System Description

SYSTEM

System Description

- The system switches fluid pressure of each brake caliper to increase, to hold or to decrease according to signals from control unit in ABS actuator and electric unit (control unit). This control system is applied to
VDC function, TCS function, ABS function, EBD function, brake limited slip differential (BLSD) function, brake assist function and Brake force distribution function.
- If a malfunction occurs in the electrically-driven intelligent brake unit, the VDC function performs control (boost operation).
- Fail-safe function is available for each function and is activated by each function when system malfunction occurs.

SYSTEM DIAGRAM







INPUT SIGNAL AND OUTPUT SIGNAL

Major signal transmission between each unit via communication lines is shown in the following table.






*: Communication line between yaw rate/side/decel G sensor and ABS actuator and electric unit (control unit)

VALVE OPERATION (ABS AND EBD)

Each valve is operated and fluid pressure of brake caliper is controlled.
When ordinary brake is applied










- When the cut valve 1 and the ABS IN valve opens, brake fluid is supplied to the front RH brake caliper from the electrically-driven intelligent brake unit through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.
- When the cut valve 2 and the ABS IN valve opens, brake fluid is supplied to the front LH brake caliper from the electrically-driven intelligent brake unit through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.
- When the cut valve 2 and the ABS IN valve opens, brake fluid is supplied to the rear RH brake caliper from the electrically-driven intelligent brake unit through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.
- When the cut valve 1 and the ABS IN valve opens, brake fluid is supplied to the rear LH brake caliper from the electrically-driven intelligent brake unit through the ABS IN valve. Brake fluid does not flow into the reservoir because the ABS OUT valve is closed.
ABS is in operation (when pressure increases)










- Brake fluid is supplied to the front RH brake caliper from the electrically-driven intelligent brake unit through the cut valve 1 and the ABS IN valve. Since the suction valve 1 and the ABS OUT valve is closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the front RH brake caliper from the electrically-driven intelligent brake unit is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).
- Brake fluid is supplied to the front RH brake caliper from the electrically-driven intelligent brake unit through the cut valve 2 and the ABS IN valve. Since the suction valve 2 and the ABS OUT valve is closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the front LH brake caliper from the electrically-driven intelligent brake unit is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).
- Brake fluid is supplied to the front RH brake caliper from the electrically-driven intelligent brake unit through the cut valve 2 and the ABS IN valve. Since the suction valve 2 and the ABS OUT valve is closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the rear RH brake caliper from the electrically-driven intelligent brake unit is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).
- Brake fluid is supplied to the front RH brake caliper from the electrically-driven intelligent brake unit through the cut valve 1 and the ABS IN valve. Since the suction valve 1 and the ABS OUT valve is closed, the fluid does not flow into the reservoir. The amount of brake fluid supplied to the rear LH brake caliper from the electrically-driven intelligent brake unit is controlled according to time that the ABS IN valve is not energized (time that the ABS IN valve is open).
When ABS operation (when pressure holds)











- Since the ABS IN valve and the ABS OUT valve are closed, the front RH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the front RH brake caliper.
- Since the ABS IN valve and the ABS OUT valve are closed, the front LH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the front RH brake caliper.
- Since the ABS IN valve and the ABS OUT valve are closed, the rear RH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the front RH brake caliper.
- Since the ABS IN valve and the ABS OUT valve are closed, the rear LH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the front RH brake caliper.
ABS is in operation (when pressure decreases)











- Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the front RH
brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the electrically-driven intelligent brake unit by the pump.
- Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the front LH
brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the electrically-driven intelligent brake unit by the pump.
- Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the rear RH
brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the electrically-driven intelligent brake unit by the pump.
- Since the ABS IN valve is closed and the ABS OUT valve is opened, fluid pressure applied on the rear LH
brake caliper is supplied to the reservoir through the ABS OUT valve. This fluid pressure decreases when sent to the electrically-driven intelligent brake unit by the pump.
Released











- Brake fluid is supplied to the front RH caliper through the return check valve of the ABS IN valve and the cut valve 1, and returns to the electrically-driven intelligent brake unit.
- Brake fluid is supplied to the front LH caliper through the return check valve of the ABS IN valve and the cut valve 2, and returns to the electrically-driven intelligent brake unit.
- Brake fluid is supplied to the rear RH caliper through the return check valve of the ABS IN valve and the cut valve 2, and returns to the electrically-driven intelligent brake unit.
- Brake fluid is supplied to the rear LH caliper through the return check valve of the ABS IN valve and the cut valve 1, and returns to the electrically-driven intelligent brake unit.
Component Parts and Function






VALVE OPERATION (OTHER THAN ABS AND EBD)

Each valve is operated and fluid pressure of brake caliper is controlled.
When Pressure Increases










- Brake fluid is conveyed to the pump from the electrically-driven intelligent brake unit through suction valve 1
and is pressurized by the pump operation. The pressurized brake fluid is supplied to the front RH brake caliper through the ABS IN valve. For the left caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the left caliper is controlled separately from the right caliper.
- Brake fluid is conveyed to the pump from the electrically-driven intelligent brake unit through suction valve 2
and is pressurized by the pump operation. The pressurized brake fluid is supplied to the front LH brake caliper through the ABS IN valve. For the left caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the right caliper is controlled separately from the left caliper.
- Brake fluid is conveyed to the pump from the electrically-driven intelligent brake unit through suction valve 2
and is pressurized by the pump operation. The pressurized brake fluid is supplied to the rear RH brake caliper through the ABS IN valve. For the left caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the left caliper is controlled separately from the right caliper.
- Brake fluid is conveyed to the pump from the electrically-driven intelligent brake unit through suction valve 1
and is pressurized by the pump operation. The pressurized brake fluid is supplied to the rear LH brake caliper through the ABS IN valve. For the left caliper, brake fluid pressure is maintained because the pressurization is unnecessary. The pressurization for the right caliper is controlled separately from the left caliper.
When pressure holds










- Since the cut valve 1 and the suction valve 1 are closed, the front RH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the front RH brake caliper. The pressurization for the left caliper is controlled separately from the right caliper.
- Since the cut valve 2 and the suction valve 2 are closed, the front LH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the front LH brake caliper. The pressurization for the left caliper is controlled separately from the left caliper.
- Since the cut valve 2 and the suction valve 2 are closed, the rear RH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the rear RH brake caliper. The pressurization for the left caliper is controlled separately from the right caliper.
- Since the cut valve 1 and the suction valve 1 are closed, the rear LH brake caliper, electrically-driven intelligent brake unit, and reservoir are blocked. This maintains fluid pressure applied on the rear LH brake caliper. The pressurization for the left caliper is controlled separately from the left caliper.
When pressure decreases










- Since the suction valve 1 and the ABS OUT valve close and the cut valve 1 and the ABS IN valve open, the fluid pressure applied on the front RH brake caliper is reduced by supplying the fluid pressure to the electrically-driven intelligent brake unit via the ABS IN valve and the cut valve 1. The pressurization for the right caliper is controlled separately from the left caliper.
- Since the suction valve 2 and the ABS OUT valve close and the cut valve 2 and the ABS IN valve open, the fluid pressure applied on the front LH brake caliper is reduced by supplying the fluid pressure to the electrically-driven intelligent brake unit via the ABS IN valve and the cut valve 2. The pressurization for the left caliper is controlled separately from the right caliper.
- Since the suction valve 2 and the ABS OUT valve close and the cut valve 2 and the ABS IN valve open, the fluid pressure applied on the rear RH brake caliper is reduced by supplying the fluid pressure to the electrically-driven intelligent brake unit via the ABS IN valve and the cut valve 2. The pressurization for the right caliper is controlled separately from the left caliper.
- Since the suction valve 1 and the ABS OUT valve close and the cut valve 1 and the ABS IN valve open, the fluid pressure applied on the rear LH brake caliper is reduced by supplying the fluid pressure to the electrically-driven intelligent brake unit via the ABS IN valve and the cut valve 1. The pressurization for the left caliper is controlled separately from the right caliper.
Component Parts and Function






CONDITION FOR TURN ON THE WARNING LAMP

ABS Warning Lamp
- Turns ON at the same time as VDC warning lamp when either ABS function or EBD function is malfunctioning.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.





Brake Warning Lamp
- Turns ON at the same time as ABS warning lamp and VDC warning lamp when EBD function is malfunctioning.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.






VDC Warning Lamp
- Turns ON when either VDC function, TCS function, ABS function, EBD function, brake limited slip differential (BLSD) function, brake assist function or Brake force distribution function are malfunctioning.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.






CONDITION FOR TURN ON THE INDICATOR LAMP

VDC OFF indicator lamp
- Turns ON when VDC function and TCS function are switched to non-operational status (OFF) by VDC OFF
switch.
- Turns ON when ignition switch turns ON and turns OFF when the system is normal, for bulb check purposes.