Abstract: A relief valve for an oil pump can prevent a main gallery from being damaged by largely decreasing peak pressure of an oil pump by using bypass flow according to oil pressure of the main gallery in cold start of an engine, and can control the discharging pressure of the oil pump at the optimum level when the engine is warmed up, by defining a housing chamber communicating with the main gallery of the engine and a plunger chamber bypassing some of oil flowing to the main gallery to the oil pump or an oil pan in accordance with oil pressure in the housing chamber using a plunger chamber, and by changing a modulus of elasticity of a coil spring elastically supporting the plunger in accordance with the oil pressure produced in the main gallery, by using a substance that is expanded by temperature.

Abstract: A relief valve for an oil pump, may include a housing defining a relief space, a plunger slidably disposed in the relief space and dividing the relief space into a housing chamber and a plunger chamber, an elastic member elastically supporting the plunger and being compressed by oil pressure of the main gallery, wherein the oil pressure of the main gallery may be relatively lower than an oil pressure under a warm-up state of the engine, a locator disposed under the plunger and supporting the elastic member, a plug coupled to a lower portion of the housing under the relief space and supporting the locator such that a modulus of elasticity in the elastic member may be changed by a change in seat position of the elastic member, and a negative pressure supplier selectively generating negative vacuum pressure in the locator such that a height of the locator changes.

Abstract: A relief valve for an oil pump, may include a housing defining a relief space, a plunger slidably disposed in the relief space and dividing the relief space into a housing chamber and a plunger chamber, an elastic member elastically supporting the plunger and being compressed by oil pressure of the main gallery, wherein the oil pressure of the main gallery may be relatively lower than an oil pressure under a warm-up state of the engine, a locator disposed under the plunger and supporting the elastic member, a plug coupled to a lower portion of the housing under the relief space and supporting the locator such that a modulus of elasticity in the elastic member may be changed by a change in seat position of the elastic member, and a negative pressure supplier selectively generating negative vacuum pressure in the locator such that a height of the locator changes.

Abstract: A relief valve for an oil pump can prevent a main gallery from being damaged by largely decreasing peak pressure of an oil pump by using bypass flow according to oil pressure of the main gallery in cold start of an engine, and can control the discharging pressure of the oil pump at the optimum level when the engine is warmed up, by defining a housing chamber communicating with the main gallery of the engine and a plunger chamber bypassing some of oil flowing to the main gallery to the oil pump or an oil pan in accordance with oil pressure in the housing chamber using a plunger chamber, and by changing a modulus of elasticity of a coil spring elastically supporting the plunger in accordance with the oil pressure produced in the main gallery, by using a substance that is expanded by temperature.