Abstract:
An improved method of manufacture for an isolated cross-axis ball joint, utilized in an articulated torque-rod end, wherein an isolated outer cylindrical element is chemically mold bonded to a pre-curled intermediate sleeve to provide isolation there from. The inner bearing element is comprised of a heat-treated spherical inner sleeve that rotates upon two lubricated plastic bearing races and two seals with encapsulated steel washers in each seal. The intermediate sleeve is pre-curled or manufactured at one end so as to retain a first seal. The first bearing race is then dropped in, followed by the heat-treated spherical inner sleeve, followed by the second ball race and the second seal. The second end of the intermediate sleeve is then fixed by compression and implementation of a retaining means, such as curling to close the bearing element. The seals provide the wear compensation of the ball joint by adding compression after the fixing of the intermediate sleeve.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to the articulating device of a torque rod. More specifically, this invention relates to an improved articulated torque rod having a cross-axis ball joint with an elastomer retainer, and method of manufacturing the same.  
       BACKGROUND OF THE INVENTION  
       [0002]     Ball joints are often used in torque rods interposed between a wheel axle of a vehicle and a chassis thereof thereby to automatically adjust to the movement of the wheel axle relative to the chassis while the vehicle is running on rough or uneven roads. In the case of a torque rod, the ball is equipped with either a straddle mount or a taper pin which is attached to a spherical ball. The ball rotates within races, allowing the rod or assembly holding the ball races to rotate freely in three dimensions. A ball joint in a torque rod should be simple in its construction so as to be easily produced, and it should be smoothly operated and be capable of being used for a long period of time and further its life should be semipermanent.  
         [0003]     There are numerous prior art patents utilizing ball joints in torque rods for a variety of uses. U.S. Pat. No. 3,451,700 issued to F. R. Smith teaches of a ball joint having a rubber seal for preventing foreign matter from damaging the articulating element, but requires additional means employed to apply pressure to the ball races, which increases manufacturing costs and time. U.S. Pat. No. 5,902,050 Issued to Balczun, et al show a ball joint end of a rod utilizing an isolating elastomer to minimize the transmission of vibration, but requires bonding the elastomeric isolation element to at least one surface of the ball joint.  
         [0004]     The present invention provides for the manufacture of a superior isolated ball joint utilizing a simplified method of manufacturing and assembly, eliminating the need for bonding the isolating elastomer to the joint, and minimizing components, while still providing the desired isolation, ideal for use in articulated torque rods. Furthermore, the concepts covered herein utilize principles which easily apply to the manufacturing of isolated ball joints for use in bushings as well as torque rods.  
       SUMMARY OF THE INVENTION  
       [0005]     It is proposed herein that an object of the present invention is to provide a high articulation joint assembly.  
         [0006]     A further object of the present invention is to provide a ball joint race design that adapts to the ball and race wear, while maintaining nearly constant spring pressure.  
         [0007]     It is another object of the present invention to provide a dust boot, protecting the joint from the introduction of foreign matter, which is integral with the ball race spring.  
         [0008]     Another object of the present invention is to provide a high articulation ball joint that can provide rigid response in one design iteration.  
         [0009]     It is also an object of the present invention to provide a high articulation ball joint that further provides an elastomer isolator between the ball carrying device and the ball holding device.  
         [0010]     Another object of the present invention is to provide a high articulation device that could be mounted as a straddle, taper pin, or through-hole ball joint known in the art.  
         [0011]     It is another object of this invention to provide additional isolation of noise, vibration, and harshness between an axle and a frame by supplying the option of an articulation device isolated using a shock absorbent elastomer.  
         [0012]     Finally, it is object of the present invention to eliminate the need for additional components for retaining the seals and adding compression to the bearing element.  
         [0013]     The foregoing objects are achieved by a new method of manufacturing an improved articulated torque rod having a cross-axis ball joint with an elastomer retainer, and the resulting ball joint. In a first embodiment, the ball joint is located at the end of an articulating torque rod. Torque rods are generally manufactured from forged steel, cast iron, cast aluminum, or machined bar and tube, but could be manufactured from a variety of materials. Notwithstanding the manufacturing material, the torque rod end contains a cross-axial cylindrical hole with a lower restraining means either a disk, ring, snap ring or some other means such as forming a ledge from the bottom side of the torque rod cylinder wall. A lower ball race, manufactured from a synthetic material, preferably acetyl is then dropped in the cylindrical hole. The spherical ball component is then placed on the lower ball race, wherein an upper ball race is placed on top of the ball component.  
         [0014]     The elastomer spring is then placed on top of the second ball race, wherein the elastomer spring and dust boot are molded in one continuous shape. It is additionally preferred in this embodiment that a steel retaining ring is molded into the elastomer spring. However, neither approach is essential to the invention. All three components could be independent.  
         [0015]     Once the elastomer spring and retaining ring is in place, the entire assembly is fixed by adding another restraining device such as a snap ring, rolled edge, or formed metal edge. These restraining devices are put in place while the elastomer spring is under compression. When the assembly is released from the restraining fixture, the elastomer spring maintains the ball races to the ball under a predetermined, and measurable load.  
         [0016]     In an alternative embodiment, the ball joint is modular for use as the inner component of an elastomer bushing. In this case, the ball joint is assembled as above, however in place of snap rings, alternatively, the assembly is contained within a thin-walled, intermediate cylinder. The cylinder ends are curled inward around the steel retaining rings, containing the articulating inner member and races. The cylinder can then be inserted into a torque rod end, along with an isolating rubber insert. The insert serves as a shock isolation device, and allows additional articulation of the inner metal if necessary.  
         [0017]     Further 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 intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0019]      FIG. 1  is a partial perspective view of the articulating end of a torque rod end having a through-hole ball joint assembled consistent with the present invention contained there within;  
         [0020]      FIG. 2  is a partial cross sectional side view of the articulated torque rod end of  FIG. 1 ;  
         [0021]      FIG. 3  is a partial cross sectional side view of an articulated torque rod end, having a taper-pin ball joint assembled consistent with the present invention contained therewith;  
         [0022]      FIG. 4  is a cross sectional side view of the elastomer spring and incorporated dust boot of the articulated torque rod end of  FIG. 3 ;  
         [0023]      FIG. 5  is a cross sectional side view of a modular ball joint assembly comprising a second embodiment of the present invention, having a through-hole ball joint assembled consistent with the present invention contained there within;  
         [0024]      FIG. 6  is a cross sectional side view of the intermediate and outer sleeves of the modular ball joint assembly of  FIG. 5 , prior to introduction and assembly with the ball joint; and  
         [0025]      FIG. 7  is a cross sectional side view of the elastomer spring and incorporated dust boot of the modular ball joint assembly of  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0027]     Referring initially to  FIGS. 1 and 2 , an articulated torque rod end having a through-hole ball joint  100  assembled consistent with the preferred embodiment of the present invention contained there within is shown. The ball joint  100  is located at the end  130  of an articulating torque rod  132 , often used in automotive suspension systems. The torque rod end  130  is generally manufactured from forged steel, cast iron, cast aluminum, or machined bar and tube, but could be manufactured from a variety of materials. Regardless of the material, the torque rod end or housing  130  contains a cross-cylindrical bore  134  through which the ball joint  100  is locate.  
         [0028]     In assembling the ball joint  100  into the torque rod end  130 , a rigid, lower restraining means  144  comprising either a disk, ring, or snap ring is received in an annular grove  138  located at one end of the inner cylindrical bore  134  of the torque rod end  130 . A first spring seal  150  is placed within the cylindrical bore  134  to rest upon the lower restraining means  144 . The spring seal  150  comprises an elastomer ring with an encapsulated steel washer  156  attached thereto, and further embodies a convoluted dust shield  154  with an aperture there through, for snugly receiving and sealing the lower extension of a ball pin member  120  having a through bore  124 , while allowing for the articulation of the ball joint. This spring seal  150  provides protection to the upper and lower ball races  146 ,  148  from foreign matter which would ordinarily cause premature wear or failure. The first ball race  148 , manufactured from a synthetic material, preferably acetyl but not limited to such is then dropped in the cylindrical aperture, to rest upon the first spring seal  150 .  
         [0029]     The ball pin member  120 , having spherical ball component  126  is manufactured of heat treated metal, or may embody a plastic over-molded sleeve not shown, for providing a plastic on plastic bearing joint. The ball component  126  is placed on the cradling first spherical ball race  148  so that the lower extension of the ball pin member  120  travels through the aperture in the first spring seal  150 . An upper spherical ball race  146  is subsequently placed on top of the spherical ball component  126  of the ball pin member  120 .  
         [0030]     A second, identical elastomer spring seal  150  is installed, also having an upper, encapsulated steel washer  152  and molded convoluted dust shield  154  with an upper sealing aperture for snugly receiving and sealing the upper extension of a ball pin member  120 , shown having through bore  122 . This second spring seal  150  is placed over the upper extension of the ball pin member  120  and rests upon the second ball race  146  within the cylindrical bore  134 . Once the second elastomer spring seal  150  is in place, the entire assembly is fixed by adding an upper restraining means  142  received within an upper annular groove  136  while the elastomer spring seal  150  is under compression. Once assembled, the elastomer spring seal  150  maintains the ball races  146 ,  148  to the spherical ball component  126  under high axial, or conical loads.  
         [0031]     Referring now to  FIGS. 3 and 4 , a variation in the above embodiment is shown. In particular, an articulated torque rod end or housing  132 ′, utilizing a tapered ball pin member  160  which extends axially out of one end of the torque rod cylindrical bore  134 ′, having a threaded end and a tapered ball end for attachment to a generally spherical, inner ball member  164 , through complimentary threaded attachment means  162  and  166 . Additional methods of attachment including welding, forming, or crimping may be employed, as well as manufacturing the ball pin member  160  and inner ball member  164  as a single element which is known in the art and also intended to be compatible with the scope of this invention.  
         [0032]     Assembly follows the above detailed description with a few exceptions. A rigid, upper restraining means  142 ′ comprising either a disk, ring, or snap ring is received in an annular grove  136 ′ located at one end of the inner cylindrical bore  134 ′ of the torque rod  132 ′. A retaining cap  140  is placed within the cylindrical bore  134 ′ to rest upon the upper restraining means  142 ′. The retaining cap  140  acts as a sealing member, keeping foreign material out of the ball joint, as well as providing a support means for supporting the ball joint once assembled under compression.  
         [0033]     A spacer  170  and upper ball race  146 ′ is then placed in the cylindrical bore  134 ′, to rest upon the retaining cap  140 . The ball pin member  160  having spherical inner ball member  164  is then placed within the bore  134 ′, cradled by the spherical ball race  146 ′. A lower spherical ball race  148 ′ is placed over the opposite side of the spherical inner ball member  164  on the ball pin member  160 .  
         [0034]     The elastomer spring seal  150 ′ shown enlarged in  FIG. 4  for clarification, is installed over the lower ball race  148 ′ and embodies an encapsulated steel washer  152 ′ and convoluted dust shield  154  having a lower sealing aperture  151  for snugly receiving and sealing the extension of a ball pin member  160 , while still allowing for the articulation of the ball joint. The spring seal  150 ′ is placed over the extension of the ball pin member  160 , so that surface  155  comes to rest upon the lower axial surface of the lower ball race  148 ′ within the cylindrical bore  134 ′. Once the elastomer spring seal  150 ′ is in place, the entire assembly is fixed by adding a lower restraining means  144 ′ received within an lower annular groove  138 ′while the elastomer spring seal  150  is under compression. Once fixed, the elastomer spring seal  150  maintains the ball races  146 ,  148  to the spherical ball component  126  under high axial, or conical loads.  
         [0035]     Referring now to  FIGS. 5-7 , an alternative embodiment of the present invention is shown, wherein the ball joint  200  is modular, comprising the inner component of an elastomer bushing. In this embodiment, the ball joint  200  is assembled as above, however in place of snap rings or other restraining means  144 ′  142 ′, the assembly is contained within a thin walled housing or intermediate cylinder  260 .  
         [0036]     Particularly, the assembly of this embodiment consists of an isolated outer cylindrical sleeve  230 , which may have one or more flanged ends  231  for retainment within a bushing or other application. The intermediate cylinder  260  is chemically mold-bonded coaxially within the inner bore  233  of the outer cylindrical sleeve  230  embodying resilient bushing  232 . The insert serves as a vibrational shock isolation device, and allows additional articulation of the inner metal if necessary.  
         [0037]     The intermediate cylinder  260  is pre-curled inward radially at one end  261  prior to molding, forming a radially inward flange  265  wherein a first spring seal  250  is placed within the cylindrical bore  264  to rest upon the flange  265 . The spring seal  250  comprises an elastomer ring with an encapsulated steel washer  252  molded there within but not bonded to the spring seal  250 , and further comprises a convoluted dust shield  254  end with an aperture  251  there through which snugly receives and seals the extension of a ball pin member  220  shown with through bore  222 , wherein the dust shield  254  protects the first and second ball races  246  and  248  from foreign matter which would ordinarily cause premature wear or failure, while still allowing for articulation of the ball joint. The first ball race  246 , also preferably manufactured from a synthetic material such as acetyl but not limited to such, is then dropped in the cylindrical aperture, to rest upon the first spring seal  250 .  
         [0038]     The ball pin member  220 , having spherical ball component  226 , is manufactured of heat treated metal, and optionally has a plastic over-molded sleeve not illustrated, for making a plastic on plastic bearing joint. The ball component  226  is placed on the cradling first spherical ball race  246  so that the extension of the ball pin member  220  travels through the aperture in the first spring seal  250 . The second spherical ball race  248  is subsequently placed on top of the opposite side of the spherical ball component  226  on the ball pin member  220 .  
         [0039]     A second, identical elastomer spring seal  250  is installed, also having an encapsulated steel washer  256  and molded convoluted dust shield  254  with aperture  251  for snugly receiving and sealing a second extension of a ball pin member  220 . This second spring seal  250  is placed over the upper extension of the ball pin member  220  and rests upon the second ball race  248  within the cylindrical bore  264 . Once the second elastomer spring seal  250  is in place, the entire assembly is fixed by curling the second end  266  of the intermediate cylinder  260  inward, radially while simultaneously compressing the second elastomer spring seal  250  inward against the outer wall of the of the intermediate cylinder  260  forming flange  262 , at the second end  266  of the intermediate cylinder  260 . Once fixed, the elastomer spring seal  250  maintains the ball races  246 ,  248  to the spherical ball component  226  under high axial, or conical loads, while providing an articulating, isolated cross-axis ball joint. Additionally, any of the methods of seal retaining means described in the first embodiment above are intended to be applicable to this second embodiment including, though not limited to the use of snap rings, rolling or forming the edges of the intermediate cylinder  260 .  
         [0040]     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.