Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
  • B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
  • B62D5/22—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for rack-and-pinion type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
  • B62D5/062—Details, component parts

Definitions

• the present invention relates to an apparatus for sealing a fluid chamber, and particularly to apparatus for sealing a fluid chamber of a fluid power assisted rack and pinion steering gear.
• U.S. Patent No. 5, 181,581 describes a rack bushing made from a hard plastic material. A resilient lip seal is connected with the bushing for sealing between the bushing and the rack.
• the present invention is a hydraulic power assist rack and pinion steering gear comprising a tubular housing partially defining a chamber for receiving fluid under pressure.
• a rack extends axially through the chamber in the housing.
• An annular bushing supports the rack for axial movement in the chamber.
• the bushing has a cylindrical inner surface defining a passage extending longitudinally through the bushing for receiving the rack therethrough.
• the bushing has a groove in the inner surface defined by a bottom surface and two end surfaces.
• a seal assembly is received in the groove for sealing between the rack and the bushing.
• the seal assembly includes a first seal member located in the groove in sealing engagement with the bottom surface of the bushing.
• the seal assembly includes a second seal member located in the groove in sealing engagement with the first sealing member and with the rack. The second seal member is disposed radially between the first seal member and the rack.
• Fig. 1 is a schematic illustration of a fluid power assisted rack and pinion steering gear with parts cut away and constructed in accordance with the present invention
• Fig. 2 is an enlarged view of a portion of Fig. 1 showing a rack bushing and seal assembly in accordance with the present invention
• Fig. 3 is a further enlarged view of a portion of the assembly of Fig. 2.
• the present invention relates to an apparatus for sealing a fluid chamber, and particularly to apparatus for sealing a fluid chamber of a fluid power assisted rack and pinion steering gear.
• the present invention is applicable to various steering gear constructions.
• Fig. 1 illustrates a fluid power assisted rack and pinion steering gear 10.
• the steering gear 10 is connected with a pair of steerable vehicle wheels (not shown) in a known manner by steering linkage 12 at one end of the steering gear and by steering linkage (not shown) at the opposite end 14 of the steering gear.
• the steering gear 10 includes a housing 16, a pinion 18, and a rack 20.
• the rack 20 has an outer surface 28 and extends longitudinally through a tubular portion 22 of the housing 16.
• the tubular housing portion 22 partially defines a fluid chamber 24.
• a piston (not shown) is fixed to the rack 20 at a location within the chamber 24.
• An annular bushing 30 supports the rack 20 for axial movement relative to the housing 16.
• the bushing 30 is preferably injection molded of a plastic material suitable for use in the environment of a hydraulic fluid power assisted rack and pinion steering gear.
• the bushing 30 could, alternatively, be made from another material, such as aluminum.
• the bushing 30 has parallel, cylindrical inner and outer side surfaces 32 and 34, which extend parallel to the axis 26.
• the inner side surface 32 defines a passage 36 through which the rack 20 extends .
• a snap ring groove 38 is formed in the outer surface 34 of the bushing 30.
• a snap ring 40 is received in the groove 38.
• the snap ring 40 engages in a corresponding groove 42 in an inner surface of the housing 16 to lock the bushing 30 in position axially in the housing. Any other known bushing retention method could be used in place of the snap ring 40.
• An annular seal groove 50 (Fig. 3) is formed in the inner surface 32 of the bushing 30.
• the seal groove 50 has a generally rectangular cross sectional configuration defined by a bottom surface 52 and spaced end surfaces 54 and 56.
• the bottom surface 52 has a cylindrical configuration centered on the axis 26 at a location spaced radially outward from the rack 20.
• Each one of the end surfaces 54 and 56 has an annular configuration centered on the axis 26.
• a seal assembly 60 is received in the seal groove 50, in the bushing 30, for sealing between the bushing and the rack 20.
• the seal assembly 60 includes a first seal member 62 and a second seal member 64.
• the first seal member 62 is located in the groove 50, in sealing engagement with the bottom surface 52 of the groove.
• the second seal member 64 is located in the groove 50, in sealing engagement with the outer surface 28 of the rack 20.
• the first seal member 62 is disposed between the second seal member 64 and the bottom surface 52 of the groove 50.
• the second seal member 64 is disposed between the first seal member 62 and the outer surface 28 of the rack 20.
• the first seal member 62 is an annular O-ring and the second seal member 64 is an engineered plastic sealing ring.
• the O-ring 62 is made from a resilient material such as neoprene and when in its free state has a round cross-sectional configuration.
• the O-ring 62 has an outer surface 63.
• the second seal member 64 is an annular member made from a material such as Vespel® brand plastic, or glass reinforced PTFE, or graphite reinforced PTFE.
• the second seal member 64 has a generally rectangular cross-sectional configuration including parallel inner and outer surfaces 66 and 68 and parallel end surfaces 70 and 72.
• Both the seal ring 64 and the O-ring 62 are narrower (axially) than the groove 50.
• the inner surface 66 of the seal ring 64 seals against the outer surface 28 of the rack 20.
• the outer surface 68 of the seal ring 64 seals against the outer surface 63 of the 0- ring 62.
• the outer surface 63 of the O-ring 62 seals against the bottom surface 52 of the groove 50.
• the O-ring 62 deforms under this fluid pressure, and the outer surface 63 of the O-ring is pushed firmly against the bottom surface 52, the end surface 56 of the bushing 30 and surface 68 of seal ring 64.
• the deformation of the O-ring 62 also helps to push the seal ring 64 radially inward against the outer surface 28 of the rack 20. Therefore, the seal ring 64, as backed up by the O-ring 62, seals even better against the outer surface 28 of the rack 20. As a result, an improved seal is effected between the rack 20 and the bushing 30 by the seal assembly 60.
• a second (optional) seal assembly 60a identical to the seal assembly 60, is provided.
• the second seal assembly 60a is located in a second seal groove 50a.
• the second seal groove 50a is spaced axially from the seal groove 50.
• the seal grooves 50 and 50a are preferably located as close as feasible to the axial center of the bushing 30.
• Providing two seal assemblies 60 and 60a can help to improve the sealing function of the rack bushing 30.
• the invention can be used with one, two or more seal assemblies, depending on the application. From the foregoing description of the invention, those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Sealing Devices (AREA)
• Power Steering Mechanism (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=23123535

Family Applications (1)

Country Status (3)

Families Citing this family (1)

Family Cites Families (9)

• 2002
  • 2002-05-16 AU AU2002339882A patent/AU2002339882A1/en not_active Abandoned
  • 2002-05-16 EP EP02744284A patent/EP1395480A4/de not_active Withdrawn
  • 2002-05-16 WO PCT/US2002/018487 patent/WO2002095269A2/en not_active Ceased

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