ROTATIONALLY SLIPPING RUBBER BUSHING WITH AXIAL RETENTION FEATURE

A bushing is provided having an outer rigid portion and an inner rigid portion concentrically arranged around each other, the inner rigid portion being the innermost component, a flexible portion positioned between the inner rigid portion and the outer rigid portion, the flexible portion configured to space apart the outer rigid portion and the inner rigid portion and each of the outer rigid portion, the inner rigid portion and the flexible portion includes a tapered end configured to connect with a fastener.

FIELD OF THE INVENTION

The present invention relates generally to bushings. More particularly, the present invention relates to a bushing adapted for use in leaf spring eyes.

BACKGROUND OF THE INVENTION

Current rubber bushings typically used in leaf springs are made of a rubber over molded inner metal and an outer metal. The assembly is press fit into the outer metal and then the outer metal is roll crimped inward at its distal ends. The bushing is then press fit into its location in the vehicle (typically a leaf spring eye) where it is rigidly connected to the rest of the vehicle via a bolt and a nut. Movement of the vehicle causes relative motion between the molded assembly (the rubber bonded to the inner metal) and the outer metal. For proper vehicle performance, the bushing must accommodate the loads in its radial and longitudinal or axial directions as well as rotation about its longitudinal axis, herein referred to as the torsional direction. Current bushings of the prior art can handle radial and torsional loads sufficiently, but lack an adequate axial retention feature. A longitudinal load can cause the rubber to deform around the outer metal's crimp and allow the molded assembly to become dislodged at relatively low loads (less than 5 kN).

The assembly of the prior art as illustrated typically includes an elongated and an inner metal portion. The inner metal portion includes an over molded rubber positioned between the inner metal and the outer metal. The outer metal is crimped at each of its distal ends. This configuration causes the rubber to deform around the outer metal and allows the assembly to become dislodged.

Accordingly, there exists a need in the art to overcome this deficiency while achieving the ideal rotational compliance. While achieving the ideal rotational compliance of zero has proven to require a more complex concept, there exists a need in the art to provide axial retention. A lack of axial retention forces manufacturers to design the bushings for higher rotational compliances which result in poor vehicle performance.

SUMMARY

In one embodiment, a bushing is provided having an outer rigid portion and an inner rigid portion concentrically arranged around each other, the inner rigid portion being the innermost component, a flexible portion positioned between the inner rigid portion and the outer rigid portion, the flexible portion configured to space apart the outer rigid portion and the inner rigid portion and each of the outer rigid portion, the inner rigid portion and the flexible portion includes a tapered end configured to connect with a fastener.

The flexible portion may be a bonded rubber where the bonded rubber bonded to at least one of the outer rigid portion or the inner rigid portion. The bonded rubber of the flexible portion may include a textured outer surface where the textured outer surface positioned adjacent to an inner surface of the outer rigid component. An outer surface of the flexible portion includes a plurality of ridges positioned adjacent to an inner surface of the outer rigid component. The outer metal portion includes a main cylindrical section extending to tapered end. The rigid inner portion and the rigid outer portion are made from a material selected from the following: metal, plastic and/or polymer.

In one embodiment, the flexible portion is a rubber, the outer rigid portion is metal and the inner rigid portion is metal where the rubber of the flexible portion is bonded to at least one of the outer rigid portion and the inner rigid portion. The outer rigid portion is concentrically arranged around the flexible portion, the flexible portion is concentrically arranged around the inner rigid portion wherein each of the outer rigid portion, the flexible portion and the inner rigid portion include a central bore, the inner rigid portion configured to receive the fastener.

In another embodiment, a bushing assembly is provided having a first component and a second component. The first component has a first outer metal portion, a first inner metal portion and a first rubber portion concentrically arranged around each other, the first rubber portion spacing apart the first outer metal portion from the first inner metal portion. At least one of the first outer metal portion, the first inner metal portion and the first rubber portion having a first tapered end. The second component has a second outer metal portion, a second inner metal portion and a second rubber portion concentrically arranged around each other, the second rubber portion spacing apart the second outer metal portion from the second inner metal portion. At least one of the second outer metal portion, the second inner metal portion and the second rubber portion having a second tapered end. A fastener configured to connect the first tapered end of the first component and the second tapered end of the second component, the first component and the second component configured to at least partially overlap wherein the bushing assembly forms a bottleneck shaped center portion when fully assembled.

The first and second outer metal portions are concentrically arranged around the respective first and second rubber portions. Further, the first and second rubber portions are concentrically arranged around the respective first and second inner metal portion. The first and second inner metal portions are configured to receive the fastener.

In one embodiment, a rubber of the first rubber portion is bonded to at least one of the first outer metal portion or the first inner metal portion. Further, a rubber of the second rubber portion is bonded to at least one of the second outer metal portion or the second inner metal portion. The bonded rubber of the rubber portion includes a textured outer surface, the textured outer surface positioned adjacent to an inner surface of the outer metal component. In another embodiment, an outer surface of the rubber portion includes a plurality of ridges where the plurality of ridges positioned adjacent to an inner surface of the outer metal component.

In another embodiment, a leaf spring assembly includes a leaf spring having an eye positioned at a free end, the eye configured to hold a bushing. The bushing having a first component connected to a second component. The first component having a first outer metal portion, a first inner metal portion and a first rubber portion concentrically arranged around each other, the first rubber portion spacing apart the first outer metal portion from the first inner metal portion. At least one of the first outer metal portion, the first inner metal portion and the first rubber portion having a first tapered end. The second component having a second outer metal portion, a second inner metal portion and a second rubber portion concentrically arranged around each other, the second rubber portion spacing apart the second outer metal portion from the second inner metal portion. At least one of the second outer metal portion, the second inner metal portion and the second rubber portion having a second tapered end. A fastener is provided configured to connect the first tapered end of the first component and the second tapered end of the second component, the first component and the second component configured to at least partially overlap wherein the bushing assembly forms a bottleneck shaped center portion when fully assembled

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for a bushing for improved longitudinal rotational compliance, axial retention, and near rigid characteristics in all other directions. The bushing includes an outer metal portion, an inner metal portion, and a bonded rubber positioned between the inner metal portion and the outer metal portion. The inner and outer metal portions have bottleneck features adapted to overlap.

The assembly of the present invention provides for a multi assembly bushing having a bottleneck feature in the center of the bushing. The bushing100includes outer metal components102,104having outer surfaces106,108. The bushing assembly100further includes inner metal components120,121positioned to overlap with the outer metal components102,104. A molded rubber132is positioned between the inner metal components120,121and the outer metal components102,104. This assembly utilizes mechanical locking by overlapping the metal components102,104and120,121. Both the inner metal components120,121and the outer metal components102,104have a bottleneck feature110,112,130,131to create an overlap when the over molded inner metal120,121is pressed into the outer can of the leaf spring assembly, such as illustrated inFIG. 5A and 5B. A single bushing of the prior art is replaced by two bottleneck bushings100a,100bfacing opposite ways and occupying the same general space within the can of the leaf spring assembly. The leaf spring assembly200includes a main leaf spring portion along with the eye204of the leaf spring. The bushing100a,100bare inserted into the eye204and connected together at the inner portions of the bushings100a,100b. A fastener (or multiple fasteners)116are inserted into the center bore114of the bushing to secure the bushings. For either a positive or negative axial loading, the mechanical interlock from one of the halves retains the bushing assembly. This feature also allows for minimal compression of the rubber, thus increasing rotational compliance.

The inner metal components120,121are illustrated inFIGS. 6-9. The inner metal component120includes a center bore114extending through the entire length of the inner metal120. The inner metal120includes a first portion124and a bottlenecked portion112. The first portion124is larger in diameter as compared to the bottlenecked portion112. As illustrated inFIGS. 6 and 8, the bottlenecked portion is gradual thus changing the diameter from the first portion124to the bottlenecked portion112at an angle as illustrated by reference numeral140. In the final assembly, two inner metal portions120,121are provided.

The outer metal portions102,104are larger in diameter as compared to the inner metal120,121. The outer metal portion104includes a large center portion126adapted to receive the inner metal120,121. The center portion126is generally cylindrical having a smooth interior surface. The outer metal104includes an outer surface108(the outer metal portion102having an outer surface106) which is also generally smooth. A bottleneck feature130,131is illustrated as tapering down from the larger portion104ato lower diameter portion104b,which is the bottleneck feature. This taper is illustrated at reference numeral128.

In the present embodiment, the outer metal is SAE J1392 XLF340 steel, but could be any grade of stamping steel or aluminum. Further in this present embodiment, the inner metal is ASTM 1040 steel, but could be any material that meets the clamp load requirements and does not provide noticeable creep. Any of the rubber components of the present invention could be replaced with plastic, polymer, plastic-like or polymer-like materials. In the present embodiment, the bonded rubber has a durometer ranging from 40-80 ShoreA. In this specific bonder rubber component, the durometer ranger between 60-75 ShoreA.

Rubber is molded into a thin layer over and bonded to the inner metal120,121. The rubber132includes a plurality of ridges134adapted to press against the inner surface of the outer metal. In alternative embodiments, the rubber132is smooth or has various other different textures to accommodate the assembly. The molded assembly having the rubber132molded to the inner metal portion120is illustrated inFIGS. 12-16. This molded assembly as illustrated inFIGS. 12-16is press fit into the outer metal102,104as illustrated inFIGS. 10-11.

The final assembly as illustrated inFIGS. 17-20is pushed into an outer can of a leaf spring assembly, such as illustrated inFIG. 5. A mechanical overlap is created between the first bushing assembly portion (or component)102aand the second bushing assembly (or component)102b.A bolt116is inserted through the inner metals and tightened down with a fastener. A portion of the vehicle's weight is then distributed across the two bushings100a,100b.The bottleneck feature prevents the assemblies from dislodging themselves during axial loading and provides for improved performance characteristics as compared to the prior art.

It should be noted that the configuration discussed above may also be reversed. This configuration is illustrated inFIG. 1Bat the assembly101. The configuration of the assembly101connects the wider ends120,121instead of the tapered portions. The assembly can be applied to busing with through holes for bolts (such as shown inFIG. 1A) or bar pins which do not extend through the center of the part. Further, the assembly may connect without a fastener by means of overlapping, adhesives, welding or other known connection means.