Abstract:
A hand-held power tool is proposed, having a drive device for driving a tool, which is arranged in a housing of the power tool. A handle of the power tool, which is movably connected to the housing of the power tool, is vibration-damped by a movable compensating element. For this purpose, the movable compensating element is operatively connected to the handle and/or the housing of the power tool by a deflecting system.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP2008/058740 filed on Jul. 7, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Prior Art Field of the Invention 
     The invention relates to a handheld power tool. 
     The handheld power tool has a drive device, disposed in a power tool housing, for driving a tool. The drive device and/or the tool generate oscillations, which are transmitted as vibration to a power tool user. The handheld power tool furthermore has a handle that is vibration-damped via a movable compensating element. The movable compensating element is preferably disposed in the power tool housing and/or in the handle. Preferably, the movable compensating element is embodied as a movably supported counterweight. The mass inertia of the counterweight acts in damping fashion on the amplitude of the vibrations. 
     2. Description of the Prior Art 
     Methods and devices for vibration-damping of the handle are known. For instance, spring-loaded and/or elastically damping handles are employed. In arrangements, the handle is decoupled from the vibration-excited power tool housing via the spring/damper system. In addition, split, spring-loaded and/or damped housings are used, in order to decouple the housing from the vibration-excited components, such as the drive device. 
     ADVANTAGES AND SUMMARY OF THE INVENTION 
     The handheld power tool of the invention has a movable compensating element, which is operatively connected to the handle and/or the power tool housing via a deflection system. By means of the deflection system, an action of the movable compensating element on the handle is achieved. The operative relationship between the handle and the movable compensating element that is brought about by the deflection system has the advantage that the movable compensating element can be constructed quite compactly and provided with only a slight mass. Thus at comparatively little effort or expense, considerable damping of the vibration transmitted to the power tool user is attained. 
     It is considered to be a further advantage that the movable compensating element does not contribute significantly to the total weight of the handheld power tool; that is, the capability of manipulating of a handheld power tool vibration-damped in accordance with the invention is improved perceptibly. 
     By means of the drive device of the handheld power tool, vibrations along a main axis of vibration are generated, particularly in the case of a hammering drive of the tool, such as rotary and/or chisel hammers. By means of a degree of freedom of the movable compensating element, which extends essentially in a main axis of vibration of the power tool housing, an advantageous and especially compact structural form of the handheld power tool according to the invention can be attained. 
     In a preferred embodiment, the deflection system has at least one and preferably two lever arms rotatably connected to one another. A reactive force caused by the drive device and/or the tool acts on a first lever arm. As a result of this force introduction, a highly effective and at the same time economical realization of the handheld power tool of the invention can be achieved. 
     An especially economical and compact embodiment of the handheld power tool of the invention can be attained by the action of a second lever arm on the movable compensating element. 
     In a preferred embodiment of the handheld power tool of the invention, the deflection system is constructed of two lever arms. One lever arm is connected, preferably rigidly, to the handle. Through an engagement opening in the power tool housing, this first lever arm engages a rotatable engagement point on the second lever arm. The second lever arm is supported by a rotary bearing point that is connected to the power tool housing. The rotatable engagement point is disposed at a spacing A from this rotary bearing point. The spacing A advantageously acts as an additional tuning parameter for the damping system. 
     In an alternative embodiment, a first lever arm is connected, preferably rigidly, to the power tool housing. Through a leadthrough opening in the handle, the first lever arm engages a rotatable engagement point on the second lever arm. The second lever arm is rotatably supported at a rotary bearing point that is connected to the handle. The rotatable engagement point is located at a spacing A from the rotary bearing point. The spacing A, which is freely selectable in its dimensions, advantageously permits an additional tuning of the damping system. It is considered to be a further advantage that producing a handheld power tool of the invention requires no interventions inside the power tool housing. 
     An especially economical embodiment of a handheld power tool of the invention can be attained by means the solid connection between the second lever arm and the movable compensating element. Preferably, the second lever arm and the movable compensating element are embodied in one piece. 
     By means of a deflection system with a third lever arm, especially effective vibration damping of the handheld power tool of the invention can be achieved. To that end, the third lever arm is connected rotatably to the second lever arm at a spacing B from the rotatable engagement point. The third lever arm now acts on the movable compensating element. 
     A compact embodiment of a deflection system according to the invention with three lever arms can be achieved by providing that the third lever arm is solidly connected to the movable compensating element. In an embodiment that is furthermore especially economical, the third lever arm is embodied in one piece with the movable compensating element. 
     By the use of at least one thrust-pivot gear mechanism in the deflection system, an especially strong action of the movable compensating element is attained. 
     An especially compact embodiment that at the same time is adaptable to given installation spaces is achieved by using at least one cable pull device in the deflection system. 
     A deflection system with at least one pressure body system is especially flexibly usable with regard to installation space and at the same time has especially good tunability of the damping properties. 
     An advantageous further development of the handheld power tool of the invention can be attained by means of a disposition of at least one and preferably two restoring elements on the movable compensating element. Upon a deflection of the movable compensating element from a position of repose, the restoring element exerts a restoring force FR on the movable compensating element. As a result, degrees of freedom for the design of the damping system are advantageously attained. 
     A further advantageous refinement of the handheld power tool of the invention can be attained by means of the disposition of at least one and preferably two damping elements on the movable compensating element. Upon a deflection of the movable compensating element from a position of repose, the damping element acts in damping fashion on the motion of the movable compensating element. Advantageously, degrees of freedom are thus obtained in terms of the design of the damping system. In particular, the damping system of the handheld power tool of the invention can be adapted ideally to the load profile. 
     A handle for a handheld power tool, in particular a rotary anchor chisel hammer, is connected movably to a power tool housing of the handheld power tool. Moreover, the handheld power tool has at least one vibration-damping movable compensating element, preferably at least one movably supported counterweight. According to the invention, the movable compensating element is operatively connected to the handle and/or the power tool housing via a deflection system, as a result of which especially effective and at the same economical vibration damping of the handle is achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Several exemplary embodiments of the invention are shown in the drawings and explained in further detail in the ensuing description in conjunction with the drawings, in which: 
         FIG. 1  is a schematic side view of a handheld power tool of the invention with a two-arm deflection system; 
         FIG. 2  is a schematic side view of a handheld power tool of the invention with a three-arm deflection system; 
         FIG. 3  shows a handheld power tool of the invention as in  FIG. 2 , with at least one restoring element and/or damping element in addition; 
         FIG. 4  is a schematic side view of a handheld power tool of the invention with a two-arm deflection system, in which the movable compensating means is disposed in the handle; 
         FIG. 5  shows an alternative embodiment to  FIG. 4 ; 
         FIG. 6  shows an expanded embodiment compared to  FIG. 4 , having at least one restoring element and/or damping element; 
         FIG. 7  shows an expanded embodiment of  FIG. 5 , with a restoring element and/or damping element; 
         FIG. 8   a  shows an alternative embodiment to  FIG. 4 , using a thrust-pivot gear mechanism with a circular pivot element; 
         FIG. 8   b  shows an alternative embodiment to  FIG. 8   b  with a cycloidal pivot element; 
         FIGS. 9   a  and  9   b  show alternative embodiments to  FIG. 1 , using a thrust-pivot gear mechanism with a circular and cycloidal pivot element, respectively; 
         FIG. 10  shows a further embodiment analogous to  FIG. 4 , with a cable pull device as the deflection system; 
         FIG. 11  shows a further embodiment analogous to  FIG. 4 , with a pressure hull system as the deflection system. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The handheld power tool  10  shown in the examples is an electrically operated handheld power tool. It has at least one drive device  12 , comprising at least one electric motor  12   a  with at least one motor shaft  12   b  and at least one gear mechanism  12   c  coupled to the motor shaft  12   b . The gear mechanism  12   c  serves at least to convert a rotary motion of the motor shaft  12   b  into a translational motion along a power tool axis  12   d  defined by the tool. The handheld power tool  10  can be embodied as a chisel hammer and/or rotary hammer, in which the drive device  12  serves to actuate a hammer impact mechanism  13 . Further examples of handheld power tools  10  with at least one drive, alternating between two terminal positions, of a tool are percussion screwdrivers, percussion power drills, and compass saws, straight back hand saws, or saber saws. 
     The handheld power tool  10  of the invention shown in  FIG. 1  has a power tool housing  14  and a handle  16  connected to the power tool housing  14 . The drive device  12  is disposed in the power tool housing  14 . The drive device  12  here is indicated schematically as a hammer impact mechanism. The handle  16  is connected to the power tool housing  14  via a spring element  18 . In other embodiments, the handle  16  can additionally or alternatively be connected to the power tool housing  14  via at least two spring elements and/or at least one, two or more damping elements. 
     The handheld power tool  10  of the invention furthermore has a deflection system  20 . The deflection system  20  includes a first lever arm  22  and a second lever arm  24 . 
     The first lever arm  22  is rigidly connected to the handle  16 . The first lever arm  22  protrudes into the power tool housing  14  through an engagement opening  26 . In other embodiments, the first lever arm may also be connected to the handle  16  elastically, rotationally, and/or displaceably. 
     The second lever arm  24  of the deflection system  20  is disposed in the power tool housing  14 . The second lever arm  24  is rotatably supported at a rotary bearing point  28  that is braced on the power tool housing  14 . The movable compensating means  30  is embodied as a counterweight  31 . The counterweight  31  is disposed on the end  32  of the second lever atm  24  that is remote from the rotary bearing point  28 . The counterweight  31  is connected solidly to the second lever arm  24 . 
     The end reaching through the engagement opening  26  of the first lever arm  22  engages a rotatable engagement point  34  on the second lever arm  24 . The rotatable engagement point  34  is spaced apart from the rotary bearing point  28  by a first spacing A. 
     The function of the handheld power tool  10  of the invention will now be explained. As a result of the action of the drive device  12 , a reactive force  36 , called a repulsion force  35 , acts on the power tool housing  14 . The vibrations thus generated propagate preferentially along a main axis of vibration  38  in the power tool housing  14 . 
     The handle  16  is braced on the power tool housing  14  by the spring element  18 . The rotary bearing point  28  of the second lever arm  24  connected rigidly to the power tool housing  14  follows a motion of the power tool housing  14  directly. Because of its mass inertia, the movable compensating means  30  on the end  32  of the second lever arm  24  remote from the rotary bearing point  28  follows this motion only with a delay. Via the rotatable engagement point  34  disposed at a second spacing B from the movable compensating means  30 , the delayed motion is transmitted to the first lever arm  22 . Since the first lever arm  22  is rigidly connected to the handle  16 , a relative motion  40  is created between the handle  16  and the power tool housing  14 . As a result of this relative motion  40 , vibrations or oscillations are sent onward to the handle with a reduced amplitude. 
     By the dimensioning of the movable compensating means  30  or in other words of the counterweight  31 , tuning of the damping behavior relative to the handheld power tool  10  is possible. 
     During the design of the handheld power tool  10 , the action of the movable compensating means  30  can be varied by way of the distribution of the spacings A and B. Thus the spacings A and B act as design parameters. 
       FIG. 2  shows a refinement of the handheld power tool  10  of the invention, as a second embodiment. Identical elements have the same names and are identified by the same reference numerals. A third lever arm  42  is connected rotatably to the end  32  of the second lever arm  24  remote from the rotary bearing point  28  at a spacing B from the rotatable engagement point  34  (as labeled in  FIG. 1 ). The third lever arm  42  here is guided by two guide elements  44  parallel to the main axis of vibration  38 . By varying the number of guide elements  44 , in particular by having one, three or more guide elements  44 , variants of the handheld power tool  10  of the invention can be obtained. A further development of the handheld power tool  10  of the invention is obtained by using bearing elements, such as slide bearings, needle bearings, or roller bearings, to improve the friction properties of the guide elements  44 . 
     The third lever arm  42  acts on the movable compensating means  30 , embodied here as a counterweight  31 . In a preferred embodiment, the counterweight  31  is connected solidly to the third lever arm  42 . In particular, in a further development of the handheld power tool  10  of the invention, the counterweight  31  and the third lever arm  42  can be embodied in one piece. 
     The guidance of the third lever arm  42  in the guide elements  44  assures that the movable compensating means  30  is movable only in the direction of the main axis of vibration  38 . As a result, it has an especially efficient damping action on vibrations along the main axis of vibration  38 . 
     A preferred further development of the handheld power tool  10  of the invention is shown in  FIG. 3 . Identical elements are given the same names and provided with the same reference numerals whether enumerated in the present figure or previously. In the direction of the degree of freedom  46  of the movable compensating means  30 , there are at least two restoring elements  48  and/or damping elements  50 . The restoring elements  48  and/or damping elements  50  thus act in the direction of the degree of freedom  46  on the movable compensating means  30 . The restoring elements  48  are embodied in  FIG. 3  in an especially preferred form as spring elements  49 . 
     Upon a deflection of the movable compensating means  30  out of a position of repose, the restoring elements  48  generate a restoring force FR on the movable compensating means  30 . This force seeks to shift the movable compensating means  30  back into the position of repose. 
     Conversely, damping elements  50  act in damping fashion on the motions of the movable compensating means  30 . 
     Variants of this exemplary embodiment of a handheld power tool  10  of the invention are obtained in particular by varying the number of restoring elements  48  and/or damping elements  50 , particularly by having one, three, four or more restoring elements  48  and/or damping elements  50 . An especially preferred variant is obtained by combining at least one restoring element  48  and at least one damping element. Further embodiments are obtained by varying the connecting means for connecting the restoring elements  48  and/or damping elements  50  to the movable compensating means or the power tool housing. In particular, the restoring elements  48  and/or damping elements  50  can be connected solidly to the movable compensating means or to the power tool housing or may merely contact them. 
     In  FIG. 4 , a further exemplary embodiment of a handheld power tool  10  of the invention is shown, in which the movable compensating means  30  is disposed in the handle  16 . Identical elements are given the same names and provided with the same reference numerals. The handle  16  is braced on the power tool housing via a first spring element  18  and a second spring element  19 . 
     In a departure from the exemplary embodiments described above, the first lever anti  22  is connected rigidly to the power tool housing  14 . The handle  16  has a leadthrough opening  52 , through which the first lever arm  22  is introduced into the handle  16 . 
     The second lever arm  24  is pivotably supported in a rotary bearing point  28  connected rigidly to the handle  16 . The first lever arm  22  engages the second lever arm  24  at a rotatable engagement point  34 . The rotatable engagement point  34  is disposed at a spacing A from the rotary bearing point  28  on the second lever arm  24 . 
     Variants are obtained in particular by the selection of the connection of the first lever arm  22  to the power tool housing and/or of the second lever arm  24  to the handle. In particular, the connection may be embodied elastically, rotationally elastically, and/or displaceably. 
     The movable compensating means  30  is disposed on an end of the second lever arm  24  remote from the rotatable engagement point  34 . 
     Analogously to the exemplary embodiments described above, the drive device  12  generates a reactive force  36  that sets the power tool housing  14  in motion. The first lever arm  22 , connected essentially rigidly to the power tool housing  14 , transmits this motion to the pivotably suspended second lever arm  24 . The direction of motion at the movable compensating means  30  relative to the motion of the power tool housing  14  is reversed by disposing the rotatable engagement point  34  and the movable compensating means  30  diametrically opposite one another, as viewed from the rotary bearing point  28 . 
     In a departure from the preceding exemplary embodiment, in  FIG. 5  an embodiment is shown in which the second connection between the handle  16  and the power tool housing  14  is made via a pivot shaft  54 . Further advantageous embodiments are obtained by means of elastic support of the pivot shaft. 
     The exemplary embodiment shown in  FIG. 6  combines the exemplary embodiment of  FIG. 4  with two restoring elements  48  and/or damping elements  50 . The restoring elements  48  and/or damping elements  50  act analogously on the movable compensating means  30  to what has already been described for the exemplary embodiment of  FIG. 3 . Analogous refinements of the handheld power tool  10  of the invention as in the description for  FIG. 3  are also possible. 
     In  FIG. 7 , an embodiment in accordance with  FIG. 5  is shown, which is supplemented with two restoring elements  48  and/or damping elements  50 . The mode of operation of the restoring elements  48  and/or damping elements  50  is as described above. Moreover, the movable compensating means  30  (not enumerated here, analogous to embodiments described above) is supported displaceably on a rigid, rectilinear guide rail  56 . The second lever arm  24  engages a rotary bearing  58  on the movable compensating means  30 . If because of a reactive force  36  acting on the first lever arm  22  the second lever arm pivots about the rotary bearing  58 , then the movable compensating means is displaced along the guide rail  56 . Further refinements of the guidance of the movable compensating means  30  are possible by means of special guide rails  56 , which for example are shaped hyperbolically or parabolically and/or are not rigid. 
       FIGS. 8   a  and  8   b  show two versions of a further exemplary embodiment of a handheld power tool  10  of the invention. In a distinction from the exemplary embodiments described above, the first lever arm  22  and the second lever arm  24  are operatively connected to one another by means of at least one thrust-pivot gear mechanism  60 , in particular a rack and gear wheel mechanism, for instance, or a thrust rod/friction rod mechanism. The first lever arm  22  has a thrust element  62 , in particular a toothed segment or friction segment, for example. This thrust element  62  is disposed on the side of the first lever arm  22  oriented toward the movable compensating means  30 . The second lever arm  24  is preferably connected solidly to a pivot element  64 , here embodied in particular as a circular gear wheel or friction wheel ( 64   a ,  FIG. 8   a ) or cycloidal gear wheel or friction wheel ( 64   b ,  FIG. 8   b ). The pivot element  64  is rotatably supported about a pivot shaft  66  connected solidly, preferably rigidly, to the handle  16 . 
     Analogously to the exemplary embodiments described above, the drive device  12  generates a reactive force  36  that sets the power tool housing  14  in motion. The first lever arm  22  connected essentially rigidly to the power tool housing  14  transmits this motion to the second lever arm  24  via the thrust-pivot gear mechanism  60 . As a result of the disposition of both the thrust-pivot gear mechanism  60  and the movable compensating means  30  diametrically opposite the pivot shaft  66 , the direction of motion at the movable compensating means  30  relative to the motion of the power tool housing  14  is reversed. 
     The damping action of the movable compensating means  30  in this arrangement is determined among other factors by the spacing B of the movable compensating means  30  from the pivot shaft  66  and by the spacing A between the pivot shaft  66  and the action range  68  of the thrust-pivot gear mechanism  60 . The action of the movable compensating means  30  can also be varied by means of the design of a runround pivot element  64 . 
     Refinements of these exemplary embodiments can be obtained by expansion and combination with characteristics of the previous exemplary embodiments, in particular by combination with restoring elements  48  and/or damping elements  50  that act on the movable compensating means  30 , and/or by supplementing it with a third lever arm  42  as in  FIG. 2  and/or a guide rail  56  in accordance with  FIG. 7 . 
       FIGS. 9   a  and  9   b  show a further embodiment of a handheld power tool according to the invention having at least one thrust-pivot gear mechanism  60  between the first lever arm  22  and the second lever arm  24  (not enumerated here); the movable compensating means  30  is disposed in the power tool housing  14 . Here, the first lever arm  22  and the movable compensating means  30  are disposed on one and the same side of the pivot shaft  66 . To that end, the thrust element  62  points away from the movable compensating means  30 . The second lever arm  24  is connected solidly, preferably rigidly, to a pivot element  64  of the thrust-pivot gear mechanism  60 . The pivot element  64  has a circular shape ( 64   a ,  FIG. 9   a ), cycloidal shape ( 64   b ,  FIG. 9   b ), or other shape. 
     In their mode of operation, these exemplary embodiments correspond to the embodiments of  FIGS. 8   a  and  8   b.    
     Refinements of these exemplary embodiments are obtained by additions and combinations suing characteristics of the preceding exemplary embodiments, in particular by combination with restoring elements  48  and/or damping elements  50  that act on the movable compensating means  30  and/or by adding with a third lever arm  42  as in  FIG. 2  and/or a guide rail  56  in accordance with  FIG. 7 . 
     By means of further, alternative arrangements with at least two and preferably three or four lever arms, which deflect a reactive force, acting on the power tool housing  14 , to a movable compensating means  30  in such a way that the movable compensating means  30  acts in damping fashion on the motion of the handle  16 , further advantageous refinements of and additions to the handheld power tool  10  of the invention are possible. 
     In some cases, a disposition with a second and third lever arm  24 ,  42  connected to the movable compensating means  30  not rigidly but movably. Besides the embodiment shown in this exemplary embodiment, further variant ways of connecting the movable compensating means  30  to the second and third lever arms  24 ,  42  acting on the movable compensating means  30  are conceivable, such as with a toothed element or an alternative form-locking connection. 
     Alternatively or in addition, a suitable deflection system  20  according to the invention can be constructed on the basis of cable pull and/or Bowden cables and/or pneumatic and/or hydraulic elements. 
       FIG. 10  shows a handheld power tool  10  of the invention in which the deflection system  20  (not enumerated here) is constructed on a cable pull device  68 . The cable pull device  68  includes at least one and preferably two, three or more deflection rollers  70 . The deflection rollers  70  are each supported rotatably in the handle via a respective rotation shaft  72 , and the rotation shafts  72  are connected solidly, preferably rigidly, to the handle. The cable pull device  68  furthermore includes a traction element  74 , here embodied as a traction cable  74   a . The traction cable is connected, preferably solidly, by its first end  76  to the power tool housing  14 . In the present exemplary embodiment, the first end  76  is secured to a fastening eyelet  78  on the power tool housing  14  (not enumerated here). On the second end  80 , the movable compensating means  30  (not enumerated here) is connected, preferably solidly. 
     The cable pull device  68  furthermore has a restoring element  82 , here embodied as a restoring spring  82   a . The restoring element  82  is disposed between an inner end face  84  and the movable compensating means  30  in such a way that upon the occurrence of a tensile force FZ on the traction cable, a restoring force FR acts on the movable compensating means. In a preferred embodiment, the restoring element  82  is ideally prestressed in such a way that upon a motion of the power tool housing  14  caused by a reactive force  36 , the movable compensating means  30  can execute a compensatory motion in the opposite direction. 
     Expansions and/or alternative embodiments of the exemplary embodiment of  FIG. 10  are obtained by varying the fastening of the cable ends  76 ,  80 , in particular with fastening hooks, fastening leadthroughs, and/or similar fastening elements. Modifications by varying the number of deflection rollers  70 , in particular one, three, four or more deflection rollers  70 , and/or by varying the cable guidance are furthermore possible. 
     If a Bowden cable and/or a traction-thrust chain is used as the traction element  74 , then a restoring element  82  can be dispensed with. 
     A deflection system  20  (not enumerated here) according to the invention with a cable pull device  68  analogous to the exemplary embodiment of  FIG. 10  can also be used for disposing the movable compensating means  30  in the power tool housing and/or can be obtained with other forms of handles and/or fastenings, especially with a second spring element  19  as in  FIG. 2 , for example, as a variation of the example in  FIG. 10 . 
     In  FIG. 11 , a further exemplary embodiment of a handheld power tool of the invention is shown, with a deflection system that is constructed as a pressure hull system  86 . In the embodiment shown here, the pressure hull system  86  is disposed in the handle  16  (not enumerated here. The pressure hull system  86  has a storage cylinder  90  and a pressure line  92 . The pressure hull system further includes a compensation cylinder. The storage cylinder  90  encloses a storage volume  96 . The compensation cylinder includes a compensation volume  98 . The storage volume  96  and the compensation volume  98  communicate with one another via the pressure line  92 , and the total volume is filled with a fluid  100 , preferably a gas or a liquid, in particular hydraulic oil. 
     The storage volume  96  is defined on one side by an axially displaceable storage piston  102 . The first lever arm  22  (not enumerated here) is connected to the storage piston  102 , preferably solidly and in particular in one piece. 
     The compensation volume  98  is defined on one side by an axially displaceable compensation piston  104 . It is connected solidly, preferably rigidly, to the movable compensating means  30  (not enumerated here). In a preferred embodiment, the compensation piston  104  is made in one piece with the movable compensating means  30 . 
     On the side of the compensation piston  104  diametrically opposite the compensation volume  98 , there is a preferably air-filled ventilation volume  106 . This volume communicates with the environment via a throttle restriction  108 . 
     If a reactive force  36  is exerted via the power tool housing  14  on the first lever arm  22  and thus on the storage piston  102 , then the fluid located in the storage volume  96  is compressed and positively displaced. The fluid escapes into the compensation volume  98  via the pressure line  92 . As a result, the compensation piston  104  and thus the movable compensating means are displaced counter to the direction of motion of the power tool housing  14  (not enumerated here). The end located in the decreasing ventilation volume  106  can escape via the throttle restriction  108 . Analogously, a reversal of motion of the movable compensating means  30  relative to the power tool housing  14  ensues in the event that a negative reactive force  36  acts on the power tool housing  14 . 
     By the choice of a suitable fluid  100 , in particular a gas—such as air—or a liquid—such as an oil—the damping action of a vibration damper according to the invention can be varied. Additional influence on the damping properties can be exerted by way of the dimensioning of the volumes  96 ,  98 ,  106  and of the pressure line  92 . Furthermore, by the disposition of a throttle restriction in the pressure line  92 , in particular a variable throttle restriction in the line, the damping can be varied. Finally, there is an additional tuning parameter in the dimensioning of the throttle restriction  108 . In particular, the throttle restriction  108  can be designed variably in such a way that control of the damping characteristic by the user is possible. 
     Alternative embodiments of the exemplary embodiment of  FIG. 11  are obtained among other ways by means of a disposition in the power tool housing. Combinations with other exemplary embodiments are also conceivable; in particular, additionally at least one restoring element  48  and/or damping element  50  that acts on the movable compensating means  30  can be integrated. 
     Further advantageous inventive variants can be obtained by dividing up the movable compensating means  30  into preferably two, three, four or more pressure elements that are embodied in particular as counterweights. 
     The foregoing relates to the preferred exemplary embodiments 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.