How Does the Car Oil Pump Work?

The role of the oil pump in the engine system.

The oil pump is the power source of the oil circulation in the engine lubrication system. The oil pump is installed in the lower part of the engine block. When it rotates, the oil in the oil pan is pressurized and discharged to the lubricating oil circuit and then enters the mist lubricating parts after being filtered by the oil filter. If the performance of the oil pump decreases, the oil pressure decreases, which will seriously affect the normal operation of the engine.

1, Affect the normal operation of parts that need to be lubricated and accelerate wear, such as turbochargers and other important parts;

2, For the engine that widely uses hydraulic tappets, it will cause valve noise;

3, The engine variable valve timing technology relies on the oil pressure as the control power source. If the oil pressure is abnormal, it will affect the work of the variable valve timing;

What are the types of oil pumps?

Rotor pump and vane pump as far as the oil pump of the automobile lubrication system is concerned, are the commonly used external gear pump, internal gear pump and rotor pump.

External gear oil pump:

The external gear pump consists of two identical gears and pumps casings; two chambers are formed: an oil suction chamber and an oil pressure chamber;

The driving gear is driven to rotate by the camshaft or the crankshaft. In the oil suction chamber, the driving gear and the driven gear are gradually disengaged, and the oil suction chamber volume increases. The oil is sucked into the oil suction chamber and brought in by the backlash between the gear and the pump casing. In the oil pressure chamber, the driving and driven gears gradually mesh, the volume of the oil pressure chamber is reduced, and the oil is discharged to the lubricating oil passage.

The actual oil supply of the oil pump is 2-3 times larger than the oil circulating in the lubrication system, and the excess oil flows back to the oil pan through the pressure limiting valve.

Therefore, the pump oil pressure of the oil pump depends on the speed of the engine, the gap between the gear and the pump casing, and the setting of the pressure limiter. In large, the pump oil pressure of the oil pump is reduced. Replace the oil pump during the actual overhaul.

In fact, all oil pump structures are divided into an oil suction chamber and an oil pressure chamber. When the volume of the oil suction chamber increases, the oil is sucked in, while the volume of the oil pressure chamber decreases, and the oil is hung out.

Internal gear oil pump

Rotary Oil Pump:

The rotor-type oil pump consists of a casing, an inner rotor, an outer rotor, and a pump cover. The inner rotor is keyed or pinned to the rotor shaft and driven directly or indirectly by the crankshaft gear.

The center of the inner rotor and the outer rotor are not concentric and there is an eccentricity, and the inner rotor drives the outer rotor to rotate together in the same direction. The inner rotor has 4 convex teeth, and the outer rotor has 5 concave teeth so that the inner and outer rotors rotate in the same direction and asynchronously.

The tooth profile of the rotor is designed so that when the rotor rotates to any angle, the tooth profile of each tooth of the inner and outer rotors can always be in point contact with each other. In this way, 4 working chambers are formed between the inner and outer rotors. With the rotation of the rotor, the volumes of these 4 working chambers are constantly changing. In the cavity on one side of the oil inlet, due to the disengagement of the rotor, the volume gradually increases, a vacuum is generated, the oil is sucked in, the rotor continues to rotate, and the oil is brought to the side of the oil outlet. At this time, the rotor just enters the meshing, so that the volume of this cavity is reduced, the oil pressure is increased, and the oil is squeezed out from the teeth and sent out through the oil outlet so that with the continuous rotation of the rotation, the oil is continuously inhaled and pressed out.

The rotary oil pump has a compact structure, small size, lightweight, large oil suction vacuum, large pump oil volume, good oil supply uniformity, low cost, and is widely used in medium and small engines.