Automatic Dual Clutch Transaxle (Dct) Powershift (DPS6/6DCT250): Adjustments Ford Focus III

Double clutch with travel-controlled wear adjustment

As a result of wear to the clutch discs, the positions of the lever springs change, and this in turn alters the characteristic curves of the contact pressure and disengaging force. The consequence of this would be increased loads on the brushless DC motors of the electromechanical lever actuators.

In order to keep the position of the lever springs and therefore the contact pressure and disengaging force more or less constant, the double clutch has a travel-controlled wear adjustment mechanism.

It comprises the following main components

1. Clutch cover with adjusting and sensing ramps
2. Adjustment ramp ring for each partial clutch
3. Ramp ring for each partial clutch
4. Clamping springs, adjustment tension springs and adjustment roller springs for each partial clutch.

Scheme 22

The adjustment of the clutch is triggered if - as a result of wear to the clutch lining - the lever spring for generating a specific contact pressure is pressed through further in the direction towards the engine. As a result of the additional travel, the clamping spring lifts off the ramp ring. As a result of the pre-loaded adjustment roller spring, the ramp ring is rotated on the ramp until the clearance between the clamping spring and the ramp ring has been compensated for. If the clutch is then fully opened (i.e. disengaged) again as a result of a gearshift process, the lever spring moves into a new position due to the rotation of the ramp ring, and this creates an air gap between the lever spring and the adjustment ramp ring. As a result of the adjustment ramp ring, which is also spring-loaded, it is then rotated until it abuts against the lever spring. The adjustment process is then complete.

Scheme 23

Scheme 24

The ISS sensor 1 is attached to the transmission housing. The spacer washer provides a defined distance between the sensor and the transmitter wheel. The spacer washer has a thickness of 3.5 mm ± 0.05 mm.

The sensor detects the rotational speed via the third gear wheel of the input shaft (core shaft (odd gears)). It is a magneto-resistive sensor which measures the rotational speed and the direction of rotation. The signal is processed via internal electronics and forwarded to the TCM.

Scheme 25

The ISS sensor 2 is attached to the transmission housing. The spacer washer provides a defined distance between the sensor and the transmitter wheel. The spacer washer has a thickness of 3.2 mm ± 0.05 mm.

The sensor detects the rotational speed via the fourth gear wheel of the input shaft (hollow shaft (even gears)). It is a magneto-resistive sensor which only measures the rotational speed. The signal is processed via internal electronics and forwarded to the TCM.

Scheme 26

The OSS sensor is attached to the transmission housing.

The sensor detects the rotational speed via a transmitter wheel which is attached to the differential. It is a magneto-resistive sensor which only measures the rotational speed. The rotational speed signal is processed via internal electronics and forwarded to the TCM.

Scheme 27

The TR sensor is attached to the transmission housing. A cover plate is attached to the actuation shaft on both sides of the TR sensor. Operation of the selector lever rotates the shaft and therefore also the cover plate.

The TR sensor is a double contactless inductive sensor. It functions essentially in a similar way to a transformer. First, the incoming DC voltage is converted into AC voltage. The cover plates are moved when the selector lever is moved. This causes the magnetic fields to change and the induced AC voltages in the secondary coils therefore also change. These voltage changes are evaluated in the integrated electronics and converted into two digital signals (PWM signals).

The TR sensor is hard-wired to the TCM. On the basis of the two PWM signals, the TCM detects the position of the selector lever.

Scheme 28

All electric motors are designed as brushless DC motors.

Scheme 29

The stator coils are actuated by the electronics in the TCM in such a way that a circumferential magnetic field is generated. The rotor runs behind the magnetic field. Via the Hall sensors, the TCM receives information on the position of the rotor and calculates by how many rotations the motor has been turned. This information is required by the TCM to actuate the shift forks in accordance with the specified torque angle and to actuate the clutches. A detailed description of the function of the brushless DC motor can be found in the e-Learning module "Sensors and Actuators" (TC 401 2071C).