Gear change, function

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Power flow diagram when driving

1 Flywheel

2 Dry clutch

3 Vibration damper

4 Hollow shaft

5 Turbo clutch

6 Impeller

7 Turbine wheel

8 Turbine wheel brake

9 Brake roller freewheel

10 Transmission input shaft

Driving function

When driving the power flow is always generated by way of the dry clutch (2) straight onto the transmission input shaft (10), the turbo clutch (5) acts passively.

To lubricate the turbo clutch (5), the dry clutch control unit (TK) (A125) sends a signal at timed intervals and dependent on the driving condition to the proportional valve (Y151), this in turn enables a small quantity of oil to enter the turbo clutch's working chamber (5) and into the turbine wheel (8) brake disks for lubrication purposes.

Gear change function

During a gear change, the dry clutch (2) is operated by the clutch actuator.

The turbo clutch control unit (TK) (A125) uses the turbine wheel rpm sensor (B189) to determine whether the turbine wheel is turning and briefly activates, if necessary, the turbine wheel brake (8), to ensure that the turbine wheel (7) is reliably decoupled from the transmission input shaft (10). This in turn ensures that the gear change in the transmission is not impaired by any turbine wheel (7) inertia or by any residual torque.

W25.50-1024-79

6 Impeller

7 Turbine wheel

8 Turbine wheel brake

9 Brake roller freewheel

11 Oil separator

12 Shaped breather

13 Check valve

14 Quick drain valve

15 Heat exchanger

16 Outlet restrictor

17 Outlet check valve

18 Inlet check valve

19 Air restrictor

20 Oil supply chamber

D Coolant circuit

F Compressed air supply

G Unpressurized line

a Ancillary consumer circuit

A3 Vehicle engine control (FMR) control unit

A125 Turbo clutch (TK) control unit

B187 Oil reservoir pressure sensor

B188 Ventilation pressure sensor

B189 Turbine wheel rpm sensor

B190 Oil temperature sensor

B191 Coolant temperature sensor

CAN 1 Vehicle CAN

Y151 Proportioning valve

Y152 Fast emptying solenoid valve

Y153 Turbine wheel brake solenoid valve

Actuation process

To ensure that the gear change is not impaired, the turbine wheel (7) speed must be lower than the transmission input shaft (10) speed. If this is not the case, the speed of the turbine wheel (7) is reduced using the turbine wheel brake (8).

To this end, the turbine wheel brake solenoid valve (Y153) is actuated and reservoir pressure applied to the turbine wheel brake (8) piston.

To switch off the turbine wheel brake (8) the turbine wheel brake solenoid valve (Y153) actuation is interrupted and the reservoir pressure escapes into the atmosphere through the turbine wheel brake (8) piston.

The turbine wheel rpm sensor (B189) enables the turbo clutch control unit (TK) (A125) to recognize that the speed of the turbine wheel (7) is below the speed of the transmission input shaft (10) and the gear change can then be made smoothly in the transmission.