Device and method for controlling a clutch unit

Abstract

A device (1) for controlling a clutch unit (2, 2') has a piston (4, 4'), which is displaceable in the axial direction (x), for acting upon an element (3, 3') of the clutch unit (2, 2') with a first force (F1) by means of a pressure (p) acting on the piston (4, 4'), and an actuating element (9), which is displaceable in the axial direction (x), acts at least indirectly with a second force (F2) on the element (3, 3') of the clutch unit (2, 2') and is provided to control the pressure (p) acting on the piston (4, 4') and in this way the first force (F1), wherein an overall force (F3) acting on the element (3, 3') of the clutch unit (2, 2') is produced by the first force (F1) and the second force (F2).

Description

[0001] Device and method for controlling a clutch device

[0002] This application claims priority from German patent application No. 10 2022 130 689.5, the contents of which are incorporated herein by reference.

[0003] The invention relates to a device for controlling a clutch device, comprising a piston which is displaceable in the axial direction for applying a first force to an element of the clutch device by means of a pressure acting on the piston. Furthermore, the invention relates to a method for controlling a clutch device, wherein an element of the clutch device is subjected to a first force by means of a pressure acting on the piston by means of a piston which is displaceable in the axial direction.

[0004] Electrified vehicles usually have a central drive with an electric motor and a differential, or independent wheel drives, where each electric drive motor is connected to a wheel via a gearbox and a sideshaft. Electrified vehicles with more than one gear typically contain slipping clutches in the transmission. If the clutch is actuated by a hydraulic actuator that rotates with the clutch, leakage and friction occur at a hydraulic rotary joint or rotary union that connects the rotating actuator to a non-rotating pump, typically attached to the gearbox housing. If the clutch is actuated via engagement or release bearings, energy losses occur due to bearing friction, particularly in high-speed electric drives.

[0005] For reasons of comfort and driving safety, gear shifts should be as seamless as possible. In general drive technology, appropriate powershift transmissions are also required for certain applications. Powershifts with overlapping shifts require significant actuator complexity, associated with corresponding energy losses. If multiple clutches are installed, a separate actuator is typically provided for each one.

[0006] DE 10 2021 118 203 B3 describes a system for coupling a shaft with a coupling partner, which system has a centrifugal actuator with a centrifugal cylinder and a centrifugal piston displaceably received therein, a coupling device with two coupling members, one of which is connected to the shaft and the other to the coupling partner, and a fluid channel connecting the centrifugal actuator to the coupling device.

[0007] EP 0 738 836B 1 describes a method for controlling the speed of a friction clutch in a drive unit comprising a prime mover. The friction clutch comprises at least two clutch parts that can be pressed against one another for the purpose of transmitting torque, namely a first clutch part that is at least indirectly coupled to the prime mover, and a second clutch part that can be coupled to the prime mover via the first clutch part. The contact force required for torque transmission between the clutch parts can be applied hydraulically or, at least once the prime mover reaches idle speed, automatically by the rotational pressure of a rotating ring of hydraulic fluid.To adjust the speed in the starting range of the drive unit or during creeping travel, the pressure required to apply the contact force is varied by active external influence by changing the filling level of the rotating ring of hydraulic fluid.

[0008] It is an object of the present invention to provide a device and a method for controlling a coupling device with which energy efficiency and driving safety are improved, in particular in hybrid and electric vehicles as well as rail and ship drives.

[0009] According to the invention, this object is achieved by the features mentioned in claim 1.

[0010] The device according to the invention for controlling a clutch device accordingly comprises an axially displaceable piston for applying a first force to an element of the clutch device by means of a pressure acting on the piston. Furthermore, an axially displaceable actuating element is provided, which acts at least indirectly with a second force on the element of the clutch device and can be used to control the pressure acting on the piston.

[0011] By using an actuating element that applies a second force to the clutch element and is simultaneously able to control the pressure acting on the piston, it is possible to apply the force required to hold the clutch element in place for a short time, rather than permanently as was previously the case. This means that the clutch element can be held in place permanently by applying a force only for a short time, which not only results in considerable energy savings, but also significantly reduces the loads acting on the individual components. A clutch that is normally open when not actuated can thus be kept permanently closed, while a clutch that is normally closed when not actuated can be kept permanently open.

[0012] The first force and the second force result in a total force acting on the element of the coupling device.

[0013] The actuating element preferably controls the pressure acting on the piston by influencing an inlet and / or outlet of a pressure medium. This can be achieved, for example, by a cross-sectional change in the inlet and / or outlet or an inlet bore and / or outlet bore influenced by the actuating element. The actuating element can also preferably control the pressure acting on the piston by influencing an effective volume of the pressure medium or a filling or a filling level. In a very advantageous development of the invention, it can be provided that the actuating element acts on the element of the coupling device with the second force via the piston. In this way, the force acting on the element of the coupling device only needs to be transmitted via the piston, whereby additional components can be dispensed with.

[0014] A further advantageous embodiment of the invention can consist in that the pressure acting on the piston is generated by means of centrifugal force by a pressure medium rotating in a pressure chamber adjacent to the piston. Generating the pressure acting on the piston by means of centrifugal force enables the use of an already existing pressure medium rotating in a pressure chamber, which also eliminates the need for additional components and simplifies the device according to the invention. The rotation of the pressure medium resulting from the rotation of the shaft leads to a centrifugal force acting on the pressure medium, which in turn acts on the piston. The actuating element can be relieved of an actuating force by a rotational pressure resulting from centrifugal forces acting on the pressure medium, wherein the actuating element is simultaneously able to influence the rotational pressure.By relieving the load on the actuating element in this way, energy losses are advantageously reduced, especially at higher speeds.

[0015] In this context, a further advantageous embodiment of the invention can consist in that a reservoir for the pressure medium is formed by a hollow space in a rotatable shaft, wherein the reservoir for the pressure medium is connected to the pressure chamber via at least one inlet bore provided on the outer surface of the shaft in such a way that the pressure medium is supplied to the pressure chamber by centrifugal force. This embodiment uses existing components, wherein only one bore, preferably at least one inlet bore, is provided in a rotatable shaft. Due to the centrifugal force, the pressure medium rotating in the shaft passes through the at least one inlet bore into the pressure chamber to generate a pressure there that acts on the piston and thus displaces it in the axial direction towards the element of the coupling device.

[0016] An embodiment of the invention that is particularly relevant in practice arises when the actuating element is designed as an engagement or release bearing arranged on a rotatable shaft and displaceable in the axial direction by means of an actuator. The engagement or release bearing couples the non-rotating actuator with the rotatable element of the clutch device, transmits the actuator force and acts at least indirectly with the second force on the element of the clutch device. Rolling bearings, in particular needle bearings or deep groove ball bearings in axial or radial design, hydrodynamic or hydrostatic plain bearings, magnetic bearings, air bearings or a combination of these bearing types can be used as engagement or release bearings. The engagement or release bearing can also take on the function of the actuator, e.g. in the case of a magnetic or air bearing.

[0017] Furthermore, the piston can be provided with at least one drain hole that can be closed by the actuating element. In this solution, the current position of the actuating element influences the effective cross-section of at least one drain hole and thus the volume flow of the pressure medium through the drain hole. Thus, the pressure acting on the piston can be controlled by the actuating element in a structurally simple manner, for example, according to the principle of a seat valve.

[0018] In order to be able to control the volume flow of the pressure medium, it can further be provided that a device for changing the cross-section of the at least one drain hole is arranged within the same.

[0019] Furthermore, the effective cross-sections of at least one inlet bore and / or the at least one outlet bore can also be influenced by an actuator position, the actuator force, a piston position, the first force resulting from the pressure acting on the piston, the position of the actuating element, the second force resulting from the action of the actuating element, a current rotational speed, a current rotational pressure, a current volume of the pressure medium currently contained in the pressure chamber, a current temperature, and / or a current total force on the element of the clutch device. The total force can be composed of the first force resulting from the pressure acting on the piston and the second force resulting from the action of the actuating element.

[0020] In a very advantageous embodiment of the invention, it can be provided that the element of the clutch device is designed as a friction element. The friction surfaces of this friction element can be disc-shaped, as in frictional single-surface clutches, single-disk clutches or multi-disk clutches or multi-plate clutches, conical as in cone clutches, or cylindrical as in cylindrical or shoe clutches. The friction surfaces can be operated dry, oiled or wet. The power can be transmitted via friction, with the total force acting on the element of the clutch device representing or generating the normal force or contact force required for friction. This means that the total force, which can be made up of the first force due to the pressure acting on the piston and the second force due to the effect of the actuating element, generates a frictional connection between the friction surfaces of the friction element.

[0021] Claim 10 specifies a method for controlling a clutch device.

[0022] In the method according to the invention, an element of the clutch device is subjected to a first force by means of an axially displaceable piston by means of a pressure acting on the piston. Furthermore, an axially displaceable actuating element acts at least indirectly with a second force on the element of the clutch device and is provided to control the pressure acting on the piston.

[0023] Using the method according to the invention, a clutch device can be operated in a simple and energy-efficient manner. In a very advantageous development of the invention, the actuating element can act on the clutch device element with the second force via the piston. This eliminates the need for additional components because the force acting on the clutch device element is transmitted solely via the piston.

[0024] A further advantageous embodiment of the method results when the pressure acting on the piston is generated by centrifugal force from a rotating pressure medium, wherein the pressure medium is fed to a pressure chamber adjacent to the piston by centrifugal force from a cavity of a rotating shaft. In this way, an already existing pressure medium rotating in a pressure chamber is used as auxiliary energy by utilizing centrifugal force, which eliminates the need for additional components. The actuating element is relieved of an actuating force by a rotational pressure resulting from centrifugal forces acting on the pressure medium, thereby reducing energy losses, particularly at higher speeds.

[0025] If, in a further advantageous embodiment, a dynamic mathematical model is stored in a control device which calculates and / or estimates and / or observes the volume of the pressure medium currently contained in the pressure chamber and / or the pressure and / or the first force, the actuator can be controlled in an improved manner using this information.

[0026] Furthermore, if the clutch device is part of a dual-clutch transmission, it can be provided that the actuating element, which is displaceable in the axial direction, acts at least indirectly with a further force on an element of a second clutch device during an overlap shift of the dual-clutch transmission. In this way, so-called overlap shifts can be carried out very simply and in an energy-saving manner. For example, in the case of two clutch devices that are open in the unactuated state (“normally open”), the actuating element or actuator specifies the temporal behavior of a second closing clutch device, while the temporal profile of the rotational pressure or the pressure medium contained in the piston chamber, influenced by the inlet bores and / or the outlet bores, specifies the temporal behavior of a first, opening clutch device in the dual-clutch transmission.In this way, powershift operations with overlapping shifts can be implemented cost-effectively using a single actuating element, e.g., an engagement or release bearing, or a single actuator. With only one actuating element, energy losses are reduced, and simultaneous, complete engagement of both clutch devices, which could lead to a safety-critical, faulty locking of the transmission, is reliably eliminated.

[0027] A further advantageous embodiment of the method according to the invention, which is also particularly suitable for an overlap shift in a dual-clutch transmission, can consist in that the actuating element which is displaceable in the axial direction specifies the temporal closing process of the element of the second clutch device and at the same time the piston specifies the temporal opening process of the element of the first clutch device by specifying the temporal course of the pressure acting on the piston and in this way the first force and / or the axial position of the piston by throttling the volume flow of the pressure medium via at least one inlet bore and / or at least one outlet bore.

[0028] Preferably, the temporal opening process of the element of the first, opening clutch device can be calculated and / or estimated and / or observed with the aid of a dynamic mathematical model in the control device based on measured variables and, based thereon, the temporal closing process of the element of the second, closing clutch device can be specified.

[0029] The device according to the invention and the method according to the invention can be used in many ways, in particular in motor vehicles with electric drive, but also, for example, in hybrid vehicles, ship drives, railway drives and other drive systems.

[0030] In the following, embodiments of the invention are shown in principle with reference to the drawing.

[0031] It shows:

[0032] Fig. 1 shows a device according to the invention for controlling a clutch device in a first state;

[0033] Fig. 2 shows the device from Fig. 1 in a second state;

[0034] Fig. 3 is a further illustration of the device from Fig. 1;

[0035] Fig. 4 shows a first further development of the device according to the invention;

[0036] Fig. 5 shows a second development of the device according to the invention;

[0037] Fig. 6 shows a third development of the device according to the invention; and

[0038] Fig. 7 is a diagram illustrating a method that can be carried out with the embodiment according to Fig. 6.

[0039] Fig. 1 shows a device 1 for controlling a clutch device 2, which is shown very schematically in Fig. 1. The clutch device 2 is part of a transmission, which in turn can be part of, for example, an electric vehicle. However, it is also possible to use the clutch device 2 in transmissions of hybrid vehicles, ship propulsion systems, rail propulsion systems, and other drive systems. The transmission can be driven by an electric motor, an internal combustion engine, a hydraulic and / or a pneumatic machine. The axial direction designated by "x" is the longitudinal direction of a rotatable, rotationally symmetrical shaft 5, which simultaneously serves as the drive shaft or transmission input shaft of the clutch device.

[0040] 2. The rotation of the shaft 5 is transmitted by the clutch device 2 to a drive gear 7 and a driven gear 6 meshing with the latter.

[0041] Shaft 5 can be driven by an electric motor (not shown) without an intermediate pre-stage. Eliminating a reduction pre-stage reduces gearing losses. Clutch device 2 can then be designed for lower torques, but it should be suitable for the maximum speeds of the electric motor, typically over 15,000 rpm.

[0042] The clutch device 2 can, for example, be designed as a wet-running multi-plate clutch with steel and friction plates constituting one or more elements 3 of the clutch device 2. The inner plates are guided and driven by a toothing (not further specified) on the shaft 5. An inner plate carrier as a separate component connected to the shaft 5 would also be possible. The outer plates are guided in a toothing of an outer plate carrier 2a of the clutch device 2, which is integrally connected to the drive gear 7. The drive gear 7 is mounted on the shaft 5 via bearing elements 8 designed as needle bearings and meshes with the output gear 6, which drives the drive wheels of the vehicle via a differential gear and side shafts in a manner not shown.

[0043] In the "open" state of the clutch device 2 shown in Fig. 1, the outer and inner plates are separated from each other by means of expanding springs (not shown). A predefined clearance can be set to minimize drag torque caused by shear forces within a transmission oil located between the plates, or generally a pressure medium, at a differential speed between the outer and inner plates. No significant torque transmission occurs, the outer and inner plates are not in direct frictional contact, and the drive gear 7 can rotate freely against the shaft 5.

[0044] As described above, several elements 3 of the clutch device 2 are shown, which are designed as clutch plates or outer and inner plates. In the state of Fig. 1, the elements

[0045] 3 of the coupling device 2 are spaced apart from one another. This state of the coupling device 2 is, as already mentioned, referred to as "open." In contrast, the elements 3 of the coupling device 2 in the state shown in Fig. 2 are not spaced apart, but rather rest against one another. This state of the coupling device 2 is referred to as "closed." As described below, the device 1 serves to move the coupling device 2 from its open to its closed state and vice versa.

[0046] For this purpose, the device 1 has a rotationally symmetrical piston 4, which is displaceable in the axial direction designated by "x," and by which the element 3 is at least indirectly subjected to a first force F1, designated in Fig. 3, in order to ultimately move the clutch device 2 from its open to its closed state. A disk pack formed from several disks can also be considered the element 3 of the clutch device 2 acted upon by the displaceable piston 4. The first force F1 is generated by a pressure p acting on the piston 4, designated in Figures 2 and 3, whereby the piston 4 is moved to the left in the illustration of Figures 1 and 2. To return the clutch device 2 to the open or rest position shown in Fig. 1, one or more springs or expanding springs (not shown) can be provided, which move the piston 4 to the right in the illustration of the figures.

[0047] The device 1 further comprises an actuating element 9, which is also displaceable in the axial direction x and acts at least indirectly on the element 3 of the coupling device 2 with a second force F2, also indicated in Fig. 3. The coupling device 2 or the element 3 of the coupling device 2 can therefore be acted upon both by the piston 4 with the first force F1 and by the actuating element 9 with the second force F2. As described in more detail below, the actuating element 9 is further provided to control the pressure p acting on the piston 4. The actuating element 9 acts on the element 3 of the coupling device 2 with the second force F2 via the piston 4.

[0048] In the general case, the actuating element 9 connects an electromechanical or electromagnetic (e.g. electric motor, geared motor, solenoid or plunger coil), piezoelectric, pneumatic or hydraulic actuator that is rotatable with the shaft 5 or that is not rotatable, at least indirectly, to the element 3 of the coupling device 2.

[0049] The actuating element 9 is in the present case designed as an engagement and release bearing arranged on the rotatable shaft 5 and displaceable in the axial direction x by means of an electromechanical, pneumatic or hydraulic actuator (not shown). The actuating element 9 is displaceable independently of the piston 4. The clutch device 2 is therefore actuated with the aid of the actuator, which does not rotate with the shaft 5 or the clutch device 2. This eliminates, for example, leakage and friction of an otherwise necessary hydraulic rotary transformer or a hydraulic rotary feedthrough. The actuating element 9 is therefore displaced by the actuator in the axial direction x and applies the second force or the axial actuator force F2. Together with the first force or the piston force F1, the total force or axial force or normal force F3 is generated on the element 3 orthe plate pack of the clutch device 2, consisting of the outer and inner plates, as shown in Fig. 3.

[0050] The actuating element 9, which in the present case acts as an engagement bearing, has an inner ring 9a that rotates with the shaft 5, while an outer ring 9b of the actuating element 9 is connected to the actuator and does not rotate. For the sake of simplicity, the engagement bearing is shown in the figures as a deep groove ball bearing, although any other bearing design is also possible, in particular an axial deep groove ball bearing. In the exemplary embodiment, the axial actuator force F2 is absorbed by a bearing 10 of the shaft 5, which guides the shaft 5 and, for example, absorbs the tooth forces of the output gear 6. Additional axial forces acting, for example as a result of helical gearing of the output gear 6, are not taken into account in Fig. 3 for the sake of simplicity. It is also possible to use an additional bearing that supports the axial actuator force F2. In the engagement bearing as well as the bearing 10 orThe additional bearing generates frictional torques due to the axial actuator force F2, which lead to efficiency losses. The goal is therefore to reduce the axial actuator force F2 and, to compensate, increase the piston force F1 or the pressure p acting on piston 4 in order to continue to generate the total force or normal force F3 required during operation on element 3 or the disk pack of clutch device 2.

[0051] The pressure p acting on the piston 4 is in the present case generated by centrifugal force from a pressure medium rotating in a pressure chamber 11 adjacent to the piston 4. The pressure chamber 11 is connected to a reservoir 13 for the pressure medium via at least one inlet bore 12 provided on a circumferential surface of the shaft 5. The reservoir 13 for the pressure medium is formed in the present case by a rotationally symmetrical cavity of the rotatable shaft 5. The rotation of the shaft 5 conveys the pressure medium to the peripheral wall of the cavity or reservoir 13 and from there reaches the pressure chamber 11 via the at least one inlet bore 12. There, the pressure medium generates the pressure p described above, which generates the first force or piston force F1 for acting on the element 3 of the clutch device 2.

[0052] Preferably, the cross-section of the cavity of the rotatable shaft 5 is reduced at the open end in order to prevent the pressure medium from flowing away opposite to the axial direction or longitudinal direction designated by "x", as shown in Fig. 6.

[0053] The pressure medium can be transmission oil, which is supplied to the cavity or reservoir 13, for example, via an oil pump (not shown) or by collecting transmission oil swirling around inside the transmission and feeding it through channels. Due to the centrifugal force when the shaft 5 rotates, the transmission oil is also guided via additional bores 14 for lubrication or cooling to the bearing elements 8 of the drive gear 7 and between the outer and inner plates of the clutch device 2, i.e., the elements 3 thereof subjected to the first force or piston force F1 and the second force or axial actuator force F2.

[0054] As described above, Fig. 2 shows the device 1 from Fig. 1 in the closed state of the clutch device 2. The actuator (not shown) displaces the actuating element 9, designed as an engagement bearing, in the axial direction to the left. The actuator or the actuating element 9 changes its axial position x from x = 0 with the clutch device 2 open according to Fig. 1 to x = x according to Fig. 2, whereby the element 3 of the clutch device 2 or the disk pack is pressed together and frictional contact is created between the outer and inner disks. The total force or normal force F3 is generated at the element 3 of the clutch device 2 or at the disk pack. Friction then occurs in the friction contacts, which leads to the maximum transmission of a torque MKI of the closed clutch device 2 shown in Fig. 2: M K1 = n ■ / j. ■ r m ■ F3 (1)

[0055] Where n denotes the number of friction surfaces, / z the friction coefficient of the friction pairing of outer and inner plates and r m the average friction radius.

[0056] Without further measures, it would be disadvantageous that both the actuator and the actuating element 9 would have to maintain the total force or normal force F3 on the plate pack when the clutch device 2 is closed. A speed- and load-dependent frictional torque arises in the rotating actuating element 9. Due to the high maximum speeds of the electric machine, typically over 15,000 rpm, and thus of the shaft 5, a high power loss occurs, with negative effects on energy efficiency and effectiveness. In continuous operation, the resulting power loss may not be able to be dissipated from the actuating element 9, resulting in damage. The bearing 10 of the shaft 5 is also subjected to additional load. The device 1 described here with the movable piston 4 for applying the first force orPiston force F1 by means of the pressure p acting on the piston 4 and the actuating element 9, which is displaceable in the axial direction x and acts at least indirectly with the second force or axial actuator force F2 on the element 3 of the clutch device 2 and is intended to control the pressure p acting on the piston 4, provides a remedy here.

[0057] This also applies to a method for controlling the clutch device 2, in which the element 3 of the clutch device 2 is subjected to the first force or piston force F1 by means of the piston 4, which is displaceable in the axial direction x, by means of the pressure p acting on the piston 4, in which, furthermore, the actuating element 9, which is displaceable in the axial direction x, acts at least indirectly on the element 3 of the clutch device 2 with the second force or axial actuator force F2, and in which the actuating element 9 is provided to control the pressure p acting on the piston 4. In this case, the actuating element 9 acts on the element 3 of the clutch device 2 via the piston 4 with the second force or axial actuator force F2.

[0058] As already described with reference to the device 1, the pressure p acting on the piston 4 is generated by means of centrifugal force by the rotating pressure medium, wherein the pressure medium is supplied to the pressure chamber 11 adjacent to the piston 4 by means of centrifugal force from the cavity of the rotatable shaft 5.

[0059] As described, the actuating element 9 acts on the element 3 of the clutch device 2, i.e. on the plate pack, via the piston 4, which is axially displaceable on the shaft 5. The piston 4, together with the shaft 5 or a flange 15 integrally connected to the shaft 5, forms the piston chamber or pressure chamber 11. The flange 15 accommodates a piston seal 16, which enables axial displacement of the piston 4, but seals the pressure chamber 11. As described, the shaft 5 has at least one inlet bore 12 from the accumulator 13 in the interior of the shaft 5 to the pressure chamber 11, whereby the pressure medium reaches the pressure chamber 11 via the at least one inlet bore 12 as a result of the centrifugal force when the shaft 5 rotates. A further piston seal (not shown) between the shaft 5 and the inner region of the axially displaceable, rotationally symmetrical piston 4 near the at least one inlet bore 12 is also possible.An anti-rotation device (not shown) can prevent rotation of the axially displaceable, rotationally symmetrical piston 4 relative to the shaft 5.

[0060] The piston 4 also has at least one drain bore 17, which, as can be seen in Figures 1 and 2, can be opened and closed by means of the actuating element 9. The pressure medium supplied via the at least one inlet bore 12 can completely drain away again via the at least one drain bore 17 when the coupling device 2 is open. The cross-sections and number of inlet and drain bores can be designed according to requirements.

[0061] In the state illustrated in Figures 2 and 3, the actuating element 9 closes the at least one drain hole 17 with its rotating inner ring 9a or a flange coupled thereto when the clutch device is closed. The inner ring 9a or the flange can contain sealing elements, for example made of elastomer material, for this purpose. The pressure medium then collects in the pressure chamber 11, forming a fluid ring due to the centrifugal forces when the shaft 5 rotates. The resulting rotational pressure p acts on the piston 4 and generates the piston force F1. The total force or normal force F3 acting on the element 3 of the clutch device 2 or the disk pack is then the sum of the first force or piston force F1 due to the rotational pressure p and the second force or axial actuator force F2:

[0062] F3 = F1 + F2 (2)

[0063] The rotational pressure p or the piston force F1 relieves the load on the actuating element 9 or the actuator. This means that as the piston force F1 increases, the axial actuator force F2 can be reduced, while the total force or normal force F3 remains constant.

[0064] Depending on the design and speed of the shaft 5 or the resulting centrifugal force, the total force or normal force F3 can be applied entirely by the piston force F1, or the piston force F1 and the axial actuator force F2 act together. Advantageously, the device 1 designed as described above reduces the axial actuator force F2 or the axial force of the actuating element 9. This can be done based on the measured or estimated piston force F1 or the volume of the pressure medium contained in the pressure chamber 11 or the current speed of the shaft 5 or the rotational pressure p. Particularly at high speeds, at which high power loss would otherwise occur in the actuating element 9, the axial actuator force F2 or the axial force of the actuating element 9 and thus also the power loss can be greatly reduced.In addition, the bearing 10 of the shaft 5, which supports the axial actuator force F2, is also relieved of load and its power loss is reduced. In order to generate a sufficiently high rotational pressure p even at lower speeds, the outer diameter of the piston 4 can be selected to be larger than the outer diameter of the outer plate carrier 2a of the clutch device 2. Alternatively or additionally, in a manner not shown, several pistons can be mounted axially next to one another and thus connected in series, the piston forces of which then add up to the total piston force F1. In this case, each of the pistons can have its own inlet and outlet bores. A piston with several separate pressure chambers is also possible, whereby the individual forces exerted by the piston chambers add up to the total piston force F1.

[0065] Elasticity is usually present within the disk pack, for example, in sinusoidal disks or additional spring elements acting in the axial direction. In this case, the current axial position of piston 4 and the total force or normal force F3 acting on the disk pack are related via a spring characteristic curve. Device 1 also offers advantages in this case. With sufficient rotational speed of shaft 5 or sufficient centrifugal force, a force equilibrium will be established on piston 4 such that the total force or normal force F3 acting on the disk pack results almost entirely from the piston force F1 due to the rotational pressure p:

[0066] F3 = F1 (3)

[0067] During stationary operation, the piston 4 then lifts with the at least one outlet bore 17 from the actuating element 9 or the sealing element attached thereto until the volume flow of the pressure medium via the at least one outlet bore 17 corresponds to the volume flow of the pressure medium via the at least one inlet bore 12 and the volume of the pressure medium in the pressure chamber 11 remains constant. At a constant speed of the shaft 5, the rotational pressure p or the piston force F1 also remain constant. Then only a small axial actuator force F2 is transmitted from the actuating element 9 to the piston 4 and the actuating element 9 is almost completely relieved of load. In this context, the device 1 or the method carried out with the same forms a hydraulic position control of the piston 4, wherein the axial position of the piston 4 is specified as the actual value from the axial position x of the actuating element 9 or the actuator as the setpoint.Intermediate positions can also be set which are neither associated with a fully open nor a fully closed clutch device 2 in order to set a reduced total force or normal force F3. According to equation (1), a reduced slip torque MKI results, at which the clutch device 2 changes from the non-slipping state, i.e. a differential speed equal to zero between the outer and inner plates, to the slipping state, i.e. to a differential speed not equal to zero. This can be used, for example, to reduce external shocks on the drive system by briefly slipping. Typically, the slip torque MKI is selected to be somewhat higher than the drive torque currently acting on shaft 5 from the electric motor.During the closing process of the clutch device 2, the piston force F1 does not arise immediately, but only after a delay due to the filling of the pressure chamber 11 with the pressure medium and the resulting delayed build-up of the rotational pressure p. The filling process of the pressure chamber 11 with the pressure medium begins when the at least one drain bore 17 is closed by the actuating element 9. Thus, the temporal build-up of the total force or normal force F3 on the plate pack of the clutch device 2 can initially be specified very precisely by the axial actuator force F2 or the axial actuator position x. The temporal progression can, for example, be adapted to the current operating state of the vehicle. This is particularly advantageous during powershift processes in dual-clutch transmissions with overlapping engagement of two clutch devices 2.

[0068] Furthermore, it can be provided that the current speed of the shaft 5, the current temperature and thus the viscosity of the pressure medium as well as the current axial actuator position x and / or the current axial position of the actuating element 9 and / or the current axial position of the piston 4 or their temporal profiles are determined and made available to a control device, such as a transmission control. These variables influence the volume flow of the pressure medium via the at least one drain bore 17 and / or the volume flow of the pressure medium via the at least one inlet bore 12 and thus the filling of the pressure chamber 11 or the volume of the pressure medium contained therein and thus the rotational pressure p or the piston force F1. The control device can determine the current piston force F1 from these variables.If elasticity is present in the plate pack, the current axial actuator position x and / or the current axial position of the actuating element 9 and / or the current axial position of the piston 4 can be recorded in order to determine the total force or normal force F3 on the plate pack using a spring characteristic curve. By recording the current axial actuator force F2, the current piston force F1 or the current rotational pressure p can then be determined. This can be used to determine variables that influence the rotational pressure p and / or for error detection. One variable that influences the rotational pressure is, for example, the volume of the pressure medium currently contained in the pressure chamber. From the torque currently to be transmitted by the plate pack of the clutch device 2, a required total force or normal force F3 can be determined in order to suitably adjust the frictional engagement in the plate pack.Together with the current piston force F1 determined as described above, a required axial actuator force F2 can be determined and set. The torque currently to be transmitted by the disk pack can be determined, for example, based on the current torque of a drive motor. By adapting the axial actuator force F2 to the torque currently to be transmitted by the disk pack, taking into account the current piston force F1, losses, for example in an engagement or release bearing or in the actuator, are further minimized. A dynamic mathematical model is preferably stored in a control device, which calculates, estimates, or observes the volume of the pressure medium currently contained in the pressure chamber 11 and / or the rotational pressure p and / or the first force or piston force F1. This information can be used to improve the control of the actuator.In addition, it is proposed to influence the cross sections of the at least one inlet bore 12 and / or the at least one outlet bore 17 and thus the volume flows of the pressure medium via the at least one inlet bore 12 and / or the at least one outlet bore 17 depending on the current axial actuator position x, the current axial position of the actuating element 9, the current axial position of the piston 4, the current actuator force F2 or the second force due to the effect of the actuating element, the piston force F1, the current speed of the shaft 5, the current rotational pressure p, the pressure medium volume currently contained in the pressure chamber 11, the current temperature and thus the viscosity of the pressure medium and / or the current total force or normal force F3 on the plate pack. This can be achieved, for example, by the at least one inlet bore 12 being actuated at a total force orNormal force F3 equal to zero, corresponding to an open coupling device 2 according to Fig. 1, is closed, while at least one drain bore 17 is opened. This prevents the pressure medium from flowing through the pressure chamber 11, which minimizes efficiency losses due to flow losses.

[0069] Likewise, the at least one inlet bore 12 can be closed when the second clutch device 2' is open according to the embodiment of Fig. 6 in the illustrated axial rest position of the piston 4'. Then, no volume flow occurs via the pressure chamber 11 and associated flow losses are eliminated. If the total force or normal force F3 is too high, the cross-sections of the at least one inlet bore 12 can be reduced, while the cross-sections of the at least one outlet bore 17 can be increased in order to reduce the volume of the pressure medium contained in the pressure chamber 11 and the rotational pressure p. This can be used, for example, to avoid excessive surface pressures on the friction linings of the plates. Pressure relief valves that limit the rotational pressure p are also possible.Since the temporal course of the build-up and reduction of the rotational pressure p depends strongly on the current speed of the shaft 5, a speed-dependent influencing of the cross sections of the at least one inlet bore 12 and / or the at least one outlet bore 17 is also useful, for example in order to adjust the temporal behavior of the volume flows of the pressure medium via the at least one inlet bore 12 and / or the at least one outlet bore 17 and thus the build-up and reduction of the rotational pressure p or the axial position of the piston 4 at different speeds.It is also possible to take into account the current temperature and thus the viscosity of the pressure medium, for example by changing the effective cross sections by means of a thermobimetal in order to adapt the temporal behavior at different temperatures. A dependence of the effective cross sections of the at least one drain hole 17 on the pressure medium volume currently contained in the pressure chamber 11 can be achieved, for example, with the aid of additional overflow holes.

[0070] Fig. 4 shows a possibility for influencing the volume flow of the pressure medium via the at least one drain hole 17, depending on the current speed of the shaft 5, by means of a device

[0071] 18 to change the cross-section of the same. Within the drain hole 17, a slide

[0072] 19 is provided, which is pressed by a spring element 20 in the direction of the pressure chamber 11. Speed-dependent centrifugal forces act on the slide 19 against the force of the spring element 20 and change the position of the slide 19, resulting in a change in the cross-section of the at least one drain bore 17. In this case, the slide 19 is designed as a hollow cylinder, the cylinder walls of which have several bores distributed radially around the circumference.

[0073] Fig. 5 shows a possibility for influencing the volume flow of the pressure medium via the at least one drain bore 17 depending on the current total force or normal force F3 on the plate pack of the clutch device 2. The piston 4 does not act directly on the clutch plates or elements 3 of the clutch device 2, but transmits the total force or normal force F3 via a slide 21, which is loaded by means of a spring element 22, for example designed as a helical spring or disc spring. If the total force or normal force F3 changes, the position of the slide 21 and thus the cross-section of the drain bore 17 changes. In the present case, the slide 21 is partly designed as a hollow cylinder, the cylinder walls of which have a plurality of bores distributed around the circumference in the radial direction.Sealing elements 23 assigned to the slide 21 ensure the seal between the piston 4 and the slide 21, but enable a change in the position of the slide 21 within the piston 4. Similarly, spring-loaded slides can also act from the piston 4 to the actuating element 9 and influence the volume flow of the pressure medium via inlet or outlet bores depending on the current axial actuator force F2.

[0074] In addition, it is proposed to influence the cross section of at least one further bore 14 for lubricating or cooling the bearing elements 8 of the drive gear 7 and / or the outer and inner plates of the clutch device 2 and thus the volume flows of the pressure medium via the at least one further bore 14 depending on the current axial actuator position x, the current axial position of the actuating element 9, the current axial position of the piston 4, the current actuator force F2 or the second force due to the effect of the actuating element, the piston force F1, the current speed of the shaft 5, the current rotational pressure p, the pressure medium volume currently contained in the pressure chamber 11, the current temperature and thus the viscosity of the pressure medium and / or the current total force or normal force F3 on the plate pack.This reduces the flow of the pressure medium through the bearing elements 8 and / or through the spaces between the outer and inner plates of the clutch device 2. Efficiency losses due to viscous friction can thus be minimized when the bearing elements 8 and / or the clutch device 2 are subjected to low loads, particularly when the clutch device 2 is open as shown in Fig. 1. For this purpose, the options for influencing the volume flows of the pressure medium shown in Fig. 4 and Fig. 5 can be used.

[0075] In a further development of the device 1, the actuator according to Fig. 6 can actuate the two clutch devices 2 and 2' of a dual-clutch transmission. With an axial position of the actuating element 9 or an axial actuator position x = x1, the first clutch device 2 is fully closed and the second clutch device 2' is fully open, whereas with an axial actuator position x = x2 (with negative x2), the second clutch device 2' is fully closed and the first clutch device 2 is fully open. Each of the two drive gears 7 and 7' forms the ratio of a gear with the associated output gear 6 or 6'. The two output gears 6 and 6' are located on a common output shaft (not shown), which drives the drive wheels of the vehicle via a differential gear and side shafts in a manner not shown.

[0076] First gear is engaged by closing the first clutch device 2 while the second clutch device 2' is open. Second gear is engaged by closing the second clutch device 2' while the first clutch device 2' is open. Both clutch devices 2 and 2' must not fully close at the same time, otherwise the transmission will lock.

[0077] During an overlap shift, which serves to shift without interruption of traction, both clutch devices 2 and 2' are briefly partially closed or are in slipping mode. Thus, drive torque can be transmitted to the drive wheels even during the shift. The following describes, as an example, a gear change from first to second gear, i.e., with the first clutch device 2 initially closed and the second clutch device 2' open. During the overlap shift, the first clutch device 2 is opened and the second clutch device 2' is closed.

[0078] Fig. 7 shows an example of the temporal sequence of an overlap shift of the dual-clutch transmission, in which the actuating element 9, which is displaceable in the axial direction x, acts at least indirectly with a further force on the element 3' of the second clutch device 2'. The axial position 24 of the actuating element 9 or the actuator, as well as the axial position 25 of the piston 4 and the axial position 26 of the piston 4' are shown over time t. Due to elasticities in the plate pack of the respective clutch devices 2 or 2' or additional spring elements acting in the axial direction, the axial position of the piston 4 and the total force or normal force F3 on the plate pack 3 of the first clutch device 2, as well as the axial position of the piston 4' and the total force or normal force F3' on the plate pack 3' of the second clutch device 2' are related via spring characteristics.At time ti, the first clutch device 2 is still completely closed at an axial actuator position x = x, the piston 4 is at the same position x. ± . The piston 4' is, as shown in Fig. 6, in the left rest position x 20. At the beginning of the overlap shift, the actuator moves quickly towards the piston 4' and at time t2 comes into contact with the piston 4' and closes its drain bore 17. Here, the actuator reduces its speed and displaces the piston 4' to the right, whereby the clearance of the plate pack 3' of the second clutch device 2' is overcome. From time ta, the second clutch device 2' begins to transmit torque in slipping operation. At the beginning of the closing process of the second clutch device 2', its pressure chamber 11 is not yet filled with the pressure medium; this only occurs with a delay through the at least one inlet bore 12 after the at least one drain bore 17 has been closed by the actuating element 9. At the beginning of the closing process of the second clutch device 2', the pressure p' acting on the piston 4' and a resulting piston force F1 ' are still close to zero.Thus, the temporal closing process of the second clutch device 2' is determined exclusively and very precisely by the actuating element 9 or the actuator, or by the temporal progression of the axial position of the actuating element 9 or the actuator. At time ts, the second clutch device 2' is then completely closed at an axial actuator position x = x2, and the piston 4' is at the same position x2.

[0079] During the entire process, the first clutch device 2 opens. This begins at the time t1, at which the actuator or the actuating element 9 moves away from the piston 4 and opens its at least one drain hole 17. The piston 4 is then pushed by one or more springs or spreading springs (not shown) towards its right rest position x 10moves. The temporal progression of the position of the piston 4 is determined by the volume flow of the pressure medium via the at least one drain hole 17 and / or the volume flow of the pressure medium via the at least one inlet hole 12. As explained above, these can be influenced depending on the current speed of the shaft 5, the current rotational pressure p, the volume of the pressure medium currently contained in the pressure chamber 11 and / or the current total force or normal force F3 on the disk pack, etc., in order to design the opening process favorably and adapt it to the current driving condition. The use of solenoid valves to influence the volume flow of the pressure medium via the at least one drain hole 17 and / or the volume flow of the pressure medium via the at least one inlet hole 12, which are controlled by the transmission control, is also possible.These can be installed in the rotating system component or, using rotary joints, in the non-rotating system component. At time t4, the piston 4 reaches a position at which the first clutch device 2 no longer transmits torque and at time ts reaches its right rest position x. 10according to Fig. 1 . Thus, the temporal opening process of the first clutch device 2 or the temporal progression of the pressure p acting on the piston 4 and in this way the first force or piston force F1 and / or the axial position of the piston 4 is predetermined by throttling the volume flow of the pressure medium via the at least one drain bore 17 and / or the at least one inlet bore 12. The volume flows of the pressure medium via the at least one drain bore 17 and / or via the at least one inlet bore 12 influence the filling of the pressure chamber 11 or the volume of the pressure medium contained therein and thus the temporal progression of the rotational pressure p or the piston force F1 of the piston 4 and thus the total force or normal force F3 on the disk pack 3 of the first clutch device 2. As described above, the axial position of the piston 4 and the total force orNormal force F3 on the disk pack 3 of the first clutch device 2 due to elasticities in the disk pack 3 of the clutch device 2 or additional spring elements acting in the axial direction via spring characteristics.

[0080] As described above, the opening process of the first clutch device 2, i.e. the temporal specification of the axial position of the piston 4 and / or the total force or normal force F3 on the plate pack of the first clutch device 2, is controlled by the volume flow of the pressure medium via the at least one drain bore 17 and / or the at least one inlet bore 12. I.e. the temporal profile of the axial position of the piston 4 is specified by throttling the volume flow of the pressure medium via the at least one drain bore 17 and / or the at least one inlet bore 12. The closing process of the second clutch device 2', i.e. the temporal specification of the axial position of the piston 4' and / or a total force or normal force F3' on an element or plate pack 3' of the second clutch device 2', is specified by the actuating element 9 or the actuator.In other words, the actuating element 9, which is displaceable in the axial direction x, specifies the temporal closing process of the element 3 of the second coupling device 2' and, at the same time, the piston 4 specifies the temporal opening process of the element 3 of the first coupling device 2 by specifying the temporal course of the axial position of the piston 4 by throttling the volume flow of the pressure medium via the at least one inlet bore 12 and / or the at least one outlet bore 17.

[0081] Thus, only one actuator is required, and both the device 1 for controlling the clutch device 2 and the method for controlling the clutch device 2 can be implemented more cost-effectively. The actuating element 9 or the actuator acts on the two clutch devices 2 and 2' in such a way that simultaneous, complete engagement of both clutch devices 2 and 2' is prevented. Transmission locking is thus prevented, resulting in high driving safety.

[0082] In a further development of this method, starting at time ti, the actuating element 9 or the actuator can initially move slowly to the right, so that the piston 4 can follow and move together with the actuator. The actuator separates from the piston 4 at an actuator position x with x 10 < x < x x, shortly before the opening first clutch device 2 begins to slip. This actuator position depends on the current drive torque and is selected such that the actuator brings the closing second clutch device 2' into slipping operation at a time at which the opening first clutch device 2 also begins to slip, the opening behavior of which or the temporal progression of the position of the piston 4 is then predetermined by throttling the volume flow of the pressure medium via the at least one outlet bore 17 and / or via the at least one inlet bore 12. This allows the overlap switching to be coordinated even better.

[0083] In another development of this method, the actuating element 9 or the actuator is influenced depending on the opening process of the opening clutch device 2. This can be achieved, for example, by selecting the time ts, at which the second clutch device 2' begins to transmit torque in slipping operation, such that the opening first clutch device 2 begins to slip at the same time. Furthermore, it can be advantageous if the closing second clutch device 2' generates the driver-desired torque at the drive wheels at the time t4, at which the opening first clutch device 2 no longer transmits torque. The drive torque of the electric machine can contain further torque components in order to carry out rotational acceleration or synchronization by equalizing the speeds between the outer and inner plates of the closing second clutch device 2'.The opening process of the opening clutch device 2 or 2' can be calculated using a dynamic mathematical model in the control device, and based on this, the actuator for the closing process of the closing clutch device 2 or 2' can be controlled. The mathematical model receives, for example, the determined current speed of shaft 5, the current temperature of the pressure medium and thus its viscosity, as well as the current axial actuator position x. In addition, the current rotational pressures, the piston positions, the differential speeds between the outer and inner plates of the two clutch devices 2 or 2', as well as the drive torque, can be determined. The dynamic mathematical model can calculate and / or estimate and / or observe the volume of the pressure medium currently contained in the pressure chamber 11 and / or the pressure or rotational pressure p and / or the first force or piston force F1.With this information, the actuator can be controlled more effectively.

[0084] Another development of this method is provided for a pull-down shift from second gear to first gear. This is done by opening the second clutch device 2' and closing the first clutch device 2. In this case, it is possible for the actuating element 9 or the actuator to separate from the piston 4' of the second clutch device 2' at an actuator position x with x2 < x < x 20, in which the opening second clutch device 2' is already slipping. The actuator can therefore precisely specify the torque transmitted in the slipping state of the second clutch device 2', while the electric machine carries out synchronization by adjusting the speeds between the outer and inner plates of the closing first clutch device 2. After the speed has been adjusted, the actuator is separated from the piston 4' of the second clutch device 2', after which the opening behavior or the temporal progression of the position of the piston 4' is specified by throttling the volume flow of the pressure medium via the at least one outlet bore 17 and / or via the at least one inlet bore 12 and the actuator then specifies the closing process of the first clutch device 2, i.e. the temporal specification of the axial position of the piston 4. A corresponding method can also be used for overrun upshifts.

[0085] In another development of this method, the actuating element 9 or the actuator is provided to additionally actuate a parking lock.

Claims

Patent claims Device (1) for controlling a clutch device (2, 2'), with a piston (4, 4') which is displaceable in the axial direction (x) for applying a first force (F1) to an element (3, 3') of the clutch device (2, 2') by means of a pressure (p) acting on the piston (4, 4'), characterized by an actuating element (9) which is displaceable in the axial direction (x) and acts at least indirectly with a second force (F2) on the element (3, 3') of the clutch device (2, 2'), wherein the actuating element (9) is provided to control the pressure (p) acting on the piston (4, 4') and in this way the first force (F1), wherein the first force (F1) and the second force (F2) result in a total force (F3) acting on the element (3, 3') of the clutch device (2, 2').Device (1) according to claim 1, characterized in that the actuating element (9) controls the pressure (p) acting on the piston (4, 4') by influencing an inlet and / or outlet of a pressure medium. Device (1) according to claim 1 or 2, characterized in that the actuating element (9) acts via the piston (4, 4') with the second force (F2) on the element (3, 3') of the coupling device (2, 2'). Device (1) according to claim 1, 2 or 3, characterized in that the pressure (p) acting on the piston (4, 4') is generated by means of centrifugal force by a pressure medium rotating in a pressure chamber (11) adjacent to the piston (4, 4').Device (1) according to claim 4, characterized in that a reservoir (13) for the pressure medium is formed by a hollow space in a rotatable shaft (5), wherein the reservoir (13) for the pressure medium is connected to the pressure chamber (11) via at least one inlet bore (12) provided on the outer surface of the shaft (5) in such a way that the pressure medium is supplied to the pressure chamber (11) by centrifugal force. Device (1) according to one of claims 1 to 5, characterized in that the actuating element (9) is designed as an engagement or release bearing arranged on a rotatable shaft (5) and displaceable in the axial direction (x) by means of an actuator.

7. Device (1) according to one of claims 1 to 6, characterized in that the piston (4, 4') has at least one drain hole (17) which can be closed by means of the actuating element (9).

8. Device (1) according to claim 7, characterized in that a device (18) for changing the cross-section of the drain hole (17) is arranged within the same.

9. Device (1) according to one of claims 1 to 8, characterized in that the element (3, 3') of the coupling device (2, 2') is designed as a friction element.

10. Method for controlling a clutch device (2, 2'), wherein an element (3, 3') of the clutch device (2, 2') is subjected to a first force (F1) by means of a piston (4, 4') displaceable in the axial direction (x) by means of a pressure (p) acting on the piston (4, 4'), characterized in that an actuating element (9) displaceable in the axial direction (x) acts at least indirectly with a second force (F2) on the element (3, 3') of the clutch device (2, 2'), and in that the actuating element (9) is provided to control the pressure (p) acting on the piston (4, 4') and in this way the first force (F1), wherein the first force (F1) and the second force (F2) result in a total force (F3) acting on the element (3, 3') of the clutch device (2, 2').

11. Method according to claim 10, characterized in that the actuating element (9) acts via the piston (4,4') with the second force (F2) on the element (3,3') of the coupling device (2,2').

12. Method according to claim 10 or 11, characterized in that the pressure (p) acting on the piston (4,4') is generated by means of centrifugal force by a rotating pressure medium, wherein the pressure medium is supplied to a pressure chamber (11) adjacent to the piston (4,4') by means of centrifugal force from a cavity of a rotatable shaft (5).

13. Method according to claim 12, characterized in that a dynamic mathematical model is stored in a control device, which calculates and / or estimates and / or observes the volume of the pressure medium currently contained in the pressure chamber (11) and / or the pressure (p) and / or the first force (F1).

14. Method according to one of claims 10 to 13, wherein the clutch device (2, 2') is a component of a dual-clutch transmission, characterized in that the actuating element (9) which is displaceable in the axial direction (x) acts at least indirectly with a further force on an element (3, 3') of a second clutch device (2, 2') during an overlap shift of the dual-clutch transmission.

15. Method according to claim 14, characterized in that the actuating element (9) which is displaceable in the axial direction (x) specifies the temporal closing process of the element (3, 3') of the second coupling device (2, 2') and at the same time the piston (4, 4') specifies the temporal opening process of the element (3, 3') of the first coupling device (2, 2') in that the temporal course of the pressure (p) acting on the piston (4, 4') and in this way the first force (F1) and / or the axial position of the piston (4, 4') is specified by throttling the volume flow of the pressure medium via at least one inlet bore (12) and / or at least one outlet bore (17).

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