ETS Hydraulic Unit, Function

ETS Hydraulic Unit, Function










All switching components of the ABS and ETS systems are combined in the ETS hydraulic unit (A7/3).

A 2/2-way valve for build-up/hold pressure or hold/release pressure functions is used on each wheel for control. The self-priming high pressure/return pumps (p1, p2) integrated in the hydraulic unit (A7/3) are used to supply pressure to the ETS and return the brake fluid for ABS control. The inlet pipes of the self-priming high pressure/return pumps (p1, p2) contain the inlet solenoid valves (y26, y27).

The inlet solenoid valves (y26, y27) are opened only once a pressure of > 60 bar has been reached in the respective brake calipers during the ETS pressure build-up phase. They are opened for the time it takes to actuate solenoid valves (y6, y8, y10 or y12).

When pressures of > 60 bar are reached in one of the respective brake calipers during ETS control, the inlet solenoid valves (y26, y27) remain open.

During ETS control, the switchover solenoid valves (y24 , y25) lock the front and rear axle circuits 1 (VL and HR) and 2 (VR and HL) to the brake master cylinder. They are also designed to function as a pressure relief valve and open at approx. 150 bar.

A muffler (10) Is fitted for each brake circuit to reduce delivery noise. During the ABS pressure reduction phase the fluid flows back to the high-pressure/return pump via the low-pressure accumulator (11).