Overload protection device

Abstract

Overload protection device, comprehensive: a drive (160) for generating a rotational motion, a conversion arrangement (180) for converting the rotational motion into a linear motion of an actuator (220), and a housing for storing the conversion assembly (180), wherein The conversion arrangement (180) is slidably mounted in the housing along the linear movement of the actuator (220), the overload protection device further comprising a coupling device (210, 250, 260) for disconnecting a power flow between the drive (160) and the conversion arrangement (180), the coupling device (210, 250, 260) being designed to release when a force acting on the conversion arrangement (180) is exceeded, which is oriented in the direction of the linear movement of the actuator (220), preferably the coupling device (210, 250, 260) opens in the case of both a tensile and a compressive force, characterized in that the coupling device (210, 250, 260) comprises an output gear (210), a torque transmission sleeve (250) and a torque input sleeve (260), each of which is arranged such that its Rotation axes are oriented parallel to the linear motion of the actuator (220).

Description

[0001] The present invention relates to an overload protection device for a linearly acting, mechanical actuator.

[0002] Actuators in aircraft require overload protection devices that limit the actuating force to prevent overloading of the aircraft structure. It is important that the force limiting variance is as small as possible, as the aircraft structure must be dimensioned for the maximum possible force, and low variance means low structural weight.

[0003] Linear-acting mechanical actuators typically consist of a rotary motor (e.g., electric motor) and a gearbox that converts the rotary motion into a linear motion (e.g., a threaded spindle). The gearbox is typically expanded to include speed-increasing stages in order to reduce the weight of the rotary motor. EP 1 878 658 A2 discloses the provision of clutches for overload limitation in the rotary load path in such actuators. Such overload clutches are preferably used in the high-speed range to keep the size small.

[0004] A disadvantage of such arrangements is that the force level at which the overload function becomes effective is subject to wide variation. This is due to the frictional nature of both the gearbox and the clutch.

[0005] Fig. Figure 1 describes and quantifies the relationship. It shows the behavior of the torque at the coupling with changing linear force from the actuator. Axis 10 shows the linear force in the compression direction, axis 20 in the tension direction. Axes 30 and 40 show the positive and negative torque at the coupling according to the direction of force. In the following, only the behavior in the upper right quadrant of the diagram will be considered. Analogously, the same behavior occurs in the lower left quadrant. Two operating modes are shown. Line 50 shows the torque development with increasing force for the case where the actuator drives the control surface (“drive case”), and line 60 shows the same relationship for the case where the actuator is driven by the control surface (“back drive case”). In addition, the dashed line 70 is shown, which shows the same relationship in the theoretical case where the process occurs without friction.Line 70 is valid for both the drive and reverse drive cases. Line 50 (drive case) is steeper than the dashed line 70 because more torque is required to overcome friction to generate the same force. The change in the gradient 80 shown corresponds to a gear efficiency of approximately 69%. This efficiency is realistic for a low-temperature actuator consisting of a ball screw with axial roller bearings and a spur gear with roller bearings. Line 50 rises until it meets line 90. Line 90 corresponds to the lowest torque at which the clutch releases. Similarly, line 100 shows the highest torque at which the clutch releases. This results in the friction- and manufacturing tolerance-related scatter of the clutch release torque 110.

[0006] She is in Fig. 1 is assumed to be 15%, a realistic to optimistic value for rotary overload clutches. The point of intersection of lines 50 and 90, marked 120, is now the determining factor. This defines the minimum actuating force 130 that the actuator is capable of generating. The actuator is designed such that this minimum actuating force 130 also corresponds to the actuating force that the aircraft must have available at the control surface at any moment during flight. This force is marked 100% as a reference for the force increase, which will now be discussed below.

[0007] In addition to the previously considered propulsion case, the backdraft case must also be considered. Backdraft here means that air loads act on the control surface, attempting to drive the actuator back. Backdraft must be excluded up to a load of 130, as holding loads up to this value is aerodynamically necessary. However, if in exceptional cases this load is exceeded – usually briefly – the actuator must return to the load as soon as possible to prevent damage to the aircraft structure. The magnitude of this "backdraft load" is defined in Fig. 1 can be seen when looking at line 60. Compared to line 50, the gradient of line 60 is now less than the gradient of the dashed line 70, which represents friction-free operation. This is because when the force increases due to friction, less torque reaches the clutch. The change in gradient shown by 140 corresponds to the aforementioned gearbox efficiency of approximately 69%. Line 60 rises until it meets line 100. As already described, line 100 corresponds to the highest torque at which the clutch releases. The decisive point here is the meeting point of lines 60 and 100, marked 150. This defines the maximum actuating force 160 that the actuator can counteract. With the friction conditions assumed here in the actuator, this results in a maximum load of 219%, which means that the aircraft structure must be designed to be 2.19 times stronger than aerodynamically required.It is clear that this wide dispersion of the force required to trigger the overload function represents a significant disadvantage in terms of weight and cost of the aircraft structure.

[0008] DE 10 2009 022 404 A1 discloses a spindle drive with a first load path formed by a first nut that meshes with a threaded rod, and with a second load path formed by a second nut that also meshes with the threaded rod and is arranged such that it is movable in at least one state of the spindle drive in the axial direction of the threaded rod relative to the first nut, wherein the spindle drive has a sensor unit that is designed such that it detects a relative movement between the first nut and the second nut.

[0009] It is an object of the present invention to overcome the above-mentioned disadvantages and to provide an overload protection device for linearly acting, mechanical actuators that exhibits a lower dispersion of the force required to trigger the overload function. This also leads to a reduction in the maximum load on the aircraft structure, thus enabling a weight reduction for both the actuator and the aircraft structure.

[0010] The overload protection device according to the invention comprises a drive for generating a rotational movement, a converter assembly for converting the rotational movement into a linear movement of an actuator, and a housing for supporting the converter assembly. The overload protection device is further characterized in that the converter assembly is displaceably mounted in the housing along the linear movement of the actuator.

[0011] Because the converter assembly is mounted in the housing so that it can move along the linear movement of the actuator, the converter assembly, i.e. the component group that converts a rotary movement into a linear movement, can be moved along the linear movement of the actuator in the event of an overload acting on the actuator. This occurs, for example, when an excessive tensile or compressive force acts on the actuator. The movable mounting of the converter assembly then makes it possible to disengage a coupling that transmits a power flow between the drive and the converter assembly. This is achieved simply by axially displacing the converter assembly in the direction of the linear movement of the actuator.

[0012] Since the dispersion of the release force of this overload protection device is only determined by friction in linear movements, it is independent of friction conditions in a ball screw, a gear and a rotary coupling and thus also independent of the operating modes “drive case” and “reverse drive case”, as already explained in connection with Fig. 1. The variation in the tripping force of this overload protection device is therefore significantly lower than that of a state-of-the-art overload protection device.

[0013] According to the invention, the overload protection device further comprises a coupling device for interrupting the flow of force between the drive and the converter assembly. The coupling device is designed to trigger upon exceeding a force acting on the converter assembly that is oriented in the direction of the linear movement of the actuator, thus entering a state in which the flow of force from the drive to the converter assembly is interrupted. The coupling device preferably opens in response to both a tensile and a compressive force.

[0014] For this purpose, the converter assembly is arranged in the housing of the overload protection device in such a way that it can be moved by both a tensile force from the actuator and a compressive force from the actuator. If the tensile or compressive force exceeds a predetermined level, this causes the converter assembly to move within the housing in a direction parallel to the linear movement of the actuator, thereby transferring the clutch to a decoupled state.

[0015] According to a further development of the invention, the conversion arrangement is a ball screw, preferably an inverted ball screw, which comprises a spindle nut, balls, and a spindle as an actuator. An inverted ball screw is characterized in that it has an approximately cylindrical spindle nut, on the inner surface of which a helical groove is arranged, which is suitable for receiving balls. The balls arranged therein can interact with corresponding grooves in the outer circumference of a spindle, so that when the spindle nut rotates and rotation of the spindle is prevented, a rotational movement of the spindle nut is transferred into a linear movement of the spindle.

[0016] Furthermore, according to the invention, the coupling device comprises an output gear, a torque transfer sleeve, and a torque introduction sleeve, each of which is arranged such that its rotational axes are oriented parallel to the linear movement of the actuator. Typically, the drive gear surrounds the spindle nut in a circumferential direction. The drive gear further comprises spur gear teeth extending in the direction of the linear movement of the actuator. The gear accordingly has a first toothing extending in the radial direction and a second toothing perpendicular to the radial direction, the spur gear teeth. A spur gear of a torque transfer sleeve can be engaged with this spur gear toothing. This also surrounds the spindle nut in a circumferential direction and is arranged to slide in a circumferential direction of the spindle nut. That is,The spindle nut can be rotated independently of any movement of the torque transfer sleeve. An output gear rotating around the spindle nut's rotational axis can thus transmit the rotation to the torque transfer sleeve. Furthermore, a torque introduction sleeve is provided, which is rotationally fixedly connected to the spindle nut. The torque introduction sleeve can surround the spindle nut in a circumferential direction, with the output gear also enclosing the torque introduction sleeve in a circumferential direction. Furthermore, the torque introduction sleeve also has a toothing oriented in the direction of the linear movement of the actuator in order to engage with the spur toothing of the torque transfer sleeve.

[0017] If the output gear is rotated about its axis of rotation, this only leads to a rotation of the spindle nut if the output gear and the torque introduction sleeve with their respective spur gearing are in engagement with the gearing of the torque transfer sleeve.

[0018] According to an optional modification of the invention, the output gear has outwardly directed teeth in the radial direction in order to mesh with a drive gear via an intermediate gear. In a further embodiment, not shown, the connection between the drive gear and the output gear can also be made directly via the angular gear design. The axis of the rotary motor can, for example, be perpendicular to the direction of linear movement, which can eliminate the need for an intermediate gear. Furthermore, it has spur gearing in order to be engageable with spur gearing of the torque transfer sleeve. In addition, the torque introduction sleeve can have inwardly directed teeth in the axial direction in order to engage with the converter assembly, in particular a spindle nut.The torque introduction sleeve also has a spur gear toothing in order to be able to engage with the spur gear toothing of the torque transfer sleeve.

[0019] Preferably, the drive gear is rigidly mounted on the housing with respect to the direction of the linear movement of the actuator, and the torque transfer sleeve is rigidly mounted on the converter assembly with respect to the direction of the linear movement of the actuator. When the converter assembly or a spindle nut of the converter assembly is moved in the direction of the linear movement of the spindle, the output gear is also moved accordingly towards the torque introduction sleeve. This makes it possible to release a force flow that is closed via the torque transfer sleeve. This can be done either by releasing the toothing between the torque transfer sleeve and the torque introduction sleeve or between the output gear and the torque transfer sleeve. For example, it is conceivable that the torque introduction sleeve is used to force the torque transfer sleeve out of an engaging toothing with the output gear.Alternatively, the torque introduction sleeve can also be easily pulled out of the toothing with the torque transfer sleeve due to the mobility of the converter arrangement in the direction of the linear movement of the actuator.

[0020] To ensure that the frictional connection is released only at a predetermined level, there is a fixing device that holds the converter assembly in a predetermined position with a certain force. According to a preferred embodiment of the invention, the torque introduction sleeve is mounted on the converter assembly, in particular a spindle nut of a converter assembly, so that it cannot be displaced along the direction of linear movement of the actuator.

[0021] Preferably, the torque introduction sleeve surrounds the converter assembly, in particular a spindle nut of the converter assembly, in its circumferential direction and is fixedly mounted thereon. The output gear surrounds the torque introduction sleeve in its circumferential direction, so that both the spur gearing of the output gearing and the spur gearing of the torque introduction sleeve can be simultaneously engaged with the gearing of the torque transfer sleeve.

[0022] If the spur gearing of the torque transfer sleeve meshes with both the spur gearing of the torque introduction sleeve and the spur gearing of the output gear, the frictional connection between the output gear and the torque introduction sleeve or the converter assembly is established. Rotation of the output gear about its rotational axis then leads to a rotation of the converter assembly, resulting in a linear movement.

[0023] According to a further development of the invention, the overload protection device further comprises a fixing device for elastically fixing the converter assembly to the housing with respect to a direction parallel to the linear movement of the actuator.

[0024] It can be provided that the fixing device has a spring element in which, in a state of lower tension, the tooth connection of the output gear with the torque transfer sleeve and the tooth connection of the torque transfer sleeve with the torque introduction sleeve are in engagement.

[0025] Preferably, when the converter assembly is displaced relative to the housing in the direction of the linear movement of the actuator, the coupling device changes to its open state and the compressed or reduced compressed spring element exerts a restoring force on the converter assembly in order to return the coupling device to its closed state.

[0026] Preferably, a displacement of the converter arrangement in a direction parallel to the linear movement of the actuator counteracts the state of lower tension of the spring element and leads to a disengagement of the spur gear of the output gear or the torque introduction sleeve with the torque transfer sleeve.

[0027] Furthermore, it can be provided that the spring element is designed to exert a force on the converter arrangement in order to displace it in such a way that the coupling device returns to its non-positive state.

[0028] According to an optional modification of the invention, the spring element is arranged between the torque transfer sleeve and a disc surrounding a spindle nut of the converter arrangement, which disc is displaceable in the longitudinal direction of the spindle nut.

[0029] Preferably, the torque introduction sleeve is designed in one piece with the conversion arrangement, in particular a spindle nut of a conversion arrangement.

[0030] The invention further relates to an actuator comprising an overload protection device according to one of the variants listed above.

[0031] Also encompassed by the invention is an aircraft having an actuator as defined above.

[0032] Further features, details, and advantages are evident from the following description of the figures. They show: Fig. 1: a diagram explaining the disadvantages of state-of-the-art overload protection, Fig. 2: a schematic cross-sectional view of the overload protection device according to the invention, Fig. 3: a perspective sectional view of the coupling device, Fig. 4: a perspective sectional view of the coupling device in which the torque transfer sleeve is spaced apart, Fig. 5: a schematic cross-sectional view of the overload protection device when a pressure force is applied to the actuator, which leads to the opening of the coupling device, Fig. 6: a schematic cross-sectional view of the overload protection device with a force flow indicated when a compressive force acts on the actuator, Fig. 7: a perspective view of the coupling device in a state of the coupling device decoupled due to pressure force, Fig. 8: a schematic cross-sectional view of the overload protection device when a tensile force acts on the actuator, which leads to the opening of the coupling device, Fig. 9: a schematic cross-sectional view of the overload protection device with a force flow indicated when a tensile force acts on the actuator, Fig. 10: the coupling device in a perspective partial sectional view in a state decoupled due to tensile force, Fig. 11: a schematic cross-sectional view of the overload protection device when the actuator hits an end stop, which leads to the opening of the coupling device, and Fig. 12: a schematic cross-sectional view of the overload protection device in the event of a stop at another end stop, which leads to the opening of the coupling device.

[0033] The basic idea of ​​the invention is to position the overload protection device as close as possible to the actuator output in order to minimize the influence of friction and thus the dispersion of the trigger force. To this end, the overload protection device is placed in the linearly acting area of ​​the actuator. Fig. 2 to Fig. Figure 7 shows an exemplary embodiment of the invention. The exemplary actuator consists of an electric motor 160, which drives an inverted ball screw 180 via a spur gear 170. The gear consists of a drive gear 190, an intermediate gear 200, and an output gear 210.

[0034] The intermediate gear 200 is required to create an axial offset from the ball screw 180 that is sufficiently large to accommodate the space requirements of the electric motor. The inverse ball screw 180 consists of a spindle 220, a spindle nut 230, and balls 240. The functional interaction of spindle 220, spindle nut 230, and balls 240 is identical to the known ball screw drive. The spindle 220 is prevented from rotating by an arrangement not shown. The spindle nut 230 is prevented from axial movement during rated operation by the arrangement described below. In this context, rated operation refers to any operation outside the period when the overload protection is activated. Due to this restriction of the degrees of freedom, the spindle 220 experiences the desired linear movement as a result of rotation of the spindle nut 230.

[0035] According to the invention, overload protection is achieved by opening the torque-transmitting connection between spindle nut 230 and output gear 210 when a limit value of the axial force on spindle 220 is exceeded. This allows spindle nut 230 to rotate independently of the electric motor, and spindle 220 can retract under the external force. The detachable torque-transmitting connection consists of the components output gear 210, torque transfer sleeve 250, and torque introduction sleeve 260. The three components have spur gears as shown in Fig. 4 shown.

[0036] Fig. 3 is a spatial, sectional view of the three components in the state as in Fig. 2 shown.

[0037] Fig. 4 is the same arrangement as in Fig. 3, but axially separated so that the spur gears are more visible. The torque flow from the electric motor goes to the gearbox 170, from there to the output gear 210, via the spur gear of the output gear 210 to the torque transfer sleeve 250, from there to the torque introduction sleeve 260, which then introduces it via radial claws 270 into the spindle nut 230. To ensure torque transmission during nominal operation, the gears must mesh. The meshing of the spur gear between the torque transfer sleeve 250 and the torque introduction sleeve 260 is ensured by the disc spring assembly 280, which is preloaded with the trigger force of the overload protection device. The force flow of this preload force is as follows: From the right end of the disc spring assembly 280, the preload force enters the torque transfer sleeve 250, which is axially supported on the torque introduction sleeve 260.From there, the preload force is transmitted to the inner ring of the radial bearing 290 and from there via the support ring 300, the spindle nut 230, the axial bearing 310 and the disc 320 back to the disc spring assembly 280. The meshing of the spur gearing between the output gear 210 and the torque transfer sleeve 250 is ensured by the arrangement being located with only minimal axial play between the stationary axial bearings 320 and 330, which prevents the spur gearing from opening.

[0038] Fig. Figure 5 now shows the condition when the compressive force 340 on the actuator exceeds the trigger force of the overload device. The compressive force 340 exceeds the preload force of the disc spring assembly 280, causing the spur gears of the output gear 210 and the torque transfer sleeve 250 to separate.

[0039] Fig. Figure 6 shows the force flow through the actuator. The spindle nut no longer has a torque-transmitting connection to the electric motor 160, begins to rotate under the pressure load 340, and the spindle 220 retreats. The position of the spur gears relative to each other in this state is also shown in Fig. 7. An arrangement 350 fixes the output gear 210 axially and prevents the output gear 210 from moving axially to the left as a result of the axial movement for compressing the disc spring assembly 280, thus preventing the spur gears of the output gear 210 and the torque transfer sleeve 250 from separating from one another.

[0040] Fig. Figure 8 shows the condition when the tensile force 360 ​​on the actuator exceeds the trigger force of the overload device. The tensile force 360 ​​exceeds the preload force of the disc spring assembly 280, causing the spur gears of the torque transfer sleeve 250 and the torque introduction sleeve 260 to separate.

[0041] Fig. Figure 9 shows the force flow through the actuator. The spindle nut no longer has a torque-transmitting connection to the electric motor 160, begins to rotate 360° under the tensile load, and the spindle 220 moves in the direction of the tensile force. The position of the spur gears relative to each other in this state is also shown in Fig. 10. An arrangement 370 fixes the torque introduction sleeve 260 axially to the spindle nut 230 and prevents the torque introduction sleeve 260 from moving axially as a result of the axial movement for compressing the disc spring assembly 280 and thus prevents the spur gear teeth of the torque transfer sleeve 250 and the torque introduction sleeve 260 from separating from one another.

[0042] The dispersion of the release force of this overload protection device is determined only by friction in linear movements and is therefore independent of friction conditions in the ball screw, gear and rotary coupling and thus also independent of the operating modes “drive case” and “reverse drive case”, as in Fig. 1. The variation in the release force of this overload protection device is therefore significantly lower than that of state-of-the-art overload protection devices. The disc spring assembly contributes the largest proportion of friction in the linear movement. However, since it is compressed under both a compressive load of 340 and a tensile load of 360, thus always experiencing the same direction of movement, this friction component always acts in the same direction and can be compensated for by adjusting the preload force of the disc spring assembly 280. Therefore, the variation in the release force of this overload protection device does not include the entire friction hysteresis of the disc spring assembly 280, but only the variation of the ascending branch of the friction hysteresis.

[0043] It is another standard requirement for such actuators that travel at full speed against the device's internal travel limits must not result in damage to the actuator. Such travel to the end stop does not occur during nominal operation, as such actuators operate in travel-limiting control circuits. However, this cannot be ruled out during installation or inspection work. Any resulting damage could go undetected and impair safe flight operations. Fig. 11 and Fig. 12 it is clear that this requirement can also be covered by the invention.

[0044] Fig. 11 shows the triggering of the overload function when traveling to the end stop in the extension direction, Fig. 12 the same in the retraction direction. At the moment when the spindle 220 reaches the internal end stop 380 (in Fig. 11) or 390 (in Fig. 12), a torque builds up at the spindle nut 230, since, on the one hand, the drive torque is still applied to the electric motor 160 and, on the other hand, the sudden change in speed due to the blockage causes a moment of inertia, which is added to the drive torque. This torque sum is converted by the ball screw 180 into a linear force, which, analogous to the process described above, leads to the separation of the affected spur gear (in Fig. 11 Separation of output gear 210 and torque transfer sleeve 250, and in Fig. 12 Separation of torque transfer sleeve 250 and torque introduction sleeve 260). After separation, the electric motor 160 can continue to rotate until a typically present, higher-level system monitoring system detects the faulty motor rotation and disconnects the electric motor 160 from the power supply. The actuator comes to rest without experiencing a damaging load peak.

Claims

[1] Overload protection device, comprising: a drive (160) for generating a rotational movement, a conversion arrangement (180) for converting the rotational movement into a linear movement of an actuator (220), and a housing for supporting the converting arrangement (180), wherein the converter assembly (180) is mounted displaceably in the housing along the linear movement of the actuator (220), wherein the overload protection device further comprises a coupling device (210, 250, 260) for separating a force flow between the drive (160) and the converter assembly (180), wherein the coupling device (210, 250, 260) is designed to trigger when a force acting on the converter assembly (180) that is oriented in the direction of the linear movement of the actuator (220) is exceeded, preferably the coupling device (210, 250, 260) opens both under a tensile and a compressive force, characterized bythat the coupling device (210, 250, 260) comprises an output gear (210), a torque transfer sleeve (250) and a torque introduction sleeve (260), each of which is arranged such that its axes of rotation are oriented parallel to the linear movement of the actuator (220). [2] Overload protection device according to claim 1, wherein the conversion arrangement (180) is a ball screw, preferably an inverse ball screw, which comprises a spindle nut (230), balls (240), and a spindle as an actuator (220). [3] Overload protection device according to one of the preceding claims, wherein the output gear (210) has an outwardly directed toothing in the radial direction in order to mesh with a drive gear via an intermediate gear, or has the toothing of an angular gear, and has a spur toothing in order to be engageable with a spur toothing of the torque transfer sleeve (250), and the torque introduction sleeve (260) has an inwardly directed toothing in the radial direction in order to engage with the conversion arrangement (180), in particular a spindle nut (230), and has a spur toothing in order to be engageable with the spur toothing of the torque transfer sleeve (250). [4] Overload protection device according to one of the preceding claims, wherein the output gear (210) is arranged rigidly on the housing with respect to the direction of linear movement of the actuator (220) and the torque transfer sleeve (250) is arranged rigidly on the converter assembly (180) with respect to the direction of linear movement of the actuator (220). [5] Overload protection device according to one of the preceding claims, wherein the torque introduction sleeve (260) is mounted on the converter arrangement (180), in particular a spindle nut (230), in a non-displaceable manner along the direction of a linear movement of the actuator (220). [6] Overload protection device according to one of the preceding claims, wherein the torque introduction sleeve (260) surrounds the converter assembly (180), in particular a spindle nut (230) of the converter assembly (180), in its circumferential direction and is fixedly arranged thereon, and the output gear (210) receives the torque introduction sleeve (260) in its circumferential direction, so that simultaneously both the spur toothing of the output gear (210) and the spur toothing of the torque introduction sleeve (260) can be brought into engagement with the toothing of the torque transfer sleeve (250). [7] Overload protection device according to one of the preceding claims, further comprising a fixing device for elastically fixing the converter assembly (180) to the housing with respect to a direction parallel to the linear movement of the actuator (220). [8] Overload protection device according to claim 7, wherein the fixing device comprises a spring element (280) in which, in a state of reduced tension, the tooth connection of the output gear (210) is in engagement with the torque transfer sleeve (250) and the tooth connection of the torque transfer sleeve (250) is in engagement with the torque introduction sleeve (260). [9] Overload protection device according to claim 8, wherein upon displacement of the converter assembly (180) relative to the housing in the direction of the linear movement of the actuator (220), the coupling device (210, 250, 260) changes into its open state and the compressed or reduced compressed spring element (280) exerts a restoring force on the converter assembly (180) in order to return the coupling device (210, 250, 260) to its closed state. [10] Overload protection device according to one of claims 8 to 9, wherein a displacement of the converter arrangement (180) in a direction parallel to the linear movement of the actuator (220) counteracts the state of reduced tension of the spring element (280) and leads to a disengagement of the spur gearing of the output gear (210) or the torque introduction sleeve (260) with the torque transfer sleeve (250). [11] Overload protection device according to one of claims 8 to 10, wherein the spring element (280) is designed to exert a force on the converter assembly (180) in order to displace it such that the coupling device (210, 250, 260) returns to its force-locking state. [12] Overload protection device according to one of claims 8 to 11, wherein the spring element (280) is arranged between the torque transfer sleeve (250) and a disc surrounding a spindle nut (230) of the converter assembly (180) which is displaceable in the longitudinal direction of the spindle nut (230). [13] Overload protection device according to one of the preceding claims, wherein the torque introduction sleeve (260) is designed in one piece with the converter assembly (180), in particular a spindle nut (230) of a converter assembly (180).

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