The principle of gear shifting in an automatic transmission (automatic transmission)
An automatic transmission uses a hydraulic mechanism to shift gears, which is controlled by the transmission control module (TCM).
Main components of the gear shift mechanism:
* Torque Converter: Converts torque from the engine into hydrodynamic energy.
* Planetary gears: mechanical devices that transmit power and change gear ratios.
* Clutch packs: Multi-plate clutches that connect or disconnect planetary gears.
* Switch drum: controls the on and off of the friction packs.
* Shift Valves: Solenoid valves that direct hydraulic fluid to the corresponding clutch packs.
Speed shift diagram:
1. When the driver selects a gear: The TCM sends a command to the shift valve corresponding to the desired gear.
2. The shift valve opens: Hydraulic fluid flows to the corresponding clutch pack.
3. Friction packs are compressed: Fluid pressure creates a frictional force that connects the planetary gears needed for the desired transmission.
4. Switch drum rotates: The drum rotates to set the friction packs to the on or off position.
5. Hydraulic Pressure Regulated: The TCM controls fluid pressure to ensure smooth shifting and prevent transmission slipping or overload.
6. Disengaging the previous gear: The shift valve corresponding to the previous gear closes, releasing fluid pressure in the corresponding clutch pack. The friction packs are separated, disabling the previous gear.
Advantages of automatic transmission:
* Convenience and ease of use
* Smooth gear shifting
* Optimized performance and fuel economy
*Transmission overvoltage protection