Relief device for oil pump

摘要

A relief device for an oil pump that can ensure an appropriate pressure of oil discharged from the oil pump in a high-revolution region of an engine, ensure satisfactory lubrication ability in a medium-revolution region, and improve the efficiency of the engine. The relief device includes a relief housing A constituted by a relief inflow portion 2, a valve passage portion 3, a recess 4, and an oil discharge portion 5 having a relief hole 51; a relief valve 6 having a small-diameter portion 63 between a first large-diameter portion 61 and a second large-diameter portion 62; and a spring 7 elastically biasing the relief valve 6 toward the relief inflow portion 2. The recess 4 is formed at a position that is closer to the relief inflow portion 2 side than to the oil discharge portion 5, the axial length of the recess 4 is larger than the axial length of the first large-diameter portion 61 of the relief valve 6, and the shortest axial distance between the recess and the relief hole is less than the axial length of the small-diameter portion 63.