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EP-4739932-A1 - METHOD FOR FOR THE SAFE OPERATION OF AN ACTUATOR

EP4739932A1EP 4739932 A1EP4739932 A1EP 4739932A1EP-4739932-A1

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).

Inventors

  • GREB, PETER
  • MAN, LASZLO

Assignees

  • Schaeffler Technologies AG & Co. KG

Dates

Publication Date
20260513
Application Date
20240603

Claims (10)

  1. 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 transmission (3).
  2. 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) rotatably 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. 3. Method according to claim 1 or 2, characterized in that in an initial position (100) of the transmission (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 transmission (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 to stop the lever (4) against the first and/or second stop (30, 31).
  4. 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. 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 that the linear drive (2) moves along the movement axis (41) of the linear drive (2), starting from the travel position.
  6. 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. 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. 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. 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. 10. Method according to claim 8, characterized in that the limitation stops the linear drive (2).

Description

Method for the safe operation of an actuator The present invention relates to a method for the safe operation of an actuator with the features according to the preamble of claim 1. Such actuators are already known from DE 10 2016 207 827 A1 with a non-linear actuation force for an actuation unit for an automatic transmission (preferably a PRND automatic transmission system) of a motor vehicle. For this purpose, a corresponding slide track is provided to generate the non-linearity. In general, such an actuator is already known from DE 10 2018 116 133 A1. The applicant's as yet unpublished German patent application with the reference number 10 2023 115 292.0 also discloses an actuator with a non-linear characteristic curve. The toggle lever kinematics used in this actuator concept result in an actuating force (torque) on the output shaft (5) that in principle tends towards infinity when the drive torque of the electric motor is constant in an end position (Fig. 1, Fig. 8) of the toggle lever mechanism, which can lead to damage to the load to be actuated or to parts of the actuator itself. The present invention has the task of operating such an actuator safely in a simple manner. This object of the invention is achieved by a method having the features of claim 1. 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 drives the shaft to be subjected to the torque in rotation, 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 the coupling element is rotatably connected at both connection points. It is provided that the maximum force provided by the linear drive is limited depending on a current value of a gear ratio of the transmission. The current value of the gear ratio of the gearbox is available depending on the travel position along the movement axis of the linear drive, for example a spindle of a spindle drive, and is, for example, already learned end-of-line or newly determined in a referencing or update process. The current gear ratio is therefore the value for the gear ratio at the current travel position. 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 is rotatably connected to the coupling element via the second connection point and the coupling element is rotatably connected to the linear drive via the first connection point and the lever establishes a rigid connection between the two connection points. In a further preferred embodiment of the invention, it is provided that in an initial position of the transmission a first, preferably housing-fixed stop is provided for fixing the initial position and/or in an end position of the transmission a second, preferably housing-fixed stop is provided for fixing the end position, and wherein the first lever end is designed to stop the lever against the first and/or second stop. In an alternative preferred embodiment of the invention, it is provided that in an end position of the gear a second, preferably housing-fixed stop is provided for fixing 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 predetermined distance Ax that the linear drive moves along the movement axis of the linear drive, starting from the travel position. 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 travel of the spindle. A specified spindle drive, for example designated as Ax, leads to a rotation of the shaft that is to be determined, for example designated as Acp. The transmission ratio is the quotient Acp / Ax of both values. Due to the non-linearity of the transmission of the toggle lever kinematics, the transmission is not the same all the way between the initial position and the final position, but takes on different values at each position between the initial position and the final position. For each travel po