Oil Pump Blues

I think a smart explanation is in order! :smiley:

Forgot the link: http://randomarticleproject.blogspot.com/2010/06/oil-pump-internal-combustion-engine.html

What are you looking for? An automotive oil pump in any configuration is what’s termed a positive displacement pump. It simply means that it moves a given volume of fluid for each rotation. This is opposed to most other forms of pumps which merely provide a pressure differential where the flow is what the flow is. There’s always some minor leakage, but positive displacement pumps are irresistible.

Most of us view flow as from an electrical wall outlet or sink spigot. There you have a given applied pressure (120VAC or your pump/street pressure for water) that flows through a given restrictions (the length of the wire or pipes) and a resultant flow rate.

Positive displacement pumps dictate the circuit somewhat differently. There the flow rate is the determining factor. So you have a given flow rate through a given restriction that results in a given pressure result.

5gpm through a 1/2" pipe
5gpm through a 2" pipe

Q: which one flows more?
A: Both flow 5gpm The 1/2" pipe produces higher velocity and pressure for the same 5gpm

Now since the connection is somewhat “solid liquid”, the pumps are fitted with relief valves to limit the peak pressure that can be attained. This can be done to limit the stress produced when fluids are heavier/thicker. Once in relief, the circuit resorts to the more conventional view of pressure/resistance= flow rate.

I hope I didn’t just waste my time there with you looking for something else. :smiley:

Here’s a great site showing good animations of pumps



A smart explanation of what? Bernoulli’s laws of fluid dynamics?

Geeses posted a nice diagram of the dynamics of various positive displacement pumps, of which oil pumps are. But understand that it’s a wee bit more complicated. The pump basically just draws oil up from the pool om the oilpan and pressurizes the lubrication circuits. Oil lubricates components like sleeve bearings (main bearings and rod bearings) by creating a pressurized oil barrier between the parts. And…

Naw, nevermind. There exists no way to do this without using jargon. But understand that fluids not only conform to their cavities but they also exert pressure on the cavity surfaces. It’s that pressure that’s the real key to lubricating the engine…

Naw, nevermind. I cannot do this.

Click on anything you want and write anything you want, just don’t waste other peoples time with it.