WO2009156004A1

WO2009156004A1 - Power tool having an adjustable clutch device and method for operating the same

Info

Publication number: WO2009156004A1
Application number: PCT/EP2008/066315
Authority: WO
Inventors: Gerhard Meixner; Willy Braun; Juergen Lennartz
Original assignee: Robert Bosch Gmbh
Priority date: 2008-06-24
Filing date: 2008-11-27
Publication date: 2009-12-30
Also published as: DE102008002589A1; EP2303513A1

Abstract

The invention relates to a power tool having at least one tool drive shaft (23, 323) for rotationally driving a tool insert (17, 317) changeably received in a tool receptacle of a tool holder (16, 316) and having at least one drive device (14, 314) comprising a gearbox device (20, 320). The power tool has a device for changing operational modes (15, 315) having an operational mode switching element (13, 13a, 313, 313a) for switching between different operational modes provided for the power tool. At least one adjustable clutch device (44, 45, 344, 345) couples the at least one tool drive shaft (23, 323) to the at least one drive device (14, 314) and comprises at least two different limit torques that can be selected by means of a torque selecting device (97, 397). The invention proposes that at least one active component (186, 486) operationally connects the torque selecting device (97, 397) to the device for changing operational modes (15, 315), particularly to the operational mode switching element (13, 13a, 313, 313a), such that the torque selecting device (97, 397) can be actuated by means of the operational mode switching element (13, 13a, 313, 313a).

Description

title

Machine tool with an adjustable coupling device and method of operation

State of the art

The invention relates to a machine tool, in particular an electrically operable hand tool according to the preamble of the independent claims.

Machine tools which serve at least one rotary drive of insert tools usually have latching clutches which limit a torque acting on the insert tool to a specific, preselected limit torque. Especially in portable power tools with powerful rotary drives such. Drilling machines, percussion drills or drilling / combi hammers is the pre-selected limit torque and thus the Überrastkupplung a significant importance in accident prevention. Usually, the preselected limit torque represents a compromise between the lowest possible torque load of the insert tool, the machine tool and / or an operator and the highest possible working torque for using large tool diameter of the insert tool.

In order to meet different work situations, Überrastkupplungen or coupling devices with adjustable limit torques offer. From DE 43 04 899 A1 a rotary hammer is known as an example of a hand tool machine, in which at least two separate clutches are provided in the transmission device between a drive source and a rotationally drivable tool holder. The couplings have different limit torques and can be brought into engagement independently by the operator, so that when using the hammer drill different limit torques can be effective. In addition, there are already various embodiments of two-stage

Coupling devices known. Thus, from DE 38 32 302 C1 discloses a coupling device with two coupled, serially arranged on a shaft locking clutches known. The Überrastkupplungen be connected via a switchable, axially displaceable pin, which is arranged in a radially outer region of the Überrastkupplungen, selectively connected to each other and / or fixed to a housing, so that relative to the shaft different limit torques are effective.

From DE 101 30 520 A1 a coupling device with a Überrastkupplung for hand tool machines is also known, in which a control over the Limit torque of Überrastkupplung can be adjusted. The Überrastkupplung has to radially arranged, set to a biasing force spring elements for generating a Überrastdrehmoments whose biasing force is variable via control. Many known machine tools also have an operating mode switching device, with which it is possible to switch between at least two different operating modes for the drive of the insert tool. Thus, for example from DE 10 2004 055 236 A1 a rotary hammer is known in which are switched over the operating mode switching between an oscillating axial drive, a combined axial-rotary drive and a rotary drive of the insert tool. This corresponds to the operating modes chiseling, impact drilling and drilling of the hammer drill.

Advantages of the invention

The machine tool according to the invention with the characterizing features of the main claim has the advantage that no additional switching element on the housing of the machine tool is necessary for operating the torque selection device of the adjustable coupling device by the operator. This increases on the one hand the ease of use and operating safety and on the other hand leads to a housing on the compact design. In particular, it is ensured in this way that an increased limit torque can only be selected in operating modes such as, for example, drilling and / or percussion drilling of a hammer drill according to the invention. Regarding modes that differ by different types of drive the insert tool, this can also be spoken of basic modes.

The measures listed in the dependent claims, advantageous refinements and improvements of the main claim features. Advantageously, in at least one of the different operating modes of the machine tool, the selectable limit torque of the adjustable coupling device can be set via the operating mode switching element. In particular, the selectable limit torque is adjustable in at least one basic mode by the mode switching element. Preferably, this basic mode corresponds to at least one rotary drive of the insert tool.

In a preferred embodiment, the transmission device of the machine tool according to the invention comprises an output unit which is provided for an oscillating axial drive of the insertion tool. With the operating mode switching device can be switched between at least two modes, especially basic modes. The switchable operating modes consist of a pure axial drive, a combined axial-rotation drive and / or at least one pure rotary drive.

If the transmission device is designed as a two- or multi-speed transmission device for the rotary drive of the insert tool, a particularly efficient embodiment of the machine tool according to the invention is possible by the development of the invention described below. The two- or multi-speed transmission device provides divergent, switchable gear ratios between an input side and an output side. A first operating mode, in particular the first basic operating mode, of the machine tool is designed as a rotary drive in a first gear with a first gear ratio. At least one further, preferably operating mode, in particular basic operating mode, is designed as a rotary drive of the insert tool in a second gear with a second gear ratio.

In a preferred refinement of this embodiment, the transmission device transmits the greatest possible torque between the input side and the output side in first gear. Preferably, in the first mode, in particular the first basic mode, the selectable limit torque of the adjustable coupling device via the mode switching element is adjustable.

In another advantageous development, a first limit torque MG1 of the at least two limit torques of the adjustable clutch device is smaller than the at least one second limit torque MG2. In particular, the first limit torque MG1 corresponds to the lowest possible limit torque MGmin of the adjustable clutch device.

If the torque selection device of the adjustable coupling device has at least two switching positions SP1, SP2, a robust embodiment of the machine tool according to the invention is achieved. In this case, a first shift position SP1 is preferably provided, in which the first limit torque MG1, in particular the lowest possible limit torque MGmin of the adjustable clutch device is selected.

In a cost-effective embodiment of a machine tool according to the invention, the mode switching element is designed as a mechanical switching element. In this case, the mechanical switching element can be designed in particular as a sliding, rotating, tilting or pressure switching element.

In a particularly cost-effective embodiment of a machine tool according to the invention, the operating mode switching device is designed essentially as a mechanical switching device. In a particularly effective embodiment, the operating mode switching device has an electrically drivable actuator.

If the mode switching element is designed as an electromechanical and / or electronic switching element, it is possible to achieve a particularly flexible design of a machine tool according to the invention.

Further cost savings can be achieved if the active agent has at least one mechanical element, preferably consists of such an element. In this case, the mechanical element may in particular be a spring, lever, pressure, sliding and / or tension element. In a particularly flexible embodiment of the machine tool according to the invention, the active agent comprises an electrically drivable actuator, in particular an electromagnet and / or a piezoelectric element.

Another aspect of the invention consists in a method for operating a machine tool having at least one, driven by a drive device tool drive shaft for the rotary drive of an insert tool. The insert tool is exchangeably received in a tool holder of a tool holder. In addition, the machine tool is equipped with an operating mode switching element having operating switching device for switching between different - in particular at least two different - provided on the machine tool operating modes. The at least one tool drive shaft is coupled via an adjustable coupling device with the drive device, wherein the adjustable coupling device has at least two different, selectable via a torque selector limit torque MG1, MG2. In particular, the method relates to the operation of a machine tool, as known from the foregoing description. The operating mode switching device has at least one, in particular at least one additional operating mode for each selectable limit torque MG1, MG2 of the adjustable clutch device. The inventive method is characterized in that for selecting a limit torque of the adjustable coupling device by an operator on the mode switching element, a, the selected limit torque corresponding mode MOD_Soll is set. The setting of the operating mode MOD_Soll on the operating mode switching element by the operator represents a first step S1 of the method according to the invention.

In a second step S2, the torque selection device of the coupling device is set, in particular automatically adjusted so that the set Limit torque MGJst the coupling device corresponds to the desired limit torque MG_Soll.

In a preferred further development, a substep TS1 is provided between steps S1 and S2. In this sub-step TS1 is checked, in particular automatically checked whether in the selected mode MOD_Soll the torque selector device of the coupling device to be adjusted.

In another modification of the method according to the invention, a sub-step S2 is provided between steps S1 and S2, in which checks, in particular automatically checks whether a limit torque MGJst is already set to the coupling device, which corresponds to the limit torque MG_Soll the selected mode MOD_Soll.

A particularly advantageous further development of the method according to the invention has a provision, in particular an automatic return of the adjustable coupling device to a low, in particular the lowest possible limit torque MGmin. The provision is made when the insert tool by the operator from and / or in the tool holder of the tool holder off and / or introduced. In particular, the provision is constructed as a secondary process, which monitors the insertion and / or execution of the tool by the operator in a first partial step ZS1. In a second substep ZS2, the limit torque MG_Soll to be set is set to a lower, preferably the lowest possible limit torque MGmin, and finally step S2 is triggered.

A preferred further development is a third partial step ZS3. In this sub-step ZS3 a reset takes place, in particular an automatic reset of the mode switching element in an operating mode corresponding to the lowest possible limit torque MGmin.

Further advantages, modifications and further developments of the machine tool according to the invention and / or the method according to the invention will become apparent from the following description of the embodiments.

Description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. Show it:

Fig. 1 is an external view of a rotary hammer of the prior art Fig. 2 shows a rotary hammer as the first embodiment in side view 3 is an enlarged detail of the hammer drill on Fig. 2nd

4a is a plan view of a coupling device along the section line A - A of Fig. 2nd

Fig. 4b is a plan view of an alternative coupling device analogous to Fig. 4a

5a to 5d an alternative embodiment of a coupling device with an alternative variant of a mechanical actuator in different views

6a and 6b are each a side sectional view of the coupling device of Fig. 5a to 5d in a first and second switching position

7a, 7b and 7c each show a perspective side view of the coupling device from FIGS. 5a to 5d in a first, second or third switching position of the mode switch

8 shows a process diagram of the method according to the invention for operating a machine tool according to the invention

Description of the embodiments

1 shows a hammer drill 10 as an example of a machine tool according to the invention, in particular a power-operated hand tool according to the invention, in a schematic external view. The hammer drill has a tool holder 16 for receiving an insert tool 17 at a front end region of a housing 12.

On an upper surface of the housing 12, a mode switching element 13 configured as a mode switch 13a is disposed. The mode switch 13a is used to switch the hammer drill between at least two different

Modes. The hammer drill known from DE 10 2004 055 736 A1 has, for example, three operating modes, with two activating a rotary drive of the insertion tool 17. For this purpose, the hammer drill 10 is not shown here

Operating mode switching device 15 on. An operating mode switching device 15 is known, for example, from DE 10 2004 055 736 A1, to the description of which reference is made at this point.

In the housing 12 of the hammer drill 10 is a drive device 14 for rotating and / or beating drive of a not shown here, in a frontally mounted on the housing 12 tool holder 16 insert tool 17 and the

Operating mode switching device 15 is provided. The mode switching means 15 may be operated by an operator via the mode switching member 13, 13a operatively attached to the housing 12 for selecting a mode of operation. The Drive device 14 has an electric motor 18 as a drive unit 19, a transmission device 20 and a tool drive shaft 23 designed as a hammer tube 22. On one of the drive unit 19 facing away from end portion 22a of the hammer tube 22 of the tool holder 16 is arranged and non-rotatably, preferably releasably, in particular changably connected to the end portion 22a of the hammer tube 22. The hammer tube 22 is rotatably received in the housing 12 stored. In the embodiment of FIG. 2, the hammer tube 22 is received in a formed as a transmission carrier 24 inner housing 25 and rotatably supported. The inner housing 25 is in turn housed in the housing 12 fixed to the housing. The electric motor 18 has, according to FIG. 2, a motor shaft 26, at whose free end 27 an output pinion 28 is provided. The motor shaft 26 is arranged in the present embodiment at an angle, in particular at right angles to a main axis 30 of the hammer tube 22. The geometric arrangement of the motor shaft 26 is not essential to the invention. On the contrary, a machine tool according to the invention can also have arrangements of the motor shaft 26 oriented parallel to the tool drive shaft 23.

The output pinion 28 is operatively connected to the hammer tube 22 via the transmission device 20 such that the hammer tube 22 is rotationally driven by a rotational movement of the output pinion 28. 2, the transmission device 20 comprises a first gear stage 32. The first gear stage 32 is formed on an input side 32a by the output pinion 28 and on an output side 32b by a first spur gear 34 which meshes with the output pinion 28 , The first spur gear 34 is arranged on a parallel to the motor shaft 26 arranged transmission shaft 36 and preferably rotatably connected thereto. The transmission shaft 36 is rotatably supported in the gear carrier 24. On the transmission shaft 36, a second spur gear 38 is provided, which is preferably non-rotatably connected to the transmission shaft 36. The second spur gear 38 is part of a second gear stage 40, wherein the second spur gear 38 acts as an input side 40a of the second gear stage 40. The second spur gear 38 meshes with a clutch drive gear 42 of a clutch device 44 designed as a spur gear. The clutch drive gear 42 thus forms an output side 40b of the second gear stage 40.

The coupling device 44 is designed as a lock-up clutch, in particular as an at least two-stage lockup clutch 45. As will be described in more detail below, the coupling device 44, 45 is designed as an adjustable coupling device 44, 45. The Kupplungsungsantriebsrad 42 is disposed on a parallel to the transmission shaft 36 arranged clutch shaft 46 and freely rotatably mounted on this. The Kupplungsantriebsrad 42 is formed as a hollow disc rim 48 in which a Clutch mechanism 50 of the coupling device 44, 45 is arranged. The coupling mechanism 50 in the present example comprises two coupling means 51a, 51b, as will be described below.

The coupling device 44, 45 comprises a driven wheel 54 designed as a bevel gear 52, which is arranged on the coupling shaft 46. In a closed state of the coupling device 44, 45, the clutch drive gear 42 is operatively connected to the output gear 52, 54 such that rotational movement of the clutch input gear 42 is transmitted to the output gear 52, 54.

At the hammer tube 22, a shift sleeve 56 is arranged in the present embodiment. The shift sleeve 56 is rotatably and axially displaceably connected to the hammer tube 22. On an outer lateral surface 58 of the shift sleeve 56, a bevel gear 60 is arranged and preferably non-rotatably connected to the shift sleeve 56. The shift sleeve 56 has a first shift position with respect to an axial displacement V and at least one further, second shift position. In the first shift position, the shift sleeve 56 is positioned axially such that the bevel gear 60 is engaged with the bevel gear 52 of the clutch device 44, 45, so that rotational movement of the bevel gear 52 is transmitted to the bevel gear 60. As a result, a rotary drive of the hammer tube 22 is effected. This switching position is shown in Fig. 2. In the second switching position, not shown, the shift sleeve 56 is positioned axially such that the bevel gear 60 with the bevel gear 52 of the coupling device 44, 45 is disengaged, whereby the rotary drive of the hammer tube 22 is deactivated.

If the shift sleeve 56 is in the first shift position, the arrangement described above can transmit a rotational movement of the motor shaft 26 to the hammer tube 22 and thus to the tool holder 16 and the insert tool received therein, not shown here. In addition, the transmission device 20 of the hammer drill 10 of the

Embodiment, a percussion drive 62 as an output unit 62a for driving a striking mechanism 64. In the embodiment shown here, the percussion drive 62 is designed as an eccentric 66. In the present example, the first spur gear 34 has an eccentric pin 68 arranged at a radial distance from the transmission shaft 36. The first spur gear 34 thus acts as an eccentric 70. About a connecting rod 72 or a

Crank 73 is a percussion piston 74 of the running as a pneumatic cushion impact mechanism 64 operatively connected to the eccentric pin 68 and driven by this.

However, embodiments of the eccentric drive 66 are also possible, in which a separate eccentric wheel 70 is provided, which is optionally also arranged on the transmission shaft 36 or driven by at least one further gear stage. It is also possible instead of the eccentric 70, an eccentric shaft or use crankshaft. In addition, the type of percussion drive 62 is not essential to the invention, so that other, known to those skilled percussion drives such as wobble-drive, coaxial, Kipphebel- or push rod drives can be used in a machine tool according to the invention. The percussion piston 74 is arranged axially displaceable in a rear end region 76 of the hammer tube 22. Towards the tool holder 16, an air cushion 78 and a racket 80, which is likewise axially displaceable in the hammer tube 22, are provided in front of the percussion piston 74. In the present example, the hammer drill 10 further comprises an axially displaceable in the hammer tube 22 in front of the racket 80 arranged intermediate header 82.

If the percussion piston 74 is driven by the percussion drive 62 to an oscillating axial movement in the hammer tube 22, the racket 80, which is driven in the known manner by the air cushion 78 as an air spring, transmits impact impulses to the intermediate header 82, which in turn transmit the impact pulses to an insertion end 83 of an insert tool can. Since neither the exact structure nor the associated precise mode of action of the impact mechanism 64 are essential to the invention, the person skilled in the art will be referred to the relevant literature at this point.

About the operating mode switching device 15 of the hammer drill 10 according to the invention thus executed can be switched in particular selectively between the modes chiseling, impact drilling and drilling. These modes correspond to a pure oscillating axial drive, a combined axial-rotation drive or a pure rotary drive of the insert tool 17th

3, the area of the coupling device 44, 45 of the hammer drill 10 from FIG. 2 is shown enlarged as an example of a machine tool according to the invention. The clutch mechanism 50 of the clutch device 44, 45 has a first and a second clutch disc 84, 85, which are accommodated along the clutch shaft 46 lying one above the other in the disc rim 48. The disk rim 48 has on an inner circumferential surface 86 latching depressions 88, as they are best seen in Fig. 4a or Fig. 4b. The locking recesses 88 have a directed in the circumferential direction locking profile 89 and extend parallel to the coupling shaft 46 in the axial direction.

In a preferred embodiment, the detent recesses 88 and the detent profile 89 are arranged on a radial inner surface of a recess carrier. The recess carrier is received in the clutch drive gear 42.

FIGS. 4a and 4b show two different embodiments, which differ in the design of the locking profile 89 and the number of locking recesses 88. To the number of locking recesses 88 are corresponding in the clutch plates 84, 85th provided to the outer diameter open radial grooves 90. In the inner radial region toward a central bores, the radial grooves 90 are closed by an inner retaining ring 91. In each radial groove 90 designed as a coil springs spring element 92 and, in the direction of the outer diameter to be arranged locking element 94 is added. Preferably, the locking element 94 is a cylinder pin or

Ball executed. The spring element 92 is biased such that the detent element 94 is pressed with a defined detent force FR against the inner circumferential surface 86 of the disk rim 48, in particular into the detent recess 88.

The number of locking recesses 88 and of corresponding radial grooves 90 can be chosen freely. In particular, it is also possible that the number of

Locking depressions 88 and the number of radial grooves 90 differ from each other. Preferably, however, a radially symmetrical arrangement of locking recesses 88 and radial grooves 90 is selected over the circumference. Due to the radial symmetry as uniform as possible loading of the clutch mechanism 50 is achieved. The embodiments shown in FIGS. 4a and 4b have eight or four locking depressions 88 and radial grooves 90 distributed uniformly over the circumference.

In a preferred embodiment, in particular the latching profiles 89, 89a, 89b and / or the elastic latching elements 93, 93a, 93b may be designed differently for each coupling means 51a, 51b. In the clutch shaft 46 is an axially displaceable spool 96 a

Torque selector 97 arranged. To this end, the coupling shaft 46 is designed as a hollow tube 98 which is open at one end and at whose preferably closed end 100 the bevel gear 52 of the coupling device 44, 45 is arranged, preferably formed. The hollow tube 98 is rotatably supported by bearings in the gear carrier 24. The spool 96 has at least two radially outwardly facing control vanes 102. These control vanes 102 project with a free end 104 through corresponding control grooves 106, which are provided in the hollow tube 98. The inner retaining rings 91, 91 a of the clutch discs 84, 85 have on their outer surface of their inner diameter a number of receiving grooves 108, 109 for receiving the free ends 104 of the control vanes 102. The number of receiving grooves 108, 109 is at least equal to the number of control vanes 102 of the spool 96. The free ends 104 of the control vanes 102 can by axial displacement of the spool 96 selectively with the receiving grooves 108, 109 of the two clutch plates 84, 85 in engagement to be brought. In this case, the spool 96 is in a first axial control position SP1 when the control vanes 102 with the receiving grooves 108 of the first clutch disc 84 are engaged. In a second axial control position SP2, the control vanes 102 engage with the receiving grooves 109 of the second clutch disc 85.

In a preferred embodiment, the free ends 104 of the control vanes 102 in an axial intermediate position of the spool 96 can also be brought into engagement simultaneously with the receiving grooves 108, 109 of the two clutch discs 84, 85. By the engagement of the free ends 104 of the control vanes 102 in the receiving grooves 108, 109, the respective associated clutch disc 84, 85 rotatably connected to the hollow tube 98 and thus the coupling shaft 46.

In addition, for the sake of simplicity, only the variant without axial intermediate position of the spool 96 will be considered. As already indicated above are the

Latching elements 94 pressed by the prestressed spring elements 92 with the latching force FR in the locking recesses 88 of the pulley 48. As a result, a limit torque MG proportional to the latching force is established between the disk rim 48 and the hollow pipe 98 connected in a rotationally fixed manner via the control slide 96 to the respective clutch disk 84, 85.

The effective limit torque MG depends essentially on the value of the latching force FR, the number of pairs of radial grooves 90 and locking recesses 88 of the clutch disc 84, 85 and the geometric shape of the locking recesses 88 and / or the locking elements 94. By appropriate selection of these parameters, a first effective limit torque MG1 can be provided for the first clutch disc 84, which deviates from an effective second limit torque MG2 of the second clutch disc 85. In this case, the first limit torque MG1 is preferably smaller than the second limit torque MG2. If the first limit torque MG1 is the lowest limit torque MG that can be set with the clutch device 44, 45, it is also possible to speak of the lowest possible limit torque MGmin.

In the coupling device 44, 45 of the hammer drill 10 according to the invention of FIG. 3, the spool 96 is shown in the second control position, so that the second limit torque MG2 in the illustrated state of the hammer drill 10 is effective. At a control wing end 1 10 of the spool is an elastic

Return element 112 is arranged, wherein the elastic return element 1 12 is supported on an inner bearing surface 1 14 in the direction of the preferably closed end 100 of the hollow tube 98.

At an opposite, free end 1 16 of the spool 96, an actuator 118 is provided. The actuator 118 has a first one Switching state and at least one other switching state. The actuating device 118 comprises a latching device 120 with a latching position which makes the at least one further switching state releasably lockable. The latching device 120 has a triggering device 122 which makes a locked state of the latching device 120 releasable in an unlocking position. The triggering device 122 can be understood as an example of a means 122 'for resetting the coupling device 44, 45 to a lower, preferably the lowest possible limit torque. Furthermore, the actuator 1 18 a, preferably accessible to the housing 12, switching unit 124 for actuating the actuator 1 18 by an operator. In the first embodiment according to FIGS. 2 and 3, the actuating device 1 18 is designed as a mechanical actuating device 118a. The actuator 118a is an example of a mechanical means according to the gist of the present invention.

The switching unit 124 in this case has a switching element 126 which is arranged accessible to the operator 12 on the housing. In the present example, the switching element 126 is designed as a shift lever 128 which is movably received in the housing 12 and projects with one end 128 a partially out of the housing 12. The shift lever 128 is designed pivotable about a pivot axis 130. The pivot axis 130 is preferably carried out substantially perpendicular to the coupling shaft 46 of the coupling device 44, 45. At another end 128b of the housing 12

Shift lever 128, a rocker arm 132 is provided. One end 132 a of the rocker arm 132 protrudes into a receptacle 134 at the end 128 a of the shift lever 128. A second end 132 b of the rocker arm 132 has a fastening element 136. With the fastener 136 of the rocker arm 132 is connected to the free end 116 of the spool 96, preferably releasably connected. In the present exemplary embodiment according to FIGS. 2 and 3, the free end 16 of the control slide 96 has a receiving groove 138. The fastening element 136 is designed as a fastening fork 140, which engages in the receiving groove 138. The rocker arm 132 is pivotable about a rocker shaft 141, which is aligned substantially perpendicular to the coupling shaft 46 of the coupling device 44, 45.

The locking device 120 of the actuating device 118a is designed as a locking device 120a. The locking device 120a has for this purpose a locking lever 142, a locking lever pivot axis 144 and a closing element 145. The locking lever 142 is designed as an angle lever 146. A first end 146 a of the angle lever 146 is angled at a distance from rocker shaft 141 at an angle, preferably at right angles to a first, preferably to the coupling shaft 46 parallel lever arm 147 a in the direction of the spool 96. At the first end 146a of the bell crank 146 is a Detent element 148 is provided, preferably formed. The latching element 148 is a latching profile 150 parallel to the coupling shaft 46. On a side facing away from the coupling device 44, 45 side 150a, the latching profile 150 is wedge-shaped to the first end 146a down sloping. On the opposite, the coupling device 44, 45 facing side 150 b latching profile 150 is designed substantially flat.

Between the coupling shaft 46 preferably parallel extending part of the first lever arm 147a and a relative to the locking lever 142 fixed contact surface, the closing element 145 is arranged. In the embodiment shown here, the closing element 145 is designed as a helical spring. The closing element 145 is designed and arranged such that the locking lever 142 is returned to a preferred rest position. Fig. 3 shows the locking lever 142 in this rest position.

In this rest position, the latching element 148 covers at the first end 146a of the locking lever 146 a pivoting area 152 of the second end 132b of the rocker arm 132 so that a pivotal movement of the rocker arm 132 substantially only in a first, coming from the direction of the side 150a of Einrastprofils 150 pivoting direction R1 is possible.

If the second end 132b of the rocker arm 132 passes over the latching element 148 during a pivoting movement from the pivoting direction R1, then the locking lever 142 is momentarily deflected against a closing force FS of the closing element 145. If the pivoting movement continues in the pivoting direction R1, the closing element 145 returns the locking lever 142 to its rest position. During a movement in the pivoting direction R1, the control slide 96 is also displaced against the force of the restoring element 112 into the second axial control position SP2. A pivoting movement of the rocker arm 142 in a second, coming from the direction of the side 150b of the latching profile 150 pivot direction R2 is largely blocked by the substantially planar design of the Einrastprofils 150 on the side 150b of the locking element 148. This avoids spontaneous return of the spool 96 from the second control position SP2 selected by the operator to the control position SP1. Preferably, a blocking action of the latching device 120 is designed so that a triggering of the latching device 120 is possible by manually operating the switching element 126, so that the operator can switch back to the control position SP1 and thus to the first limit torque MG1.

On a first lever arm 147a substantially opposite side of the Arretierhebelschwenkachse 144 is further provided a second, preferably rectilinearly executed lever arm 147b. This is largely freely movable during a movement in the first pivoting direction R1. Facing away from the coupling shaft 46

Side of the second lever arm 147 b, a control rod 154 is arranged as a mechanical element 155 of the triggering device 122. The triggering device 122 comprises, in addition to the control rod 154, a restoring element 156 which, in the present exemplary embodiment according to FIGS. 2 and 3, is supported on the gear carrier 24. The control rod 154 is designed as an angled push rod. At a end 154a facing the tool holder 16, it protrudes with a receiving element 158 from the front end of the housing 12 facing the tool holder 16. A second end 154b of the control rod 154 is arranged on the side of the second lever arm 147b remote from the coupling shaft 46. preferably directly adjacent, in a particularly preferred manner touching the second lever arm 147b executed. In an angular transition region 160 of the control rod 154, a contact surface 162 is provided. Between this contact surface 162 and a further contact surface on the gear carrier 24, the return element 156 is provided. The restoring element 156 thereby generates a restoring force directed in the direction of the tool holder 16, which restrains the control rod 154 in an axial starting position.

The tool holder 16 comprises a first actuating element 164. The first actuating element 164 serves to unlock a factory locking of a tool holder of the tool holder 16 by the operator. After unlocking an insert tool can be removed or replaced. Such tool holder 16 are well known to those skilled in the art, so that a detailed description is omitted here. In the present embodiment, the first actuating element 164 is designed as an actuating sleeve 164a. To unlock the actuating sleeve 164a is moved by the operator in the direction of the machine tool so as to trigger the release.

In the machine tool according to the invention according to the first embodiment, the pickup element 158 is arranged so that a front-side contact surface 166 of the actuating sleeve 164 a upon actuation by the operator a pressure on the

Transducer element 158 exerts. By this pressure, the control rod 154 is displaced axially in the housing 12 in the direction of the coupling device 44, 45 against the restoring force of the return element 156. This axial displacement is transmitted via the second end 154b of the control rod 154 to the second lever arm 147b of the locking lever 146. As a result, the locking lever 146 against the closing force of the

Closing member 145 pivoted from its rest position, so that the pivoting portion 152 of the rocker arm 132 is released. Now the spool 96 is reset due to the restoring force of the return element 1 12 in the first axial control position SP1. This triggers an automatic reset to the lowest possible limit torque MGmin of the coupling device 44, 45 triggered by a tool removal and / or a tool change on the tool holder 16. In addition to the embodiment of a mechanical actuating device 1 18a described in the first exemplary embodiment, alternative mechanical devices for switching one-sided locking of at least two control positions SP1, SP2 of a control slide 96 are known to the person skilled in the art. In particular, deviating switching elements 126 such as rotary switches, rocker switches, slide switches and similar switches for manual operation of the coupling device 44, 45 can be used according to the invention. The transmission from the actuating device 118a to the control slide 96 can also be achieved in a different manner in a known manner, without any changes essential to the invention being necessary. Thus, instead of the rocker arm 132 shift rods, traction devices, such as cable or Bowden cables, or similar arrangements are used. Furthermore, deviating locking devices 120 and / or reset devices 122 may be provided. In addition, the transmission of the actuation of the first actuating element 164, for example as a lever, push or pull device can be solved differently, without interfering with the character of the invention. FIGS. 5a to 5d show an alternative embodiment of an at least two-stage

Coupling device 344, 345. The reference numerals of the same or equivalent features are increased by 300 in this case.

The Kupplungsungsantriebsrad 342 is designed in the present embodiment as a pulley rim 348, wherein an open side of the pulley rim 348 opposite to the previous embodiment, the output gear 352, 354 faces. The clutch shaft 346 is shown in this example as a solid shaft. In principle, in order to increase the rigidity, the coupling shaft 346 can also be designed as a hollow shaft. In disk rim 348 two coupling means 351 a, 351 b are added. Each of the coupling means 351 a, 351 b thereby comprises a clutch disc 384, 385. The clutch disc 384 of the first clutch means 351 a rotatably connected to the clutch shaft 346, while the clutch disc 385 of the second clutch means 351 b rotatably festleg bar mounted on the clutch shaft 346 is. This can be seen particularly well in FIGS. 5c and 5d.

The clutch discs 384, 385 each have at least one, preferably a plurality of connecting bushings 466a, 466b. In a preferred embodiment, an equal number of connecting bushings 466a, 466b are provided in each clutch disc 384, 385. The connecting bushings 466a, 466b are preferably distributed over the circumference, preferably at a uniform spacing over the circumference of the respective coupling disk 384, 385, at a radial distance from the coupling shaft 346. In particular, the connecting bushings 466a, 466b in each clutch disc are designed such that they are brought into overlap, preferably coincidence, by a relative rotational movement of the clutch discs 384, 385 relative to one another can be. On each clutch disc 384, 385 are arranged analogously to the coupling device known from the foregoing elastic locking elements 393a, 393b, which caulk against a locking profile 389 with locking recesses 388 in pulley 398 and on exceeding the latching force FR1, FR2 of the elastic locking elements 393a, 393b can override.

In at least one, preferably a plurality of the connecting bushings 466a, 466b, axially displaceable connecting pins 468 are arranged relative to the coupling shaft 346. On a side facing away from the disk rim 398 side, the connecting pins 468 are arranged on a control disk 470, preferably connected to this, in particular in one piece with this. The control disk 470 is also axially displaceable relative to the coupling shaft 346, in particular limited axially displaceable.

The control disk 470 has a collar 472 on a circumference. The yoke 472 is taken in a receiving ring 474 of a sliding element 476 and freely rotatably mounted. Sliding element 476 in the present example is designed as a slide 478 with two symmetrical side wings 480, as best seen in FIG. 5a. On the side wings 480 one, preferably two return elements 482 is arranged. In this case, the restoring elements 482 are designed as spring elements 484 in the present example. The restoring elements 482, 484 exert a force on the sliding element 476, 478 oriented away from the coupling device 344, 345.

By the action of the return elements 482, 484, the control disk 470 is brought into a first axial control position SP1, as shown in Fig. 5c. The connecting pins 468 dive into the connecting bushing 466a of the clutch disc 384 of the first coupling means 351a. To the connection bushings 466b of the clutch disc 385 of the second coupling means 351 b is in the first

Control position SP1 no contact, whereby no torque transfer between the Kupplungsungsantriebsrad 342 and the coupling shaft 346 via the second coupling means 351 b can take place. In the control position SP1 alone, the first coupling means 351 a transmits torque. If the torque transfer between the clutch drive gear 342 and the clutch shaft 346 exceeds the limit torque MG1 of the first clutch means 351a, the clutch device 344, 345 triggers and interrupts the torque transfer.

If the control disk 470 axially displaced against the force of the restoring elements 482, 484 in the direction of the coupling device 344, 345 in a second control position SP2, the connecting pins 468 penetrate into the connecting bushings 466b of the clutch disc 385 of the second coupling means 351 b and apply this of the Clutch disc 384 firmly. As a result of this rotation determination, both coupling means 351a, 351b now act to transmit torque between the clutch drive gear 342 and the clutch shaft 346. A torque flow is split between the two clutch means 351a, 351b such that a second, higher limit torque MG2 is active on the clutch device 344, 345 , The limit torque MG2 substantially corresponds to the sum of MG1 of the first clutch means 351a and the limit torque of the second clutch means 351b. The thus adjustable coupling device 344, 345 thus has two selectable limit torques MG1, MG2. It will be obvious to a person skilled in the art by analogous addition of further coupling means 351 x to extend the coupling device shown here by further selectable torque stages.

In Fig. 6a and 6b, the coupling device just presented 344, 345 is shown in a partial side view of a transmission device 320 of a rotary hammer 310 according to the invention. Above the gear device 320, a switching slide 486 of the mode switching device 315 of the hammer drill 310, which extends substantially transversely to the coupling shaft 346, is arranged. The switching slide 486 essentially connects the operating mode switching element 313, not shown here, with operating mode switching means provided in the transmission device 320. If an operating mode changeover is set via the operating mode switching element 313 (not shown here), then the switching slide 486 is displaced essentially along its longitudinal extent.

With regard to the embodiment mode switching means, for example, reference is made to the description in DE 10 2004 055 736 A1, since their execution have no influence essential to the invention.

The switching slide 486 has a switching profile 490 on a contact surface 488 facing the coupling device 344, 345, in particular the sliding element 476, 478. Preferably, the sliding element 476, 478, which is displaced by the return elements 482, 484 in the direction of the contact surface 488, is supported on the contact surface 488, in particular on the switching profile 490.

The shift profile 490 sets in a, a setting of a limit torque on the coupling device 344, 345 corresponding portion of the displacement of the slide 486 along its longitudinal extent in a substantially perpendicular axial movement of the sliding member 476, 478.

6a shows the control disk 470 in the control position SP1, while FIG. 6b shows the control disk 470 after a displacement V of the slide valve 486 in the control position SP2. FIGS. 7 a to 7 c show the described operating mode changeover on the hammer drill 310 in a perspective schematic representation of the gear mechanism 320 together with the mode switch 313.

FIG. 7 a shows the hammer drill 310 in a first operating mode, wherein the rotary drive of the tool drive shaft is interrupted by a coupling device 492, not described here in greater detail, on the tool drive shaft 323. In this operating mode, only impact mechanism 364 is activated, so that is also referred to as a "chiseling" mode of operation Since no rotational drive of insert tool 317 takes place in this operating mode, adjustment of adjustable coupling device 344, 345 is not necessary Sliding element 476, 478 is held here by the restoring elements 382, 384 in a position such that the control disk remains in the first control position SP1.

Fig. 7b shows the same hammer drill 310 in a second mode in which the coupling device 492 is closed, so that the tool drive shaft 323 is driven in rotation. In this mode of operation, either hammer mechanism 364 may be deactivated, so as to speak of a drilling mode, or be activated, so as to speak of a percussion drilling mode. In the second operating mode, the slide switch 386 is in an axial position, in which the shift profile 390 does not yet displace the slide element 476, 478 and thus the control disk 470 from the first control position SP1.

FIG. 7c shows the hammer drill 310 in a third operating mode, which corresponds with respect to a drive of the insert tool 317 to the operating mode from FIG. 7b. Deviating from the

Mode of operation of Fig. 7b, however, the shift slide 486 is shifted axially so far that the shift profile 490, the sliding member 476, 478 in the direction of the coupling device 344, 345 moves. As a result, the control disk 470 is transferred from the first control position SP1 to the second control position SP2. At the coupling device 344, 345 now both coupling means 351a, 351b act to transmit torque, so that the second limit torque MG2 is effective.

The embodiment set forth above describes a particularly compact embodiment of an actuation of the torque selection device 397 of the adjustable coupling device 344, 345 via the operating switching element 313 of a machine tool. The switching slide 486 with the switching profile 490 described here represents an example of a means of action according to the independent claim of the invention. In addition to the slide 486 shown here, other pressure, shear and / or tension elements can be used as active agents for a functional composite according to the invention, Also, electromechanical and / or electronic elements can be used as appropriate agents. Other modifications and developments will become apparent to those skilled in obvious from combinations of the features described above.

In addition to the examples of an adjustable coupling device described here, the person skilled in the art will be familiar with further embodiments of adjustable coupling devices having a torque selection device which can be connected to the operating mode switching element of the machine tool in the sense of the invention by suitable means of action.

In another aspect of the present invention, a method according to the invention for operating a machine tool is characterized by the method steps shown schematically in FIG. 8. In a first step S1, an operator of the machine tool sets a desired mode MOD_setpoint on a mode switching element 13, 13a provided on the machine tool. In this case, the machine tool has at least two operating modes, each of which corresponds to a different limit torque MG1, MG2 that can be set on the coupling device 44, 45. In a, preferably automatically executed step TS1 it is checked whether in the desired mode MOD_Soll the set limit torque of the coupling device 44, 45 changed, in particular to a value MG_Soll has to be changed. In a further, preferably automatically executed substep TS2, it is checked whether a limit torque MGJst, which corresponds to the limit torque MG_Soll of the selected operating mode MOD_Soll, is already set at the clutch device 44, 45. In a subsequent step S2, the torque selector 97 of the clutch device 44, 45 is set, in particular automatically adjusted so that the set limit torque MGJst the clutch device 44, 45 corresponds to the desired limit torque MG_Soll. In simplified embodiments, the method according to the invention may also comprise only steps S1 and S2 or S1, TS1 and S2.

In a further development, the method according to the invention comprises a secondary process, referred to as a provision, consisting of two substeps ZS1, ZS2. In this secondary process, a provision, in particular an automatic reset of the adjustable coupling device 44, 45 to a lower, in particular the lowest possible limit torque MGmin, when the insert tool 17 off and / or in the tool holder of the tool holder 16 by the operator and / or is introduced. For this purpose, an insertion and / or an execution of the insertion tool 17 in and / or out of the tool holder 16 is detected in the partial step ZS1. In the second partial step ZS2, the to be set on the coupling device 44, 45 Limit torque MG_Soll set to a lower, preferably the lowest possible limit torque MGmin and finally executed step S2.

In an additional development, the operating mode switching element 13, 13a is reset to the mode MOD_MGmin in a sub-step ZS3, in particular reset automatically, in which a lower, in particular the lowest possible limit torque MGmin is selected on the coupling device 44, 45.

Claims

claims

1. Machine tool, in particular an electrically operable hand tool, with at least one tool drive shaft (23, 323) for rotational drive of, in a tool holder of a tool holder (16, 316) exchangeably recorded insert tool (17, 317), in particular a drill, a percussion drill or a Rotary hammer, with at least one, a transmission device (20, 320) having drive device (14, 314), with one, a mode selector element (13, 13a, 313, 313a) having mode switching means (15, 315) for switching between different, on the machine tool operating modes and with at least one adjustable coupling device (44, 45, 344, 345) which couples at least one tool drive shaft (23, 323) to the at least one drive device (14, 314) and at least two different ones via a torque selector (97, 397) selectable limit torques, characterized gekennzei in that at least one active means (186, 486) is provided, with which the torque selection device (97, 397) is operatively connected to the operating mode switching device (15, 315), in particular the operating mode switching element (13, 13a, 313, 313a) such that the Torque selector (97, 397) via the mode selector element (13, 13a, 313, 313a) is operable.

2. Machine tool according to claim 1, characterized in that at least one of the different operating modes of the machine tool selectable

Limit torque of the adjustable coupling device (44, 45, 344, 345) via the mode switching element (13, 13a, 313, 313a) is adjustable.

3. Machine tool according to claim 1 or 2, characterized in that the transmission device (20, 320) of the machine tool comprises a driven unit (62a, 362a), which is provided for an oscillating axial drive of the insert tool, and that with the operating mode switching device between at least two modes , which consist of a pure axial drive, a combined axial-rotation drive and / or at least one pure rotary drive, can be switched.

4. Machine tool according to at least one of the preceding claims, characterized in that the transmission device (20, 320) as a two- or multi-speed transmission device (20, 320) for the rotary drive of the insert tool (17, 317) is executed, wherein the transmission device ( 20, 320) provides different, switchable gear ratios to a torque transfer between an input side and an output side of the transmission device, and that a first mode as a rotary drive of the insert tool in a first gear with a first gear ratio of the transmission device and the at least one other mode than a Rotary drive of the insert tool in a second gear with a second ratio of the transmission device (20, 320) are executed.

5. Machine tool according to claim 4, characterized in that the transmission device (20, 320) in the first gear, the maximum torque between the input side and the output side transmits, and that in the first mode via the mode switching element (13, 13a, 313, 313a) the selectable limit torque of the adjustable clutch device (44, 45, 344, 345) is adjustable via the mode selector element (13, 13a, 313, 313a).

6. Machine tool according to at least one of the preceding claims, characterized in that a first limit torque MG1 of the at least two limit torques of the adjustable coupling device (44, 45, 344, 345) is smaller than the at least one second limit torque MG2, in particular the lowest possible limit torque MGmin adjustable coupling device (44, 45, 344, 345) corresponds.

7. Machine tool according to at least one of the preceding claims, characterized in that the torque selection device (97, 397) has at least two switching positions, wherein a first switching position is provided, in which the first limit torque MG1, in particular the lowest possible limit torque MGmin of the adjustable coupling device (44 , 45, 344, 345).

8. Machine tool according to at least one of the preceding claims, characterized in that on the adjustable coupling device (44, 45, 344, 345), a reset device (122, 422) is provided, with the torque selector (97, 397) of the coupling device (44 , 45, 344, 345) of a, not the first switching position corresponding other switching position of the at least two switching positions in the first switching position is reset, in particular automatically reset when the insert tool (17, 317) from and / or in the tool holder of Tool holder (16, 316) off and / or imported.

9. A method for operating a machine tool with at least one, via a drive device (14, 314) driven tool drive shaft (23, 323) for the rotary drive of, in a tool holder of a tool holder (16, 316) exchangeable recorded insert tool (17, 317), with operating mode switching device (15, 315) having an operating mode switching element (13, 13a, 313, 313a) for switching between different operating modes provided on the machine tool and having at least one, the at least one tool drive shaft (23, 323) with the at least one drive device ( 14, 314) adjustable adjustable coupling device (44, 45, 344, 345) having at least two different, via a torque selector (97, 397) selectable limit torques, in particular according to one of the preceding claims, wherein the mode switching means (15, 315) at least one, in particular at least one additional Betriebsa rt for each selectable limit torque MG1, MG2 of the adjustable clutch device (44, 45, 344, 345), characterized in that for selecting a limit torque of the adjustable clutch device (44, 45, 344, 345) by an operator on

Mode switching element (13, 13a, 313, 313a) is set to the selected limit torque corresponding mode MOD_Soll.

10. The method according to claim 9, characterized in that tested in a substep TS1, in particular automatically checks whether in the selected mode MOD_Soll the torque selector (97, 397) of the coupling device (44, 45, 344, 345) to be adjusted.

1 1. A method according to claim 9 or 10, characterized in that checks in a substep TS2, in particular automatically checks whether at the coupling device (44, 45, 344, 345) already a limit torque MG_lst is set, the limit torque MG_Soll the selected mode MOD_Soll corresponds.

12. The method according to at least one of claims 9 to 11, characterized in that in a step S2, the torque selector (97, 397) of the coupling device (44, 45, 344, 345) is set, in particular automatically adjusted so that the set Limit torque MGJst the coupling device (44, 45, 344, 345) corresponds to the desired limit torque MG_Soll.

13. The method according to at least one of claims 9 to 12 characterized by a provision, in particular automatic return of the adjustable coupling device (44, 45, 344, 345) to a lower, in particular the lowest possible limit torque MGmin when the insert tool (17, 317) by the operator from and / or in the tool holder of the tool holder (16, 316) off and / or imported.

14. The method according to claim 13 characterized by a provision, in particular automatic return of the mode switching element (13, 13a, 313, 313a) in an operating mode corresponding to the lowest possible limit torque MGmin.