Abstract:
A clutch device for an electric machine tool that is drivable in a fashion selected from the group consisting of a rotary fashion, a percussion fashion, and both with an impact mechanism deliberately disengageable from or engageable with a spindle that drives a plug-in tool, has an intermediate shaft arranged between the spindle and an armature shaft of a drive motor and configured for transmitting drive energy, the intermediate shaft being axially movable so that the electric machine tool is switchable between operating modes through an axial movement of the intermediate shaft.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
   The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2005 036 731.3 filed on Aug. 4, 2005. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
   BACKGROUND OF THE INVENTION 
   The invention is based on a clutch device for an electric machine tool as and an electric machine tool. 
   Rotary hammers and chisel hammers can be used in a variety of operating modes. These types of operation are broken down into rotary drilling, e.g. when drilling into wood and steel, screw driving, stirring etc.; percussion drilling, e.g. when drilling into concrete, stone, etc.; and chiseling, e.g. when removing wall plaster or tiles and when producing openings in walls, etc. 
   The operating modes are usually produced by means of the mechanical transmission. Rotary drilling is characterized by the impact mechanism being deactivated while the spindle rotates. In percussion drilling, the impact mechanism is added to this spindle rotation. In chiseling mode, the spindle is disengaged from the rotary drive while the spindle is simultaneously locked in position (“spindle lock”). 
   Depending on the structural design of the transmission, an intermediate shaft is supported in stationary fashion by the housing or a flange and the switching occurs by means of components that are slid on the intermediate shaft. The intermediate shaft can also be comprised of several parts and the individual parts can be supported one inside the other so that the individual operating modes are produced by sliding the parts in the axial direction. This does enable a compact, short design, but requires all the forces of the impact mechanism and the torque to be introduced via the intermediate shaft and the bearing. 
   If the drive end bearing is supported directly in the housing, then it is possible to achieve a rugged, solid construction. This permits the intermediate shaft to then likewise be stationary and the switching to be achieved as described above. If the intermediate shaft is supported so that it can move in the axial direction, then this can be used to execute the switching, but results in a critical structural length and complicates placement of a customarily provided spur gear of the first transmission stage. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a clutch device for an electric machine tool, as well as an electric machine tool, which eliminates the disadvantages of the prior art. 
   In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a clutch device for an electric machine tool that is drivable in a fashion selected from the group consisting of a rotary fashion, a percussion fashion, and both with an impact mechanism deliberately disengageable from or engageable with a spindle that drives a plug-in tool, the clutch device comprising an intermediate shaft arrangeable between the spindle and an armature shaft of a drive motor and configured for transmitting drive energy, said intermediate shaft being axially movable so that the electric machine tool is switchable between operating modes through an axial movement of said intermediate shaft. 
   Another feature of the present invention of the present invention resides, briefly stated, in an electric machine tool, drivable in a fashion selected from the group consisting of a rotary fashion, a percussion fashion, and both, comprising a plug-in tool; a spindle driving said plug-in tool; an impact mechanism deliberately engageable from or engageable with said spindle; and a clutch device, said clutch device including an intermediate shaft arrangeable between the spindle and an armature shaft of a drive motor and configured for transmitting drive energy, said intermediate shaft being axially movable so that the electric machine tool is switchable between operating modes through an axial movement of said intermediate shaft. 
   With the clutch device according to the present invention, the intermediate shaft is moved in the axial direction in order to switch between operating modes of the electric machine tool. The axial movement of the intermediate shaft can be redirected into a radial function for engaging or disengaging one or more rotary drive connections in which the drive elements of a rotary drive connection can be controlled to produce a transmission of drive energy between the drive unit and the impact mechanism and/or intermediate shaft. 
   It is possible to combine the principal advantages of a stationary support of a drive end bearing and an axial movement. This makes it possible to achieve a compact, short design and precisely this kind of switching between the various operating modes. At the same time, this makes it possible to avoid the transmission of forces from the impact mechanism to the intermediate shaft. 
   In a preferred embodiment, an operational connection between the armature shaft and a drive end bearing of the impact mechanism can be engaged or disengaged as a function of an axial position of the intermediate shaft. The axial position can serve to determine the operating mode of the electric machine tool, e.g. for drilling, chiseling, or percussion drilling. 
   In another favorable embodiment, the intermediate shaft is provided with a constriction; in a corresponding axial position of the shaft, one or more driving elements of a rotary drive connection between the drive end bearing and a toothed sleeve, which is drive-connected to the armature shaft, are able to move into this constriction, thus disengaging the rotary drive connection and therefore the impact mechanism. Because the driving element or elements can move into an empty space provided by the constriction, the intermediate shaft controls the radial position of the driving element or elements. In this position, the drilling mode is engaged and the impact mechanism is disengaged. The driving element or elements can, for example, be embodied in the form of balls. 
   In another favorable embodiment, an insertion gearing is provided for producing a drive connection between the intermediate shaft and the toothed sleeve. This makes it possible to engage or disengage a rotary drive connection by sliding the intermediate shaft in the axial direction. 
   In another favorable embodiment, between the constriction and a toothed region of the intermediate shaft associated with the insertion gearing, the intermediate shaft is provided with a region that pins the driving element or elements in position in the rotary drive connection. This makes it possible to assure a transmission of drive energy between the armature shaft and the impact mechanism provided that the intermediate shaft is in such an axial position that the region holds the driving element or elements in its/their driving position. If, for example, the insertion gearing is disengaged, but the driving elements are pinned in position, then this produces the chiseling mode. The spindle is then locked in a suitable fashion. 
   In another favorable embodiment, the intermediate shaft has a toothed element that is provided for drive connection with the spindle. The toothed element is of a suitable axial length to preserve the operational connection when the intermediate shaft is slid in the axial direction. 
   In another favorable embodiment, the intermediate shaft can be immobilized by a locking mechanism in order to prevent spindle motion. This position can produce a chiseling mode in which it is undesirable for the spindle to rotate. In this case, it is preferable for the insertion gearing between the intermediate shaft and the toothed sleeve to be disengaged and for the intermediate shaft to pin the driving element or elements in the driving position. 
   In another favorable embodiment, the intermediate shaft can be slid in the axial direction by means of a control element that can be externally actuated. 
   In another favorable embodiment, the toothed sleeve is supported in an intermediate flange and/or in the drive end bearing. This makes it possible to achieve a reliable, stable support. It is therefore possible to prevent an introduction of force from the impact mechanism. 
   The present invention also relates to an electric machine tool in which it is possible to switch between operating modes of the electric machine tool through an axial movement of an intermediate shaft that is situated between a spindle and an armature shaft of a drive motor and is provided to transmit drive energy to the spindle. 
   The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a detail of a transmission region of a preferred rotary hammer in the percussion drilling position; 
       FIG. 2  shows a detail of a transmission region of a preferred rotary hammer according to  FIG. 1 , in the chiseling position; 
       FIG. 3  shows a detail of a transmission region of the preferred rotary hammer according to  FIG. 1 , in a drilling position; and 
       FIGS. 4   a, b  show a section through a drive end bearing ( FIG. 4   a ) and a top view of an end surface of the drive end bearing provided with a drive profile ( FIG. 4   b ). 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   By way of example,  FIG. 1  shows a detail of a rotary hammer transmission of an electric machine tool preferably embodied in the form of a rotary hammer, in a percussion drilling mode. 
   The preferred clutch device for the electric machine tool equipped with a plug-in tool, not shown, which can be plugged into a spindle  23  and can be driven in a rotary and/or percussive fashion, includes an intermediate shaft  10  and a toothed sleeve  13 , having drive elements  18  situated between the toothed sleeve  13  and a drive end bearing  11 . The intermediate shaft  10  is situated between the spindle  23  and an armature shaft  22  of a drive motor, not shown. Like the toothed sleeve  13 , the armature shaft  22  is supported in an intermediate flange  27 . 
   An impact mechanism  32  can be deliberately engaged with or disengaged from the spindle  23 , which drives the plug-in tool, depending on the axial position of the intermediate shaft  10 . The electric machine tool is switched between operating modes through an axial movement of the intermediate shaft  10 . 
   At its end oriented toward the intermediate flange  27 , the intermediate shaft  10  has an external gearing  15  that forms an insertion gearing  31  together with an internal gearing  14  of the toothed sleeve  13 . The insertion gearing  31  constitutes a rotary drive connection between the toothed sleeve  13  and the intermediate shaft  10 . An adjacent region  33  of the intermediate shaft  10  has a sufficient diameter in order, in the corresponding axial positions, to pin the drive elements  18 , which are secured in the toothed sleeve  13 , in their driving position between the drive end bearing  11  and the toothed sleeve  13 . 
   Adjacent to the region  33 , the intermediate shaft  10  has a constriction  29  and then, adjoining this constriction  29 , widens out again into a bearing region of a bearing  16  in the drive end bearing  11  of the impact mechanism  32 . Axially outside the drive end bearing  11 , the intermediate shaft  10  has a sliding mechanism  17  that can be actuated externally in order to slide the intermediate shaft  10  in the axial direction. Adjacent to this, a toothed element  24  is rotationally fixed to the intermediate shaft  10  and engages with a gearing  25  of the spindle  23 . At its end oriented away from the toothed sleeve  13 , the intermediate shaft  10  is supported in a bearing  20 . 
   Disengaged from the toothed element  24 , a locking mechanism  21  is provided, which, in the corresponding axial position, can lock the intermediate shaft  10  so that it cannot rotate, thus preventing the spindle  23  from rotating. 
   The armature shaft  22  transmits its rotary motion to an external gearing of the toothed sleeve  13  by means of a gearing  28 . The rotary drive connection  30  between the drive end bearing  11  and the toothed sleeve  13  is provided by means of the driving elements  18 . These drive elements are radially encapsulated in the toothed sleeve  13  and are controlled in their radial position by the intermediate shaft  10 . A drive profile  19  for the drive elements  18  is provided in the drive end bearing  11 . 
   The drive end bearing  11  of the impact mechanism  32  drives a wobble finger  26 , which converts a rotary motion of the drive end bearing  11  into an axial, percussive motion. The wobble finger  26  is supported in the usual way on an outside  12  of the drive end bearing  11 . 
   In the depicted axial position of the intermediate shaft  10 , the first rotary drive connection by means of the insertion gearing  31  between the toothed sleeve  13  and the intermediate shaft  10  and the second rotary drive connection  30  between the toothed sleeve  13  and the drive end bearing  11  are activated, thus permitting a rotating, percussive motion of the plug-in tool, e.g. during percussion drilling, in which the first rotary drive connection transmits the rotary motion of the armature shaft  22  to the intermediate shaft  10  and the second rotary drive connection  30  converts the rotary motion of the armature shaft  22  into a hammering motion of the impact mechanism  32 . 
     FIG. 2  shows the device from  FIG. 1  in the chiseling mode. The components have already been described in connection with  FIG. 1 . The intermediate shaft  10  is slid axially forward toward the plug-in tool. The rotary drive connection  30  between the drive end bearing  11  and the toothed sleeve  13  causes the rotary motion of the armature shaft (not shown) to be transmitted to the drive end bearing  11  and thus generates a percussive motion. In this instance, the region  33  of the intermediate shaft  10  pins the drive elements  18  in position radially, while the rotary drive connection by means of the insertion gearing  31  ( FIG. 1 ) is disengaged and a rotary motion of the armature shaft  22  cannot be transmitted to the intermediate shaft  10 . In addition, the toothed element  24  engages with the locking mechanism  21  so that the spindle  23  is prevented from rotating. This allows the rotary motion of the armature shaft to be converted into a purely percussive motion. 
     FIG. 3  shows the device from  FIG. 1  in the drilling mode. For drilling, the intermediate shaft  10  is slid rearward axially, away from the plug-in tool. The locking mechanism  21  ( FIG. 2 ) releases the toothed element  24  and the rotary drive connection is produced once more by the insertion gearing  31  between the toothed sleeve  13  and the intermediate shaft  10 . But the intermediate shaft  10  is now in an axial position in which the constriction  29  of the intermediate shaft  10  is aligned with the drive elements  18 , permitting them to move inward into an empty space constituted by the constriction  29 . This disengages the rotary drive connection  30  ( FIG. 2 ) between the toothed sleeve  13  and the drive end bearing  11 , disengaging the impact mechanism  32 . The rotary motion of the armature shaft  22  ( FIG. 1 ) is now converted into a purely rotary motion of the plug-in tool for rotary drilling. 
     FIG. 4   a  is a section through a drive end bearing  11 , showing a drive profile  19  for drive elements at one end of the drive end bearing  11 .  FIG. 4   b  shows a top view of the drive profile  19  of the drive end bearing  11 . 
   It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
   While the invention has been illustrated and described as embodied in a clutch device for an electric machine tool and an electric machine tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
   Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.