Patent Application
20080164645
The present invention relates to articulating bushings. More specifically, this invention relates to the manufacturing of bushings having an increased axial rate and durability for use in torque rods, leaf springs, independent control arms, and the like.
Applications for a cartridge-style bushing include, but are not limited to, torque rods, leaf springs, independent suspension control arms, and other suspension control rods. These and other applications are used on a wide variety of vehicles such as trucks, buses, off-highway vehicles, rail cars, and other automotive applications.
Current bushing designs utilize either a curled outer tube or washers (bonded or non-bonded) to add confinement to the rubber, which improves durability as well as increases the axial rate of the bushing. One such example is shown in U.S. Pat. No. 6,845,995 issued to Cai et al. This prior art design teaches of a suspension-bar assembly for an automotive vehicle including a suspension bar having a bushing; a bushing retainer that exerts radially and axially compressive forces onto the bushing such that the bushing is in frictional engagement with the suspension bar, thereby preventing relative movement of the bushing and the suspension bar; and a mounting bracket that is adapted to connect the suspension bar to the automotive vehicle.
As known in the art, rubber works best in compression; therefore, by adding features such as washers, curling the outer tube, or ball shaping the profile of the inner meal, higher load capacities can be achieved as well as improved life expectancy of the bushing.
An alternative method is to swage or to compress the diameter of the bushing along the entire length of the outer tube, which improves durability and increases radial load-carrying capacity, but does not give high axial rates which are often desired in such applications. One such example is shown in U.S. Pat. No. 5,290,018 issued to Wantanabe et al. This patent teaches of a cylindrical damping bushing for securing a rod-shaped vibrating body to a base. The bushing includes a cylindrical vibration-damping rubber body having an inner bore through which the vibrating body is inserted. An upper side surface thereof comes into contact with the base while the remaining outer side surface thereof is retained by a bracket which is secured to the base.
These and other existing bushings often use expensive washers that are bonded to the elastomer, ball-shaped inner metals, and retaining rings to achieve high axial rates. The addition of washers or ball-shaped inner metals increases the cost of the bushing as well as makes the assembly more complex to manufacture. Swaging along the entire length does not give the additional axial rate desired. Furthermore, the curling feature alone does not provide high enough axial rates or axial load-carrying capacity for certain applications, such as an independent suspension.
The disadvantages in the prior art are overcome by the present invention providing for the increased axial rate of the bushing by approximately 130% over the same bushing without the swaged feature.
It is proposed herein that an object of the present invention is to provide a bushing having a high axial rate from 8,100 lbs./in. up to 18,600 lbs./in. and having increased durability for use in a wide variety of applications.
A further object of the present invention is to provide an elastomer bushing which is economical to manufacture and less complex to assemble than the prior art.
These and other advantages will become apparent in the present invention describing an elastomer bushing having a high fatigue life due to the compression and confinement of the rubber. The manufacture of the elastomer journal is conventional for commercial vehicle applications. In a primary embodiment, the rubber is bonded to a bar pin by an adhesive, wherein the rubber journal is then subsequently assembled into an outer tube. After assembly, the outer tube is curled to retain the rubber journal, and the center of the outer tube diameter is swaged or compressed so as to deform the outer tube into the rubber. The compressed groove in the outer tube comprises the unique feature of this bushing design. This groove provides a mechanical “footing” that resists movement when an axial load is applied.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Referring initially to
An outer tube 20 is subsequently placed over the rubber/elastomer element 18 which may also optionally be affixed to the rubber/elastomer element 18 by means of adhesive. The outer tube 20 is then subsequently curled inward around the rubber/elastomer element 18 at the distal ends of the tube to improve the durability of the bushing as well as maintain the position of the rubber/elastomer element 18.
The center of the outer tube 20 is then swaged 22 around the outer diameter so as to indent into the rubber/elastomer element 18.
Referring now to
Referring now to
As disclosed, the component can be manufactured with relative ease. After curling the ends of the outer metal tube of the bushing assembly, the center of the bushing can be swaged at the same manufacturing station. There are no additional components needed, and axial rate is increased as well as durability over bushings lacking these features.
In further alternative embodiments intended to be within the scope of the present invention, in place of swaging the outer diameter of the outer tube, the inner diameter could be machined to have a central rib, giving the same effect as the deformation of the outer tube. In some cases where a very high axial rate is needed and cost is not as significant as performance, the swage feature could be incorporated into a bushing that utilizes washers and a ball-style inner metal wall, as well. This invention could optionally further incorporate alternative rubber journal shapes with a groove in the center of the elastomer surface, which would further enhance the axial rate.
It is of further importance that the description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
