CN114060431A - Method for actuating a shift device and shift device for a motor vehicle transmission - Google Patents

Abstract

In a shifting device (26) and a method for operating the shifting device (26), an axial force is applied to the clutch by means of an operating element (56) and is continuously increased. The friction clutch (38) is first closed, so that the rotational speeds of the second plate carrier (30) and the clutch body (36) are matched. The second plate carrier (30) is moved in the axial direction (A) to engage a form-locking element of the form-locking clutch (50). The actuating element (56) acts on the second sheet support (30) in a force transmission path which is formed exclusively by the rigid component. When a tooth-to-tooth position occurs between the two form-locking elements, the multi-plate clutch (34) is closed by further increasing the axial force and causing a relative rotation between the second plate carrier (30) and the clutch body (36) until a tooth-to-gap position is reached between the two form-locking elements.

Description

Method for actuating a shift device and shift device for a motor vehicle transmission

Technical Field

The invention relates to a method for actuating a shifting device of a motor vehicle transmission and to a shifting device for a motor vehicle transmission, in particular a fully automatic manual transmission.

Background

For force transmission, in addition to manual shifting gearboxes, automatic transmissions, in particular stepped full-automatic transmissions with hydrodynamic torque converters and planetary transmissions, are also used in vehicle technology.

Such fully automatic multi-speed transmissions are used as powershift transmissions with uninterrupted tractive power, in which the power flow is effected via planetary gear sets and the shifting is effected by coupling or releasing individual planetary gear set elements. The coupling of the individual planetary gearset elements is currently effected primarily by means of disk clutches and disk brakes, which must meet the maximum torque to be transmitted and accordingly comprise a large number of friction points or disks for torque transmission. Due to the large number of friction points, the undesirable drag torque in the decoupled state is very high and has a negative effect on the transmission efficiency.

For this reason, it has already been proposed, for example, in DE 102016114271 a 1: one of the plate carriers is coupled to a rotatable transmission component, for example a transmission shaft, by synchronization by means of friction rings. The friction ring is part of a friction clutch, which comprises only the friction ring and the mating friction surface. In the synchronous decoupled state, drag torques also occur, which are significantly lower due to the significantly smaller friction surfaces of the friction clutch compared to the plate clutch. In the decoupled state of the transmission device, i.e. with the disk clutch open and synchronously decoupled, the relative rotation only or at least mainly takes place in the synchronous region and no or almost no longer in the region of the disk clutch due to the low drag torque, so that the transmission efficiency is increased. However, switching devices of this type are usually complicated to construct, which additionally increases the production costs.

Disclosure of Invention

The purpose of the invention is: the drag torque of the plate clutch is reduced and a comfortable switching behavior is achieved while maintaining a small number of individual components, while nevertheless maintaining the full power switching capability of the plate clutch.

The object is achieved by a shifting device for operating a motor vehicle transmission and a method for closing a drive train which transmits torque, wherein the motor vehicle transmission comprises a friction clutch, a form-locking clutch and a plate clutch. The plate clutch has a first plate carrier and a second plate carrier, while the positive clutch has a first positive-locking element, which is arranged on the clutch body, and a second positive-locking element, which is connected to the second plate carrier and can be brought into and out of positive engagement with the first positive-locking element in order to selectively transmit torque. The method comprises the following steps:

applying an axial force to the clutches, i.e. friction, form-locking and plate clutches, via the actuating element and continuously raising them,

closing the friction clutch, thereby matching the rotational speeds of the second plate carrier and the clutch body,

-moving the second sheet support in the axial direction to engage the second form-locking elements into the first form-locking elements,

the axial force is further increased such that the friction torque of the closed disk clutch is greater than the friction torque of the closed friction clutch, thereby causing a relative rotation between the second disk carrier and the clutch body until a tooth-to-space position is reached between the two form-locking elements, thereby reducing the friction torque of the disk clutch such that the friction torque of the disk clutch is less than the friction torque of the closed friction clutch, so that the rotational speeds of the second disk carrier and the clutch body are matched again. The second form-fitting element is then engaged into the first form-fitting element of the form-fitting clutch by the axial force further exerted by the actuating element, and the multi-plate clutch is closed again by the action of the axial force of the actuating element.

The shifting device is designed such that, when the tooth-to-space position is reached, the already compressed disk set is released again and the already closed disk clutch can be opened at least partially again. Here, the friction torque of the plate clutch is reduced again. If both clutches are closed, the friction torque of a friction clutch, which usually has only two friction surfaces, is smaller than the friction torque of a multi-plate clutch, so that the second plate carrier is connected to the first plate carrier via the multi-plate clutch and is driven at its rotational speed in the circumferential direction (mitnehmen). However, if the plate clutch is released again, its friction torque drops again below the friction torque of the still closed friction clutch. This results in: the second plate carrier is now coupled again to the clutch body in the circumferential direction. The rotational speeds of the second plate carrier and the clutch body are thereby matched again, and the engagement of the form-locking element is always carried out with the rotational speeds matched. The method according to the invention also has the advantage that, since the rotational speed of the second plate carrier is matched again to the rotational speed of the clutch body by the friction clutch, the engagement of the form-locking element is not time-critical and is less noisy, which significantly increases the switching comfort for the user.

The acting axial force is preferably applied to the second leaf support exclusively and directly by the actuating element and without establishing a spring preload. The use of a spring for effecting the coupling movement of the second form-locking element into the first form-locking element is therefore dispensed with. This results in: without the action of such a spring prestressed in the axial direction, the sheet pack can be loosened and the rotational speed can be adapted again without an undesired acceleration of the engagement movement.

If the form-fitting clutch is in the tooth-to-space position directly when the engagement is initially attempted, the engagement takes place directly after the first rotational speed adaptation of the second plate carrier to the clutch body and before the plate clutch is closed.

The first plate carrier corresponds here to the plate carrier whose plates are connected in a force-transmitting manner to the first transmission component, while the second plate carrier corresponds to the plate carrier on which the friction clutch with the clutch body is arranged. The clutch body is connected with the second transmission member.

The adaptation of the rotational speeds is understood to mean a process, after which the rotational speeds of the relevant components for the important aspects are identical.

In general, the actuating element is moved axially with increasing axial force, wherein, starting from an unactuated starting position in which all three clutches are open, the shifting device first assumes a synchronous position in which the friction clutch is in the activated state, then assumes a positive-locking position in which the first and second positive-locking elements are engaged with one another, and finally assumes a closed position in which the first and second plates of the multi-plate clutch are frictionally engaged.

In the inoperative starting position, the plate clutch is open, so that the plates of the second plate carrier are not coupled with the first plate and the first transmission member in the circumferential direction.

In the form-locking position, the plates of the second plate carrier are coupled in the circumferential direction with the clutch body via the form-locking clutch, but the second plate carrier is not yet coupled with the first plate carrier.

In the closed position of the multi-plate clutch, the plates of the second plate carrier are finally coupled in the circumferential direction via a frictional connection to the plates of the first plate carrier and thus also to the first transmission component, wherein a force-locking connection is obtained via the form-locking clutch between the clutch housing and thus the second transmission component connected thereto and the first transmission component.

In the starting position, the drag torque between the clutch body and the first plate carrier, and thus between the second transmission component and the first transmission component, is significantly reduced as compared to a pure plate clutch, due to the disengaged friction clutch and the disengaged form-locking clutch.

In a shifting device for a motor vehicle transmission, which is particularly suitable for carrying out the above-described method, a first transmission component connectable to a second plate carrier and a second transmission component connected to a clutch body are provided, wherein the transmission components are rotatable relative to one another about a transmission axis. A friction clutch is provided, which comprises a friction ring which is connected in a rotationally fixed and axially displaceable manner in the circumferential direction to the second plate carrier or the clutch body and which has a conical friction surface and a counter-friction surface which interacts in a rotationally fixed manner with the clutch body or the second plate carrier and can be brought into contact with the friction ring by displacing the friction ring. Furthermore, a multi-plate clutch is provided, which comprises a plurality of second plates arranged on the second plate carrier, which are connected to one another in a rotationally fixed manner and axially displaceable manner in the circumferential direction, and a plurality of first plates coupled to the first transmission component, which are connected to one another in a rotationally fixed manner and axially displaceable manner in the circumferential direction, wherein the first plates and the second plates are arranged one behind the other in the axial direction in an alternating manner. Furthermore, a form-locking clutch is provided, which comprises a first form-locking element arranged on the clutch body and a second form-locking element arranged on the second plate carrier, wherein the first form-locking element and the second form-locking element are axially engaged with each other and can therefore be brought into a form-locking connection. Furthermore, an actuating element is provided which exerts an axial force on the second plate carrier in order to close the friction clutch, the form clutch and the plate clutch, wherein the actuating element acts on the second plate carrier on a force transmission path which is formed solely by the rigid component.

The force transmission between the actuating element and the second plate carrier takes place without intermediate action of the spring force and without spring pretensioning of the second plate carrier in the direction of the clutch body. As already mentioned, this allows the plates of the first and second plate carrier, which are already in frictional connection, to be released again only when the tooth-to-tooth position is reached under the influence of the axial force exerted by the actuating element that has just been present when the two teeth or claws of the form-fitting element meet one another in the tooth-to-tooth position, which leads to a renewed rotational speed adaptation by the friction clutch and enables a less time-critical and gentle engagement of the form-fitting clutch.

The force transmission path is realized, for example, directly from the actuating element to the second sheet support or via one or more rigid connecting pieces connected between them.

Locking teeth are usually not provided on the friction ring, so that the friction clutch is not designed for locking synchronization.

The friction clutch preferably has only friction surfaces on the friction ring and the mating friction surfaces.

The second plate carrier is usually provided with an uncoated steel plate, while the first plate is designed as a friction plate to which friction linings are applied. The reverse arrangement is of course also possible.

As is generally known, the actuating element can be, for example, a hydraulically actuated piston. The restoring of the actuating element can be effected, for example, by a separate piston restoring spring which acts on the actuating element in the direction opposite to the force transmission direction.

All return springs should act against the axial force of the actuating element, so that no spring element acting in the axial force direction is provided.

The first plate carrier is typically connected to a first transmission component, while the second plate carrier is connected to a second transmission component via a clutch body.

The first or second transmission component is, for example, configured as a transmission shaft that is rotatable about a transmission axis, or is firmly connected to such a transmission shaft. The further transmission component can form a transmission housing which cannot rotate relative to one another or be firmly connected to such a transmission housing, or can also form a further transmission shaft which can rotate about a transmission axis or be firmly connected to such a further transmission shaft.

The two separate transmission shafts, which are in this case in particular coaxially arranged transmission shafts of different planetary gear sets, can be speed-matched by means of a shifting device.

The shifting device is used in particular in fully automatic manual transmissions.

The shifting device can also be used as a brake, which can brake the rotatable transmission shaft and can be locked in rotation relative to the housing. A disk clutch forms a disk brake in the strict sense.

The first form-locking element should be formed in a fixed manner, for example in one piece, with the clutch body.

Preferably, the second form-locking element is firmly, for example integrally, connected with the second sheet support.

The two form-locking elements can be designed in particular as toothing of a dog clutch, wherein claw-like teeth, in particular crenellated claws, and the sound of the gaps provided between the teeth alternate along the circumference.

In a possible variant, the second positive-locking element on the second plate carrier forms an angled claw ring (Klauenkranz) which is connected axially to the axially innermost of the second plates, i.e. the second plate closest to the clutch body.

In a further possible variant, the second form-locking element is designed as an axially projecting free end of a linearly extending bridge on the second sheet support.

In particular, in this variant, it is conceivable: the first form-locking element on the clutch body is formed as a window in the annular disk of the clutch body.

In a further variant, the form-locking element is formed by an axial projection in a radially extending bridge.

The exact shape and the number of first and second form-locking elements are hereby at the discretion of the person skilled in the art.

Preferably, an annular spring is arranged between the second plate carrier and the friction ring, which annular spring is loaded toward the second plate carrier in the direction of the actuating element and is prestressed when the actuating element is moved axially, in particular the annular spring is the only spring element present between the second plate carrier and the clutch housing.

When the actuating element exerts an axial force on the second plate carrier and the friction clutch is to be closed, the annular spring transmits an axial force, the so-called synchronizing force, to the friction ring.

However, the annular spring should be designed such that it does not pretension the second plate carrier axially in the direction of the positive connection toward the clutch body.

The annular spring is preferably located in the force flow between the actuating element and the friction ring.

It is possible that: the mating friction surface is directly formed on the clutch body. In this case, the friction ring is arranged on the plate carrier so as not to be rotatable relative thereto. This arrangement can of course also be reversed, in which the friction ring is connected to the clutch body in a rotationally fixed manner.

In a possible variant, a rigid connection is provided, to which the actuating element acts axially. The connecting element can in particular be axially displaceable in this case towards the second sheet support.

For example, an annular spring is located between the connector and the friction ring.

The second plate carrier can be used both as a radially inner plate carrier (i.e. a plate carrier carrying the plates fastened on the radially inner side) and as a radially outer plate carrier (i.e. a plate carrier carrying the plates fastened on the radially outer side) of the plate clutch, depending on the specific design of the conversion device.

If the second plate support is the radially inner plate of the two plate supports, the friction ring is preferably arranged radially inside the second plate support. In a possible embodiment, the friction ring is located radially inside the second plate carrier and is arranged on the second plate carrier or the clutch body so as to be axially displaceable, but not so as to be rotatable relative to one another in the circumferential direction.

If the second plate support is the radially outer of the two plate supports, in an alternative possible embodiment, the friction ring is located radially outward of and surrounds the second plate support. In this case, one of the second plates can have a friction cone surface which interacts with the friction ring and forms the mating friction surface.

In this case, however, the friction ring also interacts with the clutch body. For this purpose, the clutch body can extend axially on all plates of the multi-plate clutch radially outside the plates.

In one variant, the second sheet metal support can have a central region extending axially with respect thereto, which central region has a circumferential recess in cross section, the two sides of which are provided on the radially inner side with annular springs. The edge of the recess serves both for transmitting the axial force exerted by the actuating element on the second leaf support to the annular spring and for acting as a reaction surface of the annular spring for transmitting the axial force to the second leaf support. It also holds the annular spring in the desired axial position.

Drawings

The invention is described in detail below with the aid of a number of embodiments with reference to the accompanying drawings. In the drawings:

FIG. 1 shows a transmission schematic of a fully automatic multi-speed transmission having a plurality of shift devices according to the present invention;

fig. 2 shows a schematic cross-sectional view of a conversion device according to a first variant of the invention;

fig. 3 shows a schematic cross-sectional view of a conversion device according to a second variant of the invention;

fig. 4 shows a schematic cross-sectional view of a conversion device according to a third variant of the invention;

fig. 5 shows a schematic cross-sectional view of a conversion device according to a fourth variant of the invention;

fig. 6 shows a schematic cross-sectional view of a conversion device according to a fifth variant of the invention;

fig. 7 shows a schematic cross-sectional view of a conversion device according to a sixth variant of the invention;

fig. 8 shows a perspective view of a portion of the transition device shown in fig. 7.

Detailed Description

Fig. 1 shows an electrohydraulic fully automatic motor vehicle transmission 10, which is a multi-speed transmission having a torque converter 12, four planetary gear sets 14 and a schematically illustrated transmission housing 16. Furthermore, a drivetrain is provided, which has a drive shaft 18, a driven shaft 20 and a plurality of transmission shafts 24, wherein the components of the planetary transmission are also referred to herein as transmission shafts 24. The transmission shafts 24 are assigned to the respective planetary gear sets 14 and are arranged coaxially with one another.

This arrangement of the transmission elements is to be understood as an example only and does not limit the invention described below to this embodiment.

The motor vehicle transmission 10 also has a plurality of shifting devices 26, which can be hydraulically actuated and which can usually connect the first transmission member 25 to the second transmission member 27 in a torque-transmitting manner. The shifting device 26 can, for example, couple the transmission shaft 24 to another transmission shaft 24 or to the transmission housing 16 (and correspondingly also decouple it again), wherein the transmission shaft 24 or the transmission housing 16, depending on the selected combination, each form a first or a second transmission component 25, 27.

In other words, the first transmission component 25 or the second transmission component 27 is configured here as a transmission shaft 24 that is rotatable about a transmission axis a or is firmly connected to such a transmission shaft 24. The respective other transmission component forms a transmission housing 16 that cannot rotate relative to one another or is firmly connected to such a transmission housing 16. Alternatively, the further transmission component is a further transmission shaft 24 which is rotatable about the transmission axis a or is firmly connected to such a further transmission shaft 24.

If the shift device 26 couples the transmission shaft 24 with the transmission housing 16, it acts as a brake device, while the shift device 26 coupling the two transmission shafts 24 with each other is also referred to as a clutch device. In the present exemplary embodiment, six shifting devices 26 are provided (this should not be understood as limiting), wherein for example three shifting devices 26 are designed as braking devices and for example three shifting devices 26 are designed as clutch devices. According to fig. 1, two brake devices and one clutch device are in the coupled state (indicated by hatching) and one brake device and two clutch devices are in the decoupled state.

The transmission ratios between the drive shaft 18 and the output shaft 20, which correspond to the individual gears of the motor vehicle transmission 10, are then obtained by different shifting combinations of the shifting device 26.

Since the general construction and functional manner of a fully automatic multi-speed transmission is already known from the prior art, it will not be discussed further and only the structural construction and function of the shifting device 26 according to the invention will be described in detail hereinafter.

Fig. 2 to 8 show different variants of the conversion device 26.

The axial direction a shown in fig. 2 to 8 coincides with the variator axis, also denoted a hereinafter.

Fig. 2 shows a first variant of the conversion device 26.

This first variant has a first plate carrier 23 (shown schematically in fig. 2 and 7) to which a first plate 28 is fastened in a rotationally fixed manner but displaceable in the axial direction a, and a second plate carrier 30 to which a second plate 32 is fastened in a rotationally fixed manner but displaceable in the axial direction a, wherein the first and second plates 28, 32 together form a plate clutch 34. The first and second plates 28, 32 are alternately arranged axially one after the other. In this example, the first plate 28 is configured as a friction plate and the second plate 32 is configured as a steel plate.

In this modification, the second sheet support 30 is one of the two sheet supports located on the inner side with respect to the radial direction r.

The first plate carrier 23 is firmly connected to the first transmission component 25, while the second plate carrier 30 is couplable and decouplable to the first and second transmission components 25, 27.

A clutch body 36 is arranged on the second transmission component 27 and can interact with the second plate carrier 30 via a friction clutch 38. The friction clutch 38 synchronizes the rotational speed of the clutch body 36 and the second plate carrier 30.

The friction clutch 38 comprises a friction ring 40 with a conical friction surface 42, which is connected in a rotationally fixed and axially displaceable manner to the second plate carrier 30 in the circumferential direction, and a conical counter-friction surface 44, which is formed directly on the clutch housing 36.

The arrangement can of course also be reversed, so that the mating friction surface 44 is arranged on the second plate carrier 30 and the friction ring 40 is arranged on the clutch body 36 in a rotationally fixed but axially displaceable manner.

In this example, the friction ring 40 is disposed radially inward of the second sheet support 30. The friction surface 42 is here directed radially inward, while the mating friction surface 44 is located radially inward of the friction ring 40.

A single annular spring 46 is arranged between the friction ring 40 and the second plate carrier 30 and is further prestressed when the second plate carrier 30 is moved in the axial direction a in the direction of the clutch body 36. The annular spring 46 transmits an axial force, the so-called synchronizing force, to the friction ring 40.

In this example, the second sheet support 30 acts on the annular spring 46 via a rigid connection 48. The connecting element 48 bears radially against the second plate carrier 30 and is centered there, in particular on the inner diameter, but can be moved in the axial direction. The connection of these components is effected in the circumferential direction, for example via a projection on the connecting piece 48 and a recess in the basin (Topf) of the second sheet support 30, so that there is rotational entrainment in the circumferential direction.

In this variant, the annular spring 46 is the only spring element present between the second plate carrier 30 and the clutch body 36.

As a third clutch, a form-locking clutch 50 is provided in the changeover device 26. The form-locking clutch is formed between a first form-locking element 52 on the clutch body 36 and a second form-locking element 54 on the second plate carrier 30.

In this example, the first and second positive locking elements 52, 54 are formed by castellated teeth which can engage one another and thus form a dog clutch. In the variant shown in fig. 2, the second form-locking element 54 is formed as a claw ring integrally connected to the second plate carrier 30, which claw ring is arranged on the radially outer end of the plate 32 of the plate carrier 30 which is closest to the clutch body 36 in the axial direction. The sheet 32 is here turned integrally into the remaining second sheet support 30.

In this variant, the first form-locking element 52 is designed as a toothing on the outer edge of the annular disk 55 of the clutch body 36.

The friction clutch 38, the form-fitting clutch 50 and the plate clutch 34 are closed in succession by an axial force F which is exerted by actuation of the actuating element 56 acting in the axial direction a on the second plate carrier 30. The actuating element 56 may comprise an axial bearing 58, which enables force transmission when shifting or when holding the plate clutch 34 in the closed state with a rotational speed difference. The effect on the axial end of the connecting piece 48 is achieved in the example of fig. 2.

The actuating element 56 can be realized in a known manner by a hydraulically actuated piston. Instead of hydraulic actuation, an electric actuation of the switching device 26 may of course alternatively be considered.

In the example of fig. 2, the force F acts directly on the connecting piece 48 and via the annular spring 46 on the friction clutch 38 or the conical friction ring 40. In parallel with this, when the elastic force of the ring spring 46 is exceeded, the force F acts on the sheet support 30.

The first transmission component 25 is connectable to the second transmission component 27 in a torque-transmitting manner via the friction clutch 38, the form-locking clutch 50 and the plate clutch 34.

To achieve this and to actuate the shifting device 26 to close the torque-transmitting drive train, the actuating element 56 is actuated such that it exerts a force F acting in the axial direction a on the multi-plate clutch 34 and thus also starts to move the second plate carrier 30 in the direction of the clutch body 36.

The actuating element 56 acts on the rigid connecting piece 48, which in turn acts on the annular spring 46, which acts on the friction ring 40 and moves it in the axial direction a toward the clutch body 36, so that the friction surfaces 42 come into contact with the mating friction surfaces 44, which closes the friction clutch 38.

A force-locking connection is thereby produced between the second plate carrier 30 and the clutch body 36 (and thus also the second transmission component 27, which is not considered further below).

This has the result that: the rotational speed of the second plate carrier 30 matches the rotational speed of the clutch body 36 until the second plate carrier 30 and the clutch body 36 rotate together at the same rotational speed.

The form-locking clutch 50 and the plate clutch 34 are still open at this point.

By further increasing the axial force F by the actuating element 56, the second plate carrier 30 is moved further in the direction of the clutch body 36 in order to engage the second form-locking elements 54 between the first form-locking elements 52 and to close the form-locking clutch 50.

If the first and second form-locking elements 52, 54 meet each other in the tooth-to-gap position, the two form-locking elements 52, 54 are pushed into each other in the axial direction a to such an extent that the form-locking clutch 50 is closed, whereby the second plate carrier 30 is connected to the clutch body 36 in a form-locking manner in the circumferential direction.

However, if at this point the first and second positive locking elements 52, 54 are arranged relative to one another such that they meet one another in the tooth-to-tooth position and the positive locking elements 52, 54 cannot be engaged with one another, the axial force F is increased further by the actuating element 56 and the axial force on the multi-plate clutch 34 is increased, as a result of which the torque of the multi-plate clutch 34 is also increased and the multi-plate clutch 34 is closed.

The friction torque of the closed plate clutch 34 is now greater than the friction torque of the still closed friction clutch 38. Thus, the action of the plate clutch 34 dominates and relative rotation between the second plate carrier 30 and the clutch body 36 is again produced due to the difference in the acting friction torques that exist.

However, as soon as the first and second form-locking elements 52, 54 have reached the tooth-to-hole clearance position as a result of this relative rotation, the sheet pack is released again, whereby the friction torque of the multi-plate clutch 34 becomes smaller again than the friction torque of the still closed friction clutch 38. A renewed rotational speed adaptation between the second plate carrier 30 and the clutch body 36 therefore takes place, but it is now ensured that the two form-locking elements 52, 54 are in the tooth-to-space position. The always present axial force F exerted by the actuating element 56 now engages the second form-locking elements 54 between the first form-locking elements 52.

In the force flow between the second plate carrier 30 and the clutch body 36, no spring element is provided which pretensions the second plate carrier 30 in the direction of the clutch body 36. The second form-locking element 54 is therefore also not prestressed in the direction of the clutch body 36, and the engaging movement of the form-locking clutch 50 is only carried out when the tooth-to-space position between the form-locking elements 52, 54 is correctly reached.

If the form-fitting clutch 50 is closed, the multi-plate clutch 34 is closed again by further axial movement of the second plate carrier 30 as a result of the axial force F exerted by the actuating element 56.

In this state, the switching device 26 is closed, and the first transmission member 25 is torque-transmitting connected with the second transmission member 27.

Starting from the non-actuated starting position, the shifting device 26 first assumes the synchronization position, then the form-locking position, and finally the closed position of the multi-plate clutch 34. In the non-actuated starting position, the multi-plate clutch 34 is open, so that the second plate 32 of the second plate carrier 30 is not coupled in the circumferential direction to the first plate 28 and the first transmission component 25. In the form-locking position, the second plate carrier 30 and accordingly also the second plate 32 are coupled in the circumferential direction via the form-locking clutch 50 to the clutch body 36, but not yet to the first transmission component 27, since the plate clutch 34 is still open. Only in the closed position of the plate clutch 34 is the second plate 32 of the second plate carrier 30 coupled in the circumferential direction via a frictional connection with the first plate 28 of the first plate carrier and thus also with the clutch member 36 and the first transmission component 25.

Prior to actuating the actuating element 56, the friction clutch 38, the form-fitting clutch 50 and the multi-plate clutch 34 are disengaged, and the second transmission member 27 is not connected in a force-fitting and torque-transmitting manner to the first transmission member 25.

In the non-actuated, axial starting position of the actuating element 56, the friction ring 40 and the mating friction surface 44 of the clutch housing 36 are in the so-called ventilation position, in which the friction surface 42 of the friction ring 40 is spaced apart from the mating friction surface 44.

Furthermore, in the non-actuated starting position of the actuating element 56, the first and second webs 28, 32 which axially adjoin one another are also ventilated, i.e. axially spaced apart from one another.

To open the switching device 26, the actuating element 56 is reset against the previous actuating direction, so that the axial force F is cancelled. This can be done, for example, by means of a spring (not shown) which acts on the actuating element 56. Alternatively, it is also conceivable: the operating element 56 is hydraulically reset.

By axial resetting of the actuating element 56 and resetting of the connecting element 48, the multi-plate clutch 34 is opened. This process is supported by the return of the annular spring 46. The form-locking clutch 50 is also disengaged and the first and second form-locking elements 52, 54 are disengaged and the friction ring 40 is released from the mating friction face 44 on the clutch body 36.

As soon as the actuating element 56 has reached its non-actuated, axial starting position again, all friction parts of the switching device 26 can be separated from one another again in the existing axial gap or ventilated.

Even in the ventilating position of the friction clutch 38, the plate clutch 34, drag torques occur at different rotational speeds between the first transmission component 25 and the second transmission component 27, which drag torques are, however, significantly lower than those of a pure plate clutch due to the significantly smaller friction surfaces of the friction rings 40. Correspondingly, in the starting position of the shifting device 26, a relative rotation takes place at least predominantly within the friction clutch 38. The first plate 28 is moved at least largely synchronously with the second plate 32 due to the drag torque in the (open) multi-plate clutch 34, so that in the starting position of the shifting device 26 only a small drag torque of the friction clutch 38 occurs, which has a positive effect on the transmission efficiency.

Fig. 3 shows a variant of the just described conversion device 26. In contrast to the above-described embodiment, the second form-locking element 54 on the second plate carrier 30 is formed here by the free end of an axially extending bridge on the second plate carrier 30, while the first form-locking element 52 is formed as a window in an annular disk 55 extending radially on the clutch body 36.

However, the form-fitting clutch 50 functions in the same manner as described for the first variant.

As a further difference, the second sheet support 30 has, radially inside the second sheet 32, a central region extending axially with respect thereto, in which a circumferential radial recess 60 is provided. One annular spring 46 is provided on each side of the recess 60, and the two annular springs 46 are located radially inward of the second sheet bearing 30 and supported on the end of the recess 60.

In addition, the actuating element 56 acts here directly on the plate 32 of the second plate carrier 30 adjacent to the actuating element 56, without a rigid connecting piece 48 being connected between them. The operating element 56 transmits the switching force to the second sheet support 30 via the annular spring 46 axially closer to the operating element 56 (hereinafter also referred to as axially inner annular spring 46). The maximum axial force acting on the friction clutch 38 can be set by the spring force of the two annular springs 46 and the ramp angle of the recesses 60 before the disk clutch 34 is closed by the axially moving axially inner annular spring 46.

The principle structure and the function are the same as those of the first modification described above.

In a third variant shown in fig. 4, the switching device 26 has an inclined contact surface 62 for one or the other of the annular springs 46 on the actuating element 56.

In this variant, the actuating element 56 also acts on the first friction lining 32 of the second plate carrier 30 as in the second variant. Unlike the second variant, the chamfer 56 for the axially inner annular spring 46 is provided on the axially innermost plate 32. The closure of the friction clutch 48 and the plate clutch 34 can be adjusted by the angle of the two annular springs 46 and the ramps.

As a further difference from the first variant, the first and second form-locking elements 52, 54 of the form-locking clutch 50 are formed by alternating axial projections and slots or windows in the second of the second plates 32 closest to the clutch body 36 and in the annular disk 55 of the clutch body 36.

For this variant, the principle structure and function are also the same as for the first variant described above.

In a fourth variant shown in fig. 5, the rigid connecting piece 48 is placed on a free end 64 of the second plate carrier 30 which is angled radially inward and points toward the actuating element 56 and does not extend as far as the friction ring 40. In contrast to the second variant, two inwardly bent tabs are provided in the second plate carrier 30, against which the annular spring 46 rests. The second plate carrier 30 here has no channel (Durchgriff) for the axially innermost friction plate 32. The axial force is directed via the connection 48 to the friction clutch 38.

Alternatively, an axially extending single spring element 46, for example a helical spring, may be provided, which extends between the connection 48 and the friction ring 40. The ramp or bevel of the annular spring 46 may thus be omitted.

In a fifth variant shown in fig. 6, the second of the second plates 32, which is formed by the second plate carrier 30 and is closest to the clutch body 36, extends radially inward to such an extent that it forms a guide 66 for the axially rear friction ring 40. Furthermore, the second plate carrier 30 is formed in multiple parts.

For this variant, the principle structure and function are also the same as for the first variant described above.

All features of these variants can be freely combined with each other or interchanged with each other, at the discretion of the person skilled in the art.

In a sixth variant shown in fig. 7 and 8, the friction ring 40 is located radially outside the second plate carrier 30, in contrast to the embodiments discussed so far. In this case, the second sheet support 30 also constitutes the radially outer one of the two sheet supports. Also exemplarily shown in these figures is a first sheet support 23.

In this variant, the friction ring 40 is connected in a rotationally fixed and axially displaceable manner to a clutch body 36 which extends with a section 72 radially outside the second plate carrier 30.

The mating friction surface 44 is formed here on the second of the second plates 32 which is axially closest to the actuating element 56.

In this variant, the friction ring 40 also acts directly between the second plate carrier 30 and the clutch body 36.

As in the second variant, an axial bridge is formed on the second plate carrier 30, the free end of which forms a second form-locking element 54 that engages in a window, here designated as the first form-locking element 52, in an annular disk 55 on the clutch body 36.

Only one single annular spring 46 is provided as a single spring element between the second plate carrier 30 and the clutch body 36, which annular spring 46 is arranged axially between the annular disk 55 of the clutch body 36 and the friction ring 40.

For this variant, the remaining principle structure and function are also the same as for the first variant described above.

Claims (11)

1. Method for operating a switching device (26) of a motor vehicle transmission (10) and for closing a drive train transmitting torque, wherein the motor vehicle transmission (10) comprises a friction clutch (38), a form-locking clutch (50) and a multi-plate clutch (34),

wherein the plate clutch (34) has a first plate carrier (23) and a second plate carrier (30), and

the form-locking clutch (50) having a first form-locking element (52) which is arranged on the clutch body (36) and a second form-locking element (54) which is connected to the second plate carrier (30) and can be brought into and out of form-locking engagement with the first form-locking element (52) in order to selectively transmit torque,

the method has the following steps:

-applying an axial force to the clutch (38, 50, 34) by means of an operating element (56) and continuously increasing it,

-closing the friction clutch (38), thereby matching the rotational speed of the second plate support (30) and the clutch body (36),

-moving the second plate support (30) in an axial direction (A) to engage a second form-locking element (54) of the form-locking clutch (50) into the first form-locking element (52),

-wherein, when a tooth-to-tooth position occurs between the two form-fitting elements (52, 54), the plate clutch (34) is closed by further increasing the axial force such that the friction torque of the closed plate clutch (34) is greater than the friction torque of the closed friction clutch (38), thereby causing a relative rotation between the second plate support (30) and the clutch body (36), until a tooth-to-space position is reached between the two form-fitting elements (52, 54), thereby reducing the friction torque of the plate clutch (34) such that the friction torque of the plate clutch is less than the friction torque of the closed friction clutch (38), thereby re-matching the rotational speeds of the second plate support (30) and the clutch body (36), and then the second form-fitting element (54) is engaged to the clutch body (36) by the axial force still applied by the operating element (56) In a first form-fitting element (52) of the form-fitting clutch (50), and the multi-plate clutch (34) is closed again by the action of an axial force of the actuating element (56).

2. Method according to claim 1, characterized in that the actuating element (56) is moved axially with increasing axial force, wherein, starting from an unactuated starting position, the shifting device (26) first assumes a synchronous position, then a form-locking position, and finally a closed position of the multi-plate clutch (34), wherein, in the unactuated starting position, the multi-plate clutch (34) is open and the second plate (32) of the second plate support (30) is not coupled in the circumferential direction with the first plate (28) and the first transmission component (25), and wherein, in the form-locking position, the second plate (32) of the second plate support (30) is coupled in the circumferential direction with the clutch body (36) via the form-locking clutch (50), and, in the closed position of the multi-plate clutch (34), the second plate (32) of the second plate carrier (30) is coupled in the circumferential direction via a friction connection with the first plate (28) of the first plate carrier and thereby with the first transmission component (25).

3. Switching device for a motor vehicle transmission, in particular for carrying out a method according to one of the preceding claims, having:

-a first transmission member (25) connectable with the second plate carrier (30) and a second transmission member (27) connected with the clutch body (36), wherein the transmission members (25, 27) are twistable relative to each other about a transmission axis (A),

-a friction clutch (38) comprising a friction ring (40) which is connected in a rotationally fixed and axially displaceable manner in the circumferential direction to the second plate carrier (30) or the clutch body (36) and which has a conical friction surface (42) and a counter-friction surface (44) which interacts in a rotationally fixed manner with the clutch body (36) or the second plate carrier (30) and can be brought into abutment with the friction ring (40) by displacing the friction ring (40),

-a plate clutch (34) comprising a plurality of second plates (32) arranged on the second plate carrier (30) and connected to each other in a circumferential direction relatively non-rotatable and axially movable manner, and a plurality of first plates (28) coupled to the first transmission component (25) and connected to each other in a circumferential direction relatively non-rotatable and axially movable manner, wherein the first plates (28) and the second plates (32) are arranged one after the other in an axial direction alternately, and

-a form-locking clutch (50) comprising a first form-locking element (52) arranged on the clutch body (36) and a second form-locking element (54) arranged on the second plate support (30), wherein the first form-locking element (52) and the second form-locking element (54) are axially engaged with each other and are thus able to enter a form-locking connection,

-and an operating element (56) which exerts an axial force on the second plate bearing (30) in order to close the friction clutch (38), the form-fitting clutch (50) and the plate clutch (34), wherein the operating element (56) acts on the second plate bearing (30) on a force transmission path which is formed solely by a rigid component.

4. A transformation device according to claim 3, characterized in that the first transmission member (25) or the second transmission member (27) constitutes a transmission shaft (24) rotatable about the transmission axis (a) or is firmly connected with such a transmission shaft (24), and the other transmission member (27, 25) constitutes a transmission housing (16) which is not rotatable relative to one another or is firmly connected with such a transmission housing (16) or constitutes a further transmission shaft (24) rotatable about the transmission axis (a) or is firmly connected with such a further transmission shaft (24).

5. The transformation apparatus according to any one of claims 3 and 4, characterized in that the second form-locking element (54) is integrally formed with the second sheet support (30).

6. The changeover device according to any one of claims 3 to 5, characterized in that an annular spring (46) is arranged between the second plate support (30) and the friction ring (40), which annular spring acts on the second plate support (30) in the direction of the actuating element (56) and which is prestressed when the actuating element (56) is moved axially, in particular in that the annular spring (46) is the only spring element present between the second plate support (30) and the clutch body (36).

7. A transformation device according to claim 6, characterized in that the annular spring is located in the force flow between the operating element (56) and the friction ring (40).

8. Switching device as in any of claims 3 to 7, characterized in that the mating friction surface (44) is configured directly on the clutch body (36).

9. The changeover arrangement according to any one of claims 3 to 8, characterized in that the friction ring (40) is located radially inside the second plate support (30) and is arranged on the second plate support (30) or the clutch body (36) so as to be axially displaceable, but not so as to be relatively rotatable in the circumferential direction.

10. The transformation device according to any one of claims 3 to 8, wherein the friction ring (40) is located radially outside and surrounds the second sheet support (30), in particular one of the second sheets (32) has a friction cone surface cooperating with the friction ring (40).

11. The changeover device according to any one of claims 3 to 10, characterized in that the second sheet support (30) has a central region extending axially with respect thereto, which central region has a circumferential recess in cross section, on both sides of which recess an annular spring is arranged on the radially inner side.

Images