GF27.20-P-3002N Torque Converter Lockup Clutch Control, Function

GF27.20-P-3002N Torque Converter Lockup Clutch Control, Function
TRANSMISSION 722.9 in MODEL 171.4, 203, 230 up to Model Year 2008
TRANSMISSION 722.9 in MODEL 209, 211, 215, 219, 220
TRANSMISSION 722.9 in MODEL 463.303 /340 /341 up to 31.5.12

The clutch pressure in the torque converter lockup clutch is derived from the working pressure through the torque converter lockup clutch regulating valve. The regulating valve position is influenced by the torque converter lockup clutch control solenoid valve (VGS) (Y3/8y8). The clutch pressure in the torque converter lockup clutch depends on the regulating valve position and thus on the geometry of the torque converter lockup clutch regulating valve. The torque converter lockup clutch has the following control states:
^ Open
^ open-slipping
^ SLIPPING
^ slipping-open

"Open" control state"
The regulating valve of the torque converter lockup clutch is located in the basic position. The working pressure acts on the converter regulating valve via a connecting line between the torque converter lockup clutch regulating valve and the converter regulating valve. Lubrication pressure is applied to the converter as a result. The torque converter lockup clutch is in the unpressurized condition.

Control state "open-slipping"
The torque converter lockup clutch regulating valve is no longer in the basic position and as a result interrupts the connection between the torque converter lockup clutch regulating valve and the converter regulating valve. The torque converter lockup clutch is filled.

Control state "slipping"
The required slip (specified slip) is stored in the fully integrated transmission control (VGS) control unit (Y3/8n4). The fully integrated transmission control (VGS) control unit (Y3/8n4) calculates the required control current and actuates the torque converter lockup clutch control solenoid valve (VGS) (Y3/8y8) which influences the position of the torque converter lockup clutch regulating valve (pre-control). The clutch pressure in the torque converter lockup clutch depends on the regulating valve position and thus on the regulating valve geometry. The actual slip is determined by the comparison of engine speed with the turbine speed. If necessary, a post-regulation is introduced by the fully integrated transmission control (VGS) control unit (Y3/8n4). The clutch pressure in the torque converter lockup clutch can be increased or reduced by post-regulation.

Control state "slipping-open"
In this control state the clutch pressure in the torque converter lockup clutch is reduced in stages. In this process a constantly progressive operation is involved which is moved along a time ramp from the initial value to zero until the clutch pressure in the torque converter lockup clutch is reduced.

The torque converter lockup clutch is not actuated in limp- home mode.