Suspension Control ( Automatic - Electronic ): Description and Operation

This system consists of a pneumatic cylinder which has pressured air in an air chamber, an ECU which automatically switches vehicle height between two ranges (Normal and high) according to the driving conditions and also two (2) modes (Normal and high) which the driver can choose from according to preference.

Also, the damping force of the shock absorber is automatically switched by the ECU among nine levels (soft to hard). Combined control of vehicle height and damping force suppresses changes in the vehicle's attitude such as roll, nose dive and squat to provide outstanding riding comfort and controllability.

1. INPUT SIGNALS
1. Steering sensor signal
Rotation angle of the steering wheel is input to TERMINALS SS1 and SS2 of the air suspension ECU.
2. Throttle position sensor signal
The throttle valve opening angle is detected and the signal is input to TERMINAL L1 of the air suspension ECU via the engine control module.
3. Vehicle speed sensor signal
The vehicle speed is detected by the vehicle speed sensor and the signal is input to TERMINAL SPD of the air suspension ECU.
4. Stop light SW signal
The brake operation signal is detected and the signal is input to TERMINAL STP of the air suspension ECU.
5. Height control SW signal
Whether the height control SW is in normal or high mode is detected and the signal is input to TERMINAL HSW of the air suspension ECU.
6. Height control sensor signal
The vehicle height and the different levels of the road surface are detected by the height control sensor and the signal is input to TERMINALS SHFL, SHFR, SHRL and SHRR of the air suspension ECU.
7. Door courtesy SW signal
Whether the door is open or closed is detected and input to TERMINAL DOOR of the air suspension ECU.

2. AIR SUSPENSION OPERATION
* High position
Signals from the vehicle speed sensor, height control sensor and so on are input to the air suspension ECU, which operates so that the current flows from the air suspension ECU to front and rear height control valve to open the pneumatic cylinder valve.

As a result, the passage is opened as far as the height control dryer. Then, the current flowing to the AIR SUS relay flows to the height control compressor. Control of this current by the air suspension ECU causes the compressor to operate and air flows into the pneumatic cylinder to raise the vehicle height.

* Low position
Signals from the vehicle speed sensor, height control sensor and so on are input to the air suspension ECU, which operates so that current flows from the air suspension ECU to front and rear height control valve to open the pneumatic cylinder valve.

As a result, the passage is opened as far as the height control dryer. Then, the current flows to the height control exhaust valve installed in the height control dryer. Control of this current by the air suspension ECU causes the valve to open so that the air inside the pneumatic cylinder is expelled and the vehicle height is lowered.

3. BASIC OPERATION OF SUSPENSION CONTROL ACTUATOR
The suspension control actuator controls the damping force of the shock absorber inside the pneumatic cylinder in 9 steps. Based on signals from the acceleration sensors, vehicle speed sensor and stop light switch, etc., the suspension ECU controls the suspension control actuator to adjust the damping force of the shock absorber.




As the table shows, the damping force of the shock absorber is changed by the current flowing from TERMINAL 2, 3, 4 and 5 of the suspension control actuators to TERMINAL 1 to GROUND.