ETS control mode, function - GF42.35-P-3500V
MODEL 210.08 /28, 220.08 /18 with CODE (472a) Electronic Stability Program (ESP)
ETS pressure build-up control mode
The control procedure and valve positions shown in the example relate to the right front brake.
If one of the drive wheels begins to spin when the vehicle is starting off or accelerating, the control module initiates the ETS pressure build-up control mode.
At the start of the ETS control the switchover solenoid valves (y18, y19) are switched to the "lock position" (closed) and the self-induced high pressure and return pumps (p1, p2) are actuated.
The inlet solenoid valve (y22) is controlled in different ways according to the pressure in the brake calipers:
- If a pressure of ≤ 60 bar is reached in the brake calipers the inlet solenoid valve (y22) is only opened during the pressure build-up phases. The self-induced high-pressure and return pump (p1) draws brake fluid out of the reservoir via the inlet solenoid (y22) and master brake cylinder.
- If a pressure > 60 bar is reached in one of the brake calipers, the inlet solenoid valve (y22) remains open during the entire control phase.
The pressure for the right front brake caliper (5a) is build-up by the self-induced high pressure and return pump (p1) via the solenoid valve (y8; not actuated - open).
The high pressure is limited by the pressure limiting valve (approx. 170 bar) integrated in the switchover solenoid valve (y18).
ETS pressure holding control mode
The control procedure and valve positions shown in the example relate to the right front brake with a brake pressure > 60 bar in the brake caliper.
If more intensive braking control is no longer required for preventing the wheel slip, the ETS pressure holding control mode then commences.
If a pressure of ≤ 60 bar is reached in the brake caliper the inlet solenoid valve (y22) is closed. Thus the pressure in the brake caliper cannot be increased via the high pressure and return pump (p1).
If a brake pressure > 60 bar is reached in the brake caliper the pressure holding phase is initiated by actuating (closing) the solenoid valve (y8). In this control phase, the solenoid valves (y8 and y9) are closed and the pressure in the brake caliper thus remains constant. The self-induced high pressure and return pump (p1) is also actuated in this control phase and the switchover solenoid valves (y18 and y19) are closed. The excess pressure created between the high pressure and return pump (p1) and switchover solenoid valve (y18) is reduced by the pressure limiting valve integrated in the switchover solenoid valve.
ETS pressure reduction control mode
The control procedure and valve positions shown in the example relate to the right front brake with a brake pressure in the brake caliper > 60 bar.
If the braking pressure required for preventing the wheel slip is too high, the ETS pressure reduction control mode then commences.
If the pressure in the brake caliper is > 60 bar the pressure reduction phase is initiated by actuating (opening) the solenoid valve (y9). The solenoid (y8) remains closed. The returning brake fluid flows back to the brake fluid reservoir partially through the inlet solenoid valve (y22), partially via the high pressure and return pump (p1) and the pressure limiting valve integrated in the switchover solenoid valve (y18) via the master brake cylinder.
If a pressure of ≤ 60 bar is reached in the brake caliper the pressure reduction phase is initiated by opening the switchover solenoid valve (y18). The solenoid valve (y8) remains open and the solenoid valve (y9) remains closed.
The high pressure and return pump (p1) pumps the backflowing brake fluid through the switchover solenoid valve (y18), and then through the master brake cylinder back to the brake fluid reservoir.
The self-induced high pressure and return pump (p1) is also actuated in these control phases.
ETS pressure build-up control module at one rear wheel
ETS pressure build-up at both rear wheels
ETS pressure build-up at both rear wheels and at one front wheel
ETS pressure build-up at left rear and pressure holding at right rear and left front
(Example: calculated brake pressure in left front brake caliper < 60 bar)
ETS pressure build-up at left rear, pressure reduction at right rear and pressure holding at left front
(Example: calculated brake pressure in brake caliper < 60 bar)
| Location / task / design / function of ESP hydraulic unit | GF42.50-P-4000B | ||
| Location / task / function of ESP control module | GF42.45-P-4500V |