Coupling Device for a Motor Vehicle

Abstract

A coupling device for a motor vehicle includes a first coupling element associated with a first rotatable part of the motor vehicle, and a second coupling element associated with a second rotatable part of the motor vehicle. The coupling device moves one or both of the first coupling element and the second coupling element into an intermediate position before a target rotational speed differential between the first and the second coupling elements is reached. Specifically, the target rotational speed differential is reached before the coupling device moves the first coupling element and the second coupling element into form-lockingly coupling to couple the first and second rotatable parts.

Claims

1-10: (canceled)

11. A coupling device for a motor vehicle having a first rotatable part and a second rotatable part, the coupling device comprising: a first coupling element associated with the first rotatable part, and a second coupling element associated with the second rotatable part, wherein the coupling device moves one or both of the first coupling element and the second coupling element into an intermediate position before a target rotational speed differential (3) between the first and the second coupling elements is reached, the target rotational speed differential (3) being reached before the coupling device moves the first coupling element and the second coupling element into form-lockingly coupling to couple the first and second rotatable parts.

12. The coupling device of claim 11, wherein the coupling device is moves the one or both of the first coupling element and the second coupling element into precisely one intermediate position (8) before the target rotational speed differential (3) is reached.

13. The coupling device of claim 11, wherein the intermediate position (8) is fixedly predefined by the coupling device.

14. The coupling device of claim 11, wherein the coupling device moves the one or both of the first coupling element and the second coupling element as a function of a speed differential between the first coupling element and the second coupling element before the target rotational speed differential (3) is reached.

15. The coupling device of claim 14, wherein the coupling device detects the speed differential and couples the first coupling element and the second coupling element when a limit speed (12) has been reached or fallen below.

16. The coupling device of claim 14, wherein the coupling device corrects, as the function of the speed differential, one or both of: movement of one or both of the first coupling element and the second coupling element; and the intermediate position (8) of one or both of the first coupling element and the second coupling element.

17. The coupling device of claim 11, wherein the coupling device detects a position of one or both of the first coupling element and the second coupling element.

18. The coupling device of claim 11, wherein the coupling device: detects an arising dog intermediate condition between the first coupling element and the second coupling element, wherein the arising dog intermediate condition is one of a dog clamping or a tooth-on-tooth position; and moves the one or both of the first coupling element and the second coupling element as a function of the arising dog intermediate condition.

19. The coupling device of claim 11, further comprising an actuator for moving the one or both of the first coupling element and the second coupling element.

20. A motor vehicle, comprising the coupling device of claim 11.

21. A method for coupling two coupling elements of a coupling device for a motor vehicle, the coupling device comprising a first coupling element having a first rotatable part of the motor vehicle, the coupling device further comprising a second coupling element having a second rotatable part of the motor vehicle, the method comprising: setting a target rotational speed differential (3) between the first coupling element and the second coupling element; moving one or both of the first coupling element and the second coupling element into at least one intermediate position (8) before the target rotational speed differential (3) is reached; and moving the first coupling element and the second coupling element to form-lockingly couple after the one or both of the first coupling element and the second coupling element is brought into at the least one intermediate position (8).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention is explained in the following on the basis of exemplary embodiments with reference to the figures. The figures are schematic views, wherein:

[0024] FIG. 1 shows an exemplary engagement process according to the prior art;

[0025] FIG. 2 shows an exemplary engagement process according to first exemplary aspects;

[0026] FIG. 3 shows an exemplary engagement process according to second exemplary aspects;

[0027] FIG. 4 shows an exemplary engagement process according to third exemplary aspects; and

[0028] FIG. 5 shows an exemplary engagement process according to fourth exemplary aspects.

DETAILED DESCRIPTION

[0029] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

[0030] FIG. 1 shows an exemplary engagement process of a coupling device according to the prior art. The schematic diagram shows a curve 1 of the rotational speed of the movable coupling element of the coupling device or of the speed differential between two coupling elements of the coupling device, and a curve 2 of the displacement travel of the at least one movable coupling element. The rotational speed according to curve 1 is adapted to a target rotational speed 3 in order to engage the coupling device. The target rotational speed 3 provides a certain, in particular minor, relative rotation between the two coupling elements. A movable dog and a coupling body, in particular, is usable as the coupling element, for example, at a wheel or a shaft of a transmission of the motor vehicle. Either the speed differential between the two coupling elements, which speed differential is to be reduced to the target rotational speed 3, is considered or, as shown, the rotational speed of one of the coupling elements, in particular a coupling element in the decoupled condition, is accelerable to a defined rotational speed, in particular on the input side, so that the target rotational speed sets in between the two coupling elements.

[0031] As shown, the rotational speed of the coupling element increases according to curve 1 in order to carry out the engagement process at a planned point in time, i.e., to reach the target rotational speed 3, in particular shortly before a synchronous speed 4 has been reached, in order to be able to engage the coupling device. The above-described engagement process or coupling process is plannable by a control device, for example, in conformance with a driving strategy or shift strategy, or the like. In order to reach the target rotational speed 3 at the appropriate point in time, the movable coupling element is activated at a point in time 5 or the coupling process is begun at the point in time 5. The movable coupling element therefore carries out a movement 6 starting at the point in time 5, wherein a response time and a time-of-flight of the movable coupling element initially elapse until the movable coupling element reaches the other coupling element. The response time indicates, in particular, the time that elapses until the movable coupling element begins to move, and the time-of-flight indicates how long the movable coupling element needs to reach the toothing of the other coupling element, in particular to reach a tooth-on-tooth position.

[0032] In the operating situation shown, a deviation 7 is represented, which changes the speed differential between the two coupling elements. For example, the deviation 7 is generated by a strong brake engagement, which results in a change in the rotational speed on the output side, i.e., the rotational speed of the particular other coupling element. Since the deviation 7 arises after the point in time 5, the movement of the movable coupling element has already been initiated, and so the coupling element is ultimately no longer stoppable. As a result, the target rotational speed 3 has not been reached when the toothing of the other coupling element is reached, and so the coupling process is not optimally performable.

[0033] In order to improve the coupling process, it is provided, as shown in FIGS. 2-5, to assume an intermediate position 8, in order to reduce or avoid effects and deviations. In the schematic diagrams from FIGS. 2-5, the rotational speed according to curve 1 and the actuating travel or the position of the movable coupling element according to curve 2 are plotted with respect to time. If a coupling process is to be carried out, the movable coupling element is initially moved to an intermediate position 8, which is situated between a starting position 9, in which the coupling device is completely disengaged, and an end position 10, in which the coupling device is completely engaged. Starting from the intermediate position 8, a tooth-on-tooth position 11 for the movable coupling element is considerably closer and, thus, is reachable considerably faster. In other words, the distance and the movement time in which deviations 7 (shown in FIG. 1) have a negative effect on the coupling process are considerably shortened.

[0034] In other words, the movable coupling element is already moved closer to the other coupling element, in order to subsequently carry out the coupling process and engage the coupling device, in particular upon exceedance of a limit speed 12 or upon falling below a defined limit value for the speed differential. A considerably shorter distance is to be covered between the intermediate position 8 and the tooth-on-tooth position 11 than from the starting position 9 into the tooth-on-tooth position 11.

[0035] FIG. 3 shows the method described above with reference to FIG. 2 and the above-described coupling process when a deviation 7 arises. If, for example, starting at the point in time 5, an engagement process is initiated by the movable coupling element being moved starting from the intermediate position 8 toward the corresponding further coupling element, a correction 13 of the actuating travel or of the position of the movable coupling element is performable if the deviation 7 arises. The correction 13 is represented in this example as a movement of the movable coupling element in the decoupling direction. In other words, in this example, the movable coupling element 7 is moved back in the direction of the starting position 9 to the intermediate position 8 due to the deviation 7. Finally, with the correction 13, the movement of the movable coupling element is able to be paused, decelerated, accelerated, or, as shown, reversed.

[0036] If, for example, after the point in time 5, the speed differential between the coupling elements is changed in an unplanned manner due to a strong brake engagement, as is also described with reference to FIG. 1, the coupling element is movable back to the intermediate position 8 until the limit speed is exceeded, instead of carrying out the coupling process. The movable coupling element is movable from the intermediate position 8, as described above, into the end position 10, so that the target rotational speed 3 is reachable upon engagement of the coupling device.

[0037] FIG. 4 shows the above-described method according to third example aspects. As shown, the movable coupling element is moved as a function of the speed differential between the two coupling elements. In a section 14 of the curve 2, it is apparent that the movable coupling element is movable in synchronism with the change in the speed differential between the coupling elements. This means an approach of the movable coupling element toward the further coupling element is also carried out during a synchronization of the two rotational speeds, i.e., during an adaptation of the speed differential in the direction of the target rotational speed 3. This means the movable coupling element is movable closer and closer to the further coupling element, provided the rotational speeds of the two coupling elements are synchronized or approach the target rotational speed 3. As shown in FIG. 4, the movable coupling element is therefore movable in the direction of the tooth-on-tooth position 11. The position, the speed, and the change in the position and the change in the speed of the movable coupling element is adaptable to the change in the speed differential.

[0038] This causes the movable coupling element to be moved toward the further coupling element precisely at the speed that is necessary to initiate an engagement of the coupling device at the point in time 5, so that the target rotational speed 3 is reachable as desired.

[0039] FIG. 5 shows other example aspects of the coupling process of the coupling device, wherein deviations 7 in the speed differential arise according to curve 1. The curve section 14 of the curve 2 is changeable according to corrections 13, in order to be able to flexibly respond to the arising deviations 7. The position of the movable coupling element is therefore controlled in a targeted manner by decelerating, accelerating, pausing, or reversing the movement of the movable coupling element, in order to always bring the coupling element in line with the change in the speed differential between the two coupling elements. If the speed differential adapts faster to the target rotational speed 3, the movement of the coupling element also takes place faster. If the speed differential changes more slowly or moves away from the target rotational speed 3, the movement of the movable coupling element is also able to be decelerated, paused, or reversed.

[0040] This means that the point in time 5, at which the engagement process is completely initiated, the displacement travel of the at least one movable coupling element is correctly selectable corresponding to the deviation 7, so that the actual exceedance of the limit speed 12 according to the correction 7 is usable as the point in time 5. The engagement process is therefore prevented from being carried out, even though the deviation 7 has resulted in a change in the speed differential, so that the engagement process is not sub-optimally performed, as in FIG. 1. Instead, the intermediate position of the coupling element is always selectable in line with the change in the speed differential. Therefore, the two coupling elements are movable toward each other and contact each other in the tooth-on-tooth position 11 precisely upon exceedance of the limit speed 12, so that an engagement process is performable once the target rotational speed 3 has been reached.

[0041] The coupling process and method described with reference to the figures are performable with a suitable coupling device. In some instances, the coupling device is an integral part of a motor vehicle. All advantages, details, and features are therefore transferrable to the motor vehicle and the coupling device. The advantages, details, and features shown in the individual exemplary embodiments are arbitrarily interchangeable with one another, combinable with one another, and transferrable to one another.

[0042] Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

[0043] 1, 2 curve [0044] 3 target rotational speed [0045] 4 synchronous speed [0046] 5 point in time [0047] 6 movement [0048] 7 deviation [0049] 8 intermediate position [0050] 9 starting position [0051] 10 end position [0052] 11 tooth-on-tooth position [0053] 12 limit speed [0054] 13 correction [0055] 14 section