Vacuum supply, function - GF42.22-P-1004FLH

MODEL 212.095/098/298 

Function requirements for vacuum supply in general 

• Regenerative braking system control unit (N30/6) activated through wake-up function

Vacuum supply, general 

The vacuum supply for the BAS brake booster (A7/7) is supported by the vacuum pump (M56).

Vacuum supply function sequence 

The regenerative braking system control unit evaluates the brake vacuum sensor (B64/1) signal, which measures the vacuum in the BAS brake booster's vacuum chamber.

If the vacuum in the BAS brake booster is too low, the regenerative braking system control unit actuates the vacuum pump through the vacuum pump relay (+) (K109) and vacuum pump (-) relay (K109/1). If the regenerative braking system control unit has been activated through the wake-up function, then the vacuum pump relay (-) is switched on. The vacuum pump relay (+) is only activated at a low vacuum in the BAS brake booster by the regenerative braking system control unit.

As soon as the vacuum, measured by the brake vacuum sensor and assessed by the regenerative braking system control unit, reaches the cutoff value, the vacuum pump relay (+) and therefore the electrical vacuum pump are switched off.

Vacuum pump relay (+)

The vacuum pump relay (+) is designed as a solid-state relay, to achieve a faster response time and higher switching frequency. The difference to the vacuum pump relay (-) lies in the fact that mechanical parts are no longer used. A feedback line on the relay output is used by the regenerative braking system control unit to monitor the function of the vacuum pump relay (+).