Abstract:
An improved universal joint device for socket wrenches. The improved device is constructed with exposed friction bearing surface portions on the handle and socket portions of the device for receiving the ends of a coil spring which maintains the universal joint in alignment during both tension and compression. The friction bearing surface portions are preferably knurled teeth positioned on the periphery of the handle and socket sections. The device is otherwise free of grooves or apertures for mounting the spring to the handle and socket portions.

Description:
TECHNICAL FIELD 
     The present invention relates to a spring loaded tool device. This invention more particularly pertains to a spring-loaded, variable tension, self-aligning universal joint adapter system for socket wrenches. 
     BACKGROUND OF THE INVENTION 
     The tool-making industry manufactures a myriad of adapters for its tools. One known type of adapter is a universal joint adapter for use with socket wrenches. This known universal adapter typically includes: a handle portion and a socket portion. Each end portion includes a bifurcated or forked end yoke member with a pair of arms. A swivel block pivotally connects the handle and socket portions via each pair of arms. A spring surrounds the swivel block and the handle and socket portions. The spring encircling the end portions and swivel block permits a user to hold a socket wrench in alignment with a nut or bolt, for example, without having to re-apply the wrench to the object several times. Without the spring, the end portions of the universal joint would not be able to maintain a desired angle or be maintained in concentric alignment. 
     There are a number of known methods for coupling the ends of the spring to the end portions of the device. One known method is to provide an aperture in each end portion for receiving and securing an end of the spring. In this embodiment, each end of the spring is configured to define a projection which extends radially inward. The radially extending ends are sized and configured to be retained in the aperture of each end portion. In other words, each end of the spring terminates in the aperture in the end portions. In this embodiment, the interconnection of the spring and the end portion is difficult to terminate because the radially extending ends typically have to be pried out of the apertures to remove the spring from encircling the end members and the swivel block. 
     However, a spring coupled in this manner is not capable of providing simultaneous exertion of compression and tension forces on opposing sides of the handle and socket portions because the spring is only mounted at one point along the circumference of each end portion. A single point of contact can not simultaneously exert opposing compression and tension forces on opposite end portions. Accordingly, this method requires a spring having a substantially greater wire diameter (making the spring substantially stiffer) in order that the forces exerted by the spring at each single point of contact do not bias the device in a non-axially aligned manner. Such stiff springs are detrimental to the goal of flexibility of the device. 
     In a second embodiment for coupling the spring to the handle and socket portions, the spring is mounted in annular groves positioned in both the handle portion and the socket portion. This manner of coupling the spring to the handle and socket portions is disclosed in my U.S. Pat. No. 5,458,028, entitled “SOCKET WRENCH DEVICE”, the entire disclosure of which is incorporated herein by reference. This patent discloses annular groves in the end portions having outer and inner lips or shoulders which define the inner and outer boundaries of the grooves within the socket and handle portions, respectively. By mounting the spring in this manner, the end portions are coaxially aligned in both tension and compression. However, machining such annular groves adds significant expense in manufacture, and these annular grooves do not permit the spring to be removed from the handle and socket portions in an easy manner. The difficulty in removing the spring can be remedied by double voids in the inner lip of a groove at one end of the device, as disclosed in my earlier patent. The purpose of the voids is to create a gap between the spring and the underlying lip or grove to facilitate removal and replacement of the spring. These voids may be obtained by machining away a portion of the outer surface of the lip. However, because of the orientation of the device as well as the location of the lip, machining the outer surface of the lip or groove is often a difficult machining operation, adding further manufacturing cost. 
     In response to the realized inadequacies of these known socket wrench devices, it became clear there is a need in the art for an easier and more economical manner of coupling the spring to the socket and handle portions of the device. This new socket wrench device must be capable of imparting both compression and tension forces to each yoke simultaneously and without slippage. Moreover, this new socket wrench device must permit the spring to be removed and replaced in an easy and economical manner. 
     SUMMARY OF THE INVENTION 
     The present invention solves the above-identified problems by providing an improved socket wrench device. The present invention seeks to provide an efficient method of mounting a coil spring to portions to a universal joint, while satisfying the need for imparting both compression and tension forces to each yoke simultaneously, which permits an advantageous reduction in spring strength and stiffness. Moreover, this new socket wrench device must permit the spring to be removed and replaced in an easy and economical manner. 
     Generally described, the present invention includes a universal joint having a handle portion and a socket portion. A swivel block is pivotally connected to both the handle and socket portions. The invention further includes a concentric aligning spring encircling the handle and socket portions and the swivel block for providing self-aligning forces. 
     The ends of the spring are coupled to the handle and socket portions by providing an exposed frictional surface portion at least partially around the circumference of each of the handle and socket portions. When the spring is mounted on the handle and socket portions, the frictional surface portions contact the inner diameter of each end of the spring. The handle and socket portions are otherwise free of grooves, holes or other recessed means for retaining the ends of the spring. 
     In accordance with one embodiment of the present invention, the exposed frictional surface portion is an annular knurled portion on both the handle and socket portions. Each knurled portion underlies one of the ends of the spring such that the knurled portions grip the inner diameter of the ends of the spring. By interconnecting the handle and socket portions of the device with the ends of the springs in such a manner, the spring of the socket wrench device is able to hold the handle and socket portions in alignment during both compression and tension, while also allowing the spring to be easily removed and replaced when the device is no longer in use, or when other performance characteristics are desired. 
     The foregoing has outlined rather broadly, the more pertinent and important features of the present invention. The detailed description of the invention that follows is offered so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter. These form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the disclosed specific embodiment may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of the socket wrench device of the present invention. 
     FIGS. 2A and 2B are partial side elevation views of different embodiments of the socket wrench device illustrating an enlarged view of the handle portion. 
     FIGS. 3A and 3B are side elevation views of the present invention illustrating variable force vectors created by the coil spring when the universal joint of the device is in an axially aligned position or pivoted into an axially deflected position, respectively. 
     FIG. 4A illustrates the device in axial alignment with normal spring compression C 1 . 
     FIG. 4B illustrates the device having axial deflection with increased spring compression C 2  and spring tension T. 
     FIGS. 5A and 5B illustrate the location of the memory position while the device is pivoted between the axially aligned position and the axially deflected position. 
    
    
     Similar reference characters refer to similar parts throughout several views of the drawings. 
     DETAILED DESCRIPTION 
     Referring now to the drawing in which like numerals indicate like elements throughout the several views, FIG. 1 illustrates an exemplary embodiment of a socket wrench device  10 . Generally described, the socket wrench device  10  includes a universal joint having a handle portion  12  and a socket portion  14 . Both the handle portion  12  and the socket portion  14  includes a bifurcated or forked end yoke member  16 . Each end yoke member  16  includes a pair of arms  18  having a bore hole  20  therethrough. 
     The socket wrench device  10  of the present invention further includes a swivel block  22  with a pair of axially perpendicular holes  24  and  26 . The swivel block  22  is inserted between both pairs of arms  18  of the forked members  16  to pivotally connect the handle and socket portions  12 ,  14  together. The swivel block  22  is maintained between the handle and socket portions  12 ,  14  by pins  28  which are press fitted through the bore holes  20  and the corresponding axially perpendicular holes  24 ,  26 . 
     A coil spring  30  surrounds the swivel block  22  and is mounted to the handle and socket portions  12 ,  14  by contacting exposed friction bearing surface portions on both portions  12 ,  14  such that the device  10  can hold the spring  30  in place during both tension and compression. FIGS. 2A and 2B best illustrate exposed friction bearing surface portions on the handle portion  12 . The friction bearing surface portion is machined into the surface of the handle and socket portions in a manner similar to that utilized for placing knurled teeth on the handles of tools to provide a grip. Because the present invention does not require annular grooves in the handle and socket portions, less material is required to manufacture the handle and socket portions resulting in the handle and socket portions having a smaller outer diameter. Consequently, the socket wrench device  10  may be made smaller. Also, no additional material is added to create the knurled teeth during the machining process. However, those skilled in the art understand that a variety of methods may be used to create a raised surface upon the periphery of an object to create a friction bearing surface. 
     FIG. 2A illustrates a partial elevation view of the handle portion  12  having an annular friction bearing surface portion  32 . In this embodiment, the friction bearing surface portion  32  is a plurality of knurled teeth  34  on the surface of the handle portion  12 . The knurled teeth  34  encircle the entire 360 degree periphery of the handle portion  12 , so that when the end of the spring  30  is placed on to the handle portion  12 , the end of the spring comes into contact with the knurled teeth  34 . Typically, the spring  30  is installed by hand by threading the spring  30  against the handle and socket portions  12 ,  14  until the ends of the spring are positioned in the desired location upon the knurled teeth  34  of the friction bearing surface  32 . 
     Each end of the spring  30  is able to remain in contact with the knurled teeth  34  because the knurled teeth  34  have a slightly increased outer diameter on the handle portion  12 . In FIGS. 2A and 2B, the outer diameter of the portion of the handle portion without the knurled teeth is shown generally by reference letter D, and the outer diameter of the portion of the handle portion with the friction bearing surface  32  is shown generally by the reference letter d. For example, when utilizing a ¾″×2{fraction (11/16)}″ steel universal joint from Boston Gear Works, North Quincy, Mass., the outer diameter of the portions without teeth is approximately 0.750 inches and the outer diameter of the friction bearing surface portions of knurled teeth is approximately 0.764 inches. Also, when utilizing a standard ⅜″ Cleveland type U-joint, the outer diameter is approximately 0.738 inches without the knurled teeth and the outer diameter with the knurled teeth is approximately 0.752 inches. 
     It is possible to create a broad range of friction bearing surface portions from a very fine grip having a large number of teeth per inch to a coarse grip having a small number of teeth per inch. Generally, the number of knurled teeth per inch should range from 10 to 80 knurled teeth per inch. Preferably, the friction bearing surface portion should include 16 knurled teeth per inch of surface which is usually sufficient to retain the spring on the handle and socket portions  12 ,  14 . Although the exposed friction bearing surface is described in FIGS. 2A and 2B as existing on the handle portion  12 , exposed friction bearing surfaces also exist upon the socket portion  14  as shown in the other Figures. 
     FIG. 2B illustrates an alternative embodiment of the exposed friction bearing surface portion. In FIG. 2B, the handle portion  12  includes an annular array of friction bearing surface segments  36  positioned equidistant apart from one another. Each friction bearing surface segment  36  includes a plurality of knurled teeth  34 . An important aspect of the embodiment shown in FIG. 2B is that each segment  36  of knurled teeth  34  is placed an equal distant apart so that the spring  30  may be retained on the handle portion  12  and the socket portion  14  in a manner that is capable of imparting both compression and tension forces to each yoke member  16  simultaneously. Although the exposed friction bearing surface portions  32 ,  36  of the present invention is described as having knurled teeth  34 , alternative embodiments of the exposed friction bearing surface portion of the present invention can exist that utilizes an exposed finish on a portion of the surface of an object to generate increased friction between parts in contact with one another such that the parts may not be separated from one another without requiring additional force. 
     FIGS. 3A and 3B illustrate variable force vectors  40  created by the coil spring  30  when the universal joint of the device  10  is in an axially aligned position or pivoted into an axially deflected position, respectively. As best shown in FIG. 3A, the compression and tension forces shown by vectors  40  are applied from the spring  30  to the yoke  16  about the 360 degree periphery of the socket portion  14 . FIG. 3B then depicts the opposing compression and tension forces shown by vectors  40  upon the yoke  16  of the socket portion  14  when the device  10  is oriented into the axially deflected position. The device  10  has a normal spring compression while in the axially aligned position. FIG. 4A illustrates the device  10  in the axially aligned position with a normal spring compression C 1 . In FIG. 4B, however, the device  10  in the axially deflected position has an increased spring compression C 2  and spring tension T. Finally, FIGS. 5A and 5B illustrate the location of the memory position of the spring  30 , identified by reference number  50 ,  30  while the device  10  is pivoted between the axially aligned position and the axially deflected position, respectively. During axial deflection, the forces acting at the end coil of spring  30  to return to the memory position  50  are identified by reference numbers  52  and  54 . FIGS. 3B,  4 B and  5 B illustrate that the device  10  with exposed friction bearing surface portions  32 ,  36  has the ability to impart both compression and tension forces to each yoke simultaneously. 
     The present invention has been described in relation to particular embodiments which are intended in all respects to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is described by the appended claims and supported by the foregoing description.