Cut-off clutch

Abstract

The invention relates to a torque-dependent actuatable disconnect clutch for an electric hand-held power tool, in particular for a screwdriver, for selectively transmitting a torque from a drive shaft to an output shaft coaxial to the drive shaft, comprising: a cam ring; a first guide ring which is non-axially displaceable and which guides a switching element, in particular a ball; and a second guide ring, wherein the cam ring and the second guide ring are axially pre-tensioned relative to each other and axially receive the switching element therebetween. The disconnect clutch can be placed from a first switching position, in which no torque is transmitted, into a second switching position, in which torque is transmitted. When a first trigger torque is exceeded in the first switching position, the switching element is offset relative to the cam ring against the prestressing force in the axial direction, whereby the disconnect clutch is placed in the second switching position. As a result, a disconnect clutch which is reliably disengaged when a first trigger torque is exceeded and which is robust and easy to form is provided.

Description

Technical Field

[0001] The invention relates to a torque-activated shut-off clutch for an electric handheld power tool, in particular for a screwdriver, which serves to selectively transmit torque from a drive shaft to an output shaft coaxial with the drive shaft, and to a method for operating an electric handheld power tool having such a shut-off clutch.

[0002] The present invention is described below using the example of a screwdriver. In particular, the present invention is intended for use with an industrial screwdriver. However, this should not be construed as restrictive. The present invention can also be used in other electric handheld power tools, such as drilling machines or grinders. Background Art

[0003] The screwdrivers considered here, also known as battery screwdrivers, are used in particular for industrial mass screw connections, for example in the production of automobiles.

[0004] For screw connections, particularly those in the industrial sector, a target tightening torque is often predefined, with which the screw connection should be tightened. During the creation of the screw connection, the tightening torque increases. Therefore, there is a need to interrupt the torque transmission in the screwdriver and, in particular, to switch off the screwdriver's motor when the target tightening torque is reached.

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

[0006] Such a disconnect clutch is known, for example, from EP 3361114 B1. Here, the disconnect clutch comprises a first clutch element and a second clutch element, which cooperate to transmit torque, wherein at least one of the two clutch elements is movable relative to the other and is prestressed by a spring element. The two clutch elements are coupled in a form-locking manner via at least one ball, thereby enabling torque to be transmitted between the two clutch elements. Furthermore, at least one clutch element comprises a cam element for each ball as a form-locking element. If the torque reaches a certain value, the balls, due to the circumferential force acting on them, begin to roll on the cam element, which has an inclination of less than 90 degrees (relative to the direction of the circumferential force). In this way, the clutch is released or "disconnected" when this torque is exceeded.

[0007] Another type of cut-off clutch is known from DE 102020130665 A1. The two clutch elements here are a cam ring and a switching ring, which are also axially prestressed relative to one another and coupled in a form-locking manner via balls. The cam ring has a circumferentially closed cam track with at least one switching cam, against which the ball abuts when the cut-off clutch is closed. When the trigger torque is exceeded, the ball is guided into the freewheeling track formed in the cam ring, so that torque can no longer be transmitted between the two clutch elements. Summary of the Invention

[0008] The object of the present invention is to further improve a shut-off clutch for an electric handheld power tool and to specify a method for operating an electric handheld power tool having such a shut-off clutch.

[0009] This object is achieved by a shut-off clutch according to claim 1, an electric handheld power tool having such a shut-off clutch according to claim 15, and by a corresponding method for operating the electric handheld power tool. Advantageous embodiments of the invention are contained in the dependent claims.

[0010] The torque-dependently triggerable shut-off clutch according to the invention for an electric handheld power tool, in particular for a screwdriver, serves to selectively transmit torque from a drive shaft to an output shaft coaxial with the drive shaft, the shut-off clutch comprising:

[0011] a cam ring which can be connected to the drive shaft or to the output shaft in a rotationally fixed manner; and

[0012] A first axially immovable guide ring, which can be connected to the other of the drive shaft and the output shaft in a rotationally fixed manner.

[0013] The shut-off clutch can be moved from a first switching position into a second switching position, wherein in the first switching position the cam ring is connected to the first guide ring in a clockwise manner in a first rotational direction, in particular in an axial direction, as viewed from the drive shaft toward the output shaft, in a torque-transmitting manner, and wherein in the second switching position the cam ring can rotate freely relative to the first guide ring.

[0014] Furthermore, the shut-off clutch according to the invention has:

[0015] at least one switching element, in particular a ball, which is guided by a first guide ring in the circumferential direction and / or in the radial direction, and;

[0016] A second guide ring, wherein the cam ring and the second guide ring are axially prestressed relative to one another and receive at least one shift element axially between them.

[0017] The cam ring is designed so that when the cut-off clutch is in the first shift position, at least one shift element is displaced relative to the cam ring in the axial direction against the effect of the prestress when a first triggering torque acting in the first rotational direction is exceeded, whereby the cut-off clutch is placed in the second shift position.

[0018] This provides a cut-off clutch that is robust and easily constructed and reliably opens when a first release torque is exceeded, thereby achieving the object of improving the cut-off clutch.

[0019] The fact that at least one switching element is accommodated between a cam ring and a second guide ring, which are prestressed axially relative to one another, 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, results in the following result: the movement of the at least one switching element is always controlled in all directions and the clutch cannot therefore have an undefined state.

[0020] Since the axial prestress acting on the at least one shifting element is generated only between the cam ring and the second guide ring, and the first guide ring is not involved, the first guide ring can be arranged according to the invention in an axially immovable manner. As a result, the rotationally fixed connection between the first guide ring and the drive shaft or output shaft can be achieved more easily by means of a rigid or even integral connection than if the first guide ring had to be axially movable.

[0021] Accordingly, it is preferred that the cam ring is also not axially displaceable, since a rotationally fixed connection between the cam ring and the drive shaft or output shaft can then be achieved more easily than if the cam ring were axially displaceable. Consequently, it is preferred that the second guide ring be axially displaceable, in order to thereby achieve an axial prestress between the cam ring and the second guide ring and a deflection of the at least one shifting element opposite to this prestress. The second guide ring, however, does not participate in the transmission of torque from the drive shaft to the output shaft and therefore does not require a rotationally fixed connection to one of these shafts.

[0022] The disconnection clutch according to the present invention particularly supports the following first application: When establishing a screw connection, particularly consisting of an externally threaded screw and an internally threaded counterpart, preferably a fastening section, particularly an opening, during right-hand rotation of a handheld power tool, the disconnection clutch should be disengaged once a target tightening torque for the screw connection has been reached. In this case, the first triggering torque should therefore correspond to this target tightening torque. Thus, the first application is to protect the screw connection against excessive tension and thereby prevent possible damage to the screw or counterpart.

[0023] In a preferred embodiment of the present invention, the cam ring has:

[0024] at least one recess, in particular a ball recess, in which in the first switching position the at least one switching element is received, 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,

[0025] a freewheel track which is closed in the circumferential direction and on which the at least one shift element can pivot in the second shift position, and

[0026] At least one lead-out track, which connects the at least one recess to the freewheel track and on which at least one shift element can be moved from the at least one recess to the freewheel track and vice versa.

[0027] The one-way clutch track and the at least one lead-out track are preferably formed by corresponding elongated recesses in the surface of the cam ring, the recesses preferably extending in a plane perpendicular to the axial direction. The one-way clutch track and the at least one lead-out track thus preferably form grooves in the surface of the cam ring, the grooves further preferably having a circular segment-shaped cross section.

[0028] Here, when a first triggering torque is exceeded, at least one shift element can be deflected in the axial direction and the shut-off clutch can be placed in the second shift position by moving the at least one shift element from the at least one recess via the at least one lead-out track into the freewheeling track.

[0029] In this way, the first and second switching positions of the cut-off clutch can be easily and reliably defined by the position of the at least one shift element in the at least one recess or in the freewheeling track. Furthermore, due to the freewheeling track being closed in the circumferential direction, the at least one shift element can be pivoted there for any length of time, whereby the cut-off clutch can remain in the second switching position and thus in the disconnected state for any length of time.

[0030] In a preferred variant of the last-described embodiment of the invention, the axial level of the at least one lead-out track rises from the recess in the direction of the freewheel track and is always lower than or equal to the axial level of the freewheel track.

[0031] The axial level is defined here as the depth in the surface of the cam ring, ie a lower axial level means a lower recess in the surface of the cam ring.

[0032] To ensure a reliable transition of the shifting element from the freewheel track into the lead-out track, the freewheel track and the at least one lead-out track preferably have different levels in the axial direction. While the freewheel track preferably has a constant level, the at least one lead-out track preferably rises continuously, starting from a first shifting cam in at least one recess in the cam ring, until it reaches the level of the freewheel track at the junction or track junction of the two tracks. The freewheel track and the at least one lead-out track preferably have the same radius or shape and transition into each other in a "smooth" manner.

[0033] Due to the different axial levels and their arrangement of the one-way clutch track and the at least one lead-out track, a stepped transition preferably occurs between the two tracks, which is arranged transversely to the direction of travel of the tracks. This stepped transition preferably forms a guide. This ensures that the shifting element can only be shifted from the at least one lead-out track into the one-way clutch track and vice versa at the track junction between the one-way clutch track and the at least one lead-out track.

[0034] The aforementioned guide at the transition between at least one lead-out track and the freewheeling track can be particularly advantageous if the cut-off clutch has more than one shifting element and a lead-out track for each shifting element. The guide ensures that all shifting elements used switch between the freewheeling track and a corresponding one of the lead-out tracks at the same time at the corresponding track junction between them. This prevents a first shifting element from switching into one of the lead-out tracks while a second shifting element is still in the freewheeling track when the direction of rotation changes.

[0035] In another preferred embodiment of the invention, an axial displacement of the cam ring and / or the second guide ring can be caused by an axial deflection of at least one shift element due to the first triggering torque, and the shut-off clutch also has a sensor that is designed to detect this displacement.

[0036] The detection of the axial movement of the cam ring and / or the second guide ring can advantageously be used to identify the second switching position of the cut-off clutch and thus its disengaged state. Subsequently, during operation of a handheld power tool having a cut-off clutch according to the present invention, a motor control for a drive motor of the handheld power tool can trigger a change in the direction of rotation of the motor, whereby at least one shift element is returned from the freewheel track via at least one lead-out track into at least one recess, whereby the cut-off clutch returns to the first switching position and is reclosed.

[0037] In another preferred embodiment of the present invention, the first guide ring is designed as a cage ring having at least one through-hole, and the at least one switching element is received in the at least one through-hole.

[0038] Due to the construction of the first guide ring as a retaining ring, the receiving chamber for at least one switching element is sealed relative to the environment, in particular in the radial direction, so that the at least one switching element cannot leave the first guide ring under the action of centrifugal force when the clutch is disconnected and thus may be "lost" inside the housing of the handheld power tool.

[0039] In a variant of the last-described embodiment of the invention, at least one through-hole has an elongated, in particular straight, shape, the direction of extension of which is inclined relative to the radial direction. Alternatively, the through-hole can have a shape that deviates from a straight shape, for example a slightly curved shape.

[0040] The inclination of the extension direction of the at least one through-hole in the first guide ring relative to the radial direction facilitates radial movement of the at least one shifting element when the cut-off clutch is shifted from the first shift position to the second shift position, wherein the at least one shifting element moves radially inward. Due to the inclination of the extension direction of the at least one through-hole relative to the radial direction, the at least one shifting element can "slide down" on the inner wall of the at least one through-hole during this movement, as if on an inclined wall, thereby reducing friction and preventing self-locking between the at least one shifting element and the first guide ring.

[0041] In another variant of the last-described embodiment of the invention, the first guide ring is arranged axially between the cam ring and the second guide ring, and the at least one switching element protrudes axially on both sides beyond the edge of the at least one through-opening.

[0042] By arranging the first guide ring axially between the cam ring and the second guide ring, forced guidance of at least one switching element in all directions, i.e., axially between the cam ring and the second guide ring and radially and / or along the circumferential direction, is achieved by the first guide ring.

[0043] Furthermore, the axial projection of at least one shifting element beyond the side surface of the first guide ring or beyond at least one through-hole in the first guide ring ensures that the second guide ring can always come into axial contact with the at least one shifting 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 the side surface of the first guide ring. Similarly, it is ensured that the cam ring can always come into axial contact with the at least one shifting element without colliding with the edge of the at least one through-hole in the first guide ring. The axial projections of the at least one shifting element on both sides of the first guide ring are preferably arranged such that, in every axial position of the at least one shifting element, the shifting element lies in a recess in the cam ring or in the at least one through-hole in the first guide ring.

[0044] In a variant of the embodiment of the present invention having at least one recess in the cam ring, the at least one recess is arranged inside the cam ring. This means that the recess, preferably in the form of a recess or a ball groove, is arranged spaced apart from the outer periphery of the cam ring. Preferably, the outer periphery of the cam ring in the region of the recess is higher than the recess, so that the recess is closed radially outward.

[0045] Similar to the case where the first guide ring is designed as a cage ring, this can have the advantage that at least one switching element cannot leave the cam ring under the action of centrifugal force when the clutch is deactivated and thus could be "lost" inside the housing of the handheld power tool.

[0046] In one of the last-described variants of the invention, the at least one recess has an elongated shape, transitions into the at least one lead-out track at a first end, and has a lower axial level than the at least one lead-out track. The transition of the recess into the lead-out track forms a first switching cam.

[0047] This design of the at least one recess represents a simple possibility for forming the first shift cam in the recess in the cam ring and thereby allowing the at least one shift element to transition directly into the at least one output track after the first shift cam has been overcome. The axial level of the at least one recess, which is lower than the axial level of the at least one output track, simultaneously brings about the desired axial deflection of the at least one shift element when the first shift cam is overcome.

[0048] In one of the last-described variants of the invention, the transition from the at least one recess into the at least one lead-out track at the first end of the at least one recess is essentially smooth when viewed along the extension direction of the at least one recess and the at least one lead-out track.

[0049] This can result in a uniform and—apart from the jerks caused by running over the shift cam—smooth movement of the at least one shift element on its way from the at least one recess into the at least one output track.

[0050] In a variant of the embodiment of the invention having at least one recess, one freewheel track and at least one derailment track in the cam ring, the freewheel track has a constant axial level.

[0051] This allows for a particularly uniform movement of the at least one shifting element in the second shifting state. This results in a low-wear, low-vibration, and / or low-noise shifting process. Furthermore, the constant axial level of the freewheel track prevents any further axial deflection of the at least one shifting element and the associated axial movement of the cam ring and / or the second guide ring, thereby enabling reliable detection of the transition from the first to the second shifting position, thereby also achieving the goal of improving the cut-off clutch.

[0052] In another variant of the embodiment of the invention having at least one recess, one freewheel track and at least one lead-out track in the cam ring, the at least one lead-out track at least partially has the shape of a logarithmic spiral.

[0053] This can also lead to a uniform and smooth movement of the at least one shifting element radially inwards on the at least one output track.

[0054] In another preferred embodiment of the present invention, the shut-off clutch can be placed from the third switching position into a fourth switching position, wherein in the third switching position the cam ring is connected to the first guide ring in a torque-transmitting manner counterclockwise along a second rotational direction opposite to the first rotational direction, in particular along an axial direction as seen from the drive shaft toward the output shaft, and wherein in the fourth switching position the cam ring can rotate freely relative to the first guide ring.

[0055] Here, the cam ring is designed so that when the cut-off clutch is in the third shift position, at least one shift element is displaced relative to the cam ring in the axial direction against the effect of the prestress when a second trigger torque acting in the second rotational direction is exceeded, whereby the cut-off clutch is placed in the fourth shift position.

[0056] This provides a cut-off clutch that is robust and easily constructed and that reliably opens when the second release torque is exceeded.

[0057] This embodiment of the disconnect clutch according to the present invention particularly supports the following second application scenario: when loosening a screw connection during counterclockwise rotation of a handheld power tool, it may be necessary for the locked screw connection to require a torque greater than the maximum motor torque for the release. Operating the handheld power tool at such a high torque could damage the motor. Therefore, the disconnect clutch should be disengaged before the maximum motor torque is reached. In this case, the second triggering torque should therefore be slightly less than the maximum motor torque. This second application scenario thus protects the handheld power tool's motor from overload and damage.

[0058] In a preferred variant of the last-described embodiment of the invention, in which at least one recess is additionally provided in the cam ring, 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 abuts in the third switching position.

[0059] The cam ring furthermore has a cam track which is largely closed in the circumferential direction and is interrupted only by at least one recess, and on which the at least one switching element can at least partially pivot in the fourth switching position.

[0060] Furthermore, when a second triggering torque is exceeded, the at least one shift element can be deflected in the axial direction and the shut-off clutch can be placed in a fourth shift position by the at least one shift element being moved from the at least one recess into the cam track.

[0061] This design of the cam ring essentially achieves the same advantages as those described above for the first and second switching positions. This means that the third and fourth switching positions of the clutch can be easily and reliably defined by the position of the at least one shifting element in the at least one recess or cam track. However, in contrast to the second shifting position, the fourth shifting position is only held until the at least one shifting element drops from the cam track into the next recess. However, the duration of this movement is sufficient to detect the fourth shifting position and react to it.

[0062] In a preferred variant of the last-described embodiment of the invention, 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, wherein the second switching cam is formed by this transition.

[0063] This can produce corresponding advantages, as in the variant described above, in which at least one recess transitions into at least one lead-out track at a first end and has a lower axial level than the at least one lead-out track, wherein the first switching cam is formed by this transition.

[0064] Preferably, the second end of at least one recess lies opposite such a first end with respect to its elongated shape.

[0065] In another preferred variant of the last-described embodiment of the invention, an axial displacement of the cam ring and / or the second guide ring can be caused by an axial offset of at least one switching element due to a second triggering torque, and the cut-off clutch also has a sensor that is designed to detect this displacement.

[0066] This can be used analogously to the above for the second shift position to detect the fourth shift position of the cut-off clutch and thus its disengaged state. However, it is not necessary to reverse the direction of rotation of the motor immediately after this detection, since in this case at least one shift element remains in the cam track and can also be returned in the same direction of rotation during continued motor operation into the recess, wherein this recess is then followed by a subsequent recess in the circumferential direction, and thus the cut-off clutch can also be returned to the third shift position.

[0067] Of course, 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 movement of the cam ring and / or the second guide ring is detected.

[0068] In a preferred variant of the corresponding variants of the present invention (in which the first and second switching cams are respectively formed by a transition at the first end or the second end of at least one recess), the inner wall of at least one recess at its second end is steeper than the inner wall of at least one recess at its first end, so that the second triggering torque is greater than the first triggering torque.

[0069] The described relationship that the steeper the transition at the respective end of the at least one recess, the greater the triggering torque is, arises directly from the aforementioned interaction of the at least one shifting element with the respective inner wall ("ramp") of the at least one recess in the sense of a wedge mechanism. The fact that the second triggering torque is greater than the first triggering torque can be advantageous because the maximum motor torque (to which the second triggering torque should be set) is generally greater than the target tightening torque of the screw connection, to which the first triggering torque should be set.

[0070] In another preferred variant of the last-described embodiment of the invention, the cam track has a constant axial level except in the region of the at least one recess.

[0071] This allows the same advantages as in a corresponding embodiment with a constant axial level of the freewheel track to be achieved, ie in this case the transition from the third to the fourth shift position can be reliably detected.

[0072] In another preferred embodiment of the present invention, the disconnecting clutch has a one-way clutch that can be disconnected and closed, which is configured to be supported on the housing of the electric hand tool and which allows the output shaft to rotate in a first rotational direction and prevents the output shaft from rotating in a second rotational direction in a closed (activated) state and does not affect the rotatability of the output shaft in a disconnected (deactivated) state.

[0073] A freewheel clutch having these functions is advantageous when, in the second switching position, the motor's direction of rotation 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 lead-out track into the at least one recess. In this case, the output shaft must be prevented from rotating along with it, as otherwise the required relative rotation between the drive shaft and the output shaft would not be possible. Therefore, in this case, the freewheel clutch can be closed so that it blocks the output shaft from rotating in the second direction of rotation, thereby preventing the output shaft from rotating along with it in the second direction of rotation.

[0074] In a preferred variant of the last-described embodiment of the invention, the freewheel is a pawl-type freewheel clutch, in which at least one freewheel pawl engages in at least one freewheel tooth. The at least one freewheel pawl is arranged on an axially displaceable, non-rotatable freewheel pawl ring that is axially prestressed toward the at least one freewheel tooth, and the at least one freewheel tooth is arranged on the end face of the first guide ring.

[0075] The design as a ratchet-type freewheel is a common structural design of a freewheel and can be easily implemented. In particular, using the first guide ring for accommodating at least one freewheel tooth can be advantageous because no additional components are required for arranging the freewheel tooth.

[0076] In a preferred variant of the above-described variant of the invention, the freewheel can be closed and opened by an axial displacement of the freewheel pawl ring, which can be brought about by an axial displacement of the second guide ring.

[0077] 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 movement of the second guide ring, it is also advantageous to cause the freewheel to be closed and opened by this movement. Since the freewheel pawl ring is axially movable, it is also advantageous to cause the freewheel to be closed and opened by such an axial movement of the freewheel pawl ring. In this way, the existing movement options of the involved components are used for closing and opening the freewheel.

[0078] The axial movement of the freewheel pawl ring is induced by the axial movement of the second guide ring, which can be direct or indirect. In the case of direct axial movement, the freewheel pawl ring can be directly supported in the axial direction on the second guide ring. In the case of indirect axial movement, at least one additional force-transmitting component can also be arranged between the second guide ring and the freewheel pawl ring, in particular a component that is connected to the second guide ring and axially movable therewith but is not itself rotatable.

[0079] In a preferred variant of the above-described variant of the present invention, the cam ring and the first guide ring are axially arranged between the one-way clutch pawl ring and the second guide ring, and the second guide ring or a component connected to the second guide ring and not axially movable relative to the second guide ring axially overlaps the cam ring and the first guide ring.

[0080] If the freewheel is to be closed and opened by axially moving the second guide ring and the resulting axial movement 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 arranged axially between them, this can be achieved in a simple manner by having the second guide ring or a component connected to the second guide ring and immovable axially relative to the second guide ring axially overlap the two latter components. This also includes the case where the axial movement of the freewheel pawl ring is indirectly caused by axial movement of the second guide ring and another component that transmits force and is connected to the second guide ring but immovable axially relative to the second guide ring axially overlaps the cam ring and the first guide ring.

[0081] In another preferred variant of the last-described embodiment of the invention, the freewheel is open in the first shift position and closed in the second shift position.

[0082] This corresponds to the requirement that the freewheel should be engaged if the direction of rotation of the motor is to be reversed from the first to the second direction of rotation after the transition from the first to the second shift position in order to prevent the output shaft from rotating in the second direction of rotation.

[0083] Since, in contrast, no reversal of the direction of rotation of the motor is required after the transition from the third to the fourth shift position as described above, it is irrelevant in this case whether the freewheel is closed or open.

[0084] Furthermore, the present invention relates to an electric handheld power tool, in particular a screwdriver, having a disconnect clutch according to the present invention. Thus, the two applications described above can be realized in a simple and reliable manner for clockwise or counterclockwise rotation of the motor of the handheld power tool.

[0085] Furthermore, the present invention relates to a method for operating an electric handheld power tool, in particular a screwdriver, having a shutoff clutch according to the invention, comprising the following steps:

[0086] - driving the drive shaft in a first direction of rotation while the disconnect clutch is in the first switching position,

[0087] - stopping the rotation of the drive shaft when a torque exceeding a first trigger torque acts in a first direction of rotation, wherein the shut-off clutch is placed in the second shift position due to the exceeding of the first trigger torque,

[0088] The drive shaft is driven in the second direction of rotation, whereby the shut-off clutch is placed back in the first shift position.

[0089] This corresponds to the first application case already described in detail above, in which the shut-off clutch is to be opened and then closed again as soon as the target tightening torque of the screw connection to be produced is reached.

[0090] Furthermore, the present invention relates to a method for operating an electric handheld power tool, in particular a screwdriver, having a shut-off clutch which can also be placed into a third and a fourth switching position, the method comprising the following steps:

[0091] - driving the drive shaft in the second direction of rotation while the disconnect clutch is in the third switching position,

[0092] - when a torque exceeding the second triggering torque acts in the second rotational direction, the drive shaft is further driven in the second rotational direction, wherein the shut-off clutch is placed in the fourth shift position due to the exceeding of the second triggering torque,

[0093] The drive shaft is driven further in the second direction of rotation, thereby placing the shut-off clutch in the third shift position again.

[0094] This corresponds to the second application case, which has also been described in detail above, in which the cut-off clutch should be opened before the maximum motor torque is reached in order to protect the motor from overload, and then closed again. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Further advantages, features and possible applications of the present invention are apparent from the following description in conjunction with the accompanying drawings.

[0096] Figure 1 Shows a side view of a cut-off clutch according to the present invention;

[0097] Figure 2 Shown in accordance with Figure 1 Cross-section of the cut-off clutch;

[0098] Figure 3 Shown in accordance with Figure 1 Exploded view of the cut-off clutch;

[0099] Figure 4 Shown in accordance with Figure 1 A member forming an engagement mechanism of a cut-off clutch;

[0100] Figure 5 Shown in accordance with Figure 1 an end side of a cam ring of a cut-off clutch;

[0101] Figure 6 Shown in accordance with Figure 1 A component that forms a reset mechanism for the disconnect clutch. DETAILED DESCRIPTION

[0102] The invention is described in detail below with reference to a single embodiment of the disconnect clutch 1 according to the invention. Figure 1 、 2 and 3 in a different view, namely as a side view ( Figure 1 ),profile( Figure 2 ) and exploded view ( Figure 3 ) shows the entire disconnect clutch 1. Figure 4 、 5 6 and 7 show the individual components or subassemblies of the cut-off clutch 1, that is, the engagement mechanism that causes the cut-off clutch 1 to be opened and closed ( Figure 4 ), the end face of the cam ring 7 with various cutouts 30 to 35 for the balls 11 ( Figure 5 ) and a reset mechanism for closing the one-way clutch when the cut-off clutch 1 is disconnected ( Figure 6).

[0103] The disconnect clutch 1 is designed to be installed in an electric rotary handheld power tool (not shown), in particular a screwdriver such as is used in industrial production. The disconnect clutch 1 is arranged in the power train of the handheld power tool, particularly for screwdriving tools such as screwdriver blades or hexagon socket or hexagon socket tools, between the drive motor and the tool holder. However, the disconnect clutch 1 according to the present invention can also be used in other handheld power tools.

[0104] The components of the disconnect clutch 1 are essentially all arranged coaxially about an axis, which simultaneously forms the axis of rotation of the rotatable components. At the same time, the disconnect clutch 1 is supported on the housing (not shown) of the handheld power tool by a ring 48 fixed to the housing and is directly or indirectly rigidly connected to the housing.

[0105] The disconnect clutch 1 has a drive shaft 2, the outer end of which is designed, for example, in the form of an external hexagon 20. The external hexagon 20 is provided for a permanent, form-locking, and rotationally fixed connection with a drive motor (not shown) of a handheld power tool. Coaxially with the drive shaft 2, the disconnect clutch 1 has an output shaft 3, on the outer end of which a hexagon socket 21 is formed. The hexagon socket 21 is provided for receiving a replaceable tool, in particular a threaded insert of any type (not shown), in a form-locking, rotationally fixed manner. The tool is preferably inserted manually into the hexagon socket 21 and is preferably held in place by friction, by a latching mechanism, or magnetically.

[0106] The drive shaft 2 and the output shaft 3 are rotatably supported relative to each other via ball bearings 17. When the cut-off clutch 1 is installed, the balls of the ball bearings 17 are inserted individually through radial bores in the outer bearing sleeve in the drive shaft 2, and these bores are then closed by plugs 18.

[0107] The disconnect clutch 1 has the task 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 handheld power tool is in operation in the closed state. As soon as the torque transmitted from the drive shaft 2 to the output shaft 3 exceeds a specific adjustable release torque, the disconnect clutch 1 is to be opened so that no torque can be transmitted from the drive shaft 2 to the output shaft 3.

[0108] In particular, the disengagement of the cutting clutch 1 when the release torque is exceeded should support the two application cases described above:

[0109] When establishing a screw connection during clockwise rotation of the handheld power tool, the disconnect clutch 1 should be disengaged as soon as the target tightening torque of the screw connection is reached (first application case). When loosening a screw connection during counterclockwise rotation of the handheld power tool, the disconnect clutch 1 should be disengaged if the required loosening torque exceeds the maximum motor torque in order to protect the motor of the handheld power tool from overload (second application case).

[0110] Since the two applications are different, the respective required triggering torques may also be different. Since, in particular in the first application, the target tightening torques differ from one screw connection to another, the triggering torque should be preselectable by the user of the handheld power tool in this case.

[0111] To achieve the desired disengagement of the cut-off clutch 1 during clockwise or counterclockwise rotation when the corresponding release torque is exceeded, the drive shaft 2 is connected to the cam ring 7 in a rotationally fixed manner—in this embodiment, integrally. Various recesses with different axial levels are formed in the end face of the cam ring 7 that faces the output shaft 3 in the axial direction. These recesses are designed so that a plurality of balls 11, in this embodiment three, are accommodated therein and can move therein substantially in the circumferential direction. The precise arrangement and functioning of the recesses in the cam ring 7 will be described in detail below.

[0112] For each ball 11, at least one location is provided in the recess in the cam ring 7 where the axial level of the recess changes in a step-like manner. In other words, the recess has an axial step at this location. However, the "vertical" wall of the step does not extend precisely in the axial direction, but rather at an angle relative to the step, more precisely, such that the step forms a steep, but non-vertical, slope from a lower axial level (in the sense of the lower recess in the end face of the cam ring 7) to a higher axial level.

[0113] In the closed state of the disconnect clutch 1, the balls 11 are located in the recess on the side of the step with the lower axial level and bear against the step in such a way that, given a predetermined direction of rotation of the drive shaft 2, the step presses against the balls 11 in the circumferential direction. In this manner, in this state of the disconnect clutch 1, torque can initially be transferred from the cam ring 7 to the balls 11. The disconnect clutch 1 is then in the first shift position.

[0114] Axially adjacent to the cam ring 7 is arranged a first guide ring 8 which is connected in a rotationally fixed manner—in this exemplary embodiment, integrally—to the output shaft 3. Consequently, neither the cam ring 7 nor the first guide ring 8 can be axially moved.

[0115] The first guide ring 8 has a through-hole 10 for each ball 11, in which the portion of the ball 11 that protrudes axially beyond the cam ring 7 is guided. Each through-hole 10 is designed as a straight line, that is, as an elongated hole, and extends in the first guide ring 8 from the radially outer end to the radially inner end in a direction that is inclined relative to the radial direction. The radially outer ends of the elongated holes are spaced apart from the outer periphery of the first guide ring 8. This ensures that each ball 11 is positively guided in the elongated hole, preventing it from being lost. The axial extent of the first guide ring 8 is designed so that, in every possible position it can assume in the recess in the cam ring 7, each ball 11 rests with its maximum diameter against the inner wall of the associated through-hole 10, while 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 its through-holes 10, thus functions as 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 the output shaft 3 .

[0116] On the side of the first guide ring 8 opposite the cam ring 7, a second guide ring 9 is arranged, whose end face facing the first guide ring 8 is completely flat. The second guide ring 9 is rotatably and axially displaceably supported on the output shaft 3, preferably via a plain bearing. As will be explained in more detail below, the second guide ring 9 is prestressed axially toward the cam ring 7 so that its flat end face is pressed against the balls 11.

[0117] In this way, the ball 11 is forcibly guided in all directions, i.e., in the axial direction through the recess in the end face of the cam ring 7 and through the flat end face of the second guide ring 9, and in the radial direction and in the circumferential direction through the through-hole 10 in the first guide ring 8. This forcible guidance of the ball 11 prevents the ball 11 from moving uncontrolled during the rotation of the drive shaft 2 and the output shaft 3 and becoming lost inside the housing of the handheld power tool.

[0118] As is clear from the description thus far, in the closed state of the disconnection clutch 1, torque can be transmitted from the drive shaft 2 to the output shaft 3 via the cam ring 7, the balls 11, and the first guide ring 8. The second guide ring 9 does not participate in the torque transmission itself, but rather forms part of the axial guidance of the balls 11.

[0119] As mentioned above, when the clutch 1 is engaged, each ball 11 rests against an associated step in the recess in the end face of the cam ring 7. The step forms a steep, but not vertical, ramp, and torque can be transferred from the ramp to the ball 11 in the predetermined direction of rotation of the drive shaft 2. The surface of the ball 11 and the ramp form a wedge mechanism. Simultaneously, the ball 11 is prestressed axially toward the end face of the cam ring 7 by the second guide ring 9. This prestress is designed so that when the torque transmitted between the ramp and the ball 11 exceeds a first triggering torque, the ball 11 "rises" on the ramp due to the wedge effect and reaches the axially higher portion of the recess in the end face of the cam ring 7.

[0120] As will be explained in more detail below, this recess is arranged so that the balls 11 can move freely in the axially higher part of the recess in the circumferential direction. Consequently, in this state of the disconnect clutch 1, torque can no longer be transmitted between the cam ring 7 and the balls 11, and thus also between the drive shaft 2 and the output shaft 3. The disconnect clutch 1 is then in the second shift position and is in the disconnected state.

[0121] The ramp in the recess in the end face of the cam ring 7 thus acts as a first shifting cam 31, the point at which the ball 11 passes over said first shifting cam in a first rotational direction causing the cut-off clutch 1 to transition from the engaged state to the disengaged state. In a second rotational direction, opposite to the first, this ramp also acts as a first shifting cam 31, the point at which the ball 11 passes over said first shifting cam causing the cut-off clutch to transition from the disengaged state to the engaged state.

[0122] The end face of the cam ring 7 will now be described in detail, including the recesses therein for the balls 11. In the present exemplary embodiment, three balls 11 are provided, and the end face of the cam ring 7 has recesses for each ball 11 that are offset by 120 degrees and thus have three-fold rotational symmetry.

[0123] The recess for the ball 11 initially comprises an elongated ball groove 30, which has a lower axial level than all other recesses in the end face of the cam ring 7. The ball groove 30 extends approximately in the circumferential direction, but is slightly curved radially inwards towards one end.

[0124] At the two ends of the ball groove 30, the low axial level of the ball groove 30 is transformed into a higher axial level of the surrounding environment of the ball groove 30, and the two ends thus form a first switching cam 31 for transmitting torque to the output shaft 3 when the drive shaft 2 rotates right or a second switching cam 32 for transmitting torque to the output shaft when the drive shaft 2 rotates left.

[0125] If the first triggering torque is exceeded during a clockwise rotation of the drive shaft 2, the ball 11 passes over the first switching cam 31 as described above and enters the adjacent lead-out track 33, which spirals radially inward. The lead-out track 33 preferably has the shape of a logarithmic spiral to ensure uniform and smooth movement of the ball 11. The slight radial inward curvature of the ball groove 30 is also selected so that the ball groove 30 transitions into the lead-out track 33 in a "smooth" manner, similarly ensuring uniform and smooth movement of the ball 11.

[0126] At the same time, as the balls 11 move radially inward in the guide rails 33, they also move radially inward along the longitudinal extent of the through-holes 10 in the guide ring 8. Because the through-holes 10 are not arranged radially but rather inclined relative to the radial direction, the balls 11 can slide downward at an inclined angle on the inner surface of the through-holes 10, thereby reducing friction and preventing possible self-locking of the balls 11 as they move in the through-holes 10.

[0127] The discharge track 33 opens in the radially inner region of the end face of the cam ring 7 into a closed, circular freewheel track 34 with a constant axial level, in which the balls 11 can revolve for any length of time.

[0128] If the balls 11 are in the lead-out track 33 or in the freewheel track 34 and thus exert no mechanical resistance in the circumferential direction, torque can no longer be transmitted from the drive shaft 2 to the output shaft 3. The clutch 1 is then disconnected and thus prevented from exceeding the target tightening torque of the screw connection.

[0129] Because the lead-out track 33 and the one-way clutch track 34 have a higher axial level than the ball groove 30, the ball 11 moves in the axial direction toward the output shaft 3. As a result, the second guide ring 9, which is prestressed toward the ball 11 and the cam ring 7, is also moved in this axial direction.

[0130] The second guide ring 9 is rotatably supported relative to the slip ring 40 (whose function will be described in more detail) via a ball bearing 6, so that the slip ring 40 itself does not rotate together. The second guide ring 9 and the slip ring 40 are connected to form a unit via the ball bearing 6 and are therefore unable to move axially relative to each other and can only be displaced axially together.

[0131] The slip ring 40 has an opening 42 on its outer periphery, which can contain a position indicator, such as a permanent magnet (not shown). A corresponding sensor, such as a magnetic sensor (also not shown), is installed in the housing of the handheld power tool, which can detect the axial movement of the position indicator and thus the axial movement of the slip ring 40.

[0132] The sensor detects that the disconnect clutch 1 has switched to the disconnected state based on the axial movement of the slip ring 40 and forwards the corresponding signal to the control mechanism of the drive motor of the handheld power tool. The motor is then disconnected. After the rotational movement of the motor stops, the rotation direction of the drive shaft 2 is changed. In the one-way clutch track 34 (at the cam ring 7) Figure 5 The ball 11, which had been rotating clockwise (in the orientation shown in FIG), now rotates counterclockwise after reversing its direction of rotation and reenters one of the lead-out tracks 33 at a "branch" or track opening 36, and reenters the associated ball groove 30 at its end. The guide 37 created by the arrangement and different levels of the freewheel tracks 34 or lead-out tracks 33 ensures that the ball 11 always switches from the freewheel track 34 to the lead-out track 33 at the track opening 36. This is particularly important if the cut-off clutch 1 includes more than one ball 11. This prevents one ball 11 from being in the freewheel track 34 and the other in the lead-out track 33. This ensures reliable opening and closing of the cut-off clutch 1. The sensor detects the further axial movement of the slip ring 40 in the direction of the drive shaft 2 associated with the transition of the ball 11 into the ball groove 30, and the motor control unit then stops the motor's rotation. The cut-off clutch 1 is thus closed again.

[0133] When the drive shaft 2 rotates counterclockwise, the ball 11 abuts against the second shift cam 32 at the end of the ball groove 30 opposite the first shift cam 31, so that 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 clutch 1 is then disengaged and in the third shift position.

[0134] If the second release torque is now exceeded during a counterclockwise rotation of the drive shaft 2, the ball 11 passes over the second shifting cam 32 and enters the adjacent cam track 35. The cam track 35 runs circularly around the outer radial edge of the cam ring 7, concentrically with respect to the freewheel track 34, and is interrupted only by the ball groove 30. In this case, the cam track 35, apart from the ball groove 30, has a constant axial level that is higher than the axial level of the ball groove 30.

[0135] The ramp at the end of the ball groove 30 forming the second shifting cam 32 is preferably designed to be steeper than the ramp at the end of the ball groove 30 forming the first shifting cam 31. As a result, the second triggering torque is preferably also greater than the first triggering torque.

[0136] In the cam track 35 , the ball 11 can rotate at least as far as the next ball groove 30 , that is, within a rotational angle range of 5 to 120 degrees, without mechanical resistance exerted on it in the circumferential direction. Consequently, during this movement of the ball 11 , torque cannot be transmitted from the drive shaft 2 to the output shaft 3 . The disconnect clutch 1 is then in the fourth shift position. In this fourth shift position, the disconnect clutch 1 is also in the disengaged state and prevents the maximum motor torque from being exceeded, particularly when it is insufficient to loosen the screw connection.

[0137] In this case, when the disconnect clutch 1 is disengaged, the slip ring 40 is also displaced axially, which is again detected by the sensor. The motor control can then, for example, continue the counterclockwise rotation of the motor at a low speed until each ball 11 has settled back into its corresponding ball recess 30. Reversing the direction of rotation of the motor is unnecessary in this case. As a result, the disconnect clutch 1 is once again in the closed state. Even further operation of the motor at a low speed can be omitted, because at the latest the next time the handheld power tool is used—whether in clockwise or counterclockwise rotation—the balls 11 will have settled back into the ball recess 30, and the disconnect clutch 1 will then be in the closed state again.

[0138] The first and second actuating torques can be pre-set depending on the desired application, in particular on the target tightening torque of the screw connection to be produced, by the axial prestressing of the second guide ring 9 towards the balls 11 and the cam ring 7 .

[0139] This prestress is generated by an axially prestressed compression spring 12, which is designed as a helical spring and extends around the output shaft 3. The compression spring 12 is supported at one end on the second guide ring 9 and at the other end on a compression ring 13, which engages on its inner side with a projection (not shown) in the flattened portion 5 on the output shaft 3 ( Figure 6) and, while axially movable relative to the output shaft 3, is not rotatable. On the side of the pressure ring 13 facing away from the compression spring 12, an adjusting ring 15 is screwed onto the thread 4 of the output shaft 3. The thread 4 is preferably a left-hand thread. Multiple (six in the present embodiment) latching balls 14 are inserted at regular angular intervals into the end face of the pressure ring 13 facing the adjusting ring 15. These latching balls can engage in multiple (twelve in the present embodiment) bores 16 on the opposite end face of the adjusting ring 15, also arranged at regular angular intervals. This allows the adjusting ring 15 to be rotated against the spring force of the compression spring 12 by a specific angle (30 degrees in the present embodiment), which is perceived by the user as a single latching stage, and the adjusting ring is then screwed further onto or unscrewed from the output shaft 3. Each latching stage increases or decreases the prestressing force of the compression spring 12, and thus the first and second actuating torques. In the handheld power tool, the adjustment ring 15 is surrounded by an actuating ring (not shown), which is preferably made of non-slip plastic and can be easily adjusted by hand by an operator.

[0140] As described above, if the clutch has been disengaged during clockwise rotation of the motor due to exceeding the first release torque, the direction of rotation of the motor is briefly reversed from clockwise to counterclockwise so that the balls 11 are moved back into their ball recesses 30 by the drive shaft 2 and, therefore, the cam ring 7, due to a relative rotation to the left, i.e., counterclockwise, relative to the balls 11. The disconnecting clutch 1 is thus reclosed after disengagement. Since the balls 11 are positively guided by the first guide ring 8 and are connected to the output shaft 3 in a rotationally fixed manner, the output shaft 3 must be prevented from rotating with the drive shaft 2 during a counterclockwise rotation, since otherwise no such relative rotation would occur between the drive shaft 2 and the output shaft 3.

[0141] Co-rotation of the output shaft 3 can be prevented, for example, by ensuring that the tool remains engaged with the previously secured bolt even after the motor's direction of rotation has been reversed. However, in actual use of the handheld power tool, it cannot be guaranteed that the user will immediately engage the tool with the bolt after the target tightening torque for the bolt has been reached and the disconnect clutch 1 has been disengaged. Once the tool is disengaged from the bolt, co-rotation of the output shaft 3 is no longer precluded.

[0142] In order to reliably prevent the output shaft 3 from rotating together in any state of the disconnect clutch 1 after the direction of rotation of the motor is reversed, that is, when the motor rotates counterclockwise, the disconnect clutch 1 has a reset mechanism, which will be described below (see also Figure 6 ).

[0143] The reset mechanism is triggered by the previously described axial movement of the slip ring 40 when the cut-off clutch 1 is disconnected. Figure 2As can be seen in FIG, the slip ring 40 engages radially outwardly with the second guide ring 9, the first guide ring 8, the balls 11, and the cam ring 7 by means of a plurality (in the present embodiment, three) of claws 41 pointing toward the drive shaft 2 and distributed over the circumference of the slip ring 40. The claws 41 are supported on the radially outer region of the end face of a one-way clutch pawl ring 43, which has approximately the same diameter as the slip 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 a plurality of claws 41, the slip ring 40 can also have a circumferential, cylindrical outer circumference that is uniformly supported on the radially outer region of the end face of the one-way clutch pawl ring 43.

[0144] The one-way clutch pawl ring 43 is axially movable but not rotatable because it is axially guided by a plurality of axially arranged guide pins 51. To this end, the one-way clutch pawl ring 43 has grooves 52, which together with the guide pins 51 form an axial sliding guide. The guide pins 51 are rigidly connected to the cylindrical section 49 of the ring 48 fixed to the housing on the outer side of the ring. The guide pins 51 engage in grooves 53 in the cylindrical section 49 of the ring 48 fixed to the housing. The ring 48 fixed to the housing is rigidly connected to the housing via a plurality of recesses 50 in its circumference and projections (not shown) in the housing of the handheld power tool, thereby preventing both axial displacement and rotation. In this way, the one-way clutch pawl ring 43 is supported axially movably on the cylindrical section 49 of the ring 48 fixed to the housing, but cannot rotate due to the guidance provided by the guide pins 51.

[0145] In addition, the ring 48 fixed on the housing has the function of supporting the ball bearing 22 from the radial outside, and the drive shaft 2 is supported in the ball bearing in the radial inside. The bearing between the ring 48 fixed on the housing and the drive shaft 2 is also fixed by the anti-loosening ring 19.

[0146] Furthermore, a wave spring 47 is arranged between a flange on the ring 48 fixed to the housing, which has a larger diameter than the diameter of the cylindrical section 49, and a flange of the one-way clutch pawl ring 43, which has a diameter approximately the same as the diameter of the flange of the ring 48 fixed to the housing. This wave spring pre-tensions the one-way clutch pawl ring 43 axially in the direction of the output shaft 3. For example, other compression springs, in particular helical springs, can also be used for this purpose instead of the wave spring.

[0147] The spring force of the wave spring 47 is always smaller than the spring force of the compression spring 12 , so that the prestressing of the unit formed by the slide ring 40 and the second guide ring 9 toward the ball 11 is not canceled.

[0148] The one-way clutch pawl ring 43 has a plurality of protrusions distributed over its circumference on its end side pointing toward the first guide ring 8, which serve as the one-way clutch pawls 44 ( Figure 6 ). The end side 45 of the cylindrical flange of the first guide ring 8, which is axially overlapped with the cam ring 7 on the radial outside, has a zigzag shape when viewed in the circumferential direction. This forms a plurality of one-way clutch teeth 46, into which the one-way clutch pawl 44 can be embedded. In the disconnected state of the clutch 1, when the ball 11 is outside the ball groove 30, the one-way clutch pawl ring 43 is axially pressed against the first guide ring 8 by the elastic force of the wave spring 47. Thereafter, the one-way clutch pawl 44 can be engaged with the one-way clutch teeth 46, and the one-way clutch is in a closed state. The direction of the zigzag shape of the end side 45 of the cylindrical flange of the first guide ring 8 and the arrangement of the one-way clutch teeth 46 are selected in this way so that the first guide ring 8 and the output shaft 3 can only rotate to the right, but not to the left.

[0149] When the clutch 1 is closed, the claw 41 of the slip ring 40 overcomes the elastic force of the wave spring 47 and squeezes the one-way clutch pawl ring 43 axially away from the first guide ring 8, so that the one-way clutch pawl 44 cannot be embedded in the one-way clutch teeth 46 and the one-way clutch is disconnected and does not work.

[0150] When the disconnect clutch 1 is disengaged, the claws 41 of the slip ring 40 are not pressed against the freewheeling pawl ring 43 because the unit formed by the slip ring 40 and the second guide ring 9 is moved axially toward the output shaft 3 by the balls 11, so that the wave spring 47 presses the freewheeling pawl ring 43 axially toward the first guide ring 8 so that the freewheeling pawls 44 can engage with the freewheeling teeth 46 and the freewheeling clutch is closed. This results in the desired behavior of the freewheeling clutch, namely that it is closed only in the disconnected state of the disconnect clutch 1 (in which the direction of rotation of the motor is also reversed) and thus prevents the output shaft 3 from rotating together when the motor rotates counterclockwise.

[0151] When the cut-off clutch 1 is disengaged due to exceeding the second trigger torque during counterclockwise rotation of the motor, the one-way clutch is closed and the ball 11 is located in the cam track 35. However, this has no further effect because, as described above, the ball does not need to return from the one-way clutch track 34 to the ball groove 30 in this case, and thus, the direction of rotation of the motor does not need to be reversed, which would prevent the output shaft 3 from rotating together. The state change of the one-way clutch from the disengaged state to the engaged state has no effect when the cut-off clutch 1 is disengaged during counterclockwise rotation of the motor.

[0152] List of reference numerals:

[0153] 1. Disengage the clutch

[0154] 2 drive shaft

[0155] 3 Output shaft

[0156] 4 threads

[0157] 5 Flattening

[0158] 6 ball bearings

[0159] 7 Cam ring

[0160] 8 First guide ring

[0161] 9 Second guide ring

[0162] 10 through holes

[0163] 11 goals

[0164] 12 Compression spring

[0165] 13 Pressure Ring

[0166] 14 Lock Ball

[0167] 15 Adjustment ring

[0168] 16 Drilling

[0169] 17 ball bearings

[0170] 18 plug

[0171] 19 Anti-loosening ring

[0172] 20 external hexagon

[0173] 21 Hexagon socket

[0174] 22 ball bearings

[0175] 30 ball grooves and recesses

[0176] 31 First switching bump

[0177] 32 Second switching cam

[0178] 33 Export Track

[0179] 34 One-way clutch track

[0180] 35 Cam Track

[0181] 36 branch / railway entrance

[0182] 37 Guide

[0183] 40 slip rings

[0184] 41 claws

[0185] 42 Opening for sensor

[0186] 43 One-way clutch pawl ring

[0187] 44 One-way clutch pawl

[0188] 45 End side of the first guide ring

[0189] 46 one-way clutch teeth

[0190] 47 Wave Spring

[0191] 48 Ring fixed to the housing

[0192] 49 cylindrical sections

[0193] 50 blank space

[0194] 51 guide pin

[0195] 52 Groove in one-way clutch pawl ring

[0196] 53 Groove in the ring fixed to the housing

Claims

1. A torque-dependent, triggerable shut-off clutch (1) for an electric handheld power tool, in particular a screwdriver, for selectively transmitting torque from a drive shaft (2) to an output shaft (3) coaxial with the drive shaft (2), the shut-off clutch comprising: A cam ring (7) is provided, which can be connected to the drive shaft (2) or to the output shaft (3) in a rotationally fixed manner; A first guide ring (8) is provided which cannot be displaced axially and can be connected to the other of the drive shaft (2) and the output shaft (3) in a rotationally fixed manner. wherein the shutoff clutch (2) can be moved from a first switching position into a second switching position, wherein in the first switching position the cam ring (7) is connected to the first guide ring (8) in a clockwise manner in a first rotational direction, in particular in an axial direction, as viewed from the drive shaft (2) toward the output shaft (3), in a torque-transmitting manner, and wherein in the second switching position the cam ring (7) is freely rotatable relative to the first guide ring (8); At least one switching element (11), in particular a ball, is guided by a first guide ring (8) in the circumferential direction and / or in the radial direction; and having a second guide ring (9), wherein the cam ring (7) and the second guide ring (9) are axially prestressed relative to each other and receive the at least one switching element (11) axially therebetween, The cam ring (7) is designed so that when the cut-off clutch (1) is in the first shift position, the at least one shift element (11) is displaced relative to the cam ring (7) in the axial direction against the effect of the prestressing force when a first triggering torque acting in the first rotational direction is exceeded, thereby placing the cut-off clutch (1) in the second shift position.

2. The disconnect clutch (1) according to claim 1, characterized in that The cam ring (7) has: at least one recess (30), in particular a ball recess, in which the at least one switching element (11) is received in the first switching position, wherein a first switching cam (31) is formed by the at least one recess (30), against which the at least one switching element (11) abuts in the first switching position, a freewheel track (34) which is closed in the circumferential direction and on which the at least one shift element (11) can pivot in the second shift position; and at least one lead-out track (33), which connects at least one recess (30) to the one-way clutch track (34) and on which the at least one switching element (11) can be moved from the at least one recess (30) to the one-way clutch track (34) and vice versa, The at least one switching element (11) can be displaced in the axial direction when a first trigger torque is exceeded and the cut-off clutch (1) can be placed in a second switching position in such a manner that the at least one switching element (11) moves from at least one recess (30) via at least one output track (33) into a one-way clutch track (34).

3. The disconnect clutch (1) according to claim 2, characterized in that The axial level of the at least one lead-out track (33) increases from the recess (30) in the direction of the one-way clutch track (34) and is always lower than or equal to the axial level of the one-way clutch track (34).

4. A disconnect clutch (1) according to any one of the preceding claims, characterized in that The first guide ring (8) is designed as a cage ring having at least one through-hole (10), and the at least one switching element (11) is received in the at least one through-hole (10).

5. The disconnect clutch (1) according to claim 4, characterized in that The at least one through-hole (10) has an elongated, in particular an elongated, straight shape, the direction of extension of which is inclined with respect to the radial direction.

6. The disconnect clutch (1) according to any one of claims 2 to 5, characterized in that At least one recess (30) inside the cam ring (7) is arranged spaced apart from its outer periphery.

7. The disconnect clutch (1) according to any one of claims 2 to 6, characterized in that The one-way clutch track (34) has a constant axial level.

8. The disconnect clutch (1) according to any one of claims 2 to 7, characterized in that The at least one lead-out track (33) at least partially has the shape of a logarithmic spiral.

9. A disconnect clutch (1) according to any one of the preceding claims, characterized in that The shut-off clutch (1) can be moved from a third switching position into a fourth switching position, wherein in the third switching position the cam ring (7) is connected to the first guide ring (8) in a second rotational direction opposite to the first rotational direction, in particular in an axial direction, viewed from the drive shaft (2) toward the output shaft (3), in a counterclockwise, torque-transmitting manner, and wherein in the fourth switching position the cam ring (7) is freely rotatable relative to the first guide ring (8), The cam ring (7) is designed so that when the cut-off clutch (1) is in the third shift position, the at least one shift element (11) is displaced relative to the cam ring (7) in the axial direction against the effect of the prestress when a second triggering torque acting in the second rotational direction is exceeded, thereby placing the cut-off clutch (1) in the fourth shift position.

10. The cut-off clutch (1) according to claim 2 and claim 9, characterized in that The at least one switching element (11) is received in the at least one recess (30) in the third switching position, wherein a second switching cam (32) is formed by the at least one recess (30), against which the at least one switching element (11) abuts in the third switching position. The cam ring (7) further comprises a cam track (35) which is largely closed in the circumferential direction and is interrupted only by at least one recess (30), and on which the at least one switching element (11) can at least partially pivot in the fourth switching position. The at least one shifting element (11) can be displaced in the axial direction when a second triggering torque is exceeded and the shut-off clutch (1) can be placed in a fourth shifting position by moving the at least one shifting element (11) from at least one recess (30) into a cam track (35).

11. A cut-off clutch (1) according to any one of the preceding claims, characterized in that The disconnecting clutch (1) has a one-way clutch (43-46) which can be disconnected and closed, is designed to be supported on a housing of an electric handheld machine tool, and in a closed state allows the output shaft (3) to rotate in a first rotational direction and prevents the output shaft (3) from rotating in a second rotational direction, and does not affect the rotatability of the output shaft (3) in a disconnected state.

12. The disconnect clutch (1) according to claim 11, characterized in that The one-way clutch (43-46) is a ratchet-type one-way clutch, wherein at least one one-way clutch pawl (44) is embedded in at least one one-way clutch tooth (46), wherein the at least one one-way clutch pawl (44) is arranged on an axially movable, non-rotatable one-way clutch pawl ring (43) which is axially prestressed toward the at least one one-way clutch tooth (46), and the at least one one-way clutch tooth (46) is arranged on the end side (45) of the first guide ring (8).

13. The disconnect clutch (1) according to claim 12, characterized in that The one-way clutch (43-46) can be closed and opened by axial movement of the one-way clutch pawl ring (43), and the axial movement can be caused by axial movement of the second guide ring (9).

14. The disconnect clutch (1) according to any one of claims 12 and 13, characterized in that The cam ring (7) and the first guide ring (8) are axially arranged between the one-way clutch pawl ring (43) and the second guide ring (9), and the second guide ring (9) or a component connected to the second guide ring (9) and unable to move axially relative to the second guide ring axially overlaps the cam ring (7) and the first guide ring (8).

15. An electric handheld power tool, in particular a screwdriver, having a shut-off clutch (1) according to one of the preceding claims.

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