Abstract:
A sealing cover assembly for an articulating joint. The articulating joint includes a first rotational member and a second rotational member. The sealing cover assembly includes a first portion having a plurality of fastening portions. The fastening portions are coupled to the second rotational member for rotation therewith. The sealing cover assembly also includes a second portion adapted for connecting to the driveline and a plurality of damping members constructed of at least a first material and interconnecting the first portion to the second portion.

Description:
TECHNICAL FIELD 
     The present disclosure relates to torsional damping and in particular to a constant velocity joint (CVJ) sealing cover assembly including, a torsional damper. 
     BACKGROUND 
     Universal joints, and especially constant velocity joints, operate to transmit torque between two rotational members. The rotational members are typically interconnected by a cage, or yoke, that allows the rotational members to operate with their respective axes at a relative angle. Constant velocity joints and similar rotating couplings typically include a boot cover assembly and grease cover to enclose and protect the coupling during operation. Since the boot cover assembly is partially flexible, the boot cover assembly is able to seal around the joint while permitting articulation and relative axial movement of differing rotating members of the joint. The boot cover assembly and the grease cover seal lubricant in the joint so as to reduce friction and extend the life of the joint. The boot cover assembly and the grease cover also seal out dirt, water and other contaminants to protect the functionality of the joint. However, leaks may reduce the life of the joint, and contaminants in the grease may disturb the chemical composition of the grease, degrading its performance. 
     Universal joints are commonly classified by their operating characteristics. One important operating characteristic relates to the relative angular velocities of the two shafts connected thereby. In a constant velocity type of universal joint, the instantaneous angular velocities of the two shafts are always equal, regardless of the relative angular orientation between the two shafts. In a non-constant velocity type of universal joint, the instantaneous angular velocities of the two shafts vary with the angular orientation (although the average angular velocities for a complete rotation are equal as one shaft accelerates and decelerates relative to the rotational speed of the other shaft, creating a rotational speed oscillation). Another important operating characteristic of a joint may be the ability of the joint to allow relative axial movement between the two shafts. A fixed joint does not allow this relative movement, while a plunge joint does. 
       FIG. 1  illustrates an exemplary the CVJ  20 . The CVJ  20  includes driven end  22  and a driving end  24 . The CVJ  20  further includes a joint assembly  26  coupled to a shaft  28  with a boot cover assembly  30  connected therebetween. The CVJ  20  further includes a grease cover  32  that seals the driven end  22 . The boot cover assembly  30  includes a metal cover  34  and a flexible boot  40 . A portion of the metal cover  34  is crimped onto the boot  40  for attachment thereto. The boot cover assembly  30  protects the moving parts of the CVJ  20  during operation. The joint assembly  26  includes a first rotational member  42 , a second rotational member  44 , and a plurality of balls  46  retained in a race  48 . The shaft  28  is splined to the second rotational member  44  to allow axial movement therebetween. 
     When the instantaneous angular velocities of two portions of a driveline are not equal, the differences in velocities will impart a torsional oscillation into the driveline. That is, for example, since the instantaneous rotational velocity of at least the balls  46  and the race  48  are different than the instantaneous rotational velocity of the first rotational member  42  and the second rotational member  44  when the joint  20  is operating at an angle (the first rotational member  42  and the second rotational member  44  are not coaxial), torque and rotational velocity that is transmitted from the first rotational member  42  to the second rotational member  44  will include an oscillatory magnitude imparted by a fraction of the rotational inertia of the balls  46  and the race  48 . A rotational speed or torque with an oscillatory magnitude may undesirably drive other vibrations within a drive train or a vehicle, or may reduce the useful life of drivetrain components. 
     Other contributors of oscillatory magnitude of rotational speed and torque within a drivetrain include the combustion events in an internal combustion engine, gear backlash, and the magnetic field pull and push between the magnet and the armature of an electric motor. While a large portion of the magnitude of these oscillations may be dampened by the torsional deflection of torque transmitting shafts and torsional dampers, such as those found in clutch disks, some oscillatory magnitude will typically transmit through the driveline. Additionally, shorter shafts may result in less ‘absorption’ of rotational speed and torque oscillations, resulting in a greater magnitude of transmitted oscillations. 
     What is needed, therefore, is an apparatus and method of reducing or eliminating the oscillatory magnitude of rotational speed and torque within a drivetrain. 
     SUMMARY 
     An embodiment includes a sealing cover assembly for an articulating joint. The articulating joint includes a first rotational member and a second rotational member. The sealing cover assembly includes a first portion having a plurality of fastening portions. The fastening portions are coupled to the second rotational member for rotation therewith. The sealing cover assembly also includes a second portion adapted for connecting to the driveline and a plurality of damping members constructed of at least a first material and interconnecting the first portion to the second portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the drawings, preferred illustrative embodiments are shown in detail. Although the drawings represent some embodiments, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present invention. Further, the embodiments set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description: 
         FIG. 1  is a sectional view of a constant velocity joint. 
         FIG. 2  is a sectional view of a joint assembly in accordance with an embodiment. 
         FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 2 , with some components visible through a cover plate for clarity. 
         FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 3 , with some items removed for clarity. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2  illustrates a constant velocity joint  120  having a driven end  122  and a driving end  124 . Joint  120  further includes a joint assembly  126  that is coupled to a shaft  128 . A boot cover assembly  130  is connected between the joint assembly  126  and the shaft  128 . A sealing cover assembly  132  seals the driven end  122  of joint  120 . Joint assembly  126  includes a first rotational member  142 , a second rotational member  144 , and a plurality of balls  146  retained in a race  148 . As illustrated, shaft  128  is splined to second rotational member  144  and the second rotational member  144  is positioned coaxial with the first rotational member  142 . 
     As illustrated in  FIG. 2 , the sealing cover assembly  132  interconnects the joint  120  with a driveshaft  150 . The driveshaft  150  includes a shaft portion  152  and a flange portion  154  having a plurality of second portion coupling apertures  156 . In the embodiment illustrated, the flange portion  154  is generally triangular shaped and centered on the shaft portion  152 . 
     The joint assembly  126  can be any type of articulated universal joint, including a plunging tripod, a fixed tripod, a plunging ball joint, and a fixed ball joint. Typical joint assemblies are disclosed in commonly-owned U.S. Pat. Nos. 6,817,950, 6,776,720, 6,533,669 and 6,368,224, and 5,899,814, the disclosures of which are hereby incorporated by reference in their entireties. The driven end  122  may be welded or otherwise coupled to a driveshaft or other drivetrain component. 
     The sealing cover assembly  132  includes a first portion  160 , a second portion  162 , and a plurality of damping members  164 . The first portion  160  includes a generally circular sealing portion  170 , a generally cylindrical outer portion  172 , and a plurality of fastening portions  174 , and a cover plate  176 . The sealing portion  170  includes a sealing surface  180  ( FIG. 4 ), an opposing interior surface  182 , and a joint mating surface  184  with a plurality of joint mating surface apertures  186  formed therein. The sealing portion  170  may include a vent (not shown) as desired. 
     The cover plate  176  includes a cover plate interior surface  190 , a cover plate exterior surface  192 , and a plurality of cover plate apertures  194 . Each damping member  164  includes a body  200  having a first portion coupling portion  202  and a second portion coupling portion  204 . 
     The second portion  162  includes a plurality of elongated members  210  that extend through the second portion coupling apertures  156  to couple to the flange portion  154  of the drive shaft  150 . Each member  210  includes a damping member coupling portion  212  and a flange coupling portion  214 . 
     A fastener  220  ( FIG. 2 ), such as, for example, a bolt, may be interposed through each cover plate aperture  194 , a fastening portion  174 , a first portion coupling portion  202 , a joint mating surface aperture  186 , and into the first rotational member  142 . As at least one of the fasteners  220  is fastened, such as rotating a bolt as threads extending from the bolt engage a threaded surface formed on the interior of the first rotational member  142 , the first portion  160  is coupled to the first rotational member  142  of the joint  120 , the joint mating surface  184  of the sealing portion  170  is coupled to first rotational member  142 , sealing the lubricant within the joint  120 , and the fastening portion  174  of the first portion  160  is coupled to at least one of the damping members  164 . 
     In the embodiment illustrated, the fastening portions  174  are tubular metal bushings that extend from the sealing portion  170  and the first rotational member  142  to the cover plate  176 , and the first portion  160  and the second portion  162  are 8-gauge sheet metal, although other suitable thicknesses and materials may be used. Additionally, while the cover plate  176  is illustrated in a triangular shape in  FIG. 3 , the cover plate  176  may be generally circular with arcuate slots (not shown) for the second portions  162  to extend therethrough to better seal the interior of the sealing cover assembly  132  and the damping members  164  from the operating environment of the joint  120 . 
     Also in the embodiment illustrated, the sealing cover assembly  132  includes three damping members  164 . although any suitable number of damping members may be used. Specifically, a single annular damping member having appropriately spaced apertures for the second portions  162  and the fastening members  174  may be used. 
     The damping members  164  selectively dampen torsional oscillations within the drive train as the joint  120  rotates due to the energy absorbing properties of the material of construction of the damping members  164 . In the embodiment illustrated, the damping members  164  are constructed of a first material that is preferably a flexible material with suitable damping qualities, and may be plastic or any polymer or elastomer, such as rubber, silicone, or thermoplastic elastomer (TPE). 
     An embodiment of a method of torsionally damping a driveline with the joint  120  is as follows. During operation torque is transferred between the driveshaft  150  and the shaft  128  through the damping members  164 . When the rotational speed of one of the driveshaft  150  and the shaft  128  includes an oscillatory magnitude, the increase and decrease in rotational speed of one of the driveshaft  150  and the shaft  128  will urge the other of the driveshaft  150  and the shaft  128  to rotate with a similar oscillatory magnitude. However, as the increase in rotational speed is transmitted through the damping members  164  the damping members  164  will absorb, or store, energy, and as the decrease in rotational speed transmits through the damping members  164  the damping members  164  will release the stored energy, resulting in a rotational speed with a lower oscillatory magnitude. 
     Thus assembled and operated, the plurality of damping, members  164  interconnect the first portion  160  with the second portion  162  as the sealing, cover assembly  132  provides a rotational damper for the driveline containing the joint  120 . 
     The damping members  164  may include wires or other second materials within the body  200  to stiffen the body  200  and permit the body  200  to store a greater amount of energy than if the body were constructed of only the first material. The second material is preferably a metal and/or a metal alloy and may be encircled around the damping, member coupling portion  212  and the fastening members  174  to provide additional resistance against the deformation of the body  200  as torque is applied thereto. 
     Although the steps of the method of constructing the joint  120  are listed in a preferred order, the steps may be performed in differing orders or combined such that one operation may perform multiple steps. Furthermore, a step or steps may be initiated before another step or steps are completed, or a step or steps may be initiated and completed after initiation and before completion of (during the performance of) other steps. 
     The preceding description has been presented only to illustrate and describe exemplary embodiments of the methods and systems of the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.