Part 2

Mechanical Component Description

General Description

The MVA automatic transaxle is used with the 2.4L engine models with AWD. This automatic transaxle is a compact and high-capacity 4-speed Super Electronic Controlled Transaxle. A low-viscosity type transmission fluid is used. For further details, refer to the owners manual.





Component Identification









Torque Converter

The torque converter has optimally designed fluid passages and impeller configuration, resulting in substantially enhanced transmission efficiency to ensure good starting, acceleration and fuel economy. Furthermore, a hydraulically operated lock-up mechanism which cuts power transmission losses due to slippage at medium and high speeds is used









Fluid Pump





The fluid pump is combined torque converter, lubricates the planetary gear units and supplies operating pressure to the hydraulic control.





Valve Unit Body

The valve body consists of the upper and lower valve bodies and 5 solenoid valves. Apply orifice control, which controls the flow volume to the B3 brake, is used.

Solenoids





Upper Valve Body - MVA





Lower Valve Body - MVA





Centrifugal Fluid Pressure Cancelling Mechanism

There are two reasons for improving the conventional clutch mechanism:

* To prevent the generation of pressure by the centrifugal force that is applied to the fluid in piston fluid pressure chamber (hereafter referred to as "chamber A") when the clutch is released, a check ball is provided to discharge the fluid. Therefore, before the clutch can be subsequently applied, it takes time for the fluid to fill the chamber A.
* During shifting, in addition to the original clutch pressure that is controlled by the valve body, the pressure that acts on the fluid in the chamber A also exerts influence, which is dependent upon revolution fluctuations.





To address these two needs for improvement, a canceling fluid pressure chamber (hereafter referred to as "chamber B") has been provided opposite chamber A.





By utilizing the lubrication fluid such as that of the shaft, the same amount of centrifugal force is applied, thus canceling the centrifugal force that is applied to the piston itself. Accordingly, it is not necessary to discharge the fluid through the use of a check ball, and a highly responsive and smooth shifting characteristic has been achieved.

Shift Control Mechanism





A gate type shift lever is used in conjunction with the 4-speed automatic transaxle. With the gate type lever, the shift lever button and the release switch of the straight type (L gate type) shift lever are discontinued. Similar functions are achieved through a single-shift operation (fore-aft and side-to-side). For the shift lever for the multi-mode automatic transmission, an S mode position is provided next to the D position. The shift lever can be moved, park through drive, only with the ignition switch in the ON position and the brake pedal depressed. Once into the S position, the shift lever can be moved anytime.

Shift Lock System
* The shift lock mechanism prevents the shift lever from being moved to a position other that the P position, unless the ignition switch is turned ON and the brake pedal is depressed. It prevents the vehicle from starting off suddenly.
* The key interlock device prevents the key from being pulled out after the ignition switch is turned OFF, unless the shift lever is moved to the P position. Thus, the driver is urged to park the vehicle in the P position.
* The shift lock system mainly consists of the shift lock ECU, shift lock solenoid, key interlock solenoid and shift lock release button.
* The shift lock solenoid has a built-in P detection switch.

Shift Lock System Components





Key Interlock Solenoid

The activation of the key interlock solenoid that is mounted on the upper column bracket moves the lock pin to restrict the movement of the key cylinder. Therefore, if the shift lever is moved to any position other than P, the ignition key cannot be moved from the ACC to the LOCK position.

System Operation




* The shift lock ECU uses the P detection switch to detect the shift lever position, and receives input signals from the stop light switch and ignition switch. Upon receiving these signals, the shift lock ECU turns ON the key interlock solenoid and the shift lock solenoid in order to release the key interlock and shift lock
* A shift lock release button, which manually releases the shift lock mechanism, is used.

Planetary Gear Unit

Construction

The counter drive and driven gears are placed in front of the front planetary gear and under drive (U/D) planetary gear unit is placed above the counter shaft. Furthermore, the number of the brake and one-way clutch is minimized to realize the compact and high-capacity structure. A centrifugal fluid pressure canceling mechanism is used in the C2 and C3 clutches that are applied when shifting from 2nd to 3rd and from 3rd to 4th.

Component ID and Function