|Name of part
||Outline of function
||Controls the HBB system.
|HBB buzzer and brake warning lamp
||Operates and illuminates in response to signals from the ASTC-ECU
to notify the driver of any abnormalities in the HBB system.
||The pump motor pumps up brake fluid from reservoir and charges high-pressure
brake fluid to the accumulator.
||The accumulator is pressurised with nitrogen gas and accumulates
the hydraulic pressure which is generated by the pump motor.
|Switching solenoid valve (built into hydraulic unit)
||During the ABS control, the regulator pressure is introduced to the
wheel cylinder. During the Active Stability Control/Active Traction Control, the accumulator
pressure is introduced to the wheel cylinder, increasing the pressure automatically.
|Control solenoid valve (built into hydraulic unit)
||Controls (increase, maintain, or decrease) the wheel cylinder hydraulic
pressure when ABS operates and when Active Stability Control/Active Traction Control
|Pressure switch (built into hydraulic unit)
||Two switches are included: a switch for pump control and a switch
for low-pressure warning control. The former switch outputs a pump motor drive signal when the
accumulator hydraulic pressure drops below the specified hydraulic pressure. If the accumulator
pressure drops further, the low-pressure warning control switch turns off so that a warning
lamp illumination signal and an HBB buzzer operating signal are output.
|Relief valve (built into hydraulic unit)
||This is a mechanical valve which is used to prevent excessively high
pressure from building up in the power supply system. If the pump motor keeps operating continuously
because of a problem such as a pressure switch malfunction, this valve allows excess brake fluid
to be returned to the reservoir.
||The master cylinder is a single-piston type which generates hydraulic
pressure which is transmitted to the front brakes.
||Converts the accumulator high pressure into a pressure which corresponds
to the brake pedal depression force, and transmits this to the rear brakes, and also to the
booster chamber to generate the brake assist force.
||Stores the brake fluid for the master cylinder and the power supply.
|Brake fluid level warning switch (built into reservoir)
||When the level of brake fluid inside the reservoir drops, this switch
turns on and causes the brake warning lamp to illuminate.