Patent Application
20060043785
The subject invention relates to a vehicle wheel disc having a disc flange portion with a groove located to reduce tension at a weld attachment interface to a rim.
A vehicle wheel disc includes a disc flange that is first press fit into a rim and then welded to the rim at a weld interface to form a vehicle wheel. The disc flange includes an outer surface that directly abuts against an inner surface of the rim. The outer and inner surfaces are generally linear and abutment occurs along a substantial portion of the length of the disc flange.
In order to provide high robustness, the disc flange traditionally has at least one flange portion with an increased thickness. A typical flange thickness at this flange portion is at least four (4) millimeters but can vary depending upon vehicle load and application. One problem with this increased thickness is that there is no allowance for flexing movement of the disc flange. The direct abutment between the disc flange and the rim at the outer and inner surfaces, in combination with the increased thickness, further prohibits flexing movement.
The inability of the disc flange to flex results in an accumulation of tension at the weld interface between the vehicle wheel disc and the rim. The accumulation of tension increases weld stress and can generate premature cracking at the weld interface. This adversely affects the fatigue life of the vehicle wheel.
Thus, there is a need for a vehicle wheel disc having a disc flange portion that can flex as needed to reduce stress at the weld interface between the vehicle wheel disc and the rim.
A vehicle wheel includes a wheel disc with a disc flange portion that extends to a distal edge. A weld area is located on the disc flange portion at the distal edge. A groove is formed within the disc flange portion at a location that is spaced apart from, i.e. remote from, the weld area.
In one example, the groove includes a curved surface with an apex that extends into the disc flange portion. The disc flange portion has a variable thickness with a first flange portion near the distal edge having a first predetermined thickness and a second flange portion at the apex having a second predetermined thickness. The second predetermined thickness is preferably greater than the first predetermined thickness. Both the first and second predetermined thickness are preferably less than four (4) millimeters, but can vary depending on vehicle load and application.
A rim is attached to the wheel disc at the weld area, forming a weld interface. The groove is formed within the disc flange portion to allow flexing movement of the disc flange portion relative to the rim. The flexing movement reduces tension exerted on the weld interface, which improves the overall performance and fatigue life of the vehicle wheel.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
A vehicle rim and wheel assembly 10 is shown in
The rim 14 includes an upper surface 18 that faces a tire (not shown) and a lower surface 20. The wheel disc 12 includes an outer surface 22 that abuts against the lower surface 20 of the rim 14 and an inner surface 24. The wheel disc 12 includes a vertically extending disc portion 26 and a disc flange portion 28 that extends outwardly to a distal peripheral edge 30. The weld attachment interface 16 is located at the distal peripheral edge 30.
As shown in
The disc flange portion 28 includes a first portion 36 at the weld attachment interface 16 and a second portion 38 that transitions into the vertically extending disc portion 26. The groove 32 is spaced apart, i.e. remotely located, from the weld attachment interface 16 at the second portion 38. A generally linear surface 40 extends from the groove 32 to the first portion 36.
The rim 14 is fixed to the disc flange portion 28 at a first rim portion 42 and is spaced apart from the disc flange portion 28 at a second rim portion 44. The weld attachment interface 16 is located at the first rim portion 42.
The disc flange portion 28 includes a variable thickness. The disc flange portion 28 has as first flange thickness adjacent to the first portion 36 and a second flange thickness at the apex 34. The second flange thickness is preferably greater than the first flange thickness. Also, both the first and second flange thickness are preferably less than four (4) millimeters. In one example, the first flange thickness is two and one-half (2.5) millimeters and the second flange thickness is three (3) millimeters. This is significantly less than the traditional flange thickness, which is at least four (4) millimeters. While this configuration is preferred, it should be understood that the flange thickness could be varied, i.e. increased or decreased, depending on vehicle load and application.
As discussed above, the rim 14 is attached to the wheel disc 12 at the weld attachment interface 16. After attachment, a recess 46 is formed at the second rim portion 44 between the lower surface 20 of the rim and the upper surface 22 of the wheel disc 12 at the groove 32. The reduced thickness of the disc flange portion 28 in combination with the groove 32 allows the second portion 38 of the disc flange portion 28 to flex or move relative to the rim 14.
The flexing movement removes tension from the weld attachment interface 16 and transfers tension to other areas in the wheel disc 12. Consequently, the fatigue life and component performance significantly increases compared to prior designs. Further, the number and size of weld cracks are significantly reduced, which leads to the improved fatigue performance.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
