Abstract:
A hand power tool that can be folded in its longitudinal span, having a housing base body that holds the driven tool insert and whose axis is adjustable—relative to the axis of a housing part serving as a handle—around a folding axis, is made especially compact and lightweight in that the hand power tool is embodied in the form of a universal saw that has the ability to be locked in various angular positions of the housing parts relative to one other; the housing part contains the drive motor, whose driven rotary motion is transmitted via an angle transmission to the tool insert—a saw blade—that is guided in the housing base body.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of priority of U.S. patent application Ser. No. 10/555,480 filed on Nov. 3, 2005 under 35 USC 119(e). The subject matter of the aforesaid U.S. patent application is further explicitly incorporated herein by reference thereto. 
         [0002]    The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2004 024 279.1 filed on May 15, 2004. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    The invention is based on a cordless screwdriver There is a known cordless screwdriver, the 3.6 V PSR made by Bosch, which has a convenient rod-like shape. The essentially cylindrical housing can fold at approximately the halfway point of its longitudinal span. The driven tool insert, in this case a screwdriver bit, is held in the front end of a front housing base body. The rear housing part, which serves as a handle, can be folded around a folding axis, which is perpendicular to the longitudinally extending main axis of the cordless screwdriver. This yields a hand power tool that can still be used easily even in very tight spaces. This cordless screwdriver has met all the demands and requirements made of it in terms of the kinds of uses described—but in fact only for handling screwdriving uses. 
       SUMMARY OF THE INVENTION 
       [0004]    Taking the above-described advantages of the prior art as a point of departure, a universal saw is created that has comparable advantages in terms of where it is used. Beyond this, a universally usable saw is created that is optimally able to handle both sawing as a jigsaw and sawing as a sabre saw. The universal saw embodied according to the invention can be used for both rough work and fine work. 
         [0005]    The universal saw can be made especially compact if the angle transmission and a motion converter that converts the driven rotary motion of the drive motor into the axially reciprocating working motion of the saw blade are combined into a transmission unit. To make it possible to use commercially available saw blades, which are adapted to various sawing uses, for sawing as a jigsaw or a sabre saw, it is expedient for the tool insert tappet to have a clamping system that is universally suitable for accommodating various insertion ends of commercially available saw blades, i.e. jigsaw blades with a so-called single-cam shank or sabre saw blades with a so-called universal shank. 
         [0006]    In order to achieve an optimum sawing function, it is expedient if the base plate, which is for resting on the work piece to be machined, can be moved from its normal position into various angular positions in which it can be optionally locked. 
         [0007]    Other advantageous embodiments ensue from the drawings, the associated description, and the defining characteristics contained in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a universal saw embodied according to the present invention, situated in a 90° angular position of its housing parts, in the form of a straight jigsaw, 
           [0009]      FIG. 2  shows the same universal saw in an extended 180° position in the form of a sabre saw, 
           [0010]      FIGS. 3 &amp; 4  each show enlarged details of the drive train and the locking of the housing parts of the universal saw according to  FIGS. 1 and 2 , essentially only in their linkage region, 
           [0011]      FIG. 5  shows a partial sectional depiction of a second exemplary embodiment of a universal saw in an extended 180° position in which it is not locked, 
           [0012]      FIG. 6  shows a detail of only the locking of the universal saw according to  FIG. 5 , in a view that is rotated by 90° in relation to  FIG. 5 , and 
           [0013]      FIG. 7  shows a locking element of the exemplary embodiment according to  FIG. 5 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    A universal saw  10  shown in  FIG. 1  and  FIG. 2  has a housing comprised essentially of two housing parts—a housing part  11  and a housing base body  12 . The housing part  11  can be adjusted in its angular position around a folding axis  13  in relation to the housing base body  12 .  FIG. 1  shows the universal saw  10  in a position in which it functions as a straight jigsaw in which the housing part  11  and the housing base body  12  in which a tool insert is guided—in this case a conventional saw blade  14  for jigsaws—are situated at a 90° angle to each other.  FIG. 2  shows the same universal saw in an extended 180° position in which it can be used as a sabre saw. In this intended use, a conventional sabre saw blade  15  is used in the housing base body  12 . 
         [0015]    A clamping system for the saw blades situated inside the housing base body  12  in a manner not shown in the drawing makes it possible to use saw blades  14  or  15  that are adapted to the respective sawing operation—either as a jigsaw for particularly fine work or as a sabre saw for rougher work, the clamping system having the capacity to clamp the special insertion ends of both jigsaw blades  14  and sabre saw blades  15 . On the underside of the housing base body  12 , which is oriented toward the work piece to be machined and from which the saw blade  14 ,  15  protrudes, a base plate  21  is situated in an intrinsically known fashion, which extends in an essentially normal orientation in relation to the working movement direction of the saw blade  14 ,  15  and serves to support the tool on the work piece—not shown here. The base plate  21  has an opening  22  through which the saw blade  14 ,  15  extends. In order to bring the base plate into the optimum position in relation to the work piece, for example when using the tool as a sabre saw, it can be moved out of its normal position into various angular positions in which it can be optionally locked. An operating lever  16  for operating the clamping system is situated at the free end of the housing base body  12 . As is clearly evident from  FIGS. 1 and 2 , the housing part  11  serves as a handle of the universal saw, which the user operating the hand power tool uses to hold and guide the universal saw. At the same time, the housing part  11  accommodates an electric drive motor for the universal saw, whose power supply cable  17  is situated at the free end of the essentially cylindrical housing part  11 . 
         [0016]    As mentioned above, the housing parts  11 ,  12  can be adjusted in terms of their angular position in relation to each other around the folding axis  13 , but must be locked in relation to each other in order to assure reliable function. This is executed by means of a locking device—not described until further below—that can be operated by means of an operating knob, which is mounted on the outside of the housing part  11  and in this instance is embodied as a slider  18  that can be moved along a surface line of the cylindrical housing part  11 . The slider  18  can be moved out of the locked position counter to the force of a spring, not shown in detail here, thus making it possible to adjust the angular position of the housing parts  11  in relation to each other. 
         [0017]    A power switch for the power supply to the drive motor is provided on the side of the housing part  11  not visible in  FIGS. 1 and 2 . 
         [0018]      FIGS. 3 and 4  show enlarged depictions of the drive train of the universal saw and the locking of the housing parts  11 ,  12 . For the sake of clarity, the outer contours of the universal saw  10  shown in  FIGS. 1 and 2  are depicted with only dashed lines. 
         [0019]      FIG. 3  shows the right end part of the electric drive motor  19 , which can, for example, be a universal motor. The motor shaft protrudes centrally from the drive motor and supports a fan impeller  20 . The free end of the motor shaft supports a driven pinion  23 , which meshes with a gear  24 . The driven pinion  23  and the gear  24  constitute an angle transmission in the drive train of the universal saw; the axis of the gear  24  is the driven axis of the angle transmission, which coincides with the folding axis  13  of the housing parts  11 ,  12 . This achieves a very compact design that is small, which is very useful in hand power tools. 
         [0020]    The side of the gear  24  equipped with the teeth also has the input member of a motion converter that converts the driven motion of the angle transmission  23 ,  24  and thus of the drive motor  19  into the reciprocating working motion of the saw blade  13 ,  14 . Consequently, the axis of the driven pinion  23  of the drive motor  19  and the axis of the common shaft  28  (folding axis  13 ) define a plane, yielding a very compact transmission unit. 
         [0021]    In this exemplary embodiment, the motion converter is comprised of an intrinsically known connecting rod drive whose input member—the crankshaft, so to speak—is embodied in the form of an eccentric pin on the gear  24 . The pin supports a connecting rod  26  whose other free end is connected in articulating fashion to a tool insert tappet  25 , which finally supports the saw blade  13 ,  14 —it constitutes the crosshead, so to speak, of the connecting rod drive. The tool insert tappet  25  has a rectangular cross section and is guided in the conventional fashion in sliding guides  27  in the housing base body  12 , as depicted in  FIG. 3 . 
         [0022]    For the sake of clarity, a full depiction of the connecting rod drive has been omitted in  FIG. 3  of the drawings because it involves machine elements that are known, particularly in jigsaws and sabre saws. These elements can also be subsequently seen in a different context in  FIG. 5 . 
         [0023]    On the left and right sides, the common shaft  28  is supported by ball bearings; only one of these ball bearings  29  is visible in  FIGS. 3 ,  4 , and  5 . The ball bearings  29  are respectively secured in associated bearing points in the housing base body, as depicted in  FIG. 5 . 
         [0024]    The housing part  11 , which is only depicted with dashed lines in  FIGS. 3 and 4 , is embodied in the form of a hollow cylinder in the region that contains the drive motor  19  and ends with two diagonally opposing bracket-shaped holding arms  30 ,  31 , the insides of which are provided with slide bearing points  32  in which the corresponding slide bearings on the outsides of the housing base body  12  engage, as shown in  FIG. 5 , thus constituting the folding support with the folding axis  13 . 
         [0025]    At the free end of the common shaft  28  toward the front in  FIGS. 3 and 4 , a rotatable, essentially circular disk  34  is provided as a locking element for locking the housing parts  11 ,  12  and has a flattened region on one side with which a connection in the housing base body  12  is produced in a manner that is fixed against relative rotation. Along its circumference, the disk  34  has a number of groove-like detent openings  35  that are open toward the edge. Each of these detent openings  35  is associated with a respective preset angular position between the housing part  11  and the housing base body  12  when a detent projection  36  of the respective other locking element engages in the detent opening  35 . 
         [0026]    This other locking element is the slider  18 , which can be moved along a surface line of the cylindrical housing part  11  counter to the force of a clamping spring, not visible in the drawing, which spring holds the slider  18  in its detent locking position. In  FIG. 3 , this detent locking position is the 90° position and in  FIG. 4 , it is the 180° position. The drawings do not show intermediate positions that are determined by the type of sawing to be performed with the universal saw—a finer or rougher cut within potentially limited working space. 
         [0027]    The function of this first exemplary embodiment of a universal saw is clearly evident. It should merely be noted that the locking of the housing parts  11 ,  12  is executed by actuating the slider  18 , which causes the locking elements to disengage from one another. Once the universal saw has been brought into the desired angular position, the user operating the hand power tool releases the slider  18 , causing the detent projection  35  to engage with the detent opening. 
         [0028]      FIG. 5  of the drawings, as mentioned previously, depicts an additional exemplary embodiment of a universal saw embodied according to present invention, this time situated in its extended 180° position. 
         [0029]    The angle transmission constituted by the driven pinion  23  of the drive motor  18  and the gear  24 , the motion converter embodied in the form of a connecting rod drive equipped with the connecting rod  26 , which are situated on the common shaft  28 , and the support of the common shaft  28  in ball bearings  29  that are secured in the housing base body correspond entirely to the first exemplary embodiment according to  FIGS. 3 and 4 , which is why the same reference numerals have been used. 
         [0030]    In the second exemplary embodiment of a universal saw shown in  FIG. 5 , a modified locking mechanism has been selected. The one locking element, which produces a form-locking engagement between the housing parts  11 ,  12 , is embodied as an octagonal sheet metal part  37 . It is inserted into a recess—which is situated coaxial to the common shaft  28 , adapted to the octagonal outer contour, and contained in the housing part  11  containing the drive motor  19 —and is thus attached to the housing part  11  in a manner that is secured against relative rotation. The sheet metal part  37  contains detent openings  38  embodied in the form of bores ( FIG. 7 ), which are situated on a graduated circle. Each pair of diagonally opposed bores  38  is associated with an angular position of the housing parts  11 ,  12  in relation to each other. The sheet metal part  37  is provided with a through bore  39  coaxial to the above-mentioned graduated circle on which the bores  38  are situated. 
         [0031]    In the detent position, detent projections  40  of the other locking element engage in the detent openings (bores)  38 . The detent projections  40  are cylindrical in shape and protrude at right angles from the two end regions of the other locking element embodied in the form of an essentially rectangular sheet metal body  41 . In the middle between the detent projections, the sheet metal body  41  has a shaft  42  fastened to it, likewise protruding at right angles. The shaft  42  is supported in the central through bore  39  of the other locking element embodied in the form of the sheet part  37 . At the end of the shaft  42  oriented away from the sheet metal body  41  and protruding from the through bore  39  is a coaxial, helical clamping spring  43 , which is braced against the sheet metal part  37  at one end and is braced against the inner edge of a push button  44  at the other end. It is clear in  FIGS. 5 and 6  that the clamping spring  43  encourages the detent elements to remain engaged (see  FIG. 6 ). 
         [0032]    If the user operating the hand power tool presses the push button  44 , then this disengages the detent elements counter to the force of the clamping spring  43 ; in this state shown in  FIG. 5 , the housing parts  11 ,  12  are able to move in relation to each other into a different angular position. 
         [0033]    In addition to the motion converter that is embodied as a connecting rod drive in both of the exemplary embodiments of the universal saw, there are naturally also other conceivable forms, which, if only the teaching relating to the orientation according to the present invention of the axes of the individual elements is retained, yield a modular transmission design that is very compact because it is comprised of a small number of parts and is correspondingly lightweight. Thus the input member of the motion converter can also be embodied in the form of a curved disk, for example a cam, with which the inner end of the tool insert tappet works in opposition. In this case, the tool insert tappet can be provided with a sliding guide or can be held against the curved disk by means of a spring.