Electronic Suspension Control Description and Operation
The ZF Sachs electronic suspension control system, individually controls the damping force of each of the 4 shock absorbers in order to keep the vehicle's body as calm as possible. Changes of the damping forces can be accomplished within milliseconds. Suspension characteristics can be changed at any time by activating the sport mode or tour mode.
The electronic suspension control system consists of the following major components
- The suspension control module
- Three body vertical acceleration sensors
- Two front wheel vertical acceleration sensors
- Four shock absorber actuators, which are integrated within the shock absorbers
The suspension control module controls the damping forces according to the following factors
- Vehicle speed
- Steering wheel position
- Engine torque
- Brake pressure
- Body and front wheels vertical acceleration
The suspension control module evaluates these inputs in order to separately control the shock absorbers, providing an enhanced ride and comfort level over the widest possible range of operating conditions.
Circuit/System Description
The wheel speeds are detected by active wheel speed sensors. Each wheel speed sensor receives a 12 V reference voltage from the electronic brake control module (EBCM) and provides an alternating current square wave signal to the EBCM. As the wheel spins, the EBCM uses the frequency of the square wave signal to calculate the wheel speed. The EBCM sends the wheel speed information as a high speed controller area network (CAN) serial data message. Modules connected to the high speed CAN circuit monitor for the vehicle speed information.
Description and Operation
ELECTRONIC SUSPENSION CONTROL DESCRIPTION AND OPERATION
The suspension control module commands variable levels of current to each shock absorber actuator in response to rough road, braking or abrupt steering maneuver driving conditions. The current variation is performed by pulse width modulation (PWM) of the system voltage. The suspension control module continuously measures the actual current of each actuator. When a deviation between commanded and actual current is detected, a DTC is set.
ELECTRONIC SUSPENSION CONTROL DESCRIPTION AND OPERATION
The suspension control module supplies a 5 V reference voltage and a low reference to each body acceleration sensor. The body acceleration sensors supply a signal of 0.5-4.5 V to the suspension control module.
ELECTRONIC SUSPENSION CONTROL DESCRIPTION AND OPERATION
The suspension control module supplies a 5 V reference voltage and a low reference to each vertical wheel acceleration sensor. The vertical wheel acceleration sensors supply a signal of 0.5-4.5 V to the suspension control module.
ELECTRONIC SUSPENSION CONTROL DESCRIPTION AND OPERATION
The suspension control module receives high speed controller area network (CAN) message inputs from the engine control module (ECM) identifying the actual engine torque. The suspension control module utilizes this signal to control the vehicle ride characteristics.
ELECTRONIC SUSPENSION CONTROL DESCRIPTION AND OPERATION
The suspension control module supplies a 5 V reference voltage and a low reference to each body acceleration sensor and wheel acceleration sensor. The body acceleration sensors and wheel acceleration sensors supply a signal of 0.5-4.5 V to the suspension control module.
ELECTRONIC SUSPENSION CONTROL DESCRIPTION AND OPERATION
The sport mode switch, comfort mode switch and intelligent mode switch are combined into one switch module. The body control module (BCM) monitors the switch module. When a driving mode has been selected, the BCM transmits commands to the continuous damping control, steering control, four wheel drive and automatic transmission via serial data transmission in order to control the car's driving characteristics according to the selected mode. The BCM informs the driver about the selected driving mode by switching ON the appropriate LED.
TRANSMISSION SYSTEM DESCRIPTION AND OPERATION (M36 AND MXE)