Design Of Multi-threshold Crash Sensor For Vehicle Safety System

Different from accelerometer, a multi-threshold crash sensor can be switched between different states quickly according to the external acceleration without complex auxiliary circuits and control unit. With many advantages like a combination of inertia sensing with threshold actuation, zero power consumption and high reliability, multi-threshold crash sensors have a wide range of application in vehicle active safety systems, weapons systems development and fall protection system.Currently, crash sensor has many defects, which are, single directional and threshold value, contact force instability, and weak anti-overload ability. Not only it is difficult to meet the sensitivity requirement of the impact strength at the multi-level vehicle security system setup but also conducting a comprehensive analysis of key factors of the sensing accuracy of the impact crash sensors and stability of the contact. The aim of this paper is to design a new multi-threshold impact sensor, including:1) Considering the detonation conditions and requirements of vehicle airbag, a design method of multi-threshold crash sensor based on non-linear multistable mechanism is proposed. A magnetic contact beam structure is introduced to effectively solve the problem of unstable contact induced by overload.2) Considering the impact of damping of the gas film. Static and dynamic models for the multi-threshold crash sensor are established, and the effect of acceleration threshold and pulse width on switch operation is analyzed. Numerical simulation and experimental results show that the sensor has 6 acceleration thresholds in two directions under the load of 10ms rectangular pulse acceleration. The maximum overload capability of the sensor is up to 15.3 times of the first threshold value of the acceleration, and 4.5 times of the second threshold, and the 2.9 times of the third threshold.3) A research has been done on the impact sensitivity of the multi-threshold crash sensor under the lateral acceleration disturbance and vibration environment. The simulation results show that the multi-threshold crash sensor meet the design requirements under the lateral acceleration of 1 g. And the sensor is able to work in the resonance environment under the amplitude of 10m/s2. The discovery is found to be the numerical simulation and experimental results are substantially agreeable, which verifies the effectiveness and feasibility of the design method of the multi-threshold impact sensor.