Abstract:
The invention relates to a hand machine tool, in particular, a hammer drill or chisel, having a gearbox housing and a gearbox unit with a switching device. The switching device includes a switching spring and an operating unit which may be mounted in the gearbox housing with a transfer element. According to the invention, the switching spring has a housing region provided for housing the transfer element of the assembled operating unit, on assembly of the gearbox housing and the gearbox unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP2008/051473 filed on Feb. 7, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is based on a hand-held power tool. 
     2. Description of the Prior Art 
     There is already a known hand-held power tool that has a transmission housing and a transmission unit equipped with a switch device. The switch device also has a switch spring and an actuating unit, which can be mounted in the transmission housing and is equipped with a transmitting element. 
     ADVANTAGES AND SUMMARY OF THE INVENTION 
     The invention is based on a hand-held power tool, in particular a rotary hammer and/or a hammer chisel, having a transmission housing and a transmission unit equipped with a switch device that has a switch spring and an actuating unit, which can be mounted in the transmission housing and is equipped with a transmitting element. 
     According to one proposed embodiment, the switch spring has a receiving region provided to accommodate the transmitting element of the assembled actuating unit upon assembly of the transmission housing and transmission unit. In this context, the expression “assembly of the transmission housing and transmission unit” is understood in particular to mean a sliding of the transmission housing onto the transmission unit in a preferred assembly direction or a sliding of the transmission unit into the transmission housing in a preferred assembly direction. With the embodiment of the hand-held power tool according to the invention, it is possible to achieve a structurally simple mounting of the switch spring on the actuating unit during a simultaneous assembly of the transmission housing and transmission unit. This can be achieved in a particularly advantageous fashion if the switch spring has at least two spring legs that define the receiving region. Preferably, after an assembly of the transmission housing and transmission unit, the actuating unit is ready for operation, situated in a first switched position. The actuating unit is advantageously provided for switching between at least two different switched positions. 
     According to another proposed embodiment, the two spring legs are spaced apart from each other perpendicular to an assembly direction, making it possible to achieve a low-wear insertion of the actuating unit into the receiving region of the switch spring. The term “assembly direction” here is understood in particular to mean a direction in which a translatory relative movement of the transmission housing in relation to the transmission unit occurs during assembly of the transmission housing with the transmission unit. 
     If the spring legs are provided to move in an axial direction of at least one switch element of the transmission unit when the actuating unit is moved in a rotation direction, then this makes it possible to achieve an advantageous transformation of a switching motion, eliminating the need for additional parts. 
     According to another proposed embodiment of the invention, the switch spring constitutes at least one energy storage mechanism in which a switching force can be stored, thus making it advantageously possible to achieve a particularly low-wear switching between two switch elements that have switched positions synchronous to each other. If the two switch elements are situated in a position in which they are rotationally offset from each other, the switching force can be advantageously stored in the switch spring until the two switch elements assume synchronous switched positions at which point one of the two switch elements can be slid toward the other switch element because of the stored switching force, thus permitting the two switch elements to engage with each other in order to carry out a torque transmission. 
     According to another proposed embodiment of the invention, at least one spring leg of the switch spring has a switching bevel against which the transmitting element presses during at least one switching procedure, making it possible to achieve a structurally simple axial movement of a switch element connected to the switch spring during a rotating movement of the actuating unit. This can be achieved in a particularly advantageous fashion if the switching bevel of the spring leg has at least one guide surface for guiding the transmitting element. 
     According to another proposed embodiment of the invention, the two spring legs each have a respective leg region and the two leg regions are situated in a region of the transmitting element, in a plane parallel to the assembly direction, permitting the transmitting element to transmit a movement, in particular a rotating movement of the actuating unit, to the switch spring or more precisely, the spring legs, in a particularly simple fashion. 
     If the switch spring also has a subregion for accommodating a switch element of the transmission unit, then it is possible to advantageously achieve a direct coupling to the switch element, eliminating the need for additional parts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment taken in conjunction with the drawings, in which: 
         FIG. 1  shows a hand-held power tool according to the invention, equipped with a switch device, 
         FIG. 2  shows a section through a subregion of the hand-held power tool, equipped with a transmission unit and a transmission housing, 
         FIG. 3  is a side view of the switch device, 
         FIG. 4  is a perspective view of the switch device, and 
         FIG. 5  shows perspective views of the switch device and the transmission unit in a first switched position ( FIG. 5   a ) and in a second switched position ( FIG. 5   b ). 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a hand-held power tool  10  embodied in the form of a rotary hammer. The hand-held power tool  10  includes a housing  54  with a transmission housing  12  and, in a front region, a tool holder  56  for holding a tool. At an end oriented away from the front region, the hand-held power tool  10  has a main handle  58  for actuating the hand-held power tool  10  and for transmitting force from an operator to the hand-held power tool  10 . The hand-held power tool  10  has a drive unit  60  comprised of an electric motor to produce a drive moment. The drive torque of the drive unit  60  is transmitted via an intermediate shaft  62  of the hand-held power tool to an impact mechanism  64 , which is only partially shown in  FIG. 2  for the sake of visibility, and/or to a rotating output element constituted by a hammer tube  66  ( FIG. 2 ). In order to switch between different drive speeds and/or drive modes of a tool in the tool holder  56 , the hand-held power tool  10  has a switch device  16  equipped with an actuating unit  20  that includes a selector knob  68 . 
       FIG. 2  shows a subregion of the handheld power tool  10 , having a transmission unit  14  with the switch device  16  and having the transmission housing  12 . The switch device  16  for switching between different transmission stages of the transmission unit  14  has a switch spring  18  and the actuating unit mounted in the transmission housing  12 . To this end, the switch spring  18  transmits a rotating movement of the actuating unit  20  to an axially movable switch element  36  embodied in the form of a switching plate belonging to the transmission unit  14 . The switch spring  18  has two spring legs  26 ,  28  that define a receiving region  24  for accommodating a transmitting element  22  of the actuating unit  20 . The transmitting element  22  is embodied in the shape of a bar and is situated on the actuating unit  20 , extending in a direction of a rotation axis  72  of the actuating unit  20 , eccentric to the rotation axis  72 , on an inner side  70  of the actuating unit  20  oriented away from the selector knob  68  ( FIGS. 2 and 3 ). When the operator of the hand-held power tool  10  actuates the switch or more precisely, executes a rotating movement of the actuating unit  20 , the bar-shaped transmitting element  22 , which is arranged eccentric to the rotation axis  72 , transmits a force to one of the two spring legs  26 ,  28  of the switch spring  18  ( FIGS. 2 through 5 ). 
     Upon assembly of the transmission housing  12  and the transmission unit  14  in an assembly direction  30  pointing perpendicularly into the plane of the drawing in  FIG. 2 , the receiving region  24  for accommodating the transmitting element  22  makes it possible to move the transmission housing  12  in relation to the transmission unit  14  and to slide the transmission housing  12 , together with the actuating unit  20  that has already been mounted into it, onto the transmission unit  14 . To this end, the two spring legs  26 ,  28  of the switch spring  18  are spaced apart from each other perpendicular to the assembly direction  30 . The two spring legs  26 ,  28  are thus spaced apart from each other in a direction  74  that is oriented essentially perpendicular to the rotation axis  72  and perpendicular to the assembly direction  30 . In addition, the two spring legs  26 ,  28  are situated spaced apart from each other parallel to the rotation axis  72 . 
     In order for the switch spring  18  to transmit a force to the switch element  36  during a switching movement or more precisely during a rotating movement of the actuating unit  20 , the switch spring  18  has a subregion  52  composed of a helical spring ( FIGS. 2 through 4 ). The subregion  52  with the helical spring here encloses a receiving region for accommodating the switch element  36 . To this end, the switch element  36  has a bar-shaped coupling element  76  on a side  78  oriented toward the actuating unit  20  ( FIG. 3 ). The two spring legs  26 ,  28  each have a respective first leg region  80 ,  82  that extends in the direction  74  from the subregion  52  with the helical spring ( FIGS. 3 through 5 ). The first leg region  80  of the first spring leg  26  in the assembly direction  30  is longer in the direction  74  than the first leg region  82  of the second spring leg  28  in the assembly direction  30 . The first leg region  82  of the second spring leg  28  is adjoined by a second leg region  84 , which is perpendicular to the first leg region  82  and extends toward the actuating element  20  in a direction of a superposition of the assembly direction  30  and the rotation axis  72 . In addition, the second spring leg  28  has a third leg region  86  that adjoins the second leg region  84  and extends perpendicular to the second leg region  84  in the direction  74 . The third leg region  86  rests against the transmitting element  22  of the actuating unit  20 , after the transmitting element  22  in the assembly direction  30 . 
     The first leg region  80  of the first spring leg  26  is perpendicularly adjoined by a second leg region  88  that extends parallel to the rotation axis  72 , toward the actuating unit  20 . The second leg region  88  of the first spring leg  26  is perpendicularly adjoined by a third leg region  90  that extends at first parallel to the assembly direction  30 . The third leg region  90  of the first spring leg  26  also includes a switching bevel  42  that, in addition to a span component oriented in the assembly direction  30 , has a span component oriented in the direction  74 . The third leg region  90  is adjoined by a fourth leg region  92  of the first spring leg  26  that extends in direction  74 . The fourth leg region  92  of the first spring leg  26  and the third leg region  86  of the second spring leg  28  are essentially situated in a plane that extends parallel to the assembly direction  30 . 
     When an operator of the hand-held power tool  10  actuates the switch or more precisely, moves the actuating unit  20  in a rotation direction  32 , the switch spring  18  moves the switch element  36  in an axial direction  34 . To this end, the switch element  36  is supported so that it is able to move on a guide rod  94  of the transmission unit  14  in the axial direction  34 , which extends parallel to the assembly direction  30  ( FIGS. 5   a  and  5   b ). The switch element  36  has two annular regions  96  that are provided to accommodate the guide rod  94 . The two regions  96  are situated on the switch element  36 , one after the other along the guide rod  94 . In order to limit a movement of the switch element  36  on the guide rod  94  in a direction  98 , the guide rod  94  is equipped with a stop element  100  embodied in the form of a snap ring that is affixed to the guide rod  94 . The switch element  36  also has a coupling region  102  provided for coupling it to the transmission element  104  of the transmission unit  14  embodied in the form of a gear unit ( FIGS. 3 through 5 ). The transmission element  104  of the transmission unit is supported so that it is able to move in the axial direction  34  on the intermediate shaft  62  in order to switch between the different transmission stages. To permit a coupling of the switch element  36  to the transmission element  104 , the transmission element  104  has a receiving groove  106  that is engaged by the coupling region  102  of the switch element  36 . 
     To guide and support the two spring legs  26 ,  28  on the switch element  36 , the switch element  36  has a subregion  108  that extends essentially parallel to the assembly direction  30  and essentially parallel to the rotation axis  72 . The two spring legs  26 ,  28  are guided between the subregion  108  and the guide rod  94 . In the axial direction  34 , the switch element  36  also has a lateral flank  110  on both a side oriented toward the stop element  100  and a side oriented away from the stop element  100 ; these flanks, together with the subregion  108  and the guide rod  94 , hold the two spring legs  26 ,  28  in a desired position. 
       FIG. 5   a  shows a first switched position of the actuating unit  20  and the switch element  36  on the guide rod  94 . In the first switched position, the transmitting element  22  of the actuating unit  20  rests against the third leg region  86  of the second spring leg  28 . The switch element  36  here is situated in an end position resting against the stop element  100  on the guide rod  94 . The transmission element  104  of the transmission unit  14  has one gear  112  for transmitting a drive moment to the hammer tube  66  and a second gear  114 , which, in a second switched position of the switch element  36  and actuating unit  20 , can be coupled to a second gear unit  116  of the transmission unit  14  that is rotatably supported on the intermediate shaft  62 . 
     With a rotation of the actuating unit  20  in the rotation direction  32  from a first switched position into a second switched position ( FIGS. 5   a  and  5   b ), the transmitting element  22  of the actuating unit  20  moves along an arc toward the third leg region  90  of the first spring leg  26 . As soon as the transmitting element  22  comes into contact with the switching bevel  42  of the third leg region  90 , the transmitting element  22  exerts a pressure in the direction opposite from the direction  98  on the first spring leg  26 , causing the switch spring  18  and the switch element  36  to move on the guide rod  94  in the axial direction  34  opposite from the direction  98 . On a side oriented toward the transmitting element  22 , the switching bevel  42  has a guide surface  44  that guides the transmitting element  22  into the second switched position while at the same time, the switch element  36  moves farther on the guide rod  94  in the direction opposite from the direction  98 . If the actuating unit  20  and the transmitting element  22  are situated in the second switched position ( FIG. 5   b ), then the fourth leg region  92  of the first spring leg  26  rests against the transmitting element  22 , thus preventing the switch spring  18  and switch element  36  from moving back out of the second switched position in an undesirable fashion. In the second switched position, the second gear  114  of the transmission element  104  engages with an inner contour  118  of the second gear unit  116  that corresponds to the second gear  114 . When switching from the first switched position into the second switched position, if a switching path of the switch element  36  is blocked—i.e. the second gear  114  of the transmission element  104  and the inner contour  118  are in a rotationally offset position in relation to each other that prevents the second gear  114  from engaging in the inner contour  118 —then the switch spring  18  functions as an energy storage means  38  in which a switching force for moving the transmission element  104  into the second switched position can be stored. As soon as the switching path is free—i.e. the second gear  114  and the inner contour  118  of the second gear unit  116  are in a coinciding, synchronous position—the movement energy of the switch spring  18  is then transmitted to the switch element  36  so that the switch element  36 , together with the transmission element  104 , is moved farther in the direction opposite from the direction  98  and the second gear  114  engages with an inner contour  118  of the second gear unit  116 . 
     If the actuating unit  20  is rotated from the second switched position into the first switched position in the rotation direction  32 , then the transmitting element  22  presses against the third leg region  86  of the second spring leg  28 , thus moving the switch spring  18 —and together with it, the switch element  36  on the guide rod  94  and the transmission element  104  on the intermediate shaft  62 —in the direction  98 . During the switching procedure, the transmitting element  22  moves from an end region of the third leg region  86  remote from the second leg region  84  of the second spring leg  28  to an end region of the third leg region  86  close to the second leg region  84 . If the actuating unit  20  and the transmitting element  22  are in the first switched position, then the switch element  36  on the guide rod  94  is in the end position oriented closer to the stop element  100 . 
     The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.