Engine oil system with oil pressure regulator to increase cam phaser oil pressure

Abstract

A lubrication system for an internal combustion engine having a pressure regulator to optimize oil flow through an engine to increase engine efficiency. The lubrication system includes an engine driven oil pump connected to supply pressurized oil through a main oil feed to a main bearing gallery, a cam gallery and a hydraulically actuated device such as a cam phaser or switching valve lifters. A pressure regulator connected between the main oil feed and the galleries selectively restricts oil flow to the galleries to raise oil pressure supplied to the hydraulically actuated device. The increased oil pressure to the cam phaser allows the engine to use a smaller oil pump and thereby increase engine efficiency while providing for actuation of the cam phaser over the full engine speed range. The increased oil pressure to the switching lifters allows the engine to reduce valve lift or disable cylinders over the full engine speed range.

Description

TECHNICAL FIELD [0001] This invention relates to engine oil systems and, more particularly, to a system including a pressure regulator to optimize oil flow and pressure for various lubrication and actuation functions. BACKGROUND OF THE INVENTION [0002] Internal combustion engines may use lubricating oil for many purposes including, for example, lubricating moving parts, actuating cam phasers, and controlling valve lifters for cylinder deactivation. Cam phasers and cylinder deactivation devices generally require a higher oil pressure for actuation during engine operation than the moving parts of the engine require for proper lubrication. [0003] One approach to maximize engine efficiency is to use a smaller oil pump to provide only the minimum amount of oil pressure needed to prevent engine wear. However, smaller oil pumps do not provide enough oil pressure to actuate a cam phaser at low and idle engine speeds. Thus the cam phaser can be operated only at higher engine speeds. [0004] A...

AI Technical Summary

Benefits of technology

[0007] The present invention provides an oil system for an internal combustion engine having a pressure regulator to optimize oil pressures in the engine while increasing engine efficiency by minimizing parasitic losses created from over lubrication.

[0010] The restriction of oil flow to the main gallery created by the regulator forms back pressure which increases oil pressure in the main feed. The increased oil pressure within the main feed is then directed to the hydraulically actuated device. As a result, the amount of oil pressure to the hydraulically actuated device is increased while the rest of the oil system operates at a lower oil pressure. This allows cam phasing or cylinder deactivation at engine idle or other conditions when oil pump pressure is normally too low to actuate the cam phaser or the switching lifters. The additional oil pressure supplied to the hydraulically actuated device allows the phaser to vary valve timing at all engine speeds without a large increase in the size of the oil pump. The use of a smaller oil pump reduces parasitic losses for increased engine efficiency.

Problems solved by technology

However, smaller oil pumps do not provide enough oil pressure to actuate a cam phaser at low and idle engine speeds.

However, the efficiency gains are not without cost.

A higher pressure produced by larger oil pump supplies excess flow that over lubricates the moving parts of the engine and requires additional energy to drive the pump, creating parasitic losses that reduce engine efficiency.

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