What types of oil pumps are commonly used in automatic transmissions?
2 Answers
In the oil supply system of automatic transmissions, there are two types of oil pumps: fixed displacement pumps and variable displacement pumps: 1. Commonly used fixed displacement pumps include: (1) Internal gear pumps: Internal gear pumps are the most widely used type of oil pump in automatic transmissions. They feature compact structure, small size, light weight, strong self-priming capability, and minimal flow fluctuation. (2) Rotor pumps: These are a type of internal gear pump with special tooth profiles, characterized by simple structure, compact size, smooth operation, and excellent high-speed performance. (3) Vane pumps: Composed of a stator, rotor, vanes, housing, and pump cover, they have a complex structure and are sensitive to hydraulic oil contamination. 2. Variable displacement pumps are designed by modifying the vane pump in automotive automatic transmissions to have variable displacement. The oil delivery volume of a variable displacement pump stops increasing once the engine speed exceeds a certain threshold, thereby reducing the operational resistance of the pump at high speeds and improving the vehicle's fuel economy.
During automatic transmission maintenance, I found that the oil pump is the core component of the entire system. The commonly used type is the gear pump, especially the internal gear pump, because of its simple and reliable structure, low cost yet high efficiency. When the engine is running, the oil pump starts working, drawing transmission fluid from the oil pan to create oil pressure for operating clutch assemblies and lubricating internal components. If the oil pump develops issues, such as wear or blockage, it can lead to insufficient oil pressure, delayed or jerky gear shifts, and even cause transmission overheating and damage. Regularly checking the fluid condition and replacing the oil filter are key steps to prolong the pump's lifespan. I recommend car owners to conduct a comprehensive inspection every few years to prevent minor faults from accumulating into major problems. Most new cars still use this type of pump today, proving its practicality.
