MXPA06001924A - Split outer tube anti-walkout bushing - Google Patents

Abstract

A pivot bushing for a suspension system has an inner metal and a split outer metal with an elastomeric bushing disposed between the metals. The split outer metal has one end which is partially closed by an inwardly curved portion and one end which is open. The assembly of the bushing is through the open end. Once assembled the open end is closed by placing a cover over the open end and crimping the cover to a flange formed at the open end. In another embodiment, the cover is inserted into the outer metal and the split outer metal is crimped to secure the cover in place.

Description

ANTI-STOP BEARING OF DIVIDED EXTERNAL PIPE Field of the Invention The present invention relates to a device that secures a spring to a vehicle for use in suspension systems for trucks, buses and the like. More particularly, the present invention relates to an improved bearing design that functions as an interface between a leaf spring and the attachment point on the frame for the leaf spring. BACKGROUND OF THE INVENTION Truck and bus suspensions are commonly designed using a pair of leaf springs between both the front and rear axles of the vehicle (the non-elastic portion), and the vehicle body (the elastic portion). The leaf springs are usually a plurality of steel or composite sheets, arched in shape, which are stacked together to form the leaf spring. The axle of the vehicle is normally secured to the approximate center of the arched leaves with the end of the leaves extending upwards. The upstream end of the leaves is usually formed with a tubular section or ring, which is adapted to receive a pivot bearing of the spring.

The spring pivot bearing usually consists of an outer metal housing which is depressed in the spring ring Ref.170124, an elastomer layer placed inside the outer metal housing and an internal metal housing extending through the center of the layer of the elastomer. A screw extends through the inner metal and secures the end of the leaf spring to the chassis or elastic portion of the vehicle by engagement with the appropriate support plate. When the vehicle travels, the relative movement between the elastic and non-elastic portions of the vehicle is accommodated by the flexing of the leaf springs. The flexing of the leaf springs causes the ends of the leaf springs to oscillate on both of the tubular sections or rings securing the leaf spring to the elastic portion of the vehicle. The pivot bearings of the spring are used to facilitate this oscillating movement and to isolate the vehicle from shocks. The elastomer layer located between the inner and outer housings effectively insulates the elastic portion of the vehicle from the non-elastic portion of the vehicle. In certain high load applications, the ends of the outer metal are bent at the top towards the inner metal to further encapsulate the elastomer layer. The curvature of the ends and consequently the additional encapsulation of the elastomer layer improves the radial elasticity rate, improves the axial elasticity rate, improves the axial retention and improves the durability of the bearing. Although these pivot bearings insulated with elastomer have worked satisfactorily in the field, they are not without problems. The various problems associated with these pivot bearings of the prior art include variations in the diameters of the ends of the spring and the distortion of the cross section in the area where the pivot bearing is depressed at the ends of the spring. These manufacturing variations in the configuration of the spring end frequently allow the bearing to slide out of the spring when the spring suffers an axial load. Also, in higher load applications, it is common for the outer metal to split due to high loads. This separation of the external metal can be avoided by the heat treatment of the external metal. However, the outer metal in higher load applications must remain soft to be bent upward. Therefore, with curved end bearings, heat treatment of the complete bearing is not a possibility. Another option to improve the resistance of the external metal is to manufacture the external metal from a tube stretched on mandrel (DOM) which is of a superior resistance. Although this DOM tube will increase the strength of the pipe, it will also significantly increase manufacturing costs associated with the pivot bearing.

Accordingly, the continuous development of the pivot bearings has been directed to the improvement of performance, strength and durability while minimizing the manufacturing costs associated with the pivot bearing. Summary of the Invention The present invention provides the craft with a pivot bearing that provides improved performance of the double-ended curved bearings while still allowing the use of the outer metal of the lower cost stretched outer layer. The present invention includes a split outer metal having one end bent towards the inner metal with the other end forming a projection extending radially outwardly. A separate stamping may be attached to the end with protrusions to provide compression and restraint for the elastomer. The external metal of the present invention can be manufactured from a stretched outer layer material of low cost and because of its split configuration which is oriented towards the spring splice gap, the high point charge stresses are avoided because of The split outer metal design allows very small radial deflections of the outer metal. Other advantages and objects of the present invention will become apparent to those skilled in the art from the following detailed description, the appended claims and the figures. Additional areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are proposed for purposes of illustration only and are not intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description and the appended figures, wherein: Figure 1 is a typical rear suspension for a vehicle incorporating the single pivot bearing according to the present invention; Figure 2 is an enlarged end view showing the end of the leaf spring and the pivot bearing shown in Figure 1; Figure 3 is a cross-sectional view of the pivot bearing shown in Figure 1; Figure 4 is a perspective view of the pivot bearing shown in Figure 1 without the cover; Figure 5 is a cross-sectional view of a high load pivot bearing of the prior art; Figure 6 is a cross-sectional view of a pivot bearing according to another embodiment of the present invention; and Figure 7 is an end view of the pivot bearing shown in Figure 5. Detailed Description of the Invention The following description of the preferred embodiment (s) is (are) only exemplary (s) in its nature and are not proposed in any way to limit the invention, its application, or uses. Referring now to the figures in which like reference numerals designate like or corresponding parts in all the various views, there is shown in Figure 1 a further truck or bus suspension incorporating the single bearing according to the present invention and the which is generally designated by the reference numeral 10. The rear suspension 10 comprises a chassis 12, a propeller shaft 14 and a pair of springs 15. The chassis 12 supports a bodywork (not shown) and other vehicle components that are generally identified as the "elastic mass". The drive shaft 14 includes a differential 20 that receives the torque of a motor (not shown) through a rotary drive shaft (not shown). The drive shaft 14 also includes a pair of hollow tubes 22 which extend outwardly to a respective wheel assembly (not shown). Placed inside each of the tubes 22 is a motor shaft 26 extending to a hub (not shown) to which it is attached to a wheel (not shown). The motor transmits the rotation and the torque to the differential 20 by means of the drive shaft. The differential 20 transfers the rotation and torque from the drive shaft to the drive shafts 26 to rotate and thereby drive the wheels of the vehicle. The springs 16 are positioned between the chassis 12 and the propeller shaft 14 as will be described hereinafter. Additionally, a shock absorber 28 is placed between each track of the chassis 12 and the drive shaft 14 to dampen movement between these two components. A bar for transmitting the torque (not shown) can be placed between the chassis 12 and the drive shaft 14 to assist in controlling the movement of the drive shaft 14 with respect to the chassis 12. Referring now to FIGS. 1 and 2 , the springs 16 are each fixed to a respective tube 22 using a plate 40 of the spring and a pair of clamps 42 of the spring. The front edge of each spring 16 is fixed to a support plate 44 fixed to the chassis 12. A pivot bearing 46 is positioned between the spring 16 and the support plate 44 to accommodate movement between two components and to isolate the vehicle from the shocks. The back curve of each spring 16 is fixed to a shackle 50 which is positioned between the chassis 12 and the rear curve of each spring 16. A pivot bearing 46 can be placed between the spring 16 and the shackle 50 and a pivot bearing 46 it can be placed between the shackle 50 and the chassis 12 to accommodate movement between these components and to isolate the vehicle from shocks. Although the present invention is being illustrated having only one pivot bearing 46 positioned between the spring 16 and the chassis 12, it is within the scope of the present invention to have two or possibly three or more pivot bearings positioned between the spring 16 and the chassis 12 if is desired Further, although the present invention is being described as possibly having three identical pivot bearings 46 positioned between the spring 16 and the chassis 12, it is within the present invention to use a different design for each bearing position if desired. Finally, although the present invention is being illustrated having the shackle 50 placed between the rear part of the spring 16 and the chassis 12, it is within the scope of the present invention to have a shackle 5 placed between the front curve of the spring 16 and the chassis 12 or between both of the front and rear curves of the spring 16 and the chassis 12 if desired. Referring now to Figures 2 and 3, the pivot bearing 46 comprises an inner metal 60, an elastomeric bearing 62 and an outer metal assembly 64. The inner metal 60 includes a generally cylindrical central section 66 and a pair of sections 68 generally rectangular, a section 68 is positioned at each end of the central section 66. Each rectangular section 68 has an opening 70 extending therethrough, which is used to secure the pivot bearing 46 to the appropriate support plate. Although the central section 66 is illustrated as a generally cylindrical, solid section, it is within the scope of the present invention to use a tubular internal metal design, a ball-shaped bolt or any other design, if desired. If a tubular inner metal is used, generally the rectangular sections 68 can be eliminated and a through screw can be used to secure the pivot bearing to the chassis. The elastomeric bearing 62 is an annular element which is positioned between the inner metal 60 and an external metal assembly 64. The free diameter of the elastomeric bearing 62 is larger than the space between the inner metal 60 and the outer metal assembly 64 in such a way that a specified percentage compression is applied to the elastomeric bearing 62 when it is assembled in the pivot bearing 46. The mounting of the pivot bearing 46 can be effected by first attaching the elastomeric bearing 62 to the inner metal 60 and then inserting this combination into the external metal assembly 64. Another method of mounting the pivot bearing 46 could be to first join the elastomeric bearing into the outer metal assembly 64 and then inserting the inner metal 60 into the elastomeric bearing 62 if desired. The present invention provides advantages for both assembly methods. The elastomeric bearing can be attached to either the internal metal 60 or the external metal assembly 64, may be attached to both the internal metal assembly 60 and external metal assembly 64 or may not be attached to the internal metal assembly 60 or to the external metal assembly 64. The external metal assembly 64 comprises a body 76 in the shape of a divided cup. and a cover 78. The divided cup-shaped body 76 includes a divided annular wall 80 which has a portion 82 curved inward at one end and a projection 84 extending outwardly at the opposite end. The divided annular wall 80 may also include an optional stepped portion 86 to compensate for distortion of the spring. The cup-shaped body 76 is assembled on the elastomeric bearing 62. Because the projection 84 extends outwardly, the elastomeric bearing 62 can always be assembled from this end with projections. Accordingly, the inwardly curved portion 82 and outwardly extending projection 84 can be formed prior to mounting the split cup shaped body 76 and the elastomeric bearing 62. This, therefore, provides the opportunity to deal with heat and therefore reinforcing the cup-shaped body 76 prior to being assembled with the elastomeric bearing 62. To increase the strength of the pivot bearing 46 for use in high load applications, the elastomeric bearing 62 must be encapsulated or restricted Additionally. The elastomeric bearing 62 is a generally non-compressible fluid. Accordingly, by encapsulating the elastomeric bearing 62 further, the cup of elasticity and consequently the load bearing characteristics of the pivot bearing 46 are increased. The prior art method for encapsulating the elastomeric bearing is shown in Figure 4 which illustrates a bearing 100 of the prior art. The bearing 100 includes an internal metal 102, an annular elastomeric bearing 104 and an outer metal 106. As can be seen, in Figure 4, the elastomeric bearing 104 is further encapsulated having an inwardly curved portion 108 located at both ends of the metal Outer 106. Although this two curved portion formation 108 effectively encapsulates the elastomeric bearing 104, the formation of these curved portions 108 can only be effected by forming them after assembly with the elastomeric bearing 104. If the curved portions 108 are formed prior to the assembly with the elastomeric bearing 104, the assembly of the two components is extremely difficult if not impossible. Accordingly, it is not possible to effectively heat the external metal 106 prior to assembly with the elastomeric bearing 104 since it must remain soft and ductile for the formation of the curved portions 108. It is also not possible to effectively heat the external metal 106 afterwards. of assembly due to deterioration of the elastomeric bearing 104. Referring again to FIGS. 2 and 3, the present invention overcomes this obstacle with prior art by the use of a body 76 in the form of a divided cup and cover 78. As stated above , the end with protrusions of the body 76 in the form of a divided cup always allows the assembly of the body 76 in the form of a divided cup and the elastomeric bearing 62. Once these two components are assembled, the cover 78 is secured to the body 76 in the shape divided cup to complement the encapsulation of the elastomeric bearing 62. The cover 78 is an annular element having a portion ring 90, a contoured portion 92 'and a plurality of curved portions 94 extending radially outwardly. The portion 90 of the ring is positioned adjacent the projection 84 and the curved portions 94 are bent around the projection 84 as shown in Figure 3 to secure the cover 78 to the cup-shaped body 76. The contoured portion 92 provides the coupling surface to the elastomeric bearing 62 and will therefore control the spring rate for the pivot bearing 46 by controlling the encapsulation and flow of the elastomeric bearing 62. Another advantage associated with the pivot bearing 46 is that the pivot bearing 46 will limit the axial movement of the pivot bearing 46 with respect to the spring 16 in a direction due to the projection 84 and the cover 78. Because the axial load for a pivot bearing is significantly higher in one direction, the pivot bearing 46 can be assembled to the spring 16 in the appropriate direction such that the projection 84 and the cover 78 resist the significantly higher axial load. In certain high load applications, tubular or undivided outer metal bearings are subject to fatigue failure of the outer metal due to high point load voltages. The configuration for the curved end or the spring rings within which the bearings are assembled, can be distorted, out of round shape and / or not totally circumferential. In these cases, the outer metal will suffer fatigue due to the high point charge voltage caused by the shape of the ring. For example, in the manufacture of a coiled steel spring, the steel is wound onto a coil to form an opening or ring 110 (see Figure 2) in which the pivot bearing 46 is inserted by tightening fit. It is between the end of the steel casing and the lower end of the spring leaving an opening 112 in which the ring 110 of the spring does not complement a total circumference. The opening 12 is commonly referred to as a gap for splicing. Typically, the opening 112 or the gap for the splice is located in the vertical plane of the vehicle. Both static and dynamic loads are transferred through the vertical plane of the vehicle. Although the opening 112 or the gap for the splice are typically located in the vertical plane, the opening 112 is not limited to the vertical plane and the opening 112 may be located in other positions with respect to the vehicle such as, but not limited to, the longitudinal or lateral plane of the vehicle. When an undivided tubular bearing is inserted into the ring 110 of the spring, the gap for the splice 102 creates point contact along a line where the ring 110 of the spring does not support the outer metal. It is these point contacts, typically in the vertical plane, which subject the undivided tubular bearing to high load stresses and cause longitudinal fatigue fractures on the undivided outer metal. The cup-shaped body 76 is designed to withstand the high load stresses applied by the point load of the spring ring 110. The cup-shaped body 76 includes a longitudinal division 116 that will allow very small radial deflections of the cup-shaped body 76 to reduce and / or eliminate the body 76 in the form of a divided or stressed cup. As shown in Figure 2, the partition 116 is designed to be oriented relative to the splice gap 112 in the ring 110 of the coiled spring. In addition, the orientation of the division 116 can be placed in other areas deemed necessary in other spring rings or in other applications using the pivot bearing 46. Although the body 76 in the form of a divided cup is illustrated having a single longitudinal division 116, it is within the scope of the present invention include a plurality of divisions 116 that are considered necessary for the particular application. In addition, the division 116 does not necessarily have to be a straight longitudinal division, it could also be of the oscillating type or it could still be circumferential depending on the given application. In certain applications it is desirable to use a design without projections for the pivot bearing. Figures 5 and 6 illustrate a pivot bearing 146 according to another embodiment of the present invention. The pivot bearing 146 comprises the inner metal 60, the elastomeric bearing 62 and an outer metal assembly 164. Accordingly, the pivot bearing 146 is the same as the pivot bearing 46 except that the outer metal assembly 64 is replaced with the mounting of external metal 164. The outer metal assembly 164 comprises a divided cup-shaped body 176 and a retaining ring or cover 178. The divided cup-shaped body 176 includes a split 116 and an annular wall 180 having a portion curve in 182 at one end. The divided cup-shaped body 176 is assembled on the elastomeric bearing 162. Because the end of the divided cup-shaped body 176 opposite the inwardly curved portion 182 is generally straight and open, the elastomeric bearing 62 can always be assembled from this open end. Accordingly, the inwardly curved portion 182 can be formed prior to mounting the split cup-shaped body 176 and the elastomeric bearing 62. This, therefore, provides the opportunity to heat treat and thereby reinforce the body 176 with divided cup shape prior to being assembled with the elastomeric bearing 62. Once the divided cup shaped body 176 and the elastomeric bearing 62 are assembled, the retaining ring 178 is inserted into the open end of the shaped body 176 of divided cup adjacent the elastomeric bearing 62 and the open end of the divided cup-shaped body 176 is bent or deformed into a plurality of sites 184 to ensure that the retaining ring 178 within the cup-shaped body 176 is divided. The retaining ring 178 provides a coupling surface to the elastomeric bearing 62 and will therefore control the cup of elasticity of the pivot bearing 46 by controlling the encapsulation and flow of the elastomeric bearing 62. This design only requires that the shaped body 176 of divided cup is rolled or deformed into a plurality of sites 184. The open end of the divided cup-shaped body 176 is not required to form an outline similar to that of the curved inward portion 182. The retaining ring 178 forms the contour similar to portion 92. Accordingly, the demand for a soft and ductile end could require that the open end of the divided cup-shaped body 176 not be heat treated, is not present in this design. The open end of the divided cup-shaped body 176 only needs to be soft and ductile enough to be rolled or deformed to retain the retaining ring 178. The above description about division 116, its advantages and its various configurations also applies to pivot bearing 146. Although the above detailed description describes the preferred embodiment of the present invention, it should be understood that the present invention is susceptible to modification, variation and alteration without departing from the scope and correct meaning of the appended claims. The description of the invention is only of exemplary nature and, therefore, variations that do not depart from the object of the invention are considered within the scope of the invention. Such variations are not going to be considered as a deviation from the spirit and scope of the invention. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (18)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property. A pivot bearing, characterized in that it comprises: an internal metal; an external metal placed on the inner metal, the outer metal defines a division; and an elastomeric bearing placed between the inner metal and the split outer metal.
2. 2. The pivot bearing according to claim 1, characterized in that the external element has an inwardly curved portion at a first end and a generally cylindrical portion extending from the first end to a second open end, the open end is equal to, or is larger in diameter than the generally cylindrical portion.
3. 3. The pivot bearing according to claim 2, characterized in that the division extends through the first end and the generally cylindrical portion.
4. 4. The pivot bearing according to claim 2, characterized in that it further comprises a cover secured to the outer metal to close the second open end.
5. The pivot bearing according to claim 4, characterized in that the cover is placed inside the outer metal.
6. The pivot bearing according to claim 5, characterized in that the cover is secured to the outer metal by the flange formed in the outer metal.
7. 7. The pivot bearing according to claim 1, characterized in that the division extends over a longitudinal extension of the external metal.
8. 8. The pivot bearing according to claim 1, characterized in that it further comprises a cover secured to the outer metal.
9. The pivot bearing according to claim 1, characterized in that the open end defines a projection extending outwards.
10. The pivot bearing according to claim 9, characterized in that a cover is positioned adjacent to the projection extending outwards.
11. The pivot bearing according to claim 10, characterized in that the cover comprises a ring portion positioned adjacent to the projection and a folded portion securing the cover to the projection.
12. 12. The pivot bearing according to claim 11, characterized in that the cover includes a contoured portion for closing an open end of the outer metal.
13. The pivot bearing according to claim 9, characterized in that the division extends through the projection extending outwards.
14. The pivot bearing according to claim 9, characterized in that the external element has a portion extending inwardly at a first end and the projection extending outward at a second end, a generally cylindrical portion extending from the first end to the second end, the second open end is equal to, or larger in diameter than, the generally cylindrical portion.
15. The pivot bearing according to claim 14, characterized in that the division extends through the first end through the generally cylindrical portion and through the projection extending outwardly.
16. 16. The pivot bearing according to claim 14, characterized in that a cover is positioned adjacent to the outwardly extending projection. The pivot bearing according to claim 16, characterized in that the cover comprises a ring portion positioned adjacent the projection and a folded portion securing the cover to the projection. The pivot bearing according to claim 17, characterized in that the cover includes a contoured portion for closing an open end of the outer metal.