Abstract:
A hand-held machine tool has an integrated tool or a tool holder to receive a tool. An electric motor drives the tool or the tool holder. A battery pack for supplying power to the electric motor can be pushed into a guide in a first direction. Electrical contacts are disposed in a contact holder being offset with respect to each other in a second direction. A mounting for the contact holder holds the contact holder so that it can move in the first direction-and in a third direction with respect to the mounting. The first direction, second direction and third direction are orthogonal to each other in pairs. A spring acts upon the contact holder with a force opposite to the first direction. An end face oriented opposite to the first direction is provided with a centerer which cooperates with a centering support on the battery pack in order to prevent a relative movement between the end face and the battery pack in the third direction.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a hand-held machine tool, e.g., a drill hammer, a saw, [or] a nail gun. Electrical consumers of the hand-held machine tool, in particular of an electric motor, are supplied by a battery pack. The battery pack is removable from the hand-held machine tool. The battery pack may then be inserted into a charger for charging or be replaced with an identical charged battery pack. 
       BACKGROUND 
       [0002]    A drill hammer generates strong vibrations which cause stress on a mounting and the electrical contacts of the battery pack. The electrical contacts are thus not only subject to mechanical wear, but also due to arcs created during opening and closing of the contacts. 
       SUMMARY OF THE INVENTION 
       [0003]    The hand-held machine tool according to the present invention has an integrated tool or a tool holder for accommodating a tool. An electric motor drives the tool or the tool holder. A battery pack is insertable into a guide along a first direction for supplying the electric motor with power. Electrical contacts are situated offset from each other along a second direction, transversely to the first direction, in a contact holder. The electrical contacts are preferably situated with play in the contact holder. A suspension for the contact holder movably holds the contact holder with respect to the suspension along the first direction and along a third direction. The first direction, the second direction, and the third direction are orthogonal with respect to each other in pairs. A spring applies a force to the contact holder against the first direction. A front face pointing against the first direction is provided with a centering, which cooperates with a centering support on the battery pack to suppress a relative movement between the front face and the battery pack along the third direction. 
         [0004]    The contact holder is movably attached to the hand-held machine tool in at least two directions. The suspension of the contact holder is constructed in such a way that the movement along the first direction and the third direction is preferably limited to a first travel distance and a second travel distance. 
         [0005]    The battery pack inserted into the hand-held machine tool electrically couples to the electrical contacts and mechanically couples to the contact holder. Initially, the battery pack shifts the contact holder against the spring, whereby a force fit is achieved. Moreover, a form lock of the centering is obtained at the contact holder with the centering support on the battery pack. The centering locally holds the front face in a fixed position with respect to the battery pack along the third direction. 
         [0006]    One embodiment provides for the centering to include a mandrel which projects in the first direction and has a surface which is inclined with respect to the third direction and/or a notch which is recessed with respect to the first direction and has a surface which is inclined with respect to the third direction. Compared to an obtuse or non-inclined surface, the inclined surface causes secure centering. The inclination of the surfaces with respect to the third direction is preferably greater than 30 degrees. For example, the mandrel has a tip in the shape of an isosceles triangle in the cross section in parallel to the first and third directions. 
         [0007]    One embodiment provides for the contact holder, together with the mandrel and/or the notch, to be pressed against the battery pack, and for the front face otherwise to be spaced apart from the battery pack. The spacing of the non-inclined surfaces of the front face prevents an impairment of the centering by these non-inclined surfaces. 
         [0008]    One embodiment provides for the contacts to be situated movably with respect to each other in the contact holder. The contacts are preferably situated with play in the contact holder. Locally occurring vibrations on a contact may thus be kept away from other contacts. 
         [0009]    The contacts may be formed as jacks for accommodating blade-shaped contacts of the battery pack. The jacks are slotted along the third direction, for example. The counter contacts preferably have a blade shape and are oriented in parallel to the third direction. 
         [0010]    One embodiment provides for at least one of the contacts to be electrically contacted via a braided strand. 
         [0011]    One embodiment provides for the contact holder to be exposed in the first direction. The contact holder is connected to the hand-held machine tool only in a force-fit manner in the first direction via the spring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The following description explains the present invention based on exemplary specific embodiments and figures. 
           [0013]      FIG. 1  shows a drill hammer; 
           [0014]      FIG. 2  shows a cross section through the drill hammer in plane II-II; 
           [0015]      FIG. 3  shows a cross section through the drill hammer in plane III-III; 
           [0016]      FIG. 4  shows a partial section through a suspension; 
           [0017]      FIG. 5  shows a top view onto a contact holder; 
           [0018]      FIG. 6  shows a cross section through the drill hammer in plane V-V; 
           [0019]      FIG. 7  shows a drill hammer; 
           [0020]      FIG. 8  shows a cross section through the drill hammer in plane VII-VII. 
       
    
    
       [0021]    Identical or functionally equivalent elements are identified by identical reference numerals in the figures, unless indicated otherwise. 
       DETAILED DESCRIPTION 
       [0022]      FIG. 1  schematically shows a drill hammer  1  as one example of a hand-held machine tool. Drill hammer  1  has a tool holder  2 , into which a shaft end  3  of a tool, e.g., one of drill bit  4 , may be inserted. An electric motor  5 , which drives a hammer mechanism  6  and an output shaft  7 , forms a primary drive of drill hammer  1 . A user may guide drill hammer  1  with the aid of a handle  8  and put drill hammer  1  into operation with the aid of a system switch  9 . During operation, drill hammer  1  continuously rotates drill bit  4  about a working axis  10  and may strike drill bit  4  in percussion direction  11  along working axis  10  into a substrate. 
         [0023]    Hammer mechanism  6  is a pneumatic hammer mechanism  6 , for example. An exciter  12  and a striker  13  are movably guided in hammer mechanism  6  along working axis  10 . Exciter  12  is coupled to motor  5  with the aid of an eccentric  14  or a wobble finger and is forced to carry out a periodic, linear movement. A pneumatic spring, formed by a pneumatic chamber  15  between exciter  12  and striker  13 , couples a movement of striker  13  to the movement of exciter  12 . Striker  13  may strike directly onto a rear end of drill bit  4  or transfer its pulse to drill bit  4  indirectly via an essentially resting intermediate striker  16 . Hammer mechanism  6 , and preferably the further drive components, are situated inside a machine housing  17 . 
         [0024]    Electric motor  5  is supplied with power by a battery pack  18 . Battery pack  18  has a battery housing  19  which is separated with respect to drill hammer  1  and in which multiple battery cells  20  are situated. Battery pack  18  may be inserted into and removed from a mounting  21  of drill hammer  1 . Mounting  21  is preferably formed on an essentially exterior surface  22  of machine housing  17  or of handle  8 . Mounting  21  has a guide  23  made of two parallel grooves  24 , for example, which are oriented along an insertion direction  25  and situated offset from each other in a second (horizontal) direction  26  ( FIG. 2 ). Battery housing  19  of battery pack  18  is provided with two parallel rails  27  having an L-shaped profile. Battery housing  19  may be inserted with its rails  27  into grooves  24  of guide  23  and inserted along insertion direction  25  predefined by guide  23 . Guide  23  and battery housing  19  alternatingly engage behind each other along a third (vertical) direction  28 . Battery pack  18  is mounted by guide  23  in orthogonal directions  26 ,  28  with respect to insertion direction  25 , preferably with little play or without play. 
         [0025]    Mounting  21  is provided with depressions oriented perpendicularly to guide  23 , into which locking pins  29  of battery pack  18  may engage ( FIG. 3 ). Locking pins  29  are preferably pretensioned by springs and snap into place as soon as battery pack  18  has been inserted into mounting  21  up to a stop. Locking pins  29  lock battery pack  18  against a movement along insertion direction  25 . The user may disengage locking pins  29  from mounting  21  by actuating a push button  30  to be able to pull battery pack  18  out of mounting  21  against insertion direction  25 . The design of guide  23  is only exemplary; in particular, mounting  21  may be provided with locking pins  29  and/or mounting  21  may be provided with rails  27  having an L-shaped profile. 
         [0026]    Mounting  21  is provided with electrical contacts  31 , which contact electrical counter contacts  32  of battery pack  18 . The contact is established when battery pack  18  is locked in guide  23 . Contacts  31  are preferably situated next to each other along second direction  26 , and otherwise are preferably situated at the same height, in particular along third direction  28 . 
         [0027]    Advantageously two current-conducting contacts  33  and two or more signal-conducting contacts  34  are provided. Current-conducting contacts  33  are designed for more than 10 amperes to supply drill hammer  1  with power. Contacts  31  are made up entirely of metal; in view of the mechanical loads of a drill hammer  1 , they are made up of an iron-containing alloy, preferably having a high copper content. Signal-conducting contacts  34  are designed for a lower load since currents of less than 10 mA flow over these. 
         [0028]    Electrical contacts  31  of drill hammer  1  are slotted jacks. Opposing jaws  35  of contact  31  may have a resilient design. During insertion of electrical counter contacts  32  of battery pack  18  between jaws  35 , these resilient jaws  35  are preferably pushed apart and thus clamped against counter contacts  32 . Electrical contacts  32  of battery pack  18  may be designed as blades. The slots or blades preferably extend in parallel to third, vertical direction  28 . 
         [0029]    Electrical contacts  31  are inserted into an electrically insulating contact holder  36  ( FIG. 5 ). Contacts  31  are situated next to each other and are spaced apart from each other in second direction  26 . Contact holder  36  preferably has a separate accommodating space  37  for each of electrical contacts  31 , in particular of current-conducting contacts  33 . Electrical contact  31  may move in accommodating space  37  along insertion direction  25 ; the play is in the range of 0.1 mm to 0.3 mm, for example. Electrical contacts  31  may include spring-loaded wings, which project in second direction  26  and with which electrical contacts  31  are supported against the side walls of accommodating spaces  37 . Due to their movable arrangement, contacts  31  are movable with respect to each other within contact holder  36 . Accommodating spaces  37  are open on a front face  38  pointing against insertion direction  25 . Counter contacts  32  of battery pack  18  may be inserted through opening  39  into accommodating spaces  37  and to electrical contacts  31  situated therein. 
         [0030]    A strand  40  is crimped or clamped to each of contacts  31  or is clamped to electrical contact  32  ( FIG. 5 ). Strands  40  are guided in contact holder  36  in a channel  41  in each case. In the shown specific embodiment, a terminal strip  42  is provided in contact holder  36 . One end of strands  40  is attached to one of contacts  31  and the other end is attached in terminal strip  42 . Terminal strip  42  mechanically decouples strands  40  from the wiring inside drill hammer  1 . In this way, in particular a transfer of torsional forces of the lines which are partially twisted during installation to strands  40  is suppressed. The torsional forces could otherwise result in contacts  32  becoming clamped against side walls of accommodating spaces  37 . Strands  40  are composed of braided wires. Strands  40  braided into a braid preferably have no insulating plastic jacket for at least 2 cm inside contact holder  36 . The braid may be deformed by the introduced torsional forces and thus decouples the same from contacts  31 . Strands insulated with a heat-shrinkable tubing or strands with twisted wires prove to be unfavorable for this purpose, as do even strands having very fine wires. 
         [0031]    Terminal strip  42  is situated on the end of contact holder  36  facing away from front face  38 , for example. Terminal strip  42  may be provided with electromechanical coupling pieces  43 . Coupling piece  43  connects strand  40  to another cable  44 , which is guided into machine housing  17 . Coupling piece  43  is designed, for example, as a luster terminal having two screws  45  for fixing strand  40  and cable  44 . Coupling pieces  43  are immovably inserted into contact holder  36 . As an alternative or in addition to coupling pieces  43 , terminal strip  42  may include a constriction  46  in channel  41  into which strand  40  is squeezed. 
         [0032]    Contact holder  36  is movably suspended with respect to machine housing  17 . A suspension  47  of contact holder  36  allows a limited movement of contact holder  36  along insertion direction  25 . For this purpose, suspension  47  may have longitudinal grooves  48  in machine housing  17 , for example, in which guide rails  49  engage on contact holder  36  ( FIG. 4 ). Stops  50 ,  53  on both sides of contact holder  36  limit the movement to a travel distance  51 ,  54  of 2 mm to 5 mm in total, for example. One or multiple springs  52 , e.g., helical springs, act on contact holder  36  against insertion direction  25 . While battery pack  18  is not inserted, springs  52  press contact holder  36  against front stop  50  in insertion direction  25 . Springs  52  are placed under pretension. During insertion of battery pack  18 , contact holder  36  is entrained by battery pack  18  against the force of springs  52  in insertion direction  25 . Travel distance  51 ,  54  is dimensioned in such a way that contact holder  36  is still spaced apart from rear stop  53  in insertion direction  25  by a portion  54  of travel distance  51 ,  54  when lock  29  locks battery pack  18 . 
         [0033]    Contact holder  36  is also able to move slightly in suspension  47  along second direction  26 , contrary to battery pack  18  in mounting  21 . The clearance for the movement is preferably at least 1 mm in second direction  26 . The distance of opposing longitudinal grooves  48  is greater by the clearance than the width of contact holder  36  in the area of guide rails  49 . 
         [0034]    Moreover, contact holder  36  is able to move freely along third direction  28  between vertical stops. Free travel distance  55  between the stops is in the range of 0.5 mm to 2 mm The vertical stops are formed by groove walls of longitudinal grooves  48 , for example, whose distance is greater by travel distance  55  than the dimension of guide rails  49  along vertical direction  28 . 
         [0035]    As an alternative or in addition, movable contact holder  36  may be suspended in a bracket  56  which is attached to handle  8  or machine housing  17 . Bracket  56  is situated behind contact holder  36  in insertion direction  25 . Contact holder  36  has one or multiple pins  57  projecting in insertion direction  25 , which are inserted into jacks  58  of bracket  56 . Jacks  58  are wider and higher than pins  57  to ensure the movability of contact holder  36  in second direction  26  and third direction  28 . Springs  52  may be mounted in bracket  56  and be supported on bracket  56 . Bracket  56  forms rear stop  53 . Strands  40  or cables  44  may be guided in bracket  56  essentially in parallel to insertion direction  25 . 
         [0036]    Contact holder  36  is provided with a vertical centering  59  on front face  38 . The vertically, i.e., along third direction  28 , acting centering  59  engages in a complementary centering support  60  on battery pack  18 . Springs  52  press centering  59  into centering support  60  and fix the relative vertical position of front face  38  with respect to battery pack  18  in a force-fit and form-locked manner. Front face  38  and mounting  21  continue to remain movable with respect to machine housing  17  and drill hammer  1 . Front face  38  is able to move with respect to machine housing  17  by free travel distance  55  along vertical third direction  28 . Centering  59  is dimensioned along insertion direction  25  in such a way that only centering  59  rests against battery pack  18 . The remaining areas of contact holder  36  are spaced apart along insertion direction  25 . Contacts  31 ,  32  contact each other or are inserted into each other. 
         [0037]    Centering  59  shown by way of example is implemented with the aid of mandrels  59  projecting from front face  38 . Mandrels  59  are wedge-shaped, pyramid-shaped or cone-shaped. A top surface  61  of mandrel  59  pointing toward machine housing  17  is inclined with respect to third direction  28 . Top surface  61  moves away from machine housing  17  against insertion direction  25  along third direction  28 . As an alternative or in addition to top surface  61 , a bottom surface  62 , which faces away from machine housing  17 , may be inclined with respect to third direction  28 . Bottom surface  62  ascends toward machine housing  17  against insertion direction  25  along third direction  28 . Mandrels  59  are preferably situated along second direction  26  between contacts  32 . In the preferred example, mandrels  59  directly adjoin accommodating spaces  37  of current-conducting contacts  33 . 
         [0038]    Battery pack  18  has a contact carrier  63 , which is preferably immovably joined to battery housing  19 . Contact carrier  63  is made of an electrically insulating material, for example a plastic material. Counter contacts  32  are immovably embedded in the plastic material. Counter contacts  32  are preferably designed as blades, which are situated in planes parallel to insertion direction  25  and third direction  28 . Centering support  60  is situated between counter contacts  32 , for example. Front face  64  of centering support  60  pointing in insertion direction  25  is provided with a notch, whose shape is designed complementary to mandrel  59 . The notch preferably has a prismatic design, i.e., the cross section of the notch is constant along second direction  26 . Centering  59  thus acts only in third direction  28  and does not exert any influence on a movement along second direction  26 . 
         [0039]    The arrangement of centering  59  and of centering support  60  directly next to current-conducting contacts  33  or counter contacts  32  proves to be advantageous even with stiff materials for contact holder  36  and contact carrier  63  to sufficiently suppress a relative movement along third direction  28  between current-conducting contacts  33  and counter contacts  32 . 
         [0040]    Centering  59  on front face  38  of contact holder  36  may be designed as a notch, and the centering support may be designed as a mandrel. The centering may moreover include both notches and mandrels, the centering supports having a corresponding complementary design. 
         [0041]    Strand  40  may be inserted in channel  41  in a wave shape ( FIG. 7 ,  FIG. 8 ). The dimension of channel  41  is at least 50% greater in second direction  26  than the cross section of strand  40 . Strand  40  extends between terminal strip  42  and contacts  31 . However, the length of strand  40  is at least 10% greater than the distance from terminal strip  42  and contacts  31 . Strands  40  change their direction of progression multiple times along insertion direction  25  based on second direction  26  or third direction  28 . In this way, effective damping of movements in the submillimeter range of the contacts could be achieved. The wires of strands  40  may be braided into a braid. 
         [0042]    In addition to a chipping hammer, a nail gun for nails and bolts, and a saber saw, drill hammer  1  is one example of a battery-powered electric hand-held machine tool which is exposed to strong vibrations during operation and may be provided with movable contact holder  36 . The nail gun generates strikes with the aid of the striker impacting the nails as a tool, which may result in a relative movement of the battery pack and the machine housing. In saws, in particular saber saws, the vibrations are generated by the saw blade and transferred to the machine tool.