Rotational speed and lateral acceleration sensor, function - GF42.45-P-4801-04B

Models 163, 203, 209 

General information 

The sensors for capturing rotational speed and lateral acceleration  are combined into the turn rate and lateral acceleration sensor (B24/15)  . This reduces installation space considerably.

The micromechanical sensory system converts the different degrees of acceleration about a vehicle's transversal and vertical axis into electrically usable signals.

The different types of masses are deflected differently according to the movement of the vehicle (cornering or decelerating).

The electronic analysis system captures these signal changes and sends them via the CAN to the control module for the traction systems (N47).

Function of rotational speed sensor 

A micromechanical silicon ring structure (a) which has 8 bridges (b) to allow it to oscillate is used as the sensor element. The oscillations are induced electromagnetically. Rotation acting upon the oscillation structure generates additional forces (Coriolis) which are proportional to the active rotation.

These additional forces are also read out electromagnetically. After conditioning in a sensor-specific ASIC, they are supplied as analog signals to the signal processor inside the instrument cluster.

The measuring principle of the lateral acceleration sensor  is based on a spring/ mass system with a capacitive detector. The voltage is supplied via the ESP control module (N47-5).

Operation 

The lateral acceleration which occurs during cornering causes the spring/mass element to move from its normal position to a position corresponding to the magnitude of the lateral acceleration. Every change in position changes the electrical capacitance of the detector. An electronic analysis system then generates a voltage signal which depends on the capacitance and, therefore, the lateral acceleration of the vehicle. This voltage signal is evaluated by the ESP control module (N47-5).