tradeoff in the design. It is demonstrated that the more leakage from the pump case to piston may relieve cavitation problems.However, the more leakage may degrade the pump efficiency in the discharge ports. In some design cases, the maximum timing angles can be determined by Eq. (17)to not have both simultaneous overlapping and highly low pressure at the TDC and BDC. While the piston rotates to have the zero displacement, the minimum overlap area can be determined by Eq. 18 , which may assist the piston not to have the large pressure undershoots during flow intake.6 Conclusions The valve plate design is a critical issue in addressing thecavitation or aeration phenomena in the piston pump. This study uses the control volume method to analyze the flow, pressure, and leakages within one piston bore related to the valve plate timings. If the overlap area developed by barrel kidneys and valve plate ports is not properly designed, no sufficient flow replenishes the rise volume by the rotating movement. Therefore, the piston pressure may drop below the saturated vapor pressure of the liquid and air ingress to form the vapor bubbles. To control the damaging cavitations, the optimization approach is used to detect the lowest pressure constricted by valve plate timings. The analytical limitation of the overlap area needs to be satisfied to remain the pressure to not have large undershoots so that the system can be largely enhanced on cavitation/aeration issues. In this study, the dynamics of the piston control volume is developed by using several assumptions such as constant discharge coefficients and laminar leakages. The discharge coefficient is practically nonlinear based on the geometrics, flow number, etc. Leakage clearances of the control volume may not keep the constant height and width as well in practice due to vibrations and dynamical ripples. All these issues are complicated and very empirical and need further consideration in the future. The results presented in this paper can be more accurate in estimating the cavitations with these extensive studies. Nomenclature0(),()A A θθ= the total overlap area between valve plate ports and barrel kidneys 2()mm Ap = piston section area 2()mm A, B, C= constants A= offset between the piston-slipper joint and surface of the swash plate 2()mmd C = orifice discharge coefficiente= offset between the swash plate pivot and the shaft centerline of the pump 2()mmk h = the height of the clearance 2()mmk L = the passage length of the clearance 2()mm M= mass of the fluid within a single piston (kg) N= number of pistons n = piston and slipper counter,p p = fluid pressure and pressure drop (bar) Pc= the case pressure of the pump (bar) Pd= pump discharge pressure (bar) Pi = pump intake pressure (bar) Pn = fluid pressure within the nth piston bore (bar) Pvp = the vapor pressure of the hydraulic fluid(bar) qn, qLn, qTn = the instantaneous flow rate of each piston (l/min) R = piston pitch radius 2()mmr = piston radius (mm )t =time (s )V = volume 3()mmwk = the width of the clearance (mm )x ,x˙= piston displacement and velocity along the shaft axis (m, m/s )x y z --=Cartesian coordinates with an origin on the shaft centerlinex y z '''--= Cartesian coordinates with an origin on swash plate pivot,αα=swash plate angle and velocity (rad, rad/s )β= fluid bulk modulus (bar ),B T δδ= timing angle of valve plates at the BDC and TDC (rad ) ϕ = the open angle of the barrel kidney (rad )ρ= fluid density (kg /m3),θω = angular position and velocity of the rotating kit (rad, rad/s )μ =absolute viscosity (Cp ),λλ=coefficients related to the pressure drop翻译：在轴向柱塞泵气蚀问题的分析本论文讨论和分析了一个柱塞孔与配流盘限制在轴向柱塞泵的控制量设计。
液压系统液压传动和气压传动毕业论文中英文资料对照外文翻译文献综述
中英文资料对照外文翻译文献综述液压系统液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质，以水压机的形式将其应用于工业上，诞生了世界上第一台水压机。
1905年将工作介质水改为油，又进一步得到改善。
第一次世界大战(1914-1918)后液压传动广泛应用，特别是1920年以后，发展更为迅速。
液压元件大约在 19 世纪末 20 世纪初的20年间，才开始进入正规的工业生产阶段。
1925 年维克斯(F.Vikers)发明了压力平衡式叶片泵,为近代液压元件工业或液压传动的逐步建立奠定了基础。
20 世纪初康斯坦丁•尼斯克(G•Constantimsco)对能量波动传递所进行的理论及实际研究;1910年对液力传动(液力联轴节、液力变矩器等)方面的贡献，使这两方面领域得到了发展。
第二次世界大战(1941-1945)期间,在美国机床中有30%应用了液压传动。
应该指出,日本液压传动的发展较欧美等国家晚了近 20 多年。
在 1955 年前后 , 日本迅速发展液压传动,1956 年成立了“液压工业会”。
近20～30 年间，日本液压传动发展之快，居世界领先地位。
液压传动有许多突出的优点，因此它的应用非常广泛，如一般工业用的塑料加工机械、压力机械、机床等；行走机械中的工程机械、建筑机械、农业机械、汽车等；钢铁工业用的冶金机械、提升装置、轧辊调整装置等；土木水利工程用的防洪闸门及堤坝装置、河床升降装置、桥梁操纵机构等；发电厂涡轮机调速装置、核发电厂等等；船舶用的甲板起重机械（绞车）、船头门、舱壁阀、船尾推进器等；特殊技术用的巨型天线控制装置、测量浮标、升降旋转舞台等；军事工业用的火炮操纵装置、船舶减摇装置、飞行器仿真、飞机起落架的收放装置和方向舵控制装置等。
一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助元件和液压油。
液压传动系统外文文献翻译、中英文翻译、外文翻译
中国地质大学长城学院本科毕业设计外文资料翻译系别工程技术系专业机械设计制造及其自动化学生姓名彭江鹤学号 05211534指导教师王泽河职称教授2015 年 5 月 4 日液压传动系统作者：Hopmans, ArthurH.摘要液压传动是由液压泵、液压控制阀、液压执行元件和液压辅件组成的液压系统。
液压泵把机械能转换成液体的压力能，液压控制阀和液压辅件控制液压介质的压力、流量和流动方向，将液压泵输出的压力能传给执行元件，执行元件将液体压力能转换为机械能，以完成要求的动作。
关键词：液压传动；气压传动；传动系统；许多液压传动先前已经设计出允许操作者无限变化输出的变速器，或甚至逆转的传动装置的输出作为相对于输入。
通常情况下，这已经通过使用一个旋转斜盘是要么由操作者手动或操作液压动机来改变通过旋转泵头部具有轴向移动的活塞流动的液压流体的。
液压流体从泵头活塞的流动，依次转动的马达头通过激励相应的一组活塞在其中违背一固定凸轮的，因此，旋转安装在电动机头的输出轴。
通常情况下，在现有技术的变速器已被被设置有各种功能，例如齿轮减速，刹车设定装置等。
不幸的是，这些功能通常是提供外部发送的和显著增加整个装置的体积和质量。
申请人确定，这是很期望具有其中基本上所有的这些需要或希望的功能，可以在内部提供的发送，同时还产生一个非常有效的和非常有效的传输的综合传输。
特别是，这种类型的变速器上经常使用的设备，如“零转动半径”剪草机之类的其中一个潜在的危险情况面对操作者，旁观者和设备本身，如果设备我们允许继续被推进应的操作者释放控制，由于当操作者无意中从装置抛出或变得受伤。
因此，“故障自动刹车”机制经常被设置为传输自动地返回到中立配置在这种情况下，使得该装置不会继续供电，如果控制被释放。
先前传输这种类型的一般依靠某种外部设备，比如其目的是为了在操作者控制轴返回到中立位置应操作者释放所述轴的反操作偏压弹簧。
这种类型的外部设备，可以容易地由用户或篡改损坏。
液压机械与液压泵外文翻译文献
液压机械与液压泵外文翻译文献液压机械与液压泵外文翻译文献(文档含中英文对照即英文原文和中文翻译)Hydraulic machinery and pumpHydraulic machinery are machines and tools which use fluid power to do work. Heavy equipment is a common example.In this type of machine, high-pressure liquid - called hydraulic fluid - is transmitted throughout the machine to various hydraulic motors and hydraulic cylinders. The fluid is controlled directly or automatically by control valves and distributed through hoses and tubes.The popularity of hydraulic machinery is due to the very large amount ofpower that can be transferred through small tubes and flexible hoses, and the high power density and wide array of actuators that can make use of this power.Hydraulic machinery is operated by the use of hydraulics, where a liquid is the powering medium. Pneumatics, on the other side, is based on the use of a gas as the medium for power transmission, generation and control.Hydraulic circuitsFor the hydraulic fluid to do work, it must flow to the actuator and or motors, then return to a reservoir.The fluid is then filtered and re-pumped. The path taken by hydraulic fluid is called a hydraulic circuit of which there are several types. Open center circuits use pumps which supply a continuous flow. The flow is returned to tank through the control valve's open center; that is, when the control valve is centered, it provides an open return path to tank and the fluid is not pumped to a high pressure. Otherwise, if the control valve is actuated it routes fluid to and from an actuator and tank. The fluid's pressure will rise to meet any resistance, since the pump has a constant output. If the pressure rises too high, fluid returns to tank through a pressure relief valve.Hydraulic pumps supply fluid to the components in the system. Pressure in the system develops in reaction to the load. Hence,a pump rated for 5,000 psi is capable of maintaining flow against a load of 5,000 psi.Pumps have a power density about ten times greater than an electric motor (by volume). They are powered by an electric motor or an engine, connected through gears, belts, or a flexible elastomeric coupling to reduce vibration.Common types of hydraulic pumps to hydraulic machinery applications are;Gear pump: cheap, durable, simple. Less efficient, because they are constant displacement, and mainly suitable for pressures below 20 MPa (3000 psi).Vane pump: cheap and simple, reliable (especially in g-rotor form). Good for higher-flow low-pressure output.Axial piston pump: many designed with a variable displacement mechanism, to vary output flow for automatic control of pressure. There are various axial piston pump designs, including swashplate and checkball. The most common is the swashplate pump.Radial piston pump: A pump that is normally used for very high pressure at small flows.Piston pumps are more expensive than gear or vane pumps, but provide longer life operating at higher pressure, with difficult fluids and longer continuous duty cycles. Pistonpumps make up one half of a hydrostatic transmission. Control valvesDirectional control valves route the fluid to the desired actuator. They usually consist of a spool inside a cast iron or steel housing.Directional control valves are usually designed to be stackable, with one valve for each hydraulic cylinder, and one fluid input supplying all the valves in the stack.The spool position may be actuated by mechanical levers, hydraulic pilot pressure, or solenoids which push the spool left or right.The main valve block is usually a stack of off the shelf directional control valves chosen by flow capacity and performance. Some valves are designed to be proportional (flow rate proportional to valve position), while others may be simply on-off. The control valve is one of the most expensive and sensitive parts of a hydraulic circuit.Pressure relief valves are used in several places in hydraulic machinery; on the return circuit to maintain a small amount of pressure for brakes, pilot lines, etc... On hydraulic cylinders, to prevent overloading and hydraulic line rupture. On the hydraulic reservoir, to maintain a small positive pressurewhich excludes moisture and contamination.Pressure reducing valves reduce the supply pressure as needed for various circuits.Check valves are one-way valves, allowing an accumulator to charge and maintain its pressure after the machine is turned off, for example.Counterbalance valves are in fact a special type of pilot controlled check valve. Whereas the check valve is open or closed, the counterbalance valve acts a bit like a pilot controlled flow control.Hydraulic pump typesGear pumpsGear pumps (with external teeth) (fixed displacement) are simple and economical pumps. The swept volume or displacement of gear pumps for hydraulics will be between about 1 cm3(0.001 litre) and 200 cm3(0.2 litre). These pumps create pressure through the meshing of the gear teeth, which forces fluid around the gears to pressurize the outlet side. Some gear pumps can be quite noisy, compared to other types, but modern gear pumps are highly reliable and much quieter than older models.Rotary vane pumpsRotary vane pumps (fixed and simple adjustable displacement) have higher efficiencies than gear pumps, but are also used for mid pressures up to 180 bars in general. Some types of vane pumps can change the centre of the vane body, so that a simple adjustable pump is obtained. These adjustable vane pumps are in general constant pressure or constant power pumps: the displacement is increased until the required pressure or power is reached and subsequently the displacement or swept volume is decreased until an equilibrium is reached.Screw pumpsScrew pumps (fixed displacement) are a double Archimedes' screw, but closed. This means that two screws are used in one body. The pumps are used for high flows and relatively low pressure (max 100 bar). They were used on board ships where the constant pressure hydraulic system was going through the whole ship, especially for the control of ball valves, but also for the steering gear and help drive systems. The advantage of the screw pumps is the low sound level of these pumps; the efficiency is not that high.Bent axis pumpsBent axis pumps, axial piston pumps and motors using the bent axis principle, fixed or adjustable displacement, exists in two different basic designs. The Thoma-principle (engineer Hans Thoma, Germany, patent 1935) with max 25 degrees angle and the Wahlmark-principle (GunnarAxel Wahlmark, patent 1960) with spherical-shaped pistons in one piece with the piston rod, piston rings, and maximum 40 degrees between the driveshaft centerline and pistons (V olvo Hydraulics Co.). These have the best efficiency of all pumps. Although in general the largest displacements are approximately one litre per revolution, if necessary a two-liter swept volume pump can be built. Often variable-displacement pumps are used, so that the oil flow can be adjusted carefully. These pumps can in general work with a working pressure of up to 350–420 bars in continuous work.Axial piston pumps swashplate principleAxial piston pumps using the swashplate principle (fixed and adjustable displacement) have a quality that is almost the same as the bent axis model. They have the advantage of being more compact in design. The pumps are easier and more economical to manufacture; the disadvantage is that they are more sensitive to oil contamination.Radial piston pumpsRadial piston pumps (fixed displacement) are used especially for high pressure and relatively small flows. Pressures of up to 650 bar are normal. In fact variable displacement is not possible, but sometimes the pump is designed in such a way that the plungers can be switched off one by one, so that a sort of variable displacement pump is obtained.Peristaltic pumpsPeristaltic pumps are not generally used for high pressures.Pumps for open and closed systemsMost pumps are working in open systems. The pump draws oil from a reservoir at atmospheric pressure. It is very important that there is no cavitation at the suction side of the pump. For this reason the connection of the suction side of the pump is larger in diameter than the connection of the pressure side. In case of the use of multi-pump assemblies, the suction connection of the pump is often combined. It is preferred to have free flow to the pump (pressure at inlet of pump at least 0.8 bars). The body of the pump is often in open connection with the suction side of the pump.In case of a closed system, both sides of the pump can be at high pressure. The reservoir is often pressurized with 6-20 bars boost pressure. For closed loop systems, normally axial piston pumps are used. Because both sides are pressurized, the body of the pump needs a separate leakage connection.Multi pump assemblyIn a hydraulic installation, one pump can serve more cylinders and motors. The problem however is that in that case a constant pressure system is required and the system always needs the full power. It is more economic to give each cylinder and motor its own pump. In that case multi pump assemblies can be used. Gearpumps can often be obtained as multi pumps.The different chambers (sometimes of different size) are mounted in one body or built together. Also vane pumps can often be obtained as a multi pump. Gerotor pumps are often supplied as multi pumps. Screw pumps can be built together with a gear pump or a vane pump. Axial piston swashplate pumps can be built together with a second pump of the same or smaller size, or can be built together with one or more gear pumps or vane pumps (depending on the supplier). Axial plunger pumps of the bent axis design can not be built together with other pumps.翻译：液压机械及泵液压机械是机械和工具,它使用流体的力量去做的工作。
液压传动和传动油外文文献翻译、中英文翻译、外文翻译
fluid driven and transmission oilFormer statement fluid transmission is including gas (pressure) transmission and liquid transmission, hydraulic transmission into liquid transmission, hydraulic transmission and fluid Nien transmission. Hydraulic transmission based on the interior market, the pressure to be able to impart impetus liquid; Hydraulic transmission based on Oula equation to the liquid changes to the short wheel drive transmission; For Newton, Nien transmission fluid friction law, the sticky liquid to impart dynamism to.Hydraulic transmission is the basic hydraulic components and hydraulic Bianjuqi coupled device. Hydraulic coupled devices is a fundamental component of a number of radial plane leaves, a work of the pump and turbine round. Hydraulic transmission oil in the work of the cycle of high-speed mobile transmission power, oil pumps round her so involved with the campaign because centrifugal force role do centrifuge campaign from pumps round (and imported axis) and to absorb mechanical energy into moment of momentum (mVR) incremental, high-speed Yeliu round water from the pump to the heart to do turbine flow release moment of momentum. promote turbine (and export axis) rotation, work-driven plane (and load) homework. Hydraulic Bianjuqi basic components are pumps round, and the turbine-round, they are a space (bending) leaves work round by the work of a relevant order. Hydraulic transmission oil pumps were working round the turbine mix for incremental Ye Liu was moment of momentum, after transfer-round water turbine Yeliu direction after the release of moment of momentum (kinetic energy) to promote the work of the turbine-driven rotary rush.My hydraulic components in the development of faster, 2003 hydraulic coupled devices produced about 70,000 National Taiwan. Widely used for Daishishusongji, rail carriers, ball mill, air-compressors, compressors, pumps and fuel pumps, and other equipment, transmission, improve transmission quality and energy conservation. My hydrauliccoupled with the current maximum output rotational speed for 6500r/min, minimum power to 0.3kW, the maximum power to 7100kW. Hydraulic trend is coupled with a high rotational speed and power.International hydraulic coupled device products to the most famous German Fuk under special company, according to information that has reached 20000r/min rotational speed and power to 55000kW products, which are still visible in considerable gap. Of course, the power of the big oil hydraulic components for hydraulic transmission requirements higher. Hydraulic Bianjuqi mainly for engineering machinery, machinery and diesel oil. Hydraulic Bianjuqi main internal combustion engine with matching applications, the scope of its rotational speed in 2000~3000r/min. Mechanical engineering applications more, the greatest power 700HP about output about 70,000 Taiwan. Oil machinery applications less power to 1500HP. Diesel applications less power up 3000HP.Nien transmission fluid is a liquid transmission doors emerging disciplines in the country are still at an infancy stage. Because liquid Nien transmission products (such as fluid mechanics using Nien) and hydraulic transmission products (such as governor-hydraulic coupled device) Notwithstanding the different nature, but because of similar performance and the same purposes (governor energy), in a number of technical activities (such as the formulation of development plans, standards, technology management, orders, and other activities) are regarded as the same type, with the hydraulic industry commonalities, it is another chapter on the work of its product mix and transmission oil.First, the performance characteristics of the oil and hydraulic transmission hydraulic transmission oil development not only as a transmission medium for work, but also to provide lubrication bearings and gear while the carrier is further bad fever, heat away. Hydraulic transmission oil is a complex and require specialized research topics, which is directly related to the reliability of hydraulic components,transmission efficiency and service life. Should arouse the attention of extensive in-depth study.Hydraulic transmission oil should meet the following requirements : 1、A suitable low-viscosity liquid viscosity, liquid indicate friction within small, mobile resistance small loss may reduce hydraulic components hydraulic losses; But lubricant sealed perspective, the viscosity can not be too low. Provide lubrication and therefore should meet the requirements of sealed premise as a low-viscosity liquid to improve hydraulic components transmission efficiency. Wen Xing Nien also called liquid than for the high-temperature or low-temperature, and still maintain an effective lubricant sealed.2、A greater emphasis on the hydraulic components for the moment and the power transmission and liquid working for the re-direct, it is liquid-degrees the higher the better.3、The performance can have a stable bubble, aging and sedimentation.4、Suanzhi sealed pieces to be neutral to low, and a good compatibility, not dwell inflation, not dissolved, the non-corrosive metal.5、A higher flash point and lower congeal point hydraulic components work Youwen change significantly, sometimes up to 160 degrees, and therefore require flash point higher than 180 degrees, and congeal point lower than -20 degrees, low-temperature environment for the benefit of the start-up of hydraulic components.6、A good lubricant performance liquid sufficient greasiness to the good parts in the surface material, a good lubricant.At present, and hydraulic transmission applications work more liquid types, among all oil-based products, has used the water or other liquid Nanran (coal mine explosion and fire in defense applications). Domestic hydraulic components commonly used 6th hydraulic transmission oil (also useful 8th hydraulic transmission oil), and sometimes to 22 turbine fuel substitution.Diesel oil is dedicated to the life of not less than 2,000 hours andfor the initial operation of new equipment installed oil after 100 hours and 500 hours of the first, second formula, can still be used after the filter.Is one of the following situations, the need to replace the new oil : Water content greater than 0.2%; 50 degrees in the new oil viscosity higher than 6% mounted; Mechanical impurities (benzene Burong objects) to reach 0.2%; A high lipid intake or Suanzhi; Excessive bubble effects transmission power. More articles on the diesel-hydraulic transmission oil outside the oil will definitely reference value.Second, Transmission and hydraulic oil brands in (slightly)Third, Fluid Nien transmission of the oil transmission fluid requirements may Nien Tien National Petroleum Corporation December thickness operational changes are divided into two categories : one category is in operation slick thickness constant fluid Nien transmission, such as silicone oil slick thickness using fans is fixed, changes in the operational work of the degree to which oil-exporting rotational speed. Another operation is slick thickness is variable fluid Nien transmission, such fluid Nien Nien transmission products including fluid mechanics using, liquid Nien brakes, fluids Nien dynamometer, fluid Nien shaft coupling, fluid mechanics Nien devices. Current applications are more fluid mechanics using Nien, fluid mechanics devices and silicone oil Nien fans Clutch.1、Fluid mechanics using Nien and transmission oil fluid mechanics using Nien through its owners, driven friction between the film to a number of oil transmission power, relying on the apparent effectiveness initiative friction films "draw" driven friction with the direction of rotation films, transmission moment with oil viscosity, two films - "goes bad" proportional, and with oil thickness (films gap) negatively. Initiative friction films and imported axle and power machine linked to the importation of rotational speed as constants. Driven friction films and the work associated with the export of axle, and the output rotational speed with control pressure changes, spherical tank pressure control, a slick filmthinning, export rotational speed rise, and vice versa. When the control pressure enough, the owners, driven friction films together into the transmission straight. When sufficient pressure control small owners, driven films from friction, zero export rotational speed. Nien in fluid mechanics using rotational speed than 0>1 change from the process of film-friction conditions showing a liquid friction "(a mechanical liquid) mixed friction" (purely mechanical) border friction. Therefore fluid mechanics using Nien are in the process of separation-state governor, the state governor and the state face. Work in fluid liquid is the role of transmission Nien transmission power, heat dissipation and cooling lubricant should have the following functions : (1) the appropriate viscosity. (2) is a good lubricant performance (greasiness and very pressurised nature). (3) a good oxidation insecurities. (4) higher than the thermal capacity and higher heat conductivity. In addition to the above requirements, but also work with rustproof liquid role, anti-bubble capacity, congeal points lower, flash point should be high, not volatile, non-toxic. Nien currently made in China fluid mechanics using more oil as a hydraulic transmission work on the 8th of liquid. The domestic fluid mechanics using a TL - Nien and HC type rated rotational speed mostly 1500r/min, individual 3000r/min. 75kW power transmission smallest, the largest of 1100kW. Fluid mechanics starts with the mechanics of hydraulic Nien coupled devices, are in the rotational speed electrical driven downward in the low-speed, power and small, inefficient. To this end in fluid mechanics using input Nien before or after the installation of vertical transmission-export, or to meet with the power machine and the matching machine work, so a new device -- liquid Nien governor devices.2、Fluid mechanics devices Nien current production and application of two different structures liquid Nien governor devices, a category is the U.S. Philadelphia drove parallel axle fluid production company Nien governor devices into rotational speed 1785r/min exporting rotational speed 5000r/min, transmitting power to 5200kW. My hill Xian too Salihcoal mine in the smaller Daishishusongji specifications. Oil is brought by the United States of its transmission. Baoding propeller factory design, produced with structurally similar products. Another is the United States Dodge (Dodge) companies CST fluid mechanics devices Nien, it is in Park pillar gear -- planetary reducer round of the robustness of the export-round, and export axis (connecting the Sun round), in parallel with export large Chijuan fluid mechanics using Nien (driven friction films fixed), start-up liquid separation Nien governor in the state starts (idling), gradually increasing pressure control, when his transmission torque and the torque equivalent output bearings, export axle (with load) started turning and continue to increase the pressure until the joint control of the situation, the export axle assume full power output. CST fluid mechanics device known as Nien large Daishishusongji soft start system in the country's major coal Daishishusongji already applied. CST series products, the importation of rotational speed 1483r/min, rated slowdown than to 15.38~57.66, transmitting power scope 702~3115kW. CST series of products supplied by the United States dedicated hydraulic transmission oil.3、Silicone oil producing fans with liquid silicone oil work of the fan clutch, driven plate with a 78-98 derby leaves, the two derby leaves mutual alternate inserted, a number Park derby gap (oil), use these links, the sticky oil to impart momentum. The process of routing thickness unchanged through changes Chongyou volume and the size of the area to exploration by sheared governor.Engine in the appropriate temperature can be higher fuel efficiency, overheating is not too cold. Automotive firm to offer fans of silicone oil and engine linked driven sites linked with the fans, for liquid silicone oil viscosity larger. On temperature devices for cooling water to control the rear airflow temperature feelings Chongyou volume. When the engine cooling water temperature low, the air currents temperature low temperature equipment made Chongyou small amount of oil shearedsmall size, transmission moment small, low rotational speed fans for the engine cooling capacity low. Conversely, when the engine cooling water temperature is high, the fans rotational speed is high, awareness of the engine cooling effect. This will allow a regular in the most appropriate temperature. Fuel efficiency, noise small, extended engine life.Silicone oil used silicone oil is a fan using synthetic lubricants, not petroleum refining come from. It is the semi-organic silicon polymers or copolymer, containing duplicate silicon modules for yuan oxygen machine backbone, and the silicon atoms along the chain, replace clustering levonorgestrel, the general chain-guns. To meet the prescribed performance requirements, availability of different organic polymers to replace the base elements or the size of the adjustment (that is, to change its molecular weight), to change its viscosity or acquire other properties.Silicone oil depends on the physical properties of polymer molecular structure, such as molecular weight, organic genetic types and quantity, location and length of extension chain. In the liquid oil thickness constant use silicone oil Nien transmission of the main reasons is that it has a high viscosity, good performance and strong resistance Nien Wen sheared capacity.Silicone oil can be used in all types of vehicles using fans, currently our applications are mainly jeeps, and other vehicles Beijing 130. Motor oil production plant with Beijing and Changchun First Automobile Works Bengchang units.液压传动和传动油流体传动包括气体(压)传动和液体传动，液体传动分为液压传动、液力传动和液粘传动。
液压专业毕业设计外文翻译有译文外文文献值得收藏哦
外文原文：The Analysis of Cavitation Problems in the Axial Piston Pumpshu WangEaton Corporation，14615 Lone Oak Road,Eden Prairie，MN 55344This paper discusses and analyzes the control volume of a piston bore constrained by the valve plate in axial piston pumps。
The vacuum within the piston bore caused by the rise volume needs to be compensated by the flow; otherwise, the low pressure may cause the cavitations and aerations。
In the research, the valve plate geometry can be optimized by some analytical limitations to prevent the piston pressure below the vapor pressure。
The limitations provide the design guide of the timings and overlap areas between valve plate ports and barrel kidneys to consider the cavitations and aerations。
_DOI: 10。
1115/1.4002058_ Keywords: cavitation ，optimization, valve plate，pressure undershoots 1 IntroductionIn hydrostatic machines，cavitations mean that cavities or bubbles form in the hydraulic liquid at the low pressure and collapse at the high pressure region, which causes noise，vibration，and less efficiency.Cavitations are undesirable in the pump since the shock waves formed by collapsed may be strong enough to damage components. The hydraulic fluid will vaporize when its pressure becomes too low or when the temperature is too high. In practice，a number of approaches are mostly used to deal with the problems：（1) raise the liquid level in the tank，(2）pressurize the tank, （3）booster the inlet pressure of the pump，（4) lower the pumping fluid temperature，and （5) design deliberately the pump itself.Many research efforts have been made on cavitation phenomena in hydraulic machine designs。
液压系统-文献翻译
Hydraulic SystemThere are only three basic methods of transmitting power: electrical, mechanical, and fluid power. Most applications actually use a combination of the three methods to obtain the most efficient overall system. To properly determine which principle method to use, it is important to know the salient features of each type. For example, fluid systems can transmit power more economically over greater distances than can mechanical types. However, fluid systems are restricted to shorter distances than are electrical systems.Hydraulic power transmission system are concerned with the generation, modulation, and control of pressure and flow, and in general such systems include:1.Pumps which convert available power from the prime mover to hydraulic power at the actuator.2.Valves which control the direction of pump-flow, the level of power produced, and the amount of fluid-flow to the actuators. The power level is determined by controlling both the flow and pressure level.3.Actuators which convert hydraulic power to usable mechanical power output at the point required.4.The medium, which is a liquid, provides rigid transmission and control as well as lubrication of components, sealing in valves, and cooling of the system.5.Connectors which link the various system components, provide power conductors for the fluid under pressure, and fluid flow return to tank (reservoir).6.Fluid storage and conditioning equipment which ensure sufficient quality and quantity as well as cooling of the fluid.Hydraulic systems are used in industrial applications such as stamping presses, steel mills , and general manufacturing , agricultural machines , mining industry , aviation , space technology , deep-sea exploration ,transportation , marinetechnology , and offshore gas petroleum exploration . In short, very few people get through a day of their lives without somehow benefiting from the technology of hydraulics.The secret of hydraulic system’s success and widespread use is its versatility and manageability. Fluid power is not hindered by the geometry of the machine as is the case in mechanical systems. Also, power can be transmitted in almost limitless quantities because fluid systems are not so limited by the physical limitations of materials as are the electrical systems. For example, the performance of an electromagnet is limited by the saturation limit of steel. On the other hand, the power limit of fluid systems is limited only by the strength capacity of the material.Industry is going to depend more and more on automation in order to increase productivity. This includes remote and direct control of production operations, manufacturing processes, and materials handling. Fluid power is the muscle of automation because of advantages in the following four major categories.Ease and accuracy of control. By the use of simple levers and push buttons, the operator of a fluid power systems can readily start, stop, speed up or slow down, and position force which provide any desired horsepower with tolerances as precise as one ten-thousandth of an inch.Multiplication of force. A fluid power system (without using cumbersome gears, pulleys, and levers) can multiply forces simply and efficiently from a fraction of an ounce to several hundred tons of output.Constant force or torque. Only fluid power systems are capable of providing constant force or torque regardless of speed changes. This is accomplished whether the work output moves a few inches per hour, several hundred inches per minute, a few revolutions per hour, or thousands of revolutions per minute.Simplicity, safety, economy. In general, fluid power systems use fewer movingparts than comparable mechanical or electrical systems. Thus, they are simpler to maintain and operate. This, in turn, maximizes safety, compactness, and reliability. For example, a new power steering control designed has made all other kinds of power systems obsolete on many off-highway vehicles. The steering unit consists of a manually operated directional control valve and meter in a single body. Because the sterring unit is fully fluid-linked, mechanical linkages, universal joints, bearings, reduction gears, ect . are eliminated. This provides a simple,compact systems.In addition, very little input torque is required to produce the control needed for the toughest applications. This is important where limitations of control space require a small sterring wheel and it becomes necessary to reduce operator fatigue.Additional benefits of fluid power systems include instantly reversible motion, automatic protection against overloads, and infinitely variable speed control. Fluid power systems also have the highest horsepower per weight ratio of any known power source. In spite of all these highly desirable features of fluid power, it is not a panacea for all power transmission problems. Hydraulic systems also have some drawbacks. Hydraulic oils are messy, and leakage is impossible to completely. Also, most hydraulic oils can cause fires if an oil leak occurs in area of hot equipment. There are only three basic methods of transmitting power: electrical, mechanical, and fluid power. Most applications actually use a combination of the three methods to obtain the most efficient overall system. To properly determine which principle method to use, it is important to know the salient features of each type. For example, fluid systems can transmit power more economically over greater distances than can mechanical types. However, fluid systems are restricted to shorter distances than are electrical systems.Hydraulic power transmission system are concerned with the generation, modulation, and control of pressure and flow, and in general such systems include:Pumps which convert available power from the prime mover to hydraulic power at the actuator.Valves which control the direction of pump-flow, the level of power produced, and the amount of fluid-flow to the actuators. The power level is determined by controlling both the flow and pressure level.Actuators which convert hydraulic power to usable mechanical power output at the point required.The medium, which is a liquid, provides rigid transmission and control as well as lubrication of components, sealing in valves, and cooling of the system.Connectors which link the various system components, provide power conductors for the fluid under pressure, and fluid flow return to tank (reservoir).Fluid storage and conditioning equipment which ensure sufficient quality and quantity as well as cooling of the fluid.Hydraulic systems are used in industrial applications such as stamping presses, steel mills , and general manufacturing , agricultural machines , mining industry , aviation , space technology , deep-sea exploration ,transportation , marine technology , and offshore gas petroleum exploration . In short, very few people get through a day of their lives without somehow benefiting from the technology of hydraulics.The secret of hydraulic system’s success and widespread use is its versatility and manageability. Fluid power is not hindered by the geometry of the machine as is the case in mechanical systems. Also, power can be transmitted in almost limitless quantities because fluid systems are not so limited by the physical limitations of materials as are the electrical systems. For example, the performance of an electromagnet is limited by the saturation limit of steel. On the other hand, the power limit of fluid systems is limited only by the strength capacity of the material.Industry is going to depend more and more on automation in order to increase productivity. This includes remote and direct control of production operations, manufacturing processes, and materials handling. Fluid power is the muscle of automation because of advantages in the following four major categories.1. Ease and accuracy of control. By the use of simple levers and push buttons, the operator of a fluid power systems can readily start, stop, speed up or slow down, and position force which provide any desired horsepower with tolerances as precise as one ten-thousandth of an inch.2. Multiplication of force. A fluid power system (without using cumbersome gears, pulleys, and levers) can multiply forces simply and efficiently from a fraction of an ounce to several hundred tons of output.3. Constant force or torque. Only fluid power systems are capable of providing constant force or torque regardless of speed changes. This is accomplished whether the work output moves a few inches per hour, several hundred inches per minute, a few revolutions per hour, or thousands of revolutions per minute.4. Simplicity, safety, economy. In general, fluid power systems use fewer moving parts than comparable mechanical or electrical systems. Thus, they are simpler to maintain and operate. This, in turn, maximizes safety, compactness, and reliability. For example, a new power steering control designed has made all other kinds of power systems obsolete on many off-highway vehicles. The steering unit consists of a manually operated directional control valve and meter in a single body. Because the sterring unit is fully fluid-linked, mechanical linkages, universal joints, bearings, reduction gears, ect . are eliminated. This provides a simple,compact systems.In addition, very little input torque is required to produce the control needed for the toughest applications. This is important where limitations of controlspace require a small sterring wheel and it becomes necessary to reduce operator fatigue.Additional benefits of fluid power systems include instantly reversible motion, automatic protection against overloads, and infinitely variable speed control. Fluid power systems also have the highest horsepower per weight ratio of any known power source. In spite of all these highly desirable features of fluid power, it is not a panacea for all power transmission problems. Hydraulic systems also have some drawbacks. Hydraulic oils are messy, and leakage is impossible to completely. Also, most hydraulic oils can cause fires if an oil leak occurs in area of hot equipment.液压系统仅有以下三种基本方法传递动力：电气，机械和流体。
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西京学院本科毕业设计外文资料翻译系别：专业：姓名：学号：2014 年 3 月 13 日译文液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质，以水压机的形式将其应用于工业上，诞生了世界上第一台水压机。
1905年将工作介质水改为油，又进一步得到改善。
第一次世界大战(1914-1918)后液压传动广泛应用，特别是1920年以后，发展更为迅速。
液压元件大约在 19 世纪末 20 世纪初的20年间，才开始进入正规的工业生产阶段。
1925 年维克斯(F.Vikers)发明了压力平衡式叶片泵,为近代液压元件工业或液压传动的逐步建立奠定了基础。
20 世纪初康斯坦丁•尼斯克(G•Constantimsco)对能量波动传递所进行的理论及实际研究;1910年对液力传动(液力联轴节、液力变矩器等)方面的贡献，使这两方面领域得到了发展。
第二次世界大战(1941-1945)期间,在美国机床中有30%应用了液压传动。
应该指出,日本液压传动的发展较欧美等国家晚了近 20 多年。
在 1955 年前后 , 日本迅速发展液压传动,1956 年成立了“液压工业会”。
近20~30 年间，日本液压传动发展之快，居世界领先地位。
液压传动有许多突出的优点，因此它的应用非常广泛，如一般工业用的塑料加工机械、压力机械、机床等；行走机械中的工程机械、建筑机械、农业机械、汽车等；钢铁工业用的冶金机械、提升装置、轧辊调整装置等；土木水利工程用的防洪闸门及堤坝装置、河床升降装置、桥梁操纵机构等；发电厂涡轮机调速装置、核发电厂等等；船舶用的甲板起重机械（绞车）、船头门、舱壁阀、船尾推进器等；特殊技术用的巨型天线控制装置、测量浮标、升降旋转舞台等；军事工业用的火炮操纵装置、船舶减摇装置、飞行器仿真、飞机起落架的收放装置和方向舵控制装置等。
一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助元件和液压油。
动力元件的作用是将原动机的机械能转换成液体的压力能，指液压系统中的油泵，它向整个液压系统提供动力。
液压泵的结构形式一般有齿轮泵、叶片泵和柱塞泵。
执行元件(如液压缸和液压马达)的作用是将液体的压力能转换为机械能，驱动负载作直线往复运动或回转运动。
控制元件(即各种液压阀)在液压系统中控制和调节液体的压力、流量和方向。
根据控制功能的不同，液压阀可分为压力控制阀、流量控制阀和方向控制阀。
压力控制阀又分为益流阀(安全阀)、减压阀、顺序阀、压力继电器等；流量控制阀包括节流阀、调整阀、分流集流阀等；方向控制阀包括单向阀、液控单向阀、梭阀、换向阀等。
根据控制方式不同，液压阀可分为开关式控制阀、定值控制阀和比例控制阀。
辅助元件包括油箱、滤油器、油管及管接头、密封圈、压力表、油位油温计等。
液压油是液压系统中传递能量的工作介质，有各种矿物油、乳化液和合成型液压油等几大类。
液压系统的作用就是帮助人类做工。
主要是由执行元件把压力变成转动或往复运动。
液压系统由信号控制和液压动力两部分组成，信号控制部分用于驱动液压动力部分中的控制阀动作。
液压动力部分采用回路图方式表示，以表明不同功能元件之间的相互关系。
液压源含有液压泵、电动机和液压辅助元件；液压控制部分含有各种控制阀，其用于控制工作油液的流量、压力和方向；执行部分含有液压缸或液压马达，其可按实际要求来选择。
在分析和设计实际任务时，一般采用方框图显示设备中实际运行状况。
空心箭头表示信号流，而实心箭头则表示能量流。
基本液压回路中的动作顺序—控制元件（二位四通换向阀）的换向和弹簧复位、执行元件（双作用液压缸）的伸出和回缩以及溢流阀的开启和关闭。
对于执行元件和控制元件，演示文稿都是基于相应回路图符号，这也为介绍回路图符号作了准备。
根据系统工作原理，您可对所有回路依次进行编号。
如果第一个执行元件编号为0，则与其相关的控制元件标识符则为1。
如果与执行元件伸出相对应的元件标识符为偶数，则与执行元件回缩相对应的元件标识符则为奇数。
不仅应对液压回路进行编号，也应对实际设备进行编号，以便发现系统故障。
DIN ISO1219-2标准定义了元件的编号组成，其包括下面四个部分：设备编号、回路编号、元件标识符和元件编号。
如果整个系统仅有一种设备，则可省略设备编号。
实际中，另一种编号方式就是对液压系统中所有元件进行连续编号，此时，元件编号应该与元件列表中编号相一致。
这种方法特别适用于复杂液压控制系统，每个控制回路都与其系统编号相对应与机械传动、电气传动相比，液压传动具有以下优点：1、液压传动的各种元件，可以根据需要方便、灵活地来布置。
2、重量轻、体积小、运动惯性小、反应速度快。
3、操纵控制方便，可实现大范围的无级调速（调速范围达2000：1）。
4、可自动实现过载保护。
5、一般采用矿物油作为工作介质，相对运动面可自行润滑，使用寿命长；6、很容易实现直线运动/7、很容易实现机器的自动化，当采用电液联合控制后，不仅可实现更高程度的自动控制过程，而且可以实现遥控。
液压系统的缺点：1、由于流体流动的阻力和泄露较大，所以效率较低。
如果处理不当，泄露不仅污染场地，而且还可能引起火灾和爆炸事故。
2、由于工作性能易受到温度变化的影响，因此不宜在很高或很低的温度条件下工作。
3、液压元件的制造精度要求较高，因而价格较贵。
4、由于液体介质的泄露及可压缩性影响，不能得到严格的传动比。
5、液压传动出故障时不易找出原因；使用和维修要求有较高的技术水平。
在液压系统及其系统中，密封装置用来防止工作介质的泄漏及外界灰尘和异物的侵入。
其中起密封作用的元件，即密封件。
外漏会造成工作介质的浪费，污染机器和环境，甚至引起机械操作失灵及设备人身事故。
内漏会引起液压系统容积效率急剧下降，达不到所需要的工作压力，甚至不能进行工作。
侵入系统中的微小灰尘颗粒，会引起或加剧液压元件摩擦副的磨损，进一步导致泄漏。
因此，密封件和密封装置是液压设备的一个重要组成部分。
它的工作的可靠性和使用寿命，是衡量液压系统好坏的一个重要指标。
除间隙密封外，都是利用密封件，使相邻两个偶合表面间的间隙控制在需要密封的液体能通过的最小间隙以下。
在接触式密封中，分为自封式压紧型密封和自封式自紧型密封（即唇形密封）两种。
液压系统的三大顽疾1、发热由于传力介质（液压油）在流动过程中存在各部位流速的不同，导致液体内部存在一定的内摩擦，同时液体和管路内壁之间也存在摩擦，这些都是导致液压油温度升高的原因。
温度升高将导致内外泄漏增大，降低其机械效率。
同时由于较高的温度，液压油会发生膨胀，导致压缩性增大，使控制动作无法很好的传递。
解决办法：发热是液压系统的固有特征，无法根除只能尽量减轻。
使用质量好的液压油、液压管路的布置中应尽量避免弯头的出现、使用高质量的管路以及管接头、液压阀等。
2、振动液压系统的振动也是其痼疾之一。
由于液压油在管路中的高速流动而产生的冲击以及控制阀打开关闭过程中产生的冲击都是系统发生振动的原因。
强的振动会导致系统控制动作发生错误，也会使系统中一些较为精密的仪器发生错误，导致系统故障。
解决办法：液压管路应尽量固定，避免出现急弯。
避免频繁改变液流方向，无法避免时应做好减振措施。
整个液压系统应有良好的减振措施，同时还要避免外来振源对系统的影响。
3、泄漏液压系统的泄漏分为内泄漏和外泄漏。
内泄漏指泄漏过程发生在系统内部，例如液压缸活塞两边的泄漏、控制阀阀芯与阀体之间的泄漏等。
内泄漏虽然不会产生液压油的损失，但是由于发生泄漏，既定的控制动作可能会受到影响，直至引起系统故障。
外泄漏是指发生在系统和外部环境之间的泄漏。
液压油直接泄漏到环境中，除了会影响系统的工作环境外，还会导致系统压力不够引发故障。
泄漏到环境中的液压油还有发生火灾的危险。
解决办法：采用质量较好的密封件，提高设备的加工精度。
另：对于液压系统这三大顽疾，有人进行了总结：“发烧、拉稀带得瑟”（这位总结者是东北人）。
液压系统用于升降机，挖掘机，泵站，强夯机，起重机，等等大型工业，建筑，工厂，企业，还有升降机，升降平台，登车桥等等行业。
液压元件将向高性能、高质量、高可靠性、系统成套方向发展；向低能耗、低噪声、振动、无泄漏以及污染控制、应用水基介质等适应环保要求方向发展；开发高集成化高功率密度、智能化、机电一体化以及轻小型微型液压元件；积极采用新工艺、新材料和电子、传感等高新技术。
---- 液力偶合器向高速大功率和集成化的液力传动装置发展，开发水介质调速型液力偶合器和向汽车应用领域发展，开发液力减速器，提高产品可靠性和平均无故障工作时间；液力变矩器要开发大功率的产品，提高零部件的制造工艺技术，提高可靠性，推广计算机辅助技术，开发液力变矩器与动力换档变速箱配套使用技术；液粘调速离合器应提高产品质量，形成批量，向大功率和高转速方向发展。
气动行业：----产品向体积小、重量轻、功耗低、组合集成化方向发展，执行元件向种类多、结构紧凑、定位精度高方向发展；气动元件与电子技术相结合，向智能化方向发展；元件性能向高速、高频、高响应、高寿命、耐高温、耐高压方向发展，普遍采用无油润滑，应用新工艺、新技术、新材料。
（1）采用的液压元件高压化，连续工作压力达到40Mpa，瞬间最高压力达到48Mpa；（2）调节和控制方式多样化；（3）进一步改善调节性能，提高动力传动系统的效率；（4）发展与机械、液力、电力传动组合的复合式调节传动装置；（5）发展具有节能、储能功能的高效系统；（6）进一步降低噪声；（7）应用液压螺纹插装阀技术，紧凑结构、减少漏油。
原文Hydraulic presser drive and air pressure drive hydraulic fluid as the transmission is made according to the 17th century, Pascal's principle of hydrostatic pressure to drive the development of an emerging technology, the United Kingdom in 1795 • Braman Joseph (Joseph Braman ,1749-1814), in London water as a medium to form hydraulic press used in industry, the birth of the world's first hydraulic press. Media work in 1905 will be replaced by oil-water and further improved.After the World War I (1914-1918) ,because of the extensive application of hydraulic transmission, espec- ially after 1920, more rapid development. Hydraulic components in the late 19th century about the early 20th century, 20 years, only started to enter the formal phase of industrial production. 1925 Vickers (F. Vikers) the invention of the pressure balanced vane pump, hydraulic components for the modern industrial or hydraulic transmission of the gradual establish ment of the foundation. The early 20th century G • Constantimscofluct- uations of the energy carried out by passing theoretical and practical research; in 1910 on the hydraulic trans- mission (hydraulic coupling, hydraulic torque converter, etc.) contributions, so that these two areas of develo- pment.The Second World War (1941-1945) period, in the United States 30% of machine tool applications in the hydraulic transmission. It should be noted that the development of hydraulic transmission in Japan than Europe and the United States and other countries for nearly 20 years later. Before and after in 1955, the rapid development of Japan's hydraulic drive, set up in 1956, "Hydraulic Industry." Nearly 20 to 30 years, the development of Japan's fast hydraulic transmission, a world leader.Hydraulic transmission There are many outstanding advantages, it is widely used, such as general industr- ial use of plastics processing machinery, the pressure of machinery, machine tools, etc.; operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.; iron and steel indu- stry metallurgical machinery, lifting equipment, such as roller adjustment device; civil water projects with flo- od control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions; speed turbine power plant installations, nuclear power plants, etc.; ship from the deck heavy machinery (winch), the bow doors, bulkhead valve, stern thruster, etc.; special antenna technology giant with control devices, measu- rement buoys, movements such as rotating stage; military-industrial control devices used in artillery, ship anti- rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devi- ces.A complete hydraulic system consists of five parts, namely, power components, the implementation of co- mponents, control components, auxiliary components and hydraulic oil.The role of dynamic components of the original motive fluid into mechanical energy to the pressure that the hydraulic system of pumps, it is to power the entire hydraulic system. The structure of the form of hydra- ulic pump gears are generally pump, vane pump and piston pump.Implementation of components (such as hydraulic cylinders and hydraulic motors) which is the pressure of the liquid can be converted to mechanical energy to drive the load for a straight line reciprocating movement or rotational movement.Control components (that is, the various hydraulic valves) in the hydraulic system to control and regulate the pressure of liquid, flow rate and direction. According to the different control functions, hydraulic pressure control valve can be divided into valves, flow control valves and directional control valve. Pressure control valves are divided into benefits flow valve (safety valve), pressure relief valve, sequence valve, pressure relays, etc.; flow control valves including throttle, adjusting the valves, flow diversion valve sets, etc.; directional control valve includes a one-way valve , one-way fluid control valve, shuttle valve, valve and so on. Under the control of different ways, can be divided into the hydraulic valve control switch valve, control valve and set the value of the ratio control valve.Auxiliary components, including fuel tanks, oil filters, tubing and pipe joints, seals, pressure gauge, oil level, such as oil dollars.Hydraulic oil in the hydraulic system is the work of the energy transfer medium, there are a variety of mineral oil, emulsion oil hydraulic molding Hop categories.The role of the hydraulic system is to help humanity work. Mainly by the implementation of components to rotate or pressure into a reciprocating motion.Hydraulic system and hydraulic power control signal is composed of two parts, the signal control of some parts of the hydraulic power used to drive the control valve movement.Part of the hydraulic power means that the circuit diagram used to show the different functions of the interrelationship between components. Containing the source of hydraulic pump, hydraulic motor and auxiliary components; hydraulic control part contains a variety of control valves, used to control the flow of oil, pressure and direction; operative or hydraulic cylinder with hydraulic motors, according to the actual requirements of their choice.In the analysis and design of the actual task, the general block diagram shows the actual operation of equi - pment. Hollow arrow indicates the signal flow, while the solid arrows that energy flow.Basic hydraulic circuit of the action sequence - Control components (two four-way valve) and the spring to reset for the implementation of components (double-acting hydraulic cylinder), as well as theextending and retracting the relief valve opened and closed . For the implementation of components and control components, presentations are based on the corresponding circuit diagram symbols, it also introduced ready made circuit diagram symbols.Working principle of the system, you can turn on all circuits to code. If the first implementation of components numbered 0, the control components associated with the identifier is 1. Out with the implementation of components corresponding to the identifier for the even components, then retracting and implementation of components corresponding to the identifier for the odd components. Hydraulic circuit carried out not only to deal with numbers, but also to deal with the actual device ID, in order to detect system failures.DIN ISO1219-2 standard definition of the number of component composition, which includes the following four parts: device ID, circuit ID, component ID and component ID. The entire system if only one device, device number may be omitted.Practice, another way is to code all of the hydraulic system components for numbers at this time, components and component code should be consistent with the list of numbers. This method is particularly applicable to complex hydraulic control system, each control loop are the corresponding number with the systemWith mechanical transmission, electrical transmission compared to the hydraulic drive has the following advantages:1, a variety of hydraulic components, can easily and flexibly to layout.2, light weight, small size, small inertia, fast response.3, to facilitate manipulation of control, enabling a wide range of stepless speed regulation (speed range of 2000:1).4, to achieve overload protection automatically.5, the general use of mineral oil as a working medium, the relative motion can be self-lubricating surface, long service life;6, it is easy to achieve linear motion /7, it is easy to achieve the automation of machines, when the joint control of the use of electro-hydraulic, not only can achieve a higher degree of process automation, and remote control can be achieved.The shortcomings of the hydraulic system:1, as a result of the resistance to fluid flow and leakage of the larger, so less efficient. If not handledproperly, leakage is not only contaminated sites, but also may cause fire and explosion.2, vulnerable performance as a result of the impact of temperature change, it would be inappropriate in the high or low temperature conditions.3, the manufacture of precision hydraulic components require a higher, more expensive and hence the price.4, due to the leakage of liquid medium and the compressibility and can not be strictly the transmission ratio.5, hydraulic transmission is not easy to find out the reasons for failure; the use and maintenance requirements for a higher level of technology.In the hydraulic system and its system, the sealing device to prevent leakage of the work of media within and outside the dust and the intrusion of foreign bodies. Seals played the role of components, namely seals. Medium will result in leakage of waste, pollution and environmental machinery and even give rise to malfunctioning machinery and equipment for personal accident. Leakage within the hydraulic system will cause a sharp drop in volumetric efficiency, amounting to less than the required pressure, can not even work. Micro-invasive system of dust particles, can cause or exacerbate friction hydraulic component wear, and further lead to leakage.Therefore, seals and sealing device is an important hydraulic equipment components. The reliability of its work and life, is a measure of the hydraulic system an important indicator of good or bad. In addition to the closed space, are the use of seals, so that two adjacent coupling surface of the gap between the need to control the liquid can be sealed following the smallest gap. In the contact seal, pressed into self-seal-style and self-styled self-tight seal (ie, sealed lips) two.The three hydraulic system diseases1, as a result of heat transmission medium (hydraulic oil) in the flow velocity in various parts of the existence of different, resulting in the existence of a liquid within the internal friction of liquids and pipelines at the sam- e time there is friction between the inner wall, which are a result of hydraulic the reasons for the oil tempera- ture. Temperature will lead to increased internal and external leakage, reducing its mechanical efficiency. At the same time as a result of high temperature, hydraulic oil expansion will occur, resulting in increased com- pression, so that action can not be very good control of transmission. Solution: heat is the inherent characte -ristics of the hydraulic system, not only to minimize eradication. Use a good quality hydraulic oil, hydraulic piping arrangement should be avoided as far as possible the emergence of bend, the use of high-quality pipe and fittings, hydraulic valves, etc.2, the vibration of the vibration of the hydraulic system is also one of its malaise. As a result of hydraulic oil in the pipeline flow of high-speed impact and the control valve to open the closure of the impact of the process are the reasons for the vibration system. Strong vibration control action will cause the system to error, the system will also be some of the more sophisticated equipment error, resulting in system failures. Solutions: hydraulic pipe should be fixed to avoid sharp bends. To avoid frequent changes in flow direction, can not avoid damping measures should be doing a good job. The entire hydraulic system should have a good damping measures, while avoiding the external local oscillator on the system.3, the leakage of the hydraulic system leak into inside and outside the leakage leakage. Leakage refers to the process with the leak occurred in the system, such as hydraulic piston-cylinder on both sides of the leakage, the control valve spool and valve body, such as between the leakage. Although no internal leakage of hydra- ulic fluid loss, but due to leakage, the control of the established movements may be affected until the cause system failures. Outside means the occurrence of leakage in the system and the leakage between the external environment. Direct leakage of hydraulic oil into the environment, in addition to the system will affect the working environment, not enough pressure will cause the system to trigger a fault. Leakage into the enviro- nment of the hydraulic oil was also the danger of fire. Solution: the use of better quality seals to improve the machining accuracy of equipment.Another: the hydraulic system for the three diseases, it was summed up: "fever, with a father拉稀" (This is the summary of the northeast people). Hydraulic system for the lifts, excavators, pumping station, dynamic, crane, and so on large-scale industry, construction, factories, enterprises, as well as elevators, lifting platforms, Deng Axle industry and so on.Hydraulic components will be high-performance, high-quality, high reliability, the system sets the direction of development; to the low power, low noise, vibration, without leakage, as well as pollution control, water-based media applications to adapt to environmental requirements, such as the direction of development; the development of highly integrated high power density, intelligence, mechatronics and micro-light mini-hydraulic components; active use of new techniques, new materials and electronics, sensing and other high-tech.---- Hydraulic coupling to high-speed high-power and integrated development of hydraulic transmission equ- ipment, development of water hydraulic coupling medium speed and the field of automotive applications to develop hydraulic reducer, improve product reliability and working hours MTBF; hydraulic torque converter to the development of high-power products, parts and components to improve the manufacturing process tech -nology to improve reliability, promote computer-aided technology, thedevelopment of hydraulic torque con- verter and power shift transmission technology supporting the use of ; Clutch fluid viscosity should increase the quality of products, the formation of bulk to the high-power and high-speed direction.Pneumatic Industry:---- Products to small size, light weight, low power consumption, integrated portfolio of development, the implementation of the various types of components, compact structure, high positioning accuracy of the direction of development; pneumatic components and electronic technology, to the intelligent direction of development; component performance to high-speed, high-frequency, high-response, high-life, high temp- erature, high voltage direction, commonly used oil-free lubrication, application of new technology, new technology and new materials.(1) used high-pressure hydraulic components and the pressure of continuous work to reach 40Mpa, the maximum pressure to achieve instant 48Mpa;(2) diversification of regulation and control;(3) to further improve the regulation performance, increase the efficiency of the powertrain;(4) development and mechanical, hydraulic, power transmission of the composite portfolio adjustment gear;(5) development of energy saving, energy efficient system function;(6) to further reduce the noise;(7) Application of Hydraulic Cartridge Valves thread technology, compact structure, to reduce the oil spill.。