Abstract:
A portable power drill or hammer drill having a housing ( 12 ) which consists in particular of half shells ( 13, 14 ) and accommodates a manual gearbox ( 26 ), wherein a shift element ( 59 ) that can be rotated by hand converts its rotary movement into a shift movement, can be produced cost-effectively and can be easily operated, without lubricant escaping from the housing ( 12 ), by the shift element ( 59 ) consisting of a shell-like handle part ( 100 ) which can be joined together with a further, shell-like shift part ( 102 ) in a sealing manner from outside and inside relative to a housing shell ( 13 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2005 041 448.6 filed on Aug. 31, 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 present invention relates to a portable power drill or a drill hammer. 
   Many kinds of systems for shifting the change-speed gears of portable power drills and drill hammers are known, such as rotatable selector elements and levers with which various operating states can be selected; in these systems, the selector elements must pass through the housing wall. 
   To that end, it is usual to use selector elements designed as a one-piece component with complex locking contours, mounted on the gearbox. A disadvantage is that producing these complex components requires complicated, expensive tools, and the sealing between the housing wall and the selector element is problematic. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the invention to provide a portable power drill with a gear box which eliminates the disadvantages of the prior art. 
   In keeping with these objects and with others, one feature of the present invention resides, briefly stated, in a portable power drill or drill hammer, comprising a housing composed of half-shells; a shiftable change-speed gear received in said housing and having a manually hand-rotatable selector element which converts a rotary motion into a shifting motion, said selector element having a circular shell-shaped handle part outer handle part which is joinable with a further circular shell-shaped inner selector part so as to be sealed from outside and inside relative to one of said half shells, said inner selector part having a spring which is configured as leaf spring arranged in a form-locking fashion in said inner selector part, so that it radially overlaps said selector part at both sides and is supported with both overlapping ends inside on said half-shell. 
   When the portable power drill is designed in accordance with the present invention it has the advantage that an economical selector element is created which can be mounted simply and securely, functions reliably, has a long life, and is sealed. 
   The invention is described below in further details in terms of an exemplary embodiment, in conjunction with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1 , an exploded drawing of the drill hammer of the invention; 
       FIG. 2 , an exploded drawing of the selector element; 
       FIG. 3 , an external view of a drill hammer housing provided with the selector element; 
       FIG. 4 , an internal view of a drill hammer housing provided with the installed selector element; 
       FIG. 5 , an inside view of an outer part of the selector element, the outer part being positioned from outside on the drill hammer housing; 
       FIG. 6 , an inside view of the outer and inner parts of the selector element that are seated on the drill hammer housing without a leaf spring; 
       FIG. 7 , a three-dimensional back view of the assembled selector element; 
       FIG. 8 , a three-dimensional top view on the inner part of the selector element; and 
       FIG. 9 , a three-dimensional view of the leaf spring of the selector element. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The exploded view in  FIG. 1  shows a drill hammer  10  with a housing  12 ; the housing comprising two half-shells  13 ,  14  of plastic, with a vertical parting line  15 . The housing  12  receives a motor  16  with an ON/OFF switch  18  and a suitable power cord  20  for connection to an external power source, as well as a gear  26  and a percussion mechanism  36 . The motor  16  includes a motor shaft  22 , whose free end has a motor pinion  24  that is supported in an intermediate flange  25  that can be positionally secured between the half-shells  13 ,  14 . The motor pinion  24  is in engagement with a driving gear wheel  30  of an intermediate shaft  28  of the gear  26 , the intermediate shaft being supported by one end in the intermediate flange  25  via a needle bearing, not shown. Adjoining this, a swash gear wheel  38  is rotatably supported on the intermediate shaft  28 , adjacent to a driving gear wheel  30  seated firmly on it and in particular press-fitted onto it. The swash gear wheel  38  has a swash plate  40  with a wobbling prong  42 , as part of the percussion mechanism  36 . Axially adjacent to the swash gear wheel  38 , a slaving gear wheel  32  is seated rotatably but in a manner fixed against relative rotation on the intermediate shaft  28 , in particular being press-fitted on, and the slaving gear wheel  32  is followed axially adjacent it by a driven gear wheel  35 , which is axially secured by a roller bearing  45 , seated firmly on the other end of the intermediate shaft  28 ; the slaving gear wheel  32  is embraced by a shift sleeve  34  in such a manner that it is slaved rotationally and is axially displaceable. The driven gear wheel  35  of the intermediate shaft  28  meshes with the driving gear wheel  48  of the driven shaft  46 ; with the gear  26 , by displacement of the shift sleeve  34  with switching means  52 , the rotary motion of the motor  16  can be selectively adjusted by hand by means of selector element  59  to a purely rotary motion, or in other words drilling, or a purely reciprocating motion, or in other words chiseling, or a rotary and reciprocating motion, or in other words drill hammering, of the driven shaft  46 . 
   Adjoining the wobbling prong  42 , the percussion mechanism  35  continues with a percussion element  44 , which via the swash plate  40  transmits percussive energy, converted from a rotary motion to a translational motion, to a chisel or drill restrained axially displaceably on a drill chuck  50  seated on the driven shaft  46  or on the end thereof. 
   The shift sleeve  34  has an annular-groovelike slot  33  on its circumference, for engagement by a gearshift fork  52 , which is part of a shift plate  54  designed in particular as a one-piece bent sheet-metal part. The shift plate  54  is a sheet-metal part bent into a U, the first leg of which U, with a semicircular recess, embraces the shift sleeve  34  or the slot  33 , and the other leg of which U serves as a locking fork  56  and is provided with a tooth hub profile  58 , located in a semicircular recess, for engagement with the serrated shaft profile of the driven gear wheel  35 . In the aforementioned engagement, the driven gear wheel  35  is simultaneously released from the slaved rotation by the shift sleeve  34  and is locked in a manner secured against relative rotation. Thus with the selector element  59 , a selectable rotary position of the driven shaft  46  for chiseling can be fixed. The shift plate  54  is longitudinally displaceable axially parallel to the intermediate shaft  28  via a guide rod  51 , which penetrates a guide bore  53  that passes transversely through the gearshift fork  52  and the locking fork  56 . For displacement of the shift plate  54 , the selector element  59 , on the order of a rotary knob, is used; its rotation can be transmitted, via its eccentric cam  59 , as a sliding motion to a protrusion  55  of the shift plate  54 . 
   The rotary motion of the electric motor  16  is transmitted via the driving gear wheel  30  to the intermediate shaft  28  and the slaving gear wheel  32 . The slaving gear wheel, of sintered material, is in the form of a serrated shaft, whose profile extends over its entire external length. The swash gear wheel  38  can be coupled in a manner fixed against relative rotation to the slaving gear wheel  32  via the suitably positioned shift sleeve  34 , and then the rotary motion of the intermediate shaft  28  is converted, via the swash plate  40  and the wobbling prong  42 , into a translational motion of the percussion element  44 . 
   The driven gear wheel  35 , seated rotatably on the intermediate shaft  28 , can be coupled in a manner fixed against relative rotation to the slaving gear wheel  32  via the shift sleeve  28 , and part of the driven gear wheel  35  has a serrated shaft profile  31  and  66 , which corresponds to the tooth hub profile  29  of the shift sleeve  28 , and a further part of the driven gear wheel  35  has a spur gear profile  68  for transmitting rotation to the driving gear wheel  48  of the driven shaft  46 . As a result, the rotary motion of the intermediate shaft  28  can be transmitted to the driven shaft  46  and to the drill chuck  50  secured therein, or to a tool insert in the form of a drill or chisel seated therein. The coupling or shifting between the slaving gear wheel  32  and the axially adjacent swash gear wheel  38  or driven gear wheel  35  is effected via the shift sleeve  34 , whose positioning is established solely by way of the form lock between the slot  33  and the gearshift fork  52  engaging it, without any friction losses occurring in the operation of the drill hammer  10 . Thus the shift sleeve  34 , in all three switching positions, remains unsubjected to axial force, resulting in less wear and a longer service life. 
   If upon axial displacement of the shift sleeve  34  the corresponding serrated shaft/tooth hub profiles of the swash gear wheel  38  or driven gear wheel  35  meet one another on the face end with that of the shift sleeve  34 , shifting synchronizing means make the shifting easier. To that end, on their side toward the slaving gear wheel  32 , each of the serrated shaft profiles of the swash gear wheel  38  or driven gear wheel  35  has a parallel tooth width reduction  62 ,  64  of approximately ⅔ of the tooth width over a tooth length of approximately 1 to 2 mm. This leads to a partial widening of the tooth gaps of the serrated shaft profile and facilitates the entry there of the tooth hub teeth of the shift sleeve  34 . 
   In a transitional position in shifting from the percussion drilling mode to the chiseling mode, the drill chuck  50  or the chisel can be rotated by hand into a desired working position. After the shifting to the chiseling mode shifting position, the selected rotary position of the chisel is maintained by way of the locking with the locking fork  56 . 
   The shift travel amounts to approximately 5 mm of displacement distance of the shift sleeve  34 , or rotational distance of the selector element  59  to the right or left. 
   The selector element  59  comprises a shell-like outer, hand-actuatable handle part  100  and an inner selector part  102 , centrally fitting into the outer handle part  100 , with a cam  74 , with which the shifting operation for selecting a gear or changing gears is accomplished. Both parts can be screwed together on a housing shell  13  in a manner that is sealed off from the housing shell; a sealing ring  104  is held in prestressed fashion between the edge of the inner selector part  102  and the inner wall of the housing shell  13 . 
   The inner selector part  102 , on its inside, has a rectilinear, groovelike recess  120  for form-locking reception of an elongated, rectilinear leaf spring  103  with a central through hole  107  for a mounting screw  106 . The outer ends of the leaf spring  103  have camlike indentations  105 , which fit into corresponding associated indentations  113  on the inside of the housing shell  13  and define overloadable adjustment positions of the selector element  59 . 
   The outer handle part  100  can be screwed to the inner selector part  102  by passing a screw through its central through hole  109  to engage a threaded hole  108  of the handle part  100 . The inner selector part  102  is aligned with a centering ring  112  of the handle part  100 . 
   The handle part  100  has a twist knob  110  protruding in beamlike fashion, which rests graspably in the user&#39;s hand and allows the handle part or the selector element  59  to be easily rotated. The housing shell  13 , outside the circumference of the handle part  100 , has an outward-protruding stop  114  as well as graphic symbols  116 ,  117 ,  118  that can be felt by the hand. The stop  114  corresponds to the beamlike twist knob  110 , upon whose rotation, in the chiseling position, the user&#39;s hand meets the stop  114  and can tell that the chiseling position has been reached. 
   Thus an indexing and positional fixation of the selector element  50  and hence of the gearshifting in the selected position is assured.