Methods for the safe operation of actuators

Abstract

The present invention relates to a method for the safe operation of an actuator (1). The actuator comprises a linear drive (2) and a gear unit (3) configured to provide torque and convert linear motion of a shaft (5) into rotational motion, the gear unit (3) comprising a lever (4) that rotationally drives the shaft (5) to which torque is applied, the gear unit (3) also having a coupling element (6), the coupling element (6) connected to the linear drive (2) via a first connection point (7) and to the lever (4) via a second connection point (8), thereby transmitting energy exclusively between the linear drive (2) and the lever (4) via the coupling element (6), the coupling element (6) being rotatably connected at both connection points (7, 8). According to the present invention, the maximum force provided by the linear drive (2) is limited according to the current value of the gear ratio of the gear unit (3).

Description

Technical Field

[0001] The present invention relates to a method for the safe operation of an actuator having the features according to the preamble of claim 1.

Background Art

[0002] Such an actuator is already known from German Patent Application Publication No. 102016207827 together with a non-linear actuating force for an operating unit for an automatic transmission of a motor vehicle (preferably a PRND automatic transmission system). For this purpose, a corresponding slide track is provided to generate non-linearity.

[0003] Generally, such an actuator is already known from German Patent Application Publication No. 102018116133.

[0004] In the applicant's unpublished German patent application having application number 102023115292.0, an actuator having a non-linear characteristic curve is likewise disclosed. Due to the kinematics of the toggle lever used in the concept of this actuator, a constant drive torque of an electric motor at one end position of the toggle lever mechanism (FIG. 1, FIG. 8) results in an actuating force (torque) at the output shaft (5), which, in principle, tends towards infinity and thus can lead to damage to the load to be actuated or the components of the actuator itself.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention addresses the problem of operating such an actuator safely in a simple manner.

Means for Solving the Problems

[0006] This problem addressed by the present invention is solved by a method having the features of claim 1.

[0007] Accordingly, a method for the safe operation of an actuator is provided, comprising a linear drive and a gear mechanism configured to provide torque and convert linear motion of a shaft into rotational motion, the gear mechanism comprising a lever that rotationally drives the shaft to which torque is applied, the gear mechanism further comprising a coupling element, the coupling element connected to the linear drive via a first connection point and to the lever via a second connection point, thereby allowing energy transfer between the linear drive and the lever exclusively through the coupling element, the coupling element being rotatably connected at both connection points. According to the method, the maximum force provided by the linear drive is limited according to the current value of the gear ratio of the gear mechanism.

[0008] The current gear ratio of a gear system is determined by the movement position of the linear drive, for example, the spindle of a spindle drive, along the moving axis, and is either already learned at the end of the line or redefined by a reference or update procedure. Therefore, the current gear ratio is the gear ratio value at the current movement position.

[0009] In a preferred embodiment of the present invention, the lever is provided to be rotatably fixed to a shaft at a second lever end via a third connection point, rotatably connected to a coupling element at a first lever end via a second connection point, the coupling element rotatably connected to a linear drive via a first connection point, and the lever establishes a rigid connection between the two connection points.

[0010] In a more preferred embodiment of the present invention, a first stop is provided to fix the initial position of the gear system, preferably fixed to the housing, and / or a second stop is provided to fix the final position of the gear system, preferably fixed to the housing, and a first lever end is configured to bring the lever into contact with the first and / or second stop.

[0011] In an alternative preferred embodiment of the present invention, a second stop, preferably fixed to the housing, is provided at the final position of the gear system to fix the final position, and the spindle end or end cap of the linear drive spindle is configured to stop the spindle relative to the second stop.

[0012] In a more preferred embodiment of the present invention, the gear ratio value at a moving position along the moving axis of the linear drive is calculated from the ratio Δφ of the rotation angle to be determined, which is obtained from the rotational movement of the shaft obtained from the movement of the linear drive and a predetermined distance Δx over which the linear drive moves along the moving axis of the linear drive starting from the moving position.

[0013] The current moving position is the position between the initial position and the final position where a predetermined point on the spindle, such as the spindle center, spindle end, or the end cap of a linear drive spindle, is currently located during the spindle's movement.

[0014] A given spindle feed, for example, denoted as Δx, leads to a determined rotation of the shaft, for example, denoted as Δφ. The translation is calculated as the quotient of both values, Δφ / Δx.

[0015] Due to the nonlinearity of translation in the kinematics of a toggle lever, the translation is not the same along the entire path between the initial and final positions, but takes different values ​​at each position between the initial and final positions. For each movement position between the initial and final positions, the gear ratio value at that position is determined as the quotient Δφ / Δx. This is mainly done at the end of the line, but may also be required by higher-order control methods as needed or periodically.

[0016] In a more preferred embodiment of the present invention, the gear ratio value is stored according to the movement position of the linear drive.

[0017] In a more preferred embodiment of the present invention, the dependence of the gear ratio value on the moving position of the linear drive is not linear.

[0018] In a more preferred embodiment of the present invention, the final position has a predetermined final position threshold with respect to the gear ratio.

[0019] In a particularly preferred embodiment of the present invention, when the direction of movement of the linear drive is toward the final position and the gear ratio at the current position exceeds the final position threshold, the force of the linear drive is limited along the axis of movement of the linear drive.

[0020] In a preferred embodiment of the present invention, this limitation causes the linear drive to stop.

[0021] Therefore, a linear drive, such as a spindle, can be advantageously stopped in a targeted manner just before reaching the stop, so that the actuator arrives at the stop position just before actually reaching the final position. Thus, the actual final position can be selected such that the stop position, i.e., the actual stopping position, is also, for example, the actual desired stopping position just before reaching the final position or stop. In this way, not only can the desired stopping position be reached, but the stopping position can also be avoided as desired, and thus it is possible to prevent collision with the end stop or movement of the actuator or load due to overload.

[0022] According to the present invention, it is proposed to vary the driving torque of an energy converter, such as an electric motor, in order to drive the spindle nut of a linear drive in accordance with the translation of a toggle lever mechanism determined by kinematics, and in particular, a reduction in the direction of the final position (Figures 1, 6, and 8) is provided so as not to cause overload.

[0023] This can be done directly in response to the translation of the toggle lever, and in the case of movement towards the final position, active braking is required immediately before reaching the final position (Figures 1, 6, 8) in order to compensate for the inertia of the actuator. During active braking, the drive part of the linear actuator generates braking torque by reversing the current if necessary. Active braking can also be provided for movement towards the initial position immediately before reaching the initial position. Thus, depending on the intended application, the maximum system dynamics can also be presented as required.

[0024] When maximum safety is required, the possibility of a power failure in the actuator may also be taken into account. For example, it is a scenario where a power failure occurs just when braking torque is required. Taking into account the known inertia, only the braking torque without any current is considered, and the drive part is turned off earlier in the direction of the final position before reaching the final position than when an increased braking torque can be provided by reversing the current. Thus, an overload due to the kinematics of the load being actuated or the toggle lever of the actuator itself can be prevented in any state of the actuator.

[0025] Depending on the downstream load being actuated, the torque reduction according to the invention can also be provided in only one direction of movement. This is, for example, a case where the actuation occurs in a direction that resists elasticity such as a spring, thereby almost eliminating potential damage to be avoided.

[0026] In addition to the lever and the linear drive, a coupling element can provide a third component connecting them, and the coupling element can be mounted in a particularly simple manner, enabling the non-linear characteristic curve of the actuator by corresponding energy transfer from the linear drive to the lever and thus to the shaft.

[0027] Furthermore, the lever may be connected to the shaft via a third connection point in a rotatably fixed manner at the first lever, and to the coupling element via a second connection point in a rotatably fixed manner at the second lever, and the lever may also establish a rigid connection between the two connection points. Although the distance from the shaft to the end of the second lever cannot be varied, the transmitted torque or the corresponding rotational speed can be varied exclusively, so the nonlinearity of the actuator can be easily adapted by adapting the position of the connection point and the length of the coupling element. In other words, the movement of the lever in space is defined by the position of the third connection point, which acts as a constraint fixed to the housing, and the rotational speed and torque of the shaft are determined in conjunction with the length of the coupling element and its position on the linear drive.

[0028] According to the present invention, the coupling element can establish a rigid connection between the first and second connection points, thereby causing a linear movement of the first connection point by a linear drive to result in a first pivotal movement of the second connection point around the first connection point, and a second pivotal movement of the second connection point around the third connection point. Thus, the rotation of the shaft is caused by the second pivotal movement due to the rotationally fixed connection of the lever to the shaft. The distance the second connection point moves is predetermined by the constraints of the rigid lever. The nonlinearity of the rotational speed or transmitted torque is appropriately predetermined by the corresponding superposition of the two pivots on a fixed predetermined curve.

[0029] The coupling element can connect the lever and the linear drive in such a way that the second connection point moves along an orbit. Thereby, in a first working area around the first end point of the orbit, the movement of the first connection point is stepped up by the linear drive to a first rotational movement of the shaft, and in a second working area around the second end point, the movement of the first connection point is stepped down by the linear drive to a second rotational movement of the shaft. The first rotational movement covers a larger angular range with a smaller force transmission than the second rotational movement within a certain time interval. Thus, specific operating points and intermediate transition regions for the operating force of the shaft can be defined, which correspond to the desired non-linearity of the operation and transition to each other.

[0030] Also, at the second end point, it is possible for the coupling element to be oriented perpendicular to the lever and also to the movement axis of the linear drive, and the lever is parallel to the movement axis. Force transmission is difficult in such an arrangement. The force acting from the linear drive on the coupling element thus acts perpendicular to the tangent of the arc described by the second lever end, and only a very small torque is transmitted, so that a high rotational speed can be achieved. In this arrangement, the actuator is also self-locking. This is more applicable when the friction points of the actuator are taken into account.

[0031] In a second possible arrangement, at the first end point, the coupling element can be aligned parallel to the movement axis of the linear drive and perpendicular to the lever. This results in maximum torque and minimum rotational speed. Thus, in this case, the position of the actuator is also stable.

[0032] Preferably, a first stop is provided at the first endpoint to fix the first endpoint, and / or, preferably, a second stop is provided at the second endpoint to fix the second endpoint, and the second lever end is configured such that the lever strikes the first and / or second stop. In this way, two stable endpoints of the actuator can be safely moved and held against vibration.

[0033] The stopper can be provided on the extension of the linear drive spindle on the actuator housing, or as a stopper for the lever at the opposite end position.

[0034] The first and / or second stop units can be integrally formed from the actuator housing.

[0035] Instead of limiting the linear adjustability of the linear drive within the linear drive, the advantage of positioning the stop on the housing is that, in further development, the rotor bearing of the linear drive is positioned between the linear drive and the lever, and therefore the accumulated friction coefficient, which is determined mainly by the sliding friction coefficient within the linear drive and the stop and negligibly determined only by the rolling friction coefficient of the rotor bearing, does not vary as much as the combination of sliding friction points. This makes it possible to define the required driving torque of the linear drive more precisely, which is necessary to ensure safe vibration damping at the stop.

[0036] A method for safely preventing an actuator from vibrating at its endpoints consists of slow / decelerating movement of the linear drive into a rest area. This means, for example, that the spindle of the linear drive is moved relative to one rest area, and / or the lever is moved relative to the other rest area. As the process continues, the linear drive continues to move in the same direction, or the corresponding spindle continues to rotate even after reaching its respective rest area, and the linear drive, spindle, or lever is moved with a defined torque that is safely below the maximum possible torque of the motor or electric motor driving the linear drive or spindle. This ensures that the vibration can be safely released to allow the actuator to return to a normal operating state even when boundary conditions (fluctuations such as lubrication, temperature, and power supply) change.

[0037] The first and / or second stops can have a certain degree of softness so that a predetermined linear movement of the linear drive is possible, in order to allow movement relative to the stops in a specific controlled manner for adjusting or calibrating the actuator.

[0038] The required locking torque can also be predetermined to a reasonable value within the configuration, through the stopping point for the spindle or lever, or the effective radius of their modified forms.

[0039] No additional components are required for the stop section; only the geometric shape of the actuator housing needs to be adapted, allowing for near cost-neutral fixing of the end stop section.

[0040] An actuator comprehensively comprises a linear drive and gear mechanism to convert linear motion into rotational motion. In principle, those skilled in the art are well aware of the various types of linear drives, which are mechanical or hydraulic linear drives based on different principles. A linear drive can be formed, for example, by a ball screw drive or a planetary roller screw drive. Linear motion can be provided by a nut on a spindle or by the spindle itself. Rotational motion of the shaft is generated by a lever connected to the shaft in a rotationally fixed manner. A coupling element establishes a rigid connection between the lever of the linear drive and the linear motion element (such as a nut or spindle). This means that the connection point of the coupling element on the linear drive moves linearly exclusively along a straight path, and the connection point of the coupling element on the lever pivots exclusively along a circular path with a predetermined radius r around the axis of the shaft, but the distance between the two connection points on the lever and the linear drive remains constant. In this way, a trajectory of the second connection point on the lever is realized that drives the shaft by providing a higher angular velocity with lower torque in the first working region and a lower angular velocity with higher torque in the second working region. There is a corresponding transition region between the two working regions.

[0041] Thus, the shaft can provide rotational motion with a variable characteristic curve, namely, having a greater angular velocity in a first angular range than in a second angular range, and correspondingly, having a smaller torque in the first angular range than in the second angular range. This rotational motion can be used to actuate isolation units, clutches, brakes, or parking locks in the drive train of an automobile or commercial vehicle.

[0042] The toggle lever mechanism described herein creates a nonlinear characteristic curve between the linear advance of a linear drive, e.g., spindle movement, the rotation of the lever or the driving force of the linear drive, i.e., the spindle force, and the torque of the lever. Therefore, such actuators are particularly suitable for acting on loads that also have a nonlinear operating force characteristic curve. One example of this would be the operation of a parking lock.

[0043] This arrangement allows the shaft to actuate a load that is positioned very close to the linear drive, significantly closer than when an equally large operating torque is generated solely by the operating lever.

[0044] Exemplary embodiments of the method according to the present invention, which are not limited thereto and may bring about further features according to the present invention, are shown in Figures 8, 9, and 10. [Brief explanation of the drawing]

[0045] [Figure 1] The actuator is shown in a partial cross-sectional view. [Figure 2] Figure 1 shows a symbolic representation of the trajectory of the second connection point 8 of the lever 4 for operating the actuator shaft 5. [Figure 3] An alternative actuator configuration is shown. [Figure 4] Figure 3 shows a symbolic representation of the alternative trajectory of the second connection point 8 of the lever 4 for operating the actuator shaft 5. [Figure 5] Figure 1 shows an additional stop section (second connection point 8 of the first endpoint 21) on the actuator housing of the actuator. [Figure 6] Figure 1 shows an additional stop point (second connection point 8 of the second endpoint 22) on the actuator housing of the actuator (near endpoint 22: maximum torque on the shaft 5 during movement of the spindle 50 toward or away from endpoint 22). [Figure 7]This shows half of the actuator housing. [Figure 8] Description of the method according to the present invention: The actuator is shown in the final position of the toggle lever (Figure 8 is identical to Figure 1, but does not have reference numerals). [Figure 9] Description of the method according to the present invention: Figure 8 shows the actuator in the intermediate position of the toggle lever. [Figure 10] Description of the method according to the present invention: Figure 8 shows the actuator in the initial position of the toggle lever. [Modes for carrying out the invention]

[0046] Figure 1 shows the actuator 1 for converting the linear motion of the linear drive 2 into the rotational motion 23 and 24 of the shaft 5.

[0047] The linear drive 2 includes a spindle 50 for this purpose. The spindle 50 has an end cap 51 which is connected to the coupling element 6 via a support roller 52 on one side. As shown here, instead of just one support roller 52 on one side, support rollers on both sides can also be connected to their respective coupling elements.

[0048] The support roller 52 represents a first connection point 7 for the rotatable mounting of the coupling element 6.

[0049] The coupling element 6 is configured as a linearly extending rigid sheet metal component, which is connected to the spindle 50 at one end via a first connection point 7 and to the lever 4 at a second end via a second connection point 8. The coupling element 6 is also rotatably mounted on the lever 4 via the second connection point 8.

[0050] Lever 4 extends from its first lever end 9, which has a second connection point 8, to a third connection point 10 at the second lever end 11. At the third connection point 10, lever 4 is connected to shaft 5 in a rotatably fixed manner. For this purpose, lever 4 has a hole 53 with internal teeth 54. Shaft 5 has corresponding external teeth 55 that engage with the internal teeth 54. Shaft 5 is rotatably mounted within actuator housing 40 and extends through actuator housing 40 in the direction of shaft axis 56. Shaft axis 56 extends perpendicular to both the moving axis 41 of spindle 50 and the extension direction 57 of coupling element 6.

[0051] Outside the actuator housing 40, the shaft 5 is connected to the actuation element 60. This can be an eccentric disc, a contoured disc, etc., which is set to rotate by the shaft 5. A parking lock, brake, clutch, etc., can be actuated via this actuation element 60.

[0052] The spindle 50, end cap 51, coupling element 6, and lever 4 are components of the gear device 3, and they convert the linear movement of the spindle 50 of the linear drive 2 into the rotational movement 23 and 24 of the shaft 5 to drive the actuation element 60.

[0053] In Figure 1, the spindle 50 is located at position P1, so that the extension direction 57 of the coupling element 6 is substantially perpendicular to the movement axis 41 of the spindle 50 and to the lever 4. At position P1, the spindle 50 is substantially fully extended, and the second connection point 8 is located at the second endpoint 22. When the spindle 50 is retracted, the corresponding travel path of the spindle 50 is coupled via the coupling element 6 to a shorter travel path of the second connection point 8 which is perpendicular to it. In other words, in this case, the linear movement of the linear drive 2 is converted to a second rotational movement 24. The maximum torque is transmitted to the shaft 5 at the minimum rotational speed.

[0054] A diagram of the transmitted torque and associated rotational speed is shown in Figure 2. The second connection point 8 is located at the second endpoint 22 in the left portion of Figure 2 and at the first endpoint 21 in the right portion, as also shown in Figure 1. At the second endpoint 22 of the second connection point 8, the first connection point 7 of the coupling element 6 is located on the moving axis 41 of the spindle 50. The linear movement to retract the spindle 50 in direction 61 pulls the lever 4 through the second connection point 8 into a second rotational movement 24 around the third connection point 10. The second connection point 8 follows the trajectory 20 at a distance r between the second connection point 8 and the third connection point 10. This movement of the lever 4 is characterized by the minimum rotational speed and maximum torque at the second endpoint 22.

[0055] In the right-hand portion of Figure 2, the second connection point 8 is located at the first endpoint 21. In this case, the spindle 50 is retracted until the lever element 4 is substantially perfectly parallel to the spindle 50 on the moving axis 41. Then, by extending the spindle 50, the maximum rotational speed and minimum torque of the lever 4 are obtained.

[0056] In the region between the two endpoints 21 and 22, the lever 4 is therefore driven by a nonlinear torque characteristic curve. The shaft 5 is driven as appropriate, and the nonlinear characteristic curve of the shaft 5 can be used to actuate a nonlinear load such as a parking lock.

[0057] Figure 3 shows an alternative arrangement of the coupling element 6 between the lever 4 and the spindle 50. In this case, the spindle 50 is in the stowed position P2, and the second connection point 8 is then located at the second endpoint 22. In the parallel position of the coupling element 6, it is positioned to cover the spindle 50 in the direction of the movement axis 41. In contrast to the embodiments of Figures 1 and 2, the coupling element 6 is tilted by 90°.

[0058] A diagram of the torque generated by this actuator can be found in Figure 4. In this case, the first endpoint 21 of the second connection point 8 is shown on the left, and therefore the second endpoint 22 is shown on the right. In between, the second connection point 8 is moved along the trajectory 20'. In this case as well, the maximum torque is transmitted at the second endpoint 22 (right), and the minimum torque is transmitted to the shaft 50 at the first endpoint 21. Thus, the shaft 50 receives a first rotational movement 23 at the first endpoint 21 and a second rotational movement 24 at the second endpoint 22. The lengths of the arrows for rotational movements 23 and 24 symbolize the transmitted torque.

[0059] The trajectories 20 and 20' in the two alternative examples in Figures 2 and 4 are substantially mirror images and otherwise indistinguishable. However, the direction of rotation is reversed at the minimum and maximum torque of shaft 5; that is, in each case, the rotational movements 23 and 24' are reversed and of equal magnitude. In the first example in Figure 2, the maximum torque is transmitted when the spindle 50 is retracted, and in the second alternative example in Figure 4, it is transmitted when the spindle 50 is extended.

[0060] An alternative embodiment of the actuator 1 according to Figure 1, as shown in Figure 3, also has a coupling element 6' on both sides of the spindle 50, having two parallel partial coupling elements 6a. Such a coupling element 6' then also enables operation according to the alternative example from Figure 4.

[0061] However, the same applies in this case to the generation of the nonlinear characteristic curve of shaft 5, as already shown in Figure 1.

[0062] Figures 5 and 6 show the actuator according to Figure 1, where the drive is shown in a cross-sectional view by a spindle drive, and the stoppers 30 and 31 for the lever 4 and spindle 50, respectively, are also provided on the actuator housing 40.

[0063] In Figure 5, the lever 4, i.e., the second connection point 8, is located at the first endpoint 21, while in Figure 6, the second connection point 8 is shown at the second endpoint 22. In Figure 6, the maximum torque is generated on the shaft 5 when the spindle 50 is retracted in the direction of the linear drive 2.

[0064] In Figure 5, the lever 4 is positioned at the first endpoint 21 of the first stop 30. The first stop 30 is configured as an integrated component of the actuator housing 40. Here, when a predetermined torque is applied by the spindle 50 or the spindle drive 70, and that torque presses the lever 4 or the first lever end 9 with a predetermined stopping force against the first stop 30, the position of the lever 4, and therefore the angular position of the shaft 5, can be clearly set, and the actuator 1 can generally be fixed against adjustment by, for example, vibration.

[0065] In Figure 6, the lever 4, or the second connection point 8, is located at the second endpoint 22. The second stop 31 is provided here for the spindle 50, or the end cap 51 of the spindle 50. Similarly, the spindle 50 can be pushed down against the second stop 31 with a predetermined torque. In this case as well, the position of the lever 4, and therefore the angular position of the shaft 5, can be clearly set, and the actuator 1 can generally be fixed against adjustment by, for example, vibration.

[0066] Figures 5 and 6 further show that the spindle 50 is driven via a nut 71, which is connected to the spindle via a toothed point 72. Since the spindle 50 is received in the actuator housing 40 in a rotationally fixed manner, the rotational movement of the nut 71 is thus converted into linear movement of the spindle 50. The spindle 50 is supported on the actuator housing 40 via the nut 71 and the rotor bearing 73. The driving of the nut 71 is achieved via the rotor 74 of an electric motor 75.

[0067] As shown here, the rotor bearing 73 is axially positioned between the stoppers 30, 31 and the rotor 74, and the accumulated friction coefficient, which is determined mainly by the sliding friction coefficient (spindle / nut, stopper surface) and negligibly determined only by the rolling friction coefficient of the rotor bearing, does not vary as much as the combination of sliding friction points, so that the torque required to safely prevent the lever 4 or spindle 50 from swaying in the first or second stoppers 30, 31 can be set more precisely.

[0068] Figure 7 shows half of the actuator housing 40.

[0069] The actuator housing 40 has an inner 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 is located at one end of the spindle 50, as shown in Figure 1, and supports the spindle 50 on the actuator housing 40. It is preferably configured as support rollers 52, as shown in Figure 1. The bearing element 43 coincides with a first connection point 7. Preferably, this bearing element 43 consists of two support rollers 52, preferably located on both sides of the end of the spindle 50, around the articulated first connection point 7 between the spindle 50 and the coupling element 6, and supported on corresponding frame-fixed support surfaces 44 of the contour 42 within the actuator housing 40, on which it can roll. In this way, the efficiency of the actuator 1 can be improved (in principle, single-sided or double-sided sliding bearings are also conceivable). The support surface 44 preferably extends parallel to the moving axis 41 of the spindle 50 or to the linearly displaceable element of the linear drive 2.

[0070] Using the actuator 1 shown herein, which follows the principle of a toggle lever, a nonlinear operating characteristic curve can therefore be easily realized on the operating element 60 via the linear drive 2. The provided stop units 30 and 31 can be used to prevent unintended adjustments due to vibrations, and to ensure that the defined position of the actuator 1 is maintained, for example, in the event of a power outage.

[0071] Efficient and safe operation can be achieved through the support surface 44 in conjunction with the support roller 52.

[0072] Therefore, the toggle lever mechanism is derived from the spindle 50, coupling element 6, lever 4, and shaft 5. The end of the spindle 50 is rotatably connected to one end of the coupling element 6 at the first connection point 7. The other end of the connecting element 6 is rotatably connected to one end 9 of the lever 4 at the second connection point 8. The other end 11 of the lever 4 is connected to a rotatably mounted shaft 5 at a third connection point 9, in a manner that is fixed to rotation.

[0073] Hereafter, the position of the toggle lever or actuator shown in Figure 8 will be referred to as the final position (see also Figures 1 and 6).

[0074] The position of the toggle lever or actuator shown in Figure 10 is referred to as the initial position below (see also Figure 5).

[0075] Figure 9 shows the position between the initial position and the final position, which will be referred to below as the intermediate position of the toggle lever or actuator.

[0076] In Figure 8 (Figure 2, left), the toggle lever or actuator is shown in the final position described above. The final position (see also Figures 1 and 6) also corresponds to position P1 in Figure 1. Coming from the direction of the intermediate position and approaching the final position, the uniform movement of the spindle 50 along the moving axis 41 with a constant maximum available force in the direction of movement leads to increasingly smaller and slower rotations of the shaft 5 relative to the bearing, the load is actuated and there is an even higher maximum available torque on the shaft 5. This applies to both directions of movement of the spindle along the moving axis 41, both coming from the intermediate position and moving towards the final position, as described above, and from the final position towards the intermediate position when the spindle 50 is retracted toward the linear drive 2.

[0077] In other words, compared to the initial position (Figure 10, Figure 2, right) or the intermediate position (Figure 9), achieving a relatively high torque in shaft 5 while accepting smaller and slower rotations of shaft 5 over a range of only a few degrees in both directions means that in the region of the final position (Figure 8, Figure 2, left), only a relatively low spindle force, or the minimum driving torque of the spindle nut 72 of the linear drive 2, is required for the increased spindle movement.

[0078] Starting from an initial position (Figure 10) or an intermediate position (Figure 9), the kinematics of the toggle lever used in this actuator concept, which has a constant driving torque on the spindle nut 71 of the linear drive 2 or spindle drive 70 and therefore a constant force on the spindle 50 in the direction of movement, means that as the toggle lever mechanism approaches or reaches its final position (Figures 1, 6, and 8), the operating torque on the shaft 5 tends to move toward infinity, which can lead to damage to the load actuated using the actuating element 60 or to parts of the actuator itself.

[0079] The operating torque on the shaft 5 tends to be infinite in principle, and the operating torque on the shaft 5 is generated when the spindle 50 and the coupling element 6 are preferably positioned perpendicular to the linear movement axis 41 of the linear drive 2, and the lever 4 is then preferably positioned perpendicular to the coupling element 6 (facing the actuator 2), and the lever 4 is extended to the extent that it is aligned parallel to the movement axis 41. This toggle lever position is to the left of the second endpoint 22, and is also shown in Figure 2. The coupling element 6 is perpendicular to the lever 4 and to the movement axis 41 of the spindle 50 of the linear drive 2, and the lever 4 is aligned parallel to the movement axis 41.

[0080] The operating torque on the shaft 5, which tends to extend indefinitely, is undesirable, and the increased spindle movement increases the operating time when the spindle moves uniformly, so the approach to the position at the second endpoint 22 is usually not completed, but as shown in Figure 8, the aforementioned final position is positioned several times until it reaches the position at the second endpoint 22, and typically includes a stopper 31 on the housing for the spindle 50 to collide with (Figure 6).

[0081] In Figure 10 (Figure 2, right), the toggle lever or actuator is in the initial position described above. A relatively large driving torque or relatively high spindle force is possible for the linear drive spindle nut 72, resulting in a small operating torque on the shaft 5, which has a relatively large rotation angle of the shaft 5 compared to the intermediate position of the toggle lever.

[0082] Coming from the direction of the intermediate position, as the spindle approaches its initial position, the uniform movement of the spindle along the moving axis 41 with a constant maximum available force of the spindle 50 in the direction of movement leads to a larger and faster rotation of the shaft 5 over several degrees relative to the bearing, activating the load and resulting in a lower maximum available torque in the shaft 5. This applies to both directions of movement of the spindle along the moving axis 41, both coming from the intermediate position toward the initial position and extending the spindle 50 away from the linear drive 2 toward the intermediate position.

[0083] In other words, in order to achieve relatively large and relatively high-speed rotation of the shaft 5 while accepting a reduced torque on the shaft 5 compared to the final or intermediate position, an increased spindle force, or an increased driving torque of the spindle nut 72 of the linear drive 2, along with a shorter spindle path, is acceptable in both directions in the initial position region (Figure 8, Figure 2, left).

[0084] The initial position (Figure 10) is achieved when the spindle 50 is retracted, with the coupling element 6 pulled nearly parallel to the spindle 50's axis of movement 41, and the lever 4 pivoted to its maximum extent. This toggle lever position is to the right of the first endpoint 21 and is also shown in Figure 2. The coupling element 6 is aligned parallel to the linear drive 2's axis of movement 41 and perpendicular to the lever 4.

[0085] In many cases, for example, due to increased spindle force, the approach to the position at the first endpoint 21 is not fully completed, but as shown in Figure 10, the initial position described above is moved several times until it reaches the position at the first endpoint 21, and typically includes a stopper 30 on the housing for the lever 40 to collide with (Figure 5).

[0086] Figure 9 shows the actuator in an intermediate position of the toggle lever between the final position (Figure 8) and the initial position (Figure 10). The spindle nut 72 of the linear drive 2 is actuated with a lower drive torque compared to the initial position and a higher drive torque compared to the final position.

[0087] The present invention's solution to the problem is to limit the force on the spindle along the moving axis 41 in the direction of movement, and therefore the driving torque of the spindle nut 71, and consequently the spindle drive, and thus the electric motor of, for example, the linear drive 2. This limiting should be done according to the position of the actuator, i.e., according to the translation of the toggle lever, i.e., according to the position of the toggle lever, or according to the spindle position, for example, the position on the moving axis 41.

[0088] According to the present invention, it is proposed to vary the driving torque of an energy converter, such as an electric motor, in order to drive the spindle nut 72 of the linear drive 2 in accordance with the translation of the toggle lever mechanism determined by kinematics, and in particular, a reduction in the direction of the final position (Figures 1, 6, and 8) is provided so as not to cause overload.

[0089] This can be done directly in response to the translation of lever 50, and in the case of movement toward the final position, active braking is required just before reaching the final position (Figures 1, 6, and 8) to compensate for the actuator's inertia. Active braking can also be provided for movement toward the initial position just before reaching the initial position. In this way, the maximum system dynamics can also be presented as needed, depending on the intended application.

[0090] This can also be achieved (maximum safety) by taking into account (known) inertia so that overload is prevented in any condition, even in the event of a power outage.

[0091] Depending on the downstream load being actuated, the torque reduction according to the present invention can also be provided in only one direction of movement. This is the case, for example, when the actuation occurs in a direction that resists the elasticity of a spring or similar, thereby virtually eliminating the potential damage that would otherwise be avoided.

[0092] The precise value of the limit depends on many characteristics of the actuator, as well as the load being operated, and therefore, in each specific case, it must be left to the person skilled in the art. For example, the simple size of the actuator, as well as its precise dimensions, are important, and the angle between the moving axis 41 of the spindle 50 and the extension direction 57 of the coupling element 6 (Figure 1) at the final position is selected.

[0093] Thus, referencing the spindle position at, for example, one or both of the actuator's stop sections (30, 31) can also be done without exhausting excessive torque or force, or even worse, without damaging the actuator.

[0094] It is proposed to use the linear actuator 2 as a basic actuator, for example, as an electromechanical spindle actuator 1 having a nut 71 for fixing a rotating rotor and a linearly movable spindle 50 to which a toggle lever mechanism is connected.

[0095] For this purpose, one end of the spindle 50 is articulated to a coupling element 6, which at the other end is articulated to the end of the drive lever 4. The drive lever 4 is then connected at its bearing point to an actuation shaft 5 that transmits its torque. The actuation shaft 5 is routed outside the actuator housing 40 and can be used to control the actuation function. The coupling element 6 may preferably consist of two parts on either side of the spindle 50 so as to transmit forces symmetrically.

[0096] The end of the spindle 50 is still connected to a bearing element supported by the housing 40. Preferably, this bearing element is positioned around the coupling, preferably on both sides of the end of the spindle 50, and consists of two rollers that can roll on a corresponding frame-fixed support surface 44 within the actuator housing 40, thereby improving efficiency. A single- or double-sided sliding bearing is possible. The support surface 44 preferably extends parallel to the moving axis 41 of the linearly displaceable spindle 50 of the linear actuator 2, i.e., parallel to the spindle axis.

[0097] Therefore, when activated, for example, when the linear actuation element, i.e., the spindle 50, is retracted, the coupling element 6 is pivoted, thereby causing it to rotate the lever 4. This can be done until the coupling element 6 is pulled nearly parallel to the moving axis 41 and the lever 4 is pivoted to its maximum extent. The return stroke is performed similarly.

[0098] This toggle lever mechanism produces a nonlinear characteristic curve between the movement of the spindle and the rotation of lever 4, or between the spindle force and the torque of lever 4. Therefore, such an actuator is particularly suitable for acting on loads that also have a nonlinear operating force characteristic curve. One example would be the operation of a parking lock.

[0099] This arrangement allows the actuation shaft 5 to be positioned very close to the actuator 1, and significantly closer than when a relatively large actuation torque must be generated solely by the actuation lever, as the actuator itself would need to be positioned away from the rotational actuation point, thereby resulting in undesirable spatial requirements.

[0100] Therefore, an actuator having an operating mechanism that can provide a high leverage ratio but is located near the point of operation is described.

[0101] The method according to the present invention limits the torque intensity so as not to cause damage to the actuator or the device being actuated. [Explanation of symbols]

[0102] 1 Actuator 2 Linear Drive 3. Gear system 4 Lever 5 shafts 6, 6' connecting element 6a partially connected element 7. First connection point 8. Second connection point 9. First lever end 10. Third connection point 11 Second lever end 20, 20' orbit 21, 21' First endpoint 22, 22' Second endpoint 23, 23' First rotational movement 24, 24' Second rotational movement 25, 25' First turning movement 26, 26' Second turning movement 30 First stopping section 31 Second stopping section 40 Actuator Housing 41 Movement axis 42 Outline 43 Bearing elements 44 Support surface 50 spindles 51 End caps 52 Support rollers 53 holes 54 Internal teeth 55 External teeth 56 Shaft axis 57 Extension direction 60 Actuating elements 61 directions 70 Spindle Drive 71 Nut 72 Toothed dots 73 Rotor bearing 74 rotors 75 Electric motor 80 Final position of actuator or gear unit 90 Intermediate position of actuator or gear system 100 Initial position of actuator or gear device P1, P2 spindle positions

Claims

1. A method for the safe operation of an actuator (1) configured to provide torque, comprising a linear drive (2) and a gear unit (3) for converting linear motion of a shaft (5) into rotational motion, wherein the gear unit (3) comprises a lever (4) for rotationally driving the shaft (5) to which the torque is applied, and the gear unit (3) further comprises a coupling element (6), the coupling element (6) being connected to the linear drive (2) via a first connection point (7) and to the lever (4) via a second connection point (8), thereby enabling energy transfer between the linear drive (2) and the lever (4) exclusively through the coupling element (6), the coupling element (6) being rotatably connected at both connection points (7, 8), and the maximum force provided by the linear drive (2) being limited according to the current gear ratio of the gear unit (3).

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

3. The method according to claim 1 or 2, characterized in that, at the initial position (100) of the gear device (3), a first stop (30), preferably fixed to the housing, is provided to fix the initial position (100), and / or, at the final position (80) of the gear device (3), a second stop (31), preferably fixed to the housing, is provided to fix the final position (80), and the first lever end (9) is configured to bring the lever (4) into contact with the first and / or second stop (30, 31).

4. The method according to claim 1 or 2, characterized in that, at the final position (80) of the gear device (3), a second stop part (31), preferably fixed to the housing, is provided to fix the final position (80), and the spindle end or end cap (51) of the spindle (50) of the linear drive (2) is configured to stop the spindle (50) relative to the second stop part (31).

5. The method according to any one of claims 1 to 4, characterized in that the value of the gear ratio at a moving position along the moving axis (41) of the linear drive (2) is calculated from the ratio Δφ of the rotation angle to be determined, which is obtained from the rotational movement of the shaft (5) obtained from the movement of the linear drive (2) and a predetermined distance Δx over which the linear drive (2) moves along the moving axis (41) of the linear drive (2) starting from the moving position.

6. The method according to any one of claims 1 to 5, characterized in that the process of determining the gear ratio value is stored according to the moving position of the linear drive (2).

7. The method according to any one of claims 1 to 6, characterized in that the dependence of the gear ratio value on the moving position of the linear drive (2) is not linear.

8. The method according to any one of claims 1 to 7, characterized in that the final position (80) has a predetermined final position threshold with respect to the gear ratio.

9. The method according to any one of claims 1 to 8, characterized in that when the direction of movement of the linear drive (2) is toward the final position (80) and the gear ratio at the current position exceeds the final position threshold, the force of the linear drive (2) is limited along the movement axis (41) of the linear drive (2).

10. The method according to claim 8, characterized in that the restriction stops the linear drive (2).

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