Abstract:
A driving tool includes a shank, a sleeve, and a return spring disposed therebetween. The shank has a ball recess with a ball received therein. The shank has an interior interface adapted for receiving a tool bit. The ball recess substantially extends into the interior interface. The sleeve mounts on the shank to slide between limits. The sleeve has a first interior ball release recess followed by an interior ball lock surface and then a second interior ball release recess. The release recesses and surface are oriented with respect to the ball recess so as to permit selective displacement of the same over the ball recess to unlock the ball with movement in either direction. A return spring is disposed between the shank and the sleeve. The spring has a first and second end. One of the ends of the spring acts against a feature fixed with the shank and the other end of the spring acts against a feature fixed with the sleeve in a manner so as to permit selective displacement of the ball release recess and lock surface over the ball recess. The position of least spring potential energy is the position with the surface located just above the ball recess so as to tend to lock the ball into engagement with tool bit when the sleeve is in a rest position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part application of U.S. patent application Ser. No. 11/244,301, filed Oct. 5, 2005 now abandoned, entitled-RATCHET HANDLE, which claims priority to U.S. Provisional patent application Ser. No. 60/678,245, filed on May 5, 2005, the contents of which are incorporated herein by reference thereto and relied upon. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to drivers for rotary surgical cutting tools, and, more particularly, to drivers used in maxillo-facial, neuro, dental and orthopedic surgery, including reamer drivers. 
     Screwdrivers, ratchet drivers, and other hand-held tools are often utilized to insert, remove and/or adjust fasteners attached to various items. The tool is used to rotate the fasteners into or out of apertures in the items to properly position the fasteners with respect to the items. In ratchet drivers, the rotation is controlled such that there is relatively free rotation in one direction and driven, locked rotation in the opposite direction. 
     Such tools include a coupling device which retains an insert used to drive the fastener or other item. With regards to ratchet tools, users have differing preferences and adhere to varying conventions as to what constitutes intuitive actuation of a mechanism. Because of this, manufacturers must provide different models which, for example, provide the user with a selection of operation that suits his preferences. For example, focus group studies have shown that some users intuitively associate a pushing action with engaging a tool to an insert. Among these users, a significant portion believes that the same action should also enable disengagement of the insert for insertion of a new insert. At the same time, other users polled associate a pulling action to engagement. Among these users, the same action should also enable disengagement of the insert for insertion of the new insert. The remaining believes that a combination of pushing and pulling should engage and/or disengage the insert. Because the prior art ratcheting mechanisms generally include a large number of parts assembled within the housing in order to complete the ratcheting and actuation mechanisms, a large inventory of the differing parts necessary to provide the user with the engagement/disengagement action they intuitively prefer. The complexity of these mechanisms increase the time and expense necessary for manufacturing tools incorporating these prior art ratcheting mechanisms. One significant expense is the inventory expense, which requires that there be sufficient sets of replacement parts to support each model. Another drawback is that as the number of parts which are similar in appearance (but not function) increases, the risk of misassembly or malassembly increases. Such misassembly could cause a component or assembly to disassemble in a patient&#39;s body cavity during surgery. 
     Therefore, what is needed is a simpler mechanism with fewer parts of simpler form. Still further, what is needed is a coupling device design which is configurable to the needs of the user, while minimizing the number of parts the manufacturer must inventory. Still further, what is needed is a coupling device that may be reconfigured for differing actuation without the need for replacing components with new, custom components. What is needed is a means for minimizing the number of parts a reseller or manufacturer must inventory without sacrificing the range of configurations he is able to assemble. 
     SUMMARY OF THE INVENTION 
     A surgical ratchet assembly includes a handle, a drive spindle or shank, a ratcheting mechanism, a locking mechanism and a coupling device. The drive spindle is received within the handle in a rotatable relationship with respect thereto. The ratcheting mechanism is interposed between the handle and the driver. The ratcheting mechanism includes a pawl which can be selectively locked out of engagement with a toothed hub via a reverser. A pair of pawls is preferred. A locking mechanism releasably holds the handle to the ratchet mechanism. Cantilever springs bias the pawl into engagement with the toothed hub. The coupling device couples tool bits to the driver. 
     In a feature of the invention, the coupling device permits actuation of release or engagement of a tool bit in a configurable manner. 
     The object of the invention is to provide a ratchet that is easy to operate and does so reliably. 
     Another object of the invention is to provide a simpler mechanism with fewer parts as no mounting pin is required for the biasing springs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the ratchet handle of the invention. 
         FIG. 2   a  is a perspective view of the ratchet mechanism of the invention, showing the workings therein. 
         FIG. 2  is a perspective view of the cap reverser of the invention. 
         FIG. 3  is an exploded view of the ratchet mechanism  24  of the ratchet handle  10  of the present invention shown in  FIG. 1 . 
         FIG. 4   a  is a perspective view of an alternate spring of the invention. 
         FIG. 4   b  is a perspective view of another alternate spring of the invention. 
         FIG. 4   c  is a perspective view of still another alternate spring of the invention. 
         FIG. 4   d  is a perspective view of still another alternate spring of the invention. 
         FIG. 5   a  is a top view showing the positioning of the biasing means against the pawls of the invention. 
         FIG. 5   b  is a perspective view showing the positioning of the biasing means against the pawls of the invention. 
         FIG. 6  is a longitudinal cross-section of the invention. 
         FIG. 7   a  is a close up of the coupling end of configuration A of the invention. 
         FIG. 7   b  is a close up of the coupling end of configuration B of the invention. 
         FIG. 7   c  is a close up of the coupling end of configuration C of the invention. 
         FIG. 8  is a perspective view of a kit of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     This invention has structural similarities to U.S. Pat. No. 6,817,458 to Gauthier, and WO 2004/096069, PCT/IB2004/001244, the contents of both of which are incorporated herein by reference and relied upon. 
     Referring now to  FIG. 1 , the ratchet handle  10  of the invention is shown, including essentially a handle portion  12 , a coupling end  14 , and a housing assembly  16  in which is disposed a drive spindle  20  having a toothed hub  22 . 
     Referring now to  FIGS. 2   a  and  2   b , a ratchet mechanism  24  is disposed between the toothed hub  22  and the handle  12 , in order to enable a user to selectively torque fasteners (not shown), in a desired direction dependent on the position of a reverser  26 . The reverser  26  is a cap-shaped structure having an internal aperture  30  and position selection holes  32 ,  34  and  36  which pass through a wall  38  of the cap. A crest of a ball detent  40  in the housing  48  enters into such holes  32 ,  34 , or  36  to retain the reverser  26  in the desired position (neutral, locked counterclockwise, free rotating clockwise, and vice-versa). Arcuate cutouts  42  and  44  are located on opposite sides of the aperture  30  and are formed to include corresponding cam surfaces  42   a  and  44   a . These cam surfaces  42   a  and  44   a  are disposed on an arcuate cam structure  42   b  and  44   b  which passes between a centering shoulder  46  and each pawl  50   a  and  50   b  such that, the adjacent pawl  50   a  or  50   b  may be cammed in or out of engagement with teeth  54  on the toothed hub  22 . The pawls  50   a  and  50   b  are held in functional relationship by their generally circular stem  50   c  and  50   d , respectively, in arcuate end surfaces  48   a  and  48   b  of slots  48   c  and  48   d  of a housing  48 , into which the pawls are disposed. Elongated, slender wire springs  52   a  and  52   b  (which can have a circular cross-section, oval cross-section, an uncut rectangular cross-section, even polygonal cross section, as typically results from a rolled or extruded manufacturing process and not cut, flat sheet processing), preferably made of Nickel-Titanium alloy (a.k.a., “nitinol”, from the laboratory that developed it, the Nickel/Titanium/Naval Ordinance Laboratory), a super-elastic, shape memory material, are fixed (using, for example, set screws, or by press fitting, or by a staking operation in the housing, and optionally using a mating nickel-titanium alloy component such as a collet device) in holes  49   a  and  49   b , so as to act as cantilever springs, to urge the pawls  50   a  and  50   b  against the teeth  54  of the hub  22 . Nitinol alloys have the unusual ability to recover a preset shape, even after drastic distortion. Composition is typically 55%-56% Nickel and 44%-45% Titanium, but slight adjustments of this ratio can significantly impact the properties of the material. There are two primary but overlapping categories of Nitinol. “SuperElastic” alloys are characterized by extraordinary kink resistance and flexibility. The Nitinol Wire used in the invention is a super-elastic alloy which can be strained eight to ten times more than ordinary spring steel without permanent deformation. It can be rather severely compressed, bent or otherwise distorted, but returns to its original shape. This impressive “memory” takes advantage of stress-induced martensitic transformation. In other words, a material is super-elastic when, if sufficient stresses are applied, such materials exhibit martensitic activation/transformation (i.e., deform from an austenitic crystal structure to a stress-induced structure postulated to be martensitic in nature), returning thence to the austenitic state when the stress is removed. The alternate crystal structures described give the alloy super-elastic or pseudo-elastic properties. Poisson&#39;s Ratio for nitinol is about 0.3, but this ratio significantly increases up to approximately 0.5 or more when the shape memory alloy is stretched beyond its initial elastic limit. It is at this point that stress-induced martensite is said to occur, i.e., the point beyond which the material is permanently deformed and thus incapable of returning to its initial austenitic shape. Note that although Nickel-Titanium alloys are currently preferred, inexpensive super-elastic steel alloys are now known and of course may be used. The wire used herein has an annealed temper that is straight in shape. A new memory is imparted to the Nitinol wire by restraining the material in exactly the shape required and heating to a temperature above 932° F. (500° C.) for a minimum of five minutes. The shape will be set upon cooling and will exhibit the same flexibility and resistance to deformation as the original wire. And it can be repeatedly retrained to achieve new shapes. 
     Referring now to  FIG. 3 , an exploded view of the ratchet mechanism  24  of the invention includes the housing  48 , the pawls  50   a  and  50   b , the cantilever springs  52   a  and  52   b , a stop pin  56  (which engages an elongated slot  58  of the reverser  26 ), the toothed hub  22 , and the reverser  26 . The stop pin  56  is press fit into the housing  48  so as to fixed therein. 
     Referring to  FIGS. 4   a  to  4   d , suitable wire springs  52   a  and  52   b  may have a circular cross-section  60 , oval cross-section  62 , and uncut rectangular cross-section  64 , even polygonal cross section  66 , as typically results from a rolled or extruded manufacturing process and not cut flat sheet processing which creates stress risers which limit the functional life of the spring. In addition, the length of the spring  52   a , and  52   b  may be processed so that the cross-section varies in bending moment of inertia along its length  52   a ′, then enabling further control of the biasing forces applied to the pawl  50   a  and  50   b . With spring material such as super-elastic Nitinol or super-elastic steels, controlled processing of the spring  52   a  or  52   b  in order to vary and control the bending moment of inertia requires that the spring be formed in an annealed state, prior to heat treating to activate super-elastic properties. Further, where the cross-section is varied in form along the length  52   a ′ of the spring  52   a  or  52   b  in a non-symmetrical manner, then, a portion of the end  52   c  of the spring may be turned up and then against itself, in order to create a feature by which the spring can be held during processing of the non-symmetrical forming of the spring and to enable fixing of the spring in the desired orientation (the orientation that provides the deflection and force characteristics desired). Orientation can be achieved as well via use of a non-round aperture in the housing  48  into which the end  52   c  is fixed. The spring  52   a  or  52   b  may alternatively be deformed at an end  52   d  to create a feature from which an orientation convention can key off of. Of course, the fixing device (e.g., fastener) must also key off of the non-symmetrical end to orient the spring  52   a  or  52   b  properly in the housing  48 . In any case, after processing, the cross-section should have overall width dimensions that are substantially the same across the centerline of the wire. 
     U.S. Pat. No. 5,683,404 to Johnson, entitled “Clamp and Method for its Use”, the content of which is incorporated herein by reference thereto, further discusses shape memory materials that are “pseudo-elastic”, defining these materials to be super-elastic, because of their ability to exhibit super-elastic/pseudo-elastic recovery characteristics at room temperature. 
     Thus, a user is able to select which pawl  50   a  or  50   b  is engaged, thereby selecting the direction in which the ratchet handle  10  freely rotates which respect to the spindle  20  and the direction in which the pawls  50   a  or  50   b  lock the teeth  54  as well as the direction in which the pawls are positioned such that the spindle  20  is free to rotate in the opposite direction. The position of the reverser  26  with respect to the housing assembly  16  is determined by a frictional or interference engagement of a ball-detent  40  in one of the holes  32 ,  34 , or  36 . 
     By adjusting the camming such that in a neutral position, the cam structures  42   b  and  44   b  cam both pawls  50   a  and  50   b  out of engagement, a free-wheeling mode is possible in which the handle is not locked in either direction. Alternatively, adjusting the camming such that both pawls  50   a  and  50   b  are free in a neutral position, ensures that the ratchet mechanism  24  will lock up regardless of the direction in which the handle is torqued with respect to drive spindle  20 . 
     Referring now to  FIG. 3 , an exploded view of the ratchet mechanism  24  of the invention includes the housing  48 , the pawls  50   a  and  50   b , the cantilever springs  52   a  and  52   b , a stop pin  56  (which engages an elongated slot  58  of the reverser  26 ), the toothed hub  22 , and the reverser  26 . The stop pin  56  is press fit into the housing  48  so as to be fixed therein. 
     Referring now to  FIGS. 5   a  and  5   b  the cantilever springs  52   a  and  52   b  bias the pawls  50   a  and  50   b  against the teeth  54  of the hub  22  wherein the extremities  52   e  of such springs are disposed in recesses  50   a ′ and  50   b ′ of the pawls. The form of the spring  52   a  and  52   b  may be curved in a section  52   e ′, in order to minimize wear on the pawls  50   a  and  50   b.    
     The springs  52   a  and  52   b  are secured to the housing  48  at the first end and free to deflect at the second end. Thus, unlike U.S. Pat. No. 6,817,458 to Gauthier, the biasing members are the cantilevered springs  52   a  and  52   b  and not torsional springs. Further, as already mentioned, the cantilever bar of the invention is optionally made of Nitinol, a super-elastic titanium alloy allowing high flexibility and providing a more constant spring force biasing the pawls  50   a  and  50   b  against the teeth  54  of the hub  22 . A constant biasing force provides smoother ratcheting by avoiding drastic variation in biasing force against the teeth  54 , which, if not substantially constant, would cause intermittent dragging of the pawl as it passes from one tooth position to another. 
     In addition, to further prevent the reverser  26  from rotating past the depressions therein (ref. column 6, line 6, Gauthier &#39;458), the stop pin  56 , which is separate from the biasing members  52   a  and  52   b , engages a slot in the cap reverser, similar to Tiede, U.S. Pat. No. 5,613,585 (see column 3, line 25 thereof), the content of which is incorporated herein by reference and relied upon. 
     Referring now to  FIG. 6 , the ratchet handle  10  has a coupling device  200  on a tool bit engaging end  202  of the ratchet handle. Depending on the selection and assembly of washers  204  and retainers  206 , the coupling device  200  may be configured in one of three configurations in which the sleeve  210  may be actuated in a selected direction to initiate a particular mechanical response. The first configuration A (shown in  FIG. 7   a ) is a push-to-actuate, push-to-remove configuration. The second configuration B (shown in  FIG. 7   b ) is a pull-to-actuate, pull-to-remove configuration. The third configuration C (shown in  FIG. 7   c ) is a push or pull actuate or remove configuration. 
     Referring now to  FIG. 7   a , the sleeve  210  is a hollow, cylindrical sleeve which is slidably mounted over the drive spindle  20  along an axis  211 . The drive spindle  20  includes an interior tool tip engaging interface  212  which is generally cylindrical in form, having one or more transversely milled seats  214  passing substantially through the drive spindle from the outside thereof toward the inside, preferably cut using a ball-end endmill in a manner to leave a small shoulder  216  at the interface between the seat and the interior interface  212 , so as to present an obstruction to a ball  220 , and consequently, prevent the ball from passing fully into the interior interface, although permitting enough of the ball to penetrate the interior interface  212  to engage into a recess of a tool bit (not shown) when the coupling device  200  is in a locked position, as shown in  FIG. 7   a . The interior surface  222  of the sleeve  210  includes a ball locking surface  224  interposed between two adjacent ball release recesses  226  and  230 . The sleeve  210  is restrained to slide concentric to the axis  211  via a sliding fit between a forward interior cylindrical surface  232  on the tool bit engaging end  202  and via an interior cylindrical surface  234  of a shouldered spacer  236  serving as a proximal sleeve abutment retained in an abutment recess  236 A by a first retainer  240  seated in a retainer recess  241 . The shoulder spacer  236  holds the first and second spacers  204 A,  204 B and the second and third retainers  206 A,  206 B as well as a return spring  242 , in an assembled, functional relationship. 
     Spaced axially toward the rear of the drive spindle  20 , a distance approximately the diameter of the ball  220  away from the ball seat  214 , a first retainer recess  244  is located. This recess  244  is shallow but wide enough to accommodate the two retainers  206 A,  206 B and spacer  204 A therebetween. An identically formed recess  246  is spaced along the axis still further rearwardly, providing sufficient space therebetween to receive the return spring  242  and to permit sliding movement of the sleeve enough to selectively position either the first ball release recess  226  or the second ball release recess  230  over the ball  220 , depending on the particular configuration, thereby enabling selective release of the ball from a locked position. In this figure, a fixed-to-the-drive spindle configuration of second and third retainers  206 A,  206 B having a first spacer  204 A interposed therebetween, is followed by the return spring  242 , which is followed by the second spacer  204 B which translates with the sleeve  210 , thereby permitting a user to react against an annular actuation flange  208  so as to push-to-engage and a push-to-disengage a tool bit in the recess  212 . 
     Referring now to  FIG. 7   b , configuration B is shown, in which the spacer  204 A, which translates with the sleeve  210 , is followed by the return spring  242  and then by the second and third retainers  206 A,  206 B with the second spacer  204 B interposed therebetween and fixed to the drive spindle  20  in the second recess  246 . This configuration B permits a pull-to-engage, pull-to-disengage configuration. 
     Referring now to  FIG. 7   c , configuration C is shown, in which the second retainer  206 A, fixed in the first recess  244 , is followed by the first spacer  204 A, which acts against the return, spring  242  and translates with the sleeve  210 , which is then followed the second spacer  204 B, and then the third retainer  206 B, which is fixed in the second recess  246 . 
     Referring now to  FIG. 8 , the kit  150  is shown, including the ratchet  10 , tools  130 ,  132 ,  134 ,  136 , a T-bar  138  and a guide pin  139 . The components of the kit  150  are organized in a case  160  having recesses into which the ratchet and the tools may be conveniently stored until use. A selection of surgical fasteners and, optionally, bone plates and other hardware, as well as ancillary tools may be conveniently stored until needed in a particular surgical protocol. 
     In an advantage of the invention, a simpler mechanism with fewer parts of simpler form is provided. 
     In another advantage, a coupling device design is provided which is configurable to the needs of the user, while minimizing the number of parts the manufacturer must inventory. 
     In another advantage, a coupling device is provided which may be reconfigured for differing actuation without the need for replacing components with new, custom or use-specific components. 
     In another advantage, a ratchet handle is provided which minimizes the number of parts a reseller or manufacturer must inventory without sacrificing the range of configurations he is able to assemble. 
     In another advantage of the invention, the cantilever form of the springs  52   a  and  52   b , together with the fact that the springs are made of super-elastic material provide a lasting, reliable activation of the pawls  50   a  and  50   b  and long life to the ratchet. 
     In another advantage, the cantilever form of the springs  52   a  and  52   b  and the use of nickel-titanium in the construction of the cantilever springs enables the springs to exert a nearly constant biasing force biasing the pawls so as to engage them with the hub  22 . 
     In another advantage, the narrow form of the springs  52   a  and  52   b  permit the bulk of the ratchet mechanism to be reduced without sacrificing strength or reliability. 
     In another advantage, the cantilever springs  52   a  and  52   b  enter the housing  48  from the side of the housing, thus permitting maintenance and/or replacement of such springs without having to disassemble the housing assembly  16  (e.g., removing the reverser is not necessary to access the springs). 
     In another advantage, the reverser  26  includes a position in which both pawls  50   a  and  50   b  are in an engaged position, thus locking the ratchet mechanism against free movement in either direction. 
     The object of the invention is to provide a ratchet  10  that is easy to operate and does so reliably. 
     Another object of the invention is to provide a range of ratchet handles with a simpler mechanism with fewer parts to inventory while not sacrificing the resellers ability to configure the actuation of the handle to the preferences of the customer. 
     Another object of the invention is to provide a ratchet in which no mounting pin is required for the biasing springs  52   a  or  52   b.    
     Although the term “driver” may be used herein, this term is meant to encompass taps, guide pins, screwdrivers, reamer drivers and any tool which needs to be fastened and held, even rotated, in a controlled manner. 
     Multiple variations and modifications are possible in the embodiments of the invention described here. Although certain illustrative embodiments of the invention have been shown and described here, a wide range of modifications, changes, and substitutions is contemplated in the foregoing disclosure. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the foregoing description be construed broadly and understood as being given by way of illustration and example only, the spirit and scope of the invention being limited only by the appended claims.