Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
1996-01-26
2001-09-18
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
Reexamination Certificate
active
06290396
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a steering assembly for a vehicle and, more specifically, to a steering assembly having a deformable sleeve bearing for preventing foreign matter from affecting normal steering operations.
BACKGROUND OF THE INVENTION
Steering assemblies include, generally, a tubular housing configured to receive a correspondingly configured steering shaft arranged for rotatable movement within the tubular housing. Typically, the steering shaft is longer than its corresponding tubular housing wherein a portion of the steering shaft extends upward beyond the tubular housing's upper end for mounting a steering wheel. The other end of the steering shaft extends beyond the opposing or lower end of the tubular housing and extends, in a conventional vehicle, behind the dashboard or other wall defining the interior space of the vehicle body. The lower end of the steering shaft is then coupled to the steering mechanism associated with the vehicle wheels. Thus, rotational motion applied to the steering wheel may be transferred to the steering mechanism to steer the vehicle.
In most vehicles, such as domestic automobiles, the steering assembly is enclosed within the dashboard or other wall defining the interior space of the automobile. Thus, there is minimal or no threat that foreign matter such as debris may enter the steering assembly and affect its operability. Some vehicles, however, include an open body design such as racing cars. These vehicles generally do not include aesthetic features included in domestic vehicle designs such as walls defining the interior vehicle space for obscuring the mechanical components of the automobile from view. The aesthetic appearance of the car's interior is often not considered in racing car designs for several reasons including the unnecessary weight and costs involved.
Accordingly, foreign matter such as dirt and debris may contact the steering assembly in some vehicles, particularly racing cars. When the foreign matter enters the tubular housing, it may interfere with the normal operation of the steering assembly by preventing relative rotational movement between the steering shaft and the tubular housing. For instance, debris may become wedged between the steering shaft and the tubular housing thereby locking up the steering wheel and hence, the entire vehicle steering mechanism. The dangers and the need to avoid this occurrence are readily apparent.
The steering assemblies of prior art racing cars often include a pair of remotely spaced metal brackets for supporting the steering shaft. It may be the instance that the metal brackets are used in place of a tubular housing and therefore independently support the steering shaft. Thus, a metal-to-metal connection is defined by the metal steering shaft and the metal bracket. When foreign matter such as dirt or debris enters the vehicle compartment, it may become lodged within the steering assembly and interfere with the steering shaft's ability to rotate. If the foreign matter interferes with the rotational metal to metal connection of the steering shaft and bracket, the steering of the vehicle may be interrupted and even halted. Indeed, there is a need to prevent interruption of the steering mechanism by foreign matter contacting, as it will in racing cars, the steering assembly of the vehicle.
Prior art attempts have been made to provide improved mountings for the steering shafts within steering assemblies. These attempts do not, however, provide preventative measures for the aforementioned problems experienced particularly in vehicles such as racing cars. For example, U.S. Pat. No. 4,098,141 to Yamaguchi is directed to an energy absorbing steering assembly whereby the steering shaft is telescopically arranged within the steering column so that the steering assembly is collapsible upon impact. A collision at the front of the vehicle would cause relative movement in the axial direction between the steering shaft and the steering column. This relative movement is restricted during normal operation by a bearing supporting the upper end of the shaft. Impact against the steering wheel by the operator of the vehicle causes the steering shaft and column to move downwardly. The downward movement is prevented during normal operation by shear pins which are sheared upon impact, thereby permitting the steering assembly to collapse.
A prior art bearing for supporting the steering shaft is described in U.S. Pat. No. 2,622,690 to Barenyi. According to that patent, a bearing or sleeve is provided at the upper end of the steering shaft for supporting the shaft within the steering column. This arrangement is positioned within a housing. The Barenyi patent is directed to a steering assembly for use in a domestic automobile wherein the steering shaft is mounted, at its lower end, behind a wall defining the interior of the vehicle body. Although an upper bearing is provided, it merely supports the upper end of the shaft within the steering column and is itself protected from contact with foreign matter by the additional housing.
These and other prior art steering assemblies have many shortcomings and limitations which significantly restrict their usefulness in open vehicle body designs, such as racing cars, for preventing dirt or debris from interfering with the vehicles normal steering functions.
SUMMARY OF THE INVENTION
The present invention overcomes the shortcomings of the prior art and provides an apparatus and a steering assembly which is well suited to effectively prevent interference of the vehicle's normal steering operation by foreign matter such as dirt or debris.
More particularly, according to one embodiment of the invention, the apparatus includes an elongate metal steering shaft, a tubular housing, and a sleeve bearing. The tubular housing encloses a portion of the length of the steering shaft and is adapted to be fixed to the frame of a motor vehicle. At least one sleeve bearing is interposed between the steering shaft and the tubular housing for rotatably supporting the steering shaft. The sleeve bearing is formed of a polymeric material having a predetermined hardness which is substantially less than the hardness of the steering shaft. Therefore, in the event abrasive foreign matter enters between the steering shaft and the sleeve bearing, the sleeve bearing will be deformed or destroyed and binding between the steering shaft and the bearing is thereby precluded.
In another embodiment of the present invention, the steering assembly includes a steering shaft, a tubular housing and two sleeve bearings. The sleeve bearings are interposed between the steering shaft and the tubular housing adjacent each of the ends of the tubular housing for rotatably supporting the steering shaft. In this embodiment also, each of the sleeve bearings are formed of a polymeric material having a predetermined hardness which is substantially less than the hardness of said steering shaft.
REFERENCES:
patent: 948800 (1910-02-01), Symmonds, Jr.
patent: 1555214 (1925-09-01), Johnson
patent: 1572519 (1926-02-01), Davis
patent: 2622690 (1952-12-01), Barenyi
patent: 2683637 (1954-07-01), Skillman, Jr. et al.
patent: 3521501 (1970-07-01), Kiekhaefer
patent: 4098141 (1978-07-01), Yamaguchi
patent: 4415166 (1983-11-01), Beia
patent: 4517854 (1985-05-01), Kawabata et al.
patent: 4726695 (1988-02-01), Showalter
patent: 4808015 (1989-02-01), Babcock
patent: 5192137 (1993-03-01), Renard
patent: 0719695 (1957-07-01), None
patent: 1007998 (1963-11-01), None
Deutschman, Aaron D., et al., Machine Design Theory and Practice, pp. 438-439, Dec. 1975.
600 Racing, Inc.
Fitzpatrick ,Cella, Harper & Scinto
Hannon Thomas R.
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