Brakes – Internal-resistance motion retarder – Including seal or guide
Reexamination Certificate
1999-09-13
2001-11-20
Graham, Matthew C. (Department: 3613)
Brakes
Internal-resistance motion retarder
Including seal or guide
C277S352000, C277S353000, C277S437000, C277S439000
Reexamination Certificate
active
06318526
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to a rod guide and seal assembly for vibration damping devices, and more particularly, to a compliant rod guide and seal assembly for dampers used in shock absorbing systems.
BACKGROUND OF THE INVENTION
Shocks, struts and other damping devices are used in shock absorbing systems to dissipate vibrational and other forces. In vehicle shock absorbing systems, such damping devices are used to absorb shock loads sustained by the wheel assemblies of such vehicles and are used in combination with coil springs. Damping devices typically operate by transmitting the applied forces to a rod and piston combination slidably mounted in a fluid-filled chamber of an inner tube of the damper. As the piston is urged through the chamber, the fluid in the chamber is forced through and around the piston. The resistance of the piston to movement through the fluid in the chamber is directly proportional to the applied force. In this manner the movement of the rod and piston, and thereby the applied forces, are damped.
Strut or shock type dampers may include a rod guide assembly that guides and centers the rod and piston as they reciprocate within the inner tube. When lateral or “side load” forces are applied to the damper, the rod and piston may be shifted away from the radial center of the damper. Furthermore, deviations in tolerances in the various components of the damper can also shift the rod and piston off center. Radial misalignment of the rod and piston within the damper causes the rod to rub against the rod guide as it reciprocates within the inner tube, which increases wear on the rod and rod guide. This is especially undesirable in dampers containing magnetorheological fluid, the suspended magnetic particles of which can be abrasive to the rod. Furthermore, when the rod is laterally displaced, the rod can engage and laterally displace the rod guide, which in turn shifts the inner tube from the radial center of the damper. The shift in position of the inner tube increases wear upon various bearings, seals, and sleeve supports in the damper.
In order to prevent undue wear to a damper piston rod, some struts are provided with an outer tube bearing a bracket adjacent its lower end for attachment to a vehicle wheel suspension assembly and which is closed at its lower end by a strut base. One end of the piston rod is fixed to the middle of the strut base, and the rod projects upward into an inner tube containing the piston and fluid. The top of the inner tube is fixed to the vehicle body, so that the rod and piston thus move axially together with the outer tube and wheel assembly in opposition to the inner tube and vehicle body. Side loads applied to the strut are received by bearing elements between the inner and outer tubes; and very little of these side loads are thus applied to the rod. But apparatus must be provided to close and seal the bottom of the inner tube against loss of working fluid; and this assembly must accommodate the stroking action of the rod therethrough. This apparatus includes a rod guide and seal assembly, which, although relieved of most of its side loads, still includes a bearing and seal in contact with the rod. The rod guide and seal assembly thus provides a third point of radial support for the rod between the point of attachment to the strut base at the bottom and the piston at the top. If manufacturing tolerances or other factors cause the rod guide to be laterally misaligned with these other supports, it may cause undesirable wear between itself and the rod. Accordingly, there is a need for a rod guide and seal assembly that can accommodate manufacturing tolerances in lateral alignment with other rod support apparatus while providing secure sealing around an axially moving rod to maintain the working fluid within the working chambers of the damper.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a compliant rod guide and seal assembly for a rod and piston damping device that can accommodate lateral misalignment with respect to the rod without increasing the wear upon the rod and other damper components, and a compliant rod guide and seal assembly which is sufficiently rugged and durable to be used in automotive applications. When incorporated in a strut or other damper, the compliant rod guide and seal assembly can move laterally relative to the inner tube to align with other rod support members. The rod bearing and seal in the guide are thus able to operate as designed with minimum friction and wear. In a preferred embodiment, the compliant rod guide and seal assembly includes an annular outer casing defining a through hole, and a support ring received in the outer casing. The support ring has an outer radius that is less than the inner radius of the outer casing such that a gap is formed between the support ring and the outer casing. The rod guide and seal assembly further includes a rod seal mounted in the support ring which is shaped to receive and form a seal with a rod extending therethrough. The ring and seal can move radially relative to the outer casing to accommodate lateral movement of the rod.
Other objects and advantages of the present invention will be apparent from the following description, the accompanying drawings and the appended claims.
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Kruckemeyer William Charles
Oliver Michael Leslie
Delphi Technologies Inc.
Graham Matthew C.
Sigler Robert M.
Williams Thomas J.
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