Technical Aspects: Oil Pump & Types

Oil pump supplies oil under pressure to all moving parts of the engine in order to provide lubrication. Oil also plays an important role in dissipating the heat away from the internal components of the engine & also carries away the by-products of the combustion process and cleans the engine as it flows through the engine.

Technical Facts:

Oil pumps are usually driven by a chain or gears powered by camshaft/crankshaft. There are various types of oil pumps based on the design and components involved. Two most common oil pumps on the basis of application are:

1. Geared Oil Pump:

It consists of two toothed spur gears enclosed in a housing with very little clearance between gear teeth and housing. Only one of these gears is powered by camshaft/crankshaft and other gear is driven by this powered gear. These two gears rotate in such a way that oil is carried out between the gear teeth and pump housing, before being forced down the outlet. This imparts pressure to oil, however the amount of pressure created depends upon gears rotational speed and temperature of oil.

Oil is prevented from getting highly pressurized with the help of pressure relief valve placed across the inlet and outlet connections. This valve opens in case of high pressure conditions and some amount of oil is redirected from outlet to inlet.

2. Rotor-Type Oil Pump:

Many engines are equipped with rotor type oil pump. It has a central rotor with outer lobes which continuously rotates inside the outer ring having internal lobes. This rotor is fixed on driving spindle (crankshaft/camshaft according to the position in which it is mounted). As the rotor spins, it also causes outer ring to spin along with it.

• Rotor and outer ring are placed eccentrically so that each of its lobes makes contact with inner surface of outer rotor. The mechanism to pressurize the oil is same as gear-type oil pump.
• The oil sucked from inlet (due to lower pressure) is carried out between the lobes and continuous cycle of changing pocket size in between lobes imparts pressure to oil which is finally forced down the outlet.

Watch how oil pump works:  

Also Read: Technical Aspects: Crankcase Ventilation