Automatic transmission device with torque converter
Torque converter
The torque converter transfers power from the engine to the transmission. It consists of:
* Pump wheel (pump): Driven by the engine flywheel and pumps transmission fluid.
* Reactor Wheel: Located between the pump and turbine, directing the fluid back to the pump.
* Turbine wheel: Connected to the gearbox input shaft.
Hydraulic block
The hydraulic unit controls gear shifting in response to inputs from the vehicle’s computer and throttle position. It consists of:
* Valve Body: Contains a series of valves that direct fluid to various hydraulic circuits.
* Control Solenoid Block: Electronically controlled valves that control fluid flow through the hydraulic block.
* Hydraulic Pistons: Operate friction and band brakes that operate various gears.
Mechanical block
The mechanical unit contains the actual gears that provide the different gear ratios. It consists of:
* Gears: Sets of gears of different sizes that provide different gear ratios.
* Friction Discs: Heat resistant discs that touch to engage and disengage gears.
* Band Brakes: Used to prevent more than one gear from being engaged at the same time.
Electronic control unit
The electronic control unit (ECU) controls the operation of the automatic transmission by receiving input data from various sensors and controlling the solenoids of the hydraulic unit. It determines gear shift timing based on:
* Vehicle speed
* Throttle Positions
*Transmission fluid temperature
* External conditions (such as road slope)
Operating principle
1. The rotation of the engine causes the torque converter pump wheel to pump fluid, which rotates the turbine wheel.
2. The hydraulic unit directs fluid to the appropriate hydraulic circuits to operate the friction discs or band brakes.
3. Engaged friction discs or band brakes lock the gears at the desired gear ratio.
4. The turbine wheel transmits power to the gears to propel the vehicle.
5. The torque converter allows the engine to operate at a lower speed than the transmission, providing smooth starting and shifting.
6. The ECU continuously monitors operating conditions and adjusts the transmission to optimize performance and fuel efficiency.