Actuator for providing a torque, said actuator comprising a linear drive

Abstract

The invention relates to an actuator (1) for providing a torque, said actuator comprising a linear drive (2) and a gearbox (3) for converting a linear movement into a rotational movement, the gearbox (3) comprising a lever (4) which rotationally drives a shaft (5) to which the torque is to be applied, the gearbox (3) also having 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) with 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) being rotatably mounted at both connection points (7, 8).

Description

[0001] Actuator for providing torque with a linear drive

[0002] The present invention relates to an actuator for providing a torque with a linear drive and a gear for converting a linear movement into a rotary movement, wherein the gear comprises a lever which drives a shaft to be subjected to the torque.

[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] An actuator, preferably for a clutch actuation with an articulated transmission between a linear gear and a shaft is known from WO 2015 070 850 A1.

[0005] In general, such an actuator is already known from DE 10 2018 116 133 A1.

[0006] The present invention has the object of providing a generic actuator with a non-linear characteristic curve in a simple manner.

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

[0008] According to the invention, the gear of the actuator further comprises a coupling element which 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 the coupling element is rotatably mounted in both connection points.

[0009] In addition to the lever and the linear drive, the coupling element provides a third component connecting them, which can be mounted in a particularly simple manner and enables a non-linear characteristic curve of the actuator through a corresponding energy transfer from the linear drive to the lever and thus to the shaft.

[0010] It is further provided that the lever is connected to the shaft at a second lever end via a third connection point in a rotationally fixed manner and to the coupling element at a first 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 easily adjusted, since it is not the distance between the second lever end and the shaft that can be varied, but only the transmitted torque or the corresponding rotational speed. In other words, the movement of the lever in space is defined by the position of the third connection point fixed to the housing 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.

[0011] According to the invention, it is further 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, the second pivoting movement causes a rotation of the shaft. The path covered by the second connection point is predetermined by the constraint of the rigid lever. The corresponding superposition of the two pivoting movements to form a fixed, predetermined curve accordingly determines the non-linearity of the rotational speed or the transmitted torque.

[0012] The invention also provides 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 an intermediate transition range 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.

[0013] In a first alternative according to the invention, the coupling element is aligned perpendicular to the lever and the movement axis of the linear drive at the second end point, and the lever is aligned parallel to the movement axis. Force transmission is difficult with such an arrangement. The force acting from the linear drive on the coupling element acts perpendicularly 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.

[0014] In a second arrangement according to the invention, it is alternatively or additionally provided that the coupling element is aligned parallel to the movement axis of the linear drive and perpendicular to the lever at the first end point. This results in maximum torque and minimum rotational speed. Accordingly, a stable position of the actuator is also achieved here.

[0015] In a further development of the invention, it can be provided that a first stop, preferably fixed to the housing, is provided in the first end point for fixing the first end point and / or a second stop, preferably fixed to the housing, 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.

[0016] In particular, it can be provided that the first and / or second stop is formed integrally from an actuator housing.

[0017] 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.

[0018] 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 reaching the particular stop, 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.

[0019] In order to enable the stops to be approached in a particularly controlled manner for adjusting or calibrating the actuator, a further development provides for the first and / or second stop to have a specific softness so that a predetermined linear movement of the linear drive is possible.

[0020] 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.

[0021] 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.

[0022] Finally, the invention relates to an actuator comprising a linear drive and gear for converting a linear movement into a rotary movement. 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, while the connection point of the coupling element on the lever is pivoted exclusively along a circular path with a specified radius r around the shaft axis, while the distance between the two connection points on the lever and the linear drive always remains constant. 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 operating range and a lower angular velocity at a higher torque in a second operating range to drive the shaft. A corresponding transition zone is located between the two operating ranges.

[0023] In this way, the shaft can produce a rotational movement with a variable

[0024] A characteristic curve can be provided, 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 a drive train of a motor vehicle or commercial vehicle.

[0025] The toggle lever mechanism described here creates a nonlinear characteristic curve between the linear propulsion of the linear drive, e.g., a spindle travel and the rotation of the lever, or the drive force of the linear drive, 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. One example of this is the actuation of a parking lock.

[0026] 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.

[0027] An embodiment of the invention, to which it is not limited, and from which further inventive features may arise, is shown in the following figures. They show:

[0028] Fig. 1 shows an actuator according to the invention with a partial sectional view,

[0029] Fig. 2: a symbolic representation of a trajectory curve of the lever for shaft actuation,

[0030] Fig. 3: an alternative arrangement of a coupling element between a lever and a spindle

[0031] Fig. 4 is an illustration of the torques generated by the actuator according to Fig. 3,

[0032] Fig. 5 and 6: an actuator according to Fig. 1 in sectional view with a lever in a first end point and a second end point Fig. 7: one half of an actuator housing

[0033] 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.

[0034] 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.

[0035] The support roller 52 represents a first connection point 7 for the rotatable mounting of the coupling element 6.

[0036] 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.

[0037] 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 connected to a shaft 5 in a rotationally fixed manner 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.

[0038] 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 similar, 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. The 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.

[0039] 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.

[0040] 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.

[0041] In the right-hand 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. In the area between the two end points 21, 22, the lever 4 is thus driven with a non-linear torque characteristic. The shaft 5 is driven accordingly, and the non-linear characteristic of the shaft 5 can be used to actuate a non-linear load, such as a parking lock.

[0042] 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' symbolizes the transmitted torque.

[0043] The trajectories 20 and 20' of the two alternatives in Figs. 2 and 4 are practically mirrored and otherwise identical. However, the rotation directions at minimum and maximum torque of shaft 5 are reversed, i.e., the rotational movements 23, 23' and 24, 24' are each 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.

[0044] 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' then also enables actuation according to the alternative in Fig. 4.

[0045] However, the same applies to the generation of the non-linear characteristic curve of shaft 5 as already described in Fig. 1.

[0046] 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.

[0047] 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. In Fig. 6, a maximum torque is generated on the shaft 5 when the spindle 50 is retracted toward the linear drive 2.

[0048] 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.

[0049] 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.

[0050] Figs. 5 and 6 further show that the spindle 50 is driven by a nut 71. This 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.

[0051] 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.

[0052] In Fig. 7, one half of an actuator housing 40 is shown.

[0053] 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.

[0054] Using the actuator 1 shown here, based on the toggle lever principle, a non-linear actuation characteristic can be easily implemented on an actuating element 60 via a linear drive 2. The provided stops 30, 31 prevent accidental adjustment due to vibrations or similar, and also ensure a defined position of the actuator 1, e.g., in the event of a power failure. Reliable actuation with good efficiency can be achieved via the support surfaces 44 in conjunction with the support rollers 52.

[0055] List of reference symbols

[0056] Actuator

[0057] Linear drive

[0058] Gearbox

[0059] lever

[0060] 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 first swivel movement 6 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 5 External toothing 6 Shaft axis 7 Direction of extension 0 Actuating element 1 Direction

[0061] 70 spindle drive

[0062] 71 mother

[0063] 72 Gearing point

[0064] 73 rotor bearings

[0065] 74 Rotor

[0066] 75 electric motor

[0067] P1 , P2 spindle positions

Claims

Patent claims 1. Actuator (1) for providing a torque with a linear drive (2) and a gear (3) for converting a linear movement into a rotary movement, wherein the gear (3) comprises a lever (4) which rotatably drives a shaft (5) to be subjected to the torque, wherein the gear (3) further comprises 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 mounted in both connection points (7, 8),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 lever (4) establishes a rigid connection between the two connection points (8, 10), the coupling element (6) establishes a rigid connection between the first and second connection points (7, 8), so that a linear movement of the first connection point (7) by the linear drive (2) results in a first pivoting movement (25) of the second connection point (8) about the first connection point (7) and in a second pivoting movement (26) of the second connection point (8) about the third connection point (10), so that due to the rotationally fixed connection of the lever (4) to the shaft (5), a rotation of the shaft (5) is caused by the second pivoting movement (26),and the coupling element (6) connects the lever (4) and the linear drive (2) to one another in such a way that the second connection point (8) is moved along a trajectory curve (20, 20'), so that in a first working range around a first end point (21, 21') of the trajectory curve (20, 20') a movement of the first connection point (7) is translated by the linear drive (2) into a first rotational movement (23, 23') of the shaft (5) and in a second working range around a second end point (22, 22') a movement of the first connection point, (7) is reduced by the linear drive (2) into a second rotational movement (24, 24') of the shaft (5), wherein the first rotational movement (23, 23') covers a larger angular range with a smaller force transmission in a time interval than the second rotational movement (24, 24'), characterized in that in the second end point (22, 22') the coupling element (6) is aligned perpendicular to the lever (4) and to the movement axis (41) of the linear drive (2) and the lever (4) is aligned parallel to the movement axis (41) and / or in the first end point (21, 21') the coupling element (6) is aligned parallel to the movement axis (41) of the linear drive (2) and perpendicular to the lever (4).

2. Actuator (1) according to claim 1, characterized in that in the first end point (21, 21') a first, preferably housing-fixed stop (30) for fixing the first end point (21, 21') and / or in the second end point (22, 22') a second, preferably housing-fixed stop for fixing the second end point (22, 22') is provided, and wherein the first lever end (9) is designed to stop the lever (4) against the first and / or second stop (30).

3. Actuator (1) according to claim 1 or 2, characterized in that a second, preferably housing-fixed stop (31) is provided for fixing the second end point (22, 22'), wherein the spindle (50) or the end cap (51) of the spindle (50) is designed to abut against the second stop (31).

4. Actuator (1) according to claim 2 or 3, characterized in that the first and / or second stop (30, 31) is formed integrally from an actuator housing (40).

5. Actuator (1) according to one of claims 2 to 4, characterized in that the first and / or second stop (30, 31) have a targeted softness, so that a predetermined linear movement of the linear drive (2) is made possible.

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