Method for controlling an actuating assembly for a clutch, and a drive assembly having an actuating assembly

Description

[0001] The invention relates to an actuating arrangement for operating a clutch in the drivetrain of a motor vehicle, in particular a motor vehicle with an electric drive. An electric drive can serve as the sole drive for the motor vehicle, or an internal combustion engine can also be provided. In this case, the electric drive and the internal combustion engine can each drive the motor vehicle independently or together in a superimposed manner. Such drive concepts are also referred to as "hybrid drives".

[0002] An electric drive system typically comprises an electric motor and a downstream reduction gearbox that converts a rotary motion from fast to slow. The reduction gearbox then transmits the torque to the vehicle's drivetrain. A differential gearbox, located downstream of the reduction gearbox in the torque flow, divides the applied torque between two output shafts to drive the vehicle's wheels. The two output shafts of the differential gearbox have a compensating effect on each other; that is, if one output shaft rotates faster, the other rotates correspondingly slower, and vice versa.

[0003] From DE 10 2007 008 977 A1, a method for controlling a clutch in the drive train of a vehicle is known, in which the clutch torque is controlled in a first range depending on the position of the actuating element and in a second range depending on the force applied to the clutch by the actuating element. The control unit contains two characteristic curves, one for control depending on position and one for control depending on force, as well as a switching device that switches the control of the actuator from one characteristic curve to the other.

[0004] From WO 2012 / 087700 A1, an electric drive module is known comprising an electric motor, a planetary gear unit, a synchronizing unit, a reduction gear unit, and a differential arrangement. The synchronizing unit is actuated by means of an actuator comprising a rotatably driven spindle drive for axially moving a shift fork that interacts with a sliding sleeve of the synchronizing unit.

[0005] From WO 2007 / 110131 A1, an actuation arrangement for a shift clutch of a multi-stage transmission is known. The actuation arrangement comprises an electric machine, a rotating shaft driven by the machine, and an actuating element arranged on the rotating shaft. The actuating element is coupled to a rotor of the electric machine via a rotary-translation converter.

[0006] From DE 10 2006 011 207 A1, a sensor arrangement for detecting the position of a movable element is known. The sensor arrangement comprises a magnetic field sensor that detects different magnetic field strengths in different positions of the movable element.

[0007] From WO 2005 / 098269 A2, an automated transmission with several gear stages is known, which can be engaged and disengaged by means of respective shift clutches. The shift clutches are designed in the form of synchronous clutches, which are actuated by means of an axially displaceable shift sleeve. The shift sleeve is actuated by means of a controllable actuator.

[0008] From DE 10 2005 022 926 B3, a method for optimizing the shifting sequence of a stepped transmission of a motor vehicle is known. The stepped transmission has several gear stages that can be engaged and disengaged by means of respective shift clutches.

[0009] The switching sequence involves detecting a tolerance- and / or wear-dependent parameter and setting a target position of a switching element of the clutch corresponding to the parameter.

[0010] Electric drives with multi-speed transmissions and clutch shifting require considerable structural complexity for the clutches and actuators. Multi-speed transmissions with synchronizers demand high shifting forces, which places high demands on the actuator. Furthermore, manufacturing tolerances and wear occurring over the service life can lead to shifting inaccuracies.

[0011] The present invention is based on the objective of proposing a method for controlling an actuation arrangement for a clutch, enabling comfortable or rapid shifting and compensation for positional changes caused by varying tolerances of the individual parts and wear during the service life. Furthermore, the object is to propose an actuation arrangement for carrying out the method, as well as a drive arrangement incorporating such an actuation arrangement.

[0012] One solution consists of a method for controlling an actuating arrangement for a clutch unit in the drive train of a motor vehicle, wherein the actuating arrangement comprises an actuator drive for moving an actuating element for actuating the clutch, and wherein the method comprises the following steps: sensing a position signal representing the position of the actuating element; sensing a force signal representing the actuating force for moving the actuating element; linking a sensed position signal and an associated sensed force signal to determine an exact position of the actuating element; and controlling the actuator drive by means of an electronic control unit depending on the position signal and the force signal associated therewith.

[0013] By considering both a position signal and a force signal to control the actuator drive, the actuation arrangement can be calibrated during operation. This allows for the compensation of positional changes in the components involved in actuating the clutch that occur over the system's service life. Furthermore, manufacturing tolerances and elasticities of the components involved can be advantageously compensated for. Overall, this method offers the advantage of particularly robust and reliable control throughout the entire service life of the clutch or the actuation arrangement.

[0014] The position signal can, in one possibility, be a displacement signal, meaning that to determine the position of the actuator, a displacement signal representing the actuator's path is sensed, for example, using a non-contact displacement sensor. Alternatively or additionally, the position signal can be a rotation signal, meaning that to determine the position of the actuator, a rotation signal representing the actuator's rotational movement is sensed, from which the actuator's position is determined.

[0015] Preferably, during a first clutch operation, an end position of the actuating element, representing an end stop of the clutch unit in the closed position, is sensed by a sudden increase in the force signal, and a corresponding end position value is stored. Furthermore, it is provided that in at least one subsequent clutch operation, occurring after the first, the end position value is taken into account by the electronic control unit when activating the actuator drive, such that the actuating element is decelerated before reaching the end position. By decelerating the actuating element or an associated coupling element before reaching the end position, unwanted impact noises from the clutch unit can be avoided, and shifting comfort can be improved. Preferably, the end position value is defined based on a position signal sensed at the time of the sudden increase in the force signal.This means that a force signal and an associated position signal are linked together, so that the exact position of the actuating element or the associated coupling element can be determined.

[0016] After reaching the end position, the actuating element is moved back a defined distance to a coupling position axially spaced from the end position, according to a preferred procedure. This avoids frictional forces in the engaged state, as axial play is established in the actuating arrangement or clutch unit by the slight retraction of the actuating element. The axial distance between the end position and the coupling position, or the distance by which the actuating element is retracted, is preferably between zero and 1.0 mm. This distance can be adjusted depending on the wear situation, which extends the functionality and service life of the transmission and, if applicable, a synchronizing mechanism.

[0017] In a subsequent coupling operation, the actuator drive can be controlled in such a way that the actuating element is moved directly into the coupling position, meaning it is stopped in the coupling position before reaching the end position. This prevents an unwanted impact noise, while still ensuring the coupling position is reliably reached due to the prior calibration at the end stop. A subsequent coupling operation refers to any coupling operation that occurs after a previous coupling operation in which the control system was calibrated by approaching the end stop. Whether the coupling position is approached directly or only after first approaching the end stop can be configured as needed and is based on algorithms stored in the electronic control unit.For example, it can be defined that the clutch position is approached directly when a rapid clutch engagement is desired, such as when shifting from one gear to the next during acceleration. An indirect approach to the clutch position, after first reaching the end stop, can occur during clutch engagement under normal load. The clutch position can also be referred to as the gear position. Only by knowing the specific positions of the transmission can a gear position be approached directly without compromising shift robustness. The risk of the distance to the end stop being too great and the gear unexpectedly popping out is significantly reduced.

[0018] The clutch unit can include a synchronizing mechanism which, in a synchronizing position of the actuating element, synchronizes the first rotational speed of a clutch input part and the second rotational speed of a clutch output part. In an embodiment with a synchronizing mechanism, the actuator drive can be controlled during the clutch engagement process such that the feed rate of the actuating element is reduced before reaching the synchronizing position. Here, too, the control can be adjusted to suit the vehicle's driving characteristics. If a smooth clutch engagement or shifting process is desired, the feed rate can be reduced before reaching the synchronizing position to avoid unwanted shifting noises.After the synchronization phase, that is, when the relative speed difference between the clutch input and output sections has fallen below a predetermined differential speed value, the feed rate of the actuating element can then be increased again to move it into the clutch position. However, if rapid clutch engagement or shifting is the priority, the actuating element can also be moved at a constant feed rate until the clutch position is reached.

[0019] According to a possible procedure, the actuating element is returned to the neutral position if the relative speed difference between the clutch input part and the clutch output part is still greater than the predetermined differential speed value after a specified time period. This predetermined time period until the clutch process is terminated can be, in particular, between 0.3 and 0.7 seconds.

[0020] The actuator drive for the actuating element is, in one possible embodiment, designed as an electric motor, although other drives such as hydraulic or pneumatic rotary drives, as well as linear drives, are also conceivable. For electrically operated drives, the process step of sensing the force signal preferably comprises the following sub-steps: sensing the current of the actuator drive and calculating the force of the actuating element from the determined current or current requirement of the actuator drive. This design advantageously utilizes a signal that is already available, namely a signal representing the current requirement of the actuator drive.

[0021] The solution to the aforementioned problem further comprises a drive arrangement according to claim 9 with a clutch unit for the drivetrain of a motor vehicle, in particular for an electrically driven drivetrain of a motor vehicle, and with an actuating arrangement for actuating the clutch unit. The clutch unit can be selectively moved by means of the actuating arrangement into a clutch position in which torque is transmitted between a clutch input part and a clutch output part, and into a neutral position in which the clutch input part and the clutch output part are freely rotatable relative to each other, wherein the clutch unit includes a synchronizing mechanism which, before closing into the clutch position, causes an equalization of speeds between the clutch input part and the clutch output part.The actuation arrangement comprises an actuator drive with a rotatable shaft; a rotation-translation converter that converts a rotational movement of the shaft into a translational movement of an actuating element; first sensor means that sens a position signal representing the translational movement of the actuating element; second sensor means that sens a force signal representing the force of the actuator drive; and an electronic control unit for controlling the actuator drive, wherein the electronic control unit is connected to the first sensor means and to the second sensor means in order to combine a sensed position signal and a sensed force signal for the precise determination of the position of the actuating element and to use them for controlling the actuator drive.

[0022] The drive arrangement achieves the same advantages as the aforementioned method, the description of which is referenced here. It is understood that all embodiments mentioned in connection with the method are also transferable to or applicable to the device (drive arrangement), and conversely, all device features also apply to the method. Due to the two sensor means used, the drive arrangement according to the invention enables calibration, so that all changes occurring over its service life in the control of the actuation arrangement can be taken into account. The actuation arrangement thus operates particularly robustly and reliably, meaning that the risk of malfunctions is minimized.

[0023] The first sensor means, according to one possibility, comprise a displacement sensor, particularly one that operates without contact, which at least indirectly detects a movement of the actuating element as a position signal. For this purpose, the first sensor means can, for example, include a magnetic field sensor arranged in a housing of the actuating arrangement and capable of detecting the movement of a signal transmitter connected to the actuating element. The axial position of the signal transmitter can be continuously sensed by the sensor. The signal transmitter, for example a magnet, can be directly connected to the actuating element or indirectly via a component connected to the actuating element.According to a supplementary or alternative second possibility, the first sensor means can have a rotary angle sensor which at least indirectly senses a rotary movement of the actuator drive as a position signal, whereby the position of the actuating element is determined from the sensed rotary movement of the actuator drive.

[0024] The second sensor means preferably include a current sensor that detects the current draw of the actuator drive. The axial force acting on the actuating element can then be calculated from this current draw in a processing unit.

[0025] The rotary-translational converter preferably comprises a threaded spindle with a spindle section that can be driven by the shaft in a rotating manner, and a sliding section screwed to the spindle section. The sliding section is guided in a rotationally fixed and longitudinally displaceable manner relative to a housing, such that rotation of the spindle section causes axial displacement of the sliding section. Preferably, the sliding section is designed in a sleeve- or tube-shaped form and has an internal thread at one end section that is screwed onto a corresponding external thread of the spindle section. The tubular sliding section can be mounted longitudinally displaceable at both end sections within the housing. The actuating element, which can be designed, for example, in the form of a switching fork, is fixed to the sliding section so that it moves axially together with it. In a favorable embodiment, the signal transmitter for the position sensor is connected to the sliding section.

[0026] The drive arrangement can have one or more of the configurations mentioned above. The coupling unit can have one or more couplings. The coupling unit can be selectively moved by means of the actuating arrangement either into a coupling position in which torque is transmitted between a coupling input part and a coupling output part, or into a neutral position in which the coupling input part and the coupling output part are freely rotatable relative to each other.

[0027] The drive system can be, in particular, part of an electric drive, which has an electric motor to power the vehicle's drivetrain. Alternatively, the drive system can be part of an all-wheel-drive deactivation system, i.e., a deactivation system for an all-wheel-drive vehicle. Both configurations, electric drive or all-wheel-drive deactivation system, exhibit relatively high inertia, which is why sensitive control of the actuation based on position and force signals is particularly well-suited for comparison with other systems.

[0028] The clutch unit includes a synchronizing mechanism that synchronizes the speeds between the clutch input part and the clutch output part before the respective clutch is closed.

[0029] Preferably, the clutch input part is connected to a drive shaft in a rotationally fixed manner, and the clutch output part is connected to a drive wheel rotatably mounted on the drive shaft in a rotationally fixed manner.

[0030] In one possible embodiment, a second clutch can be provided which can be selectively moved into either a closed or an open position by means of the actuating arrangement. The second clutch output part is preferably rotationally fixed to a second drive wheel rotatably mounted on the drive shaft. In this case, the first and second clutches can be parts of a transmission which, by engaging the first clutch, can transmit torque from the drive shaft to the output shaft via a first gear stage with a first gear ratio, or, by engaging the second clutch, can transmit torque with a second gear ratio.

[0031] Preferably, a coupling element is provided which is rigidly connected to the actuating element of the actuating arrangement, wherein the coupling element can be moved into the following positions: a neutral position in which the coupling input part, the first coupling output part, and the second coupling output part are freely rotatable relative to each other; a first coupling position in which the coupling input part is connected to the first coupling output part for transmitting a torque; or into a second coupling position in which the coupling input part is connected to the second coupling output part for transmitting a torque. According to a preferred embodiment, the coupling element is designed in the form of a sliding sleeve which is held rotationally fixed and axially displaceable relative to the coupling input part. By actuating the actuating arrangement, the sliding sleeve can be selectively moved into the aforementioned positions.

[0032] Preferred embodiments are explained below with reference to the drawing figures. These show: Figure 1 shows a drive arrangement according to the invention with an actuator arrangement according to the invention in a sectional view; Figure 2 shows the actuation arrangement made of Figure 1 in detail; Figure 3 the drive shaft 9 from Figure 1 or Figure 2 with components mounted on it as a detail; Figure 4 schematically shows a drive arrangement according to the invention with an electric motor; Figure 5 shows the drive arrangement made of Figure 4 in neutral position (N); Figure 6 the drive arrangement from Figure 4 in a first switching position (C1); Figure 7 the drive arrangement from Figure 4 in a second switching position (C2); Figure 8 the arrangement of Figure 3 in neutral position (N) a) in longitudinal section; b) a part of the gearing in unfolded form; c) a characteristic curve diagram showing various parameters over time; Figure 9 the arrangement of Figure 3in synchronizing position (S) a) in longitudinal section; b) a part of the gearing in unfolded form; c) the characteristic curve diagram from Figure 8c ); Figure 10 the arrangement of Figure 3 in synchronous position a) in longitudinal section; b) a part of the gear teeth in unfolded form; c) the characteristic curve diagram from Figure 8c ); Figure 11 the arrangement of Figure 3 in positive locking position a) in longitudinal section; b) a part of the gear teeth in unfolded form; c) the characteristic curve diagram from Figure 8c ); Figure 12 the arrangement of Figure 3 in coupling position (C1) a) in longitudinal section; b) a part of the gear teeth in unfolded form; c) the characteristic curve diagram from Figure 8c ).

[0033] The Figures 1 to 7 will be described together below. Figure 1Figure 1 shows an actuation arrangement 1 according to the invention as part of a drive arrangement 2 according to the invention. The drive arrangement 2 comprises an electric motor 3, a transmission 4, and a differential 5. The electric motor 3, transmission 4, and differential 5 together form an electric drive for powering a drive axle of a motor vehicle. The electric drive can be used as the sole power source or with an additional power source.

[0034] The electric motor 3 comprises a stator 6 and a rotatable rotor 7, which, when the electric motor is energized, drives a motor shaft 8. The rotational movement of the motor shaft 8 is transmitted to the drive shaft 9 of the gearbox 4. The electric motor 3 is supplied with electrical current by a battery, which can also be charged by the electric motor when operating as a generator.

[0035] The transmission 4 comprises two gear stages, allowing the applied torque from the drive shaft 9 to be transmitted to the intermediate shaft 10 with two different gear ratios i1 and i2. The intermediate shaft 10 is connected to the differential carrier 11 of the differential 5. The differential 5 distributes the applied torque to two side shafts 81 and 82 to drive the vehicle wheels. A clutch unit 12 is provided, which can be actuated by an actuator 13 to select neutral, first gear, or second gear for the transmission 4. The design and operation of the clutch unit 12, which can also be referred to as the shift unit, will be discussed in more detail below.

[0036] The transmission 4 is designed as a reduction gear, such that a rotary motion initiated by the electric motor 3 is reduced from high to low speed. The first gear stage comprises a first drive gear 14 rotatably mounted on the drive shaft 9 and a first intermediate gear 15 non-rotatably connected to the intermediate shaft 10, which mesh with each other. The first drive gear 14 and the first intermediate gear 15 form a first gear set with a first gear ratio i1, preferably between 3.0 and 4.0. The second gear stage comprises a second drive gear 16 rotatably mounted on the drive shaft 9 and a second intermediate gear 17 non-rotatably connected to the intermediate shaft 10, which mesh with each other. The second drive gear 16 and the second intermediate gear 17 form a second gear set with a second gear ratio i2, preferably between 1.3 and 2.3.A third transmission stage comprises the output gear 18, which is rotationally fixed to the intermediate shaft 10, and the ring gear 19, which meshes with it and is fixedly connected to the differential carrier 11. The output gear 18 of the intermediate shaft 11 and the ring gear 19 form a third gear set with a third transmission ratio i3, which is preferably between 2.4 and 3.4.

[0037] The drive shaft 9 is rotatably mounted about a first axis of rotation A9 in a housing 26 of the drive assembly 2 by means of first bearing means 24, 25. The annular space formed on the input side of the drive shaft 9 between the shaft and the housing 26 is sealed by means of a radial shaft seal 27. The drive gears 14, 16 are rotatably mounted on the drive shaft 9 by means of respective bearing means 20, 21. The intermediate shaft 10 is rotatably mounted about a second axis of rotation A10 in the housing 26 by means of second bearing means 32, 33. The bearing means 32, 33 are designed as rolling bearings, which are provided at the ends of the intermediate shaft 10. The output gear 18 is integrally mounted with the intermediate shaft 10 and axially arranged between the first and second intermediate gears 15, 17. The intermediate gears 15, 17 are connected to the intermediate shaft 10 in a rotationally fixed manner via shaft teeth 22, 23 (splines), in particular with an interference fit.The drive shaft 9, the intermediate shaft 10, and the axis of rotation A11 of the differential carrier 11 are parallel to each other. The driven gear 18 of the intermediate shaft 10 has at least partial axial overlap with the differential center plane E5. The housing 26 has a first housing part 28 and a second housing part 29, which are connected to each other in a joining plane E26 by means of suitable connecting elements 30, such as screw connections. Furthermore, the joining plane E26 of the housing 26 is in axial overlap with the intermediate shaft output gear 18, or the clutch unit 12.

[0038] The output gear 18 of the intermediate shaft 10 meshes with the ring gear 19 of the differential carrier 11 to transmit torque to the differential. The differential carrier 11, also referred to as the differential cage, is rotatably mounted in the housing 26 about the axis of rotation A11 by means of bearings 34, 35 and sealed by radial shaft seals 36, 37. The differential 5 further comprises several differential gears 38, which are rotatably mounted in the differential carrier 11 on an axis A38 perpendicular to the axis of rotation A11, as well as two side shaft gears 39, 40, which are each rotatably arranged coaxially with the axis of rotation A11 and mesh with the differential gears 38. Two opposing differential gears 38 are rotatably mounted on a journal 41, which is inserted into bores in the differential carrier 11 and axially fixed. The axis A38 of the differential gears 38 defines a differential center plane E5.The torque introduced from the ring gear 19 into the differential carrier 11 is transmitted via the differential gears 38 to the two side shaft gears 39, 40, between which a balancing effect exists. The side shaft gears 39, 40 are connected to the associated side shafts 81, 82 for the transmission of torque, which in turn transmits the introduced torque to the wheels 83, 84 of the motor vehicle, as shown in [reference]. Figures 4 to 7 shown. The two side shaft gears 39, 40 each have internal teeth into which a corresponding side shaft with a corresponding external tooth can engage in a rotationally fixed manner to transmit a torque.

[0039] The coupling unit 12, which is described in detail in the Figures 2 and 3The coupling unit, as shown, is arranged axially between the first drive wheel 14 and the second drive wheel 16. It comprises an input part 42, which is rotationally fixed and axially fixed to the drive shaft 9; a first output part 43, which is rigidly connected to the first drive wheel 14; and a second output part 44, which is rigidly connected to the second drive wheel 16. A coupling element 45 is provided, which can optionally connect the input part 42 to either the first output part 43 or the second output part 44 to transmit torque. The coupling element 45 is designed as a sliding sleeve, which is held on the input part 44 in a rotationally fixed and axially displaceable manner.

[0040] The actuation of the sliding sleeve 45 is effected via the actuation arrangement 1 according to the invention. The actuation arrangement 1 comprises a drive 46 in the form of an electric motor and a rotary-translation converter 47, which converts a rotary motion into a linear motion. The converter unit 47 is designed, in particular, in the form of a threaded spindle and includes a rotatably driven spindle part 48 and a sliding part 49 screwed to it, which is moved axially when the spindle part rotates. An actuating element 50 in the form of a switching fork is attached to the sliding part 49, which is designed in the form of a corrugated tube. The switching fork 50 engages with two sliding blocks 52 in an annular groove 53 of the sliding sleeve 45. The actuation arrangement 1 can be controlled by an electronic control unit (ECU) and is actuated by it as required, depending on the current or desired driving states of the vehicle.

[0041] For precise control and positioning of the switching sleeve 45, first sensor means 54 are provided, which can detect a signal representing the axial position of the switching fork 50 or the switching sleeve 45 and transmit it to the control unit. The first sensor means 54 are designed as non-contact displacement sensors, in particular as magnetic field sensors or inductive sensors. The use of a non-contact sensor has the advantage of low power losses and low wear. The non-contact sensor interacts with a signal transmitter 55. The sensor 54 detects the axial position of the signal transmitter 55 and transmits a corresponding sensor signal to the electronic control unit. The signal transmitter 55 is connected to the spindle sleeve 49, so that it is moved axially together with the actuator 13 when the actuator is actuated.The signal transmitter 55 is mounted in a support element which is fastened to the spindle sleeve by means of a screw connection 56. As an alternative to the displacement sensor, a rotary angle sensor can also be used to determine the position of the switching fork, which senses the rotary movement of the actuator drive 46, from which the position of the switching fork is then calculated.

[0042] In addition, data acquired by secondary sensors are used to control the actuating arrangement 1. These secondary sensors, in particular, detect a quantity representing the force required to axially move the sliding sleeve 45 or the spindle sleeve 49. For example, a current signal can be acquired to control the actuator, which is representative of the force required to drive the spindle part 48. These secondary sensors can also be referred to as force sensors.

[0043] The clutch unit 12 further comprises a synchronizing mechanism 57, 57' for each output part 43, 44, which synchronizes the speeds of the components to be connected before shifting, i.e., between the input part 42 and the respective output part 43, 44. Since the synchronizing mechanisms 57, 57' are identical in construction, only one is described as representative. The synchronizing mechanism 57 has an outer ring 58 with an inner cone, an inner ring 59 with an outer cone, and an intermediate ring 60 arranged between them. The outer ring 58 is rotationally fixed to the input part 42 such that both rotate together about the axis of rotation A9, whereby a limited relative rotation between the input part 42 and the outer ring 58 is possible. The intermediate ring 60 is rotationally fixed to the output part 43. The inner ring 59 is again rotationally fixed to the input part 42.This design ensures that the sliding sleeve 45 and the respective output parts 43, 44 can only engage when both are rotating at the same speed, i.e., when they are synchronized. Synchronization is achieved by means of several circumferentially distributed pressure pieces 62, which are rotationally fixed to the input part 42 such that they rotate with it. By axially moving the sliding sleeve 45, the pressure pieces 62 are pressed against the outer ring 58, creating frictional engagement at the surface pairings between the outer ring 58 and the intermediate ring 60 on the one hand, and between the intermediate ring 60 and the inner ring 59 on the other. This frictional engagement results in an equalization of the rotational speeds between the input part 42 and the respective output parts 43, 44.If the parts to be joined rotate synchronously, the sliding sleeve 45 can be fully moved into the engagement position, so that the input part 42 and the respective output part 43, 44 are connected to each other for the transmission of a torque. The pressure pieces 62 are each connected to the sliding sleeve 45 via a ball 63, which is preloaded radially outward by a spring 64. The ball 63 engages positively in an inner groove 65 of the sliding sleeve 45. If the axial actuating force of the sliding sleeve 45 exceeds the holding force of the ball 63, the ball is moved radially inward against the preload force of the spring 64, so that the sliding sleeve can be moved further toward the respective output part 43, 44.

[0044] The first output part 43 is rigidly connected to a first ring 66, in particular by welding. For this purpose, the first ring 66 has an annular recess in which the output part 43 sits. Radially on its inner side, the first ring 66 has a hub section that rests on a sleeve extension 67 of the first drive gear 14 and is welded to it (69). The first output part 43, the first ring 66, and the first drive gear 14 together form a first gear, which is rotatably mounted on the drive shaft 9 by means of the bearing means 19. The bearing means 20, 21 are designed as plain bearings and comprise two bearing bushings, although other suitable bearing means would also be conceivable. In the axial direction, the first gear is fixed between a first disk 72 and a second disk 73. The first disk 72 sits on a seat surface of the drive shaft 9 with an interference fit and is axially supported against a shoulder of the drive shaft.The second disc 73 is supported by a retaining ring 74 in the opposite axial direction to the drive shaft 9. The second output part 44, the second ring 66', and the second drive gear 16 accordingly form a second gear, which is designed analogously to the first gear. Therefore, reference is made to the description of the first gear with regard to all similarities, whereby corresponding details are identified by the same reference numerals and indices.

[0045] To ensure good lubrication and a long service life for the rotating components, the drive shaft 9 has a longitudinal bore 75 and, for each seating surface for the gears 42, 14, 16 arranged thereon, several transverse bores 76, 77, 77' distributed around its circumference. The input part 42 is press-fitted to the drive shaft 9 to prevent rotation. A retaining ring 78 is provided for axial retention, engaging in corresponding annular grooves in the drive shaft and the input part, respectively.

[0046] The following will refer with particular reference to the Figures 4 to 7 The circuit of the drive arrangement 2 according to the invention is explained. Figure 4 The figure schematically shows the drive arrangement 2 with electric motor 3 for driving the vehicle axle 80. The side shafts 81, 82 and the wheels 83, 84 connected thereto of the vehicle axle 80 are visible.

[0047] As explained above, the drive arrangement 2 has a two-speed transmission, which is formed by a first power path and a functionally parallel second power path. By appropriately controlling the clutch unit 12, torque can be selectively transmitted from the electric motor 3 to the differential 5 or the drive axle 80 via the first power path or alternatively via the second power path.

[0048] In Figure 5The clutch unit 12 is shown in neutral position (N), which can also be referred to as the idle position. The components connected to the electric motor 3 are shown in bold. It can be seen that the shift sleeve 45 is in a central position in neutral. In this position, the electric motor 3 and the differential 5 are decoupled from each other, so that no torque transmission can occur between the side shafts 81, 82 and the electric motor 3. This is necessary, for example, if the vehicle needs to be towed in the event of a breakdown.

[0049] In the first switching position (C1), which is in Figure 6As shown, the sliding sleeve 45 is rotationally fixed to the first output part 43, or first drive gear 14. Torque is transmitted from the electric motor 3 to the differential 5 via the first power path, which is shown in bold. The first power path comprises the drive shaft 9 driven by the electric motor 3, the input part 42, the first drive gear 14, the first intermediate gear 15, the intermediate shaft 10, and the output gear 18, which meshes with the ring gear 19 to drive the differential 5.

[0050] In the second switching position (C2), which is in Figure 7As shown, the sliding sleeve 45 is coupled to the second output part 44, or second drive gear 16, so that torque is transmitted via the second power path, which is again shown in bold. The second power path comprises the drive shaft 9, the input part 42, the second drive gear 16, the second intermediate gear 17, the intermediate shaft 10, and the output gear 18, which meshes with the ring gear 19.

[0051] The drive arrangement 2 has a total of three gear pairs: the first drive gear 14 and the first intermediate gear 15 (first gear pair), the second drive gear 16 and the second intermediate gear 17 (second gear pair), and the output gear 18 and the ring gear 19 (third gear pair). Depending on the switching position of the clutch unit 12, the drive is via the first or the second gear pair, resulting in two gear shift stages.

[0052] The electric drive is preferably controlled by taking into account, among other things, a quantity representing the rotational speed of the drive shaft 9 and a quantity representing the rotational speed of the intermediate shaft 10 as input variables. These can be, for example, the motor speed of the electric motor 3 and the wheel speed of the vehicle wheels 83, 84, from which the rotational speeds of the drive shaft 9 and the intermediate shaft 10 can be determined. Calculating the shaft speeds is important in order to synchronize the rotational speed of the drive shaft with that of the intermediate shaft using the electric motor 3. As a further input variable, the electronic control unit for controlling the electric drive receives control signals from the actuation arrangement 1, for example, which switching position is engaged. This is important, for example, so that the electric motor 3 only introduces torque into the drive arrangement 2 when the first or second switching position is engaged.The second gear shift stage is securely engaged.

[0053] An inventive method for controlling the actuating arrangement 1 can comprise the following steps: sensing a position signal P representing the position of the actuating element 50; sensing a force signal F representing the actuating force for moving the actuating element 50; and controlling the actuator drive 46 by means of the electronic control unit as a function of the position signal P and the force signal F. The control-related linking of position and force signals enables calibration of the actuating arrangement so that changes in position and tolerance occurring during operation can be taken into account for the control. The position of the switching sleeve 45 can be determined by means of the position sensor, which can be designed as a displacement or angle sensor.The force sensor can register all changes in axial force occurring during operation and assign them to a corresponding position of the switching sleeve 45.

[0054] To calibrate the arrangement, during a first clutch operation, an end position of the shift sleeve 45 is approached and detected by a sudden increase in the power signal. This is in Figure 11c ) recognizable as peak F6. The end position represents an end stop of the clutch unit 12 in the first or second coupling position. Simultaneously, a corresponding end position value P6, detected by the displacement sensor, is stored. During a subsequent clutch operation, the stored end position value can be taken into account when activating the actuator drive 46, such that the actuating element 50 is decelerated before reaching the end position. This ensures a high level of shifting comfort.

[0055] After reaching the end position P6, the actuating element 50 is moved a defined distance to a coupling position axially spaced from the end position. This coupling position is in Figure 12 The figure shows the slight retraction, indicated by an arrow. This retraction reduces frictional forces in the engaged state because axial play is established in the actuating assembly or clutch. The axial distance between the end position and the engagement position, or the distance by which the actuating element retracts, can be, for example, between zero and 1.0 mm. During a subsequent engagement process, the actuator drive 46 can be controlled such that the actuating element 50 is moved directly into the engagement position, i.e., stopped in the engagement position before reaching the end position.

[0056] According to another possibility arising from the calibration, the drive 46 can be controlled during the coupling process in such a way that the feed rate of the actuating element 50 is reduced before reaching the synchronization position, which is in Figure 9 It is shown that it is reduced.

[0057] If the relative speed difference between the clutch input part and the clutch output part has not fallen below a predetermined differential speed value after a specified period of time, the shifting or clutching process is aborted and the sliding sleeve is returned to the neutral position.

[0058] The following describes a clutch or switching process from the neutral position (N) to the first switching position (C1) using the illustrations in Figures 8 to 12. Figures 8 to 12Figure a) shows the clutch unit 12, figure b) shows a section of the clutch as a developed section, and figure c) shows the corresponding characteristic curve diagram. In the characteristic curve diagram, the upper line shows the position signal (P) of the first sensor 54, the second line the torque M of the electric motor 3 for driving the vehicle's drive axle, the third line the rotational speed n of the electric motor 3, and the lower line the forces F acting on the actuating element 50. The graphs shown in the figures were determined experimentally; however, the basic principle applies equally in reality. For the sake of simplicity, only some of the reference symbols are shown.

[0059] The Figures 8a) to 8cThe figures show the neutral position (N) of the arrangement. No gear is engaged. To synchronize the speeds between input part 42 and output part 43, the motor torque M or the motor speed n of the electric motor 3 is increased. This area is shaded gray in the diagram, with the increased value for motor torque labeled M1 and for motor speed n1. Subsequently, the coupling element 45 is moved by the actuating element 50, which is driven by the actuator drive 46, towards the coupling position (C1). During this movement, the sliding blocks engage the contact surface of the coupling element 45, which is designed as a sliding sleeve, and move it towards the desired gear.

[0060] In the Figures 9a) to 9cThe pre-synchronization is shown in Figure 1. The pressure pieces 62 act on the outer synchronizer ring 58 against the conical surface of the intermediate ring 60, which can also be called a friction ring. As a result of the speed difference between the sliding sleeve 45 and the output part 43, the outer synchronizer ring 58 is rotated, which in Figure 9b ) is clearly visible. The teeth of the sliding sleeve 45 are slightly offset in the circumferential direction relative to the teeth of the external synchronizer ring 58, so that the sliding sleeve 45 cannot be engaged as long as a speed difference exists. The described switching state is shaded gray in the diagram. The increased value for the forces F acting on the shift claw is visible and is marked F2. The corresponding sensor signal is shown as S2.

[0061] During the synchronization process, the sliding sleeve 45 is moved further, causing it to contact the chamfered ends of the sliding sleeve and the outer synchronizing ring 58. This initiates the main synchronization, which is not shown separately. During the main synchronization, the switching force is applied to the outer synchronizing ring 58 via the pressure pieces 62 and the sliding sleeve 45. The sliding sleeve cannot be engaged during the so-called sliding phase.

[0062] Upon reaching synchronization (S), which occurs in Figure 10 As shown, the frictional torque between the synchronizer rings drops to zero. This results in a corresponding reduction of the axial forces acting on the sliding sleeve 45, which in Figure 10c ) is marked with F3. The opening gear torque causes the outer synchronizer ring 58 to rotate backwards relative to the sliding sleeve 45 via the tooth helixes, which in Figure 10b) is recognizable. The sliding sleeve 45 can be moved further in this position towards the desired gear or coupling position. In doing so, the spring-loaded balls 63 of the pressure pieces 62 are pushed over by the sliding sleeve 45, thus completing the synchronization.

[0063] In the subsequent process step of the insertion of the teeth of the sliding sleeve 45 and the teeth of the output gear 43, the end-face tooth chamfers of the sliding sleeve meet the tooth chamfers of the output gear 43, which leads to a renewed increase in force, which in Figure 10b ) is recognizable and marked F4. The sliding sleeve 45 rotates the output gear 43 relative to the outer synchronizer ring 58. The circuit is free, which leads to a drop in the axial force (F5) and the positive engagement between the sliding sleeve teeth and the output gear teeth can be established. Figure 11Figure 1 shows this process step in which the sliding sleeve 45 is pushed onto the output gear 43. This establishes the power flow between the input gear 42 or the drive shaft 9 and the output gear 43. The direction of movement is indicated by an arrow.

[0064] As the sliding sleeve 45 is moved further, the end stop is reached, which is noticeable by a renewed increase in the forces F acting on the sliding sleeve 45 and is detected by the force sensor means. The increase in force is in Figure 11c ) marked with F6. After reaching the end stop, the shift fork 50 is moved slightly back into the clutch position, which can also be called the gear position, using the sliding block. This return movement, which occurs in Figure 12 The change, represented by a right-pointing arrow, occurs, for example, over a distance of 0.5 mm to 1.0 mm. The forces F on the shift fork decrease noticeably again, which in Figure 12c ) is marked with F7.

[0065] Upon reaching the coupling position C1, the power flow between input gear 42 via the sliding sleeve 45 and output gear 43, or the gear 14 rigidly connected to it, is closed. The electric motor 3 for the electric drive can then be energized, which is indicated by the increasing torque M8. Reference symbol list

[0066] 1 Actuator assembly 2 Drive assembly 3 Electric motor 4 Gearbox 5 Differential gearbox 6 Stator 7 Rotor 8 Motor shaft 9 Drive shaft 10 Intermediate shaft 11 Differential carrier 12 Clutch unit 13 14 First drive gear 15 First intermediate gear 16 Second drive gear 17 Second intermediate gear 18 Output gear 19 Ring gear 20 Bearing 21 Bearing 22 Shaft teeth 23 Shaft teeth 24 Bearing 25 Bearing 26 Housing 27 Radial shaft seal 28 First housing part 29 Second housing part 30 Connecting element 32 Bearing 33 Bearing 34 Bearing 35 Bearing 36 Radial shaft seal 37 Radial shaft seal 38 Differential gear 39 Side shaft gear 40 Side shaft gear 41 Pin 42 Input part 43 First output part 44 Second output part 45 Coupling element 46 Actuator drive 47 Converter unit 48 Spindle 49 Spindle sleeve 50 Shift fork 52 Sliding block 53 Ring groove 54 Sensor 55 Signal transmitter 56 Screw connection 57, 57' Synchronizing mechanism 58, 58' Outer ring 59, 59' Inner ring 60, 60' Intermediate ring 62 Pressure piece 63 Ball 64 Spring 65 Groove 66, 66' first ring 67, 67' Sleeve attachment 69, 69' Welded joint 70 Feed element 71 Radial gap 72, 72' First washer 73, 73' Second washer 74, 74' Retaining ring 75 Longitudinal bore 76 Transverse bore 77, 77' Transverse bore 78 Retaining ring 80 Vehicle axle 81 Side shaft 82 Side shaft 83 Wheel 84 Wheel A-axis C1, C2 Switching positions E-plane F-force M-torque N-neutral position n-speed P-position S-synchronizing position

Claims

1. A process of controlling an actuating assembly for a coupling in the driveline of a motor vehicle, wherein the actuating assembly comprises an actuator drive (46) for moving an actuating element (50) for actuating the coupling unit (12), wherein the process comprises the following steps: sensing a position signal representing the position (P) of the actuating element (50); sensing a force signal representing the operating force (F) required for shifting the actuating element (50); characterised by: linking a sensed position signal and an associated sensed force signal for determining an accurate position of the actuating element; controlling the actuator drive (46) by an electronic control unit (ECU) depending on the position signal and the force signal linked thereto.

2. Process according to claim 1, characterised in that in a first coupling procedure, an end position of the actuating element (45), which represents an end stop of the coupling unit (12), is sensed by an abrupt increase in the force signal (F6) and that an associated end position value (P6) is stored, and that in at least one later coupling procedure, the end position value is taken into account by the electronic control unit (ECU) when controlling the actuator drive (46) such that the actuating element (50) is braked before the end position is reached, wherein the end position value (P6) is defined in particular on the basis of a position signal sensed at the time of the abrupt increase on the force signal (F6).

3. Process according to claim 2, characterised in that, after reaching the end position, the actuating element (50) is moved by a defined path into a coupling position (C1, C2) which is axially spaced from the end position.

4. Process according to any one of claims 2 or 3, characterised in that, at a later coupling procedure, the actuator drive (46) is controlled such that the actuating element (50) is moved directly into the coupling position (C1, C2), i.e. is stopped in the coupled position before reaching the end position.

5. Process according to any one of claims 1 to 4, characterised in that the coupling unit (12) comprises a synchronising mechanism (58, 59, 60; 58', 59', 60') which, in a synchronising position (S) of the actuating element (50), adjusts a first rotational speed of a coupling input part (42) and a second rotational speed of a coupling output part (43, 44) relative to one another, wherein, during the coupling procedure, the actuator drive (46) is controlled such that the travel speed of the actuating element (50) is reduced before the synchronising position (S) is reached.

6. Process according to claim 5, characterised in that the travel speed of the actuating element (50) is again increased if a relative difference in rotational speed between the coupling input part (42) and the coupling output part (43, 44) drops below a predetermined value of rotational speed difference, and / or that the actuating element (50) is returned into a neutral position (N), if after a predetermined period, the relative difference in rotational speed is still greater than the predetermined value of rotational speed difference.

7. Process according to any one of claims 1 to 6, characterised in that< / b> the process step of sensing the position signal comprises at least one of the following sub-steps: sensing a path signal representing a path of the actuating element (50) and determining the position on the basis of the path signal; sensing a rotational signal representing a rotational movement of the actuator drive (46) and determining the position on the basis of the rotational signal.

8. Process according to any one of claim 1 to 7, characterised in that the actuator drive (46) for moving the actuating element (50) is an electric motor, wherein the process step of sensing the force signal comprises the following sub-steps: sensing the electric current of the electric motor and calculating the force (F) of the actuating element (50) on the basis of the amperage of the electric motor.

9. Drive assembly with a coupling unit in the driveline of a motor vehicle and with an actuating assembly (1) for actuating the coupling unit, wherein, by means of the actuating assembly (1), the coupling unit (12) is selectively adjustable into a coupling position (C1, C2) in which torque is transmitted between a coupling input part (42) and coupling output part (43, 44), and into a neutral position (N) in which the coupling input part (42) and the coupling output part (43, 44) are freely rotatable relative to one another, wherein the coupling unit (12) comprises a synchronising mechanism (58, 59, 60; 58', 59' 60') that effects an adjustment of rotational speed between the coupling input part (42) and the coupling output part (43, 44) before closing into the coupling position (C1, C2); wherein the actuating assembly comprises: an actuator drive (46) with a rotatingly drivable shaft; a rotation translation convertor (47) which converts a rotational movement of the shaft into a translatory movement of the actuating element (50); first sensor means (54, 55) which sense a position signal which represents the translatory movement of the actuating element (50); second sensor means which sense a force signal representing a force of the actuator drive (46);and an electronic control unit (ECU) for controlling the actuator drive (46), characterized in that the electronic control unit (ECU) is connected to the first sensor means (54) and to the second sensor means for linking a sensed position signal and a sensed force signal with each other for accurately determining the position of the actuating element (50) and for controlling the actuator drive (46).

10. Drive assembly according to claim 9, characterised in that the first sensor means (54, 55) comprise a path sensor which senses at least indirectly a movement of the actuating element (50), more particularly by means of a sensor target (55) fixed to the translation part (49), whose position is detectable by the first sensing means (54).

11. Drive assembly according to claim 9 or 10, characterised in that the first sensor means (54, 55) comprise an angle of rotation sensor which at least indirectly senses a rotational movement of the actuator drive (46), wherein the position of the actuating element (50) is determined on the basis of the sensed rotational movement of the actuator drive (46).

12. Drive assembly according to any one of claims 9 to 11, characterised in that the second sensor means comprise an electric current sensor which senses the electric current requirements of the actuator drive (46).

13. Drive assembly according to any one of claims 9 to 12, characterised in that the rotation translation convertor (47) comprises a threaded spindle with a spindle part (48) which is rotatingly drivable by the shaft, and a translation part (49) threadingly connected to the spindle part (48) which transition part (49) is guided relative to the housing (26) in a rotationally fixed and longitudinally movable way, so that a rotation of the spindle part (48) effects an axial movement of the translation part (49), wherein the actuating part (50) is axially fixed to the translation part (49).

14. Drive assembly according to any one of claims 9 to 13, characterised in that the coupling input part (42) is connected to a driveshaft (9) in a rotationally fixed way, and that the coupling output part (43, 44) is connected in a rotationally fixed way to a first drive gear (14) rotatably supported on the driveshaft (9).

15. Drive assembly according to any one of claims 9 to 14, characterised in that the coupling unit (12) comprises two coupling output parts (43, 44) and that a coupler (45) is provided in the form of a sliding sleeve which is held in a rotationally fixed and axially displaceable way relative to the coupling input part (42) and which for actuation is firmly connected to the actuating element (50) of the actuating assembly (1), wherein the coupler (45) is movable: into a neutral position (N) in which the coupling input part (42), the first coupling output part (43) and the second coupling output part (44) are freely rotatable relative to one another, or into a first coupling position (C1) in which the coupling input part (42) is connected to the first coupling output part (43) for transmitting torque, or into a second coupling position (C2) in which the coupling input part (42) is connected to the second output part (44) for transmitting torque.