What are the applications of powder metallurgy in oil pumps?

What are the applications of powder metallurgy in oil pumps?

At present, the engine oil pump and the automatic transmission oil pump mostly use the constant displacement oil pump. The constant displacement oil pump is generally made of powder metallurgy, including external gear pump, internal gear cycloidal pump or internal gear pump.

powder metallurgy

The oil output of fixed displacement oil pump increases with the increase of engine speed, and the relationship between them is linear. In order to ensure the minimum oil output at low speed and the minimum oil pressure at high speed, the oil pump will be designed to be larger, which puts forward higher requirements for the layout of the engine compartment. At the same time, when the engine is at a high speed, the excess lubricating oil will return from the oil circuit, resulting in increased engine power consumption. The variable displacement oil pump will adjust the oil pressure and oil volume according to the working conditions of the engine, so as to achieve the purpose of oil saving.

The research data show that in the engine with constant displacement oil pump, when the speed is more than 2500r/min, about 50% of the active oil directly flows back to the oil inlet chamber or oil pan of the oil pump through the pressure relief valve, resulting in a waste of energy; The use of variable displacement oil pump instead of fixed displacement oil pump can generally save fuel by 2%~5% and reduce CO2 emissions by 1%~2%.

Variable displacement pump generally has the structure of external gear pump, vane pump and sliding vane pump. For externally engaged gear pumps, such as Volkswagen's EA888 project, the axial position of one gear is fixed, and the axial position of the other gear is adjusted with the pressure by a spring. When idling, the two gears are fully engaged. When the speed increases, the pressure of the oil pump increases, and the gear engagement part becomes shorter after the spring is compressed, so that the flow of the oil pump can be adjusted at any time. The gears of this type of pump are made by powder metallurgy technology.

Vane variable displacement pump is mainly composed of stator, rotor and blade, of which the stator and rotor are powder metallurgy parts. The working principle of the vane variable displacement pump is to adjust the eccentricity through pressure, thereby adjusting the flow. The principle of sliding vane variable displacement pump is basically the same as that of vane variable displacement pump, and the flow is adjusted by adjusting the eccentricity. The sliding vane is a steel piece, the intermediate sleeve is connected with the sliding vane, the sliding sleeve is outside, and the rotor is in the middle. These three pieces are all powder metallurgy pieces.