Seal mechanism and fuel pump provided therewith
AssigneeHitachi, Ltd.
InventorsMinoru Hashida, Hideki Machimura, Hideaki Yamauchi, Masayoshi Kotaki, Takefumi Yamamura
Life of this patent
Estimating the term…
Abstract
A seal mechanism with improved pressure tightness is provided to eliminate a return piping to a fuel tank used for reducing pressure applied to the seal mechanism in a high pressure fuel pump. The seal mechanism includes a stress reduction mechanism for reducing the stress generated at the junction between its retaining member and flexible member.
Claims18
A seal mechanism, comprising a retaining member having a cylindrical portion configured for mounting the seal mechanism on a body and an annular surface portion for receiving pressure of a pressurized fluid by cooperation with a sealing member, the annular surface portion having an inner periphery facing a sealing surface spaced therefrom with a gap at an innermost peripheral portion thereof, and a flexible member molded in one piece with the retaining member and having a flexible tip to perform a sealing function such that under the pressure of the pressurized fluid the flexible member is pushed against a pressurized-fluid side surface of the annular surface portion including an edge portion of the retaining member, wherein the retaining member is provided with a stress reduction mechanism only in a corner thereof;
- for reducing the stress generated in said flexible member the corner having a predetermined radius and being located within said flexible member at a side thereof to which the pressure of the pressurized fluid is applied to the sealing member, and the edge portion is formed at a side subjected to a lower pressure than the pressure side.
A high pressure fuel pump comprising a reciprocating plunger, and a cylinder which is slip-fitted with the plunger and in which a variable-volume pressurizing chamber is formed with the reciprocating motion of said plunger, wherein said fuel pump is provided with a seal mechanism at a periphery of the plunger at which the seal mechanism seals two fluids of a pressurized fuel and a lubricant oil of lower pressure than the pressurized fuel mutually at a sealing surface of the plunger, the seal mechanism comprising a retaining member having a pressurized fuel sealing portion and a lubricant oil sealing portion, with a common space of the fuel and oil provided between the sealing portions, a sealing member molded with the retaining member and pushable against a sealing surface by a pressure of the pressurized fuel being provided at a pressure-receiving side edge portion of the retaining member in the pressurized fuel sealing portion, and the pressure-receiving side edge portion of the inner peripheral portion facing the sealing surface of the pressurized-fuel sealing portion has a surface configured as a stress reduction mechanism to relieve a contact stress with the sealing member in which a curved portion of the surface is formed at only a corner at a side exposed to the pressurized fuel to reduce contact stress of the retaining member and an edge portion is formed in the corner at a side exposed to the lubricant oil.
Dependencies are inferred from the claim text.