Patent ID: 9453440
Filing Date: 2016-09-27
CPC Classification: F01M,G05D,Y10T

Claim Text:
1. An oil pump for an internal combustion engine, comprising: a relief valve including a back pressure chamber, and configured to adjust a pump discharge pressure depending on a differential pressure between the pump discharge pressure and a back pressure chamber pressure, wherein the pump discharge pressure is a discharge pressure of the oil pump, and wherein the back pressure chamber pressure is an oil pressure in the back pressure chamber; an electromagnetic switching valve including: a pilot valve disposed downstream of the electromagnetic switching valve, and configured to operate upon receipt of at least one of the pump discharge pressure and the back pressure chamber pressure, and control an oil pressure supplied to the back pressure chamber of the relief valve, wherein: the electromagnetic switching valve is configured to control the back pressure chamber pressure by selectively allowing and preventing fluid communication between a discharge passage and a back pressure passage by operating the ball valve element depending on an operating state of the internal combustion engine; the pump discharge pressure is applied to the discharge passage; and the back pressure passage includes an end open to the back pressure chamber of the relief valve, and wherein the pilot valve includes: a supply port configured to receive supply of the pump discharge pressure from the discharge passage directly or through the back pressure passage; a discharge port configured to discharge the supplied pump discharge pressure; a cylinder, wherein the supply port includes an end open to the cylinder, and wherein the discharge port includes an end open to the cylinder; a pilot valve element slidably mounted in the cylinder, and including an end portion including a pressure-receiving surface configured to receive the supplied pump discharge pressure, and configured to vary an opening area of the discharge port by sliding in accordance with the supplied pump discharge pressure; and a biasing member configured to bias the pilot valve element in a direction to close the discharge port.