Abstract:
A hand power tool has a tool spindle rotatable by a drive train, a cam device located in the drive train and having two cam discs in engagement with one another for transmitting axial percussion motions to the tool spindle, an overloading coupling located in the drive train and having two coupling parts which are in engagement with one another and are overloadable counter to an axially exerted force, a blocking device which upon its activation blocks a relative rotation of the coupling parts of the overloading coupling to one another, and an operating mode setting device for setting “percussion drilling”, “drilling” and “screw driving” operating modes, and also a magnitude of an overlocking moment upon screwdriving and having one torque adjusting ring for setting the “drilling” operating mode and the “screwdriving” operating mode, with preselection of the magnitude of the overlocking moment, and another adjusting the “percussion drilling” operating mode on and off, and in “on” position overrides any operating mode set by the torque adjusting ring.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a hand power tool, in particular a drilling screwdriver. 
   In a known power percussion drill with a device for changing operating modes (German Patent Disclosure DE 100 06 641 A1), the adjusting or changing device has two adjusting rings or changing rings, which are located side by side on the power tool housing and are embodied such that one changing ring, in three successive setting positions, calls up the “percussion drilling” operating mode, the “drilling” operating mode, and the “screwdriving” operating mode, and the other changing ring, in the “percussion drilling” operating mode, over a plurality of setting positions predetermines the overlocking or overloading moment or torque of the overlocking or overloading coupling. 
   The changing device furthermore has a blocking device or disengagement device, which in the “percussion drilling” and “drilling” operating modes blocks the overlocking or overloading capability of the overlocking coupling. In the third setting position of the first changing ring, for calling up the “percussion drilling” operating mode, the disengagement device is deactivated, and the overlocking moment or torque of the overlocking coupling is determined by a coupling spring, whose spring prestressing is adjustable by means of the second changing ring. 
   SUMMARY OF THE INVENTION 
   In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a hand power tool, in particular a drilling screwdriver, which is a further improvement of the existing hand power tools. 
   In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a hand power tool, comprising a power tool housing; a tool spindle supported rotatably in said housing; a drive train via which said tool spindle is drivable to rotate; a cam device located in said drive train and having two cam discs in engagement with one another for transmitting axial percussion motions to said tool spindle; an overlocking or overloading coupling located in said drive train and having two coupling parts which are in engagement with one another and are overlockable or overloadable counter to an axially exerted force; a coupling spring exerting said axial force; a blocking device which upon its activation blocks a relative rotation of said coupling parts of said overlocking coupling to one another; and an operating mode setting device for setting “percussion drilling”, “drilling” and “screw driving” operating modes, and also a magnitude of an overlocking or overloading moment upon screwdriving, said operating mode setting device having two adjusting rings located on said power tool housing and rotatable manually to define setting positions and acting on said cam device, said overlocking coupling and said blocking device, wherein one of said adjusting rings is a torque adjusting ring and sets the “drilling” operating mode and the “screwdriving” operating mode, with preselection of the magnitude of the overlocking moment, while the other of said adjusting rings is embodied as a function adjusting ring and switches the “percussion drilling” operating mode on and off, and in its position that switches the “percussion drilling” operating mode on, it overrides any operating mode set by said torque adjusting ring. 
   When the hand power tool is designed in accordance with the present invention it has the advantage that the operating modes of “percussion drilling”, “drilling” and “screwdriving” with preselection of the overlocking moment or torque are divided up more logically between the adjusting rings and can be called up by means of shorter rotation paths of the adjusting rings. Hence regardless of the instantaneous setting of the torque adjusting ring, the percussion drilling function can be engaged by transferring the function adjusting ring to its one setting position. If the percussion drilling function is disengaged again by rotating the function adjusting ring in reverse, then the hand power tool resumes the operating mode specified at that instant by the torque adjusting ring. For setting the “percussion drilling” operating mode from the “drilling” or the “screwdriving” operating mode, thus the function adjusting ring merely needs to be rotated by a small rotary angle and does not—as in the known hand power tool—have to travel through the wide torque adjusting range of the “screwdriving” operating mode. The operating mode setting device is distinguished by good ergonomics and ease of use and has an attractive appearance. 
   In an advantageous embodiment of the invention, the torque adjusting ring, which has a plurality of setting positions, accesses the overlocking coupling and the blocking device in such a way that in the setting position of the torque adjusting ring that trips the drilling function, the blocking device is activated, while in the other setting positions of the torque adjusting ring it is deactivated, and the coupling spring of the overlocking coupling is prestressed variously strongly. The setting positions of the torque adjusting ring are preferably located such that with an increasingly long rotary path of the torque adjusting ring, the overlocking moment increases from one setting position to the next, and the setting position for calling up the drilling function adjoins the last one of these further setting positions. The function adjusting ring, which has only two setting positions, accesses the cam device and the blocking device, in such a way that in one setting position, the percussion drilling function is engaged and the blocking device is activated, and in the other setting position, the percussion drilling function is disengaged and the blocking device is deactivated. 
   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  is a fragmentary longitudinal section through a hand power tool; 
       FIG. 2  is a fragmentary perspective view of the hand power tool of  FIG. 1 ; 
       FIG. 3  is an exploded view of the hand power tool, without its power tool housing; 
       FIG. 4  is a perspective view of an assembly module in the exploded view of  FIG. 3 , with the blocking device activated; 
       FIG. 5  is a view identical to  FIG. 4 , with the blocking device deactivated; 
       FIG. 6  shows a detail VI of  FIG. 1 , showing the inactive blocking device; 
       FIG. 7  is the same view as in  FIG. 6 , with a blocking device activated by a torque adjusting ring of an operating mode setting device; 
       FIG. 8  is the same view as in  FIG. 6 , with a blocking device activated by a torque adjusting ring and a function adjusting ring of an operating mode setting device; 
       FIG. 9  is a perspective view of a control ring, cooperating with the torque adjuster for actuating the blocking device and preselecting the overlocking or overloading moment of an overlocking or overloading coupling; 
       FIG. 10  is a perspective view of an inner ring of the two-part function adjusting ring; 
       FIG. 11  is a perspective view of an assembly module comprising a threaded spindle of a cam device and its actuating unit; 
       FIG. 12  is a perspective view of the assembly module of  FIG. 11 , without the actuating unit; 
       FIG. 13  is a perspective view of an assembly module of the hand power tool, in a further exemplary embodiment, with a modified operating mode setting device; and 
       FIG. 14  is a perspective view of the torque adjusting ring, the function adjusting ring, and a covered disk of the operating mode setting device of  FIG. 13 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With the hand power tool shown in fragmentary form in longitudinal section in  FIG. 1  and without its housing in an exploded view in  FIG. 3 , also known as a drilling screwdriver, work can be done in three different types or modes of operation, namely in the “percussion drilling” operating mode, the “drilling” operating mode, and the “screwdriving” operating mode; in the “screwdriving” operating mode, a tightening torque in various magnitudes, specifically in fifteen different magnitudes in this exemplary embodiment, can be preselected. If this torque is exceeded, then an overlocking coupling becomes operative, and the screwdriver is not driven further. 
   The hand power tool has a power tool housing  10 , in which a rotationally drivable tool spindle  11  is rotatably supported. The tool spindle  11  protrudes from the face end of the power tool housing  10  and on its protruding end has a thread  12  onto which a tool holder, not shown here, can be screwed, in which holder a drill, screwdriver or percussion drill can be fastened. In the front region, a guide sleeve  13  is fixedly joined to the power tool housing  10 . The end of the guide sleeve  13  on the power takeoff side of the spindle is dynamically closed off from the rotating tool holder, for the sake of preventing the entry of dust, by means of a cap  60  with an integrated dust labyrinth  61  ( FIG. 1 ). 
   The tool spindle  11  is rotatably held in the guide sleeve  13  via a ball bearing  14 , on the one hand, and on the other, two rotatable adjusting rings of an operating mode setting device are located axially side by side on the guide sleeve  13 , for calling up the operating modes of the hand power tool. With the torque adjusting ring  15 , the “drilling” operating mode and the “screwdriving” operating mode are called up, and simultaneously in the “screwdriving” operating mode, the desired tightening torque for a screwdriver is preselected. With the function adjusting ring  16 , the “percussion drilling” operating mode is engaged and disengaged again. 
   The rotational drive of the tool spindle  11  is effected by an electric motor  17  ( FIG. 3 ) via a planetary gear  18 , which has a sun wheel  19 , seated on the tool spindle  11  in a manner fixed against relative rotation; planet wheels  20 , which mesh with the sun wheel  19  and are supported on a planet wheel carrier  21 ; and a ring gear  22 , whose internal toothing meshes with the planet wheels  20 . The ring gear  22 , together with a transmission ring  23  that is axially displaceably retained on the guide sleeve  13  and with a coupling spring  24 , embodied as a helical compression spring, that is slipped onto the guide sleeve  13 , forms an overlocking or overloading coupling  25 , in which transmission means, located on the face end of the ring gear  22  and the transmission ring  23 , are kept in engagement with one another by their pressure force of the coupling spring  24 . 
   As long as the torque or overlocking or overloading moment predetermined by the prestressing force of the coupling spring  24  is not attained, the ring gear  22  is held nonrotatably on the guide sleeve  13 , and the tool spindle  11  is driven via the planet wheel carrier  21 , which is braced on the tool spindle  11  and coupled to it in a manner fixed against relative rotation via a slaving means  26  ( FIGS. 1 and 3 ). If the overlocking moment that has been set is exceeded, the transmission means can overlock, by reverse displacement of the coupling spring  24 , and as a result the ring gear  22  is released and can rotate freely The rotary motion of the planet wheels  20  is now no longer transmitted to the planet wheel carrier  21 , and the tool spindle  11  is driveless. 
   The prestressing of the coupling spring  24  is preselected by the torque adjusting ring  15 . The torque adjusting ring  15  is capable of rotating a threaded ring  28 , specifically via a slaving means  27  ( FIG. 3 ) that protrudes axially from the threaded ring  28 . By means of a screw thread  29 , the threaded ring  28  is screwed onto the guide sleeve  13 , so that the threaded ring  28  upon rotating is axially displaced and changes the prestressing of the coupling spring  24 . The force of the coupling spring  24  is transmitted to the transmission ring  23  ( FIG. 3 ) and hence to the face end of the ring gear  22  via two disks  30 , which rest on three axially extending cams  231  of the transmission ring  23 . 
   For the “drilling” and “percussion drilling” operating modes, the overlocking or overloading coupling  25  must be switched to be inoperative; that is, the ring gear  22  that forms one coupling part is fixed on the guide sleeve  13  in a manner that prevents relative rotation, without the capability of overlocking or overloading. To that end, the ring gear  22 , on its outer circumference, has detent lugs  32 , offset from one another by the same circumferential angles, with detent gaps  33  located between them ( FIGS. 3 through 5 ), and the blocking device  31  has two slide wedges  34 , which are located on the guide sleeve  13  axially displaceably counter to a restoring spring  35 . On being axially displaced, the slide wedges  34  can each plunge in form-locking fashion into a respective detent gap  33  of the ring gear  22  and can thus bind the ring gear  22  to the guide sleeve  13  in a manner fixed against relative rotation. 
   The axial displacement of the slide wedges  34  is accomplished on the one hand by two control cams  36  on the threaded ring  28  ( FIG. 9 ), which are each located at the end of a control curve  37  on the annular end face of the threaded ring  28 . The slide wedges  34 , under the influence of their restoring springs  35 , rest on the two control curves  37 . As soon as the torque adjusting ring  15  rotated into its “drilling” setting position, the slide wedges  34 , by screwing the threaded ring  28  forward, run up onto the control cams  36  and are thereby thrust into the detent gaps  33  in the ring gear  22 , so that the ring gear is fixed on the guide sleeve  13  in a manner that prevents relative rotation. 
   The function adjusting ring  16 , which by rotation can be transferred into two setting positions, likewise accesses the blocking device  31 , specifically in such a way that in its “percussion drilling” setting position, it inserts the slide wedges  34 , counter to the force of the restoring spring  35 , into the detent gaps  33  in the ring gear  22 , and in its other setting position, it releases the slide wedges  34  again, so that they are thrust out of the detent gaps  33  by the restoring springs  35 , and the ring gear  22  now meshes with the transmission ring  23  of the overlocking or overloading coupling  25  solely via the transmission elements. 
   As can be seen from  FIGS. 1 and 3 , the function adjusting ring  16  is embodied in two parts and comprises an outer ring  161  and an inner ring  162 , which are joined together in a manner fixed against relative rotation. The inner ring  162  is rotatably supported on the guide sleeve  13  and achieves its axial bearing by means of a shell-like grasp  38  in the power tool housing  10 . The threaded ring  28 , rotating all the way around, is braced on the inside face of the inner ring  162 . The inner ring  162  ( FIG. 10 ), on its face end, has two control curves  39 , on one end of each of which an axially protruding control cam  40  is located. The two control cams  40  are positioned such that upon rotation of the function adjusting ring  16  into its “percussion drilling” setting position, the control cams  40  run onto the slide wedges  34  and push them into the detent gaps  33  in the ring gear  22 . 
   In  FIGS. 6 through 8 , the location of a slide wedge  34  in three different settings of the torque adjusting ring  15  and the function adjusting ring  16  is shown in fragmentary form. In  FIG. 6 , the blocking device  31  is inoperative. The slide wedges  34  have been pushed out of the detent gaps  33  of the ring gear  22 . This is the case whenever the torque adjusting ring  15  is in its “screwdriving” setting position with an arbitrary preselection of torque, and the function adjusting ring  16  is in its other setting position, or in other words not in the “percussion drilling” setting position. In  FIG. 7 , the torque adjusting ring  16  has been moved to its “drilling” setting position. The rotary position of the function adjusting ring  16  is unchanged. 
   The control cams  36  on the threaded ring  28  have thrust the slide wedges  34  into the detent gaps  33  of the ring gear  22  and keep the slide wedges  34  in this thrust-in position, counter to the force of their restoring spring  35 . In  FIG. 8 , the function adjusting ring  16  is additionally shown rotated into its “percussion drilling” setting position. The control cams  40  have pressed against the slide wedges  34  and hold them, as do the control cams  36  on the threaded ring  28 , in the inserted position on the ring gear  22 . If the torque adjusting ring  15  is now moved into its “screwdriving” setting position, then the control cams  36  on the threaded ring  28  lift away from the slide wedges  34  by axially reverse-screwing the threaded ring  28 . However, as before, the inner ring  162  keeps the slide wedges  34  in engagement with the ring gear  22  and presses the ring gear  22 , regardless of the rotary position of the torque adjusting ring  15 , firmly against the guide sleeve  13  in a manner fixed against relative rotation. 
   If the function adjusting ring  16  is returned to its other setting position, then the control cams  40  release the slide wedges  34 , and the slide wedges are expelled from the detent gaps  33  of the ring gear  22  by their restoring springs  35 . The hand power tool is in the operating mode that is predetermined by the instantaneous position of the torque adjusting ring  15 . As can be seen, by rotation of the function adjusting ring  16  into its “percussion drilling” setting position, the operating mode called up by the torque adjusting ring  15  is “overtaken” or overridden. The torque adjusting ring  15  can be rotated arbitrarily without becoming operative. Not until the function adjusting ring  16  has been reset to its other setting position does the torque adjusting ring  15  attain its described mode of operation. 
   For the “percussion drilling” operating mode, a cam device  41  ( FIGS. 1 ,  11  and  12 ) is provided on the tool spindle  11 , in a known manner. The cam device  41  has two cam disks  42 ,  43 , with cams oriented toward one another. One cam disk  42  is connected to the tool spindle  11  in a manner fixed against relative rotation, and the other cam disk  43  is limitedly axially displaceably embedded in the guide sleeve  13 . The cam disk  43 , on its side facing away from the cam disk  42 , has three pegs, which are offset from one another by equal circumferential angles and which protrude axially from the cam disk  43 . A compression spring  44  ( FIGS. 11 and 12 ) is slipped onto each peg. The pegs with compression springs  44  slipped onto them are received in corresponding blind bores in the guide sleeve  13 . The compression springs  44  are braced on the base of the blind bores and are compressed upon installation of the cam disk  43 , so that they act upon the cam disk  43  with an axial pressure force. 
   The cam disk  43  thus rests in its receptacle in the guide sleeve  13  in an axial floating way, prestressed toward the cam disk  42  and mechanically limited. The axially floating bearing of the cam disk  43  is necessary to assure continuous drilling in the percussion drilling mode. With a slight contact pressure force of the tool against the workpiece, the cam disk  42  comes into engagement with the detent cams on the cam disk  43 . However, the cam disk  43  can deflect axially counter to the prestressing force of the compression springs  44 . The compression spring packet thus has a damping effect and absorbs some of the vibrational energy, which is important for drilling against hard, brittle workpiece surfaces. If the full percussion drilling vibration is required, as for instance in making coarse bores in masonry, fine concrete, and the like, then the contact-pressure force of the tool must be increased maximally, as a result of which the compression springs  44  are overridden, and the cam disk  43  is pressed against its axial mechanical stop in the guide sleeve  13 . Thus the maximum possible undamped axial vibration energy reaches the drilling tool. 
   An actuating unit  45 , controlled by the function adjusting ring  16 , assures that when the function adjusting ring  16  is set to its “percussion drilling” setting position, the cam disks  42 ,  43  are brought into engagement with one another, and in the other setting position of the function adjusting ring  16 , they are put out of engagement again. As long as the cam disks  42 ,  43  are in engagement with one another, the tool spindle  11  is additionally subjected to percussion upon rotation. The actuating unit  45  ( FIGS. 3 and 11 ) has a control ring  46 , with axially protruding humps  47  offset from one another on the circumference; a control disk  48 , resting on the humps  47 , with slits  49 , offset by the same circumferential angles as the humps  47 , for the humps  47  to pass through; and a holder  50 , in which the ball bearing  14  of the tool spindle  11  is received. 
   The holder  50  has an annular bottom  501 , three retaining arms  502  protruding from it, and three overfitting tabs  503 , which are bent at the end of the retaining arms  502  and rest on the disk face, facing away from the humps  47 , of the control disk  48 . 
   In this position of the actuating unit  45 , the ball bearing  14  and the tool spindle  11  are displaced axially so far that the cam disk  42 , press-fitted onto the tool spindle  11 , is disengaged from the cam disk  43 . Upon rotation of the control disk  48 , which is done via a slaving means  51  ( FIG. 11 ), which is located on the control disk and is slaved by the function adjusting ring  16  upon the transfer of the function adjusting ring to the “percussion drilling” setting position, the slits  49  of the control disk  48  come to coincide with the humps  47  of the control ring  46 , so that these humps pass through the slits  49 , and the control disk  48  rests on the control ring  46 . As a result, the control disk  48 , the holder  50 , and the ball bearing  14  with the tool spindle  11  move axially jointly with one another, and as a result the cam disks  42 ,  43  come into engagement with one another in order to generate the percussion frequency. 
   As can be seen from  FIGS. 2 and 3 , markings  61  located side by side in the circumferential direction are located on the torque adjusting ring  15 , each indicating one setting position of the torque adjusting ring  15  for a defined magnitude of the overlocking (overloading) moment. For setting these setting positions, the torque adjusting ring  15  is detent-locked with an axially acting detent spring  52  and a detent disk  53  that is engaged axially on the inside by the detent spring  52 . The final setting position of the torque adjusting ring  15  in the direction of rotation is identified by a symbol for the “drilling” operating mode. 
   In the function adjusting ring  16 , there is a display window  54 , in which a red face appears when the function adjusting ring  16  is set to its “percussion drilling” setting position, and a triangle  55  with its triangular tip pointing toward the torque adjusting ring  15  appears when the function adjusting ring  16  is set to the other setting position. This triangular tip serves as a reference marking for the markings  61  on the torque adjusting ring  15  and points to the setting position, set by the torque adjusting ring  15 , which is indicated by the markings on the torque adjusting ring  15 . The two symbols “red face” and “triangle” are located on a curved flat segment  56  ( FIG. 3 ), which is thrust between the inner ring  162  and the outer ring  161  of the function adjusting ring  16  and is fixed on the guide sleeve  13  in a manner that prevents relative rotation. Depending on the rotary position of the function adjusting ring  16 , one symbol appears in the display window  54 , while the other symbol is covered by the outer ring  161 . 
   In the modified version of the torque adjusting ring  15 ′ and function adjusting ring  16 ′ shown in  FIG. 13  and  FIG. 14 , the function adjusting ring  16 ′ again has the display window  54 ′, but in the display window  54 ′, not only the setting positions of the function adjusting ring  16 ′ but also the setting positions of the torque adjusting ring  15 ′ are displayed. A flat segment  56 ′ is again located in the region under the display window  54 ′ and is retained in the guide sleeve  13  in a manner fixed against relative rotation. The flat segment  56 ′ has a painted-on hammer symbol  57  and a segment cutout  58 , whose dimensions correspond to those of the display window  54 ′. 
   The torque adjusting ring  15 ′ has an offset annular collar  59 , which the function adjusting ring  16 ′ fits over. Numbers are located side by side in the circumferential direction on the annular collar  59 , symbolizing the setting positions of the torque adjusting ring  15 ′ in which positions the overlocking (overloading) moment of the overlocking (overloading) coupling  25  is set with a deviating overlocking moment. The magnitude of the overlocking moment increases as the numbers become higher. At the end of the number scale, there is a symbol, not visible here, for the “drilling” setting position. 
   If the function adjusting ring  16 ′ is in its “percussion drilling” setting position, then the hammer symbol  57  becomes visible through the display window  54 ′. The hand power tool is in the “percussion drilling” operating mode. If the function adjusting ring  16 ′ is shifted from this setting position to its other setting position, then the display window  54 ′ comes to coincide with the segment cutout  58  in the flat segment  56 ′. Depending on which setting position the torque adjusting ring  15 ′ is set to, this setting position becomes visible in the display window  54 ′, such as the number “1” for a setting position in which the hand power tool is in the “screwdriving” operating mode with the least overlocking (overloading) moment, or the drilling symbol, for instance, on the annular collar  59  that shows that the hand power tool is in the “drilling” operating mode. 
   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 hand power tool, in particular drilling screwdriver, 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 reveal 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 the invention.