Sealing device

• US 8,348,639 B2
• Filed: 03/28/2007
• Issued: 01/08/2013
• Est. Priority Date: 06/04/2001
• Status: Active Grant

• Current Assignee: NOK Corporation
• Original Assignee: NOK Corporation
• Inventors: Okada, Masatoshi, Taira, Iwao, Abiko, Tadashi, Kondo, Yosuke, Takeno, Kazuki, Yamane, Ichiro
• Primary Examiner(s): Kramer, Devon
• Assistant Examiner(s): BAYOU, AMENE SETEGNE
• Application Number:
  US11/727,763
• Publication Number:
  US 20070169621A1
• Time in Patent Office: 2,113 Days
• Field of Search: 417/539, 417/423.9, 417/423.11, 417/423.14, 417/439, 277/566, 277/591, 277436-439, 277/510, 277/530, 277/908, 123/495, 921/68
• US Class Current: 417/423.11
• CPC Class Codes: F02M 59/442 means preventing fuel leakage around pump plunger, e.g. fluid barriers
• CPC Class Codes: F04B 53/164 Stoffing boxes
• CPC Class Codes: F16J 15/002 comprising at least two sealings in succession F16J15/162, F16J15/40 take precedence
• CPC Class Codes: F16J 15/3204 with at least one lip
• CPC Class Codes: F16J 15/3208 provided with tension elements, e.g. elastic rings
• CPC Class Codes: F16J 15/3232 having two or more lips
• CPC Class Codes: F16J 15/3236 with at least one lip for each surface, e.g. U-cup packings

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 is sealed by a first seal part, oil from a cam side on a low pressure side is sealed by a second seal part, 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. A resin ring coming into slidable sealing contact with a shaft is used in the first seal part, whereby abnormal abrasion does not occur even when fuel having less lubricity is used, and the durability of the seal is increased.

Claims

1. A high pressure fuel pump for pressurizing fuel to a high pressure in an engine of an in-cylinder direct injection system, the fuel pump comprising a reciprocating shaft, a housing with an aperture, through which the shaft reciprocates, and a sealing device for sealing an annular gap formed between the reciprocating shaft and the housing, the sealing device comprising

a first sealing part including a resin sealing member in slidable sealing contact with a surface of the shaft, and an O-ring urging member for urging the resin sealing member toward the surface of the shaft, the first sealing part sealing a side to be sealed where fuel exists,

the resin sealing member being from a tetrafluoroethylene group, the O-ring urging member being one of fluorinated rubber and acrylic rubber,

a second sealing part including a squeeze packing and a U-shaped seal retainer,

said second sealing part being disposed on a side of the first sealing part opposite to the side to be sealed for sealing fuel depressurized at the first sealing part and lubrication oil which exists on the opposite side of where fuel exists, said squeeze packing being in slidable sealing contact with the surface of the shaft,

said U-shaped seal retainer engaging the housing and being located between the housing and the shaft and extending towards the shaft, said U-shaped seal retainer forming a first mounting groove in conjunction with the housing, said first mounting groove receiving said first sealing part fitted therein, said U-shaped seal retainer forming a second mounting groove, said second mounting groove receiving said squeeze packing therein, and

said squeeze packing being an X-ring, a distance between two lips of the X-ring coming into contact with the shaft being shorter than a reciprocating stroke of the shaft, the X-ring being one of fluorinated rubber and acrylic rubber,

an axial distance between the first sealing part and the squeeze packing being longer than a reciprocating stroke of the shaft to prevent the fuel sealed by the first sealing part from entering the squeeze packing,

said first sealing part and said second sealing part being located in a single cavity of the housing.

2. The fuel pump according to claim 1, wherein a contact surface of the resin sealing member with the shaft is a tapered surface towards a side of the squeeze packing with an axial center of the tapered surface projecting towards the shaft.

3. The fuel pump according to claim 1, wherein a contact surface of the resin sealing member with the shaft is a tapered surface towards a side to be sealed where fuel exists so that the tapered surface deviates from the shaft as the tapered surface gets close to the side to be sealed where fuel exists.

4. The fuel pump according to claim 1, wherein a working pressure of the fuel pump is 2 MPa or higher.

5. The fuel pump according to claim 1, wherein a working pressure of the fuel pump is 5 MPa or higher.