Abstract:
For a machine tool designed in particular as a saber saw, a configuration including a carrying frame is provided, via which the lifting rod and the support element are joined to form a unit that can be rotated about the longitudinal axis of the power tool, is mounted on the casing side, and guides a drive part of the lift drive on the lifting rod side.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP 2009/065309 filed on Nov. 17, 2009. 
     BACKGROUND OF THE INVENTION 
     1 Field of the Invention 
     The invention relates to a motor-driven power tool. 
     2 Description of the Prior Art 
     Motor-driven power tools of the above-mentioned type are known from DE 37 02 670 A1 and are complex in design. This results in a complicated structural embodiment and is accompanied by a certain susceptibility to malfunction, particularly under difficult working conditions. In addition, work options are partially limited because when the working tool is rotated around its longitudinal axis relative to the straight-ahead working direction, operating the power tool in orbital reciprocation mode is only possible at best to a limited degree. 
     OBJECT AND SUMMARY OF THE INVENTION 
     The object of the invention is to simplify the design of a motor-driven power tool of the type mentioned at the beginning, to provide it with a rugged embodiment, and in particular to also embody it so as to enable, as needed, an orbital reciprocation mode when the working plane of the working tool is rotated relative to the longitudinal axis out of its straight-ahead working direction, i.e. a “scrolling” working mode. 
     The starting point for the invention is the fact that the lifting rod and the supporting element are combined by means of a supporting frame to form a unit that is supported on the housing and is able to rotate around the longitudinal axis of the working tool, permitting the supporting element to maintain its position supporting the working tool in the working plane in all rotation positions of the working tool so that the support of the working tool by the supporting element is independent of the rotation position. It is thus possible to simplify the guidance for the lifting rod and to embody this guidance in the form of a sliding guide extending in the reciprocation direction, which is in turn supported on the supporting frame by means of a pivot axle extending transversely to the working plane. 
     If this support on the supporting frame is provided in the frame&#39;s end region oriented away from the working tool, it is then possible for the lifting rod, starting from the working tool or the holder for the working tool and extending through the support including the sliding guide, to be embodied as rigid and for the drive connection to the reciprocating drive to be integrated into the lifting rod close to the support, which results in a very compact design and also results in only small pivoting distances, particularly in the region of the drive connection to the reciprocating drive, when the working tool is being driven in orbital mode in the direction of the working plane, thus simplifying the embodiment of the drive connection. 
     Such a design permits the lifting rod to be used for executing the rotating drive for the supporting frame and therefore also for the working tool and the supporting element acting on it at the rear; the end of the lifting rod protruding beyond the supporting frame in the opposite direction from the working tool is connected to the corresponding rotating drive, which permits the use of conventional rotating drives without requiring further changes to the design. In the context of the invention, though, instead of introducing the rotary motion to the supporting frame indirectly via the lifting rod, it is also possible to use the rotary drive to act directly on the supporting frame, which is mounted on the housing in a way that permits it to rotate around the longitudinal axis of the working tool. 
     In the context of the invention, the reciprocating drive acting directly on the lifting rod is constituted by a crank mechanism embodied in the form of an eccentric drive and includes an eccentric pin, which is supported by a drive wheel mounted on the housing and engages in the guide slot of a slotted crank element; the slotted crank element extends transversely to the working plane of the working tool and the eccentric pin engages in the slot guide. 
     Preferably, the slotted crank element of the lifting rod is of one piece with the part of the lifting rod that is guided in the sliding guide in a rotationally fixed fashion in the direction of the longitudinal axis so that this part of the lifting rod can preferably be composed of flat stock, preferably embodied in the form of a stamped part. With a rigid attachment to the slotted crank element, the lifting rod, in its section extending from the slotted crank element to the tool holder, is suitably composed of round stock, in particular a rod-shaped round stock, making it possible to work with conventional tool holders. 
     Because the supporting frame is mounted so that it is able to rotate around the longitudinal axis of the working tool, depending on the specific rotation position, different angular positions are produced between the eccentric pin and the extension plane of the slotted crank element with its slot guide. The resulting friction conditions can be favorably controlled because the eccentric pin is supported by means of a needle bearing at least in the overlap region with the slot guide; the axial movement of the eccentric pin relative to the slotted crank element is relatively slight anyway due to the fact that the rotatability of the working tool is limited to a pivot angle on the order of +/−30°. 
     The supporting element is supported relative to the supporting frame by means of a pivot axle oriented transversely to the working plane on downward-protruding support legs provided on the cage-like supporting frame; the supporting element is preferably embodied in the form of an angle lever that is provided with an adjusting sector protruding toward its leg oriented away from the working tool, which adjusting sector lies within the permissible rotation range of the supporting frame in the overlap region with the adjusting element that is movable in the axial direction—preferably parallel to the longitudinal axis—and is acted on by the adjusting drive for the orbital motion of the working tool. 
     Other advantages and advantageous embodiments ensue from the claims, the description of the drawings, and the drawings themselves. 
    
    
     
       BRIEF DESCRITION OF THE DRAWINGS 
         FIG. 1  is a perspective, schematic overview of a power tool according to the invention, embodied in the form of a jigsaw, reduced to the parts essential to comprehension of the invention and in particular, largely without housing parts, and 
         FIGS. 2  shows a partially simplified depiction of the power tool from  FIG. 1  in a front view. 
         FIG. 3  shows a partially simplified depiction of the power tool from  FIG. 1  in a side view. 
         FIG. 4  shows a partially simplified depiction of the power tool from  FIG. 1  in a top view. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The power tool  1  shown in the figures is embodied in the form of a jigsaw  2  whose working tool  3  is constituted by a saw blade  4  that is driven to execute a reciprocating motion along a direction of axial movement  40  defined by an longitudinal axis  8  of the working tool  3 . The saw blade  4  is attached via a saw blade holder  5  to a lifting rod  6  that is acted on by a reciprocating drive  7 . 
     The saw blade  4  provided as the working tool  3  has a longitudinal axis  8  lying in the working plane of the saw blade  4 , which has a set of teeth  9  in front and whose opposing saw blade spine  10  is supported against a supporting element  11  by means of a supporting roller  12 . The supporting element  11  is embodied in the form of a pivot lever  13 , which is linked to a supporting frame  15  by means of a pivot axle  14 . With a cage-like embodiment, the supporting frame  15  has a support ring  16 , which is situated at the upper end in the drawing and oriented away from the working tool  3 , and has a lower support ring  17 ; these rings are connected to each other in stationary fashion by means of a longitudinal strut  18  depicted in the form of a longitudinal bar. From the support ring at the lower end in the drawing, support legs  19  protrude downward, with the pivot axle  14  passing through them. Protruding from the rear toward the arms of the angular supporting element  11  extending upward in the drawing, a plate-shaped adjusting sector  20  is provided, which is acted on by the adjusting element  21  of a stationarily mounted adjusting drive  22  provided for the orbital drive. The latter is not depicted in detail and is situated behind a support plate  23  mounted in stationary fashion relative to the housing of the power tool  1  and therefore on the opposite side from the working tool  3  provided at the front along with its devices provided for the reciprocating and/or rotary drive. The supporting frame  15  is supported via at least one of its support rings  16 ,  17  in rotary fashion relative to the housing  24 , which is depicted only schematically, by means of a bearing that is symbolically depicted by means of a bearing  25  that is supported relative to the upper support ring  16 . 
     The lifting rod  6  extends axially through the supporting frame  15  and its upper section adjacent to the upper support ring  16  preferably includes the lifting rod drive part of the reciprocating drive  7 , which as a slotted crank element  26 , is equipped with a slot guide  27  extending transversely to the working plane, in which an eccentric pin  28  engages, which is provided on a drive wheel  29  of the crank mechanism  30  embodied in the form of an eccentric drive and is part of the reciprocating drive  7 . 
     In the opposite direction from the working tool  3 , adjoining the slotted crank element  26 , the lifting rod  6  continues in a section  31  through which passes a sliding guide  32  that is a component of a strut  33 , which extends transversely to the working plane and is supported in rotatable fashion relative to the upper support ring  16  by means of a pivot axle  34  likewise extending transversely to the working plane. 
     The section  31  of the lifting rod  6  including the slotted crank element  26  is connected to the strut  33  by the sliding guide  32  in a fashion that is rotationally fixed, but permits it to move in the direction of the longitudinal axis  8 ; the strut  33  in turn is able to pivot around the pivot axle  34  so that for the lifting rod  6 , which constitutes a continuous, rigid unit over its entire length, a pivoting support is produced, around whose pivot axle  34  the lifting rod  6  with the saw blade  4  provided in its extension can be moved in orbital fashion by means of the supporting element  11  when acted on by the adjusting drive  22 . 
     The upper section  31  of the lifting rod  6  that includes the slotted crank element  26  is preferably composed of flat stock and can therefore also be inexpensively embodied in the form of a stamped part and toward the bottom, transitions into a rod part  35  with a round cross section that is connected to the slotted crank element  26  in stationary fashion and is provided with the saw blade holder  5 . 
     The above-explained design once again offers the possibility of providing the lower support ring  17  with a sliding guidance for the lifting rod  6  in the direction of its working plane so that a transverse guidance for the lifting rod  6  is also provided in the region of the lower support ring  17 . For example, this can be achieved by means of a base for the lower support ring  17  that is provided with a corresponding oblong hole-shaped recess that accommodates the rod part  35  of the lifting rod  6  in a guiding fashion. 
     In the above-explained embodiment, the supporting frame  15  constitutes the rotationally fixed sliding guidance for the lifting rod  6  and supporting element  11  and, through the integration of the slotted crank element  26  into the lifting rod  6 , also constitutes the rotationally fixed guidance for the slotted crank element  26  relative to the supporting frame  15  so that with a rotational movement of the supporting frame  15 , a synchronous movement of these parts occurs. The rotational movement, which is not shown, can take place directly through a rotary drive engaging the supporting frame  15  or also indirectly through a rotary drive engaging the lifting rod  6 , in particular its section  31 . 
     With regard to the angular position of the slotted crank element  26  relative to the eccentric pin  28  that changes when the supporting frame  15  is rotated around the longitudinal axis  8  and the resulting sliding movements, it turns out to be advantageous for the eccentric pin  28  to be supported in the slot guide  27  by means of a needle bearing or also optionally for it to be at least partially embodied in the form of a needle bearing. 
     The above-explained design of the jigsaw  2  results in a very compact, rugged embodiment in which the working tool in the form of the saw blade is supported in the respective working plane by the supporting element  11  in all rotation positions so that even in rotation positions that differ from the straight-ahead working direction, the saw blade  4  is supported by the supporting element II in the working plane as a result of which, the saw blade  2  can also be operated in so-called scrolling mode, i.e. can be operated as a scrolling jigsaw with an orbital action in addition to the reciprocating drive, with a saw blade  4  that is pivotable in the direction of the saw blade plane. The rotary drive for the lifting rod  6  is symbolically depicted by means of an arrow and is labeled with the reference numeral  36 , which also depicts a direction of rotary movement about the longitudinal axis  8  of the working tool  3 . 
     The foregoing relates to the preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.