ABS HU PART CONSTRUCTION

id041300184300


Construction

•  The ABS HU mainly consists of the inlet/outlet solenoid valves, pump motor (pump) and reservoir tank.

Function Of Main Component Parts

Part name

Function
Inlet solenoid valve
•  Adjusts the fluid pressure in each brake system according to ABS CM signals.
Outlet solenoid valve
•  Adjusts the fluid pressure in each brake system according to ABS CM signals.
Reservoir
•  Temporarily holds the brake fluid from the caliper piston to ensure smooth pressure reduction.
Pump
•  Returns brake fluid held in the reservoir back to the master cylinder.
Pump motor
•  Operates the pump according to ABS CM signals.

Hydraulic circuit diagram

am2zzn00000383

Operation


During normal braking

•  During normal braking, the solenoid valves are not energized and they are all off. When the brake pedal is depressed, brake fluid pressure is transmitted from the master cylinder, through the inlet solenoid valves, and then to the caliper piston.(The figure shows control for only one, front wheel.)

Solenoid valve operation table

Inlet solenoid valve

Outlet solenoid valve

Pump motor, pump

LF

RF

LR

RR

LF

RF

LR

RR
OFF (open)
OFF (closed)
OFF

Hydraulic circuit diagram

am2zzn00000385


During ABS and EBD control

•  When wheel lock-up is about to occur, the inlet and outlet solenoid valves are energized and controlled in three pressure modes (increase, maintain, or reduction), thereby adjusting brake fluid pressure.Brake fluid during pressure reduction is temporarily held in the reservoir after which the pump motor operates the pump to return the fluid to the master cylinder.(The figure shows the control for only one, front wheel)

Solenoid valve operation table

 

Inlet solenoid valve

Outlet solenoid valve

Pump motor, pump

LF

RF

LR

RR

LF

RF

LR

RR
During pressure increase mode
OFF (open)
OFF (closed)
OFF
During pressure maintain mode
ON (closed)
OFF (closed)
OFF
During pressure reduction mode
ON (closed)
ON (open)
ON

Hydraulic circuit diagram

am2zzn00000386