1. Field of the Invention
The present invention relates generally to a pressure control valve and, more particularly, to a method for controlling the pilot pressure delivered to a pressure control valve of an engine oil pump.
2. Discussion
Engine lubrication is necessary to reduce friction and thus prevent excessive engine wear. To reduce friction, an oil pump circulates oil or other lubricants (under pressure) through the engine block, cylinder heads, etc. of a motor vehicle to lubricate its various moving parts, such as the camshaft, crankshaft, pistons and other various bearings.
Various ways have been proposed for controlling the amount of oil supplied to the engine. One way in which the amount of oil can be controlled is through a pressure control valve which selectively supplies oil from the pump to the engine. Typically, the oil pressure prevailing at the outlet of the oil pump is used to actuate the pressure control valve. Actuation of this control valve causes oil to be re-circulated back to an internal chamber of the oil pump or the oil sump. In this way, the pressure control valve not only controls the flow of oil into the lubrication circuit, but also regulates the output oil pressure from the pump.
It is an object of the present invention to control the flow of lubrication from the oil pump by using a pressure control valve, and thereby regulate pressure in the lubrication system.
It is another object of the present invention to blend or combine the oil pressure prevailing at the outlet of the oil pump with the oil pressure prevailing at or near the end of the remaining lubrication circuit for providing a more stable means of controlling the pressure control valve.
It is yet another object of the present invention to prevent excessive pump pressure during a cold start by blending or combining the oil pressure prevailing at the outlet of the oil pump with the oil pressure prevailing at or near the end of the remaining lubrication circuit, thereby providing a more stable means of controlling the pressure control valve, and during warm operation, the pressure control valve is actuated using the oil pressure prevailing at or near the end of the lubrication circuit, thereby better regulating oil pressure for all bearings regardless of the bearing clearance condition.