Fuel pump

Abstract

A fuel pump includes a pump cover on one side of a housing, a cover end portion on the other side of the housing, a stator inside the housing, a rotor inside the stator, a shaft rotatable with the rotor, an impeller rotatable with the shaft to pressurize fuel inside the housing, a bearing portion provided in the cover end portion on its center axis to slidably support an end part of the shaft, and a relief valve capable of reducing a fuel pressure inside the housing. The cover end portion has an end surface located on its side opposite from the pump cover, and the relief valve includes a valve seat located on an opposite side of the end surface of the cover end portion from the pump cover.

What is claimed is: 
     
         1 . A fuel pump comprising:
 a housing having a hollow cylindrical shape;   a pump cover closing an end opening of the housing on a first side of the housing in an axial direction of the housing, the pump cover including a suction portion;   a cover end portion having a circular plate shape to close the other end opening of the housing on a second side of the housing in the axial direction of the housing, the cover end portion including a press-fit part that is located on an outer rim of the cover end portion to be press-fitted to an inner side of the housing;   a stator having a hollow cylindrical shape, the stator being accommodated inside the housing and including a plurality of wound wires;   a rotor rotatably provided inside the stator;   a shaft provided coaxially with the rotor to rotate together with the rotor;   an impeller connected to one end of the shaft, wherein the impeller rotates together with the shaft to draw a fuel through the suction portion and pressurize the drawn fuel;   a bearing portion provided in the cover end portion on a center axis of the cover end portion to slidably support the other end of the shaft;   a discharge portion provided in the cover end portion to be used as a port through which the fuel pressurized by the impeller is discharged; and   a relief valve capable of reducing a fuel pressure in a space provided between the pump cover and the cover end portion in the housing when the fuel pressure in the space becomes higher than or equal to a predetermined value, wherein the relief valve includes:   a cylindrical portion integrated with the cover end portion to protrude outward from an end surface of the cover end portion on the second side of the housing;   a valve seat provided inside the cylindrical portion;   a valve member capable of contacting the valve seat; and   an urging member having an end part contacting the valve member to urge the valve member toward the valve seat,   the valve member is separated from the valve seat when the relief valve reduces the fuel pressure in the space, and   the valve seat is located outside the cover end portion on the second side of the housing.   
     
     
         2 . The fuel pump according to  claim 1 , wherein the relief valve is located a predetermined distance away from the center axis of the cover end portion. 
     
     
         3 . The fuel pump according to  claim 2 , wherein
 the relief valve further includes a stop member that is provided inside an end part of the cylindrical portion to fix another end part of the urging member on an opposite side of the urging member from the valve member, and   the end part of the cylindrical portion extends radially inward of the cylindrical portion to fix the stop member inside the cylindrical portion.   
     
     
         4 . The fuel pump according to  claim 3 , wherein the end part of the cylindrical portion is deformed by thermal melting, pressing and subsequent cooling to extend radially inward of the cylindrical portion.