EP4353417A1 - Mobile machine tool with activatable or permanent inhibiting stage - Google Patents

Abstract

A mobile machine tool (1) is presented, having a multi-stage transmission (2), wherein a drive shaft (3) of the transmission (2) and an output shaft (6) of the transmission (2) are arranged concentrically to a main axis (8), wherein the transmission (2) has at least one reduction stage (4) which is arranged to reduce a speed of the drive shaft (3) to a speed of the output shaft (6), characterized in that the transmission (2) has at least one at least switchable inhibiting stage (5) which is arranged to inhibit a torque flow from the output shaft (6) to the drive shaft (3).

Description

FIELD OF INVENTION

The present invention relates to a mobile machine tool

For example, tool holders are common in drilling machines, grinding machines and sawing machines. These are based on turning an operating part of the tool holder relative to a spindle or output shaft of the machine tool in order to change a tool. A locking mechanism, also known as a spindle lock, is often provided to apply a counter torque.

The locking mechanism generally protects a drive, a drive-side gear stage and/or electronics from the effects of an externally applied torque or an externally applied rotary movement.

The locking mechanism is usually arranged kinematically close to the tool or the tool holder. It is therefore particularly exposed to vibrations and high torques. For this reason, it is subject to high levels of wear and tear and has a major influence on the kinematic feel of the machine tool.

The EP 0 444 790 A2 discloses an internal tooth type planetary gear speed change device made of plastic, comprising an input shaft formed integrally with an eccentric member; an external tooth gear fitted on the eccentric member; inner pins formed on and integrally with the external tooth gear; an internal tooth gear for meshing with the external tooth gear; an output shaft provided with a flange at one end thereof; and inner pin holes formed in the flange for inserting the inner pins; each inner pin having recesses on inner and outer sides thereof, the inner and outer sides extending opposite to each other and facing in a radial direction of the externally toothed gear, and wherein only the inner pins which serve to transmit a torque are arranged to contact with the inner pin holes at a predetermined range of a contact location.

The DE 24 33 675 discloses a planetary gear with at least one planetary gear moved by means of an eccentric and with at least one concentric sun gear, both of which wheels engage via a closed cam cycloid formed on one wheel and a roller ring formed on the other wheel, the points of contact of which with the cam cycloid describe points of a reference cycloid.

The EP 0 761 350 A1 discloses a locking device for locking an output shaft of a machine tool which is rotatably coupled to a drive shaft so that play between the shafts is possible. The device comprises an annular locking ring which carries pawls, the ring being movable between a concentric and an eccentric position relative to the output shaft. The device further comprises an operative connection means which presses the locking ring into the eccentric position in which the pawl operatively connects with a means whereby rotation about the output shaft is substantially prevented when the drive shaft is not driven and the play between the shafts is eliminated.

The EN 10 2014 222 253 A1 discloses a handheld power tool device with at least one gear unit that has a drive element that is intended for a pure rotary movement, that has an output element that is intended for a pure rotary movement, and that is intended for a speed and/or torque conversion between the drive element and the output element, wherein the gear unit has an eccentric element that is intended to translate a pure rotary movement of the drive element into an eccentric movement to drive the output element in at least one operating state. The gear unit is designed in particular as a cycloidal gear.

Against this background, an object of the present invention is to provide a mobile machine tool with reduced wear.

DISCLOSURE OF THE INVENTION

Accordingly, a mobile machine tool is proposed which has a single-stage or multi-stage transmission. The transmission contains a drive shaft and an output shaft. The drive shaft and the output shaft are arranged concentrically to a main axis. Furthermore, the transmission has at least one reduction stage which is designed to reduce a speed of the drive shaft to a speed of the output shaft. In addition, the transmission has at least one at least switchable inhibiting stage which is arranged to inhibit a torque transmission or a torque flow from the output shaft to the drive shaft. The inhibiting stage means that the locking mechanism can be omitted. Consequently, no locking mechanism can wear out, and therefore wear on the machine tool is reduced.

The "at least switchable" inhibiting stage can in particular be and/or contain a switchable inhibiting stage and/or an inhibiting stage permanently connected between the drive shaft and the output shaft.

A "stage" is understood to mean a gear stage. A stage can be characterized in particular by a function, such as a reduction or increase in speed, a dampening, a spring, a dampening, a change in the temporal progression of a speed and/or a torque, a conversion of a movement, a blocking of a movement, in particular a blocking of a torque transmission, and/or a combination thereof. Several stages can use parts in common. A stage can often be recognized by its own section of a force flow or torque flow.

The reduction stage has the effect that in an operating state a speed of the output shaft is lower than a speed of the input shaft and preferably a torque in the output shaft is greater than a torque in the input shaft. For example, The input shaft and the output shaft can be distinguished by a reduction ratio of the reduction shaft.

The drive shaft can be, for example, part of a drive device, such as an electric motor, in particular a DC motor, for example a rotor. The drive shaft can be, for example, part of a drive-side stage of the transmission.

The output shaft can be, for example, a spindle and/or part of a spindle. The output shaft can be, for example, rotationally coupled to a spindle. The output shaft can be, for example, part of a tool interface, in particular a tool holder, and/or coupled thereto. The output shaft can be, for example, part of an output-side stage of the transmission. The output shaft can in particular be part of the inhibiting stage and/or connected thereto and/or connectable thereto in a switching manner.

The reduction stage and the inhibiting stage are preferably connected in series. This ensures the reliability of the inhibiting.

In order to improve the protective function of the inhibiting stage, the inhibiting stage is preferably provided as close to the output side as possible in the machine tool, in particular in the gearbox.

For example, the braking stage is preferably arranged on the output side of the reduction stage. This has the additional benefit that the reduction stage can be used to increase torque in order to overcome friction or the like within the braking stage.

The stages of the gear preferably each have a drive-side member and an output-side member, which are concentric to the main axis. In combination with the concentric drive shaft and the concentric output shaft, an overall concentric gear is obtained. This can be advantageous, for example, for balancing hand-held machine tools.

According to a preferred embodiment, the inhibiting stage contains a cycloidal gear stage and/or a stress wave gear stage. Typically, the inhibiting stage contains only one of the two mentioned gear stages in order to save weight. The reduction stage preferably contains a planetary gear stage, a cycloidal gear stage and/or a stress wave gear stage. Both similar and different types of gear stages can - depending on the specific case - be advantageous for high reduction ratios.

A preferred design of a cycloidal gear or a cycloidal gear stage is briefly discussed, which is merely an example. On the drive side there is a shaft on which an eccentric or an eccentricity is formed. A cycloidal disk or cam disk is rotatably mounted on the eccentric, for example with a roller bearing or plain bearing in between. The cycloidal disk has an external toothing which meshes with an internal toothing of a ring gear arranged radially on the outside. The term "toothing" in this case is an umbrella term for a pair of oppositely identical, periodically alternately projecting and recessed contours. Various toothings are possible, with low-friction rolling toothings being advantageous. The internal toothing is concentric to the shaft, and at the same time the toothing and the eccentric are dimensioned such that the toothing meshes in the extension of the eccentric and they do not engage radially on the side facing away from the eccentric. A rotation of the shaft causes a rotation of the eccentric, which in turn causes the external gearing to mesh with the internal gearing. The cycloid disk usually forms a positive connection in the circumferential direction with an output disk and/or shaft. The positive connection usually enables an eccentric movement of the cycloid disk to be compensated in the radial direction. A rotational movement of the cycloid disk around the eccentricity is thus transferred into a rotational movement of the output disk and/or shaft.

The term "toothing" can, for example, refer to an active surface or active surface arrangement on a component or assembly. For example, a "toothing" can be a peripheral section of a gear. The term "toothing" can, for example, a geometric and/or mechanical interaction of at least two such active surfaces or active surface arrangements. For example, a "toothing" can refer to the meshing of two gears.

A strain wave gear is also known by the terms "harmonic drive", "wave gear", "sliding wedge gear" or "strain wave gear". A preferred structure of a strain wave gear or a strain wave gear stage is briefly described, which is merely an example. On the drive side there is an elliptical disk. This rotatably supports a sleeve that is flexible, flexible and/or at least not rigid and parallel to the main axis. A flexible, flexible, at least not rigid and/or deformable bearing, such as an adapted roller bearing and/or plain bearing, is preferably connected between the elliptical disk and the sleeve. The sleeve has an external toothing that meshes with the internal toothing of a ring gear. Here too, the term "toothing" is to be interpreted broadly. The difference in length between a main axis and a minor axis of the ellipse and the gearing are dimensioned such that the gearing meshes in the extension of the main axis and the gearing in the extension of the minor axis does not mesh. A rotation of the elliptical disk causes the external gearing to mesh with the internal gearing. An output disk forms a positive connection with the sleeve in the circumferential direction and compensates for the difference in length in the radial direction. A rotation of the sleeve is thus transferred to the output disk.

The above descriptions are for informational purposes only and contain only preferred, partly optional features.

If the cycloidal gear stage has at least two cycloid disks or cam disks that are symmetrically phase-shifted to one another in the direction of rotation, an imbalance can be compensated for, for example. This can improve smooth running, for example. "Symmetrically phase-shifted" is an angle equal to 360°/n, where n is the number of cycloid disks in the stage or cycloid disks connected in parallel.

To facilitate assembly, the respective eccentrics or eccentric disks, which each eccentrically mount at least one of the at least two cycloid disks, have eccentric diameters that increase in an assembly direction. This means that, for example, the cycloid disk to be assembled first can easily be assembled over the eccentric for the other cycloid disk.

In an embodiment preferred for reasons of efficiency, the reduction ratio of the reduction stage can be from 1:2 to 1:20 and preferably from 1:5 to 1:15.

In addition to the ability to switch on the braking stage, the gear unit preferably has a variable gear ratio, with the reduction stage in particular being switchable. By means of the variability or switching, a user can use different tools to suit the situation. This enables a wide range of applications for the proposed machine tool.

The machine tool is preferably provided with a tool interface which is designed for at least temporarily attaching a tool. The tool interface is preferably rotationally coupled to the output shaft so that the inhibition of the inhibiting stage acts directly on the tool interface. The tool interface is preferably designed as a tool holder.

The mobile machine tool can be a hand-held machine tool, for example a drilling machine, a screwing machine, a chiseling machine, a grinding machine, a sawing machine or the like. It is also conceivable that the mobile machine tool is a construction robot or comprises a construction robot. The mobile machine tool can have a manipulator, in particular a multi-axis manipulator. The mobile machine tool can have a drive device for driving a tool, for example a drill, a chisel, a vacuum cleaner or the like.

The mobile machine tool can be designed to work on concrete and/or metal. It can be designed for drilling, chiseling, sawing and/or grinding.

In general, the mobile machine tool can be set up to carry out work in building and/or civil engineering. It is conceivable that it is not set up for use in mining.

The mobile machine tool may be portable; for example, it may have a weight of less than 50 kg, in particular less than 25 kg.

Further possible implementations of the invention also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the embodiments of the invention described below. The invention is explained in more detail below using preferred embodiments with reference to the attached figures.

SHORT DESCRIPTION OF THE CHARACTERS

Fig.1

shows a schematic longitudinal section through a transmission of a mobile machine tool according to a first embodiment of the invention;

Fig.2

shows a schematic perspective exploded view of the transmission according to the first embodiment;

Fig.3

shows a schematic plan view in the axial direction of the transmission and a reduction stage thereof according to the first embodiment;

Fig.4

shows a schematic perspective exploded view of the reduction stage according to the first embodiment on a larger scale than the Fig.2 ;

Fig.5

shows a schematic perspective exploded view of a switchable braking stage of the transmission according to the first embodiment on a larger scale than the Fig.2 ;

Fig.6

shows a schematic longitudinal section through a transmission of a mobile machine tool according to a second embodiment of the invention;

Fig.7

shows a schematic perspective exploded view of the transmission according to the second embodiment;

Fig.8

shows a schematic perspective exploded view of selected parts of the transmission, in particular a reduction stage and a braking stage, according to the second embodiment on a larger scale than the Fig.7 ; and

Fig.9

shows a schematic perspective exploded view of selected parts of the transmission, in particular a housing with shift levers, according to the second embodiment, also on a larger scale than the Fig.7 .

In the figures, identical or functionally equivalent elements have been given the same reference numerals unless otherwise stated.

A mobile machine tool 1 according to a first embodiment is described with reference to Fig. 1 to 5 described. The machine tool 1 is, for example, a portable drilling and screwing machine with a weight of up to 15 kg.

The machine tool 1 has a gearbox 2. The gearbox 2 has an input shaft 3, a reduction stage 4, an inhibiting stage 5 and an output shaft 6. The reduction stage 4 and the inhibiting stage 5 are collectively referred to as gear stages 4, 5.

The transmission 2 has a transmission housing 7, which, for example, supports the output shaft 6 radially and/or axially. In addition, the transmission housing 7 houses, for example, the gear stages 4, 5 and at least in sections the shafts 3, 6.

The transmission 2 has a main axis 8. The drive shaft 3 and the output shaft 6 are arranged concentrically to the main axis 8.

Furthermore, the transmission 2 has a circuit 9 which is designed to selectively switch the braking stage 5 on and off.

The drive shaft 3 is, for example, part of a rotor (not shown) of an electric motor (not shown), in particular of the brushless DC motor type.

In the following, the reduction stage 4 is described, with particular reference to the Fig. 3 and 4 is referred to.

The reduction stage 4 has two eccentrics 10 which are formed in one piece with the drive shaft 3. The eccentrics 10 each have a cylindrical circumference around a respective eccentric axis 11. The eccentric axes 11 are parallel to the main axis 8 and offset in the opposite direction by the same distance from the main axis 8.

Each eccentric 10 radially supports a cycloid disk 12. The respective cycloid disk 12 is rotatable about the eccentric 10. An optional bearing device radially interposed between the respective eccentric 10 and the corresponding cycloid disk 12 is not shown.

As from the Fig.4 As can be seen, the eccentrics 10 each have a different circumference. The diameter of the eccentric 10 located axially inside the drive shaft 4, which is in the Fig.4 right, is in this case at least twice the distance between the two eccentric axes 11 larger than the diameter of the eccentric 10 located axially outside along the drive shaft 4, which is in the Fig.4 This allows, for example, without tilting or scratching, and therefore without assembly-related Wear, the respective cycloid disk 12 must be mounted on the corresponding eccentric 10.

A roller bearing ring 14 supporting several rollers 13 is arranged radially outside the cycloid disks 12. The roller bearing ring 14 is mounted, for example, in the gear housing 7. The roller bearing ring 14 holds each roller 13 in the radial direction and in the circumferential direction to the main axis 8. Preferably, each roller 13 can rotate in the roller bearing ring 14 about its longitudinal axis in order to reduce friction of the reduction stage 4.

A respective external toothing 15 is provided radially on the outside of the cycloid disks 12. The external toothing 15 meshes with the rollers 13 in a section in extension of an eccentricity of the respective eccentric 10. The external toothing 15 is not in engagement with the rollers 13 in a section which faces away from the eccentricity.

In the cycloid disks 12, driving contours 17 are formed as through-holes. The driving contours 17 extend in the axial direction. A driver 18 engages in each of the driving contours 17 with compensating play. The drivers 18 are designed as axially projecting pins on a disk 19.

In the case of the first embodiment, thirteen rollers 13 are provided and the external toothing 15 has twelve radially projecting rounded cams 16. This results in a reduction ratio of the reduction stage 4 of 12:1. This means that twelve revolutions of the drive shaft 3 cause one revolution of the disk 19. Furthermore, a torque in the drive shaft 4 is amplified to a first approximation to twelve times the torque in the disk 19. Due to losses, a real torque in the disk is usually less than the calculated torque.

The components drive shaft 3, eccentric 10, cycloid disks 12 with driving contours 17 and external teeth 15 with cams 16, roller bearing ring 14 with rollers 13, and Disc 19 with drivers 18 act together as a cycloidal gear stage 20, which forms the reduction stage 4.

The following describes the inhibition stage 5. The inhibition stage 5 is designed as a further cycloid gear stage 21.

The cycloid gear stage 21 also has two eccentrics 22 which are formed integrally with the disk 19.

The eccentrics 22 each support a cycloid disk 23. Each cycloid disk 23 has an external toothing 24 with rounded cams 25. The cams 25 mesh in sections with rollers 26, which are supported by a roller bearing ring 27. Each cycloid disk 23 has driving contours 28, into which drivers 29 engage, which protrude axially from a disk 30 and are formed in one piece with it.

The disk 30 has a polygonal contour 31 radially on the inside, which matches a polygonal contour 32 on the outside of the output shaft 6. The polygonal contours 31, 32 are a shaft-hub connection, via which a speed and a torque can be transmitted between the disk 30 and the output shaft 6.

In the cycloidal gear stage 21, the eccentric axes 33 of the eccentrics 22 are also arranged at the same distance parallel to the main axis 8 and offset by a phase of 180°.

The cycloidal gear stage 21 has seven rollers 26 and twelve cams 25 per cycloidal disk 23, resulting in a reduction ratio of 12:5, i.e. 2.4:1. In other words, 2.4 revolutions of the drive-side disk 19 cause one revolution of the output-side disk 30 of the cycloidal gear stage 21. Accordingly, a torque in the drive-side disk 19 is amplified to up to 2.4 times the torque in the output-side disk 30.

For further information on cycloidal gear stage 21, please refer to the description of cycloidal gear stage 20.

Cycloidal gears have a self-locking behavior: a torque from the respective output side, here the disks 19 and 30, does not lead to a rotation of the respective eccentrics about the respective main axis. Therefore, the cycloidal gear stage 21 as the inhibiting stage 5 inhibits a torque transmission from the output shaft 6 to the drive shaft 3.

In the following, circuit 9 is described in particular with reference to the Fig.5 , 2 , 1 described.

The roller bearing ring 27 of the cycloidal gear 21 of the braking stage 5 has an external toothing 34 on the radial outside. A shift sleeve 35 is mounted axially displaceably on the external toothing 34, which has an internal toothing 36 on the radial inside that is the same as the external toothing 34. The disk 19, which is a drive-side member or input member of the cycloidal gear stage 21, also has an external toothing 37 on the radial outside. The external toothings 34, 37 are identical to one another and they each form a clearance fit with the internal toothing 36.

The shift sleeve 35 has an external toothing 38, and the gearbox housing has a matching internal toothing 39.

In a first switching position of the shift sleeve 35, which is in the Fig.1 As shown in section, the internal toothing 36 simultaneously engages both external toothings 34, 37. Thus, the disk 19 is short-circuited with the roller bearing ring 27. The inhibiting stage 5 is thus switched off. In the first switching position, the external toothing does not engage the internal toothing 39. Thus, the cycloidal gear stage 21 can be rotated as a package around the main axis 8.

In a second switching position of the shift sleeve 35, the internal toothing 36 of the shift sleeve 35 does not engage with the external toothing 37 of the disk 19, but with the external toothing 34 of the roller bearing ring 27. The disk 19 is thus rotatable relative to the roller bearing ring 27. In addition, the external toothing 38 of the shift sleeve 35 engages in the second switching position of the shift sleeve 35 with the internal toothing 39 of the Gear housing 7. The roller bearing ring 27 is thus fixed to the gear housing 7. A rotation of the disk 19 is therefore reduced to a rotation of the disk 30. If the shift sleeve 35 is in the second switching position, the inhibiting stage 5 is therefore switched on.

The shift sleeve 35 can be selectively moved between the first shift position and the second shift position.

For this purpose, the switching sleeve 35 has, for example, a radially outer circumferential groove 40 into which a switching bracket 41 engages radially. Pivoting the switching bracket 41 leads to an axial displacement of the switching sleeve 35 via an axial positive connection with the groove 40 and thus to an activation or deactivation of the inhibiting stage 5.

By activating the inhibiting stage 5, a user can prevent an external torque acting on the output shaft 6 from being transmitted to the reduction stage 4.

The drive shaft 3, which carries the eccentrics 10 rotating around the main axis 8, is a drive-side member of the reduction stage 4. The disk 19, which carries the drivers 18, is an output-side member of the reduction stage 4. The disk 19, which carries the eccentrics 22, is also a drive-side member of the arresting stage 5. The disk 30 is an output-side member of the arresting stage 5. By having these members concentric with the main axis 8, a balance of the mobile machine tool 1 is improved for a user. In particular, a "swing" or reaction torque during rapid speed changes is improved.

The Fig. 6 to 9 show a mobile machine tool 1 according to a second embodiment of the invention.

The machine tool 1 also has a drive shaft 3, a gear 2 containing a reduction stage 4 and a braking stage 5, as well as an output shaft 6.

The gear stages 4, 5 are housed in a gear housing 7.

The drive shaft 3, the gear stages 4, 5 and the output shaft 6 are concentric to a main axis 8.

In the second embodiment, the reduction stage 4 is designed as a switchable stepped planetary gear stage 42. The drive shaft 3 is designed as a sun gear 43 with a toothing. Three stepped planet gears 44 rotate around the sun gear 43. Each stepped planet gear 44 has a planetary stage 45 with a large diameter and a planetary stage 46 with a small diameter. The planet gears 44 run on planetary axes 47 that are fixed to a planet carrier 48. Each of the two planetary stages 45, 46 of the planet gears 44 is surrounded by a ring gear 49, 50. Due to the different diameters of the planetary stages 45, 46, the two ring gears 49, 50 have correspondingly different inner diameters.

Both ring gears have a locking toothing 51 on the outside radially. A shift sleeve 52 is guided in the circumferential direction in the transmission housing 7 by means of sliding pieces 53. By pivoting a shift bracket 54, which engages axially in a groove 55 of the shift sleeve 52 in a form-fitting manner, the shift sleeve 52 can be selectively switched back and forth between two switching positions. In each of the switching positions, a locking toothing 56 of the shift sleeve engages in the locking toothing 51 of only one of the ring gears 49, 50.

In this way, in both switching positions, exactly one of the ring gears 49, 50 is short-circuited in the circumferential direction against the gear housing 7, while the other of the ring gears 50, 49 can rotate freely in the circumferential direction. If a torque is applied to the planet gears 44 by the sun gear 43, this torque is supported by the ring gear 49, 50 short-circuited with the gear housing 7, so that the planet gears 44 are forced to rotate around the sun gear 43 and rotate the planet carrier 48. Because the planetary stages 45, 46 and the ring gears 49, 50 are stepped, a different transmission ratio results depending on the switching position. This means, for example, that a particularly wide transmission spread can be achieved.

Therefore, the planetary gear stage 42 is designed to reduce a fast speed of the drive shaft 3 to a slower speed of the planet carrier and preferably to translate a low torque in the drive shaft 3 into a high torque in the planet carrier 48.

The planetary gear stage 42 is therefore a reduction stage 4 with switchable reduction.

The inhibiting stage 5 is arranged on the output side of the reduction stage 4.

The following describes a stress wave transmission stage 57 which is used as the inhibition stage 5.

An ellipse 58 that is concentric with the main axis 8 and extends axially is formed in one piece on the planet carrier 48. The ellipse 58 thus forms an elliptical rolling surface. Rotating rollers 59 that form a rolling bearing are supported radially on the outside of the ellipse 58. The rollers 59 support a sleeve 60 that rotates radially on the outside. The sleeve 60 is preferably flexible around the main axis 8 in order to achieve a smooth elliptical rotation with low losses.

The sleeve 60 has an external toothing 61 on the outside radially. The external toothing 61 is surrounded on the outside radially by an internal toothing 62 of a shift sleeve 63. In the extension of a main axis of the ellipse 58 on both sides, the external toothing 61 and the internal toothing 62 mesh in sections, and in the extension of a minor axis of the ellipse 58 on both sides, the external toothing 61 and the internal toothing 62 do not mesh with each other in sections.

The sleeve 60 is also formed in one piece with axially projecting claws 64. These claws 64 permanently mesh with radial projections 65 or cams that project radially outward from a driven disk 66. The driven disk 66 also has a radially inner polygonal contour 31, which forms a shaft-hub connection with a polygonal contour 32 of the output shaft 6.

The shift sleeve 63 has a circumferential groove 67 into which a shift bracket 68 engages in a form-fitting manner in the axial direction. By pivoting the shift bracket 68, the shift sleeve 63 can be axially displaced selectively between two switching positions.

In a first switching position of the shift sleeve 63, the internal toothing 62 of the shift sleeve 63 meshes with the external toothing 61 of the sleeve 60 and at the same time with an external toothing 69 of the planet carrier 48, which is a drive-side element or input element of the stress wave gear stage 57. As a result, the stress wave gear stage 57 is short-circuited and switched off.

In a second switching position of the shift sleeve 63, a locking toothing 70 arranged radially on the outside of the shift sleeve 63 meshes with an opposing locking toothing 71 on the inside of the gear housing 7. In this switching position, the internal toothing 62 of the shift sleeve 63 is connected to the external toothing 61 of the sleeve 60 to support a torque. In this way, a fast rotation of the ellipse 58 is reduced to a slow rotation of the sleeve 60 and the output disk 66 meshing with it. A low torque in the ellipse 58 or the planet carrier 48 is translated into a high torque in the output disk 66. The stress wave transmission stage 57 is connected in this switching position.

The tension wave gear stage 57 has a self-locking effect due to its design. If the tension wave gear stage 57 is switched on, the transmission of torque from the output disk 66 to the ellipse 58 or the planet carrier 48 is inhibited or prevented. The tension wave gear stage 57 therefore acts as a switchable inhibiting stage 5. By switching on the inhibiting stage, a user can thus prevent the drive shaft 3 from rotating if an external torque is transmitted from a tool interface to the output shaft.

The sun gear 43 is a drive-side member of the reduction stage 4. The planet carrier 48 is an output-side member of the reduction stage 4. The ellipse 58 is a drive-side member of the brake stage 5. The disk 66 is an output-side member of the brake stage 5. By making these members concentric with the main axis 8, a balance of the mobile machine tool 1 is improved for a user. In particular, a "swing" or reaction torque during rapid speed changes is improved.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

LIST OF REFERENCE SYMBOLS

1

Machine tool

2

transmission

3

drive shaft

4

Reduction stage

5

Inhibition level

6

Output shaft

7

Gearbox housing

8th

Main axis

9

circuit

10

eccentric

11

Eccentric axis

12

Cycloid disk

13

Rollers

14

Roller bearing ring

15

External gearing

16

cam

17

Driving contour

18

Driver

19

disc

20

Cycloidal gear stage

21

Cycloidal gear stage

22

eccentric

23

Cycloid disk

24

External gearing

25

cam

26

roller

27

Roller bearing ring

28

Driving contour

29

Driver

30

disc

31

Polygon contour

32

Polygon contour

33

Eccentric axis

34

External gearing

35

Shift sleeve

36

Internal gearing

37

External gearing

38

External gearing

39

Internal gearing

40

Groove

41

Shift lever

42

Planetary gear stage

43

Sun gear

44

Planetary gear

45

Planetary stage

46

Planetary stage

47

Planetary axis

48

Planet carrier

49

Ring gear

50

Ring gear

51

Locking teeth

52

Shift sleeve

53

Sliding piece

54

Shift lever

55

Groove

56

Locking teeth

57

Stress wave gear stage

58

ellipse

59

roller

60

Sleeve

61

External gearing

62

Internal gearing

63

Shift sleeve

64

To steal

65

head Start

66

Driven pulley

67

Groove

68

Shift lever

69

External gearing

70

Locking teeth

71

Locking teeth

Claims (10)

Mobile machine tool (1), comprising a multi-stage transmission (2), wherein a drive shaft (3) of the transmission (2) and an output shaft (6) of the transmission (2) are arranged concentrically to a main axis (8), wherein the transmission (2) has at least one reduction stage (4) which is designed to reduce a speed of the drive shaft (3) to a speed of the output shaft (6),
characterized in that the transmission (2) has at least one at least switchable inhibiting stage (5) which is arranged to inhibit a torque transmission from the output shaft (6) to the drive shaft (3). Machine tool (1) according to claim 1, wherein the inhibiting stage (5) is arranged on the output side of the reduction stage (4). Machine tool (1) according to one of claims 1 and 2, wherein the stages (4, 5) of the transmission (2) each have a drive-side member (3, 19, 43, 48, 58) and an output-side member (19, 30, 48, 66) which are concentric to the main axis (8). Machine tool (1) according to one of claims 1 - 3, wherein the inhibiting stage (5) contains a cycloid gear stage (21) and/or a stress wave gear stage (57). Machine tool (1) according to one of claims 1 - 4, wherein the reduction stage (4) contains a planetary gear stage (42), a cycloidal gear stage (20) and/or a stress wave gear stage. Machine tool (1) according to one of claims 4 or 5, wherein the cycloidal gear stage (21, 22) has at least two cycloidal disks (12, 23) which are symmetrically phase-shifted to one another in the direction of rotation. Machine tool (1) according to claim 6, wherein respective eccentrics (10, 22), which each eccentrically mount at least one of the at least two cycloid disks (12, 23), have eccentric diameters that increase in an assembly direction. Machine tool (1) according to one of claims 1 - 7, wherein a reduction ratio of the reduction stage (4) is from 1:2 to 1:20 and preferably from 1:5 to 1:15. Machine tool (1) according to one of claims 1 - 8, wherein the transmission (2) has a variable reduction ratio in addition to the switchability of the inhibiting stage (5), wherein preferably the reduction stage (4) is switchable. Machine tool (1) according to one of claims 1 - 9, further comprising a tool interface which is configured for at least temporarily attaching a tool, wherein the tool interface is rotationally coupled to the output shaft (6).

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