Abstract:
The invention is based on a hand power tool, having a drive shaft ( 12, 14 ) supported in the housing ( 10 ) and having a mechanical percussion mechanism ( 16, 18, 20, 22, 24 ), which has a striker ( 26, 28 ) that is driven in hammering fashion via a driver unit ( 32, 34 ) supported on an intermediate shaft ( 30 ), which driver unit has at least one curve element ( 36, 38 ) by way of which at least one transmission unit ( 40, 42, 44, 46 ) with a tracer member is movable. 
     It is proposed that the curve element ( 36, 38 ) has at least one first and at least one second curved path segment ( 56, 58, 60, 62 ), the first curved path segment acting in a first axial direction of the intermediate shaft ( 30 ) and the second curved path segment acting in a second axial direction of the intermediate shaft ( 30 ).

Description:
BACKGROUND OF THE INVENTION 
   The invention is based on a hand power tool. 
   From German Patent Disclosure DE 41 21 279 A1, a drilling jackhammer with a drive shaft supported in a housing and with a mechanical percussion mechanism is known. The percussion mechanism has a striker, supported in the drive shaft embodied as a hollow shaft, and the striker is driven in hammering fashion via a driver unit supported on an intermediate shaft. The driver unit has a curve element, disposed on the intermediate shaft, that is embodied as an eccentric element and has an eccentricity in the radial direction. Via the eccentric element, a transmission unit that has a tracer member and is connected to the striker is movable. The tracer member is formed by a needle bearing, whose outer ring is formed by an articulation sleeve that surrounds the eccentric element. The articulation sleeve has a downward-oriented extension in which there is an opening. 
   A transmission member formed by a spring reaches with its first leg through the opening in the articulation sleeve. The transmission member is tiltably supported about a shaft structurally connected to the housing, and with its second, hooplike leg it surrounds the striker. 
   When the intermediate shaft is rotating, the tracer member and the first leg of the transmission member are moved in the radial direction by the motion of the eccentric element. Via the shaft structurally connected to the housing, the radial motion of the first leg is converted into an axial motion of the second leg, and the striker is driven in the axial direction. 
   SUMMARY OF THE INVENTION 
   The invention is based on a hand power tool, having a drive shaft supported in the housing and having a mechanical percussion mechanism, which has a striker that is driven in hammering fashion via a driver unit supported on an intermediate shaft, which driver unit has at least one curve element by way of which at least one transmission unit with a tracer member is movable. It is provided that the curve element has at least one first and at least one second curved path segment, the first curved path segment acting in a first axial direction of the intermediate shaft and the second curved path segment acting in a second axial direction of the intermediate shaft. Advantageously, the transmission unit can be moved in the axial direction directly via the tracer member, making it possible to avoid some components, and in particular a deflection mechanism for converting a radial motion into an axial motion. A percussion mechanism that is especially simple to preassemble can also be attained, along with an especially compact hand power tool. 
   Because of the disposition of the driver unit on the intermediate shaft, an existing gear stage can be used to adjust a number of impacts of the striker per revolution of the spindle, and an advantageous and in particular time-tested notch pattern can always be attained. 
   If the striker is supported via the drive shaft, then a space-saving design can be achieved in which additional components, in particular a shaft, oriented coaxially with the drive shaft, for supporting the striker, can be avoided. Time-tested standard components can largely be kept, and complicated new constructions can be avoided. It is also proposed that the striker is supported with a formed-on guide face on a guide face of the drive shaft, or directly on the drive shaft. Additional bearing components can be avoided, and a construction that is compact in the radial direction can be achieved. 
   The striker can be supported on or in the drive shaft. If the striker is guided in the drive shaft, then an embodiment according to the invention that can be employed in a drill hammer and/or jackhammer can be achieved. 
   If the tracer member is embodied as a spring element, additional spring elements can be dispensed with. However, especially advantageously, the tracer member is connected to the striker via a spring element, in particular making a space-saving construction in the radial direction possible. 
   The spring element can be formed of an elastic rubber element or some other spring element that appears appropriate to one skilled in the art. However, if the spring element is embodied by a helical compression spring that advantageously surrounds the striker, then a structurally simple, economical, space-saving percussion mechanism that is simple to assemble is achievable. 
   Especially advantageously, the tracer member is displaceably supported on the striker. The axial motion of the driver unit can be transmitted structurally simply to the striker, making economies in terms of both components and installation space possible. Fundamentally, however, it is also conceivable for the tracer member to be supported on a component that is separate from the striker, such as on the drive shaft, and so forth. 
   It is also proposed that the spring element is disposed radially inside the tracer member and is braced on a radially inward-pointing collar of the tracer member. An apparatus can be achieved in which the spring element is advantageously protected by the tracer member. If the inward-pointing collar of the tracer member engages the space between two windings of a single spring element, then the tracer member can move in both axial directions counter to the spring force of the single tracer member. This makes economies possible in terms of components, in particular a second spring element, as well as expenses. 
   In a further feature of the invention, it is proposed that the curve element be formed by a groove. A tracer member that has a disk can engage the groove, and a structurally simple transmission of motion that can be realized economically can be attained. However, the curve element can also be formed by an outer edge of a component, such as a swash plate and/or a wavy disk, and so forth. 
   The embodiment according to the invention can be used structurally simply in hand power tools that appear suitable to one skilled in the art, such as scrapers and so forth, but especially advantageously in percussion drills, drill hammers, and jackhammers. 
   Further advantages will become apparent from the ensuing description of the drawings. In the drawing, exemplary embodiments of the invention are shown. The drawing, description and claims include numerous characteristics in combination. One skilled in the art will expediently consider the characteristics individually as well and put them together to make useful further combinations. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1 , a schematic illustration of a percussion drill; 
       FIG. 2 , a percussion mechanism of the invention, with a curve element that is formed by a groove; 
       FIG. 3 , the percussion mechanism of the invention shown in  FIG. 2  for a drill hammer; 
       FIG. 4 , a variant of the percussion mechanism of  FIG. 2  in which a spring element is disposed radially inside a tracer member; 
       FIG. 5 , a variant of the percussion mechanism of  FIG. 2 , with a curve element embodied as a swash plate; and 
       FIG. 6 , a variant of the percussion mechanism of  FIG. 5 , in which the spring element is disposed radially inside the tracer member. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIGS. 1 and 2  schematically show a percussion drill, with an electric motor, not further shown, in a housing  10  along with a gear and a mechanical percussion mechanism  16 , which has a sleevelike striker  26  which is supported on a drive shaft  12  and is guided, via a formed-on guide face  66 , on a guide face  64  of the drive shaft  12 . 
   Downstream of a tool receptacle  78  counter to an actuating direction  76 , the percussion drill has a first grip  80 , secured to the housing  10  and extending perpendicular to the actuating direction  76 ; on a side of the housing  10  remote from the tool receptacle  78 , it also has a second grip  82 , formed onto the housing  10  and extending perpendicular to the actuating direction  76 . 
   The electric motor has an armature shaft  84 , onto which a pinion  86  is formed (FIG.  2 ). The pinion  86  meshes with a spur gear  88  that is disposed, in a manner fixed against relative rotation, on a side of an intermediate shaft  30  remote from the tool receptacle  78 . A driver unit  32  is supported on the intermediate shaft  30  and has a curve element  36 . The curve element  36  is formed by a groove and has a first curved path segment  56 , acting in a first axial direction of the intermediate shaft  30 , and a second curved path segment  60 , acting in a second axial direction of the intermediate shaft  30 . Via the curve element  36 , a tracer member  48  of a transmission unit  40  can be moved or driven. The tracer member  48  has a radially outward-pointing collar  90 , which positively engages the groove of the curve element  36 . 
   The sleevelike tracer member  48 , supported displaceably on the striker  26 , is operatively connected to the striker  26  via two spring elements  68 ,  70 , formed by helical compression springs, that radially surround the tracer member  48  and the striker  26 . The first spring element  68 , counter to the actuating direction  76 , is braced with its front end, pointing in the actuating direction  76 , on a radially outward-pointing collar  92  of the striker  26  and is braced with its rear end, pointing counter to the actuating direction  76 , on the collar  90  of the tracer member  48 . The second spring element  70 , counter to the actuating direction  76 , is braced with its front end, pointing in the actuating direction  76 , on the collar  90  of the tracer member  48  and by its rear end, pointing counter to the actuating direction  76 , a disk  94 , which is secured on the striker  26  counter to the actuating direction  76  via a securing ring  96 . 
   Upon a rotary motion of the armature shaft  84 , the pinion  86  of the armature shaft  84  meshes with the spur gear  88 , by way of which the intermediate shaft  30  is driven to rotate. On the side toward the tool receptacle  78 , the intermediate shaft  30  has a gear wheel  98 , disposed in a manner fixed against relative rotation, and a formed-on pinion  126 . The gear wheel  98  and the pinion  126  are each connected to a respective idler wheel  100 ,  110  supported on the drive shaft  12 , and these idler wheels can be coupled to the drive shaft  12  via a coupling body  102 . For switchover to a percussion mode, the drive shaft  12  can be released in its axial direction of motion via an eccentric element  104 , which is located on a side of the drive shaft  12  remote from the tool receptacle  78  (FIG.  2 ). 
   If the percussion drill is switched to percussion mode, and if it is pressed with its tool against a surface to be machined, the drive shaft  12  is moved in the axial direction counter to the actuating direction  76 , and a run-up disk  106  supported on the drive shaft  12  transmits the axial motion of the drive shaft  12 , via an axial bearing  108 , the idler wheel  110  and an axial bearing  112 , to the idler wheel  100 , which transmits its axial motion to a coupling sleeve  114 . Via a set of internal teeth  120 , the coupling sleeve  114  is connected to the gear wheel  98  and driven to rotate. 
   Because of the axial displacement on the intermediate shaft, the coupling sleeve  114 , with its side remote from the tool receptacle  78 , engages the driver unit  32  via cams, not shown in detail. The driver unit  32  is connected for driving to the intermediate shaft  30  via the coupling sleeve  114 , the internal teeth  120  of the coupling sleeve  114 , and the gear wheel  98 . 
   The driver unit  32  connected in terms of driving to the intermediate shaft  30  deflects the tracer member  48  in the actuating direction  76 , counter to the spring force of the spring element  68 , by means of the first curved path segment  56  acting in the actuating direction  76 . The spring element  68  is compressed in the actuating direction  76  by an inertia of the striker  26  and by the motion of the tracer member  48 . An ensuing expansion of the spring element  68  accelerates the striker  26  in the actuating direction  76  toward the tool receptacle  78  and strikes a shoulder  128  formed onto the drive shaft  12 . 
   The second curved path segment  60 , projected into the visible plane and following the first curved path segment  56  and acting counter to the actuating direction  76  deflects the tracer member  48  counter to the actuating direction  76  and counter to a spring force of the spring element  70 . The spring element  70  is compressed counter to the actuating direction  76  by an inertia of the striker  26  and by the motion of the tracer member  48 . An ensuing expansion of the spring element  70  accelerates the striker  26  counter to the actuating direction  76 . 
   If the user lifts the percussion drill from the surface to be machined, a spring element  116  presses the coupling sleeve  114  in the actuating direction  76 . The connection between the coupling sleeve  114  and the driver unit  32  is broken and the percussion mode is stopped. 
   In  FIGS. 3-6 , further alternative percussion mechanisms  18 ,  20 ,  22 ,  24  are shown in fragmentary form. Components that remain essentially the same are identified by the same reference numerals throughout. For characteristics and functions that remain the same, reference may be made to the description of the exemplary embodiment in  FIGS. 1 and 2 . The following description will be limited essentially to the differences from the exemplary embodiment of  FIGS. 1 and 2 . 
     FIG. 3  shows a percussion mechanism  18  for a drill hammer whose striker  28  is guided in a drive shaft  14  that is embodied as a hollow shaft. If the striker  28  is accelerated in the actuating direction  76 , it strikes a snaphead die  118 , which in turn acts on a tool not shown further. 
     FIG. 4 , compared to  FIG. 2 , shows an alternative percussion mechanism  20 , in which a single spring element  72  is disposed in a radially inner region of a tracer member  50  of a transmission unit  42 . The spring element  72  is braced by its front end, pointing in the actuating direction  76 , on a radially outward-pointing collar  92  of a striker  26  and by its rear end, pointing counter to the actuating direction  76 , on a disk  94 , which is secured to the striker  26  counter to the actuating direction  76  via a securing ring  96 . The tracer member  50  surrounds the striker  26 , is supported on the striker  26  via the collar  92  of the striker  26  and via the disk  94 , and is operatively connected to the striker  26  via a radially inward-pointing collar  74 , which engages the space between windings of the spring element  72 , and via the spring element  72  itself. Instead of a single spring element  72 , two spring elements which are braced on the collar  74  are also conceivable. 
     FIG. 5  shows an alternative percussion mechanism  22  to  FIG. 2 , with a driver unit  34  which is supported on an intermediate shaft  30  and has a curve element  38 . The curve element  38  is embodied as a swash plate. The curve element  38  positively engages the space between two radially outward-pointing collars  122 ,  124  of a tracer member  52  of a transmission unit  44  and moves the tracer member  52  via a first curved path segment  58 , acting in the actuating direction  76 , and via a second curved path segment  62 , acting counter to the actuating direction  76 . 
     FIG. 6  shows a percussion mechanism  24  as an alternative to that of  FIG. 5 ; in it, a single spring element  72  is disposed in a radially inner region of a tracer member  50  of a transmission unit  42 , as in the exemplary embodiment of FIG.  4 . The spring element  72  is braced by its front end, pointing in the actuating direction  76 , on a radially outward-pointing collar  92  of a striker  26  and by its rear end, pointing counter to the actuating direction  76 , on a disk  94 , which is secured on the striker  26  counter to the actuating direction  76  via a securing ring  96 . The tracer member  50  is operatively connected to the striker  26  via a radially inward-pointing collar  74 , which engages the space between windings of the spring element  72 , and via the spring element  72 . Instead of a single spring element  72 , two spring elements that are braced on the collar  74  are also conceivable. 
   LIST OF REFERENCE NUMERALS 
   
     
       
             
             
           
         
             
                 
             
           
           
             
               10 
               Housing 
             
             
               12 
               Drive shaft 
             
             
               14 
               Drive shaft 
             
             
               16 
               Percussion mechanism 
             
             
               18 
               Percussion mechanism 
             
             
               20 
               Percussion mechanism 
             
             
               22 
               Percussion mechanism 
             
             
               24 
               Percussion mechanism 
             
             
               26 
               Striker 
             
             
               28 
               Striker 
             
             
               30 
               Intermediate shaft 
             
             
               32 
               Driver unit 
             
             
               34 
               Driver unit 
             
             
               36 
               Curve element 
             
             
               38 
               Curve element 
             
             
               40 
               Transmission unit 
             
             
               42 
               Transmission unit 
             
             
               44 
               Transmission unit 
             
             
               46 
               Transmission unit 
             
             
               48 
               Tracer member 
             
             
               50 
               Tracer member 
             
             
               52 
               Tracer member 
             
             
               54 
               Tracer member 
             
             
               56 
               Curved path segment 
             
             
               58 
               Curved path segment 
             
             
               60 
               Curved path segment 
             
             
               62 
               Curved path segment 
             
             
               64 
               Guide face 
             
             
               66 
               Guide face 
             
             
               68 
               Spring element 
             
             
               70 
               Spring element 
             
             
               72 
               Spring element 
             
             
               74 
               Collar 
             
             
               76 
               Actuating direction 
             
             
               78 
               Tool receptacle 
             
             
               80 
               Grip 
             
             
               82 
               Grip 
             
             
               84 
               Armature shaft 
             
             
               86 
               Pinion 
             
             
               88 
               Spur gear 
             
             
               90 
               Collar 
             
             
               92 
               Collar 
             
             
               94 
               Disk 
             
             
               96 
               Securing ring 
             
             
               98 
               Gear wheel 
             
             
               100 
               Idler wheel 
             
             
               102 
               Coupling body 
             
             
               104 
               Eccentric element 
             
             
               106 
               Run-up disk 
             
             
               108 
               Axial bearing 
             
             
               110 
               Idler wheel 
             
             
               112 
               Axial bearing 
             
             
               114 
               Coupling sleeve 
             
             
               116 
               Spring element 
             
             
               118 
               Snaphead die 
             
             
               120 
               Internal toothing 
             
             
               122 
               Collar 
             
             
               124 
               Collar 
             
             
               126 
               Pinion 
             
             
               128 
               Shoulder