Crash sensor

from Wikipedia, the free encyclopedia

A crash sensor , or impact sensor , is used in motor vehicles to detect an impact of the vehicle against an obstacle.

Once the sensor has detected an impact, it sends an electrical pulse to various control units, which in turn activate various occupant protection systems . Depending on the equipment of the vehicle, this includes airbags , belt force limiters , belt tensioners and roll bars . In some vehicle types, the unlocking of the vehicle doors is also initiated. The triggering of the crash sensor is recorded in the accident data memory.

Older crash sensors only recognize an impact and activate the occupant protection systems as soon as a specified threshold value for vehicle deceleration is exceeded. Modern, so-called intelligent , sensors, on the other hand, can also detect the severity of the impact and, depending on this, activate different occupant protection systems, which can reduce the risk of airbag-induced injuries to vehicle occupants.

Sensors

Depending on the measurement method used, crash sensors can be divided into 3 groups.

Acceleration sensors

Acceleration sensors react to an abrupt stop of the vehicle; the signal is typically triggered at acceleration values ​​of 3 to 5 g.

Pressure sensors

This type of sensor is mostly used to detect a side impact . The sensors detect a pressure increase in the cavity of the vehicle doors. They react a little faster than accelerometers.

Crash Impact Sound Sensing (CISS)

This latest generation of sensors detect an accident based on changes in the structure-borne sound of the body panel that deforms upon impact. Their response time is even shorter than that of pressure sensors.