Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of application Ser. No. 09/877,717, filed Jun. 8, 2001, now U.S. Pat. No. 6,722,667 which claims the benefit under 35 U.S.C. §119(e) of Provisional Patent Application No. 60/210,631, filed Jun. 9, 2000, the disclosures of which are hereby expressly incorporated by reference. 

   FIELD OF THE INVENTION 
   The present invention relates generally to power tools and, more particularly, to a quick release connector for a handheld power tool. 
   BACKGROUND OF THE INVENTION 
   Typical handheld power tools, such as drills, include a chuck adapted to securely couple a cylindrical or hex shank of a workpiece, such as a drill bit. In the past, coupling the workpiece to the power tool was manually accomplished by inserting the workpiece into the chuck and using a chuck key to selectively lock the workpiece to the power tool. Developments in coupling the workpiece to the power tool have resulted in a locking mechanism that is actuatable between a locked and unlocked position with the use of a single hand. Such locking mechanisms lock the hex shank of the workpiece to one side of the connector opposite the locking mechanism in a pressing operation. Although such locking mechanisms are effective at coupling a workpiece to a power tool, they are not without their problems. 
   One such problem resulting from the existing locking mechanisms results from how the workpiece is locked to the power tool. In this regard, forcing the hex shank of the workpiece to one side of the connector&#39;s hex cavity tends to increase runout in the resulting hex shank/connector interface. 
   Another problem associated with existing locking mechanisms is that the spring mechanism in the connector keeps a substantially constant tension on the locking mechanism. This tension must be relieved to remove the hex shank from within the connector. As a result, simultaneously relieving the tension and removing the hex shank from the connector results in a connector that is difficult to operate with one hand. 
   Thus, there is a need for a connector for a power tool that is operable with one hand and reduces potential runout. 
   SUMMARY OF THE INVENTION 
   A connector formed in accordance with one embodiment of the present invention includes an assembly adapted to releasably receive an end of a workpiece. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a connector for a power tool formed in accordance with one embodiment of the present invention; 
       FIG. 2  is an exploded view of a connector for a power tool formed in accordance with one embodiment of the present invention; 
       FIG. 3  is a side exploded view of a connector for a power tool formed in accordance with one embodiment of the present invention; 
       FIG. 4  is a cross-sectional view of the connector of  FIG. 3  taken substantially through Section  4 — 4 ; 
       FIG. 5  is a perspective view of an alternate shaft for a connector formed in accordance with the present invention; 
       FIG. 6  is a side planar view of the alternate shaft of  FIG. 5 ; 
       FIG. 7  is an end planar view of the alternate shaft of  FIG. 6 ; 
       FIG. 8  is an end planar view of the alternate shaft of  FIG. 6 ; 
       FIG. 9  is a cross-sectional side planar view of the alternate shaft of  FIG. 6 ; and 
       FIG. 10  is a cross-sectional side planar view of a connector formed in accordance with one embodiment of the present invention showing attachment of an optional workpiece attachment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-4  illustrate a connector  20  formed in accordance with one embodiment of the present invention. The connector  20  is adapted to selectively attach a workpiece  22  to a power tool (not shown). Although the workpiece  22  is illustrated as a Phillips head screwdriver, other workpieces, such as a standard screwdriver and a drill bit, are also within the scope of the present invention. 
   The connector  20  includes a first collar  24 , a spring biased ball pin assembly  26 , a shaft assembly  28 , and a second collar  30 . The workpiece  22  is suitably formed from a high strength material and includes a cylindrical drive portion of the hex stem  32  and an appropriate shaped head portion  34 . The drive portion of the hex stem  32  is sized to be slidably received within the shaft assembly  28  and is seated therein on a spring biased ball pin assembly  26 . 
   The spring biased ball pin assembly  26  includes a coil spring  36 , a ball pin  38 , and a plug  40 . The spring biased ball pin assembly  26  is biased to selectively eject the workpiece  22  from within the connector  20 , as is described in greater detail below. 
   The shaft assembly  28  includes a shaft  42 , collar springs  44 , a ball spring  46 , and centering balls  48 . One end of the shaft  42  is adapted to be received within a corresponding chuck of a well known power tool. The other end of the shaft  42  includes a cavity  50  adapted to lockingly receive the hex stem  32  of the workpiece  22 . Three of the centering balls  48  are disposed around the shaft  42  and are received within corresponding tapered cavities  52 . The centering balls  48  are restrained within the cavities  52  by the ball spring  46 . 
   The shaft  42  also includes a pair of tapered cavities  54  aligned along a longitudinal axis extending between the open ends of the shaft  42 , such that a forward ball  60  is located near the forward or open end of the shaft  42 . A rearward ball  62  is located substantially near a midpoint defined along a longitudinal axis extending between the opened and closed ends of the shaft  42 . 
   Still referring to  FIGS. 1-4 , operation of the connector  20  will now be described in greater detail. To selectively couple the workpiece  22  to the connector  20 , the drive portion of the hex stem  32  of the shaft  42  is inserted into the connector  20 , such that the three centering balls  48  near the front lift up and over a lower portion  33  of the hex stem  32  and drop into a power groove  64 . Continued insertion of the shaft  42  causes the centering balls  48  to lift up and over the power groove  64  and contact the drive portion of the hex stem  32 . The lower portion  33  of the hex stem  32  eventually contacts the ball pin  38  at the back of the shaft&#39;s cavity  50 . The operator then continues to press the workpiece  22  into the connector  20 . This operation causes the ball pin  38 , which is tensioned forward by the coil spring  36  to react until the lower portion  33  of the hex stem  32  presses up against the plug  40 . The plug  40  retains the ball pin  38  and allows clearance for a hex pin  37  found in other optional hex stem configurations, such as the hex pin found in a reversible drill and driver manufactured by Jore Corporation and seen in FIG.  10 . The ball pin  38  retracts rearwardly to allow the rearward ball  62  to drop into its corresponding tapered hole  54  and flush to the diameter of the shaft  42 . This, in turn, allows the first and second collars  24  and  30  to shift forward because it is tensioned towards the forward position. 
   In translating forward, the collar forces the forward ball  60  to drop into its tapered hole  54 , thereby locking the hex stem  32  at the power groove  64 . The collar continues forward to contact the three centering balls  48  located at the front of the connector  20 . The internal taper  100  ( FIG. 4 ) at the front portion of the first collar  24  forces the three centering balls  48  to contact the drive portion of the hex stem  32  and lock it into a centered position. This locking and centering operation takes place by the user simply inserting the workpiece  22  into the connector  20 . 
   To remove the workpiece  22 , the order of operations is basically reversed. The operator pulls the collar back. With this operation, the tension is removed from the centering balls  48  and the ball locking mechanism, comprised of the forward ball  60  and the forward tapered hole  54 . At the end of its travel, the collar allows space for the rearward ball  62  to move back up out of its hole  54  in the shaft  42 . The coil spring  36 , inside the connector  20 , forces the ball pin  38  forward. This in turn forces the rearward ball  62  up and secures the collar in place. The ball pin  38  then moves forward, thus moving the workpiece  22  to a position where the three centering balls  48 , which are tensioned radially inward by the ball spring  46 , move off of the drive portion of the hex stem  32  and drop back into the power groove  64 . The three tensioned balls  48  hold the workpiece  22  at the power groove  64  with a light grip until the operator selectively removes the workpiece  22  from the connector  20 . 
   Referring now to  FIGS. 5-9 , an alternate shaft  142  formed in accordance with the present invention will now be described in further detail. The shaft  142  of the alternate embodiment is identical in materials and operation as the shaft  42  described above with the following exception. As best seen by referring to  FIG. 9 , the aft hole  154  has been relocated to a position 180 degrees (based on a longitudinal axis running down the center of the shaft  142 ) from its position shown in the shaft  42  of the first embodiment of  FIGS. 1-4 . With the ball location change of this alternate embodiment, all of the ball holes are oriented symmetrically around the shaft&#39;s center axis  160 . All other connector components are also symmetric about the axis  160  when in the assembled position. 
   The radial balance of this alternate embodiment helps to minimize centripetal (centrifugal) forces when the connector is rotating in a power drill. Minimizing the forces that result from rotation results in less vibration. This in turn helps utilize the minimized runout capabilities of the connector. Less runout from the hex stem component (drill, nut driver, power bit, etc.) results in easier use, and greater accuracy from the user&#39;s standpoint. For the purposes of this invention, radial balance is defined as the center of mass for the assembly as it is aligned with the axis of rotation for the assembly. 
   While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.

Technology Category: 4