Abstract:
An electric power tool, in particular a drill/screwdriver, has a drive motor which is coupled via a gearbox to an output drive element. The gearbox has a plurality of gears. In particular, the drive motor is coupled to a drive spindle in which the torque generated by the drive motor is adjustable. The torque can be adjusted by a first, manually operated, adjusting device, and by a second, manually operated, adjusting device. The second adjusting device is configured to adjust the torque by selecting the gear of the gearbox. Both adjusting devices are operated by a common actuating element.

Description:
This application is a 35 U.S.C. §371 National Stage Application of PCT/EP2011/056029, filed on Apr. 15, 2011, which claims the benefit of priority to Serial No. DE 10 2010 029 267.2, filed on May 25, 2010 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND 
     The disclosure relates to an electric power tool, in particular a drill/screwdriver, as described below. 
     Such an electric power tool is known from DE 10 2004 051 911 A1 of the applicant. The known electric power tool in that case has two positioning rings, realized as separate actuating elements, the first positioning ring being used for the operating mode “drilling” and “screwdriving” with the possibility of setting a maximum torque to be transmitted, and the other positioning ring being used to set a percussion drilling function. For the purpose of setting and changing operating parameters in differing types of operation, therefore, the operator has to operate two actuating elements, or positioning rings, that are separate from each other, only one of the actuating elements being active in each case. Operation therefore requires knowledge of the functionality of the two actuating elements. Furthermore, the known electric power tool has a relatively elaborate structure, owing to the two positioning rings, and the arrangement of the two actuating elements requires a relatively large amount of structural space. 
     SUMMARY 
     Starting from the prior art described, the disclosure is based on the object of developing an electric power tool, in particular a drill/screwdriver, as described below, in such a way that its structure is simplified through a reduction of adjusting elements and, at the same time, operation is made relatively easy for the operator. This object is achieved in the case of an electric power tool, in particular a drill/screwdriver, having the features described below. The disclosure in this case is based on the idea of actuating both adjusting devices for the respective operating modes via a common actuating element. In other words, this means that two adjusting devices can be actuated in differing operating modes by means of a single actuating element. Consequently, compared with the prior art, a simplified structure is achieved because of a reduction in the number of components. At the same time, the operation of the two adjusting devices is simplified. In addition, the disclosure has the advantage that, owing to the saving in operating elements, a particularly compact structure of the electric power tool can be achieved, since only structural space for a single actuating element is required. 
     Advantageous developments of the electric power tool according to the disclosure are specified below. All combinations of at least two features disclosed, the description and/or the figures are included within the scope of the disclosure. 
     In a configuration implementation of the disclosure that provides a high degree of robustness of the electric power tool, in particular of the actuating element, it is proposed that the actuating element is realized as a mechanical actuating element in the form of a sliding or rotary switch. 
     In order, on the one hand, to provide for unambiguous assignment to the individual adjusting devices in the actuation of the actuating element, the assignment being, moreover, easily understood by an operator, it is additionally proposed that the actuating element has a first adjustment range, in which the actuating element acts exclusively in combination with the first adjusting device, and has a second adjusting range, which adjoins the first adjusting range and in which the actuating element acts exclusively in combination with the second adjusting device. 
     To enable the position of the actuating element for the first adjusting device to be identified in a simple and stepless manner, it is proposed, in a preferred embodiment of the disclosure, that the first adjusting device, for the purpose of torque setting, comprises a potentiometer for identifying the position of the actuating element, the resistance value of which potentiometer can be varied by means of a contact element that is arranged on the actuating element and that acts as a jumper between printed conductors. 
     Also preferred is an embodiment in which the position of the actuating element is represented by means of an optical indicator. Such an optical indicator can be seen relatively easily by an operator, and thus enables the desired switching position of the actuating element to be set particularly accurately. 
     It is particularly preferred in this case if the optical indicator is arranged in the region of the adjustment path of a control element of the actuating element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, features and details of the disclosure are given by the following description of preferred exemplary embodiments and with reference to the drawings. 
       In the drawings: 
         FIG. 1  shows a perspective view of an electric power tool according to the disclosure, in the form of a drill/screwdriver, 
         FIG. 2  shows a perspective partial view of the drill/screwdriver according to  FIG. 1 , in the region of its actuating element, 
         FIG. 3  and 
         FIG. 4  show a perspective, partially sectional view of the electric power tool in the region of the first adjusting device, from differing perspectives, 
         FIG. 5  shows a longitudinal section through the electric power tool in the region of the adjusting devices, 
         FIG. 6  shows a perspective view of a part of the actuating element realized as an adjusting ring, 
         FIG. 7  shows a perspective view of individual parts of the second adjusting device, 
         FIG. 8  and 
         FIG. 9  show the second adjusting device in a mounted state, in differing operating positions, and 
         FIG. 10  shows a perspective view of the electric power tool in the region of the actuating element, the actuating element being in the drilling position. 
     
    
    
     DETAILED DESCRIPTION 
     In the figures, components that are the same, or that have the same function, are denoted by identical reference numerals in each case. 
       FIG. 1  shows an electric power tool  10  according to the disclosure, in the form of a battery-operated drill/screwdriver  1 . In a manner known per se, the electric power tool  10  has a drive motor  11 , which acts upon a drive spindle  13  via a transmission  12 . Further, the transmission  12  of the electric power tool  10  has at least two gear stages (not represented), of which the first gear stage, which has a higher reduction ratio than the second gear stage, is used for screwdriving, while the second gear stage is suitable for drilling. What is then essential is that the maximum torque of the drive motor  11  that is to be transmitted to the drive spindle  13  can be set for the screwdriving function. 
     According to the disclosure, it is provided that both the setting of the maximum torque to be transmitted during screwdriving operation mode and the gear change necessary for shifting from screwdriving operation into drilling operation are effected by means of a single actuating element  15 . In this case, in the exemplary embodiment represented, the actuating element  15  is realized as a sliding switch realized as a rotary ring  16 . In addition, it is to be mentioned that the actuating element  15  could also be realized as a rotary switch, instead of as a rotary ring  16 . 
     The rotary ring  16  adjustable within a defined rotary angle range, in the housing of the drill/screwdriver  1 . A control element  17  is used for this purpose, which can be actuated by an operator from the outside, and which is preferably steplessly adjustable within the adjustment range, or rotary angle range, of the rotary ring  16 . The respective position of the control element  17 , or of the rotary ring  16 , is indicated by means of an optical indicator  18 . The optical indicator  18  in this case comprises two indicator fields  19 ,  20 , arranged separately from each other, in which there are arranged, in particular, a multiplicity of LEDs. What is essential in this case is that, in the one indicator field  19 , there is the actuating element  15  in the activated first operating mode, in which the drill/screwdriver  1  enables screwdriving operation, while the second indicator field  20  serves to indicate drilling operation. The arrangement of the indicator fields  19 ,  20  is such that the respectively illuminated LEDs correlate to, or are aligned with, the position of the operating element  17 . 
     As can be seen, in particular, from  FIGS. 3 and 4 , the rotary ring  16  has, on one outside face, an electrically acting contact element  22 , which is received in a positive manner in a preferably molded on recess on the rotary ring  16 . The contact element  22  is a constituent part of a potentiometer  25 , which is realized on an arcuate circuit board  26 . The circuit board  26 , in turn, is connected to a circuit carrier  27 , on which there are arranged evaluating means  28  suitable for acquiring the position of the contact element  22  relative to the circuit board  26 . For this purpose, the circuit board  26  has two printed conductors  29 ,  30 , which are arranged at a distance apart from each other and which are electrically jumpered by means of the contact element  22 . The position of the contact element  22 , and therefore the rotary angle position of rotary ring  16 , is acquired in that, according to the position of the rotary ring  16 , the contact element  22  likewise assumes an unambiguous position that corresponds to the position of the rotary ring  16 . The contact element  22  in this case jumpers the two printed conductors  29 ,  30  on the circuit board  26 , such that the potentiometer  25  generates a quite particular resistance value, which is acquired by means of the evaluating means  28 . This acquired value of the rotary angle position of the rotary ring  16  is supplied, as an input value, by the evaluating means  28  to a control device of the electric power tool  10 , which control device, not represented in the figures, by limiting the current of the drive motor  11 , on the basis of the position of the rotary ring  16  and, if appropriate, on the basis of other, additional input quantities, sets the maximum torque of the drive motor  1  to be transmitted. 
       FIG. 6  shows the outside face of the rotary ring  16  that is opposite the contact element  22 . In this case, latching cams  31  are formed on the rotary ring  16 , which latching cams act in combination with corresponding counter means, for example in the housing, upon a rotation of the rotary ring  16  and create for the operator, on the one hand, a latching that can be sensed haptically as the rotary ring  16  is being rotated and, on the other hand, a corresponding sound that can be perceived by the operator. 
     Moreover, it can be seen that an adjusting element, in the form of an adjusting pin  33 , is formed on the rotary ring  16 . The adjusting pin  33  is a constituent part of a gear step preselector switch  34  that, according to  FIGS. 7 to 9 , comprises a guide housing  35 , which is arranged in a fixed manner in the electric power tool  10 , and in which there is arranged a transmission plate  37  that slides according to the double arrow  36 , perpendicularly in relation to the direction of rotation of the rotary ring  16 , the direction of rotation of which is denoted by the double arrow  32 . Realized in the transmission plate  37  there is a guide slot  38  for the adjusting pin  33 , which guide slot is open at one of its ends  39 . On its top side, the transmission plate  37  has a latching cam  40 , which acts in combination with two latching cleats  44 ,  45  formed integrally on the guide housing  35 . The latching cam  40  in this case, according to the position in the transmission plate  37 , assumes two positions, represented in  FIGS. 8 and 9 , in which the transmission plate  37 , by means of a switching lever  41  coupled to the transmission plate  37 , sets the transmission  12  of the electric power tool  10  either in the first gear step  46  (shown schematically in  FIG. 5 ), which is provided for screwdriving, or in the second gear step  47  (shown schematically in  FIG. 5 ), which is suitable for drilling. In this case, the adjustment between the two positions, i.e. the respective overcoming of the latching cleats  44 ,  45  ( FIGS. 8 and 9 ) by the latching cams  40 , can be perceived both haptically and acoustically by the operator. 
     The gear step preselector switch  34  functions in the following manner: in the position of the rotary ring  16  in which the contact element  22  is located in the region of the printed conductors  29 ,  30  of the potentiometer  25 , which is equivalent to a first adjustment range  42  ( FIG. 2 ) of the rotary ring  16  for the screwdriving mode, the adjusting pin  33  is not in engagement with the guide slot  38  of the transmission plate  37 . This means that the switching lever  41  assumes a position in which the transmission  12  of the electric power tool  10  is in the first gear step  46 . Upon a rotation of the rotary ring  16  beyond the range of the potentiometer  25 , which is equivalent to a second adjustment range  43 , the adjusting pin  33  comes into engagement with the guide slot  38  of the transmission plate  37 . In this case, the direction of motion of the adjusting pin  33  is denoted in  FIG. 7  by the double arrow  32 , as is the direction of motion of the rotary ring  16 . As soon as the adjusting pin  33  is in engagement with the guide slot  38  of the transmission plate  37 , the latter is moved out of the guide housing  35 , such that the latching cam  40  and the switching lever  41  that is coupled to the transmission plate  37  assume their second position, represented in  FIG. 9 , in which the transmission plate  37  switches the transmission  12  of the electric power tool  10  into the second gear step  47 , by means of the switching lever  41 . The rotational speed is thereby increased, such that the electric power tool  10  is in the drilling mode. Upon a movement of the adjusting ring  16  out of the second adjustment range  43  back into the first adjustment range  42 , the transmission  12  is again adjusted from the second gear step to  47  the first gear step  46  by the switching lever  41 . 
     The electric power tool  10  described thus far can be modified in a multiplicity of ways without departure from the concept of the disclosure. This concept consists in providing a single actuating element  15  that is used for actuating differing functions on the electric power tool  10 .