Abstract:
A ratchet mechanism includes a base and a shaft having gear teeth rotatably mounted on the base. A bearing is mounted on the base and is rotatable to clockwise and counterclockwise positions, and includes first and second bearing magnets. First and second pawls are slidably positioned on the base, and are slidable between engaged and disengaged positions in which the pawls engage and disengage, respectively, the gear teeth. First and second pawl magnets are embedded in the first and second pawls in magnetic relation to the first and second bearing magnets such that when the bearing is rotated to the clockwise or counterclockwise positions, the first and second bearing magnets bias the first and second pawl magnets to cause the first and second pawls to slide to respective engaged and disengaged positions, or disengaged and engaged positions, thereby enabling the shaft to rotate one of clockwise or counterclockwise directions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. patent application Ser. No. 14/677,698, filed Apr. 2, 2015, which application is hereby incorporated herein by reference, in its entirety. 
       TECHNICAL FIELD 
       [0002]    The invention relates generally to ratchets and, more particularly, to ratchets for screwdrivers, socket wrenches, and the like. 
       BACKGROUND 
       [0003]    Screwdrivers and socket wrenches are well-known for their ability to tighten and loosen fasteners, such as screws, bolts, and the like. A drawback with many screwdrivers and socket wrenches, though, is that, while tightening or loosening a fastener, a user must continually tighten his grip while turning the screwdriver in one direction, and loosen his grip when turning the screwdriver in the other direction. One solution to such a drawback is to integrate a ratchet to the screwdriver or socket wrench, so that the ratchet controls the application of torque to a screwdriver or socket wrench, to tighten or loosen a fastener. A problem with traditional ratchets, though, is that the pawls which engage and disengage the ratchet gear are biased using leaf or coil springs which contact both the pawl and the ratchet housing and therefore transmit vibration and noise from the pawls to the ratchet housing. A further problem with traditional ratchets is that, in order for the springs to push on the pawls, enough space must be available for the pawls to sit between the spring and the gear, making the ratchet mechanism large and cumbersome. Ratchets using one-way bearings rather than pawls and gears have been used to eliminate noise vibration and friction, but such bearings are bulky and only allow clockwise and counter-clockwise operation, and do not allow a third position which is bi-directional, or locked for transferring torque in both directions. 
         [0004]    Therefore, what is needed is a ratchet that may be integrated with a screwdriver or socket wrench and that has less noise and vibration than traditional ratchets, and that is also smaller than traditional ratchets, while also allowing clockwise, counter-clockwise, and bi-directional operation of the ratchet. 
       SUMMARY 
       [0005]    The present invention, accordingly, provides a ratchet mechanism having a base preferably mounted to a handle, wherein the base defines a first pawl cavity, a second pawl cavity, and a shaft bore. A shaft is rotatably positioned in the shaft bore, wherein the shaft includes gear teeth circumscribing at least a portion of the shaft proximate to the pawl cavities. The shaft further includes a driver at an end thereof, the driver being, for example, a socket to which any of a number of bits may be mounted. By way of example, but not limitation, bits may be of any suitable or desirable shape, such as a slotted (flat) head, a Philips head, a square or hex socket, spanner head, spline drive, or the like. 
         [0006]    A bearing is mounted on the base, and is selectively rotatable to at least a clockwise position for enabling clockwise rotation of the shaft, and a counterclockwise position for enabling counterclockwise rotation of the shaft. The bearing includes a first bearing magnet and a second bearing magnet mounted in the bearing. 
         [0007]    A first pawl is slidably positioned in the first pawl cavity of the base, and is slidable between an engaged position in which the first pawl engages the gear teeth, and a disengaged position in which the first pawl is not engaged with the gear teeth. A first pawl magnet is embedded in the first pawl in magnetic relation to the first bearing magnet such that when the bearing is rotated to the clockwise position, the first bearing magnet biases the first pawl magnet to cause the first pawl to slide to the engaged position, and when the bearing is rotated to the counterclockwise position, the first bearing magnet biases the first pawl magnet to cause the first pawl to slide to the disengaged position. 
         [0008]    A second pawl is slidably positioned in the second pawl cavity of the base, and is slidable between an engaged position in which the second pawl engages the gear teeth, and a disengaged position in which the second pawl does not engage the gear teeth. A second pawl magnet is embedded in the second pawl in magnetic relation to the second bearing magnet such that when the bearing is rotated to the clockwise position, the second bearing magnet biases the second pawl magnet to cause the second pawl to slide to the disengaged position, and when the bearing is rotated to the counterclockwise position, the second bearing magnet biases the second pawl magnet to cause the second pawl to slide to the engaged position. 
         [0009]    In a further embodiment, the bearing may be rotated to a bi-directional position between clockwise and counterclockwise positions to allow torque to be transmitted in both clockwise and counterclockwise directions. 
         [0010]    In a still further embodiment, the pawls are fabricated from a ferromagnetic material, and a magnet is positioned in the base for biasing each respective pawls to engage the gear teeth. A pin extends upwardly from each pawl into a respective hole of a bearing for restraining a first pawl from engaging the gear teeth in a first direction, and for restraining a second pawl from engaging the gear teeth in a second direction. 
         [0011]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed 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 
         [0012]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
           [0013]      FIG. 1  is a perspective view of a screwdriver embodying features of the present invention; 
           [0014]      FIG. 2  is a cross-section of the screwdriver of  FIG. 1  taken along line  2 - 2  of  FIG. 1 ; 
           [0015]      FIG. 3  is a perspective view of a ratchet mechanism embodying features of the present invention; 
           [0016]      FIG. 4  is a cross-section of the ratchet mechanism taken along line  4 - 4  of  FIG. 3 ; 
           [0017]      FIG. 5A  is a cross-section of the ratchet mechanism taken along line  5 - 5  of  FIG. 4 , and magnetically biased to transfer torque in two directions; 
           [0018]      FIG. 5B  is a cross-section of the ratchet mechanism taken along line  5 - 5  of  FIG. 4 , and magnetically biased to transfer torque in a first direction; 
           [0019]      FIG. 5C  is a cross-section of the ratchet mechanism taken along line  5 - 5  of  FIG. 4 , and magnetically biased to transfer torque in a second direction; 
           [0020]      FIG. 6  is a perspective view of an alternative embodiment of the ratchet mechanism embodying features of the present invention; 
           [0021]      FIG. 7  is a cross-section of the ratchet mechanism taken along line  7 - 7  of  FIG. 8A ; 
           [0022]      FIG. 8A  is a cross-section of the ratchet mechanism taken along line  8 - 8  of  FIG. 7 , and magnetically biased to transfer torque in two directions; 
           [0023]      FIG. 8B  is a cross-section of the ratchet mechanism taken along line  8 - 8  of  FIG. 7 , and magnetically biased to transfer torque in a first direction; 
           [0024]      FIG. 8C  is a cross-section of the ratchet mechanism taken along line  8 - 8  of  FIG. 7 , and magnetically biased to transfer torque in a second direction; 
           [0025]      FIG. 9  is a perspective view of a further alternative embodiment of the ratchet mechanism embodying features of the present invention; 
           [0026]      FIG. 10  depicts a bearing utilized in the alternative embodiment of  FIG. 9 ; 
           [0027]      FIG. 11  depicts the bearing of  FIG. 10  assembled to the embodiment of  FIG. 9 ; 
           [0028]      FIG. 12  is cross-section of the embodiment of  FIG. 11  taken along the line  12 - 12  of  FIG. 11 ; 
           [0029]      FIG. 13A  is a cross-section of the ratchet mechanism of  FIG. 12  taken along line  13 - 13  of  FIG. 12 , and magnetically biased to transfer torque in two directions; 
           [0030]      FIG. 13B  is a cross-section of the ratchet mechanism of  FIG. 12  taken along line  13 - 13  of  FIG. 12 , and magnetically biased to transfer torque in a first direction; and 
           [0031]      FIG. 13C  is a cross-section of the ratchet mechanism of  FIG. 12  taken along line  13 - 13  of  FIG. 12 , and magnetically biased to transfer torque in a second direction. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Refer now to the drawings wherein depicted elements are, for the sake of clarity, not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views. The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. Additionally, as used herein, the term “substantially” is to be construed as a term of approximation. Refer now to the drawings wherein like or similar elements are designated by the same reference numeral through the several views. 
         [0033]    Referring to  FIG. 1  of the drawings, the reference numeral  100  generally designates a screwdriver having a ratchet embodying features of the present invention. The screwdriver  100  includes a handle portion  102 , a shaft  106  extending from the handle portion  102  to a driver  108 , and a ratchet  104  interposed between the handle portion  102  and driver  108 , all of which portions will be described in further detail below.  FIG. 2  is a cross-sectional view of the screwdriver  100  of  FIG. 1   
         [0034]      FIG. 3  is a perspective view of the ratchet  104 , and  FIG. 4  is a cross-sectional view of the ratchet  104  taken along the line  4 - 4  of  FIG. 3 . The ratchet  104  includes a base  110  which defines a well  110   a  and two pawl cavities  416  and  414 . The well  110   a  extends into and is secured in the handle  102 . A shaft  106 , including gear teeth  106   a , is rotatably mounted in the well  110   a , and preferably includes roller and thrust bearing  401  positioned in the bottom of the well between the shaft  106  and the well  110   a . Pawls  304  and  306  are slidably positioned in pawl cavities  414  and  416 , respectively, for engaging gear teeth  106   a . Magnets  310  and  312  are embedded in pawls  304  and  306 , respectively, and are flush with the upper surface of respective pawls. An upper bearing  322  is rotatably secured atop ratchet base  110  for imparting upper rotational stability to shaft  106 , and is secured in any convention manner (e.g., mating tab and cutout) for synchronous rotation with the ratchet cover  302 . Magnets  314  and  316  are embedded in upper bearing  322  for magnetically biasing magnets  310  and  312 , respectively, as discussed further below with respect to  FIGS. 5A-5C . A ratchet cover  302  is preferably positioned over the bearing  322  and ratchet base  110  and is seated on the screwdriver handle  102 . It may thus be appreciated that upper bearing  322  and magnets  314  and  316  move synchronously with ratchet cover  302 . In an alternative embodiment, upper bearing  322  and magnets  314  and  316  may be integrated into ratchet cover  302 . 
         [0035]      FIGS. 5A-5C  are cross-sectional views of the ratchet  104  taken along the line  5 - 5  of  FIG. 4 , showing three different modes of operation of the ratchet. To establish a mode, ratchet base  110  and ratchet cover  302  are preferably provided with conventional complementary ball and detents operable to secure the ratchet cover relative to the ratchet base in three user-selectable positions corresponding to the three modes of operation. Specifically, in a preferred embodiment, the ratchet base  110  defines a bore  508  sized for receiving a spring  506  compressed for urging a ball  504  outwardly from the ratchet base  110 . Ratchet cover  302  preferably defines three complementary detents  502   a ,  502   b , and  502   c  positioned so that one of the three detents receives ball  504  for each mode the ratchet is selectively set to, and secures the ratchet in such selected position for operation, discussed below. It is understood that the complementary ball and detents may be configured at locations between the ratchet base  110  and ratchet cover  302  that differ from that shown in  FIGS. 5A, 5B, and 5C , as well as  FIGS. 8A, 8B, 8C, 13A, 13B, and 13C  discussed below. Furthermore, it is considered that complementary ball and detents are well-known in the art for securing complementary parts in selected positions and, therefore, will not be discussed in further detail herein, except to the extent necessary to explain operation of the invention. 
         [0036]      FIG. 5A  exemplifies a first, or bi-directional, mode or operation of the ratchet  104  in which the shaft  106  rotates synchronously with the handle  102  to transfer torque in both clockwise and counterclockwise directions. Accordingly, the ratchet cover  302 , and hence upper bearing  322  and magnets  314  and  316  which move synchronously with the ratchet cover, as discussed above, is rotated relative to the ratchet base  110  so that ball  504  is seated in a middle, or bi-directional, detent  502   a . The magnets  314  and  316  are then positioned to bias magnets  310  and  312 , as well as pawls  304  and  306 , downwardly, as viewed in  FIG. 5A , thereby causing each pawl to engage gear teeth  106   a  of shaft  106 . Pawl  304  imparts clockwise rotation of shaft  106 , and pawl  306  imparts counterclockwise rotation of shaft  106 . It may be appreciated then that, in the first mode, shaft  106  rotates synchronously with the handle  102  to transfer torque in both clockwise and counterclockwise directions. 
         [0037]      FIG. 5B  exemplifies a second mode of operation of ratchet  104  in which shaft  106  rotates synchronously with the handle  102  to transfer torque in a counterclockwise direction, but not in a clockwise direction, a mode commonly used to loosen fasteners, such as screws. Accordingly, the ratchet cover  302 , and hence upper bearing  322  and magnets  314  and  316  as discussed above, is rotated clockwise relative to the ratchet base  110  and handle  102  so that ball  504  is seated in a corresponding detent  502   b . The magnets  314  and  316  are then positioned to bias magnet  310  and pawl  304  upwardly, and to bias magnet  312  and pawl  306  downwardly, as viewed in  FIG. 5B , causing pawl  306  to engage gear teeth  106   a  of shaft  106 , and causing pawl  304  to disengage from gear teeth  106   a  of shaft  106 . It may be appreciated then that, in the second mode, when a user turns handle  102  in a tightening (i.e., clockwise) direction, pawl  306  skips over one or more gear teeth  106   a  while maintaining contact with gear teeth  106   a  under bias from magnet  316 , and shaft  106  does not turn with handle  102 , and torque is not transferred from handle  102  to shaft  106 . However, as soon as a user turns handle  102  in a loosening (i.e., counterclockwise) direction, pawl  306  engages a gear tooth  106   a , and shaft  106  turns with handle  102 , and torque is transferred from handle  102  to shaft  106 . 
         [0038]      FIG. 5C  exemplifies a third mode of operation of ratchet  104  in which shaft  106  rotates synchronously with handle  102  to transfer torque in a clockwise direction, but not in a counterclockwise direction, a mode commonly used to tighten fasteners, such as screws. Accordingly, ratchet cover  302 , and hence upper bearing  322  and magnets  314  and  316  as discussed above, are rotated counterclockwise relative to ratchet base  110  and handle  102  so ball  504  is seated in corresponding detent  502   c . The magnets  314  and  316  are then positioned to bias magnet  310  and pawl  304  downwardly, and to bias magnet  312  and pawl  306  upwardly, as viewed in  FIG. 5C , causing pawl  306  to disengage from gear teeth  106   a  of shaft  106 , and causing pawl  304  to engage gear teeth  106   a  of shaft  106 . It may be appreciated then that, in the third mode, when a user turns handle  102  in a loosening (i.e., counterclockwise) direction, pawl  304  skips over one or more gear teeth  106   a  while maintaining contact with gear teeth  106   a  under bias from magnet  312 , and shaft  106  does not turn with handle  102 , and torque is not transferred from handle  102  to shaft  106 . However, as soon as a user turns handle  102  in a tightening (i.e., clockwise) direction, pawl  304  engages a gear tooth  106   a , and shaft  106  turns with handle  102 , and torque is transferred from handle  102  to shaft  106 . 
         [0039]      FIGS. 6-8C  exemplify an alternative embodiment  604  of the ratchet, similar to embodiment  104  of  FIGS. 3-5C , but wherein pegs are used to mechanically disengage one of pawls  304  and  306  from gear teeth  106   a . Accordingly, as most clearly shown in  FIG. 7 , pegs  614  and  616  are embedded in bearing  322  (or, alternatively, in the ratchet cover  302  if the bearing is integrated into the ratchet cover) and extend downwardly. It may thus be appreciated that, along with upper bearing  322  and magnets  314  and  316 , pegs  614  and  616  also move synchronously with ratchet cover  302 . As shown most clearly in  FIGS. 8A-8C , pawl cavities  714  and  716  are defined in ratchet base  110  similarly to pawl cavities  414  and  416 , but extended downwardly for receiving pegs  614  and  616 . Ratchet  604  is otherwise similar to ratchet  104 . 
         [0040]    As discussed above with respect to ratchet  104 , ratchet  604  is operable in three modes. In the first mode, depicted in  FIG. 8A , both pawls  304  and  306  engage a gear tooth  106   a , thereby transmitting torque from handle  102  to shaft  106  in both clockwise and counterclockwise directions. Hence, in the first mode of operation, when a user turns handle  102  in either direction, torque is transferred to turn shaft  106  in the same direction. Operation in the first mode is otherwise similar to that described above with respect to  FIG. 5A . 
         [0041]    In the second mode, depicted by  FIG. 8B  for transmitting torque from handle  102  to shaft  106  in a counterclockwise (i.e., loosening) direction, pawl  304  is urged upwardly (as viewed in  FIG. 8B ) by peg  614  to thereby prevent pawl  304  from engaging gear teeth  106  and transmitting torque in a clockwise (i.e., tightening) direction. Operation in the second mode is otherwise similar to that described above with respect to  FIG. 5B . 
         [0042]    In the third mode, depicted by  FIG. 8C  for transmitting torque from handle  102  to shaft  106  in a clockwise (i.e., tightening) direction, pawl  306  is urged upwardly (as viewed in  FIG. 8C ) by peg  616  to thereby prevent pawl  306  from engaging gear teeth  106  and transmitting torque in a counterclockwise (i.e., loosening) direction. Operation in the third mode is otherwise similar to that described above with respect to  FIG. 5C . 
         [0043]      FIGS. 9-13  exemplify an alternative embodiment  904  of the ratchet, similar to embodiments  104  and  604  of  FIGS. 3-8C . Unlike ratchets  104  and  604 , ratchet  904  utilizes pawls  1304  and  1306  which are fabricated from a magnetic material, preferably a ferromagnetic material such as iron, nickel, cobalt, or the like, that are attracted to magnetic fields. Magnets  1114  and  1116  are positioned adjacent respective pawls  1304  and  1306  in magnet cavities  1118  and  1120  defined in base  1310 , corresponding to base  110  in ratchets  104  and  604 . As so positioned, magnets  1114  and  1116  bias respective pawls  1304  and  1306  toward the magnets. Pawls  1304  and  1306  further preferably include pins  1110  and  1112  press-fitted in them and extending upwardly. Alternatively, the pawls and respective pins may be fabricated as a single integral part. 
         [0044]    Ratchet  904  further includes a bearing  1322 , shown most clearly in  FIG. 10 , and corresponding to bearing  322  of ratchets  104  and  604 . Bearing  1322  is preferably fabricated from plastic, nylon, or other suitable material. Further, bearing  1322  defines two holes (or, alternatively, cavities)  1314  and  1316 , for receiving and engaging pins  1110  and  1112 , as discussed in further detail below. Two notches  1330  are defined in bearing  1322  for engaging ratchet cover  302  to facilitate synchronous movement of bearing  1322  and holes  1314  and  1316  with ratchet cover  302 . 
         [0045]      FIG. 11  depicts the assembly of ratchet  904  wherein bearing  1322 , shown in dashed outline, is positioned over pawls  1304  and  1306  and magnets  1114  and  1116  so that pins  1110  and  1112  extend through holes  1314  and  1316  of bearing  1322 . While not shown in  FIG. 11 , ratchet cover  302  fits over bearing  1322  so that notches  1330  engage teeth on the interior of the ratchet cover to facilitate synchronous rotation movement between bearing  1322  and ratchet cover  302 . Alternatively, bearing  1322  may be integrated into the ratchet cover as a single unit, with a similar function as described herein. 
         [0046]      FIG. 12  depicts a cross-section of  FIG. 11  taken along the line  12 - 12  of  FIG. 11 . As shown therein, magnet  1114  attracts the magnetic material of pawl  1304  toward the magnet, but the pawl is restrained in its movement by pin  1110  extending upwardly from the pawl engaging hole  1314  of bearing  1322  (similar to the position depicted by  FIG. 13B , discussed below). It can be appreciated that the position of pawl  1304  may thereby be controlled by bearing  1322 , which a user can control by turning ratchet cover  302  in one of three modes, discussed below. 
         [0047]    As discussed above with respect to ratchets  104  and  604 , ratchet  904  is operable in three modes. In the first mode, depicted by  FIG. 13A , holes  1314  and  1316  of bearing  1322  allow both pawls  1304  and  1306  to engage a gear tooth  106   a , thereby transmitting torque from handle  102  to shaft  106  in both clockwise and counterclockwise directions. Hence, in the first mode of operation, when a user turns handle  102  in either direction, torque is transferred to turn shaft  106  in the same direction. Operation in the first mode is otherwise similar to that described above with respect to  FIG. 5A . 
         [0048]    In the second mode, depicted by  FIG. 13B  for transmitting torque from handle  102  to shaft  106  in a counterclockwise (i.e., loosening) direction, hole  1316  of bearing  1322  allows pawl  1306  to be drawn closer to magnet  1116  and engage a gear tooth  106   a . At the same time, pawl  1304  is urged away from magnet  1114  by pin  1110  to thereby prevent pawl  1304  from engaging gear teeth  106   a  and cause torque to be transmitted in a clockwise (i.e., tightening) direction. Operation in the second mode is otherwise similar to that described above with respect to  FIG. 5B . 
         [0049]    In the third mode, depicted by  FIG. 13C  for transmitting torque from handle  102  to shaft  106  in a clockwise (i.e., tightening) direction, hole  1314  of bearing  1322  allows pawl  1304  to be drawn closer to magnet  1114  and engage a gear tooth  106   a . At the same time, pawl  1306  is urged away from magnet  1116  by pin  1112  to thereby prevent pawl  1306  from engaging gear teeth  106   a  and cause torque to be transmitted in a counterclockwise (i.e., loosening) direction. Operation in the third mode is otherwise similar to that described above with respect to  FIG. 5C . 
         [0050]    It is understood that the present invention may take many forms and embodiments. Accordingly, several variations may be made in the foregoing without departing from the spirit or the scope of the invention. For example, magnets  310 ,  312 ,  314 , and  316  could be repositioned to enable a mode wherein torque is not transferred in either clockwise or counterclockwise directions. In ratchet  904 , pawls  1304  and  1306 , or a portion thereof, may also be magnetized and oriented to increase the effective magnetic attraction between pawls  1304  and  1306  and magnets  1114  and  1116 . Magnets  1114  and  1116  may also be configured as a Halbach array of permanent magnets to further increase their effective magnetic force. 
         [0051]    Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.