Operating principle of an automatic transmission
An automatic transmission (AT) is a type of transmission that automatically changes gears without driver intervention. It consists of the following main components:
* Torque converter (GTR)
* Planetary gearbox
* Brake bands and clutches
* Automatic transmission control module
Torque converter (GTR)
GTR is a device that transmits torque from the engine to the gearbox. It consists of three main elements:
* Turbine
* Pump
* Stator
The turbine is connected to the engine shaft, and the pump is connected to the gearbox shaft. The stator is located between them and does not rotate.
When the engine is running, the turbine receives torque from the pump through the stator. The stator directs the flow of fluid, creating additional torque. This allows the automatic transmission to move away without jerking and ensures smooth gear shifting.
Planetary gearbox
A planetary gearbox is a device that transmits torque from one speed to another. It consists of the following elements:
* Sun gear
* Planetary gears
* Ring gear
The sun gear is located in the center of the gearbox and is connected to the motor shaft. The planetary gears rotate around the sun gear ????????????????????????????????????????????? ????????????????????????????????? Crown gear is located outside the gearbox and is connected to the gearbox shaft.
Gear shifting is accomplished by turning on or off the brake bands and clutches, which lock or unlock certain elements of the planetary gearbox.
Brake bands and clutches
Brake bands and clutches are devices that are used to engage and disengage gears. Brake bands stop the rotation of certain elements, and clutches transmit torque from one element to another.
Automatic transmission control module
The automatic transmission control module is an electronic control unit that controls the operation of the automatic transmission. It receives signals from various sensors such as the speed sensor, throttle position sensor and gas pressure sensor.
Based on these signals, the control module determines when and which gears need to be changed. It also controls the operation of the turbocharger, brake bands and clutches.
How does automatic transmission work?
When the driver moves the automatic transmission selector to position “D” (Drive), the automatic transmission control module engages the clutch connecting the engine to the GTR. The GTR transmits torque to the planetary gearbox, where the brake bands and clutches are engaged to engage first gear.
As vehicle speed increases, the control module changes gears, engaging and disengaging various elements of the planetary gearbox through the brake bands and clutches. The GTR is also locked at higher speeds to improve efficiency.
When the driver presses the brake pedal, the control module reduces the pressure in the brake pedal and engages the brake bands, slowing the vehicle. When you come to a complete stop, the parking clutch engages, which locks the gearbox.