Ratchet handle
A surgical ratchet assembly includes a handle, a driver, a ratcheting mechanism and a locking mechanism. The driver is received within the handle in a rotatable relationship with respect thereto. The ratcheting mechanism is interposed between the handle and the driver. Unlocking of the locking mechanism enables ready disassembly of the assembly for cleaning and component sterilization. A superelastic biasing means is used. The cap reverser further prevents rotation beyond the depressions therein.
This application claims priority to U.S. Provisional patent application, Ser. No. 60/678,245, of the same name, filed on May 5, 2005, the content of which is incorporated herein by reference thereto.
BACKGROUND OF THE INVENTIONThis 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 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. The rotation is controlled such that there is relatively free rotation in one direction and driven, locked rotation in the opposite direction.
Ratcheting mechanisms of this type take various forms, such as those disclosed in U.S. Pat. Nos. 5,613,585; 5,619,891; 5,778,743; 5,873,288; and 5,943,755, the contents of which are incorporated herein by reference thereto and relied upon. In each of these mechanisms, a pair of pawls are disposed within a housing for the tool. The pawls are selectively engageable and disengageable from a toothed gear disposed within the tool housing in order to enable the gear to rotate in a specified direction when adjusting, inserting or removing a fastener However, while tools incorporating ratcheting mechanisms of this type are useful in adjusting, inserting and removing fasteners from various items, the mechanisms also have certain drawbacks. For example, due to the large spacing of the teeth on the gear, ratchet tools must often be rotated more than approximately 10 degrees in order to advance the ratcheting mechanism to the next locking position. In situations where precise movements of a fastener are necessary, the tools incorporating mechanisms of the above-referenced type with gears of this size are not suitable as these mechanisms are very “coarse” and do not allow for precise movements of the fastener.
Further, the prior art ratcheting mechanisms generally include a large number of parts assembled within the housing in order to complete the ratcheting mechanism, the complexity increasing the time and expense necessary for manufacturing tools incorporating these prior art ratcheting mechanisms.
Therefore, what is needed is a simpler mechanism with fewer parts of simpler form.
SUMMARY OF THE INVENTIONA surgical ratchet assembly includes a handle, a driver, a ratcheting mechanism and a locking mechanism. The driver 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.
In a feature of the invention, the cantilever springs are made of super-elastic material, thereby providing lasting, reliable activation of the pawls and long life to the ratchet.
In another feature, the cantilever form and the use of nickel-titanium in the construction of the cantilever springs enables the spring to exert a nearly constant biasing force biasing the pawl into engagement with the hub.
In another feature, the narrow form of the springs permit the bulk of the ratchet mechanism to be reduced without sacrificing strength or reliability.
In another feature, the cantilever springs enter the assembly from the side of the housing, thus permitting maintenance and/or replacement without having to disassemble the housing assembly (e.g., removing the reverser is not necessary to access the springs).
In another feature, the reverser includes a position in which both pawls 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 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
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
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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 50a or 50b 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 50a or 50b lock the teeth 54 as well as the direction in which the pawls are positioned such that the spindle 20 is free to rotation 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.
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The springs 52a and 52b 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 52a and 52b 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 50a and 50b 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 '458), the stop pin 56, which is separate from the biasing members 52a and 52b, 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.
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In an advantage of the invention, the cantilever form of the springs 52a and 52b, together with the fact that the springs are made of super-elastic material provide a lasting, reliable activation of the pawls 50a and 50b and long life to the ratchet.
In another advantage, the cantilever form of the springs 52a and 52b 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 52a and 52b permit the bulk of the ratchet mechanism to be reduced without sacrificing strength or reliability.
In another advantage, the cantilever springs 52a and 52b 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 50a and 50b 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 simpler mechanism with fewer parts as no mounting pin is required for the biasing springs 52a or 52b.
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.
Claims
1. A ratcheting tool having a ratcheting mechanism comprising:
- (a) a housing;
- (b) at least one pawl pivotally disposed in the housing; and
- (c) at least one cantilever wire spring engaged with the at least one pawl to bias the pawl into engagement with corresponding ratchet teeth, wherein the spring enters through an aperture in a side of the housing.
2. The ratcheting tool of claim 1, wherein the spring is fixed via a fastening device in the side of the housing.
3. The ratcheting tool of claim 1, wherein the spring is fixed via a staking operation in the side of the housing.
4. The ratcheting tool of claim 1, wherein the spring is slender and substantially straight.
5. The ratcheting tool of claim 1, wherein the spring is made of a super-elastic material.
6. The ratcheting tool of claim 1, wherein the spring is made of a super-elastic material.
7. The ratcheting tool of claim 2, wherein the spring is made of a super-elastic material.
8. The ratcheting tool of claim 3, wherein the spring is made of a super-elastic material.
9. The ratcheting tool of claim 4, wherein the spring is made of a super-elastic material.
10. The ratcheting tool of claim 5, wherein the spring is made of Nitinol.
11. The ratcheting tool of claim 1, further including a reverser disposed in a structure to rotate with respect to the housing.
12. The ratcheting tool of claim 11, wherein the reverser is adapted to selectively move the at least one pawl into and out of engagement with teeth on a toothed hub to select between positive torque throughput of the ratchet handle and free-rotation.
13. The ratcheting tool of claim 11, wherein the reverser is adapted to selectively move the at least one pawl into and out of engagement with the ratchet teeth to enable the selection between positive torque throughput of the ratchet handle and free-wheeling.
14. The ratcheting tool of claim 13, wherein the ratcheting tool includes at least two opposed pawls against which the reverser reacts to selectively move one pawl out of engagement with the teeth while the other is permitted to engage the teeth, thereby enabling reversing of the direction of ratcheting and positive throughput.
15. The ratcheting tool of claim 11, in which the housing including at least one slot including a generally arcuate end circumscribing an angle of greater than 180 degrees.
16. The ratcheting tool of claim 15, wherein at least one pawl is disposed in the at least one slot, the pawl including a generally circular stem at one end that is rotatably engaged within the arcuate end of the slot.
17. The ratcheting tool of claim 16, wherein the reverser includes a at least one recess aligned with and disposed at least partially above the at least one slot in the housing and selectively engageable with the at least one pawl, and further, wherein a stop pin, fixed to the housing, engages a slot in the reverser to limit the rotational movement of the reverser between two positions.
18. A ratcheting tool having a ratcheting mechanism comprising:
- (a) a housing;
- (b) at least one pawl pivotally disposed in the housing; and
- (c) at least one cantilever wire spring engaged with the at least one pawl to bias the pawl into engagement with corresponding ratchet teeth; wherein the housing includes a pair of slots, each slot including a generally arcuate end circumscribing an angle of greater than 180 degrees; wherein a pair of pawls are disposed in the pair of slots, each pawl including a generally circular stem at one end that is rotatably engaged within the arcuate end of the slot; wherein the ratcheting tool includes a reverser disposed in a structure to rotate with respect to the housing, the reverser being adapted to selectively move the at least one pawl into and out of engagement with teeth on a toothed hub to select between positive torque throughput of the ratchet handle and free-rotation and wherein the reverser includes at least one recesse aligned with and disposed at least partially above the at least one slot in the housing and selectively engageable with the at least one pawl, and further, wherein a stop pin, fixed to the housing, engages a slot in the reverser to limit the rotational movement of the reverser between two positions.
19. A kit for surgical use, the kit including a surgical ratchet including a ratcheting mechanism a housing, at least one pawl pivotally disposed in the housing; and at least one cantilever wire spring made of super-elastic material and engaged with the at least one pawl to bias the pawl into engagement with corresponding ratchet teeth, tools for use with the ratchet, a selection of surgical fasteners and a case having recesses into which the ratchet and the tools may be conveniently stored until use.
Type: Application
Filed: Oct 5, 2005
Publication Date: Nov 9, 2006
Inventors: Patrick White (West Chester, PA), Jeffrey Bennet (Pottstown, PA), Michael Doran (Paoli, PA), Robert Young (Loganville, GA)
Application Number: 11/244,301
International Classification: B25B 13/46 (20060101);