Abstract:
The present invention is directed to a keyless shoe lock assembly for a reciprocating saw. The keyless shoe lock assembly is capable of engaging and releasing a shoe bracket for the positional adjustment of a shoe relative to a blade clamp of the reciprocating saw. The keyless shoe lock assembly includes a shoe bracket for positional adjustment relative to a lock plate, a pin for alternately engaging and releasing the shoe bracket, and a lever connected to the pin for the rotation therof. The keyless shoe lock assembly may be used to alternately engage and release a shoe bracket without additional hardware.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation of U.S. patent application Ser. No. 10/685,351 filed on Oct. 14, 2003, which claims benefit under 35 USC § 119(e) of U.S. provisional patent application Ser. No. 60/417,946 filed on Oct. 11, 2002 and U.S. provisional patent application Ser. No. 60/453,815 filed on Mar. 11, 2003. The disclosure of the above applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to the field of reciprocating saws, and particularly to a keyless shoe assembly for reciprocating saws wherein the keyless shoe assembly employs a keyless lock allowing positional adjustments to be made to the shoe assembly without the need for hand tools.  
       BACKGROUND OF THE INVENTION  
       [0003]     Reciprocating saws are well known in the art. The straight back and forth, or reciprocal, action of its blade, characterizes a reciprocating saw. Some reciprocating saws also have the ability to assume an orbital blade motion, characterized by a slightly circular motion as the blade moves back and forth. Reciprocating saws include a blade clamp suitable for securing the blade to the saw, and a brace, commonly referred to as a shoe, used to brace the reciprocating saw against a work piece during a cut. The shoe is generally located some adjustable distance from the blade clamp. The adjustable nature of the shoe serves two purposes: it allows a user to control the depth of a cut, and it makes it possible to evenly distribute wear on the blade.  FIG. 1  illustrates a typical reciprocating saw  50 , including a saw blade  54  and a shoe  56  connected to a saw  52 .  
         [0004]     While using the reciprocating saw, it is frequently desirable to adjust the distance of the shoe from the blade clamp. For instance, a user might switch from making a cut in a hard to reach place, requiring a longer length of blade, to making a plunge cut into a material at a shallow depth, requiring a much shorter blade length. In addition, frequently adjusting the distance of the shoe from the blade clamp has the benefit of shifting the range of contact of the teeth as the blade reciprocates; thereby lengthening the life of a typical reciprocating saw blade.  
         [0005]     Adjustment of the distance from the shoe to the blade clamp may be accomplished through the positional adjustment of a shoe bracket, to which the shoe is attached, and which is capable of movement parallel to the blade of the saw. In many typical applications, a hand tool such as a wrench, screwdriver, or other suitable device may be used to alternately tighten and loosen a fastener securing the shoe bracket, allowing adjustment of its position, and consequently the position of the shoe. However, the conventional use of a wrench, screwdriver, or some other hand tool to adjust the position of the shoe bracket may not be desirable. In addition to the added time expended in locating the hand tool, if the adjustment must be made at a remote location, the absence of such a tool may effectively prevent adjustment of the shoe bracket. While it is possible to add an integrated wrench assembly to a reciprocating saw for tightening and loosening the fastener securing the shoe bracket, the wrenching action required does not correspond to the normal gripping action of a typical user.  
         [0006]     In the prior art, this limitation has typically been overcome by providing a keyless shoe lock, consisting essentially of a shoe bracket including a plurality of notches or grooves, and a pin suitable for engaging the shoe bracket when seated in a notch or groove. The pin is generally attached to a lever, the action of which corresponds with the normal gripping action of a typical user. But this method also presents limitations. First of all, the pin must be of a certain diameter to meet the necessary strength requirements for a tool that vibrates as rapidly and as strongly as a reciprocating saw does—especially when cutting through particularly unwieldy material. Second, the notches or grooves in the shoe bracket must be a certain minimum distance apart to provide enough material contact with the pin to ensure the shoe bracket does not slip during operation.  
         [0007]     Thus, the combination of two factors, namely the diameter of the pin and the spacing of the notches or grooves in the shoe bracket, severely limits the number of discrete positions the shoe bracket and shoe are capable of assuming. As previously noted, one of the reasons that it is desirable to adjust the shoe bracket and shoe is that shifting the range of contact of the blade lengthens the life of a saw blade. As the teeth may be much smaller than the distance between discrete positions attainable by the shoe as taught by the prior art, the use of a pin and a shoe bracket including notches or grooves may have served only to shift the range of contact between sets of teeth on the reciprocating saw blade.  
         [0008]     Consequently, it would be desirable to provide a keyless shoe lock for a reciprocating saw, enabling the positional adjustment of a shoe in small increments.  
       SUMMARY OF THE INVENTION  
       [0009]     Accordingly, the present invention is directed to a keyless shoe lock assembly for a reciprocating saw, capable of engaging and releasing a shoe bracket, for the positional adjustment of a shoe relative to a blade clamp of the reciprocating saw. The keyless shoe lock assembly may include a shoe bracket capable of positional adjustment relative to a lock plate, a pin suitable for alternately engaging the shoe bracket against and releasing it from the lock plate, and a lever connected to the pin suitable for the rotation thereof. In exemplary embodiments of the present invention, a keyless shoe lock may be used to alternately engage and release a shoe bracket by a person of normal physical strength without the use of additional hardware.  
         [0010]     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:  
         [0012]      FIG. 1  is an isometric view illustrating an exemplary reciprocating saw;  
         [0013]      FIG. 2  is an isometric view illustrating a keyless shoe lock assembly for a reciprocating saw, capable of alternately engaging and releasing a shoe bracket in accordance with an exemplary embodiment of the present invention;  
         [0014]      FIG. 3  is an isometric view illustrating a shoe bracket for a keyless shoe lock assembly in accordance with an exemplary embodiment of the present invention;  
         [0015]      FIG. 4  is an isometric view illustrating a lock plate for a keyless shoe lock assembly in accordance with an exemplary embodiment of the present invention;  
         [0016]      FIG. 5  is an obverse isometric view illustrating the shoe bracket shown in  FIG. 3 ;  
         [0017]      FIG. 6  is a partial cross-sectional side elevational view of the keyless shoe lock assembly shown in  FIG. 2 , illustrating a lever action for disengaging the shoe bracket from a lock plate in accordance with an exemplary embodiment of the present invention;  
         [0018]      FIG. 7  is a partial cross-sectional side elevational view of the keyless shoe lock assembly shown in  FIG. 2 , wherein the shoe bracket has been disengaged from the lock plate by the lever action shown in  FIG. 6 ;  
         [0019]      FIG. 8  is a partial isometric view of the keyless shoe lock assembly shown in  FIG. 2 , wherein the shoe bracket is disengaged from the lock plate; and  
         [0020]      FIG. 9  is a partial isometric view of the keyless shoe lock assembly shown in  FIG. 2 , wherein the shoe bracket is engaged against the lock plate. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.  
         [0022]     Referring generally now to  FIGS. 2 through 9 , a reciprocating saw having a keyless shoe assembly in accordance with an exemplary embodiment of the present invention is described. The keyless shoe assembly includes a keyless lock that allows a user of a reciprocating saw to make positional adjustments to the shoe without the need for hand tools. Shoe adjustability allows for longer life of a reciprocating saw blade due to a shift in the range of contact of the teeth as the blade reciprocates. Preferably, the shoe bracket (that part to which the shoe is attached which is clamped to the tool) is attached as solidly as possible to the reciprocating saw in order to eliminate the amount of “play” in the shoe as the user cuts with the saw.  
         [0023]     As shown in  FIGS. 2 through 9 , a keyless shoe lock assembly  100  for a reciprocating saw in accordance with an exemplary embodiment of the present invention includes a shoe  102  pivotally connected to a shoe bracket  104  with a fastener  106 . Fastener  106  may comprise a pin, a rivet, and the like as contemplated by one of ordinary skill in the art. The shoe bracket  104  is enmeshed with a lock plate  108  by a pin  110 . The pin  110  may have a variety of shapes and profiles suitable for engaging the shoe bracket  104 , including but not limited to an eccentric shape, a cam shape, and a circular shape including a substantially flat portion. The lock plate  108  and pin  110  are connected to a housing of the reciprocating saw  120 , the pin  110  being rotationally connected to the housing of the reciprocating saw  120 . In an exemplary embodiment of the present invention, the pin  110  is fixedly connected to a lever  112 , which pivots about an axis of the pin  110 . It should be appreciated that the interface between the shoe  102 , the shoe bracket  104 , and fastener  106 , may include a spring or some other suitable means for stabilizing the shoe  102  relative to the shoe bracket  104 . Also, it should be appreciated that the shoe  102  and fastener  106 , or the shoe bracket  104  and fastener  106 , or the lock plate  108  and the housing of the reciprocating saw  120 , or the pin  110  and the lever  112 , may be of one-piece construction without departing from the scope and spirit of the present invention.  
         [0024]     In the embodiment shown, the pin  110  allows the shoe bracket  104  to slide in from the front of the tool when in the “unlocked” position. When rotated approximately  90  degrees, the pin  110  pushes the shoe bracket  104  down against the lock plate  108 . Both the lock plate  108  and the shoe bracket  104  comprise “teeth” which mesh when the shoe bracket  104  and the lock plate  108  are pressed against each other. These teeth hold the shoe bracket  104  in position while the reciprocating saw is in use. It should be appreciated that while the teeth of the embodiment shown comprise a plurality of semicircular ridges; one of ordinary skill in the art may also contemplate a plurality of semicircular ridges and correspondingly shaped grooves, a plurality of interference protrusions, a friction interface, and the like, for securing the shoe bracket against the lock plate without departing from the scope and spirit of the present invention.  
         [0025]     Referring generally to  FIG. 2 , in a further exemplary embodiment of the present invention, the lever  112  may be covered by a molded or co-molded plastic part  122  for purposes including comfort, locking, and UL listing. In another exemplary embodiment of the present invention, the lever including the molded or co-molded plastic part  122  may automatically lock against a boot covering a casting  124  when a user grasps the boot covering the casting  124  and the lever  112  in the course of normal gripping action. This locking action may be accomplished through the use of an interference protrusion engaged when the pin  110  is in the locked position and engages the shoe bracket  104 . This locking action may also be accomplished through the use of a plurality of teeth, a plurality of teeth and grooves, a friction interface, and the like, as contemplated by one of ordinary skill in the art.  
         [0026]     Referring generally to  FIGS. 3 and 4 , a shoe bracket  104  and a lock plate  108  include series of teeth  114  and  118  respectively. Teeth  114  and  118  may be spaced apart as needed to provide sufficient range and an adequate number of discrete steps for the shoe bracket  104  to assume, as dictated by the size of the reciprocal saw and its possible or intended applications. Preferably, the teeth  114  of the shoe bracket  104  are positioned on either side of the slot, on the underside of the shoe bracket  104  and are spaced from each other so as to allow debris to fall from between them. As noted, the lock plate  108 , like the shoe bracket  104 , also comprises teeth  118 . However, in the exemplary embodiment shown, the spacing D 2  between the teeth  118  is half of the spacing D 1  on the shoe bracket  104  allowing the user to lock the two pieces securely together regardless of their relative position. It has been determined that if the shoe bracket  104  and lock plate  108  are provided with the same tooth spacing D 1  and D 2 , one part is allowed to move relative to the other (a total distance of the space between each tooth). However, by doubling the spacing on one part from what is on the other, this problem is reduced or eliminated, while still allowing the user to lock in all positions, and still eliminating structure that would create a debris trap.  
         [0027]     Referring generally to  FIG. 5 , the “anti-lock protrusion” features  126  on the ends of the legs of the shoe bracket  104  prevent the user from turning the pin  110  while the shoe bracket  104  is in a position where it is undesirable to lock.  
         [0028]     Referring generally to  FIGS. 6 through 9 , a meshing of teeth  114  and  118  locks the shoe bracket  104  in place relative to the lock plate  108  and the housing of the reciprocating saw  120 , as seen in  FIG. 6 . When the lever  112  is rotated  116  about the axis of the pin  110 , in the exemplary embodiment of the present invention shown, the profile of the pin  110  relative to the shoe bracket  104  changes, allowing the shoe bracket  104  to slide relative to a lock plate  108 , as seen in  FIG. 7 . It should be noted that it is the meshing teeth  114  and  118  that actually lock the shoe bracket  104  from moving in and out of position. The pin  110  serves to securely press the shoe bracket  104  downward against the lock plate  108 , enabling the meshing of teeth  114  and  118 . Thus, the pin  110  prevents movement of the shoe bracket  104  in a direction perpendicular to a plane of the lock plate  108 , while the lock plate  108  prevents movement of the shoe bracket  104  in a direction parallel to the plane of the lock plate  108 .  
         [0029]     It is believed that the keyless shoe lock assembly of the present invention and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof, it is the intention of the following claims to encompass and include such changes.