Sealing device

Abstract

A high performance sealing device having an excellent pressure resistance and realizing a prevention of damage. The sealing device usable at a working pressure of 0 to 2 MPa, and not damaged. even if the pressure of high-pressure fuel of 5 MPa or higher is applied thereto, wherein high pressure fuel on the high pressure side H is sealed by a first seal part 2, oil from a cam side on a low pressure side L is sealed by a second seal part 3, and the fuel slightly leaked due to failure of scraping at the first seal part is sealed by the second seal part to form a dual seal structure, and a resin ring 21 coming into slidable sealing contact with a shaft 10 is used in the first seal part 2, whereby abnormal abrasion does not occur even when fuel having less lubricity is used, and the durability of the seal is increased.

1 . A fuel pump comprising:
 a housing,   a reciprocating shaft located in the housing,   a sealing device for sealing an annular gap formed between the reciprocating shaft and the housing, said sealing device including a sealing part including a resin sealing member coming into slidable sealing contact with a surface of the shaft, and an urging member for urging the resin sealing member toward the surface of the shaft, the sealing part sealing the side to be sealed where fuel exists, and a squeeze packing disposed on the side of the sealing part opposite to the side to be sealed for sealing fuel depressurized at the sealing part and lubrication oil which exists on the opposite side of where fuel exists, a distance between the sealing part and the squeeze packing being longer than a reciprocating stroke of the shaft to prevent the fuel sealed by the sealing part from entering the squeeze packing, and the squeeze packing being a U-packing.   
   
   
       2 . A fuel pump comprising:
 a housing,   a reciprocating shaft located in the housing,   a sealing device for sealing an annular gap formed between the reciprocating shaft and the housing, said sealing device including a first sealing part located in a stepped portion at an end of the housing, said first sealing part including a first resin sealing member in sliding sealing contact with a surface of the shaft; and a first urging member for urging the first resin sealing member toward the surface of the shaft, the first sealing part sealing a high pressure side to be sealed where fuel exists between the housing and the shaft, a second sealing part disposed in the stepped portion at an end of the housing on a side of the first sealing part opposite to the side to be sealed for sealing fuel between the housing and the shaft, the second sealing part including a sealing member sealing a low pressure side to be sealed where oil exists between the housing and the shaft, and a seal retainer having a recess for accommodating the sealing member of the second sealing part, and the seal retainer having a surface defining an accommodating space for accommodating the first sealing part between the surface of the seal retainer and a surface of the stepped portion of the housing.   
   
   
       3 . A fuel pump comprising:
 a housing,   a reciprocating shaft located in the housing,   a sealing device for sealing an annular gap formed between the reciprocating shaft and the housing, said sealing device including a sealing part including a resin sealing member coming into slidable sealing contact with a surface of the shaft, and an urging member for urging the resin sealing member toward the surface of the shaft, the sealing part sealing a side to be sealed where fuel exists, and   oil seals disposed on a side of the sealing part opposite to the side to be sealed for sealing fuel depressurized at the sealing part,   the oil seals being a rubber-like resilient body on a metal ring.   
   
   
       4 . The pump according to  claim 3 , wherein the oil seals are mounted using the metal ring fitted around an outer periphery of the housing. 
   
   
       5 . The fuel pump according to  claim 4 , further comprising a U-packing disposed on the side to be sealed of the oil seals. 
   
   
       6 . The pump according to  claim 3 , wherein the oil seals are mounted using the metal ring fitted around an inner periphery of the housing. 
   
   
       7 . The fuel pump according to  claim 3 , wherein the oil seals include two oil seals that are mounted using the metal ring fitted around an inner periphery and outer periphery of the housing, respectively, and a distance between tips of seal lip portions of both of the oil seals is shorter than a reciprocating stroke of the shaft, and thus lubricating oil spreads over both of the oil seals. 
   
   
       8 . The fuel pump as claimed in  claim 2 , wherein said second sealing part includes a second resin sealing member in sealing contact with the surface of the shaft and the second resin sealing member is urged by a second urging member toward the surface of the shaft. 
   
   
       9 . The fuel pump as claimed in  claim 8 , wherein said seal retainer surrounds said second urging member on three sides. 
   
   
       10 . The fuel pump as claimed in  claim 2 , wherein said first resin sealing member is a ring having opposite identical flat surfaces with one of said flat surfaces in contact with said shaft. 
   
   
       11 . The fuel pump as claimed in  claim 9 , wherein said second resin sealing member is a ring. 
   
   
       12 . The fuel pump as claimed in  claim 9 , wherein said seal retainer is U-shaped.