Patent ID: 8573112

Claim:
A high-pressure fuel pump comprising: a plunger reciprocating within the pump; a housing having the plunger passing therethrough; and a seal system for separating/sealing of fuel and lubricating oil as sealing objects, the seal system being located in an annular space between the plunger reciprocating within the pump and the housing having the plunger passing therethrough, wherein the seal system includes: a recessed seal mounting part provided on an inner periphery of the housing at the fuel side, a fuel-side seal mounted in the seal mounting part at the fuel side for sealing of fuel, a recessed seal mounting part provided on an inner periphery of the housing at the lubricating oil side, and a lubricating-oil-side seal mounted in the seal mounting part at the lubricating oil side for sealing of lubricating oil, wherein the fuel-side seal is composed of a plastic seal ring and an elastomeric O ring for backup of the seal ring, wherein the lubricating-oil-side seal includes a single body of a single-lip-type oil seal, having an elastomeric seal lip fitted to a metal ring and arranged toward the lubricating oil side, and a distance between the fuel-side seal and the lubricating-oil-side seal is larger than a reciprocating motion distance of the plunger, and wherein the elastomeric O ring tightly contacts a tapered inner surface of the housing having a diameter gradually reducing from the lubricating oil side toward the fuel side.