We've all heard it, right? "Most engine wear occurs when starting the engine".
I've read of engines running for something like 50 years without a stop for an electrical plant or something like that. Then someone tears it down and finds that the bearings look like new.
The theory behind it all appears to be that after an engine stops, the oil, by gravity, drains out of all the bearings. The bearings rub more or less directly (though there will probably be a minuscule oil film still on it) Then, when someone starts the engine, there is a split second where nothing is lubricated. This is a bigger problem with OHC engines than other types, as the cam is the farthest component from the oil pump. At least it is on all the engines I know.
Some manufacturers try to help the problem by using thinner oil, and then just making bearing clearance smaller. This works well, but the engine still isn't lubricated when you first start the engine.
So... I was pondering the problem and thinking about how wonderful it would be to have an engine that was lubricated
before the engine started. So I came up with an idea. It is actually quite simple.
First, lets assume your oil pump normally gives about 65psi. Of course, the pressure varies somewhat depending on engine speed. Assume that the pressure release valve starts dumping oil back to the crankcase at 60psi. Now, you tap into the oil channels after the pump, but before the pressure release valve. You connect a hidroaccumulator much like a water tank (capacity of about 250ml.) in there, then hook a one way electric valve in front of the hidroaccumulator. When the valve is closed, fluid can enter the hidroaccumulator, but not flow out. When the valve is opened, fluid can flow in either direction.
Using this arrangement, if the hidroaccumulator is full when then engine is stopped, you can hook everything up electrically such that until the engine stops, the valve is closed. When the engine is not running, the valve should be closed. Then, when the key is turned on, the valve opens and sends oil throughout the engine before the oil pump even starts working. Once the pump starts working, your accumulator pressure has fallen, so if it is as, say, 45psi, the pump pumps it back up to 60 and the engine and accumulator fill. Ideally, there should a biased valve in there to make sure the engine gets oil before the accumulator. Using that type of hydraulic circuit, the accumulator is filled with the extra pressure and volume that would have been spit out the pressure release valve.
A manual switch, or a switch that only goes off with the glow plugs would be required with diesel engines, as the accumulator would probably be dry before the engine is turned after waiting for the glow plugs.
Also, this would be particularly beneficial on engines that have holes in the connecting rods for oiling the cylinder wall.
Another side benefit is that theoretically, one should be able to use thinner oil because there is no minuscule oil film needed on the bearing surfaces.
BTW, I'm not responsibly if you try this and blow your engine. So far, this is only a theoretical solution for the increased engine wear caused by repeated engine starts and stops.
Feel free to critique my idea, its advantages and problems and whatever else I may have said wrong or right
