Patent Application
20090108667
The present teachings relate to a molded vehicle wheel having an integral hub and hub sub-assembly.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Most land vehicles include two or more wheels on which pneumatic tires are mounted to provide a rolling surface for movement of the vehicle. For example, many known light-weight utility vehicles, such as small cargo/maintenance vehicles, shuttle vehicles or golf cars, include three or more wheels, at least one of which is mounted on a wheel shaft of the vehicle suspension. Generally, such wheels have a two-part steel construction including an outer rim and an inner rim that are welded together to form the wheel on which the tire is mounted and inflated.
To mount the wheel and tire assembly on the wheel shaft of the vehicle, typically two conical bearings are mounted on the shaft and a hub assembly is mounted over the bearings. The hub assembly typically includes a wheel mounting plate welded to, or formed with, a cylindrical hub that is mounted over the bearings. Once the hub assembly is mounted over the bearings, the hub assembly is rotatably secured to the shaft. The wheel mounting plate typically includes a plurality of threaded studs that are spaced to match holes in the wheel. Therefore, the wheel, with the mounted tire, can be mounted on the hub assembly by inserting the threaded studs through the holes in the wheel. Wheel mounting nuts are then threaded onto the threaded studs to secure the wheel and tire to the hub, which is rotatably secured to the shaft.
Such known multi-part wheel and hub assemblies are costly and time consuming to assemble.
A unitary wheel and hub assembly is provided. In accordance with various embodiments, the wheel and hub assembly includes a molded wheel having a hub integrally molded therewith. The wheel and hub assembly additionally includes a hub sub-assembly integrally formed with the hub to form a unitary wheel and hub assembly that can be directly rotatably mounted on a wheel shaft of a vehicle.
Further areas of applicability of the present teachings will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present teachings in any way.
The following description is merely exemplary in nature and is in no way intended to limit the present teachings, application, or uses. Throughout this specification, like reference numerals will be used to refer to like elements.
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The outer sleeve 46 is constructed to provide radial support to the hub 38 and stability to the wheel 34 and hub 38 during operation of the vehicle 10. More particularly, the outer sleeve 46 distributes radial and side loads across the hub 38 that are imparted on the hub 38 by the weight of the vehicle 10 and forces generated during operation of the vehicle 10. The outer sleeve 46 can be fabricated of any material having suitable strength and having any suitable dimensions to support and distribute the forces exerted on the hub 38.
For example, in various embodiments the outer sleeve 46 can be fabricated of steel or other suitable metal. In other various embodiments, the outer sleeve 46 can be fabricated of a suitable high strength plastic or composite having a wall thickness suitable for supporting and distributing such forces. The outer sleeve 46 is integrally formed, or joined, with the hub 38 such that the inner sleeve 46 can not be removed or separated from the hub 38 once the outer sleeve 46 is formed, or joined, with the hub 38. In various embodiments, the outer sleeve 46 can be press fit into the hub 38, while in other embodiments, the outer sleeve 46 can be molded into the hub 38.
In still other embodiments, the wheel 34 and hub 38 can be molded of high strength plastic or composite with the hub 38 having a wall thickness suitable for supporting and distributing such radial load and torque forces imparted on the hub 38 by the weight of the vehicle 10 and operation of the vehicle 10.
The inner sleeve 50 is constructed to bear the compression load between the bearings 54 when the wheel and hub assembly 14 is mounted and secured on the wheel shaft 22, as described below. The inner sleeve 50 can be fabricated of any material having suitable strength and dimensions to bear the compressive forces imparted on the inner sleeve when the nut 30 is tightened onto the shaft 22 to secure the wheel and hub assembly 14 on the shaft 22. For example, in various embodiments the inner sleeve 50 can be fabricated of steel or other suitable metal. In other various embodiments, the inner sleeve 50 can be fabricated of a suitable high strength plastic or composite having a wall thickness suitable for bearing such compression loads.
The bearings 54 can be any bearing suitable for use within a vehicle wheel hub, such as hub 38. For example, in various embodiments, the bearings 54 are sealed bearings having an inner race 66 and an outer race 70 that are pressed into the outer sleeve 46. In various implementations, the outer sleeve 46 includes a raised shoulder 72 integrally formed with, and extending radially inward from, an interior portion of the outer sleeve 46. The bearings 54 are pressed into the outer sleeve 46 until the bearings 54 are stopped by the raised shoulder 72. That is, when the bearings 54 are pressed into the outer sleeve 46, the outer races 70 will be stopped by and abut opposing ends 74 and 78 of the raised shoulder 72. The raised shoulder 72 has a predetermined longitudinal, or axial, length L, i.e., the longitudinal distance between the opposing ends 74 and 78, that spaces the bearing 54 apart at the specified length L. The shoulder 72 also positions the bearings 54 a predetermined distance from a center line of the wheel 34, thereby providing a proper balance of stresses imparted on the hub 38 and outer sleeve 46 during operation of the vehicle 10.
Additionally, the inner sleeve 50 has a predetermined longitudinal, or axial, length M, i.e., the longitudinal distance between the opposing ends 60 and 62. In accordance with various embodiments, the length M of the inner sleeve 50 is slightly shorter, e.g., 8/1000 of an inch to 12/1000 of an inch shorter, than the length L of the shoulder 72. When the unitary wheel and hub assembly 14 is mounted on the wheel shaft 22, threading and tightening the nut 30 onto the threaded shaft end 26 will retain the unitary wheel and hub assembly 14 on the shaft 22. More particularly, tightening the nut 30 onto the shaft 22 will force the inner races 66 of the bearings 54 axially inward, i.e., toward each other. Thus, tightening the nut 30 onto the shaft 22 with the wheel and hub assembly mounted on the shaft 22, will compress the inner races 66 axially inward and into abutment with the opposing ends 60 and 62 of the inner sleeve 50.
Therefore, since the length M of the inner sleeve 50 is slightly shorter than the length L of the outer sleeve shoulder 72, when the unitary wheel and hub assembly 14 is mounted and secured on the shaft 22, the inner races 66 will be aligned slightly axially inward from the outer races 70. This slight offset in alignment of the inner and outer races 66 and 70 preloads the bearings 54. Preloading the bearing 54 causes the bearings 54 and the hub 38 to operate as a single unit, thereby improving performance and reliability of the unitary wheel and hub assembly 14.
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Each of the low-friction bushings 94 includes an inner leg 98 and an outer leg 102. In various embodiments, the low-friction bushings 94 are pressed into opposing ends of the wheel hub 38 such that the inner legs 98 extend into an interior portion of the wheel hub 38 and the outer legs 102 abut outer end surfaces 104 of the wheel hub 38. In other embodiments, the low-friction bushing 94 can be molded into the ends of the wheel hub 38.
The bushing spacer sleeve 96 is similar in design and functions as the bearing spacer sleeve 50, described above. That is, the bushing spacer sleeve 96 has a predetermined longitudinal, or axial, length that is slightly shorter, e.g., 8/1000 of an inch to 12/1000 of an inch shorter, than a distance D between distal ends of the inner legs 98 of the opposing bushings 94. When the unitary wheel and hub assembly 14 is mounted on the wheel shaft 22, threading and tightening the nut 30 onto the threaded shaft end 26 will force the inner legs 98 of the bushings 94 axially inward, i.e., toward each other. Thus, tightening the nut 30 onto the shaft 22 with the wheel and hub assembly 14 mounted on the shaft 22, will compress the inner legs 98 axially inward and into abutment with the opposing ends of the bushing spacer sleeve 96. This preloads the bushing 94 much in the same way as the bearing 54 are preloaded, as described above, thereby causing the bushings 94 and the hub 38 to operate as a single unit and improving performance and reliability of the unitary wheel and hub assembly 14.
When the wheel and hub assembly 14 is mounted on the shaft 22, the bushing inner legs 98 lightly contact the outer surface of the shaft 22. However, the bushing spacer sleeve 96 has thickness T that is slightly less than a thickness S of the bushing inner legs 98. Thus, although the bushing inner legs lightly contact the outer surface of the shaft 22, a small space, or gap, will exist between the shaft 22 and the bushing spacer sleeve 96. For example, the space between the shaft 22 and the bushing spacer sleeve 96 can be 0.5 mm to 1.0 mm. In various embodiments, the low-friction bushings 94 include a metal core 106 plated, or coated, with a low-friction material 110 such that the wheel and hub assembly 14 will rotate on the shaft 22 in a substantially frictionless manner. For example, in an exemplary embodiment, the low-friction bushings 94 comprises a steel core 106 having a Teflon® coating 110.
The description herein is merely exemplary in nature and, thus, variations that do not depart from the gist of that which is described are intended to be within the scope of the teachings. Such variations are not to be regarded as a departure from the spirit and scope of the teachings.
