MXPA01000675A - Axle/adapter assembly for vehicle suspension and suspension incorporating same - Google Patents

Abstract

An axle (12) and adapter bracket (30) assembly alone and in combination with a suspension and comprising a lightly compressible spacer (48) between the two for a slight adjustment of the axle with respect to the axle bracket after the weld operation. Preferably, the axle and adapter bracket assembly comprises an axle adapter bracket having an arcuate surface (44) supporting the axle and an axle welded to the axle bracket along longitudinal surfaces of the adapter bracket. A lightly compressible spacer is provided between the adapter bracket and the axle. The lightly compressible spacer is preferably in the form of flexible elastomeric foam tape strips. A compressive connector, such as a U-bolt (38), can be used to compressively retain the axle to the axle adapter bracket and apply a compressive force that counter the residual tensile stress in the weld.

Description

AXLE / ADAPTER ASSEMBLY FOR SUSPENSION OF VEHICLE AND SUSPENSION THAT INCORPORATES IT Background of the Invention Field of the Invention This invention relates to suspension systems. In one of its aspects, the invention relates to a vehicle suspension system where an axle is welded to an axle adapter bracket and stress stresses in the weld between the axle and the adapter bracket are relieved. In another of its aspects, the invention relates to a suspension system in which an axle is mounted on a rear arm suspension by means of an axle adapter bracket. In still another aspect, the invention relates to a method for assembling an axle to an axle adapter bracket for use in a vehicle suspension. Description of Related Art Rear arm suspensions, such as that disclosed in U.S. Patent No. 5,112,078 to Galazin et al., Comprise a rear arm suspension where one axle is mounted on a pair of rear arms, each of which is pivotably mounted in an axle frame at one end through a hanging bracket and resiliently mounted on the axle at another end by an air spring. The shaft is typically mounted on a rear arm suspension by an adapter bracket that includes an arcuate surface to straddle the axle and weld to the axle. The adapter clamp is in turn mounted on the rear arm suspension, typically by sleeve gaskets. U-bolts can also be used to attach the shaft and the adapter clamp to the rear arm suspension. Welding the shaft to the adapter clamp tends to create stresses within the shaft and in the weld. In particular, the shaft is expanded during the welding operation. The shaft and the welding are cooled after the welding operation. The shrinkage of the weld during cooling causes residual stresses in the weld between the shaft and the adapter clamp. Previous attempts have been made to solve this problem but without any satisfactory solution. SUMMARY OF THE INVENTION According to the invention, an assembly of an axle and an adapter bracket has a highly compressible spacer between the two elements for a slight adjustment of the axle with respect to the axle clamp after the welding operation. Thus, according to the invention, an assembly of an axle and an adapter bracket comprises an axle adapter bracket having an arcuate surface supporting an axle and a shaft welded to the axle clamp along longitudinal surfaces of the axle. the adapter clamp. According to the invention, a slightly compressible separator is provided between the adapter clamp and the shaft. The slightly compressible separator is preferably in the form of strips of flexible elastomeric foam tape. The slightly compressible separator, or strips of flexible elastomeric foam tape, is placed on the U-shaped surface of the adapter clamp before mounting the shaft on the adapter clamp. The foam tape remains in place after welding the shaft to the adapter clamp. The foam tape remains in place after welding the shaft to the adapter clamp. The slightly compressible separator is compressed between the shaft and the U-shaped surface of the adapter clamp after the welding operation and after the welding and the shaft have cooled. The shrinkage between the shaft and the adapter clamp which normally results in residual stresses between the shaft and the adapter clamp is accommodated by compression of the compressible separator. The compressible separator is typically compressed only lightly by the weight of the shaft in the adapter clamp and is only compressed significantly when shrinkage of the weld occurs between the shaft and the adapter clamp. A compressive connector can be used to compressively connect the shaft to the shaft adapter clamp. The compressive connector applies a compression force to the weld that counteracts the residual stress stress in the weld. The magnitude of the compressive force can be large enough to overcome the residual stress stress in the weld and create a residual compressive force in the weld. In another aspect, the invention relates to a rear arm suspension comprising a pair of arms adapted to be pivotally mounted at one end to a vehicle frame with springs spaced from the other end of the arm resiliently holding the arms for resilient movement with respect to a frame of vehicle. The shaft adapter clamps are mounted on the arms and a shaft welded to the shaft adapter clamps. A slightly compressible separator is placed between the shaft adapter clamp and the shaft, thereby the post-weld shrinkage between the shaft and the shaft adapter clamp, which normally results in residual stresses between the shaft and the adapter clamp. axis, is accommodated by the compression of the compressible separator. In still another aspect, the invention relates to a method for mounting an axle to an axle adapter bracket for use in a vehicle suspension system, comprising the steps of: placing a lightly compressible separator between the axle and the adapter bracket of axis; solder the shaft to the shaft adapter bracket, and thereby heat the shaft and the shaft adapter bracket, at least in the area of the weld; and cooling the shaft and shaft adapter clamp while compressing the slightly compressible spacer between the shaft adapter clamp and the shaft to accommodate post-weld shrinkage between the shaft and the shaft adapter clamp. The method may further include the application of a compressive force between the shaft and the shaft adapter clamp to apply a compressive force to the weld. The compressive force can be large enough to overcome the residual tension stress in the weld and even create a compressive stress in the weld. DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a suspension system according to the invention, as mounted on a vehicle frame; Figure 2 is a perspective view of one of the sides of the suspension system shown in Figure 1; Figure 3 is a perspective view of an axle and an axle assembly assembly shown in Figures 1 and 2; and Figure 4 is a perspective view of an axle adapter clamp shown in the suspension systems of Figures 1-3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and to Figure 1 in particular, a vehicle frame 10 has a shaft 12 suspended therefrom by a suspension system 16 according to the invention. The front of the vehicle is on the right side of the frame, as shown in Figure 1. The suspension 16 includes, on each side of the vehicle frame 10, a rear arm 18 pivotally mounted in a frame bracket 20 that depends on the frame 10 in a pivotal mounting 22. Each rear arm 18 extends rearwardly of the vehicle frame 10 and away from its pivotal mounting 22 in a direction that is longitudinal to the vehicle frame 10. Each rear arm has an extension 24 that mounts a pedestal 26 of an air spring 28. An upper mounting plate 29 of the air spring 28 is secured to the vehicle frame 10. A pair of shock absorbers 35 joins pivotally between the rear arm 18 and an upper portion of the frame bracket 20. The shaft 12 is connected to each rear arm 18 by an adapter bracket of shaft 30 and connections with sleeve 31. As shown in Figures 2 and 3, the shaft adapter clamp 30 comprises a pair of mounting plates 32, each having a pair of openings that receive the c sleeve connection 31. The internal mounting plate 32 has a horizontal joining flange 36 through which a compression fitting, such as a U-bolt 38, compressively retains the shaft in the shaft adapter bracket. The U-bolt is secured by nuts 46 which are screwed into the ends of the U-bolt 38 in a conventional manner. Brackets 39 are secured between the internal mounting plate 32 and the joining flanges 36, preferably by welding, to reinforce the tie plates 36. A side clip 40 extends between the mounting plates 32 at its upper portion and defines a welding surface 41 (figure 4). The shaft 12 is welded to the adapter 30 by a welding bead 42 which extends along the surface 41 and longitudinally along the axis 12 on each side of the adapter. The adapter further has a U-shaped plate 44 having a central opening 46, as illustrated in Figure 4. As shown in Figure 4, a pair of flexible elastomeric foam tape strips 48 is mounted circumferentially on the surface of the U-shaped mounting plate 44 for resiliently separating the shaft 12 from the inner surface of the mounting plate 44. The foam tape 48 may be a single-sided or double-sided flexible foam tape such as, for example, the one manufactured by 3M. The foam tape is strong enough to separate the shaft from the inner surface of the U-shaped plate 44 when the shaft is straddled within the U-shaped plate 44 and before welding the shaft to the shaped plate. of U 44. It is desirable to adhere the tape only to the inner surface of the U-shaped plate 44. During welding of the shaft 12 to the shaft adapter bracket 30, the shaft and perhaps portions of the U-shaped plate 44 of the shaft adapter clamp will expand to some extent due to the heat of the weld. By cooling the weld, the shaft, the weld and perhaps portions of the U-shaped plate 44 will shrink and create a residual stress stress in the weld between the shaft and the adapter. However, as a result of the separation of the foam tape, the shaft can move closer to the inner surface of the U-shaped plate 44, thereby relieving or reducing the residual stress stress in the weld. The residual stress stress in the weld 42 resulting from shrinkage of the shaft during cooling is minimized significantly by the use of the foam tape. In addition to the foam tape, the U-bolt also helps to alleviate or further reduce the residual stress stress in the weld because the U-bolt applies a compression force to the weld which counteracts the residual stress in the weld. the welder. The stress of residual tension in the weld takes the shaft towards the shaft adapter clamp against the foam, to compress the foam and reduce the stress of residual stress. However, the foam tape is still capable of additional compression as the residual stress does not fully compress the foam. The tightening of the U-bolt further leads the shaft to the shaft adapter clamp to further reduce the residual stresses in the weld. The U-bolt can be tightened enough that the compressive force applied by the U-bolt to the weld exceeds the residual stress stress and even creates compressive stress in the weld. It has been found that the durability of the shaft increases significantly, up to three times, as a result of the use of the tape between the shaft and the U-shaped plate. The elimination of the residual stress stress by the compressive force applied by the U-bolt additionally increases durability since welding is much less feasible to fail under compression than under tension. Although the invention has been described with reference to a particular shaft adapter clamp and an axle, the invention can be used with any type of suspension where an axle is welded to an adapter clamp. In this way, the invention is not necessarily limited to rear arm suspensions, nor to the particular rear arm suspension disclosed in the description. Additionally, although the invention has been described with reference to foam tape that is adhesively secured to the arched plate 44, any type of compressible separator may be used slightly between the arched plate and the shaft. Resilient elastomeric strips or even elastomeric sheets may be placed on the arched plate 44 before the shaft 12 is placed there, as long as the separator deforms in a compressible manner upon cooling the weld. Similarly, compressive connectors other than a U-bolt may be used to compressively retain the shaft in the shaft adapter bracket. Variations and reasonable modifications are possible within the scope of the above disclosure and drawings, without departing from the spirit of the invention.

Claims (32)

1. CLAIMS 1. A shaft and clamp adapter assembly, comprising: an axle adapter clamp for supporting an axle; a shaft welded to the shaft adapter bracket; and a slightly compressible separator between the shaft adapter clamp and the shaft; whereby the post-weld shrinkage between the shaft and the shaft adapter clamp which normally results in residual stresses in the weld between the shaft and the shaft adapter clamp is accommodated by compression of the compressible separator.
2. 2. A shaft and adapter clamp assembly according to claim 1, wherein the slightly compressible spacer comprises a flexible elastomeric foam sheet material.
3. 3. A shaft and adapter clamp assembly according to claim 2, wherein the flexible elastomeric foam sheet material is adhesively secured to the shaft adapter clamp.
4. 4. A shaft and adapter clamp assembly according to claim 3, wherein the compressible separator is substantially not compressed by the weight of the shaft in the shaft adapter clamp and is compressed upon shrinkage occurring between the shaft and the shaft adapter clamp. after the welding operation.
5. 5. A shaft and adapter clamp assembly according to claim 1, wherein the shaft is welded to the shaft adapter clamp along the longitudinal surfaces of the shaft adapter clamp.
6. 6. A shaft and adapter clamp assembly according to claim 1, wherein the compressible separator is substantially not compressed by the weight of the shaft in the shaft adapter clamp and is compressed upon shrinkage occurring between the shaft and the adapter clamp. axis after the welding operation.
7. 7. A shaft and adapter clamp assembly according to claim 1, wherein the compressible layer comprises multiple strips of a thin layer of an elastomeric material.
8. 8. A shaft and adapter clamp assembly according to claim 1, and further comprising a compression fitting that integrally assembles the shaft in the shaft adapter bracket, whereby the compression assembly of the shaft in the shaft adapter clamp applies a compressive force to the welding in opposition to the stress of residual tension in the welding.
9. 9. A shaft and adapter clamp assembly according to claim 8, wherein the compressive connector applies a compressive force to the weld, of sufficient magnitude to counteract the residual stress stress in the weld and create a compressive stress in the weld. the welder.
10. A shaft and adapter clamp assembly according to claim 8, wherein the compressive connector is a U-bolt that at least partially surrounds the shaft and is connected to the shaft adapter clamp.
11. A rear arm suspension, comprising a pair of arms adapted to pivotally mount at one end to a vehicle frame and mounting springs spaced apart from the said end of the arm to resiliently support the arms for resilient movement with respect to a frame of vehicle; adapter arm clamps mounted on the arm; and a shaft welded to the shaft adapter clamps and extending between the arms; the improvement comprising: a separator slightly compressible between the shaft adapter clamp and the shaft; whereby the post-weld shrinkage between the shaft and the shaft adapter clamp which normally results in stresses in the weld between the shaft and the shaft adapter clamp is accommodated by compression of the compressible separator.
12. 12. A rear arm suspension according to claim 11, wherein the slightly compressible separator comprises a flexible elastomeric foam sheet material.
13. 13. A rear arm suspension according to claim 12, wherein the flexible elastomeric foam sheet material is adhesively secured on a surface of the shaft adapter bracket.
14. 14. A rear arm suspension according to claim 13, wherein the compressible separator is substantially not compressed by the weight of the shaft in the shaft adapter clamp and is compressed upon shrinkage occurring between the shaft and the shaft adapter clamp after the welding operation.
15. 15. A rear arm suspension according to claim 11, wherein the shaft is welded to the shaft adapter clamp along longitudinal surfaces of the adapter clamp of e.g.
16. 16. A rear arm suspension according to claim 11, wherein the compressible separator is substantially not compressed by the weight of the shaft in the shaft adapter clamp and is compressed upon shrinkage occurring between the shaft and the shaft adapter clamp after the welding operation.
17. 17. A rear arm suspension according to claim 11, wherein the compressible separator comprises multiple strips of a thin layer of an elastomeric material.
18. 18. A method for mounting an axle in an axle adapter bracket for use in a vehicle suspension system, comprising the steps of: placing a lightly compressible separator between the axle and the axle adapter bracket; solder the shaft to the shaft adapter clamp and thereby heat the shaft and the shaft adapter clamp, at least in the area of the weld; and cooling the shaft and the shaft adapter clamp while compressing the slightly compressible spacer between the shaft adapter clamp and the shaft to accommodate the post-weld shrinkage between the shaft and the shaft adapter clamp.
19. A method for mounting an axle in an axle adapter bracket, according to claim 18, wherein the slightly compressible spacer comprises a flexible elastomeric foam sheet material.
20. A method for mounting an axle in an axle adapter bracket, according to claim 19, wherein the step of placing the spacer slightly compressible between the axle and the axle adapter bracket comprises adhesively applying strips of foam sheet material flexible elastomer to the flexible adapter clamp and with this place the shaft on the shaft adapter clamp.
21. 21. A method for mounting an axle to an axle adapter bracket, according to claim 20, wherein the axle adapter brackets have an arcuate surface and the axle rests on the arcuate surface of the adapter bracket of e.g.
22. 22. A method for mounting an axle to an axle adapter bracket, according to claim 21, wherein the compressible separator is substantially not compressed by the weight of the axle in the axle adapter bracket before the welding step.
23. 23. A method for mounting an axle to an axle adapter bracket, according to claim 22, and further comprising the step of applying a compressive force between the axle and the axle adapter bracket where the compressive force is in opposition to the force of tension in the welding.
24. 24. A method for mounting an axle to an axle adapter bracket, according to claim 23, wherein the compressible separator is further compressed by the compressive force applied by the compressible assembly to further accommodate the tension stress in the weld.
25. 25. A method for mounting an axle to an axle adapter clamp, according to claim 24, wherein the magnitude of the compressive force is large enough to overcome the tension stress in the weld and create a compressive stress in the weld.
26. 26. A method for mounting an axle to an axle adapter bracket, according to claim 25, wherein the compressive force is applied by a U-bolt connecting the axle to the axle adapter bracket.
27. 27. A method for mounting an axle to an axle adapter bracket, according to claim 18, wherein the step of placing the spacer slightly compressible between the axle and the axle adapter clamp comprises adhesively applying the compressible separator to the adapter clamp. of the shaft and then place the shaft on the shaft adapter clamp.
28. 28. A method for mounting an axle to an axle adapter bracket, according to claim 27, wherein the axle adapter bracket has an arcuate surface and the axle rests on the arcuate surface of the adapter bracket of eg.
29. 29. A method for mounting an axle to an axle adapter bracket, according to claim 27, wherein the compressible separator is substantially not compressed by the weight of the axle in the axle adapter bracket before the welding step.
30. 30. A method for mounting an axle to an axle adapter bracket, according to claim 18, wherein the compressible layer comprises multiple strips of a thin layer of an elastomeric material.
31. 31. A method for mounting an axle to an axle adapter bracket, according to claim 18, wherein the compressible separator is substantially uncompressed prior to the welding step.
32. 32. A method for mounting an axle to an axle adapter bracket, according to claim 18, and further comprising the step of applying a compressive force between the axle and the axle adapter bracket, where the compressive force is in opposition to the Tension stress in welding.