Abstract:
A reciprocating saw having a housing, a reciprocating shaft unrotatably connected to a blade, a rear handle and a forward handle, the forward handle being rotatably mounted to the housing near the blade and capable of sliding relative to the reciprocating shaft, but incapable of rotating relative to the reciprocating shaft. The forward handle comprises at least one hole, the reciprocating saw further includes a button connected to a locking element for engaging or disengaging with the at least one hole. The reciprocating saw is easy and comfortable to operate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. 119 to Chinese Patent Application No. 200820033942.X filed Mar. 28, 2008, and Chinese Patent Application No. 200820119562.8, filed Oct. 16, 2008, both of which are hereby incorporated by reference. 
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     TECHNICAL FIELD 
     The present invention relates to power tools and, more particularly, to a reciprocating saw having a rotatable blade. 
     BACKGROUND OF THE INVENTION 
     A reciprocating saw generally includes a housing, a blade, a rear handle fixedly mounted to a rear end of the housing, and a motor mounted in the housing to drive the blade to do reciprocating movements. The blade is located at one end of the housing opposite the rear handle, and a forward handle is formed at the front end of the housing near the blade. Traditional reciprocating saws tend to lack adjustability, thus making them less useful in limited spaces. 
     In operation, the operator holds the forward handle and the rear handle respectively with both hands. To satisfy the requirement of different cutting directions, the orientation of the saw blade in relation to the rear handle is preferably adjustable so as to make the operation more comfortable. 
     U.S. Pat. No. 7,096,589 discloses a reciprocating saw having a blade which is rotated by swiveling a forward handle. Usually during the blade rotation the operator must hold down a locking element, and swivel the forward handle simultaneously. When the blade is rotated to a certain angle, the locking element is released and the forward handle is locked so that the rotation angle of the blade is achieved. Since the operator must always hold down the locking element while swiveling the forward handle, the operation is inconvenient and uncomfortable with such a structure. The present invention provides a reciprocating saw that the operator can quickly and easily rotate a blade relative to a rear handle. 
     SUMMARY OF THE INVENTION 
     The present invention provides a reciprocating saw which comprises a housing, a reciprocating shaft unrotatably connected relative to a blade, and rear handle, a forward handle rotatably mounted to the housing near the blade, the forward handle being capable of sliding relative to the reciprocating shaft, but incapable of rotating relative to the reciprocating shaft. The forward handle comprises at least one hole located thereon. The reciprocating saw further comprises a button connected to a locking element, and the locking element is capable of engaging or disengaging with the at least one hole of the forward handle. 
     The locking element can be disengaged from the at least one hole of the forward handle by moving the locking element through operation of the button, so that the forward handle can then be swiveled relative to the housing. Because the forward handle can not rotate relative to the reciprocating shaft and the blade is fixedly connected to the reciprocating shaft, swiveling the forward handle results in the blade being rotated relative to the housing. When the blade is rotated to a desired angle, the locking element can engage with the at least one hole of the forward handle with the aid of operating the button so that the forward handle can be locked to the housing. This operation is very easy and comfortable. 
     In another aspect of the present invention, a reciprocating saw comprises a housing, a reciprocating shaft unrotatably connected to a blade, a rear handle, and a forward handle rotatably mounted to the housing near the blade and being capable of sliding relative to the reciprocating shaft, but incapable of rotating relative to the reciprocating shaft. At least one hole is positioned within the forward handle. The reciprocating saw further comprises a locking element for engaging or disengaging with the at least one hole. A button having a rotatable shaft with a cam surface, wherein the cam surface cooperates with the reciprocating shaft to drive the reciprocating shaft to swing around a shaft mounted in the housing. The button further cooperates with the locking element to change the orientation of the blade. 
     With such a structure, when the locking element engages with the at least one hole, the relative position between the cam surface and the reciprocating shaft results in the cutting direction of the blade consisting with the swing direction of the reciprocating saw. Alternatively, when the locking element disengages from the at least one hole, the relative position between the cam surface and the reciprocating shaft results in movement of the blade of the reciprocating saw in the reciprocating direction only, not in a swing direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a reciprocating saw of a preferred embodiment according to the present invention. 
         FIG. 2  is partial cutaway view of the reciprocating saw shown in  FIG. 1  with a rear handle being removed. 
         FIG. 3  is an exploded view of a portion of the reciprocating saw shown in  FIG. 1 . 
         FIG. 4  is a perspective view of the reciprocating saw shown in  FIG. 1  with the blade being in an orbital position and the housing being removed. 
         FIG. 5  is a perspective view of the reciprocating saw shown in  FIG. 1  with the blade being in a non-orbital position and the housing being removed, 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-3 , a reciprocating saw of a preferred embodiment according to the present invention comprises a housing  1 , a rear handle  2  fixedly mounted to the housing  1 , a gear case cover  36  mounted in the housing, and a motor  4  mounted in the housing  1 . The motor  4  has an output shaft  5 , and a taper teeth portion formed on the output shaft  5 . The taper teeth portion engages with a gear  6  which is mounted on the shaft  7 . The gear  6  is driven to rotate through the rotation of the motor  4 . A protuberance  8  is formed on the gear  6  and deviated from a shaft axis of the gear  6 . The protuberance  8  protrudes into a yoke-shaped transmission element  9  fastened to a reciprocating shaft  10  while the reciprocating shaft  10  is slidably mounted in a slot  12  of a bracket  11 , so that the rotation of the gear  6  drives the protuberance  8  to rotate about the shaft  7 , which consequently drives the transmission element  9  and the reciprocating shaft  10  to do reciprocating motions. 
     The bracket  11  can be driven to rotate about a shaft  13  which is fixedly mounted to the housing so as to drive the reciprocating shaft  10  to swing around the shaft  13 . The swing of the reciprocating shaft  10  is transferred to a blade  51  simultaneously so as to make the blade  51  swing back and forth. For a cutting period in cutting operation to the workpiece, the blade  51  is driven to swing forward to help improve the cutting efficiency, and then the blade  51  is driven to swing backward in order to reduce wear of the blade teeth. The swing direction of the reciprocating shaft  10 , namely the swing direction of the blade  51 , should be consistent with the cutting direction of the blade  51 . In other words, the blade  51  should swing in its cutting plane, otherwise the reciprocating saw will not work normally. 
     A button  26  is mounted in the housing in a common manner and is kept at a suitable position. The button  26  includes a rotatable shaft  14 . A cam surface  15 , which is formed on the circumferential surface of a middle part of the rotatable shaft  14 , is in contact with a pin  16  which is fixedly mounted to the bracket  11 . A roller bearing  35  is mounted on the pin  16 . Through rotating the button  26 , the pin  16  can bring the roller bearing  35  away from a top surface of the gear  6  when a highest point of the cam surface  15  contacts the pin  16 , and alternatively the roller bearing  35  can come into contact with the top surface of the gear  6  when a lowest point of the cam surface  15  contacts the pin  16 . The surface of the gear  6  adjacent to the roller bearing  35  is a sloping surface  61  which inclines relative to the shaft  7  by a certain angle, thus, the sloping surface  61  move in a cycle rotating motion around the rotating shaft of the gear  6  to push the roller bearing  35  to move back and forth when the gear  6  rotates so that the bracket  11  will rotate around the shaft  13 . In this state, the reciprocating shaft  10  is located at a position close to the sloping surface  61  of the gear  6  and does cycle swing motions resulting from pushing force of the sloping surface  61  together with reciprocating motions. 
     Referring to  FIG. 2 , a forward handle  3  has a neck portion  17 , a flange surface  18 , and an internal hole  20 . A pair of guide slots  21  is formed in the internal hole  20 . A guide pin  22  is fixedly mounted to the reciprocating shaft  10 . The forward handle  3  is slidably mounted to the reciprocating shaft  10  by the cooperation of the guide slots  21  in the forward handle and the guide pin  22  in the reciprocating shaft. The flange surface  18  of the forward handle contacts a flange surface  19  of the housing  1 . A flange  23  is mounted to the rear end of the neck portion  17  of the forward handle  3 , which contacts another flange surface  24  of the housing, and is fixed in the housing through an elastic ring  25 , limiting the axial movement of the forward handle. With such a structure, the forward handle  3  can not rotate relative to the reciprocating shaft  10  when the reciprocating shaft  10  slides relative to the forward handle  3 . 
     As shown in  FIG. 3  and  FIG. 4 , a series of holes  23   a ,  23   b  are distributed uniformly on the circumferential surface of the flange  23 . The pair of holes  23   a  which are centrosymmetric with each other are through-holes, while and the other holes  23   b  are counterbored holes. In other embodiments, the through-holes  23   a  may have a deeper depth along the longitudinal direction of the reciprocation shaft, and the counterbored holes  23   b  may have a shallower depth along the longitudinal direction of the reciprocation shaft. As shown in  FIG. 4 , the cutting direction of the blade  51  will be consistent with the swing direction of the reciprocating shaft  10  when a locking element  32  is inserted into one of the through-holes  23   a . As shown in  FIG. 5 , the reciprocating shaft  10  cannot swing, but can only move in reciprocating motions when the locking element  32  is inserted into one of the counterbored holes  23   b.    
     The button  26  is connected to the locking element as follows. The rotatable shaft  14  of the button includes a flat portion  27  formed on an end of the rotatable shaft opposite the button. One end of a rod  28  is pivotally connected to a sleeve  29  through a shaft  33 , and a flat surface  30  is formed on the inner surface of the sleeve  29 . The sleeve  29  is mounted to one end of the rotatable shaft  14  through the engagement between the flat surface  30  of the sleeve  29  and the flat portion  27  formed on the rotatable shaft  14 . The other end of the rod  28  is pivotally connected the locking element  32  through a pivot shaft  31 . A guide slot  34  is formed on the gear cover  36 , and the locking element  32  is installed in the guide slot  34 . In another embodiment, the button may comprise a pinion, the locking element may comprise a rack, and the rotation of the button is transformed into longitudinal movements of the locking element through the engagement between the pinion and rack. In other embodiments, the button may be connected to the locking element through a cam. 
     When the button  26  is rotated, the reciprocating shaft  10  will lie in a swing position when the lowest point of the cam surface  15  contacts the pin  16 , with the cutting direction of the blade  51  consistent with the swing direction of the reciprocating shaft  10 , which results in that the locking element  32 , driven by the rod  28 , can be slided in the guide slot  34  and inserted into one of the through-holes  23   a  of the flange  23 . When the operator desires to change orientation of the blade  51 , the button  26  is rotated to disengage the locking element  32  from one of the through-holes  23   a  of the flange  23 , and the forward handle  3  is swiveled to position the locking element  32  to face one of the counterbored holes  23   b . The blade  51  rotates along with the reciprocating shaft  10  by a certain angle, and then the button  26  is rotated reversely to make the highest point of cam surface  15  contact the pin  16 , with a result that the roller bearing  35  is moved away from the sloping surface  61  of the gear  6 . The bracket  11  fixedly mounted with the pin  16  in the roller bearing  35  is pushed to force the reciprocating shaft  10  away relative to the sloping surface  61 , so that the reciprocating shaft  10  can not swing. At the same time, the locking element  32  engages one of the counterbored holes  23   b  of the flange  23 , as shown in  FIG. 5 , thereby limited rotation of the button  26  by an inner bottom surface of the one of the counterbored hole  23   b , so that the reciprocating shaft  10  can not reach the swing position. 
     In addition, the forward handle can be rotated to any position to perform the cutting operation according to the present invention. When the operator wants to change the orientation of the blade  51 , the button  26  is rotated to disengage the locking element  32  from one of the through-holes  23   a  or one of the counterbored holes  23   b  of the flange  23 , releasing the forward handle  3  so that the forward handle can swivel to a certain angle. The blade  51  thus is rotated by a certain angle along with the reciprocating shaft  10 , and the locking element  32  is not positioned to any hole of the flange  23 . The rotation of the button  26  will be limited by the surface of flange  23 , which faces the locking element  32 , so that the reciprocating shaft  10  can not reach the swing position. In this case, the forward handle is not locked, and any force produced in the cutting operation because of various factors, such as vibration, will effect the forward handle. However, the force is so minimal that it can be overcome easily by the operator with the forward handle being held steadily and being rotated controllably to any position so as to perform the cutting. In an alternative embodiment, the counterbored holes  23   b  may be eliminated, and only the through-holes  23   a  are retained. 
     The above described preferred embodiments are intended to illuminate the principle of the present invention, but not to limit its scope. It can be easily understood for those skilled in the art that many other modifications and variations of these preferred embodiments will be apparent and may be made without departing from the spirit and the scope of the invention as defined in the following claims.