Automatic Transmission/Transaxle: Description and Operation
DESCRIPTIONGeneral Description
The A241E and A244E are 4-speed Electronically Controlled Transaxles. They feature a lockup mechanism developed exclusively for use with transversely mounted engines. They have the following additional features.
- The "Super-Flow" torque converter clutch improves transaxle efficiency.
- The transaxle control ECM has been integrated with the ECM.
- To reduce transaxle shift shock, ECM control at the shift point reduces engine torque and the clutch hydraulic pressure.
The automatic transaxle is mainly composed of the torque converter clutch with lock -up clutch, 4-speed planetary gear unit, hydraulic control system and an electronic control system. To minimize the possibility of incorrect operation of the automatic transaxle, a shift lock mechanism has also been added.
General Specifications
OPERATION
1. Function Of Components
2. Hydraulic Control System
The hydraulic control system is composed of the oil pump, the valve body, the solenoid valves, the accumulators, the clutches and brakes as well as the fluid passages which connect all of these components.
Based on the hydraulic pressure created by the oil pump, the hydraulic control system governs the hydraulic pressure acting on the torque converter clutch, clutches and brakes in accordance with the vehicle driving conditions.
There are three solenoid valves on the valve body.
The No. 1 and No.2 solenoid valves are turned on and off by signals from the ECM to operate the shift valves and change the gear shift position.
The No.3 solenoid valve is operated by signals from the ECM to engage or disengage the lock -up clutch of the torque converter clutch.
3. Electronic Control System
The electronic control system for the A241E and A244E provide extremely precise control of the gear shift timing and lock -up timing response to driving conditions as sensed by various sensors located throughout the vehicle and in response to the engine's running condition.
As the same time, the ECM control reduces vehicle squat when the vehicle starts out and gear shift shock. The electronic control system is also equipped with a self diagnosis system which diagnoses malfunctions of electronically controlled components and warns the driver, and a fail -safe which makes it possible for the vehicle to continue functioning when a malfunction occurs.
Construction
The electronic control system can be broadly divided into three groups; the sensors, ECM and actuators.