The design and principle of operation of the automatic transmission in Nissan cars:
Nissan automatic transmission device:
*Hydraulic Transformer: Connects the engine and transmission, transmitting power through rotating fluid. It provides a smooth start and an additional gear ratio.
* Planetary Gearbox: A mechanism consisting of a set of gears that provides various gear ratios.
* Friction and steel discs: These discs interact to engage and disengage the gears within the planetary gearbox.
* Pump: Creates hydraulic pressure to power the friction discs and control fluid flow in the transmission.
*Hydraulic control unit: Controls fluid flow and pressure to shift gears and lock up the torque converter.
* Electronic Control Unit (ECU): Controls the hydraulic unit, monitoring pressure, temperature and other parameters of the gearbox.
Principle of operation of Nissan automatic transmission:
1. Pulling off:
*Hydraulic transformer provides high gear ratio, increasing engine torque.
* Clutches and steel discs engage first gear.
2. Gear shift up:
* The ECU determines when a gear shift is necessary.
* The hydraulic control unit increases the hydraulic fluid pressure by switching a set of friction discs and disabling the previous one.
* The planetary gearbox changes the gear ratio, reducing engine speed at higher speeds.
3. Torque converter lock:
* At high speeds, the torque converter locks, connecting the engine and transmission directly.
* This reduces power loss and improves fuel efficiency.
4. Gear shift down:
* The ECU determines when it is necessary to downshift (for example, when accelerating or descending a mountain).
* The hydraulic control unit reduces the hydraulic fluid pressure by shifting the friction disc set and engaging a lower gear.
5. Reverse:
* Reverse gear is activated by a separate set of friction discs.
* Planetary gearbox changes the direction of movement.
Advantages of Nissan automatic transmission:
* Smooth gear shifting
* Ease of driving
* Reduced engine and transmission wear
* Increased fuel efficiency (depending on transmission type)