CUT-OFF CLUTCH

Description

[0001] The invention relates to a torque-dependent release clutch for an electric hand tool, in particular for a screwdriver, for the selective transmission of a torque from a drive shaft to an output shaft coaxial to the drive shaft, and to a method for operating an electric hand tool with such a release clutch.

[0002] The invention is described below using the example of a screwdriver. In particular, the invention is intended for use in an industrial screwdriver. However, this is not to be understood as a limitation. The invention can also be used in other electric hand tools, such as drills or grinders.

[0003] The screwdrivers or cordless screwdrivers considered here are used especially for industrial series screw connections, for example in the production of automobiles.

[0004] For bolted connections, especially those in industrial applications, a nominal tightening torque is often specified, which determines how the connection should be tightened. During the tightening process, the torque increases. Therefore, the screwdriver must interrupt the torque transmission and, in particular, switch off the screwdriver's motor when the nominal tightening torque is reached.

[0005] For this purpose, such screwdrivers have a shut-off clutch in their drive train, which opens when an adjustable torque is reached.

[0006] Such a disconnect clutch is known, for example, from EP 3 361 114 B1. This disconnect clutch comprises a first clutch element and a second clutch element, which interact to transmit a torque. At least one of the two clutch elements is movable relative to the other and is preloaded by a spring element. The two clutch elements are positively coupled via at least one ball, allowing a torque to be transmitted between them. At least one clutch element also has a cam element per ball as a positive-locking element. When the torque reaches a certain value, the ball, due to the circumferential force acting upon it, begins to move up the cam element at a pitch of less than 90 degrees (relative to the direction of the circumferential force). In this way, the clutch disengages or "opens" when this torque is exceeded.

[0007] Another shut-off clutch is known from DE 10 2020 130 665 A1. The two coupling elements are a cam ring and a switching ring, which are also axially preloaded against each other and positively coupled by balls. The cam ring has a circumferentially closed cam track with at least one switching cam, against which the ball rests when the shut-off clutch is closed. If a release torque is exceeded, the ball is guided into a free-running track formed in the cam ring, so that no torque can be transmitted between the two coupling elements.

[0008] The present invention is based on the objective of further improving a shut-off clutch for an electric hand-held power tool and of providing a method for operating an electric hand-held power tool with such a shut-off clutch.

[0009] This problem is solved by a disconnect clutch according to claim 1, an electric hand-held power tool with such a disconnect clutch according to claim 15, and by corresponding methods for operating it. Advantageous embodiments of the invention are contained in the dependent claims.

[0010] A torque-dependent release clutch according to the invention for an electric hand tool, in particular for a screwdriver, for the selective transmission of a torque from a drive shaft to an output shaft coaxial to the drive shaft, has the following features: a cam ring which can be connected to the drive shaft or the output shaft in a rotationally fixed manner, and a first guide ring which is axially non-displaceable and which can be connected to the other of the drive shaft and the output shaft in a rotationally fixed manner.

[0011] The disengagement clutch can be moved from a first switching position, in which the cam ring is connected to the first guide ring in a first direction of rotation, in particular in the axial direction from the drive shaft to the output shaft in a clockwise direction, to a second switching position, in which the cam ring is freely rotatable relative to the first guide ring.

[0012] Furthermore, the shut-off clutch according to the invention has: at least one switching element, in particular a ball, which is guided by the first guide ring in the circumferential direction and / or in the radial direction, and a second guide ring, wherein the cam ring and the second guide ring are axially preloaded against each other and receive the at least one switching element axially between them.

[0013] The cam ring is designed such that, when the shut-off clutch is in the first switching position, at least one switching element is deflected in the axial direction relative to the cam ring against the effect of the preload when a first release torque acting in the first direction of rotation is exceeded, thereby bringing the shut-off clutch into the second switching position.

[0014] This provides a robust and simply constructed shut-off clutch that opens reliably when the first release torque is exceeded, thus solving the problem of improving the shut-off clutch.

[0015] The inclusion of the at least one switching element between the cam ring and the second guide ring, which are axially preloaded against each other, together with the guidance of the at least one switching element in the circumferential direction and / or in the radial direction by the first guide ring, ensures that the movement of the at least one switching element is always controlled in all directions and that the shut-off clutch cannot assume any undefined states.

[0016] Since the axial preload acting on the at least one switching element occurs only between the cam ring and the second guide ring, and the first guide ring is not involved, it is possible, according to the invention, to arrange the first guide ring in a way that prevents axial displacement. This allows for a rotationally fixed connection between the first guide ring and the drive or...

[0017] The output shaft is easier to implement, especially through a rigid or even one-piece connection, than if the first guide ring had to be axially displaceable.

[0018] Accordingly, it is preferred that the cam ring is also axially fixed, since this simplifies the realization of a rotationally fixed connection between the cam ring and the drive or output shaft, rather than requiring axial displacement. Consequently, it is preferred that the second guide ring is axially displaceable instead, in order to achieve the axial preload between the cam ring and the second guide ring, as well as the deflection of the at least one switching element against this preload. The second guide ring, however, is not involved in the torque transmission from the drive shaft to the output shaft and therefore does not require a rotationally fixed connection to either of these shafts.

[0019] In particular, the following first application is supported by the shut-off clutch according to the invention: When producing a screw connection, especially one consisting of a screw with an external thread and a mating part, preferably a fastening section, particularly an opening, with an internal thread, in the clockwise rotation of the hand-held power tool, the shut-off clutch should open as soon as the nominal tightening torque of the screw connection is reached. In this case, the first release torque should therefore correspond to this nominal tightening torque. The first application thus consists of protecting the screw connection from excessive preload and thus from possible damage to the screw or the mating part.

[0020] In a preferred embodiment of the invention, the cam ring has: at least one recess, in particular a ball pocket, in which the at least one switching element is received in the first switching position, wherein the at least one recess forms a first switching cam against which the at least one switching element rests in the first switching position, a circumferentially closed free-running track on which the at least one switching element can rotate in the second switching position, and at least one guide track which connects the at least one recess and the free-running track and on which the at least one switching element can move from the at least one recess to the free-running track and vice versa.

[0021] The free-running track and the at least one guide track are preferably formed by elongated recesses in a surface of the cam ring, which preferably extends in a plane perpendicular to the axial direction. The free-running track and the at least one guide track thus preferably form grooves in the surface of the cam ring, which further preferably have a circular segment-shaped cross-section.

[0022] In this arrangement, at least one switching element can be deflected in the axial direction when the first release torque is exceeded, and the shut-off clutch can be brought into the second switching position by the at least one switching element moving from the at least one recess via the at least one guide track into the free-running track.

[0023] In this way, the first and second switching positions of the disconnect clutch can be defined simply and reliably by the position of the at least one switching element in the at least one recess or in the freewheel track. Furthermore, the circumferentially closed freewheel track allows the at least one switching element to rotate there for any length of time, thus enabling the disconnect clutch to remain in the second switching position, and therefore in the open state, for any length of time.

[0024] In a preferred embodiment of the invention described above, the axial level of the at least one guideway rises from the depression in the direction of the free-running track and is always lower than or equal to the axial level of the free-running track.

[0025] An axial level is defined as a depth in the surface of the cam ring, i.e., a deeper axial level means a deeper recess in the surface of the cam ring.

[0026] To ensure a reliable transition of a switching element from the free-running track to the guide track, the free-running track and the at least one guide track preferably have different levels in the axial direction. While the free-running track preferably has a constant level, the at least one guide track preferably rises continuously from the first switching cam at the at least one recess in the cam ring until it reaches the level of the free-running track at the junction or end of the two tracks. At this point, the free-running track and the at least one guide track preferably have the same radii or shapes and transition smoothly into each other.

[0027] Due to the different axial levels of the free-running track and the at least one outfeed track and their arrangement, a step-like transition preferably forms between these two tracks, arranged transversely to their direction of travel. This step-like transition preferably forms a guide. This ensures that a change of a switching element from the at least one outfeed track to the free-running track and vice versa can only occur at the interface between the free-running track and the at least one outfeed track.

[0028] The aforementioned guide at the transition between the at least one guide track and the freewheel track can be particularly advantageous if the shut-off clutch has more than one switching element and a guide track for each switching element. This guide ensures that all switching elements used switch between the freewheel track and one of the guide tracks simultaneously at the respective opening between them. This prevents a first switching element from switching into one of the guide tracks while a second switching element is still in the freewheel track during a change of direction of rotation.

[0029] In a further preferred embodiment of the invention, the axial deflection of the at least one switching element as a result of the first release torque can cause an axial displacement of the cam ring and / or the second guide ring, and the shut-off clutch further comprises a sensor which is configured to detect this displacement.

[0030] The detection of the axial displacement of the cam ring and / or the second guide ring can advantageously be used to identify the second switching position and thus the open state of the disengagement clutch. During operation of a hand-held power tool with a disengagement clutch according to the invention, the motor control for the drive motor of the power tool can then trigger a change in the motor's direction of rotation, causing the at least one switching element to return from the freewheel track, via the at least one guide track, to the at least one recess, thereby returning the disengagement clutch to the first switching position and closing it again.

[0031] In a further preferred embodiment of the invention, the first guide ring is designed as a cage ring with at least one through-opening, and the at least one switching element is received in the at least one through-opening.

[0032] By designing the first guide ring as a cage ring, the receiving space for the at least one switching element is closed, particularly in the radial direction, from the surroundings, so that the at least one switching element cannot leave the first guide ring even under the influence of centrifugal force during the rotation of the shut-off clutch and thus possibly "get lost" inside the housing of the hand-held power tool.

[0033] In one variant of the embodiment of the invention described above, the at least one through-opening has an elongated, in particular elongated, straight shape, the direction of extension of which is inclined relative to a radial direction. Alternatively, the through-opening can have a shape that deviates from a straight shape, for example, a slightly curved shape.

[0034] An inclination of the direction of extension of the at least one through-hole in the first guide ring relative to a radial direction is advantageous for the radial movement of the at least one switching element during the transition of the disengagement clutch from the first to the second switching position, during which the at least one switching element moves radially inwards. Due to the inclination of the direction of extension of the at least one through-hole relative to a radial direction, the at least one switching element can "slide down" the inner wall of the at least one through-hole as if on a sloping wall during this movement, thereby reducing friction and preventing self-locking between the at least one switching element and the first guide ring.

[0035] In a further variant of the embodiment of the invention described above, the first guide ring is arranged axially between the cam ring and the second guide ring, and the at least one switching element projects axially on both sides beyond the edge of the at least one through-opening.

[0036] By arranging the first guide ring axially between the cam ring and the second guide ring, positive guidance of the at least one switching element is achieved in all directions, namely axially between the cam ring and the second guide ring, as well as radially and / or circumferentially through the first guide ring.

[0037] The axial projection of the at least one switching element beyond the side surfaces of the first guide ring or beyond the edge of the at least one through-hole in the first guide ring further ensures that the second guide ring can always be in axial contact with the at least one switching element without colliding with the edge of the at least one through-hole. The edge of the at least one through-hole preferably lies in a plane with a side surface of the first guide ring. Likewise, it is ensured that the cam ring can always be in axial contact with the at least one switching element without colliding with the edge of the at least one through-hole in the first guide ring.The axial projection of the at least one switching element on both sides of the first guide ring is preferably dimensioned such that the above applies to every axial position of the at least one switching element in the recesses in the cam ring or in the at least one through-opening in the first guide ring.

[0038] In a variant embodiment of the invention with at least one recess in the cam ring, the at least one recess is arranged within the cam ring. This means that the recess, preferably in the form of a cavity or a spherical pocket, is arranged at a distance from the outer circumference of the cam ring. Preferably, the outer circumference of the cam ring is higher than the recess in the region of the recess, so that the recess is closed radially outwards.

[0039] This can have the advantage, similar to the design of the first guide ring as a cage ring, that at least one switching element cannot leave the cam ring under the influence of centrifugal force during the rotation of the shut-off clutch and thus potentially be "lost" inside the housing of the hand-held power tool.

[0040] In one embodiment of the embodiment described above, the at least one recess has an elongated shape, transitions at a first end into the at least one guide track, and has a lower axial level than the at least one guide track. The transition of the recess into the guide track forms the first switching cam.

[0041] This design of the at least one recess provides a simple way to form the first switching cam in the recesses in the cam ring, thereby enabling the at least one switching element to transition directly into the at least one exit track after traversing the first switching cam. The lower axial level of the at least one recess compared to the axial level of the at least one exit track simultaneously achieves the desired axial deflection of the at least one switching element when traversing the first switching cam.

[0042] In one variant of the last described variant of the invention, the transition at the first end of the at least one recess from the at least one recess into the at least one outflow track, viewed in the extension direction of the at least one recess and the at least one outflow track, is essentially smooth.

[0043] This can result in a smooth and – apart from the jerk caused by overcoming the first switching cam – jerk-free movement of the at least one switching element on its way from the at least one recess into the at least one exit track.

[0044] In a variant of the invention with at least one recess, one free-running track and at least one guide track in the cam ring, the free-running track has a constant axial level.

[0045] This results in a particularly smooth movement of the at least one switching element in the second switching state. This leads to a low-wear, low-vibration, and / or low-noise switching process. Additionally, the constant axial level of the freewheel track prevents any further axial deflection of the at least one switching element and any associated axial displacement of the cam ring and / or the second guide ring, thus ensuring reliable detection of the transition from the first to the second switching position and thereby also fulfilling the requirement to improve the disengagement clutch.

[0046] In a further embodiment of the invention with at least one recess, one free-running track and at least one guide track in the cam ring, the at least one guide track has at least partially the form of a logarithmic spiral.

[0047] This can also cause a smooth and jerk-free movement of the at least one switching element on the at least one guide path radially inwards.

[0048] In a further preferred embodiment of the invention, the shut-off clutch can be moved from a third switching position, in which the cam ring is connected to the first guide ring in a second direction of rotation opposite to the first direction of rotation, in particular in the axial direction from the drive shaft to the output shaft counterclockwise, to a fourth switching position, in which the cam ring is freely rotatable relative to the first guide ring.

[0049] The cam ring is designed such that, when the shut-off clutch is in the third switching position, at least one switching element is deflected axially relative to the cam ring against the effect of the preload when a second release torque acting in the second direction of rotation is exceeded, thereby bringing the shut-off clutch into the fourth switching position.

[0050] This provides a robust and simply constructed shut-off clutch that reliably opens when the second release torque is exceeded.

[0051] This embodiment of the cut-off clutch according to the invention particularly supports the following second application: When loosening a screw connection in reverse rotation of the hand-held power tool, it may be necessary, in the case of a seized screw connection, for the torque required to loosen it to be greater than the maximum motor torque. Operating the hand-held power tool with such a high torque could damage the motor. Therefore, the cut-off clutch should open before the maximum motor torque is reached. In this case, the second release torque should therefore be somewhat lower than the maximum motor torque. The second application thus consists of protecting the motor of the hand-held power tool from overload and damage.

[0052] In a preferred embodiment of the invention described above, in which at least one recess is further provided in the cam ring, the at least one switching element is received in the at least one recess in the third switching position, wherein a second switching cam is formed by the at least one recess, against which the at least one switching element rests in the third switching position.

[0053] The cam ring further has a cam track that is largely closed in the circumferential direction and interrupted only by at least one recess, on which the at least one switching element can rotate at least sectionally in the fourth switching position.

[0054] Furthermore, at least one switching element can be deflected in the axial direction when the second release torque is exceeded, and the shut-off clutch can be brought into the fourth switching position by the at least one switching element moving from the at least one recess into the cam track.

[0055] This design of the cam ring achieves essentially the same advantages as described above for the first and second switching positions, namely that the third and fourth switching positions of the disengagement clutch can be defined simply and reliably by the position of the at least one switching element in the at least one recess or in the cam track. In contrast to the second switching position, however, the fourth switching position is only maintained until the at least one switching element falls from the cam track into the next recess. The duration of this movement, however, can be sufficient to detect the fourth switching position and react to it.

[0056] In a preferred embodiment of the invention described above, the at least one recess has an elongated shape, transitions into the cam track at a second end and has a lower axial level than the cam track, whereby the second switching cam is formed by this transition.

[0057] This can result in the corresponding advantages as in the variant described above, in which the at least one recess transitions at a first end into the at least one guide track and has a lower axial level than the at least one guide track, whereby a first switching cam is formed by this transition.

[0058] Preferably, the second end of at least one depression, with respect to its elongated shape, lies opposite such a first end.

[0059] In a further preferred embodiment of the invention described above, the axial deflection of the at least one switching element as a result of the second release torque can cause an axial displacement of the cam ring and / or the second guide ring, and the shut-off clutch further comprises a sensor which is configured to detect this displacement.

[0060] This can be used – similarly to the second switching position described above – to detect the fourth switching position and thus the open state of the disconnect clutch. However, following this detection, a reversal of the motor's direction of rotation is not necessary, since in this case at least one switching element can remain in the cam track and, even if the motor continues to operate in the same direction, return to a recess, which is then the next recess in the circumferential direction, and thus the disconnect clutch can also return to the third switching position.

[0061] Naturally, the sensor for detecting the fourth switching position can be identical to the sensor for detecting the second switching position, since in both cases an axial displacement of the cam ring and / or the second guide ring is detected.

[0062] In a preferred embodiment of the invention in which the first and second switching cams are formed by a transition at a first and a second end of the at least one recess, respectively, the inner wall of the at least one recess at its second end is steeper than the inner wall of the at least one recess at its first end, so that the second release torque is greater than the first release torque.

[0063] The described relationship, namely that the release torque is greater the steeper the transition at the respective end of the at least one recess, results directly from the interaction described above between the at least one switching element and the respective inner wall of the at least one recess (the "ramp") in the sense of a wedge mechanism. The fact that the second release torque is greater than the first release torque can be advantageous, since the maximum motor torque, according to which the second release torque is to be dimensioned, is generally greater than the nominal tightening torque of a screw connection, according to which the first release torque is to be dimensioned.

[0064] In a further preferred embodiment of the invention described above, the cam track has a constant axial level, except in the area of ​​the at least one recess.

[0065] This can result in the same advantages as with the corresponding design with a constant axial level of the freewheel track, namely that in this case the transition from the third to the fourth switching position can be reliably detected.

[0066] In a further preferred embodiment of the invention, the shut-off clutch has a freewheel which can be opened and closed, which is designed to be supported against a housing of the electric hand tool, and which in the closed (activated) state allows rotation of the output shaft in the first direction of rotation and blocks rotation of the output shaft in the second direction of rotation, and in the open (deactivated) state does not affect the rotatability of the output shaft.

[0067] A freewheel with these functions is advantageous when, in the second switching position, the direction of rotation of the motor is reversed from the first to the second direction of rotation in order to return the at least one switching element from the freewheel track, via the at least one guide track, to the at least one recess. In this case, it is essential to prevent the output shaft from rotating, as otherwise the required relative rotation between the input and output shafts cannot be achieved. Therefore, in this case, the freewheel can be closed, thus blocking the rotation of the output shaft in the second direction of rotation and preventing it from rotating in that direction.

[0068] In a preferred embodiment of the invention described above, the freewheel is a pawl freewheel in which at least one pawl engages in at least one freewheel tooth. The at least one pawl is arranged on an axially displaceable, non-rotatable pawl ring which is axially preloaded against the at least one freewheel tooth, and the at least one freewheel tooth is arranged on an end face of the first guide ring.

[0069] The pawl-type freewheel design is a common and therefore easy to implement. In particular, using the first guide ring to mount the at least one freewheel tooth can be advantageous, as this eliminates the need for an additional component for the freewheel tooth.

[0070] In a preferred embodiment of the previously described embodiment of the invention, the freewheel can be closed and opened by an axial displacement of the freewheel pawl ring, which can be effected by an axial displacement of the second guide ring.

[0071] If the transition from the first to the second switching position and / or the transition from the third to the fourth switching position can cause an axial displacement of the second guide ring, it is also advantageous to effect the opening and closing of the freewheel by means of this displacement. Since the freewheel pawl ring is axially displaceable, it is further advantageous to effect the opening and closing of the freewheel by such an axial displacement of the freewheel pawl ring. In this way, the existing movement possibilities of the components involved are utilized for opening and closing the freewheel.

[0072] The axial displacement of the freewheel pawl ring caused by the axial displacement of the second guide ring can be direct or indirect. In a direct effect, the freewheel pawl ring can be directly supported axially by the second guide ring. In an indirect effect, at least one further force-transmitting component can be arranged between the second guide ring and the freewheel pawl ring, in particular a component connected to the second guide ring and axially displaceable with it, but not itself rotatable.

[0073] In a preferred embodiment of the previously described embodiment of the invention, the cam ring and the first guide ring are arranged axially between the freewheel pawl ring and the second guide ring, and the second guide ring or a component connected to the second guide ring and axially non-displaceable relative to it overlaps the cam ring and the first guide ring axially.

[0074] If the opening and closing of the freewheel is to be achieved by an axial displacement of the second guide ring and the resulting axial displacement of the freewheel pawl ring, the second guide ring must be able to act axially on the freewheel pawl ring. If the cam ring and the first guide ring are also located axially between them, this can be easily achieved by having the second guide ring, or a component connected to the second guide ring but not axially displaceable relative to it, axially overlap both of these latter components. This also includes the case where the axial displacement of the freewheel pawl ring is indirectly caused by the axial displacement of the second guide ring, and where another force-transmitting component, connected to the second guide ring but not axially displaceable relative to it, axially overlaps the cam ring and the first guide ring.

[0075] In a further preferred variant of the embodiment of the invention described above, the freewheel is open in the first switching position and closed in the second switching position.

[0076] This corresponds to the requirement that the freewheel should be closed when, after the transition from the first to the second switching position, the direction of rotation of the motor is reversed from the first to the second direction of rotation in order to prevent the output shaft from rotating in the second direction of rotation.

[0077] In contrast, since a reversal of the motor's direction of rotation is not required after the transition from the third to the fourth switching position, as described above, it is irrelevant in this case whether the freewheel is closed or open.

[0078] The invention further relates to an electric hand-held power tool, in particular a screwdriver, with a cut-off clutch according to the invention. This allows the two application cases described above for clockwise and counterclockwise rotation of the hand-held power tool's motor to be implemented simply and reliably.

[0079] The invention also relates to a method for operating an electric hand-held power tool, in particular a screwdriver, with a cut-off clutch according to the invention, which comprises the steps: Driving the drive shaft in the first direction of rotation while the disengagement clutch is in the first switching position, stopping the rotation of the drive shaft when a torque exceeding the first release torque acts in the first direction of rotation, whereby the disengagement clutch is moved into the second switching position by exceeding the first release torque, driving the drive shaft in the second direction of rotation, thereby moving the disengagement clutch back into the first switching position.

[0080] This corresponds to the first application case already described in detail above, in which the shut-off clutch should open as soon as the nominal tightening torque of the screw connection to be manufactured is reached, and then close again.

[0081] The invention also relates to a method for operating an electric hand tool, in particular a screwdriver, with a shut-off clutch which can further be moved into the third and fourth switching positions, comprising the following steps: Driving the drive shaft in the second direction of rotation while the disengagement clutch is in the third switching position, further driving the drive shaft in the second direction of rotation when a torque acts in the second direction of rotation which exceeds the second release torque, whereby the disengagement clutch is brought into the fourth switching position by exceeding the second release torque, further driving the drive shaft in the second direction of rotation, whereby the disengagement clutch is brought back into the third switching position.

[0082] This corresponds to the second use case, which has already been described in detail above, in which the shut-off clutch should open before the maximum motor torque is reached in order to protect the motor from overload, and then close again afterwards.

[0083] Further advantages, features and applications of the present invention will become apparent from the following description in conjunction with the figures. These show: Fig. 1 a side view of a shut-off clutch according to the invention; Fig. 2 a section through the shut-off clutch according to the invention. Fig. 1 ; Fig. 3 an exploded view of the shut-off clutch according to Fig. 1 ; Fig. 4 the components of the shut-off clutch according to Fig. 1 , which form the clutch mechanism; Fig. 5 the face of the cam ring of the shut-off clutch according to Fig. 1 ; Fig. 6 the components of the shut-off clutch according to Fig. 1 , which form the reset mechanism.

[0084] The invention is described in detail below with reference to a single embodiment of a disconnect clutch 1 according to the invention. Here, the Fig. 1 , 2 and 3 the entire shut-off clutch 1 in different views, namely as a side view ( Fig. 1 ), cut ( Fig. 2 ) and exploded view ( Fig. 3 ). The Fig. 4 , 5 and 6 show individual components or sub-assemblies of the shut-off clutch 1, namely the clutch mechanism which causes the shut-off clutch 1 to open and close ( Fig. 4 ), the front face of the cam ring 7 with the various recesses 30 to 35 for the balls 11 ( Fig. 5 ) as well as the reset mechanism, which closes a freewheel when the shut-off clutch 1 is opened ( Fig. 6 ).

[0085] The shut-off clutch 1 is designed for installation in an electric, rotating hand-held power tool (not shown in the figures), in particular in a screwdriver, such as those used in industrial manufacturing. The shut-off clutch 1 is arranged in the drive train of the hand-held power tool between the drive motor and a tool holder, in particular for a screwdriving tool such as a screwdriver bit or an internal or external hexagonal tool. However, the shut-off clutch 1 according to the invention can also be used in other hand-held power tools.

[0086] The components of the shut-off clutch 1 are essentially all arranged coaxially around an axis, which simultaneously forms the axis of rotation of the rotatable components. At the same time, the shut-off clutch 1 is supported by a housing-fixed ring 48 on the housing of the hand-held power tool (not shown) and is rigidly connected to the housing directly or indirectly at this point.

[0087] The disconnect clutch 1 has a drive shaft 2, the outer end of which is, for example, designed in the form of an external hexagon 20. The external hexagon 20 is designed for a permanent, positive-locking, and rotationally fixed coupling with the drive motor (not shown) of the hand-held power tool. Coaxial to the drive shaft 2, the disconnect clutch 1 has an output shaft 3, at the outer end of which an internal hexagon 21 is formed. The internal hexagon 21 is designed for the positive-locking, rotationally fixed reception of interchangeable tools, in particular screwdriver bits of any type (not shown). The tools are preferably inserted into the internal hexagon 21 by hand and are preferably held in place by friction, a locking mechanism, or magnetically.

[0088] The drive shaft 2 and the output shaft 3 are rotatably mounted relative to each other by a ball bearing 17. During the assembly of the shut-off clutch 1, the balls of the ball bearing 17 are individually inserted through a radial bore in the outer bearing shell of the drive shaft 2, and this bore is then closed with a plug 18.

[0089] The shut-off clutch 1 has the function of transmitting torque from the drive shaft 2, and thus from the drive motor, to the output shaft 3, and thus to the tool, when the hand-held power tool is in the closed position. As soon as the torque transmitted from the drive shaft 2 to the output shaft 3 exceeds a certain, adjustable release torque, the shut-off clutch 1 should open so that no further torque can be transmitted from the drive shaft 2 to the output shaft 3.

[0090] In particular, the opening of the shut-off clutch 1 upon exceeding the release torque is intended to support the two application scenarios described above: When tightening a screw connection in the clockwise direction of the hand-held power tool, the shut-off clutch 1 should open as soon as the nominal tightening torque of the screw connection is reached (first application scenario). Conversely, when loosening a screw connection in the counterclockwise direction of the hand-held power tool, the shut-off clutch 1 should open when the required loosening torque is greater than the maximum motor torque, in order to protect the motor of the hand-held power tool from overload (second application scenario).

[0091] Since the two applications differ, the required release torque can also differ. In particular, because the nominal tightening torque varies from one bolted connection to another in the first application, the release torque should be preselectable by the user of the hand-held power tool.

[0092] To achieve the desired opening of the shut-off clutch 1 when the respective release torque is exceeded in clockwise or counterclockwise rotation, the drive shaft 2 is rotationally fixed – and in the exemplary embodiment, integrally connected – to a cam ring 7. Various recesses with different axial levels are formed in the end face of the cam ring 7, which faces axially towards the output shaft 3. These recesses are designed to accommodate several balls 11, in the exemplary embodiment three, which can move within them essentially in the circumferential direction. The exact arrangement and function of the recesses in the cam ring 7 are described in detail below.

[0093] For each ball 11, at least one point is provided in the recesses in the cam ring 7 where the axial level of the recess changes abruptly. In other words, the recess has an axial step at this point. However, the "vertical" wall of the step does not run exactly in the axial direction, but is inclined relative to it, such that the step forms a steep, but not perpendicular, ramp from the lower axial level (in the sense of a deeper recess in the face of the cam ring 7) to the higher axial level.

[0094] In the closed state of the shut-off clutch 1, the ball 11 is located in the recess on the side of the step with the lower axial level and rests against the step in such a way that, with a predetermined direction of rotation of the drive shaft 2, the step presses against the ball 11 in the circumferential direction. In this way, a torque can initially be transmitted from the cam ring 7 to the ball 11 in this state of the shut-off clutch 1. The shut-off clutch 1 is then in a first switching position.

[0095] A first guide ring 8 is arranged axially adjacent to the cam ring 7 and is connected to the output shaft 3 in a rotationally fixed manner – in the exemplary embodiment as a single piece. Thus, both the cam ring 7 and the first guide ring 8 are axially immovable.

[0096] The first guide ring 8 has a through-hole 10 for each ball 11, in which the portion of the ball 11 projecting axially beyond the cam ring 7 is guided. Each through-hole 10 is straight, i.e., in the form of an elongated slot, and extends within the first guide ring 8 from a radially outer end to a radially inner end in a direction oblique to the radial direction. The radially outer end of the elongated slot is spaced apart from the outer circumference of the first guide ring 8. This results in each ball 11 being guided tightly within an elongated slot. The loss of a ball 11 is therefore impossible.The axial extension of the first guide ring 8 is dimensioned such that each ball 11, in every possible position it can assume in a recess in the cam ring 7, bears with its largest diameter against the inner walls of the associated through-hole 10, and that simultaneously a portion of the ball 11 protrudes axially from the through-hole 10 on the side opposite the cam ring 7. The first guide ring 8 with the through-holes 10 arranged within it thus acts like a cage for the balls 11. In this way, a torque can always be transmitted between the balls 11 and the second guide ring 8, and thus to the output shaft 3.

[0097] On the side of the first guide ring 8 opposite the cam ring 7, a second guide ring 9 is arranged, the end face of which facing the first guide ring 8 being completely flat. The second guide ring 9 is rotatably and axially displaceably mounted on the output shaft 3, preferably by a plain bearing. As will be explained in more detail below, the second guide ring 9 is axially preloaded against the cam ring 7, so that its flat end face is pressed against the balls 11.

[0098] In this way, the balls 11 are positively guided in all directions, namely axially by the recesses in the face of the cam ring 7 and by the flat face of the second guide ring 9, and radially and circumferentially by the through-openings 10 in the first guide ring 8. This positive guidance of the balls 11 prevents them from moving uncontrollably during the rotation of the drive shaft 2 and the output shaft 3 and from being lost inside the housing of the hand-held power tool.

[0099] Based on the description so far, it is clear that when the shut-off clutch 1 is closed, torque can be transmitted from the drive shaft 2 via the cam ring 7, the balls 11, and the first guide ring 8 to the output shaft 3. The second guide ring 9 is not involved in the torque transmission itself, but forms part of the axial guidance of the balls 11.

[0100] As mentioned above, when the shut-off clutch 1 is closed, each ball 11 rests against its corresponding step in a recess in the end face of the cam ring 7. The step forms a steep, but not vertical, ramp, and a torque in the predetermined direction of rotation of the drive shaft 2 can be transmitted from the ramp to the ball 11. The surface of the ball 11 and the ramp form a wedge mechanism. Simultaneously, the ball 11 is axially preloaded against the end face of the cam ring 7 by the second guide ring 9. This preload is dimensioned such that when the torque transmitted between the ramp and the ball 11 exceeds a first release torque, the ball 11 "rises" up the ramp due to the wedge action and enters the axially higher part of the recess in the end face of the cam ring 7.

[0101] As will be explained in more detail below, this recess is arranged such that the ball 11 can move freely in the circumferential direction within the axially higher part of the recess. In this state of the disengagement clutch 1, no torque can be transmitted between the cam ring 7 and the ball 11 – and therefore also no longer between the drive shaft 2 and the output shaft 3. The disengagement clutch 1 is then in a second switching position and in the open state.

[0102] The ramp in the recess in the end face of the cam ring 7 thus acts as a first switching cam 31, the traversal of which by the ball 11 in a first direction of rotation causes the shut-off clutch 1 to transition from the closed state to the open state. In a second direction of rotation, opposite to the first, this ramp also acts as a first switching cam 31, the traversal of which by the ball 11 causes the shut-off clutch to transition from the open state to the closed state.

[0103] The end face of the cam ring 7 with the recesses for the balls 11 is now described in detail. In the exemplary embodiment, three balls 11 are provided, and the end face of the cam ring 7 has recesses for each ball 11 offset by 120 degrees, thus exhibiting threefold rotational symmetry.

[0104] The recesses for a ball 11 initially comprise an elongated ball pocket 30, which has a lower axial level than all other recesses in the face of the cam ring 7. The ball pocket 30 extends approximately circumferentially, but is slightly curved radially inwards towards one end.

[0105] The two ends of the ball pocket 30, where the lower axial level of the ball pocket 30 transitions into the higher axial level of the surroundings of the ball pocket 30, thus form a first switching cam 31 for torque transmission during a clockwise rotation and a second switching cam 32 for torque transmission during a counterclockwise rotation of the drive shaft 2 to the output shaft 3.

[0106] When the first release torque is exceeded during a clockwise rotation of the drive shaft 2, the ball 11, as described above, overcomes the first switching cam 31 and enters the subsequent guide track 33, which spirals radially inwards. The guide track 33 preferably has the form of a logarithmic spiral to enable smooth, jerk-free movement of the ball 11. The slight radial inward curvature of the ball pocket 30 is also selected such that the ball pocket 30 transitions smoothly into the guide track 33, likewise enabling smooth, jerk-free movement of the ball 11.

[0107] Simultaneously with its radial inward movement in the guide track 33, the ball 11 also moves radially inward along the longitudinal extent of the through-opening 10 in the first guide ring 8. Since the through-opening 10 is not arranged radially, but inclined relative to a radial direction, the ball 11 can slide down the inner surface of the through-opening 10 at an oblique angle, thereby reducing friction and preventing possible self-locking during the movement of the ball 11 in the through-opening 10.

[0108] The outflow track 33 opens in the radially inner area of ​​the front face of the cam ring 7 into a closed, circular free-running track 34 with a constant axial level, in which the ball 11 can circulate for any length of time.

[0109] When the ball 11 is located in the guide track 33 or in the freewheel track 34, and thus no mechanical resistance is encountered in the circumferential direction, no torque can be transmitted from the drive shaft 2 to the output shaft 3. The shut-off clutch 1 is then consequently in the open position and thus prevents the nominal tightening torque of a bolted connection from being exceeded.

[0110] Since the guide track 33 and the freewheel track 34 have a higher axial level than the ball pocket 30, the ball 11 moves in an axial direction towards the output shaft 3. This also displaces the second guide ring 9, which is preloaded against the balls 11 and the cam ring 7, in this axial direction.

[0111] The second guide ring 9 is rotatably mounted relative to a sliding ring 40, whose function will be described in more detail later, by means of a ball bearing 6, so that the sliding ring 40 itself does not rotate. The second guide ring 9 and the sliding ring 40 are connected to form a single unit by the ball bearing 6 and therefore cannot move axially relative to each other, but can only be moved axially together.

[0112] The sliding ring 40 has an opening 42 on its outer circumference, which can contain a position indicator, for example a permanent magnet (not shown). A corresponding sensor, for example a magnetic sensor (also not shown), is mounted in the housing of the hand-held power tool, which can detect the axial displacement of the position indicator and thus of the sliding ring 40.

[0113] The sensor detects, based on the axial displacement of the sliding ring 40, that the shut-off clutch 1 has moved into the open position and transmits a corresponding signal to the control unit of the drive motor of the hand-held power tool. The motor is then switched off. After the motor's rotation has ceased, the direction of rotation of the drive shaft 2 is reversed. The ball 11, which is in the freewheel track 34 (in the Fig. 5 The cam ring 7, which rotates clockwise in the orientation shown, rotates counterclockwise after the direction of rotation is reversed. At the "branch" or opening 36, it passes from one of the discharge tracks 33 back into that discharge track 33 and at its end back into the corresponding ball pocket 30. The guide 37, created by the arrangement and the different levels of the free-running track 34 and the discharge track 33, ensures that the ball 11 always changes from the free-running track 34 to the discharge track 33 at the opening 36. This is particularly important if the shut-off clutch 1 includes more than one ball 11. This prevents one ball 11 from being in the free-running track 34 and another ball 11 from being in the discharge track 33. This ensures reliable opening and closing of the shut-off clutch 1.The renewed axial movement of the sliding ring 40 towards the drive shaft 2, associated with the transfer of the ball 11 into the ball pocket 30, is again detected by the sensor, whereupon the motor control stops the motor's rotation. The shut-off clutch 1 is thus back in the closed state.

[0114] When the drive shaft 2 rotates counterclockwise, the ball 11 rests against the end of the ball pocket 30 on the second switching cam 32 opposite the first switching cam 31, so that a torque can be transmitted from the cam ring 7 to the ball 11 and, as described above, via the first guide ring 8 to the output shaft 3. The disengagement clutch 1 is then in a third switching position.

[0115] If, during the counterclockwise rotation of the drive shaft 2, the second release torque is exceeded, the ball 11 overcomes the second switching cam 32 and enters the subsequent cam track 35. The cam track 35 runs circularly around the outer radial edge of the cam ring 7, concentric to the freewheel track 34, and is interrupted only by the ball pockets 30. Apart from the ball pockets 30, the cam track 35 maintains a constant axial level, which is higher than that of the ball pockets 30.

[0116] Preferably, the ramp at the end of the ball pocket 30, which forms the second switching cam 32, is steeper than the ramp at the end of the ball pocket 30, which forms the first switching cam 31. This preferably results in the second release torque being greater than the first release torque.

[0117] In the cam track 35, the ball 11 can rotate at least as far as the next ball pocket 30, i.e., over a rotational angle range of 5 degrees to 120 degrees, without encountering any mechanical resistance in the circumferential direction. Thus, during this movement of the ball 11, no torque can be transmitted from the drive shaft 2 to the output shaft 3. The shut-off clutch 1 is then in its fourth switching position. In this fourth switching position, the shut-off clutch 1 is also open and prevents the maximum motor torque from being exceeded, particularly if this torque is insufficient to loosen a bolted connection.

[0118] In this case as well, the sliding ring 40 is axially displaced when the shut-off clutch 1 opens, which is detected by the sensor. The motor control then allows the motor to continue rotating counterclockwise, for example at a low speed, until each ball 11 has fallen back into its respective ball pocket 30. Reversing the motor's direction of rotation beforehand is not necessary in this case. The shut-off clutch 1 is then closed again. It is even unnecessary to let the motor run at a low speed, since the balls 11 will fall back into their respective ball pockets 30 the next time the power tool is used – regardless of whether it is in clockwise or counterclockwise rotation – and the shut-off clutch 1 will then be closed again.

[0119] The first and second release torques can be preset depending on the desired application, in particular depending on the nominal tightening torque of a screw connection to be produced, via the axial preload of the second guide ring 9 against the balls 11 and the cam ring 7.

[0120] This preload is generated by an axially preloaded compression spring 12, which is designed as a coil spring and runs around the output shaft 3. The compression spring 12 is supported at one end by the second guide ring 9 and at the other end by a pressure ring 13, which has a projection (not shown) on its inner side that engages in a flat 5 ( Fig. 6 The pressure ring 13 engages with the output shaft 3 and is therefore axially displaceable relative to the output shaft 3, but not rotatable. On the side of the pressure ring 13 facing away from the compression spring 12, an adjusting ring 15 is screwed onto a thread 4 of the output shaft 3. The thread 4 is preferably a left-hand thread. Several (in the exemplary embodiment, six) detent balls 14 are embedded at equal angular intervals in the end face of the pressure ring 13 facing the adjusting ring 15. These detent balls can engage in several (in the exemplary embodiment, twelve), also at equal angular intervals, bores 16 on the opposite end face of the adjusting ring 15. The adjusting ring 15 can thus be rotated against the spring force of the compression spring 12 by a specific angle (in the exemplary embodiment, 30 degrees), which the user perceives as individual detents, and can thereby be further screwed onto or unscrewed from the output shaft 3.With each detent position, the preload of the compression spring 12 increases or decreases, and thus the first and second release torques. In the hand-held power tool, the adjusting ring 15 is surrounded by an actuating ring (not shown), preferably made of a grippy plastic, which can be easily adjusted by hand.

[0121] As described above, the motor's direction of rotation is briefly reversed from clockwise to counterclockwise when the clutch opens due to exceeding the initial release torque. This causes the balls 11 to return to their ball pockets 30 by a counterclockwise rotation of the drive shaft 2 and thus the cam ring 7 relative to the balls 11, and the disengagement clutch 1 to close again after opening. Since the balls 11 are positively guided by the first guide ring 8, and the first guide ring 8 is rotationally fixed to the output shaft 3, it is essential to prevent the output shaft 3 from rotating with the drive shaft 2 during its counterclockwise rotation. Otherwise, such a relative rotation between the drive shaft 2 and the output shaft 3 would not occur.

[0122] Rotation of the output shaft 3 can be prevented, for example, by ensuring that the tool remains engaged with the previously tightened screw after the motor's direction of rotation has been reversed. However, in practical use of the hand-held power tool, it cannot be guaranteed that the user will keep the tool engaged with the screw immediately after reaching the nominal tightening torque and the associated opening of the shut-off clutch 1. Once the tool is disengaged from the screw, rotation of the output shaft 3 can no longer be prevented.

[0123] To reliably prevent the output shaft 3 from rotating in any state of the shut-off clutch 1 after reversing the direction of rotation of the motor, i.e., when the motor is running counter-clockwise, the shut-off clutch 1 has a reset mechanism, which is described below (see also Fig. 6 ).

[0124] The reset mechanism is triggered when the shut-off clutch 1 is opened by the previously described axial movement of the sliding ring 40. As is best done in Fig. 2 As can be seen, the sliding ring 40 engages radially on its outer surface with several (in the exemplary embodiment, three) claws 41 distributed around its circumference, directed towards the drive shaft 2 and oriented towards the drive shaft 2. These claws 41 bear against the second guide ring 9, the first guide ring 8, the balls 11, and the cam ring 7. The claws 41 bear against a radially outer region of the end face of a freewheel pawl ring 43, which has a diameter approximately the same as the sliding ring 40 and thus a slightly larger diameter than the cam ring 7, the first guide ring 8, and the second guide ring 9. Instead of several claws 41, the sliding ring 40 can also have a circumferential, cylindrical surface, which likewise bears against the radially outer region of the end face of the freewheel pawl ring 43.

[0125] The freewheel pawl ring 43 is axially displaceable but not rotatable, as it is guided axially by several axially arranged guide pins 51. For this purpose, the freewheel pawl ring 43 has grooves 52 which, together with the guide pins 51, form an axial sliding guide. The guide pins 51 are, in turn, rigidly connected to the outside of a cylindrical section 49 of a housing-mounted ring 48 by being inserted into grooves 53 in the cylindrical section 49 of the housing-mounted ring 48. The housing-mounted ring 48 is rigidly connected to the housing of the power tool via several recesses 50 around its circumference and projections (not shown) in the housing of the power tool, and is therefore neither axially displaceable nor rotatable. In this way, the freewheel pawl ring 43 is axially displaceable on the cylindrical section 49 of the housing-fixed ring 48, but cannot rotate due to the guidance provided by the guide pins 51.

[0126] The housing-mounted ring 48 also serves to radially support a ball bearing 22 from the outside, in which the drive shaft 2 is radially mounted inside. The bearing between the housing-mounted ring 48 and the drive shaft 2 is further secured by a retaining ring 19.

[0127] Furthermore, a wave spring 47 is arranged between a flange of the housing-mounted ring 48, which has a larger diameter than that of the cylindrical section 49, and a flange of the freewheel pawl ring 43, which has approximately the same diameter as that of the flange of the housing-mounted ring 48. This wave spring preloads the freewheel pawl ring 43 axially in the direction of the output shaft 3. Instead of a wave spring, another compression spring, in particular a coil spring, can also be used for this purpose.

[0128] The spring force of the wave spring 47 is always less than the spring force of the compression spring 12, so that the preload of the unit consisting of the sliding ring 40 and the second guide ring 9 against the balls 11 is not eliminated.

[0129] The freewheel pawl ring 43 has several projections distributed around its circumference on its end face facing the first guide ring 8, which serve as freewheel pawls 44 ( Fig. 6 The end face 45 of a cylindrical extension of the first guide ring 8, which radially overlaps the cam ring 7 axially, has a sawtooth profile in the circumferential direction. This forms several freewheel teeth 46 into which the freewheel pawls 44 can engage. In the open state of the disengagement clutch 1, when the balls 11 are outside the ball pockets 30, the freewheel pawl ring 43 is pressed axially against the first guide ring 8 by the spring force of the wave spring 47. The freewheel pawls 44 can then engage with the freewheel teeth 46, and the freewheel is in the closed state. The direction of the sawtooth profile of the end face 45 of the cylindrical extension of the first guide ring 8, and thus the arrangement of the freewheel teeth 46, is chosen such that the first guide ring 8, and therefore the output shaft 3, can only rotate clockwise, but not counterclockwise.

[0130] With the shut-off clutch 1 closed, the claws 41 of the sliding ring 40 push the freewheel pawl ring 43 axially away from the first guide ring 8 against the spring force of the wave spring 47, so that the freewheel pawls 44 cannot engage in the freewheel teeth 46 and the freewheel is open and has no effect.

[0131] With the disengagement clutch 1 open, the jaws 41 of the sliding ring 40 do not press against the freewheel pawl ring 43, because the unit consisting of the sliding ring 40 and the second guide ring 9 is axially displaced by the balls 11 in the direction of the output shaft 3. This causes the wave spring 47 to press the freewheel pawl ring 43 axially against the first guide ring 8, allowing the freewheel pawls 44 to engage the freewheel teeth 46 and the freewheel to close. This results in the desired behavior of the freewheel: it is only closed when the disengagement clutch 1 is open, which is also when the direction of rotation of the motor reverses. Therefore, when the motor is running counterclockwise, the output shaft 3 is prevented from rotating.

[0132] In the event that the shut-off clutch 1 opens due to exceeding the second release torque during counter-clockwise rotation of the motor, the freewheel closes, and the balls 11 are located in the cam track 35. However, this has no further effect, since, as described above, in this case the balls do not need to return from the freewheel track 34 to the ball pockets 30, and therefore a reversal of the motor's direction of rotation is not required, which would prevent the output shaft 3 from rotating. The change of state from the open to the closed state of the freewheel has no effect when the shut-off clutch 1 opens during counter-clockwise rotation of the motor. Bezugszeichenliste

[0133] 1 Disconnect clutch 2 Input shaft 3 Output shaft 4 Thread 5 Flat 6 Ball bearing 7 Cam ring 8 First guide ring 9 Second guide ring 10 Through opening 11 Ball 12 Compression spring 13 Pressure ring 14 Detent ball 15 Adjusting ring 16 Bore 17 Ball bearing 18 Plug 19 Retaining ring 20 External hexagon 21 Internal hexagon 22 Ball bearing 30 Ball pocket, recess 31 First switching cam 32 Second switching cam 33 Outfeed track 34 Freewheel track 35 Cam track 36 Branch / outlet 37 Guide 40 Sliding ring 41 Claw 42 Opening for sensor 43 Freewheel pawl ring 44 Freewheel pawl 45 Face of first guide ring 46 Freewheel tooth 47 Wave spring 48 Housing-fixed ring 49 Cylindrical section 50 Recess 51 Guide pin 52 Groove in freewheel pawl ring 53 Groove in housing-fixed ring

Claims

1. Torque-dependently releasable disconnect coupling (1) for an electric hand-held power tool, in particular for a screwdriver, to selectively transmit a torque from a drive shaft (2) to an output shaft (3) that is coaxial with respect to the drive shaft (2), with a cam ring (7) that is rotatably fixedly connectable to the drive shaft (2) or to the output shaft (3); with an axially non-displaceable first guide ring (8) that is rotatably fixedly connectable to the other of the drive shaft (2) and the output shaft (3); wherein the disconnect coupling (2) can be brought from a first switching position, in which the cam ring (7) is connected in a torque-transmitting manner with the first guide ring (8) in a first rotational direction, in particular clockwise in the axial direction viewed from the drive shaft (2) toward the output shaft (3), into a second switching position in which the cam ring (7) is freely rotatable with respect to the first guide ring (8), and with at least one switching element (11), in particular a ball, that is guided by the first guide ring (8) in the circumferential direction and / or in the radial direction and with a second guide ring (9), the cam ring (7) and the second guide ring (9) being axially pretensioned against one another and accommodate the at least one switching element (11) axially between them, wherein the cam ring (7) is designed such that when the disconnect coupling (1) is in the first switching position, the at least one switching element (11) is deflected relatively to the cam ring (7) against the action of the pretensioning in the axial direction, when a first release torque that acts in the first rotational direction is exceeded, whereby the disconnect coupling (1) is brought into the second switching position.

2. Disconnect coupling (1) according to claim 1, characterized in that the cam ring (7) comprises: - at least one depression (30), in particular a ball pocket, in which the at least one switching element (11) is accommodated in the first switching position, wherein the at least one depression (30) forms a first switching cam (31) against which the at least one switching element (11) rests in the first switching position; - a freewheeling track (34) closed in the circumferential direction, on which the at least one switching element (11) can orbit in the second switching position; - and at least one discharge track (33) that connects the at least one depression (30) and the freewheeling track (34) and on which the at least one switching element (11) can move from the at least one depression (30) to the freewheeling track (34) and vice versa, wherein, when the first release torque is exceeded, the at least one switching element (11) is deflectable in the axial direction and the disconnect coupling (1) can be brought into the second switching position by moving the at least one switching element (11) from the at least one depression (30) via the at least one discharge track (33) into the freewheeling track (34).

3. Disconnect coupling (1) according to claim 2, characterized in that the axial level of the at least one discharge track (33) rises from the depression (30) in the direction of the freewheeling track (34) and is always lower than or at the same height as the axial level of the freewheeling track (34).

4. Disconnect coupling (1) according to one of the preceding claims, characterized in that the first guide ring (8) is designed as a cage ring having at least one through opening (10), and the at least one switching element (11) is accommodated in the at least one through opening (10).

5. Disconnect coupling (1) according to claim 4, characterized in that the at least one through opening (10) has an elongated, in particular an elongated straight, shape, whose direction of extension is inclined with respect to a radial direction.

6. Disconnect coupling (1) according to one of claims 2 to 5, characterized in that the at least one depression (30) inside the cam ring (7) is arranged in a manner spaced apart from the outer circumference of the cam ring (7).

7. Disconnect coupling (1) according to one of claims 2 to 6, characterized in that the freewheeling track (34) has a constant axial level.

8. Disconnect coupling (1) according to one of claims 2 to 7, characterized in that the at least one discharge track (33) has, at least partially, the shape of a logarithmic spiral.

9. Disconnect coupling (1) according to one of the preceding claims, characterized in that the disconnect coupling (1) can be brought from a third switching position, in which the cam ring (7) is connected in a torque-transmitting manner with the first guide ring (8) in a second rotational direction opposite to the first rotational direction, in particular counterclockwise in the axial direction viewed from the drive shaft (2) toward the output shaft (3), into a fourth switching position in which the cam ring (7) is freely rotatable with respect to the first guide ring (8), and wherein the cam ring (7) is designed such that when the disconnect coupling (1) is in the third switching position, the at least one switching element (11) is deflected relatively to the cam ring (7) against the action of the pretensioning in the axial direction, when a second release torque that acts in the second rotational direction is exceeded, whereby the disconnect coupling (1) is brought into the fourth switching position.

10. Disconnect coupling (1) according to claim 2 and according to claim 9, characterized in that in the third switching position, the at least one switching element (11) is accommodated in the at least one depression (30), wherein the at least one depression (30) forms a second switching cam (32) against which the at least one switching element (11) rests in the third switching position, wherein the cam ring (7) further has a cam track (35) that is largely closed in the circumferential direction and is interrupted only by the at least one depression (30), on which the at least one switching element (11) can at least sectionwise orbit in the fourth switching position, wherein the at least one switching element (11) is deflectable in the axial direction when the second release torque is exceeded, and the disconnect coupling (1) can be brought into the fourth switching position by moving the at least one switching element (11) from the at least one depression (30) into the cam track (35).

11. Disconnect coupling (1) according to one of the preceding claims, characterized in that the disconnect coupling (1) has a freewheel (43-46) that can be opened and closed, and which is configured to be supported at a housing of the electric hand-held power tool, and which in the closed state allows a rotation of the output shaft (3) in the first rotational direction and blocks a rotation of the output shaft (3) in the second rotational direction, and in the open state does not affect the rotatability of the output shaft (3).

12. Disconnect coupling (1) according to claim 11, characterized in that the freewheel (43-46) is a ratchet-type freewheel in which at least one freewheel ratchet (44) engages with at least one freewheel tooth (46), wherein the at least one freewheel ratchet (44) is arranged on an axially displaceable, non-rotatable freewheel ratchet ring (43) that is axially pretensioned against the at least one freewheel tooth (46), and the at least one freewheel tooth (46) is arranged at an end-face side (45) of the first guide ring (8).

13. Disconnect coupling (1) according to claim 12, characterized in that the freewheel (43-46) can be closed and opened by an axial displacement of the freewheel ratchet ring (43), which is achieved by an axial displacement of the second guide ring (9).

14. Disconnect coupling (1) according to one of claims 12 and 13, characterized in that the cam ring (7) and the first guide ring (8) are arranged axially between the freewheel ratchet ring (43) and the second guide ring (9) and that the second guide ring (9) or a component that is connected to the second guide ring (9) and is axially non-displaceable with respect to the second guide ring (9) axially overlaps the cam ring (7) and the first guide ring (8).

15. Electric hand-held power tool, in particular a screwdriver, with a disconnect coupling (1) according to one of the preceding claims.