Fuel pump

Abstract

An engaging hole-of an impeller, which receives a shaft, is formed by an impeller first planar surface, which is contactable with a shaft first planar surface, an impeller second planar surface, which is contactable with a shaft second planar surface, and an impeller first curves surface-and an impeller second curved surface, which connect between the shaft first planar surface-and the shaft second planar surface. A first groove and a second groove, which are communicated with the engaging hole, are formed in the impeller first curved surface and the impeller second curved surface, respectively. When the shaft first planar surface contacts the impeller first planar surface upon rotation of the shaft in one direction, the first groove is deformed by an applied force. Thereby, the shaft second planar surface and the impeller second planar surface contact with each other.

1 . A fuel pump comprising:
 a pump case that includes a suction port, through which fuel is drawn into the pump case, and a discharge port, through which the fuel is discharged from the pump case;   a stator, around which a plurality of windings is wound, wherein the stator is configured into a tubular form and is received in the pump case;   a rotor that is rotatably placed on a radially inner side of the stator;   a shaft that is coaxial with the rotor and rotates integrally with the rotor; and   an impeller that includes an engaging hole, which receives one end portion of the shaft, wherein:   when the impeller is rotated integrally with the shaft, the impeller pressurizes the fuel drawn through the suction port and discharges the pressurized fuel through the discharge port;   the one end portion of the shaft includes a shaft side first contact surface, which is contactable with the impeller, and a shaft side second contact surface, which is parallel to the shaft side first contact surface and is contactable with the impeller;   the engaging hole includes an impeller side contact surface, which opposes one of the shaft side first contact surface and the shaft side second contact surface and is contactable with the one of the shaft side first contact surface and the shaft side second contact surface; and   the impeller includes at least one deformation enabling space that is deformed when the one of the shaft side first contact surface and the shaft side second contact surface contact the impeller side contact surface.   
     
     
         2 . The fuel pump according to  claim 1 , wherein:
 the impeller side contact surface is an impeller side first contact surface, which opposes the shaft side first contact surface and is contactable with the shaft side first contact surface;   the engaging hole further includes an impeller side second contact surface, which opposes the shaft side second contact surface and is contactable with the shaft side second contact surface;   the at least one deformation enabling space is deformed when the shaft side first contact surface and the impeller side first contact surface contact with each other, or when the shaft side second contact surface and the impeller side second contact surface contact with each other.   
     
     
         3 . The fuel pump according to  claim 2 , wherein the at least one deformation enabling space is at least one groove that is communicated with the engaging hole. 
     
     
         4 . The fuel pump according to  claim 3 , wherein:
 the engaging hole includes:
 an engaging hole first forming surface that connects between one side of the impeller side first contact surface and one side of the impeller side second contact surface; and 
   an engaging hole second forming surface that connects between another side of the impeller side first contact surface and another side of the impeller side second contact surface; and   the at least one groove includes a first groove, which is formed in the engaging hole first forming surface, and a second groove, which is formed in the engaging hole second forming surface.   
     
     
         5 . The fuel pump according to  claim 4 , wherein the first groove and the second groove extend in opposite directions, respectively, which are opposite to each other, when the first groove and the second groove are viewed from a central axis of the impeller. 
     
     
         6 . The fuel pump according to  claim 5 , wherein a radial length of the first groove and a radial length of the second groove are equal to each other. 
     
     
         7 . The fuel pump according to  claim 5 , wherein:
 the first groove is formed in a center of the engaging hole first forming surface; and   the second groove is formed in a center of the engaging hole second forming surface.   
     
     
         8 . The fuel pump according to  claim 1 , wherein the at least one deformation enabling space is at least one through-hole, which is formed on a radially outer side of the engaging hole and extends through the impeller in an axial direction of a central axis of the impeller. 
     
     
         9 . The fuel pump according to  claim 8 , wherein:
 the impeller side contact surface is an impeller side first contact surface, which opposes the shaft side first contact surface and is contactable with the shaft side first contact surface;   the engaging hole further includes an impeller side second contact surface, which opposes the shaft side second contact surface and is contactable with the shaft side second contact surface;   the at least one through-hole includes a plurality of through-holes, and a total number of the plurality of through-holes is an even number;   the plurality of through-holes is deformed when the shaft side first contact surface and the impeller side first contact surface contact with each other, or when the shaft side second contact surface and the impeller side second contact surface contact with each other; and   each of the plurality of through-holes is formed at a location which is point symmetric to another one of the plurality of through-holes about a symmetric point that is a point along the central axis of the impeller.   
     
     
         10 . (canceled) 
     
     
         11 . The fuel pump according to  claim 8 , wherein the plurality of through-holes is arranged one after another at equal intervals along an imaginary circle, which is centered at the central axis of the impeller. 
     
     
         12 . The fuel pump according to  claim 1 , wherein:
 the impeller includes:
 a plurality of tilt surfaces, which are arranged at a radially outer end part of the impeller, wherein the plurality of tilt surfaces pressurize and discharge the fuel through use of rotation of the impeller; and 
   an engaging hole forming surface that is formed to have a cross section configured into a shape of an arc, which is centered at a central axis of the engaging hole, wherein the engaging hole forming surface is connected to an end of the impeller side contact surface; and   the at least one deformation enabling space is placed on a radially inner side of an intermediate imaginary circle that is placed at a location that is radially equally spaced from both of:   an imaginary circle that is centered at the central axis of the engaging hole and circumferentially connects radially inner side parts of the plurality of tilt surfaces; and   an imaginary circle that is centered at the central axis of the engaging hole and circumferentially connects a radially outer side part of the at least one engaging hole forming surface.