Pump for Supplying High-Pressure Fuel

Abstract

A small-sized and simple sliding portion structure for suppressing the deformation of a sliding portion caused by discharge pressure and the external force in fixing, and a pump for supplying high-pressure fuel having the sliding portion structure mounted thereon is provided. A plunger type pump for supplying high-pressure fuel including a cylinder which forms a sliding portion, a plunger which is slidably provided in the cylinder and reciprocates with the rotation of a cam, and a holder member which urges the cylinder against a body, has a configuration in which the cylinder is provided with a holding unit separately from the sliding portion, the holding unit is urged in the direction of the body with an urging force in the axial direction of the sliding portion to form a high-pressure sealing portion, and the cylinder has the sliding portion with the plunger on the low-pressure side than the high-pressure sealing portion.

1 .- 11 . (canceled) 
     
     
         12 . A pump for supplying high-pressure fuel comprising a plunger which pressurizes fuel in a pressurizing chamber, a cylinder which guides the reciprocating movement of the plunger on an inner peripheral side face of the same, and a body in which the cylinder is arranged, and wherein the cylinder has an opposing face which opposes the body, and wherein the entire cylinder is disposed on the side opposite to the pressurizing chamber relative to the opposing face. 
     
     
         13 . A pump for supplying high-pressure fuel comprising a plunger which pressurizes fuel in a pressurizing chamber, a cylinder which guides the reciprocating movement of the plunger on an inner peripheral side face of the same, and a body in which the cylinder is arranged, and wherein the cylinder has a large-diameter portion and a small-diameter portion, and wherein the large-diameter portion is disposed closer to the pressurizing chamber side than the small-diameter portion. 
     
     
         14 . The pump for supplying high-pressure fuel according to  claim 13 , wherein the large-diameter portion and the small-diameter portion are disposed on the opposite side of the pressurizing chamber relative to the body. 
     
     
         15 . The pump for supplying high-pressure fuel according to  claim 12 , wherein a sealing portion is formed by pressing the end of the cylinder on the pressurizing chamber side against the body. 
     
     
         16 . The pump for supplying high-pressure fuel according to  claim 12 , wherein a large-diameter portion and a small-diameter portion are provided in the cylinder, wherein the large-diameter portion is disposed closer to the pressurizing chamber side than the small-diameter portion, and wherein the large-diameter portion comes into contact with the body. 
     
     
         17 . The pump for supplying high-pressure fuel according to  claim 12 , wherein a large-diameter portion and a small-diameter portion are provided in the plunger, wherein a low-pressure fuel portion whose volume increases or decreases with the reciprocating movement of the plunger is formed, and
 wherein the low-pressure fuel portion is located outside the inner peripheral side face in the radial direction.   
     
     
         18 . The pump for supplying high-pressure fuel according to  claim 13 , wherein a connection portion between the large-diameter portion and the small-diameter portion forms a stepped portion in a stepped form, and receives the urging force in the axial direction by the stepped portion. 
     
     
         19 . The pump for supplying high-pressure fuel according to  claim 13 , wherein the connection portion between the large-diameter portion and the small-diameter portion forms a tapered portion in a tapered form, and receives the urging force in the axial direction in the tapered portion. 
     
     
         20 . The pump for supplying high-pressure fuel according to  claim 17 , wherein a wall surface forming the low-pressure fuel portion includes both of part of the cylinder and part of the plunger. 
     
     
         21 . The pump for supplying high-pressure fuel according to  claim 12 , wherein a pressurizing chamber whose volume increases and decreases with the reciprocating movement of the plunger is formed in the body, and
 wherein the pressurizing chamber is formed in a cylindrical shape having an inner diameter which is approximately equal to the outer diameter of the plunger.   
     
     
         22 . The pump for supplying high-pressure fuel according to  claim 21 , wherein a suction passage which sucks fuel into the pressurizing chamber and a discharge passage which discharges fuel from the pressurizing chamber are formed, and
 wherein the position in the axial direction of the suction passage or the discharge passage relative to the plunger coincides with the apex of the plunger at the top dead point, or is located in the direction of elevation of the plunger from the apex.   
     
     
         23 . The pump for supplying high-pressure fuel according to  claim 21 , wherein the gap formed between the outer periphery of the cylinder and the body in the radial direction is smaller than the gap formed in the radial direction between the inner diameter of the pressurizing chamber and the outer diameter of the plunger. 
     
     
         24 . The pump for supplying high-pressure fuel according to  claim 23 , wherein the gap formed between the outer periphery of the cylinder and the body in the radial direction is smaller than the gap formed in the radial direction between the outer periphery of the cylinder and the inner periphery of the holder member of the cylinder. 
     
     
         25 . The pump for supplying high-pressure fuel according to  claim 12 , wherein the holder member of the cylinder is composed of two members: a seal holder member having a sealing member therein for sealing low-pressure fuel, and an urging member for urging the cylinder to the body, and
 wherein the seal holder member is fitted to the urging member, and a gap is formed in the radial direction between the two members.