Method for for the safe operation of an actuator

Abstract

The invention relates to a method for the safe operation of an actuator (1). The actuator is designed to provide torque and comprises a linear drive (2) and a gearing (3) for converting a linear movement into a rotational movement of a shaft (5), wherein: the gearing (3) comprises a lever (4) which rotationally drives the shaft (5) to which the torque is to be applied; the gearing (3) also has a coupling element (6); the coupling element (6) is connected to the linear drive (2) via a first connection point (7), and to the lever (4) via a second connection point (8) so that energy is transferred between the linear drive (2) and the lever (4) exclusively via the coupling element (6); and the coupling element (6) is rotatably connected in both connection points (7, 8). According to the invention, the maximum force provided by the linear drive (2) is limited according to a current value of a gear ratio of the gearing (3).

Description

[0001] Procedure for the safe operation of an actuator

[0002] The present invention relates to a method for the safe operation of an actuator having the features according to the preamble of claim 1.

[0003] Such actuators are already known from DE 10 2016 207 827 A1, which provide a nonlinear actuation force for an actuation unit for an automatic transmission (preferably a PRND automatic transmission system) of a motor vehicle. A corresponding guide track is provided to generate the nonlinearity.

[0004] In general, such an actuator is already known from DE 10 2018 116 133 A1.

[0005] The applicant's as yet unpublished German patent application with the file number 10 2023 115 292.0 also discloses an actuator with a nonlinear characteristic curve. Due to the toggle lever kinematics used in this actuator concept, with a constant drive torque of the electric motor in an end position (Fig. 1, Fig. 8) of the toggle lever mechanism, an actuating force (torque) on the output shaft (5) essentially tends toward infinity, which can lead to damage to the load to be actuated or to parts of the actuator itself.

[0006] The present invention aims to operate such an actuator safely in a simple manner.

[0007] This object of the invention is achieved by a method having the features of claim 1.

[0008] A method is therefore provided for the safe operation of an actuator, wherein the actuator is provided for providing a torque, with a linear drive and a gear for converting a linear movement into a rotary movement of a shaft, wherein the gear comprises a lever which rotary drives the shaft to be subjected to the torque, wherein the gear further comprises a coupling element and wherein the coupling element is connected to the linear drive via a first connection point and to the lever via a second connection point, so that energy is transferred between the linear drive and the lever exclusively via the coupling element, and wherein the coupling element is rotatably connected at both connection points. It is provided that the maximum force provided by the linear drive is limited as a function of a current value of a gear ratio of the transmission.

[0009] The current value of the gear ratio of the gearbox depends on the travel position along the linear drive's motion axis, for example, a spindle of a spindle drive, and is either learned at end-of-line or redetermined in a referencing or update process. The current gear ratio is therefore the value for the gear ratio at the current travel position.

[0010] In a preferred embodiment of the invention, it is provided that the lever is connected at a second lever end via a third connection point in a rotationally fixed manner to the shaft and at a first lever end in a rotationally fixed manner to the coupling element via the second connection point, and the coupling element is connected rotatably to the linear drive via the first connection point, and the lever establishes a rigid connection between the two connection points.

[0011] In a further preferred embodiment of the invention, it is provided that in an initial position of the transmission, a first stop, preferably fixed to the housing, is provided for fixing the initial position and / or in an end position of the transmission, a second stop, preferably fixed to the housing, is provided for fixing the end position, and wherein the first lever end is designed for abutting the lever against the first and / or second stop.

[0012] In an alternative preferred embodiment of the invention, it is provided that in an end position of the gear, a second stop, preferably fixed to the housing, is provided for determining the end position, and wherein a spindle end or an end cap of a spindle of the linear drive is designed to stop the spindle against the second stop. In a further preferred embodiment of the invention, it is provided that the value of the gear ratio at the travel position along the movement axis of the linear drive is calculated from the ratio of a rotation angle Acp to be determined, which results from the rotational movement of the shaft resulting from the movement of the linear drive, and a predefined distance Ax that the linear drive moves along the movement axis of the linear drive, starting from the travel position.

[0013] The current travel position is the position between the start position and the end position at which a given point on the spindle, for example the spindle center, the spindle end or the end cap of the spindle of the linear drive, is currently located during the movement of the spindle.

[0014] A specified spindle advance, for example, designated as Ax, results in a determined shaft rotation, designated as Acp. The transmission ratio is determined as the quotient of both values, Acp / Ax.

[0015] Due to the non-linearity of the toggle lever kinematics, the gear ratio is not constant throughout the entire travel between the initial and final positions, but rather assumes different values ​​at each position between the initial and final positions. For each travel position between the initial and final positions, the gear ratio value at that travel position is determined as the quotient Acp / Ax. This is primarily done end-of-line, but can also be requested on demand or regularly by a higher-level control process.

[0016] In a further preferred embodiment of the invention, it is provided that the course of the values ​​of the gear ratio is stored as a function of the travel position of the linear drive.

[0017] In a further preferred embodiment of the invention, the dependence of the gear ratio values ​​on the travel position of the linear drive is non-linear. In a further preferred embodiment of the invention, the end position has a predetermined end position threshold value for the gear ratio.

[0018] In a particularly preferred embodiment of the invention, it is provided that the force of the linear drive is limited along the movement axis of the linear drive when the movement direction of the linear drive is towards the end position and the gear ratio at the current position exceeds the end position threshold value.

[0019] In a preferred embodiment of the invention, this limitation stops the linear drive.

[0020] In this way, the linear drive, for example the spindle, can advantageously be brought to a stop shortly before reaching the stop, so that the actuator comes to a stop position shortly before actually reaching the end position. The actual end position can therefore be selected such that the stop position, i.e. the position of the actual stop, is also the actually desired stop position, for example, shortly before reaching the end position or stop. In this way, not only can the actually desired stop position be reached, but also - as desired - not overrun, thus advantageously preventing the stop from being reached or overloading the actuator or the load to be moved.

[0021] According to the invention, the drive torque of an energy converter, for example an electric motor for driving a spindle nut of the linear drive, is varied depending on the gear ratio of the toggle lever mechanism predetermined by the kinematics, wherein in particular a reduction is provided towards the end position (Fig. 1, Fig. 6, Fig. 8) so that no overload occurs. This can be done directly as a function of the gear ratio of the toggle lever, which requires active braking when moving towards the end position shortly before reaching the end position (Fig. 1, Fig. 6, Fig. 8) in order to compensate for actuator inertia. During active braking, the drive of the linear drive generates a braking torque, if necessary by reversing the current supply. Active braking can also be provided when moving towards the start position shortly before reaching the start position.In this way, depending on the intended use, maximum dynamics of the system could be achieved if required.

[0022] If maximum safety is required, the event of a power failure at the actuator can also be considered. For example, in a scenario where the power failure occurs just as the braking torque is being requested. Taking into account the known inertias, only the braking torque without any current supply is considered, and the drive is switched off earlier in the direction of the end position, before reaching the end position, than in the case where an increased braking torque could be provided by reversing the current supply. In this way, overloading caused by the toggle lever kinematics of the load to be actuated or the actuator itself can be prevented in any state of the actuator.

[0023] Depending on the downstream load to be actuated, the torque reduction according to the invention can also be provided in only one direction of movement. This is the case, for example, when actuation is carried out against an elastic element, such as a spring, in one direction of actuation, so that avoidable potential damage can be largely eliminated.

[0024] It can be provided that, in addition to the lever and the linear drive, a third component is provided with the coupling element, which connects them, which can be assembled in a particularly simple manner and enables a non-linear characteristic curve of the actuator through a corresponding transfer of energy from the linear drive to the lever and thus to the shaft. Furthermore, it can be provided that the lever is connected in a rotational manner to the shaft at a first lever end via a third connection point and is connected in a rotational manner to the coupling element at a second lever end via the second connection point, and the lever creates a rigid connection between the two connection points. By adjusting the positions of the connection points and the length of the coupling element, the non-linearity of the actuator can be adjusted in a simple manner, since it is not the distance between the second lever end and the shaft that can be varied, but only the transmitted torque orthe corresponding rotational speed. In other words, the position of the third connection point fixed to the housing defines the movement of the lever in space as a constraint, and the rotational speed and torque of the shaft are determined by the length of the coupling element in conjunction with its position on the linear drive.

[0025] It can be provided that the coupling element creates a rigid connection between the first and second connection points, so that a linear movement of the first connection point by the linear drive results in a first pivoting movement of the second connection point about the first connection point, as well as in a second pivoting movement of the second connection point about the third connection point, so that due to the rotationally fixed connection of the lever to the shaft, a rotation of the shaft is caused by the second pivoting movement.

[0026] The path traveled by the second connection point is determined by the constraint of the rigid lever. The corresponding superposition of the two pivots to form a fixed curve determines the nonlinearity of the rotational speed or the transmitted torque.

[0027] It can be provided that the coupling element connects the lever and the linear drive to one another in such a way that the second connection point is moved along a trajectory curve, so that in a first operating range around a first end point of the trajectory curve, a movement of the first connection point is translated by the linear drive into a first rotational movement of the shaft, and in a second operating range around a second end point, a movement of the first connection point is translated by the linear drive into a second rotational movement of the shaft, wherein the first rotational movement covers a larger angular range with a smaller force transmission than the second rotational movement in a time interval. In this way, specific operating points and a transition range lying between them for the actuating force of the shaft can be defined, which correspond to a desired non-linearity of the actuation and merge into one another.

[0028] Furthermore, it can be provided that at the second end point, the coupling element is aligned perpendicular to the lever and the movement axis of the linear drive, and the lever is aligned parallel to the movement axis. Force transmission is difficult in such an arrangement. The force acting from the linear drive on the coupling element acts perpendicular to the tangent of the circular arc described by the second lever end. The transmitted torque is very small, and accordingly, a high rotational speed can be achieved. This arrangement also provides self-locking of the actuator. This is even more true when friction points on the actuator are taken into account.

[0029] In a second possible arrangement, the coupling element can be aligned parallel to the linear drive's axis of motion and perpendicular to the lever at the first end point. This results in maximum torque and minimum rotational speed. Accordingly, a stable actuator position is also achieved here.

[0030] It can be provided that a first, preferably housing-fixed, stop is provided in the first end point for fixing the first end point and / or a second, preferably housing-fixed, stop is provided in the second end point for fixing the second end point, and wherein the second lever end is designed to stop the lever against the first and / or second stop. In this way, the two stable end points of the actuator can be approached reliably and also held against vibrations. The stops can, for example, be provided as an extension of a spindle of the linear drive on an actuator housing and in the opposite end position as a stop for the lever.

[0031] It can be provided that the first and / or second stop is formed integrally from an actuator housing.

[0032] The advantage of positioning the stops on the housing instead of limiting the linear adjustment range of the linear drive within the linear drive is that a rotor bearing of the linear drive is positioned between the linear drive and the lever, resulting in a further development. Thus, the total friction coefficient, which is primarily determined by the sliding friction values ​​within the linear drive and the stops, and only negligibly influenced by the rolling friction value of the rotor bearing, does not fluctuate as much as a combination of only sliding friction points. This allows the required drive torque of the linear drive, which is necessary to ensure secure clamping in the stops, to be more precisely defined.

[0033] The process for safely clamping the actuator at its end points involves slowing down / moving the linear drive to a particular stop range. This means, for example, that a spindle enclosed by the linear drive is moved to one of the stops and / or the lever is moved to the other stop. As the process continues, the linear drive continues to move in the same direction, or a corresponding spindle continues to rotate even after the respective stop has been reached, and the linear drive, spindle, or lever are moved with a defined torque that is well below the maximum possible torque of a motor or electric motor driving the linear drive or spindle. This ensures that the clamping can be safely released even under changed boundary conditions (fluctuations in lubrication, temperature, power supply, etc.), allowing transition to normal operating conditions.In order to enable the stops to be approached in a particularly controlled manner for adjusting or calibrating the actuator, it can be provided that the first and / or second stop have a specific softness so that a predetermined linear movement of the linear drive is possible.

[0034] The required locking torque can also be predetermined to a reasonable value via the effective radius of the stops for the spindle or the lever or their variation during design.

[0035] Since no additional components are required for the stops, but only an adapted geometry of the actuator housing, the securing of the end stops can be implemented almost cost-neutrally.

[0036] An actuator comprising a linear drive and gearing for converting a linear movement into a rotary movement can be provided. In principle, various types of linear drives based on different principles are well known to those skilled in the art, be they mechanical or hydraulic linear drives. The linear drive can be formed, for example, by a ball screw drive or a planetary roller screw drive. The linear movement can accordingly be provided by a nut on a spindle or by a spindle itself. The rotary movement of a shaft is generated by a lever that is connected to the shaft in a rotationally fixed manner. A rigid connection is established between the lever and the linear movement element (nut or spindle, or similar) of the linear drive by a coupling element. This meansThe connection point of the coupling element on the linear drive is moved exclusively along a straight line, the connection point of the coupling element on the lever is pivoted exclusively along a circular path with a predetermined radius r around the axis of the shaft, while the distance between the two connection points on the lever and the linear drive always remains the same. In this way, a trajectory curve of the second connection point on the lever is realized, which provides a faster angular velocity at a lower torque in a first working range and a lower angular velocity at a higher torque in a second working range to drive the shaft. There is a corresponding transition area between the two working ranges. In this way, a rotational movement with a variable characteristic curve can be provided by the shaft, i.e.in a first angular range with a higher angular velocity than in a second angular range and a correspondingly lower torque in the first angular range than in the second angular range. This rotational movement can be used to actuate disconnect units, clutches, brakes, or parking locks within the drivetrain of a motor vehicle or commercial vehicle.

[0037] The toggle lever mechanism described here creates a nonlinear characteristic curve between the linear advance of the linear actuator, e.g., a spindle travel and the rotation of the lever, or the drive force of the linear actuator, or the spindle force and the torque of the lever. This makes such an actuator particularly suitable for actuating loads that also have a nonlinear actuation force characteristic curve.

[0038] An example of this would be the activation of a parking lock.

[0039] This arrangement allows the shaft for actuating the laser to be positioned very close to the linear drive - significantly closer than if a comparably large actuating torque were generated by an actuating lever alone.

[0040] An embodiment of the method according to the invention, to which it is not limited, and from which further features according to the invention can result, is shown in Figures 8, 9 and 10. They show:

[0041] Fig. 1 an actuator in a partial sectional view

[0042] Fig. 2: symbolic representation of a trajectory curve of the second connection point 8 of the lever 4 for actuating the shaft 5 of the actuator according to Fig. 1

[0043] Fig. 3 alternative design of the actuator

[0044] Fig.4 symbolic representation of an alternative trajectory of the second connection point 8 of the lever 4 for actuating the shaft 5 when actuating the actuator according to Fig. 3 Fig.5 Actuator according to Fig. 1 , additional stops on the actuator housing (second connection point 8 in the first end point 21 )

[0045] Fig. 6 Actuator according to Fig. 1 , additional stops on the actuator housing (second connection point 8 in the second end point 22) (near the end point 22: maximum torque on the shaft 5 when the spindle 50 moves towards or away from the end point 22)

[0046] Fig. 7 one half of an actuator housing

[0047] Fig. 8 Explanation of the method according to the invention: Actuator in the end position of the toggle lever (Fig. 8 identical to Fig. 1 but without reference numerals)

[0048] Fig. 9 Explanation of the method according to the invention: Actuator according to Fig. 8 in a middle position of the toggle lever

[0049] Fig. 10 Explanation of the method according to the invention: Actuator according to Fig. 8 in initial position of the toggle lever

[0050] Fig. 1 shows an actuator 1 for converting a linear movement of a linear drive 2 into a rotational movement 23,24 of a shaft 5.

[0051] For this purpose, the linear drive 2 comprises a spindle 50. The spindle 50 has an end cap 51, which is connected here on one side to a coupling element 6 via a support roller 52. Instead of only one support roller 52 on one side as shown here, support rollers can also be connected on both sides, each with its own coupling element.

[0052] The support roller 52 represents a first connection point 7 for the rotatable mounting of the coupling element 6.

[0053] The coupling element 6 is designed as a linearly extending, rigid sheet metal part, which is connected at one end to the spindle 50 via the first connection point 7 and to a lever 4 via a second connection point 8 at the second end. The coupling element 6 is also rotatably mounted on the lever 4 via the second connection point 8.

[0054] The lever 4 extends from its first lever end 9 with the second connection point 8 to a third connection point 10 at the second lever end 11. The lever 4 is rotationally connected to a shaft 5 at the third connection point 10. For this purpose, the lever 4 has a hole 53 with an internal toothing 54. The shaft 5 has a corresponding external toothing 55, which engages with the internal toothing 54. The shaft 5 is rotatably mounted in an actuator housing 40 and extends through the actuator housing 40 in the direction of a shaft axis 56. The shaft axis 56 runs perpendicular both to the movement axis 41 of the spindle 50 and to the extension direction 57 of the coupling element 6.

[0055] Outside the actuator housing 40, the shaft 5 is connected to an actuating element 60. This can be an eccentric disc, a contoured disc, or the like, which is set in rotation by the shaft 5. A parking lock, a brake, a clutch, or the like can be actuated via this actuating element 60.

[0056] Spindle 50, end cap 51, coupling element 6 and lever 4 are components of a gear 3, which converts a linear movement of the spindle 50 of the linear drive 2 into a rotational movement 23,24 of the shaft 5 to drive the actuating element 60.

[0057] In Fig. 1, the spindle 50 is in a position P1, whereby the direction of extension 57 of the coupling element 6 is practically perpendicular to the movement axis 41 of the spindle 50 and to the lever 4. In position P1, the spindle 50 is practically fully extended and the second connection point 8 is located at a second end point 22. If the spindle 50 is retracted, the corresponding travel path of the spindle 50 is coupled to a smaller travel path of the second connection point 8 perpendicular thereto via the coupling element 6. This means that in this case the linear movement of the linear drive 2 is converted into a second rotational movement 24. In this case, a maximum torque is transmitted to the shaft 5 at a minimum rotational speed.

[0058] An illustration of the transmitted torque and the associated rotational speed is shown in Fig. 2. In the left-hand part of Fig. 2, the second connection point 8 is located at the second end point 22, as also shown in Fig. 1, and in the right-hand part it is located at a first end point 21. At the second end point 22 of the second connection point 8, the first connection point 7 of the coupling element 6 is located on the movement axis 41 of the spindle 50. A linear movement for retracting the spindle 50 in the direction 61 pulls the lever 4 via the second connection point 8 into a second rotational movement 24 around the third connection point 10. The second connection point 8 follows a trajectory curve 20 with the distance r between the second connection point 8 and the third connection point 10. This movement of the lever 4 is characterized by a minimum rotational speed and a maximum torque at the second end point 22.

[0059] In the right part of Fig. 2, the second connection point 8 is located at a first end point 21. Here, the spindle 50 is retracted so far that the lever element 4 lies practically completely parallel to the spindle 50 on the movement axis 41. Extending the spindle 50 then leads to a maximum rotational speed and minimum torque of the lever 4.

[0060] In the area between the two end points 21, 22, the lever 4 is thus driven with a nonlinear torque characteristic. Shaft 5 is driven accordingly, and the nonlinear characteristic of shaft 5 can be used to actuate a nonlinear load, such as a parking lock.

[0061] Fig. 3 shows an alternative arrangement of the coupling element 6 between the lever 4 and the spindle 50. The spindle 50 is here in the retracted position P2, with the second connection point 8 then being located at the second end point 22. In the parallel position of the coupling element 6, it is positioned such that it covers the spindle 50 in the direction of the movement axis 41. In contrast to the embodiment according to Figures 1 and 2, the coupling element 6 is tilted by 90°. An illustration of the torques generated by this actuator can be found in Fig. 4. Here, a first end point 21 of the second connection point 8 is shown on the left side, while a second end point 22 is shown on the right side. In between, the second connection point 8 is moved along the trajectory curve 20'. Here too, a maximum torque is transmitted to the shaft 50 at the second end point 22 (right) and a minimum torque at the first end point 21.Accordingly, the shaft 50 is subjected to a first rotational movement 23 at the first end point 21 and a second rotational movement 24 at the second end point 22. The length of the arrows of the rotational movements 23, 24 symbolize the transmitted torque.

[0062] The trajectories 20 and 20' of the two alternatives in Figs. 2 and 4 are practically mirrored and otherwise identical. However, the rotational directions at minimum and maximum torque of shaft 5 are reversed, i.e., the rotational movements 23 and 24' are reversed and equal in magnitude. In the first example in Fig. 2, the maximum torque is transmitted when the spindle 50 is retracted; in the second alternative according to Fig. 4, however, it is transmitted when the spindle 50 is extended.

[0063] The alternative embodiment of an actuator 1 according to Fig. 1 shown in Fig. 3 also has a coupling element 6' with two parallel partial coupling elements 6a on both sides of the spindle 50. Such a coupling element 6' also enables actuation according to the alternative in Fig. 4.

[0064] However, the same applies to the generation of the non-linear characteristic curve of shaft 5 as already described in Fig. 1.

[0065] In Figs. 5 and 6, an actuator according to Fig. 1 is shown, in which the drive by a spindle drive is shown in a sectional view and further stops 30, 31 for the lever 4 and the spindle 50 are provided on the actuator housing 40.

[0066] In Fig. 5, the lever 4, or the second connection point 8, is located at a first end point 21; in Fig. 6, the second connection point 8 is shown at the second end point 22. Starting from an actuator position according to Fig. 6, a maximum torque is generated on the shaft 5 when the spindle 50 is retracted in the direction of the linear drive 2.

[0067] In Fig. 5, the lever 4 is positioned at the first end point 21 against the first stop 30. The first stop 30 is formed as an integrated component of the actuator housing 40. If a predetermined torque is now applied by the spindle 50 or by the spindle drive 70, which torque presses the lever 4 or the first lever end 9 against the first stop 30 with a predetermined stop force, then the position of the lever 4 and thus the angular position of the shaft 5 can be clearly defined and the actuator 1 can generally be secured against displacement, for example due to vibrations.

[0068] In Fig. 6, the lever 4, or rather the second connection point 8, is located at the second end point 22. The second stop 31 is now provided for the spindle 50, or rather the end cap 51 of the spindle 50. Similarly, the spindle 50 can now be pressed against the second stop 31 with a predetermined torque. Here, too, the position of the lever 4 and thus the angular position of the shaft 5 can be clearly defined, and the actuator 1 can generally be secured against adjustments, for example, due to vibrations.

[0069] Figs. 5 and 6 further show that the spindle 50 is driven by a nut 71. This nut is connected to the spindle via a toothed point 72. Since the spindle 50 is non-rotatably mounted in the actuator housing 40, the rotational movement of the nut 71 is correspondingly converted into the linear movement of the spindle 50. The spindle 50 is supported on the actuator housing 40 via the nut 71 and a rotor bearing 73. The drive of the nut 71 is realized via a rotor 74 of an electric motor 75.

[0070] Since, as shown here, the rotor bearing 73 is arranged axially between the stops 30, 31 and the rotor 74, the torque which is necessary for a secure clamping of the lever 4 or the spindle 50 at the first or second stop 30, 31 can be determined more precisely, since the accumulated friction coefficient, which is mainly determined by the sliding friction coefficients (spindle / nut, stop surfaces) and only negligibly by the rolling friction coefficient of the rotor bearing, does not fluctuate as much as a combination of only sliding friction points.

[0071] In Fig. 7, one half of an actuator housing 40 is shown.

[0072] The actuator housing 40 has an internal contour 42. This contour 42 is embossed into the actuator housing 40 parallel to the spindle 50 and serves to accommodate a bearing element 43. The bearing element 43, as shown in Fig. 1, is arranged at one end of the spindle 50 and supports the spindle 50 on the actuator housing 40. As shown in Fig. 1, it is preferably designed as a support roller 52. The bearing element 43 coincides with the first connection point 7. This bearing element 43 preferably consists of two support rollers 52, which are arranged around the articulated first connection point 7 between the spindle 50 and the coupling element 6, preferably on both sides at the end of the spindle 50, and which are supported on correspondingly positioned support surfaces 44 of the contour 42 in the actuator housing 40 and can roll there. In this way, the efficiency of the actuator 1 can be improved (in principle, plain bearings on one or both sides are also conceivable).The support surfaces 44 preferably run parallel to the movement axis 41 of the spindle 50 or the linearly displaceable element of the linear drive 2.

[0073] By means of the actuator 1 shown here, which operates according to the toggle lever principle, a non-linear actuation characteristic can be easily implemented on an actuating element 60 via a linear drive 2. The stops 30, 31 provided can prevent accidental adjustment due to vibrations or the like, and can also ensure a defined position of the actuator 1, e.g., in the event of a power failure.

[0074] Safe actuation with good efficiency can be achieved via the support surfaces 44 in conjunction with the support rollers 52.

[0075] The toggle lever mechanism thus results from spindle 50, coupling element 6, lever 4 and shaft 5, wherein the end of the spindle 50 is rotatably connected to one end of the coupling element 6 at the first connection point 7 and the other end of the coupling element 6 is rotatably connected to one end 9 of the lever 4 at the second connection point 8 and the other end 11 of the lever 4 is rotatably connected to the rotatably mounted shaft 5 at the third connection point 9.

[0076] In the following, the position of the toggle lever or the actuator shown in Fig. 8 is referred to as the end position (see also Fig. 1 and Fig. 6).

[0077] The position of the toggle lever or actuator shown in Fig. 10 is referred to below as the initial position (see also Fig. 5).

[0078] Fig. 9 shows a position between the initial and final positions, hereinafter referred to as the middle position of the toggle lever or actuator.

[0079] In Fig. 8 (Fig. 2, left), the toggle lever or actuator is shown in the aforementioned end position. This end position (see also Fig. 1 and Fig. 6) also corresponds to position P1 in Fig.

[0080] 1 . When approaching the end position - coming from the direction of a middle position - the uniform movement of the spindle along the movement axis 41 with a constant, maximum available force of the spindle 50 in the direction of movement leads to an increasingly smaller and slower rotation of the shaft 5 relative to its bearing and the load to be actuated with an ever higher, maximum available torque on the shaft 5. This applies to both directions of movement of the spindle along its movement axis 41, both - as previously described - coming from a middle position towards the end position, as well as starting from the end position towards a middle position, when retracting the spindle 50 towards the linear drive 2.

[0081] In other words, in order to achieve a relatively high torque on the shaft 5 while accepting an ever smaller and slower rotation of the shaft 5 over only a few angular degrees, in the area of ​​the end position (Fig. 8, Fig. 2, left) only a relatively low spindle force or only a minimal drive torque of the spindle nut 72 of the linear drive 2 with an increased spindle travel is required - compared to the initial position (Fig. 10, Fig. 2, right) or a middle position (Fig. 9).

[0082] Due to the toggle lever kinematics used in this actuator concept - coming from the initial position (Fig. 10) or a middle position (Fig. 9) - with a constant, constant drive torque of the linear drive 2 or the spindle nut 71 of the spindle drive 70 and thus with a constant, constant force of the spindle 50 in the direction of movement, when approaching or reaching the end position (Fig. 1, Fig. 6, Fig. 8) of the toggle lever mechanism, an actuating torque on the shaft 5 which in principle tends towards infinity results, which can lead to damage to the load to be actuated by means of the actuating element 60 or to parts of the actuator itself.

[0083] The actuating torque on shaft 5, which in principle tends towards infinity, results when spindle 50 is extended far enough that coupling element 6 is preferably arranged perpendicular to the linear movement axis 41 of linear drive 2 and lever 4, in turn, is preferably aligned perpendicular to coupling element 6 (facing actuator 2) and lever 4 is parallel to movement axis 41. This toggle lever position is also shown in Fig. 2, on the left at the second end point 22. The coupling element 6 is aligned perpendicular to lever 4 and to the movement axis 41 of spindle 50 of linear drive 2 and lever 4 is parallel to movement axis 41.

[0084] Since an actuating torque on the shaft 5 which in principle tends towards infinity is not desired and the increased spindle travel - with uniform movement of the spindle - increases the running time, the approach to the position in the second end point 22 is generally not fully completed, but - as shown in Fig. 8 - the above-mentioned end position is arranged a few angular degrees before reaching the position in the second end point 22 and is generally provided with a stop 31 on the housing, for example for the impact of the spindle 50 (Fig. 6).

[0085] In Fig. 10 (Fig. 2, right) the toggle lever or the actuator is in the above-mentioned initial position. A relatively large drive torque of the spindle nut 72 of the linear drive or a relatively high spindle force is possible and leads to a small actuation torque on shaft 5 at a relatively large angle of rotation of the shaft 5, compared for example with a middle position of the toggle lever.

[0086] When approaching the starting position - coming from the direction of a middle position - the uniform movement of the spindle along the movement axis 41 with a constant, maximum available force of the spindle 50 in the direction of movement leads to an increasingly larger and faster rotation of the shaft 5 over a few angular degrees relative to its bearing and the load to be actuated, with an ever smaller, maximum available torque on the shaft 5. This applies to both directions of movement of the spindle along its movement axis 41, both - as previously described - coming from a middle position towards the starting position, and also starting from the starting position towards a middle position, when the spindle 50 extends away from the linear drive 2.

[0087] In other words, in order to achieve a relatively large and relatively fast rotation of the shaft 5 while accepting an ever-decreasing torque on the shaft 5, in the area of ​​the initial position (Fig. 8, Fig. 2, left) - in both directions - an increased spindle force or increased drive torque of the spindle nut 72 of the linear drive 2 with a smaller spindle travel is permissible compared to the end position or a middle position.

[0088] The initial position (Fig. 10) is achieved when the spindle 50 is retracted until the coupling element 6 is pulled approximately parallel to the movement axis 41 of the spindle 50 and the lever 4 is pivoted to its maximum. This toggle lever position is also shown in Fig. 2, on the right at the first end point 21. The coupling element 6 is aligned parallel to the movement axis 41 of the linear drive 2 and perpendicular to the lever 4.

[0089] Frequently, the approach to the position at the first end point 21 is not fully completed, for example due to the increased spindle force, but - as shown in Fig. 10 - the above-mentioned initial position is arranged a few angular degrees before reaching the position at the first end point 21 and is generally provided with a stop 30 on the housing, for example for the impact of the lever 40 (Fig. 5). Fig. 9 shows the actuator in a middle position of the toggle lever between the end position (Fig. 8) and the initial position (Fig. 10). The spindle nut 72 of the linear drive 2 is actuated with a lower drive torque than in the initial position and with a higher drive torque than in the end position.

[0090] The inventive solution to the problem is to limit the force of the spindle along the movement axis 41 in the direction of movement and thus to limit the drive torque of the spindle nut 71 and thus of the spindle drive, for example an electric motor of the linear drive 2. This limitation should take place as a function of the position of the actuator, i.e. as a function of the transmission of the toggle lever, i.e. as a function of the position of the toggle lever or as a function of the spindle position, for example the position of the on the movement axis 41.

[0091] According to the invention, it is proposed to vary the drive torque of the energy converter, for example an electric motor for driving the spindle nut 72 of the linear drive 2, depending on the transmission ratio of the toggle lever mechanism predetermined by the kinematics, wherein in particular a reduction in the direction of the end position (Fig. 1, Fig. 6, Fig. 8) is provided so that no overload occurs.

[0092] This can be achieved directly dependent on the transmission ratio of lever 50, which requires active braking when moving toward the end position shortly before reaching the end position (Fig. 1, Fig. 6, Fig. 8) to compensate for actuator inertia. Active braking can also be provided when moving toward the initial position shortly before reaching the initial position. In this way, maximum system dynamics could be achieved if required, depending on the application.

[0093] This can also be achieved by incorporating the (known) inertias, so that overloading is prevented even in the event of a power failure in any condition (maximum safety). Depending on the downstream load to be actuated, the torque reduction according to the invention can also be provided in only one direction of movement. This is the case, for example, if actuation is against an elastic element, such as a spring, in one direction of actuation, so that avoidable potential damage can be largely eliminated.

[0094] The exact value of a limit depends on many factors related to the actuator as well as the load to be actuated and must therefore be left to the expert in the specific case. For example, the simple size of the actuator as well as the precise dimensioning of the actuator are important, for example, how the angle between the movement axis 41 of the spindle 50 and the extension direction 57 of the coupling element 6 (Fig. 1) is selected in the end position.

[0095] In this way, the actuator can also be referenced, for example the spindle position, at one or both stops (30, 31), without wearing out or even destroying the actuator due to excessive torques or forces.

[0096] It is proposed to use a linear actuator 2 as the base actuator, e.g. an electromechanical spindle actuator 1 with a rotating, rotor-fixed nut 71 and a linearly movable spindle 50, to which a toggle lever mechanism is connected.

[0097] For this purpose, the end of the spindle 50 is articulated to a coupling element 6, which is articulated at its other end to the end of a drive lever 4. The drive lever 4, in turn, is connected at its bearing point to an actuating shaft 5, to which it transmits its torque. The actuating shaft 5 extends out of the actuator housing 40 and can be used to control an actuating function. The coupling element 6 can preferably be designed in two parts on either side of the spindle 50 in order to be able to transmit the forces symmetrically. The end of the spindle 50 is further connected to a bearing element supported in the housing 40. This bearing element preferably consists of two rollers, which are arranged around the joint, preferably on either side of the end of the spindle 50, and which are supported on corresponding support surfaces 44, e.g. in the actuator housing 40, and can roll there in order to improve efficiency.A single- or double-sided plain bearing is conceivable. The support surfaces 44 preferably run parallel to the movement axis 41 of the linearly displaceable spindle 50 of the linear actuator 2, i.e., parallel to the spindle axis.

[0098] Thus, upon actuation, for example, upon retraction of the linear actuating element, i.e., the spindle 50, the coupling element 6 is pivoted, so that this in turn rotates the lever 4. This can occur until the coupling element 6 has been pulled approximately parallel to the movement axis 41 and the lever 4 has pivoted to its maximum. The return stroke occurs analogously.

[0099] This toggle lever mechanism creates a non-linear characteristic curve between the spindle travel and the rotation of the lever 4, or between the spindle force and the torque of the lever 4. Thus, such an actuator according to the invention is particularly suitable for actuating loads that also have a non-linear actuation force characteristic curve. One example is a parking lock actuation. This arrangement allows the actuation axis 5 to be positioned very close to the actuator 1—significantly closer than if a comparably large actuation torque had to be generated solely by an actuation lever, since the actuator itself would then have to be positioned far outside the rotary actuation point, resulting in unfavorable installation space requirements.

[0100] Thus, an actuator with an actuating mechanism is described that can provide a high leverage, yet is located close to the actuating point. The method according to the invention limits the torque strength, preventing damage to the actuator or the device being actuated.

[0101] List of reference symbols

[0102] Actuator

[0103] Linear drive

[0104] Gearbox

[0105] lever

[0106] Shaft , 6' Coupling element a Partial coupling element first connection point second connection point first lever end 0 third connection point 1 second lever end 0, 20' Path curve 1 , 21' first end point 2, 22' second end point 3, 23' first rotational movement 4, 24' second rotational movement 5, 25' first swivel movement 6, 26' second swivel movement 0 first stop 1 second stop 0 Actuator housing 1 Movement axis 2 Contour 3 Bearing element 4 Support surfaces 0 Spindle 1 End cap 2 Support roller 3 Hole 4 Internal toothing 55 External toothing

[0107] 56 Shaft axis

[0108] 57 Direction of extension

[0109] 60 Actuating element

[0110] 61 direction

[0111] 70 spindle drive

[0112] 71 mother

[0113] 72 Gearing point

[0114] 73 rotor bearings

[0115] 74 Rotor

[0116] 75 electric motor

[0117] 80 End position of the actuator or gear

[0118] 90 middle position of the actuator or gear

[0119] 100 Initial position of the actuator or gear

[0120] P1 , P2 spindle positions

Claims

Patent claims 1 . Method for the safe operation of an actuator (1), wherein the actuator is provided with a linear drive (2) and a gear (3) for converting a linear movement into a rotary movement of a shaft (5), wherein the gear (3) comprises a lever (4) which drives the shaft (5) to be subjected to the torque, wherein the gear (3) further comprises a coupling element (6) and wherein the coupling element (6) is connected to the linear drive (2) via a first connection point (7) and to the lever (4) via a second connection point (8), so that energy is transferred between the linear drive (2) and the lever (4) exclusively via the coupling element (6), and wherein the coupling element (6) is rotatably connected in both connection points (7, 8), characterized in that the maximum force provided by the linear drive (2) is limited as a function of a current value of a gear ratio of the gear (3).

2. Method according to claim 1, characterized in that the lever (4) is connected at a second lever end (11) via a third connection point (10) in a rotationally fixed manner to the shaft (5) and at a first lever end (9) is rotatably connected via the second connection point (8) to the coupling element (6) and the coupling element (6) is rotatably connected via the first connection point (7) to the linear drive (2) and the lever (4) establishes a rigid connection between the two connection points (8, 10).

3. Method according to claim 1 or 2, characterized in that in an initial position (100) of the gear (3) a first, preferably housing-fixed stop (30) is provided for fixing the initial position (100) and / or in an end position (80) of the gear (3) a second, preferably housing-fixed stop (31) is provided for fixing the end position (80), and wherein the first lever end (9) is designed for abutting the lever (4) against the first and / or second stop (30, 31).

4. Method according to claim 1 or 2, characterized in that in an end position (80) of the gear (3) a second, preferably housing-fixed stop (31) is provided for fixing the end position (80), and wherein a spindle end or an end cap (51) of a spindle (50) of the linear drive (2) is designed to stop the spindle (50) against the second stop (31).

5. Method according to one of the preceding claims, characterized in that the value of the gear ratio at a travel position along the movement axis (41) of the linear drive (2) is calculated from the ratio of a rotation angle Arp to be determined, which results from the rotational movement of the shaft (5) resulting from the movement of the linear drive (2), and a predetermined distance Ax, which the linear drive (2) moves along the movement axis (41) of the linear drive (2), starting from the travel position.

6. Method according to one of the preceding claims, characterized in that the course of the values ​​of the gear ratio is stored as a function of the travel position of the linear drive (2).

7. Method according to one of the preceding claims, characterized in that the dependence of the values ​​of the gear ratio on the travel position of the linear drive (2) is not linear.

8. Method according to one of the preceding claims, characterized in that the end position (80) has a predetermined end position threshold value for the gear ratio.

9. Method according to one of the preceding claims, characterized in that the force of the linear drive (2) along the movement axis (41) of the linear drive (2) is limited when the direction of movement of the linear drive (2) is towards the end position (80) and the gear ratio at the current position exceeds the end position threshold value.

10. Method according to claim 8, characterized in that the limitation stops the linear drive (2).

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