Fuel supply pump

Abstract

A fuel supply pump, which is simple in construction and easy to produce and is capable of efficiently pressurizing a high flow rate of fuel, is provided. The fuel supply pump ( 50 ) includes a housing ( 52 ), a plunger barrel ( 53 ), a plunger ( 54 ) for pressurizing fuel, which is installed in the plunger barrel ( 53 ) so as to be allowed to move up and down, a cam ( 60 ) installed in rotation way below the plunger ( 54 ), a tappet structure body ( 6 ) installed between the cam ( 60 ) and the plunger ( 54 ) to transmitting the turning force, serving as a lifting force, from the cam shaft ( 3 ) to the plunger ( 54 ), a tappet structure body ( 6 ) installed between the cam ( 60 ) and the plunger ( 54 ) and provided for transmitting a upward or downward movement of the cam ( 60 ) caused by the rotation of the camshaft ( 3 ) to the plunger ( 54 ); and a return spring ( 68 ) for setting lowering force to the plunger ( 54 ), which is installed between the tappet structure body ( 6 ) and the plunger barrel ( 53 ).

1 . A fuel supply pump comprising: 
 a pump housing having a cylindrical space opened from end to end in the vertical direction;    a plunger barrel installed in the upper opening portion of the pump housing;    a plunger for pressurizing fuel, installed in the plunger barrel and the cylindrical space of the pump housing so as to be allowed to move up and down;    a cam installed in rotation way below the plunger and integrated with a cam shaft inserted into the pump housing;    a tappet structure body installed between the cam and the plunger and provided for transmitting a upward or downward movement of the cam caused by the rotation of the cam shaft to the plunger; and    a return spring for setting lowering force to the plunger, installed between the tappet structure body and the plunger barrel,    wherein the plunger barrel has a projection for supporting the upper end of the return spring.    
   
   
       2 . The fuel supply pump as described in  claim 1 , wherein 
 the plunger barrel has a large diameter portion for restricting the movement of the return spring in the radial direction.    
   
   
       3 . The fuel supply pump as described in  claim 1 , wherein 
 the projection of the plunger barrel has an outer peripheral surface fitted to the peripheral surface of the cylindrical space of the pump housing.    
   
   
       4 . The fuel supply pump as described in  claim 3 , wherein 
 the plunger barrel has a seal ring receiver in the outer peripheral surface of the projection.    
   
   
       5 . The fuel supply pump as described in  claim 1 , further comprising: 
 a spring sheet having an opening portion for penetrating the plunger there into is provided between the return spring and the tappet structure body: and    a spring holding portion for restricting the downward movement of the return spring is provided in the outer peripheral surface of the spring sheet.    
   
   
       6 . The fuel supply pump as described in  claim 1 , wherein 
 the tappet structure body further includes a cylindrical shell having an outer peripheral surface fitted to the peripheral surface of the cylindrical space of the pump housing and the inner peripheral surface of the shell is provided with an projection for restricting the movement of the return spring in the radial direction.    
   
   
       7 . The fuel supply pump as described in  claim 1 , wherein 
 the fuel supply pump is used in an accumulator fuel injection device for pressurizing fuel at a flow rate of 500 to 1,500 litters per hour to a value of 50 MPa or more.