Abstract:
A torque apparatus for the installation and removal of threaded connecting device that employs a plurality of leaf spring elements engaging a plurality of asymmetrical drive teeth sides to establish preset torque values in a hermetically sealed configuration or a variable range of preset torque values in a second configuration. The preset torque values can be readily changed in the second configuration by employing different quantities of leaf springs, differing leaf spring designs, or varying the geometry of the rotor drive teeth. The leaf spring to rotor drive teeth interface provides a slip mechanism to prevent over-torquing when torque values for the installation of a threaded connecting type device is exceeded. While both torque wrench configurations are sterilizable, the torque wrench that is capable of full disassembly for sterilization and use thereafter in a sterilized environment, is reconfigurable for different torque applications without calibration. The wrench can be primarily constructed as disposable device.

Description:
BACKGROUND 
     1. Technical Field 
     The resent disclosure relates to controlling the amount of torque applied to a threaded connection. More particularly, the present disclosure relates to an apparatus for applying a controlled amount of torque to either install or remove a threaded connection working member. 
     2. Description of Related Art 
     Torque wrenches are well known devices which most commonly use one or more elastic bending rods as in U.S. Pat. No. 5,734,113 to Vogt et al. (“Vogt et al.”) or an axial spring device as in U.S. Pat. No. 5,859,371 to Hsieh (“Hsieh”) and U.S. Pat. No. 5,911,801 to Fravalo et al. (“Fravalo et al.”) as the primary source of their torque sensing mechanism. These torque wrenches use complex mechanisms that frequently employ one or more helical springs, roller bearings, an rod devices enclosed within their handle cavity. For example, Fravalo teaches a wrench head that pivots inside a hollow cavity and interfaces with a plunger rod type device that employs at least one rolling body to minimize friction. This mechanism then interfaces with an axially coiled spring. These internal mechanisms are too complex to support disassembly for ease of sterilization and are too expensive to use as a disposable torque wrench device. 
     Some patents directly address some degree of dismantling or removing and replacing internal components such as U.S. Pat. No. 4,249,435 to Villeneuve et al. (“Villeneuve et al.”) and U.S. Pat. No. 5,734,113 to Vogt et al. (“Vogt et al.”). These torque devices are also internally complex and cannot be cost effectively dismantled, sterilized, and then reassembled for use in sterile environment. 
     Another aspect of torque wrench technology involves a mechanism to preclude over torquing through a slip mechanism within the torque wrench. One torque wrench that has a leaf spring slip mechanism is U.S. Pat. No. 5,224,403 to Rueb (“Rueb”). Rueb teaches two basic embodiments of cantilevered beam leaf spring type torque wrench mechanisms that slip when the torque limit is exceeded. 
     In the first embodiment, the leaf spring acts as a cantilever beam that extends from the handle to perpendicularly engage a single symmetrical vertical gear tooth in the wrench head. Torque values are adjusted on the handle by varying the effective length of the cantilevered beam. In a similar second embodiment, Rueb discloses two perpendicular springs located within the wrench head that engage gear teeth a with complex double tooth shape. The perpendicular springs that engage the complex double tooth gears are held in place by two retaining shoulders of different height that create a shorter stiffer beam with greater resistive force in the counterclockwise direction than in the clockwise direction. Each complex double tooth of the gear has a single tooth side, where only the long tooth is engaged, and a double tooth side, where first the short and then the long tooth is engaged. The single tooth and double tooth sides are symmetrically sloped. Maximum clockwise torque is achieved as the longer tooth is engaged on the single tooth side of the complex double tooth gear by the perpendicular leaf spring and the perpendicular leaf spring is forced past the resisting counter force of the spring retaining shoulder. The lower clockwise supporting spring retaining shoulder creates a cantilever beam with a longer, less resistive counter force. 
     This second embodiment removes a threaded member in the counterclockwise direction without adjustments using a combination of the double tooth form and the shock force imparted by the spring as it forced past the first shorter tooth and then impacts upon the second longer tooth. In addition, the longer counterclockwise retaining shoulder support provides a shorter cantilevered spring that provides greater resistive force than in the clockwise direction. 
     The second embodiment of Reub is distinctly limited by its lack of ability to adjust for different torque values and its internal complexity which precludes it from being disassembled, sterilized, and reassembled for use in a sterile environment. As a result, this and other current torque wrench designs require the surgical instrument to be removed from the sterile environment, their working member removed and replaced with the proper torque, and then the surgical instrument must be resterilized. Torque wrenches that have mechanisms such as those above and are used in medical applications are typically not used in a sterile environment. 
     Accordingly, there is a need for improved apparatus for applying a controlled amount of torque that can be sterilized using readily available sterilization equipment. It is desirable that the apparatus be simple in construction, easy to disassemble and reassemble, and that it does not require calibration upon reassembly. It is desirable to provide a torquing apparatus that is so inexpensive that it can be disposable. It is further desirable that the torquing apparatus have the potential to apply different torques for different threaded member applications and require no adjustments for the installation or removal of a specific threaded connection. 
     SUMMARY 
     A torque apparatus is provided that employs a plurality of leaf spring elements engaging a plurality of asymmetrical drive teeth sides to establish a range of preset torque values for the installation and removal of threaded connecting devices. The preset torque values can be readily changed by employing different quantities of leaf springs, differing leaf spring designs, or varying the geometry of the rotor drive teeth. The leaf spring to rotor drive teeth interface provides a slip mechanism to prevent over-torquing when torque values for either the installation or removal of a threaded connecting type device are exceeded. The wrench head may be hermetically sealed in its preferred configuration, or in an alternative configuration capable of full disassembly. Both configurations can be readily sterilized using an autoclave or similar sterilization methods. The second configuration adds the advantage that the apparatus can be reconfigured for different torque applications without calibration within a sterilized environment. The wrench can also be employed as a disposable device. 
     The invention, together with attendant advantages, will be best understood through by the reference to the following detailed description of the invention when used in conjunction with the figures below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an enlarged exploded perspective view of one configuration of the torque apparatus; 
     FIG. 2A is a perspective view of the handle and head of the torque apparatus; 
     FIG. 2B is a perspective view of an alternative handle configuration for the torque apparatus; 
     FIG. 2C is a view of an additional handle configuration for the torque apparatus; 
     FIG. 3A is an enlarged top view of a leaf spring section; 
     FIG. 3B is an enlarged perspective view of a leaf spring section; 
     FIG. 4A is an enlarged perspective view of the rotor showing the radial drive teeth; 
     FIG. 4B is an enlarged sectional view of a portion of the rotor showing the asymmetrical sides of the drive teeth; 
     FIG. 5 is an enlarged perspective view of one configuration of a hex drive insert; 
     FIG. 6 is an enlarged top view of the head of a torque wrench with a pair of leaf springs, rotor, and drive insert installed showing the engagement between the leaf springs and the rotor drive teeth; 
     FIG. 7 is a perspective view of the holding device for applying a controlled amount of torque; and 
     FIG. 8 is a perspective view of the torque apparatus kit which includes a apparatus, a plurality of leaf springs, one or more rotors, and numerous drive inserts for common connector interfaces. 
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings in detail, and initially to FIG. 1, torque wrench  100  includes a handle  110 , a head  112 , at least one leaf spring  120 , at least one rotor  130 , a plurality of hex inserts  140 , and a cap  150 . When cap  150  is in position, it holds rotor  130  and hex insert  140  in place within head  112 . Cap  150  can be fixedly connected to head  112  using ultrasonic welding, or similar techniques, to form a hermitic seal, removably attached, or be an integral part of head  112 . Thus, torque wrench  100  is configured to be easily sterilized as a hermitically sealed assembly or disassembled and sterilized using widely available sterilization techniques. Torque wrench  100  is configurable as either a disposable or reusable instrument. 
     Referring now to FIG. 2A, torque wrench  100  has a handle  110  on a first end, and a head  112  on an opposing second end. Handle  110  contains a grip enhancing means  111  that includes ergonomic enhancements such as knurling, scalloping, or undulations that aid gripping. Head  112  has side walls  113  that define internal cavity  114 . Internal cavity  114  in head  112  has a hexagonal shape in this configuration with two stops  116  on the inside of side walls  113 . Handle  110  and head  112  are preferably made of plastic although other medical grade materials are also envisaged such as, e.g. stainless steel, titanium, etc. 
     In FIG. 2B an alternative configuration is shown which integrates handle  110  into cap  150 . In this configuration, cap  150  contains a grip enhancing means  111 , such as knurling, scalloping, or radially extending undulations, and would enable the user to apply sufficient torque in the lower ranges of torque values. 
     In FIG. 2C an additional configuration is shown which integrates handle  110  into head  112 . In this configuration, head  112  contains a grip enhancing means  111 , such as knurling, scalloping, or radially extending undulations, and would similarly enable the user to apply sufficient torque in the lower ranges of torque values. This configuration of torque apparatus  100  could also be extended longitudinally to take the form of a screwdriver-torque wrench. 
     Referring now to FIG. 3A, angular leaf spring  120  has a plurality of novel cantilevered beam elements  122  that are sharply angled from a radial azimuth and are positioned to provide the torque limiting component of the design. Each beam element  122  has a first section  124  and a second section  126 , which is defined by a second bend in the beam element  122 . Second bend section  126  facilitates sustaining the proper degree of physical interface at all times. Second section  126  has end with an inside end corner  128  that is coined with a radius profile that is designed to minimize frictional forces. 
     In FIG. 3B, leaf spring  120  is shown with angled cantilevered beam elements  122 . The number of leaf spring elements  122  per leaf spring  120  can vary with the design application. Leaf spring  120  is preferably made from a sheet metal stamping. 
     Referring now to FIG. 4A, the rotor  130  in this configuration has twelve simple radially extending single toothed drive teeth  131 . The quantity of drive teeth  131  can vary with the design application. Each drive tooth  131  has a clockwise ramp side  132  and a counterclockwise flat side  134 . The top of rotor  130  defines a hexagonal cavity  136  with sidewalls  138 . Rotor  130  is preferably made of medical grade plastic materials. 
     In FIG. 4B the asymmetrical nature of the sides of drive teeth  131  of rotor  130  is illustrated. In this configuration, clockwise ramp sides  132  are gradually sloped and counterclockwise flat sides  134  are steeply angled. Additional asymmetrical configurations of sides  132  and  134  can be used to vary the range of torque values of this mechanism. Similarly, the rotor  130  design can be reversed to have a flat side  134  in the clockwise direction and a ramp side  132  in the counterclockwise direction. 
     Referring now to FIG. 5, drive insert  140  functions as a drive mechanism interface for threaded connecting devices. In FIG. 5, a {fraction (9/32)} inch hex drive insert  140  is shown that is specifically intended to interface with the CUSA EXcel 23 kHz product manufactured by Valleylab Inc. The drive insert  140  hex interface can also be configured for a {fraction (7/32)} inch hex drive  140  to interface with CUSA EXcel 36 kHz handpieces manufactured by Valleylab Inc. Additional drive insert  140  configurations could include interfaces for other hexagonal sizes as well as hex key, slot or phillips head screw driver, or any similar working member or attachment type device. All the drive inserts  140 , such as the {fraction (7/32)} drive insert  140  and {fraction (9/32)} insert have the same external hexagonal sidewall  144  dimensions and shoulder  146  and are thus interchangeable. Drive insert  140  is preferably made of metal, and in the removable cap configuration, is specifically designed to be easily changed in a sterile environment. 
     Referring now to FIG. 6, torque wrench  100  is shown partially assembled. In this illustration, two leaf springs  120  are installed in head  112  between two stops  116  in cavity  114 . Torque wrench  100  can operate with one or more leaf springs  120  to establish a different set of torque vlaues at preset intervals. Torque values are preset in the hermetically sealed configuration and, in addition, torque wrench  100  can also be configured to be easily disassembled in so that leaf springs  120  may be easily added to or removed from head  112  in a sterile environment. Rotor  130  is positioned within head  112  to engage leaf spring elements  122 . Hex drive insert  140  can be a separate assembly and installed within rotor  130  or be configured as an integral part of the rotor  130 . As installed within rotor  130  as a separate assembly, the drive insert  140  is inserted into hexagonal cavity  136 . Sidewalls  144  of rotor  140  then interface directly with the sidewalls  138  of hexagonal cavity  136 . The materials in the combined configuration of rotor  130  and drive insert  140  can include medical grade plastic or metal for both subassemblies or combinations of different materials bonded together. Drive insert  140  has a shoulder  146  which rides between the head  112  and the rotor  130 . The drive insert  140  is designed to be removable and replaceable in a sterile environment and is retained inside rotor  130  without a press fit or glue. 
     In operation, when the operator turns the torque wrench  100  clockwise to tighten a working member, the bias of each leaf spring element  122  turns rotor drive teeth  131 , drive insert  140 , and thus the threaded connecting device with the user&#39;s applied torque until the torque limit is exceeded. In this process, ramp sides  132  engage a plurality of inside coined edges  128  of second sections  126  of beam elements  122 . The coining of inside edge  128  creates an almost frictionless interface between the plastic rotor  130  and metal beam element  122 . With friction reduced, the user then only needs to increase the applied torque to ramp side  132  to deflect and overcome the opposing counter force from the spring bias of the at least one angled leaf spring cantilever beam element  122 . The opposing counter force from each cantilevered beam element  122  increases as it is deflected and applied clockwise torque approaches its maximum as the inside edge tip  128  of second section  126  is forced up ramp side  132 . The applied torque peaks just prior to leaf spring element  122  releasing past ramp side  132 . The slippage of each leaf spring element  122  up and over ramp side  132  of rotor drive teeth  131  defines a torque controlling mechanism that limits the applied torque to rotor drive teeth  131  and drive insert  140 . With the installation of one leaf spring  120  in head  112 , torque wrench  100  achieves approximately 30 in-lbs in the clockwise direction before releasing for the CUSA EXcel 36 kHz instrument and, using two leaf springs, at least about 60 in-lbs for the CUSA EXcel 23 kHz instrument before leasing. 
     When an operator removes a working member with a counterclockwise rotation, a plurality of flat sides  134  of rotor  130  form flush interfaces with a plurality of second beam sections  126  of cantilevered beam elements  122 . At this point, beam elements  122  are placed primarily in compression and secondarily in a transverse deflection. The working member removal torque necessary for the flat side  134  to compress the second beam  126  in the counterclockwise direction is at least about 1.5 times that of the installation torque of the maximum torque achieved by ramp side  132  to second beam  126  interface just prior to releasing. When the maximum torque is exceeded, the torque controlling mechanism limits the applied torque to the rotor drive teeth  131  and drive insert  140  by forcing the release or slippage of leaf spring elements  122  past the flat side  134  of rotor drive teeth  131 . Wrench  100  is configured to provide an audible click that also has a distinct tactile indiction in the wrench with the rotation of every drive tooth  131  or approximately every 30 degrees of rotation in this application. Rotor  130  is preferably made of a plastic type material that will minimize frictional forces between the metal beam element  122  and ramp side  132  and flat side  134  of drive teeth  131 . 
     Torque wrench subassemblies such as the handle  110 , head  112 , leaf springs  120 , rotor  130 , drive insert  140 , and cap  150  (see FIG. 1) may be combined to form a reduced total number of subassemblies. For example, rotor  130  and drive insert  140  may be combined into a single subassembly, cap  150  can include handle  110 , and in a similar manner, one or more leaf springs  120  may be permanently installed into head  112 . 
     Referring now to FIG. 7, a holding device  160  is provided in this embodiment to hold CUSA EXcel product line 23 kHz and 36 kHz surgical instrument handpieces, but could be configured to hold any number of devices. The holding device  160  is intended to be reusable and is used in conjunction with the torque wrench while torquing working members or tips onto or removing them from CUSA handpieces. Holding device  160  has at least one pair of gripping devices  162  for holding the metal portion of the instrument&#39;s handpiece and supports the overall body of the instrument. This reduces the risk of damage to the more fragile plastic areas of the handpiece. In addition, holding device  160  provides the user with a hand hold  164  that provides a mechanical advantage during the torquing process. The design of holding device  160  provides a rapidly cooling geometry which expedites cooling upon removal from an autoclave. 
     Referring now to FIG. 8, a torque apparatus kit  170  which includes components such as one or more torque wrenches  100 , a set of leaf springs  120 , one or more rotors  130 , and a set of drive inserts  140  that provide flexibility of use in applications such as hex wrench, hex key, screwdriver, etc., and a cap  150 . 
     A set of leaf springs  120  provides a range of torque values. Using one configuration of the current torque wrench  100  that can employ up to two leaf springs, a first pair of leaf springs  120  is mounted in the kit with a given torque value next to a second pair of leaf springs  120  with a higher torque value. Each leaf spring  120  would be labeled with its torque limit values in both directions of rotation when used individually, its increased torque values when used in combination with its paired leaf spring  120 , as well as its relative point of retention within the kit being labeled with its individual and paired torque values. In a similar manner, a set of drive inserts  140  provides torque wrench  100  with a range of inserts for application with different types of threaded connecting devices. 
     Although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings, it is to be understood that the disclosure is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the disclosure. All such changes and modifications are intended to be included within the scope of the disclosure.