Patent Publication Number: US-10315298-B2

Title: Impact mechanism device

Description:
This application claims priority under 35 U.S.C. § 119 to patent application no. DE 10 2013 212 753.7, filed on Jun. 28, 2013 in Germany, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     There has already been proposed an impact mechanism device for a hand power tool, comprising at least one impact mechanism, which has at least one driven cylinder and at least one piston that is driven in an axial direction by the cylinder, via a cam mechanism, and comprising at least one planetary gearing, via which the cylinder and the piston of the impact mechanism can be driven. 
     SUMMARY 
     The disclosure is based on an impact mechanism device for a hand power tool, comprising at least one impact mechanism, which has at least one driven cylinder and at least one piston that is driven in an axial direction by the cylinder, via a cam mechanism, and comprising at least one planetary gearing, via which the cylinder and the piston of the impact mechanism can be driven. 
     It is proposed that the piston of the impact mechanism be disposed at least partially inside the driven cylinder. A “hand power tool” is to be understood to mean, in particular, a machine that performs work on workpieces, but advantageously a rotary hammer and/or percussion hammer and/or a multifunction tool. An “impact mechanism” in this case is to be understood to mean, in particular, a device provided to generate percussion impulses, which are transmitted to a tool clamped in a tool receiver in order to convert a chiseling or hammer drilling operating mode, the impact mechanism being provided to convert a rotary motion into a linear impact motion. The impact mechanism in this case preferably has a piston that, by means of an axial motion, generates a pressure impulse inside the hammer tube of the impact mechanism, the pressure impulse being taken up by an impact element and transmitted to the tool fastened in the tool receiver. A “driven cylinder” in this case is to be understood to mean an element that, at least substantially, has a hollow-cylinder cross section and that is driven rotationally about its central axis. A “cam mechanism” in this case is to be understood to mean, in particular, a device for converting a rotational motion into a linear motion. The linear motion in this case is preferably oriented in the axial direction. The cam mechanism in this case comprises a guide element, which is preferably realized as a groove, and a form closure element, which is in form-closed contact with the cam element for the purpose of guidance. An “axial direction” in this case is to be understood to mean, in particular, a direction that is parallel to a main direction of rotation of a tool clamped in a tool receiver. A “planetary gearing” in this context is to be understood to mean, in particular, a toothed wheel gearing having a sun gear, a planet carrier, at least one planet gear that is carried on a circular orbit around the sun gear by the planet carrier, and having a ring gear that meshes radially outwardly with the at least one planet gear. “At least partially inside” in this case is to be understood to mean, in particular, that at least a part of the piston is disposed inside the cylinder. It is thereby possible to achieve an impact mechanism device that is advantageously short in the axial direction, thus making it possible, in particular, to provide a particularly advantageously compact hand power tool. 
     Further, it is proposed that the piston be realized as a hollow piston, which is moved axially to generate a pressure impulse. A “hollow piston” in this case is to be understood to mean, in particular, a piston having a basic shape of a hollow cylinder, the piston being open on one axial side and closed on an opposite side. An axial motion of the piston causes a pressure impulse to be generated inside the piston, which pressure impulse encounters an element disposed inside the piston, such as, in particular, a striker of the impact mechanism, which takes up the pressure impulse and transmits it, directly or via further intermediate elements, to a tool in the tool receiver. As a result, particularly advantageously, the piston can be realized for a short impact mechanism structure. 
     It is additionally proposed that the piston have, on its outer circumference, an outer curve that realizes the piston-side cam mechanism. An “outer curve” in this case is to be understood to mean, in particular, a guide path disposed on an outer circumference of the piston, the guide path preferably being realized as a groove. As a result, the cam mechanism can be realized in a particularly advantageous manner. 
     Furthermore, it is proposed that the piston have, on its outer circumference, a further outer curve that, together with the one outer curve, realizes the piston-side cam mechanism. A “further outer curve” in this case is to be understood to mean, in particular, an outer curve realized so as to be identical in its course to the other outer curve of the piston-side cam mechanism, only disposed in an offset manner in the circumferential direction on the outer circumference of the piston. The outer curves in this case are preferably disposed in a non-uniformly distributed manner on the circumference. The outer curves in this case are distributed on the circumference at an angular distance of other than 180 degrees. As a result, forces can be apportioned advantageously to the outer curves and to the form closure elements engaging in the outer curves, and consequently reduced for each individual element, enabling a service life of the impact mechanism device to be increased in a particularly advantageous manner. 
     It is further proposed that the outer curve and the further outer curve be distributed in a non-uniform manner on the outer circumference of the piston. “Distributed in a non-uniform manner on the circumference” is to be understood to mean, in particular, that the outer curves at an axial position in a first circumferential direction are at a different distance from each other than in an opposite, second circumferential direction. The outer curves in this case have, in particular, an angular distance from each other that is other than 180 degrees. As a result, particularly advantageously, it is possible to prevent a collision of form closure elements engaging in the different outer curves. 
     Moreover, it is proposed that the piston be composed of a first, lighter material, and the outer curve be composed of a second, harder material. A “first, lighter material” in this case is to be understood to mean, in particular, a light metal, a plastic, or another light material considered appropriate by persons skilled in the art. A “harder material” in this case is to be understood to mean, in particular, a material that is harder and more wear resistant than the first material. In this case, the “second, harder material” is to be understood to mean, in particular, a material that has been hardened, or that has been coated to increase wear resistance, and that, in particular, has a greater hardness. As a result, the piston can be made particularly light and, at the same time, particularly advantageously, the curved path can be particularly wear resistant, thus making it possible, in particular, to achieve advantageous quietness of running and a particularly advantageous wear behavior of the impact mechanism device. 
     It is furthermore proposed that the cylinder have at least one form closure element, which engages in the outer curve for the purpose of guiding the piston. As a result, the cam mechanism can be realized in a particularly advantageous manner. 
     Further, it is proposed that the cylinder be driven via a first output of the at least one planetary gearing, and the piston be driven via a second output of the at least one planetary gearing. An “output of a planetary gearing” in this case is to be understood to mean, in particular, an element of the planetary gearing such as, in particular, a sun gear, a ring gear or a planet carrier, via which a moment is diverted out of the planetary gearing. As a result, the impact mechanism device can be realized in a particularly advantageous manner, and a differential rotational speed can be achieved between the piston and the cylinder. 
     Moreover, it is proposed that the first output, via which the cylinder is driven, be realized as a sun gear of the second planetary gearing. As a result, the impact mechanism device can be realized in a particularly advantageously compact manner. 
     Furthermore, it is proposed that the impact mechanism device comprise at least one switching device, which is provided for mechanical switching of various operating modes. “Mechanical switching” in this case is to be understood to mean, in particular, switching that is preferably effected purely mechanically, i.e. in which a force and/or a movement initiated by an operator is taken up by a mechanism and a switching operation is converted by a movement of the mechanism, the mechanical switching, in particular, not making use of an electronic component. In this way, particularly advantageously, various operating modes can be switched by an operator. 
     In addition, it is proposed that the switching device comprise at least one slide sleeve, which has form closure elements for coupling to a tool receiver and for actuating a coupling point of the switching device for the purpose of coupling the piston. A “slide sleeve” in this case is to be understood to mean, in particular, a sleeve that is mounted so as to be axially displaceable and that, because of its design, switches differing operating states in differing positions. As a result, the various operating states can be switched particularly easily. 
     Further, it is proposed that the coupling point of the switching device comprise radially displaceable form closure elements, which are optionally held in a form closure or released by the slide sleeve, for the purpose of coupling and decoupling the piston. “Decoupling the piston” in this case is to be understood to mean, in particular, undoing a rotationally fixed connection between the piston and a drive, such that the piston is no longer driven rotationally. “Coupling the piston” in this case is to be understood to mean, in particular, establishing a rotationally fixed connection between the piston and a drive, such that the piston is driven rotationally. As a result, a percussive operating mode of the impact mechanism can be switched particularly easily and rapidly. 
     It is further proposed that the impact mechanism device have a mechanical switchover unit, which, for the purpose of switching over a direction of rotation of a tool receiver, is provided to fix optionally a ring gear or a planet carrier of the second planetary gearing. The term “to fix” in this case is to be understood to mean, in particular, to connect to a housing element in a rotationally fixed manner. As a result, a direction of rotation of a tool that is clamped in the tool receiver can be switched over by an operator in an advantageously simple and rapid manner. 
     The impact mechanism device according to the disclosure is not intended in this case to be limited to the application and embodiment described above. In particular, the impact mechanism device according to the disclosure may have individual elements, components and units that differ in number from a number stated herein, in order to fulfill a principle of function described herein. 
     Further advantages are given by the following description of the drawings. The drawings show five exemplary embodiments of the disclosure. The drawing, the description and the claims contain numerous features in combination. Persons skilled in the art will also expediently consider the features individually and combine them to create appropriate further combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  shows a hand power tool comprising an impact mechanism device according to the disclosure, in a first exemplary embodiment, 
         FIG. 2  shows a cylinder and a piston of an impact mechanism device according to the disclosure, in a first exemplary embodiment, 
         FIG. 3  shows a schematic representation of an impact mechanism device, in a second exemplary embodiment, 
         FIG. 4  shows a portion of a switching device of the impact mechanism device, in the second exemplary embodiment, 
         FIG. 5  shows a schematic representation of an impact mechanism device, in a third exemplary embodiment, and 
         FIG. 6  shows a schematic representation of an impact mechanism device, in a fourth exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show a hand power tool  10   a , comprising an impact mechanism device according to the disclosure, in a first exemplary embodiment. The hand power tool  10   a  is realized as a rotary hammer. The hand power tool  10   a , realized as a rotary hammer, has a pistol-shaped machine housing  54   a , in which the impact mechanism device according to the disclosure is disposed. A handle  56   a , which comprises an operating element, is disposed on the machine housing  54   a . The hand power tool  10   a  can be actuated via the operating element. It is also conceivable in principle for the hand power tool  10   a  to have a machine housing of a different design, considered appropriate by persons skilled in the art. For the purpose of driving the hand power tool  10   a , the hand power tool  10   a  comprises a drive unit  58   a . The drive unit  58   a  in this case is realized as an electric motor. It is also conceivable in principle for the drive unit  58   a  to be realized as a different drive unit  58   a , considered appropriate by persons skilled in the art. In this case, the drive unit  58   a  is merely indicated in  FIG. 1 . The hand power tool  10   a  comprises a drive shaft  60   a , which is driven rotationally by the drive unit  58   a . The hand power tool  10   a  comprises a tool receiver  38   a , which is disposed at a front end of the hand power tool  10   a . The tool receiver  38   a  is provided to receive a tool. The tool in this case may be realized as a chisel or, for example, as a drill bit. 
     The impact mechanism device is provided to drive the tool receiver  38   a , and in particular a tool clamped in the tool receiver  38   a . The impact mechanism device comprises an impact mechanism  12   a . The impact mechanism  12   a  in this case is provided to transmit an impulse to the tool mounted in the tool receiver  38   a . For this purpose, the impact mechanism  12   a  comprises an impact element  62   a , which is mounted so as to be axially displaceable in relation to the tool receiver  38   a , and which is provided to transmit an impulse to the tool mounted in the tool receiver  38   a . The impact element  62   a  in this case is provided to transmit a pneumatic pressure impulse, acting upon one side of the impact element  62   a , to the tool. In order to generate the pneumatic pressure impulse, the impact mechanism  12   a  has a piston  16   a . The piston  16   a  is provided to generate the pneumatic pressure impulse that acts upon the impact element  62   a , by means of an axial motion. The piston  16   a  in this case is realized as a hollow piston. The piston  16   a  has a hollow-cylinder basic body. In this case, a central recess in the piston  16   a  is open on one axial side, and closed on an opposite axial side. The recess in the piston  16   a , which realizes the piston  16   a  as a hollow piston, is realized as a blind hole. The piston  16   a  is open at a first end and closed by a wall  64   a  at a second end. In this case, in a mounted state, the first end, at which the recess is open, is aligned in the direction of the tool receiver  38   a , i.e. in a front region of the hand power tool  10   a . The impact element  62   a  in this case is disposed inside the piston  16   a  that is realized as a hollow piston. The impact element  62   a  in this case projects from the first end into the recess of the hollow piston. In this case, the impact element  62   a  is disposed so as to be axially movable inside the piston  16   a . The impact element  62   a  in this case realizes a sealing element  66   a  at a first end, which faces away from the tool receiver  38   a . The sealing element  66   a  bears against an inner wall  68   a  of the piston  16   a  realized as a hollow piston, and thereby seals off a pressure chamber between the wall  64   a , which delimits the recess of the piston  16   a , and the sealing element  66   a . The piston  16   a  in this case is composed of a first, light material. The piston  16   a  in this case is composed of a light metal, in particular an aluminum. Clearly, it is also conceivable in principle for the piston  16   a  to be composed of another material, considered appropriate by persons skilled in the art, such as, for example, another metal such as, in particular, another light metal or plastic. 
     For the purpose of driving the piston  16   a  in the axial direction, i.e. for the purpose of generating the pressure impulse by means of the piston  16   a , the impact mechanism  12   a  has a cylinder  14   a . The cylinder  14   a  is realized as a hollow cylinder, which is closed on one side by a wall. The cylinder  14   a  is provided to move the piston  16   a  back and forth axially. The impact mechanism device comprises a cam mechanism  18   a , for driving the piston  16   a  axially. The piston  16   a  in this case is driven in the axial direction by the cylinder  14   a , via the cam mechanism  18   a . For the purpose of realizing the cam mechanism  18   a  on the piston side, the piston  16   a  has a first outer curve  24   a  on its outer circumference. The first outer curve  24   a  is realized as a groove made in the outside of the piston  16   a . In this case, the groove constituting the first outer curve  24   a  has a semicircular cross section. Owing to the semicircular cross section, unfavorable notch effects can be reduced, as compared with a rectangular cross section. For the purpose of realizing the cam mechanism  18   a  on the piston side, the piston  16   a  has a second outer curve  26   a . The second outer curve  26   a  is likewise constituted by a groove. In this case, the groove is identical in form to the groove constituting the first outer curve  24   a . The first outer curve  24   a  and the second outer curve  26   a  each have a course that is identical to the other. The first outer curve  24   a  and the second outer curve  26   a  are disposed in an offset manner on the outer circumference of the piston  16   a . In this case, the outer curves  24   a ,  26   a  are distributed in a non-uniform manner on the outer circumference of the piston  24   a . On the outer circumference of the piston  16   a , the outer curves  24   a ,  26   a  have an angular distance from each other that is other than 180 degrees. The outer curves  24   a ,  26   a  realize a wave shape, aligned in the axial direction, on the outer circumference. The outer curves  24   a ,  26   a  in this case each realize a sine shape. However, it is also conceivable in principle for the outer curves  24   a ,  26   a  to have a wave shape other than a sine shape. The outer curves  24   a ,  26   a  in this case are composed of a second, harder material. In this case, the outer curves  24   a ,  26   a  are composed of a hardened material. It is conceivable in this case for the outer curves and the piston to be produced in a multicomponent process. Owing to the second, harder material, the outer curves  24   a ,  26   a  are realized so as to be more resistant to wear than a remainder of the piston  16   a . It is also conceivable in principle in this case for the outer curves  24   a ,  26   a  to have a coating by which the outer curves  24   a ,  26   a  are made more resistant to wear. It is also conceivable in principle for the outer curves  24   a ,  26   a  to be made harder than the rest of the piston  16   a  in another way, considered appropriate by persons skilled in the art. The cam mechanism  18   a  comprises two form closure elements  50   a ,  52   a , which are each provided for guidance in an outer curve  24   a ,  26   a  of the piston  16   a . The form closure elements  50   a ,  52   a  are realized as pins. The form closure elements  50   a ,  52   a  in this case are fixedly connected to the cylinder  14   a  of the impact mechanism device. The form closure elements  50   a ,  52   a  are fixedly disposed at a position on the cylinder  14   a . For the purpose of fastening the form closure elements  50   a ,  52   a , the cylinder  14   a  has a radially extending through hole  70   a  in each case. The form closure elements  50   a ,  52   a  in this case are each respectively disposed in one of the through holes  70   a , and thereby connected to the cylinder  14   a  in a stationary manner, but having play and being rotatable. The form closure elements  50   a ,  52   a  are each fixedly disposed in the through holes  70   a  by means of press fits. In a mounted state, the form closure elements  50   a ,  52   a  project inwardly into the cylinder  14   a . In a mounted state, the form closure elements  50   a ,  52   a  are disposed in the outer curves  24   a ,  26   a  of the piston  16   a  by an inner region projecting inwardly into the cylinder  14   a . As a result, the piston  16   a  is guided in a constrained manner in relation to the cylinder  14   a  by means of the form closure elements  50   a ,  52   a  and the outer curves  24   a ,  26   a . Upon a relative rotation between the cylinder  14   a  and the piston  16   a , the piston  16   a  is moved axially back and forth inside the cylinder  14   a  by the cam mechanism  18   a.    
     For the purpose of transmitting a rotational speed and a torque from the drive unit  58   a  to the impact mechanism  12   a , the impact mechanism device comprises a first planetary gearing  72   a.  The first planetary gearing  72   a  comprises a sun gear  74   a , three planet gears  76   a  that mesh radially outwardly on the sun gear  74   a , a planet carrier  78   a , which carries the planet gears  76   a  in a rotatable manner in each case, and a ring gear  80   a , which is disposed radially outside of the planet gears  76   a , and which meshes with the planet gears  76   a . The sun gear  74   a  is connected in a rotationally fixed manner to the drive shaft  60   a , which is directly driven by the drive unit  58   a . Via the sun gear  74   a , a rotation is introduced into the first planetary gearing  72   a . The ring gear  80   a  of the first planetary gearing  72   a  is connected in a rotationally fixed manner to a housing element  82   a  of the machine housing  54   a , i.e. is stationary. It is also conceivable in principle for the ring gear  80   a  of the first planetary gearing  72   a  to be directly connected in a rotationally fixed manner to the machine housing  54   a . The planet carrier  78   a  of the first planetary gearing  72   a  realizes an output of the first planetary gearing  72   a , via which a rotation is diverted out of the first planetary gearing  72   a . The impact mechanism device in this case comprises a rolling bearing  84   a , by means of which the planet carrier  78   a  is realized so as to be rotatable in relation to the housing element  82   a . The planet carrier  78   a  extends from a rolling plane, on which the planet gears  76   a , the sun gear  74   a  and the ring gear  80   a  mesh with each other, in the direction of the tool receiver  38   a  and away from the drive unit  58   a . The impact mechanism device comprises a second planetary gearing  22   a . The second planetary gearing  22   a  is positioned after the first planetary gearing  72   a , as viewed from the drive unit  58   a . The second planetary gearing  22   a , as also the first planetary gearing  72   a , has a sun gear  28   a , three planet gears  86   a  that mesh radially outwardly on the sun gear, a planet carrier  48   a , which carries the planet gears  86   a  in a rotatable manner in each case, and a ring gear  46   a , which is disposed radially outside of the planet gears  86   a , and which meshes with the planet gears  86   a . The sun gear  28   a  of the second planetary gearing  22   a  realizes an input of the second planetary gearing  22   a . The sun gear  28   a  of the second planetary gearing  22   a  is connected in a rotationally fixed manner to the planet carrier  78   a  of the first planetary gearing  72   a . The sun gear  28   a  of the second planetary gearing  22   a  is also realized as a first output of the second planetary gearing  22   a , and realized to drive the impact mechanism  12   a . The ring gear  46   a  of the second planetary gearing  22   a  is connected in a rotationally fixed manner to the housing element  82   a  of the machine housing  54   a , i.e. is stationary. It is also conceivable in principle for the ring gear  46   a  of the second planetary gearing  22   a  to be directly connected in a rotationally fixed manner to the machine housing  54   a . The planet carrier  48   a  of the second planetary gearing  22   a  is realized as a second output of the second planetary gearing  22   a , and likewise provided to drive the impact mechanism  12   a.    
     For the purpose of driving the impact mechanism  12   a , the first output of the second planetary gearing  22   a  is coupled in a rotationally fixed manner to the cylinder  14   a  of the impact mechanism  12   a . The sun gear  28   a  of the second planetary gearing  22   a  is connected in a rotationally fixed manner to the cylinder  14   a  of the impact mechanism  12   a . It would also be conceivable in principle for the cylinder  14   a  of the impact mechanism  12   a  to constitute a single piece with the sun gear  28   a  of the cylinder  14   a . The second output, i.e. the planet carrier  48   a  of the second planetary gearing  22   a , is connected in a rotationally fixed manner to the piston  16   a  of the impact mechanism  12   a . If the first output, i.e. the sun gear  28   a , and the second output, i.e. the planet carrier  48   a , have differing rotational speeds, a differential rotational speed ensues between the cylinder  14   a  and the piston  16   a , as a result of which the cam mechanism  18   a  generates axial driving of the piston  16   a  inside the cylinder  14   a . If the second planetary gearing  22   a  is in an unblocked state, the sun gear  28   a , i.e. the first output, and the planet carrier  48   a  always have differing rotational speeds. The tool receiver  38   a  is likewise driven via the second output, i.e. the planet carrier  48   a  of the planetary gearing  22   a . In this case, the second output, i.e. the planet carrier  48   a  of the planetary gearing  22   a , drives the tool receiver  38   a  rotationally, causing a tool that is present in the tool receiver  38   a  to rotate. In this case, a coupling point, not represented in greater detail in  FIG. 1 , is integrated between the planet carrier  48   a  of the planetary gearing  22   a  and the tool receiver  38   a , by means of which coupling point a rotationally fixed connection between the planet carrier  48   a  of the second planetary gearing  22   a  and the tool receiver  38   a  can optionally be made or undone. The coupling point can be used to switch on or switch off a drilling operating mode of the hand power tool  10   a . For the purpose of deactivating an impact operating mode, in which the impact mechanism  12   a  impacts on the tool clamped in the tool receiver  38   a , either in addition to a rotation or exclusively, the impact mechanism device has a further coupling point, not represented in greater detail in  FIG. 1 . The coupling point may be provided, for example, to block the second planetary gearing  22   a . As a result of blocking of the second planetary gearing  22   a , the sun gear  28   a  and the planet carrier  48   a , i.e. the first output and the second output of the second planetary gearing  22   a , rotate at the same rotational speed, such that there would be no relative rotational speed between the cylinder  14   a  and the piston  16   a , as a result of which the axial movement of the piston  16   a  inside the cylinder  14   a  is prevented by the cam mechanism  18   a.    
     Further exemplary embodiments of the disclosure are shown in  FIGS. 3 to 6 . The descriptions that follow and the drawings are each limited substantially to the differences between the exemplary embodiments, and in principle reference may also be made to the drawings and/or to the description of the other exemplary embodiments, in particular of  FIGS. 1 and 2 , in respect of components having the same designation, in particular relating to components having the same references. To distinguish the exemplary embodiments, the letter a has been appended to the references of the exemplary embodiment in  FIGS. 1 and 2 . In the exemplary embodiments of  FIGS. 3 to 6 , the letter a has been replaced by the letters b, d, e. 
       FIGS. 3 and 4  show a second exemplary embodiment of an impact mechanism device according to the disclosure.  FIGS. 3 and 4  show a hand power tool  10   b  comprising the impact mechanism device according to the disclosure. Unlike the first exemplary embodiment, the hand power tool  10   b , realized as a rotary hammer, has a differently designed machine housing  54   b , in which the impact mechanism device according to the disclosure is disposed. The machine housing  54   b  is realized in an L-shaped design. In a manner similar to the first exemplary embodiment, the impact mechanism device likewise has a second planetary gearing  22   b , a drive unit  58   b , and an impact mechanism  12   b  comprising a piston  16   b  and a cylinder  14   b . For the purpose of driving the piston  16   b , the impact mechanism device in this case has a cam mechanism  18   b , which drives the piston  16   b  via the cylinder  14   b . The second planetary gearing  22   b , and the cylinder  14   b  and the piston  16   b , are realized in a manner that is substantially equivalent to the first exemplary embodiment. 
     The impact mechanism device comprises a switching device  30   b  for switching various operating modes of the hand power tool  10   b . Three operating modes, namely chiseling, hammer drilling and drilling, can be switched by means of the switching device  30   b . In this case, the switching device  30   b  is realized as a mechanical switching device  30   b . The various operating modes can be adjusted in a purely mechanical manner by means of the switching device  30   b . The switching device  30   b  comprises a slide sleeve  32   b , which is disposed in a front region of the piston  16   b , at a transition to a tool receiver  38   b . In this case, the slide sleeve  32   b  is disposed radially outside of a driver element  88   b , via which the piston  16   b  can be driven by a second output of the second planetary gearing  22   b . The driver element  88   b  is realized as a hollow cylinder, which is disposed radially outside of the piston  16   b . The driver element  88   b  is connected in a rotationally fixed manner to the second output of the second planetary gearing  22   b . The slide sleeve  32   b  is axially displaceable in this case. For the purpose of switching the three operating modes, the slide sleeve  32   b  has three switching positions. Each of the three switching positions is represented in this case by an axial position of the slide sleeve  32   b  on the driver element  88   b . The slide sleeve  32   b  is connected in a rotationally fixed manner to the driver element  88   b . The driver element  88   b  comprises form closure elements  138   b , via which the slide sleeve  32   b  is connected in a form-closed manner to the driver element  88   b . The slide sleeve  32   b  has form closure elements  92   b , which are realized to correspond to the form closure elements  138   b . For the purpose of connecting the slide sleeve  32   b  in a rotationally fixed manner, the form closure elements  138   b  of the driver element  88   b  and the form closure elements  92   b  of the slide sleeve  32   b  engage in each other in a form-closed manner. It is conceivable in this case for the form closure elements  92   b ,  138   b  to be realized as a toothing. As a result, the slide sleeve  32   b  can only be displaced axially on the driver element  88   b , but not turned in relation to the latter. The slide sleeve  32   b  projects beyond the driver element  88   b  in the direction of the tool receiver  38   b . On a side that faces toward the driver element  88   b , the tool receiver  38   b  has a plurality of form closure elements  90   b , which are provided for coupling to the slide sleeve  32   b . The form closure elements  90   b  in this case are realized as protrusions disposed in a distributed manner on a circumference of the tool receiver  38   b , which protrude radially outward. It is also conceivable in principle for the form closure elements  90   b  to be realized as teeth of a toothing disposed on the circumference of the tool receiver  38   b . The form closure elements  92   b  of the slide sleeve  32  are likewise realized to correspond to the form closure elements  90   b  of the tool receiver  38   b . If the tool receiver  38   b  and the slide sleeve  32   b  are connected to each other via their form closure elements  90   b ,  92   b , the tool receiver  38   b  and the slide sleeve  32   b  are coupled to each other in a rotationally fixed manner. In this case, a rotation introduced into the slide sleeve  32   b  via the driver element is transmitted to the tool receiver  38   b , and a tool clamped in the tool receiver  38   b  rotates. In the first switching position and in a second switching position, the form closure elements  92   b  of the slide sleeve  32   b  engage in the form closure elements  90   b  of the tool receiver. As a result, the tool receiver  38   b  is driven rotationally in the first and in the second switching position of the slide sleeve  32   b . In the third switching position of the slide sleeve  32   b , the form closure elements  92   b  of the slide sleeve  32   b  are separated from the form closure elements  90   b  of the tool receiver  38   b , as a result of which a rotationally fixed coupling of the tool receiver  38   b  and the slide sleeve  32   b  is disconnected. In this case, the first switching position is realized as a position of the slide sleeve  32   b  shifted maximally in the direction of the tool receiver  38   b . The second switching position is realized as a middle position of the slide sleeve  32   b . Accordingly, the third switching position of the slide sleeve  32   b  is realized as position of the slide sleeve  32   b  that is maximally in the direction of the second planetary gearing  22   b , i.e. maximally distant from the tool receiver  38   b.    
     For the purpose of deactivating an impact operating mode of the impact mechanism  12   b , the switching device  30   b  comprises a coupling point  40   b . The coupling point  40   b  is provided for separably coupling the piston  16   b  and the river element  88   b . For this purpose, the piston  16   b  has, on a region that faces toward the driver element  88   b , a plurality of form closure elements  94   b  disposed on an offset outer circumference. The form closure elements  94   b  in this case are realized as protrusions, which extend radially outward from the outer circumference of the piston  16   b . For the purpose of coupling to the form closure elements  94   b  of the piston  16   b , the coupling point  40   b  has radially displaceable form closure elements  42   b . The radially displaceable form closure elements  42   b  are realized as balls, which are each disposed in a radially extending through recess  96   b  in the driver element  88   b . It is also conceivable in principle for the form closure elements  42   b  coupled to the driver element  88   b  to be realized, for example, as pins. The form closure elements  42   b  coupled to the driver element  88   b  each have two switching positions. In a first switching position, the form closure elements  42   b  project radially inward into the driver element  88   b , and in this case they come into form-closed contact with the form closure elements  94   b  of the piston  16   b  and thus couple the piston  16   b  in a rotationally fixed manner to the driver element  88   b . As a result, in a first switching position of the form closure elements  42   b , the piston  16   b  rotates at a rotational speed of the driver element  88   b , and a differential rotational speed between the piston  16   b  and the cylinder  14   b  causes the piston  16   b  to be moved axially back and forth in an impact motion, by means of the cam mechanism  18   b . In this case, the form closure elements  42   b , by a radially outer end, bear against a radial inside  98   b  of the slide sleeve  32   b . As a result, the form closure elements  42   b  are held in a form closure in the first position by the slide sleeve  32   b . In this case, in the second and third switching positions of the slide sleeve  32   b , the form closure elements  42   b  are held by the slide sleeve  32   b  in the first switching position. As a result, an impact operating mode of the impact mechanism  12   b  is activated in the second and third switching positions of the slide sleeve  32   b.  For the purpose of deactivating the impact operating mode of the impact mechanism  12   b , the slide sleeve  32   b  has a recess  100   b  each form closure element  42   b  coupled to the driver element  88   b , the recesses  100   b  being disposed on the radial inside  98   b  of the slide sleeve  32   b . The recesses  100   b  in this case are all made at the same axial position in the inside  98   b  of the slide sleeve  32   b . In the first switching position of the slide sleeve  32   b , the recesses  100   b  are congruent with the radially displaceable form closure elements  42   b  coupled to the driver element  88   b . As a result, the form closure elements  42   b  coupled to the driver element  88   b  in the first switching position of the slide sleeve  32   b  slide radially outward into their second switching position, into the congruently disposed recesses  100   b  in the inside  98   b  of the slide sleeve  32   b . In this case, the form closure elements  42   b  are driven radially outward into the recesses  100   b  by the centrifugal forces that occur upon a rotation of the driver element  88   b . In the second switching position of the form closure elements  42   b , in which they are disposed in the respective recesses  100   b , the form closure elements  42   b  are separated from the form closure elements  94   b  of the piston  16   b . A form-closed connection between the form closure elements  94   b  of the piston  16   b  and the form closure elements  42   b  coupled to the driver element  88   b  is undone in the second switching position of the form closure elements  42   b , which go into the first switching position of the slide sleeve  32   b , as a result of which a rotationally fixed coupling of the piston  16  to the driver element  88   b  is undone. The slide sleeve  32   b , in its first switching position, releases the form closure elements  42   b.    
     In the first switching position of the slide sleeve  32   b , the tool receiver  38   b  is connected in a rotationally fixed manner to the slide sleeve  32  via the form closure elements  90   b ,  92   b . The form closure elements  42   b  coupled to the driver element  88   b  are disposed in the respective recesses  100   b  of the slide sleeve  32   b  and separated from the form closure elements  94   b  of the piston  16   b . The first switching position of the slide sleeve  32   b  thereby generates the operating mode of drilling, in which only the tool receiver  38   b  rotates, but no impact pulse is generated by the impact mechanism  12   b . In the second switching position of the slide sleeve  32   b , the tool receiver  38   b  is connected in a rotationally fixed manner to the slide sleeve  32  via the form closure elements  90   b ,  92   b . The form closure elements  42   b  coupled to the driver element  88   b  are pressed radially inward, via the inside  98   b  of the slide sleeve  32   b , and are in form-closed contact with the form closure elements  94   b  of the piston  16   b , such that the piston  16   b  is coupled in a rotationally fixed manner to the driver element  88   b . As a result, the second, middle switching position of the slide sleeve  32   b  generates the operating mode of hammer drilling, in which the tool receiver  38   b  rotates and an impact pulse is additionally generated by the impact mechanism  12   b . In the third switching position of the slide sleeve  32 , the tool receiver  38   b  is separated from the slide sleeve  32 . The form closure elements  92   b  of the slide sleeve  32   b  are separated from the form closure elements  90   b  of the tool receiver  38   b . In the third switching position of the slide sleeve  32 , the form closure elements  42   b  coupled to the driver element  88   b  are pressed radially inward, via the inside  98   b  of the slide sleeve  32   b , and are in form-closed contact with the form closure elements  94   b  of the piston  16 , such that the piston  16  is coupled in a rotationally fixed manner to the driver element  88   b . As a result, the third switching position of the slide sleeve  32   b  generates the operating mode of chiseling, in which the tool receiver  38   b  does not rotate, and only an impact pulse is generated by the impact mechanism  12   b . The switching device  30   b  in this case comprises an actuating element  102   b , by means of which an operator can manually switch the slide sleeve  32   b  into the various switching positions. The actuating element  102   b  is realized as a sleeve, which encompasses the slide sleeve  32   b . In this case, a lever element of the actuating element  102   b  projects out of the machine housing  54   b , from which it can be contacted and operated by an operator. The slide sleeve  32   b  comprises a driver element  140   b , via which the slide sleeve  32   b  is coupled to the actuating element  102   b . The driver element  140   b  is realized as a protrusion that extends on the outside of the slide sleeve  32   b  and that is in form-closed contact with the driver element for the purpose of coupling to the actuating element  102   b . It is also conceivable in principle for the slide sleeve  32   b  to be displaced directly by an operator. 
       FIG. 5  shows a third exemplary embodiment of an impact mechanism device according to the disclosure. The impact mechanism device is realized in substantially the same manner as the impact mechanism device from the first exemplary embodiment from  FIGS. 1 and 2 . In this case, the impact mechanism device is represented merely schematically here. In a manner similar to the first exemplary embodiment, the impact mechanism device likewise has a second planetary gearing  22   d , and an impact mechanism  12   d  comprising a piston  16   d  and a cylinder  14   d . The second planetary gearing  22   d , and the cylinder  14   d  and the piston  16   d , are realized in a manner that is substantially equivalent to the first exemplary embodiment. In this case, for the purpose of driving the piston  16   d , the impact mechanism device has a cam mechanism  18   d , which drives the piston  16   d  via the cylinder  14   d.    
     The impact mechanism device comprises a mechanical switchover unit  44   d , by means of which the direction of rotation of a tool, disposed in a tool receiver  38   d , can be reversed. The mechanical switchover unit  44   d  in this case for switching over the direction of rotation is provided to fix optionally a ring gear  46   d  or a planet carrier  48   d  of the second planetary gearing  22   d . The mechanical switchover unit  44   d  comprises a switching sleeve  116   d , which is displaceable in an axial direction  20   d . Mounted on the switching sleeve  116   d  in this case is an actuating element  118   d , by means of which an operator can displace the switching sleeve  116   d  in the axial direction  20   d . The second planetary gearing  22   d  is mounted inside the switching sleeve  116   d . The switching sleeve  116   d  comprises a form closure element  120   d , via which the switching sleeve  116   d  can be coupled in a rotationally fixed manner to the ring gear  46   d  or to the planet carrier  48   d  of the second planetary gearing  22   d . The switching sleeve  116   d  comprises a first switching position and a second switching position. To illustrate the two differing switching positions,  FIG. 5  shows an upper half of the impact mechanism device with the switching sleeve  116   d  in the first switching position and a lower half of the impact mechanism device with the switching sleeve  116   d  in the second switching position. In the first switching position of the switching sleeve  116   d , the planet carrier  48   d  is connected in a rotationally fixed manner to the switching sleeve  116   d , via the form closure element  120   d , and is thereby fixed. The ring gear  46   d  of the second planetary gearing  22   d  can rotate and, via a coupling point  122   d , is connected in a rotationally fixed manner to a driver element  88   d  of the impact mechanism device that is provided for rotationally driving the tool receiver  38   d  and the piston  16   d  of the impact mechanism  12   d . This results in driving of the driver element  88   d , i.e. the tool receiver  38   d  and the piston  16   d , via the ring gear  46   d  of the second planetary gearing  22   d  that, in this switching position, is realized as an output of the second planetary gearing  22   d . For the purpose of switching over into the second switching position, the switching sleeve  116   d  is displaced in the axial direction  20   d , in the direction of the tool receiver  38   d . In the second switching position, the form closure element  120   d  is coupled to the ring gear  46   d  of the second planetary gearing  22   d , and thus fixes the latter. The planet carrier  48   d  of the second planetary gearing  22   d  can rotate and, via a coupling point  124   d , is connected in a rotationally fixed manner to the driver element  88   d  of the impact mechanism device. This results in driving of the driver element  88   d , i.e. the tool receiver  38   d  and the piston  16   d , via the planet carrier  48   d  of the second planetary gearing  22   d  that, in this switching position, is realized as an output of the second planetary gearing  22   d . The switchover of the output of the second planetary gearing  22   d , which in the first switching position is constituted by the ring gear  46   d  and in the second switching position is constituted by the planet carrier  48   d , the planet carrier  48   d  being fixed in the first switching position and the ring gear  46   d  being fixed in the second switching position, causes a direction of rotation of the driver element  88   d  to be reversed, respectively, in both switching positions. As a result, an operator can easily effect mechanical switchover of a direction of rotation of a tool in the tool receiver  38   d.    
       FIG. 6  shows a fourth exemplary embodiment of a impact mechanism device according to the disclosure. The impact mechanism device is realized in substantially the same manner as the impact mechanism device from the first exemplary embodiment from  FIGS. 1 and 2 . In this case, the impact mechanism device is represented merely schematically here. In a manner similar to the first exemplary embodiment, the impact mechanism device likewise has an impact mechanism  12   e  comprising a piston  16   e  and a cylinder  14   e . The second planetary gearing  22   e , and the cylinder  14   e  and the piston  16   e , are realized in a manner that is substantially equivalent to the first exemplary embodiment. In this case, for the purpose of driving the piston  16   e , the impact mechanism device has a cam mechanism  18   e , which drives the piston  16   e  via the cylinder  14   e . The impact mechanism device comprises a gearing device  126   e , by means of which two gears can be switched. In the differing gear, the gearing device  126   e  has respectively differing gear ratios. For the purpose of realizing the gearing device  126   e , the impact mechanism device, as in the first exemplary embodiment from  FIGS. 1 and 2 , has a first planetary gearing  72   e  and the second planetary gearing  22   e . The gearing device  126   e  has a third planetary gearing  128   e , which is disposed between the first planetary gearing  72   e  and the second planetary gearing  22   e . A planet carrier  78   e  of the first planetary gearing  72   e  is coupled to a sun gear  130   e  of the third planetary gearing  128   e . A planet carrier  132   e  of the third planetary gearing  128   e  is coupled in a rotationally fixed manner to a sun gear  28   e  of the second planetary gearing  22   e . A ring gear  134   e  of the third planetary gearing  128   e  is rotatably mounted. The gearing device  126   e  comprises a switching element  136   e , which is provided for blocking the third planetary gearing  128   e . The switching element  136   e  in this case is shown only schematically in  FIG. 6 . In the first switching position of the switching element  136   e , the third planetary gearing  128   e  is unblocked. In the second switching position of the switching element  136   e , the third planetary gearing  128   e  is blocked. For the purpose of blocking the third planetary gearing  128   e , the switching element  136   e  connects the ring gear  134   e  of the third planetary gearing  128   e  in a rotationally fixed manner to the sun gear  130   e  of the third planetary gearing  128   e . As a result, the third planetary gearing  128   e  is blocked and, as it were, bridged. A rotational speed is no longer converted in the third planetary gearing  128   e . For the same input rotational speed, via the sun gear  130   e , the planet carrier  132   e , in a first switching position of the switching element  136   e , has a different rotational speed than in the second switching position of the switching element  136   e.    
     It is also conceivable in principle for the gearing device  126   e  to be designed in a different manner, considered appropriate by persons skilled in the art, for switching various gear speeds in the hand power tool  10   e . It is thus conceivable, for example, for only two planetary gearings  22   e ,  72   e  to be provided for switching various gear speeds, and for switching of the various gear speeds to be effected by releasing and holding either the ring gear or the planet carrier of the corresponding planetary gearing  22   e ,  72   e.    
     It is also to be noted here, in principle, that the differing exemplary embodiments may also be combined in a common hand power tool  10 . It is thus conceivable, for example, for switching of the operating modes from the second exemplary embodiment to be combined with the gearing device from the fifth exemplary embodiment. Further combinations are likewise conceivable.