MECHATRONIC Valve Block
| ITEM | DESCRIPTION |
|---|---|
| 1 | Electronic Pressure Regulating Solenoid (EPRS) A - A brake valve |
| 2 | Electronic Pressure Regulating Solenoid (EPRS) D - D clutch valve |
| 3 | Electronic Pressure Regulating Solenoid (EPRS) B - B brake valve |
| 4 | Electronic Pressure Regulating Solenoid (EPRS) E - E clutch valve |
| 5 | Magnet valve 2 - For electrical park interlock (hold out of park) |
| 6 | Magnet valve 1 - Pressure reducing valve |
| 7 | Electronic Pressure Regulating Solenoid (EPRS) SYS - system pressure valve |
| 8 | Electronic Pressure Regulating Solenoid (EPRS) WK - Torque converter lock-up clutch valve |
| 9 | Electronic Pressure Regulating Solenoid (EPRS) C - C clutch valve |
| 10 | Transmission output shaft speed sensor |
| 11 | Electrical connector |
| 12 | Transmission Control Module (TCM) - hidden |
The mechatronic valve block is located in the bottom of the transmission and is covered by the fluid pan. The valve block houses the Transmission Control Module (TCM), electrical actuators, speed sensors and control valves which provide all electro-hydraulic control for all transmission functions.
The mechatronic valve block comprises the following components:
- Transmission Control Module (TCM)
- Seven pressure regulator solenoids
- Two park lock solenoids
- 21 hydraulic spool valves
- Temperature sensor
- Turbine speed sensor
- Output shaft speed sensor.
Electronic Pressure Regulator Solenoids
Seven Electronic Pressure Regulator Solenoids (EPRS) are located in the valve block. The solenoids are controlled by Pulse Width Modulation (PWM) signals from the Transmission Control Module (TCM). The solenoids convert the electrical signals into hydraulic control pressure proportional to the signal to actuate the spool valves for precise transmission operation.
Solenoids EPRS A, B, D, E and WK supply a higher control pressure as the signal amperage increases and can be identified by an orange connector cap. The TCM operates the solenoids using PWM signals. The TCM monitors engine load and clutch slip and varies the solenoid duty cycle accordingly. The solenoids have a 12V operating voltage and a pressure range of 0 - 4.7 bar (0 - 68 lbf.in2 ).
Solenoids EPRS C and SYS supply a lower control pressure as the signal amperage increases and can be identified by a gray connector cap. The TCM monitors engine load and clutch slip and varies the solenoid duty cycle accordingly. The solenoids have a 12V operating voltage and a pressure range of 4.7 - 0 bar (68 - 0 lbf.in2 ).
The resistance of the solenoid coil winding for EPRS solenoids is 5.05 Ohms at 20°C (68°F).
Control Solenoid (MV1)
A shift control solenoid Magnetic Valve 1 (MV1) is located in the valve block. The solenoid is controlled by the Transmission Control Module (TCM) and converts electrical signals into hydraulic control signals to control clutch application.
The shift control solenoid is an open/closed, on/off solenoid which is controlled by the TCM switching the solenoid to earth. The TCM also supplies power to the solenoid. The TCM energizes the solenoid in a programmed sequence for clutch application for gear ratio changes and shift control.
The resistance of the solenoid coil winding for solenoid is between 10 to 11 Ohms at 20°C (68°F).
Control Solenoid (MV2)
| ITEM | DESCRIPTION |
|---|---|
| A | Solenoid in locked (energized) condition - park lock released |
| B | Solenoid in unlocked (de-energized) condition - park lock engaged |
| 1 | Solenoid |
| 2 | Claw - locked |
| 3 | Piston |
| 4 | Claw - unlocked |
A control solenoid Magnetic Valve 2 (MV2) is located in the valve block. The solenoid is controlled by the Transmission Control Module (TCM) and converts electrical signals into hydraulic control signals to control the electronic park lock function.
The control solenoid is an on/off solenoid which is controlled by the TCM by switching the solenoid to ground.
When the park position is deselected, control solenoid MV2 resets the parking lock valve in the mechatronic valve block. This is achieved by the TCM providing the ground for the solenoid which is energized, releasing the claws from retaining the park lock piston. Main fluid pressure acting on the parking lock piston, pushes the piston back to release the lock.
When the park position is selected, control solenoid MV2 is de-energized. The fluid pressure at the parking lock cylinder piston is vented and the mechanical interlock of the piston is opened. A pre-tensioned torsion spring at the park lock disc pulls the piston into the Park (P) position where the piston engages with the control solenoid claws and is locked in the park position. The Emergency Park Release (EPR) mechanism can be used to release the parking lock manually if an electrical failure occurs.
The resistance of the solenoid coil winding for solenoid is 25 Ohms at 20°C (68°F).
When the Neutral (N) position is selected and the engine is not running, the fluid pressure at the park lock cylinder piston is released. The current supply to the control solenoid MV2 remains. The park lock cylinder piston is still held in the unlocked position by the spring force acting on the park lock disc, preventing the park lock plate from engaging the parking lock. This allows the vehicle to be moved when the engine is not running for a short time. Should the battery voltage fall below the level required to maintain the solenoid in the energized condition, the park lock will be engaged.
Speed Sensors
The turbine speed sensor and the output shaft speed sensor are Hall effect type sensors located in the mechatronic valve block and are not serviceable items. The Transmission Control Module (TCM) monitors the signals from each sensor to determine the input (turbine) speed and the output shaft speed.
The turbine speed is monitored by the TCM to calculate the slip of the torque converter clutch and internal clutch slip. This signal allows the TCM to accurately control the slip timing during shifts and adjust clutch application or release pressure for overlap shift control.
The output shaft speed is monitored by the TCM and compared to engine speed signals received on the FlexRay bus from the Powertrain Control Module (PCM). Using a comparison of the two signals the TCM calculates the transmission slip ratio for plausibility and maintains adaptive pressure control.
Temperature Sensor
The temperature sensor is also located in the mechatronic valve block. The Transmission Control Module (TCM) uses the temperature sensor signals to determine the temperature of the Automatic Transmission Fluid (ATF). These signals are used by the TCM to control the transmission operation to promote faster warm-up in cold conditions or to assist with fluid cooling by controlling the transmission operation when high fluid temperatures are experienced. If the sensor fails, the TCM will use a default value and a Diagnostic Trouble Code (DTC) will be stored in the TCM.
Spool Valves
The mechatronic valve block contains spool valves which control various functions of the transmission. The spool valves are of conventional design and are operated by fluid pressure.
Each spool valve is located in its spool bore and held in a default (unpressurized) position by a spring. The spool bore has a number of ports which allow fluid to flow to other valves and clutches to enable transmission operation. Each spool has a piston which is waisted to allow fluid to be diverted into the applicable ports when the valve is operated.
When fluid pressure moves a spool, one or more ports in the spool bore are covered or uncovered. Fluid is prevented from flowing or is allowed to flow around the applicable waisted area of the spool and into another uncovered port. The fluid is either passed through galleries to actuate another spool, operate a clutch or is returned to the fluid pan.