Abstract:
The problem of reaching a work piece, such as a nut on a bolt, in a restricted space not permitting traditional means of applying torque is addressed with a powered wrench. The wrench translates motor power on one axis to an engageable socket on a perpendicular axis through an innovative gearbox. Means are provided to shift from a gear ratio for power to a gear ratio for speed by simple manipulation, while different size work pieces can be accommodated through socket change parts.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This continuation-in-part application is filed under 37 CFR 1.53 and claims benefit under 35 USC 120 to nonprovisional application Ser. No. 11/881,552, filed Jul. 27, 2007. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the general art of tools, and to the particular field of wrenches. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many businesses, such as automobile repair shops, routinely encounter work pieces, such as bolts, nuts or the like, that are extremely difficult to remove or place. The difficulty can be a result of the work piece being fixed-in-place, as by rust or over tightening, or because the work piece is in a location that is difficult to reach. For example, a bolt may be underneath another part that blocks access to it or otherwise inhibits the swinging action of a handle of a tool, such as wrench, while engaging it and applying torque. This makes removal or installation of certain work pieces difficult and time consuming. 
         [0004]    It is often necessary to remove blocking parts to gain access to the work piece of interest with a wrench, such as an open-end or a box-end wrench. There is a need for a wrench that can expeditiously reach and remove work pieces and not require surrounding space for manipulation of the lever-handle. There is also a need to apply sufficient torque without exhaustive human effort. One solution is a powered wrench, wherein torque is supplied to the work-piece-engaging part of the wrench by a motor. 
         [0005]    Such a powered wrench would have a gearbox for transmitting the power. One requirement would be for the gearbox profile to be as small as possible to navigate tight spaces. Another requirement would be for the power to be transmitted through the handle; or, in other words, perpendicular to the axis of the work-piece-engaging part of the wrench. Both requirements are met by a worm gearbox. 
         [0006]    In a worm gearbox, a screw transmits power to a spur gear. The axes of the screw, or worm, and the spur gear are perpendicular. Such an arrangement is typically smaller than other configurations having the same gearing ratio and involving multiple spur gears. Sometimes the gear train includes an intermediate, or idler, gear between the worm gear and the spur gear doing the work, or drive gear. This configuration allows different spatial arrangements of the gear system. 
         [0007]    As known in the art, it takes a complete revolution of the worm gear to advance the drive gear one tooth. A 30-tooth drive gear, for example, would have a 30:1 reduction in speed and a complementary 30:1 increase in torque. It should be noted that the idler gear is inconsequential with respect to the gear ratio since it transmits motion but does not contribute any mechanical advantage. This low-speed-high-torque gearing arrangement is particularly well matched to motor drives, which drives characteristically produce high revolution speed with low torque. 
         [0008]    Worm gear configurations for powered wrenches are known in the art. For example, in U.S. Pat. No. 6,543,313 to Samudosky et al, a prior patent of the instant inventor which is incorporated herein by reference, a worm gearing arrangement driving a chain sprocket is disclosed. The chain provides an adaptable means for engaging the work piece. The chain, however, is subject to breakage and, on occasion, slippage. 
         [0009]    U.S. Pat. No. 858,892 to Moss teaches a worm gearing arrangement to drive a spur gear with a box recess to engage a nut. The box recess provides a firm and virtually unbreakable grip on the work piece. Adaptation to smaller work pieces is provided by inserts to the box recess similar to socket-wrench sockets. Moss uses an idler gear to make the layout compact for tight spaces. The drive force, however, is supplied by twisting the handle by hand and is not supplied by motor. This twisting can be fatiguing for the operator, particularly considering the slow speed of the operation. 
         [0010]    Considering that higher torque is usually only needed in the initial loosening of a work piece, such as a nut, and that the subsequent unthreading of the nut following its loosening is characterized by lower frictional forces, it would be desirable to have a means to switch from high torque to lower torque, and, in doing so, to hasten the speed of the action. Furthermore, not all work pieces require the same initial “breaking” torque. However, a wrench designed to be powerful enough for the occasional “frozen” nut, will of necessity be slow in operation. What is needed in such cases is a dual-speed option. 
         [0011]    U.S. Pat. No. 3,272,037 to Bruehl describes a wrench having dual speeds. The slow speed is provided in a manner similar to Moss above. The fast speed is provided by a ratchet mechanism enabling the handle to be used in the conventional way, that is, by swinging the handle by hand. This does not solve the problem for a restricted space, however, because there would be insufficient room to swing the handle. 
         [0012]    What is missing in the prior art is a gear-driven motor-powered wrench for fitting into tight spaces with a changeable gear ratio providing both slow and fast speeds. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    In view of the above-mentioned unfulfilled needs in the prior art, the present invention embodies the objects and advantages detailed herein: 
         [0014]    A first object of the present invention is to provide a powered wrench for tight spaces where room for conventional handle-action is restricted. 
         [0015]    A second object of the present invention is to provide a powered wrench having a socket engagement to securely grip a work piece. 
         [0016]    A third object of the present invention is to provide a socket engagement adaptable to different sized and shaped work pieces. 
         [0017]    A fourth object of the present invention is to provide a 60:1 gear ratio for low speed and high torque. 
         [0018]    A fifth object of the present invention is to provide a 30:1 gear ratio for high speed and low torque. 
         [0019]    A sixth object of the present invention is to provide a means for switching between gear ratios without disassembly of the wrench. 
         [0020]    In a preferred embodiment of the present invention, a powered wrench comprises a housing having a handle part and a gear part. The handle part has a longitudinal extent with a worm gear mounted therein, the worm gear having a shaft extending through the handle part to connect to a remote motor drive. A bore extends through the gear part of the housing such that the axis of the bore is perpendicular to the axis of the shaft. 
         [0021]    A means for gearing is housed in the gear part and connected to the worm gear through a means for connecting. The means for gearing is comprised of a first gear ratio, a second gear ratio and a means for shifting therebetween. The first gear ratio represents a power mode and the second gear ratio, a speed mode of operation. A means for engaging a work piece through the bore is connected to the means for gearing. 
         [0022]    In another aspect of the preferred embodiment, a method of using the powered wrench comprises the steps of connecting to the motor, engaging the work piece, selecting the first gear ratio, applying power to loosen the work piece, selecting the second gear ratio, and applying power again to remove the work piece quickly. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0023]    Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood through the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
           [0024]      FIG. 1  is a perspective view of the powered wrench from the top; 
           [0025]      FIG. 2  is an inside perspective view showing the gears in engagement for the first, or power, gear ratio; 
           [0026]      FIG. 3  is a truncated perspective view of the worm gear and shaft; 
           [0027]      FIG. 4  is a perspective view of the idler gear from the bottom showing the spindle; 
           [0028]      FIG. 5  is a perspective view of the gear stack from the bottom showing the first and second spur gears; 
           [0029]      FIG. 6  is a perspective view of the gear stack from the top showing the first spur gear and one of the hub protrusions; 
           [0030]      FIG. 7  is a perspective view of the bottom showing the first and second means for locking in position for the first gear ratio; 
           [0031]      FIG. 8  is a partial sectional inside perspective view showing the gears in engagement for the first, or power, gear ratio; 
           [0032]      FIG. 9  is an inside perspective view showing the gears engaged for the second, or speed, gear ratio; 
           [0033]      FIG. 10  is a perspective view of the bottom showing the first and second means for locking in position for the second gear ratio; 
           [0034]      FIG. 11  is a partial sectional inside perspective view showing the gears in engagement for the second, or speed, gear ratio. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]      FIGS. 1 and 2  show the principal components of the assembled powered wrench  1 . Housing  10  is divided into a handle part  11  and a gear part  12 . Housing  10  is further sectioned by cover part  15  and base part  14 , the cover and base parts providing a means for accessing  13  an interior space  18 . Interior space  18  is revealed in  FIG. 2 , where cover part  15  has been removed. Positioned in interior space  18  is a means for gearing  30 , a means for connecting  40 , and a shaft  20 . The gear part  12  has a bore  16  extending through both cover part  15  and base part  14 . 
         [0036]    Referring to  FIG. 3 , shaft  20  has a proximal end  21  and a distal end  22 . A worm gear  24  is positioned at proximal end  21  and extends into gear part  12 . Distal end  22  connects to motor drive  25  (not shown). Shaft  20  is rotatably mounted in handle part  11 , best shown in  FIG. 2 , and has a first axis of rotation  23  which is coincident with a longitudinal axis  17  of the handle part. 
         [0037]    The means for gearing  30  is best detailed in  FIGS. 5 and 6 . A first spur gear  33 , having a first number of teeth  34  defining a first gear ratio  31 , is coaxially joined in gear stack  37  with a second spur gear  35 , having a second number of teeth  36  defining a second gear ratio  32 . The gear stack  37  has a second axis of rotation  38 , best shown in  FIG. 2 , which is perpendicular to the first axis of rotation  23 . In a preferred embodiment, the first number of teeth is 60 and the first gear ratio, defining a power mode, is 60:1. Further, the second number of teeth is 30 and the second gear ratio, defining a speed mode, is 30:1. 
         [0038]    The means for gearing  30  is in meshing engagement with worm gear  24  through means for connecting  40 , best shown in  FIG. 4 . The means for connecting  40  comprises idler gear  41  with a protuberant spindle  42  at its center. Rail  43  registers the elevation of idler gear  41  above base part  14 , to which idler gear  41  is rotatably and moveably connected. Rail  43  additionally provides a reduced contact surface for rotating purposes. In connecting, spindle  42  extends through a slot  19  in base part  14 , best shown in  FIG. 7 , and can move therein from one end of slot  19  to the other. Slot  19  has a longitudinal aspect parallel to longitudinal axis  17 . Idler gear  41  remains in meshing contact with worm gear  24  throughout the movement in slot  19 . Idler gear  41  can have any number of teeth, but is shown in the preferred embodiment as having 30. Idler gear  41  transfers the rotation from first axis of rotation  23  perpendicularly into rotation on second axis of rotation  38 , as may be known in the art for worm gearboxes, while transferring power from worm gear  24  to one of spur gear  33  or spur gear  34 . The spatial adjustment to the spur gears is achieved by translational movement of idler gear  41  in slot  19 . The enmeshment of worm gear  24 , idler gear  41  and first spur gear  33  is best shown in  FIG. 2 . 
         [0039]      FIGS. 8 and 11  illustrate a means for shifting  50  between the first gear ratio  31  and the second gear ratio  32 . Hub protrusions  51  extend from gear stack  37  in both directions along second axis  38 . Hub protrusions  51  extend sufficiently to traverse bore  16  and protrude though both cover part  15  and base part  14  at all times, including when they have shifted along second axis  38 . Hub protrusions  51  are slidingly fixtured by sidewalls  52  of the cover and base parts, the sidewalls framing bore  16 . The translational movement of gear stack  37  along second axis  38  guided by hub protrusions  51  in sidewalls  52  shifts between the engagement of first spur gear  33  with idler gear  41  and the engagement of second spur gear  35  and idler gear  41 . This translational movement can be accomplished by pushing on the most protrubing of the hub protrusions  51  with hand-applied pressure. The engagement of first spur gear  33  with idler gear  41  located at one end of slot  19  is shown in  FIGS. 2 and 8 , and the engagement of second spur gear  35  with idler gear  41  located at the other end of slot  19  is shown in  FIGS. 9 and 11 . 
         [0040]    A means for engaging  60  to a work piece  2  (not shown) is illustrated in  FIG. 1 . A socket aperture  61  extends along second axis  38  through hub protrusions  51  and gear stack  37  to form engagement head  63 . Engagement head  63  turns in a clockwise direction on one side of powered wrench  1  and turns in a counterclockwise direction on the other side. Thus reversal of action can be achieved without a reversible motor by flipping the powered wrench over. Socket aperture  61  is configured for a commonly-used work piece profile. Other work pieces can be accommodated through a plurality of socket inserts  62  (not shown) with structures that engagingly fit into socket aperture  61 , common in the art of wrench sockets, and are configured to alternate work piece profiles. Because both the means for gearing  30  and the means for connecting  40  are moveable, some means for locking positions is required to maintain gear contact. Accordingly, means for connecting  40  is provided with a first means for locking  70 , as shown in  FIGS. 7 and 10 , where the bottom of base part  14  is facing. One of two recesses  71  in the exterior of base part  14  is centered at each end of slot  19 . A channel  72  provides a communicating link between the two recesses. A bar  73  is rotatably attached to spindle  42  by any known means, for example, a clevis pin  76 , and thereby slidingly secures idler gear  41  in slot  19  with rail  43  riding on an inside surface of base part  14  and bar  73  riding within the two recesses  71  and channel  72 . The bar  73  has a long dimension  74  and a short dimension  75 , which latter dimension is broader than slot  19 . Each of the two recesses  71  has a diameter substantially matching the long dimension  74 , such that bar  73  is rotatable within the recess. Also, channel  72  has a width substantially matching the short dimension  75 , such that the bar can pass through the channel. The idler gear  41  is moveable in slot  19  parallel to the longitudinal axis  17  when bar  73  is in align position  78  (not shown), characterized by the longitudinal alignment of bar  73  and channel  72 . Alternatively, idler gear  41  is locked in position at either extreme of slot  19  when bar  73  is in lock position  77 , characterized by the rotation of bar  73  out of alignment in one of the two recesses  71 . The lock position  77  corresponding to the engagement of the first spur gear  33  is shown in  FIG. 7 , and the lock position  77  corresponding to the alternative engagement, that of second spur gear  35 , is shown in  FIG. 10 . 
         [0041]    Means for shifting  50  is similarly provided with a second means for locking  80 . Annular slots  81  are located at the peripheries of hub protrusions  51 , such that at least one of the annular slots  81  is exposed to the exterior of housing  10  when gear stack  37  is shifted for a change of gears. Annual slots  81  are best shown  FIGS. 8 and 11 . A pair of latches  82  is rotatably mounted to the exterior surfaces of cover part  15  and base part  14  such that the latches can be rotating into interposition with the annual slots  81  when the latter is shifted into proximity. The pair of latches  82  is nested in latch cavities  85  where the configuration of the cavities limit the rotation of the latches between an interlock position  83  and a disengage position  84 . The interlock position  83  is characterized by the engagement of one of the pair of latches  82  in the one of the annular slots  81  in juxtaposition to it, the other of the pair of latches  82  occupying the disengage position. The pair of latches  82  and the latch cavities are best shown in  FIGS. 7 and 10 . The lock position  83  is best shown in  FIGS. 7 and 8 , while the disengage position  84  is shown in  FIGS. 1 and 10 . The lock position  83  is further characterized by a sense of rotation, that is to say, clockwise or counterclockwise, that matches the sense of the worm gear  24 . It this were otherwise, the rotation of the gear stack would throw the engaged latch to the disengage position. 
         [0042]    Thus it can be seen that a powered wrench, driven by a motor through connecting means for gearing, can apply torque through a means for engaging to variable work pieces in one of two scenarios, the first representing higher torque and lower speed and the second representing lower torque and higher speed, by selecting different gear ratios through a means for shifting accessible from the exterior of the powered wrench. 
         [0043]    The housing components of the powered wrench may be comprised of any tough injection-molded thermoplastic material or any metal. In the preferred embodiment, the material of choice is ABS. The gears may be comprised of steel and fabricated by machining. The gears are machined tool steel in the preferred embodiment. The remaining components may be either of metal or plastic composition and fabricated by stamping or molding. 
         [0044]    It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the preceding description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of the description and should not be regarded as limiting.