汽车安全气囊新技术

HOW SYSTEMS WIKIPEDIA)
GO(FROM

对于早期的汽车，一般设有多个触发碰撞传感器，安装 位置一般在车身的前部和中部，例如车身两侧的翼子板 内侧、前照灯支架下面以及发动机散热器支架两侧等部 位。随着碰撞传感器制造技术的发展，有些汽车将触发 碰撞传感器安装在气囊系统ECU内。防护碰撞传感器一 般都与气囊系统ECU组装在一起，多数安装在驾驶舱内 中央控制台下面。ECU是气囊系统的核心部件，大多安 装在驾驶舱内中央控制台下面。
汽车安全气囊新技术
第六组课题 作用原 理
气体反应
环保新 气体
侧边气 囊
充气二 分法
你想到什么？
安全气囊是“辅助约束系统” （Supplement Restrain System， 缩写为SRS）的一部分，主要是为了 防止汽车碰撞时车内乘员和车内部件 间发生碰撞而造成的伤害，它通常是 作为安全带的辅助安全装置出现，二 者共同作用。
气体发生器
气体发生器内存储有氮化钠或硝酸铵等物质。当汽
车在高速行驶中受到猛烈撞击时，这些物质会迅速 发生分解反应，产生大量气体（无毒无味的氮气占 70%以上），充满气囊。
气体爆炸
Older
airbag systems contained a mixture of sodium azide (NaN3), KNO3, and SiO2. A typical driver-side airbag contains approximately 50-80 g of NaN3, with the larger passenger-side airbag containing about 250 g. Within about 40 milliseconds of impact, all these components react in three separate reactions that produce nitrogen gas. The reactions, in order, are as follows. 2 NaN3 → 2 Na + 3 N2 (g) 10 Na + 2 KNO3 → K2O + 5 Na2O + N2 (g) K2O + Na2O + 2 SiO2 → K2O3Si + Na2O3Si (silicate glass)

The design is conceptually simple; a central Airbag control unit (ACU) (a specific type of ECU) monitors a number of related sensors within the vehicle, including accelerometers, impact sensors, side (door) pressure sensors , wheel speed sensors, gyroscopes, brake pressure sensors, and seat occupancy sensors. The bag itself and its inflation mechanism is concealed within the steering wheel boss (for the driver), or the dashboard (for the front passenger), behind plastic flaps or doors which are designed to "tear open" under the force of the bag inflating. Once the requisite 'threshold' has been reached or exceeded, the airbag control unit will trigger the ignition of a gas generator propellant to rapidly inflate a fabric bag. As the vehicle occupant collides with and squeezes the bag, the gas escapes in a controlled manner through small vent holes. The airbag's volume and the size of the vents in the bag are tailored to each vehicle type, to spread out the deceleration of (and thus force experienced by) the occupant over time and over the occupant's body, compared to a seat belt alone
ＲＥＡＣＴＩＯＮ
ＡＣＣＯＲＤＩＮＧ ＴＯ ＷＩＫＩＰＥＤＩＡ
There
has been a recent effort to find alternative compounds that can be used in airbags which have less toxic byproducts. In a journal article by Akiyoshi et. Al., it was found that for the reaction of the Sr complex nitrate, (Sr(NH2NHCONHNH2)∙(NO3)2 of carbohydrazide (SrCDH) with various oxidizing agents resulted in the evolution of N2 and CO2 gases. Using KBrO3 as the oxidizing agent resulted in the most vigorous reaction as well as the lowest initial temperature of reaction. The N2 and CO2 gases evolved made up 99% of all gases evolved. Nearly all the starting materials won’t decompose until reaching temperatures of 500 °C or higher so this could be a viable option as an air bag gas generator.
汽车行驶过程中，传感器系统不断向控制装置发送速度 变化（或加速度）信息，由气囊控制模块（ECU）对这 些信息加以分析判断，如果所测的加速度、速度变化量 或其它指标超过预定值（即真正发生了碰撞），则囊控 制模块向气体发体发生器发出点火命令。

控制模块（EC大量的气体充满气 囊，产生的气体必须对人体无害，且不 能温度太高，同时要求气体发生器有很 高的可靠性和稳定性。目前气体发生器 主要有压缩气体式、烟火式和混合式三 种型式。混合式气体发生器是压缩气体 式和烟火式相结合的发生器，也是目前 广泛应用一种气体发生器。
ＲＥＡＣＴＩＯＮ
ＡＣＣＯＲＤＩＮＧ ＴＯ ＷＩＫＩＰＥＤＩＡ
According
to a patent, the particle size of the sodium azide, potassium nitrate, and silicon dioxide are important. The NaN3 and KNO3 must be between 10 and 20 µm, while the SiO2 must be between 5 and 10 µm.
ＲＥＡＣＴＩＯＮ ＬＥＳＳ ＴＯＸＩＣ
ＡＣＣＯＲＤＩＮＧ ＴＯ ＷＩＫＩＰＥＤＩＡ
In
a patent containing another plausible alternative to NaN3 driven airbags, the gas generating materials involved the use of guanidine nitrate, 5-amino tetrazole, bitetrazole 5-氨基四氮唑 dehydrate, nitroimidazole, and basic copper nitrate. It was found that these non-azide reagents allowed for a less toxic, lower combustion temperature reaction and more easily disposable air bag inflation system.[citation needed]
(1) (2) (3)
ＲＥＡＣＴＩＯＮ
ＡＣＣＯＲＤＩＮＧ ＴＯ ＷＩＫＩＰＥＤＩＡ

The first reaction is the decomposition of NaN3 under high temperature conditions using an electric impulse. This impulse generates to 300 °C temperatures required for the decomposition of the NaN3 which produces Na metal and N2 gas. Since Na metal is highly reactive, the KNO3 and SiO2 react and remove it, in turn producing more N2 gas. The second reaction shows just that. The reason that KNO3 is used rather than something like NaNO3 is because it is less hygroscopic. It is very important that the materials used in this reaction are not hygroscopic because absorbed moisture can de-sensitize the system and cause the reaction to fail. The final reaction is used to eliminate the K2O and Na2O produced in the previous reactions because the first-period metal oxides are highly reactive. These products react with SiO2 to produce a silicate glass which is a harmless and stable compound.