Dual clutch and drive system provided therewith

Abstract

The invention relates to a dual clutch (10) and a drive system, having a first clutch (12a) and a second clutch (12b), wherein the first clutch (12a) and the second clutch (12b) can each be actuated by means of hydraulic pistons (28a, 28b) against a respective spring force (44a, 44b), the first clutch (12a) is arranged coaxially and substantially mirror-symmetrically to the second clutch (12b), a first (34a) and a second piston chamber (34b) of the clutches (12a, 12b) have a common piston chamber rear wall (14), first outer discs (26a) of the first clutch (12a) are connected in a rotationally fixed manner to a first outer disc holder (30a) and second outer discs (26b) of the second clutch (12b) are connected in a rotationally fixed manner to a second outer disc holder (30b), first inner discs (22a) and second inner discs (22b) are connected in a rotationally fixed manner to a common inner disc carrier (20), characterised in that the first (22a) and the second inner discs (22b) are axially secured to the inner disc carrier (20) and each have inner fastening regions (45) and radially outer friction regions (49) which are connected via a number of resilient connecting webs (51), so that, in the coupled state, the friction regions (49) are axially offset relative to the fastening regions (45) with elastic deformation of the connecting webs (51), and wherein the piston chamber rear wall (14) and the pistons (28a, 28b) are arranged axially between the first (22a) and second (22b) inner discs, wherein the piston chamber rear wall (14) is supported on the inside of the inner disc carrier (22). This enables the use of multi-disc clutches in the high-speed range with electric drive machines.

Description

[0001] Dual clutch and drive system

[0002] The invention relates to a dual clutch with a first clutch and a second clutch, wherein the first clutch and the second clutch are each actuated by means of hydraulic pistons against a spring force, the first clutch is arranged coaxially and substantially mirror-symmetrically to the second clutch, a first and a second piston chamber of the clutches have a common piston chamber rear wall, first outer plates of the first clutch are connected in a rotationally fixed manner to a first outer plate holder and second outer plates of the second clutch are connected in a rotationally fixed manner to a second outer plate holder, first inner plates and second inner plates are connected in a rotationally fixed manner to a common inner plate carrier. The invention further relates to a drive system with such a dual clutch.

[0003] Such a dual clutch is known from DE 102013204 974 A1 and is used to supply the drive torque alternatively to one of two transmission input shafts in the drive train between an internal combustion engine and a dual clutch transmission.

[0004] In this dual clutch, both the inner and outer plates are arranged in rotationally fixed but axially movable inner and outer plate carriers, and piston chambers for the plate pairs and piston springs are arranged radially inside the inner plates.

[0005] From DE 102016 014672 A1 a clutch for an automatic transmission of a motor vehicle is known in which internal plates are connected axially and rotationally fixed to an inner plate carrier.

[0006] DE 102021 006 124 B3 describes a drive concept with two electric drive motors and two drive wheels of a common drive axle, actuated via reduction gears. Conventional dual clutches in electric motor drives have so far been operated at wheel speed, i.e., after a corresponding gear ratio, due to the centrifugal force problems that occur in the high-speed range. The reason for this lies, on the one hand, in the stationary actuation of the clutch mechanism, which would lead to very high losses at higher speeds, and, on the other hand, in the high component loads, which can become supercritical for individual clutch components at the high speeds of electric motor drives.

[0007] The object of the invention is to provide a dual clutch for an electric drive system of a motor vehicle according to the preamble of claim 1, which enables use at high speeds, which are particularly common in electric drive motors. Above all, the dual clutch is intended to be used to enable a defined distribution of torque from an electric drive motor to the drive wheels (so-called torque vectoring).

[0008] The invention is based on the features of the independent claims. Advantageous developments and refinements are the subject of the dependent claims.

[0009] The object is achieved according to claim 1 in that the first and the second inner plates are connected axially fixed to the inner plate carrier and each have inner fastening regions and radially outer friction regions which are connected via a number of resilient connecting webs, so that the friction regions are axially offset in relation to the fastening regions in the coupled state with deformation of the connecting webs, and wherein the piston chamber rear wall and the pistons are arranged axially between the first and second inner plates and are supported on the inside on the inner plate carrier.

[0010] The inventive arrangement of the inner plates, axially fixed to an inner plate carrier, makes the use of multi-plate clutches possible in the high-speed range, i.e., for applications with electric drive motors operating at up to 20,000 rpm, for which conventional multi-plate clutches are difficult to design with a fixed speed. The invention thus allows the multi-plate clutch to operate at the engine speed of the electric drive motor(s), eliminating the need to reduce the clutch speed by means of an upstream transmission.A gearbox or, in particular, a gear stage for reducing the high speeds of the drive engine(s) to the speeds of the motor vehicle's wheels is provided on the output side of the dual clutch, whereby the torque that the multi-plate clutches of the dual clutch have to transmit is comparatively low, so that fewer pairs of plates are required for power transmission, which reduces the axial size of the dual clutch. This in turn enables the actuating pistons with pressure chamber to be arranged axially between the two mirror-symmetrical clutches and enables an extremely compact size of the dual clutch, also in radial terms, so that space is created radially within the dual clutch for additional parts, in particular a planetary gear differential. The invention also enables a compact design because the transmission torques can be introduced and discharged on one side.The mirror-symmetrical design of the transmission-relevant clutch components ensures similar transmission characteristics and thus good controllability of both clutches. An electro-hydraulic clutch design enables low-loss operation, since an electromechanical design would result in high differential speeds between the actuator and the clutch piston, which would have to be transmitted via an axial bearing.

[0011] According to an advantageous embodiment of the invention, the piston chamber rear wall consists of a support disk attached to the inner disk carrier and a radially externally formed guide sleeve with two piston guides for the pistons formed on its outer circumference. Pressure chambers are formed for the introduction of pressurized oil between the pistons and the piston chamber rear wall. This design, together with the symmetrical structure, enables more reliable, more precise, and better controllable piston movements and thus reproducible control quality with electrohydraulic control.

[0012] According to an advantageous development of the invention, each piston has an annular thrust projection extending axially radially outside the respective piston guide, via which the respective inner and outer plates can be brought into frictional engagement with one another. This enables more precise and better controllable piston movements. Preferably, the outer piston guides of the pistons are arranged in the outer third of the force application point radii of the thrust projections, which enables more reliable, more precise, and better controllable piston movements.

[0013] According to an advantageous development of the invention, the clutches each have a spring support fixed to the inner plate carrier for supporting a piston spring and for forming a centrifugal oil chamber arranged between the piston and the spring support. The arrangement of centrifugal oil chambers between the pistons and the spring supports ensures reliable centrifugal force compensation, resulting in more precise piston control, which is particularly important given the high speeds involved in electric drives. At the same time, in this development, the piston spring is located inside the centrifugal oil chamber, further increasing the compactness of the design. The centrifugal oil chambers are preferably sealed from the environment by means of sealing rings, so that the spring supports also serve to separate the centrifugal oil chambers from the space containing the plates.

[0014] According to an advantageous development of the invention, the inner disk carrier is constructed in two parts and consists of two support elements arranged axially one behind the other. Evenly spaced fixing screws firmly connect the support elements, the piston chamber rear wall, the spring supports, the inner disks, the spacers, and the counterholders as counterbearings for the axial compressive force generated by the pistons. This ensures a secure connection that is easy to install, yet allows for easy disassembly to replace defective components in the event of damage.

[0015] The problem is further solved by a drive system with two electric drive motors using a dual clutch, as described above. The dual clutch can be coupled directly to the drive motors without the need for intermediate reduction gears, thus requiring only comparatively lower torques to be transmitted by the dual clutch, which is made possible by the design of the dual clutch according to the invention. The smaller number of plates for torque transmission therefore provides a very compact drive system.

[0016] According to an advantageous development of this embodiment, the inner disk carrier can be coupled to a first electric drive motor. The coupling is preferably effected via a claw clutch between the rotor of the electric drive motor and the inner disk carrier. According to the invention, such a coupling is effected without an intermediate transmission, so that the dual clutch rotates at the speed of the electric drive motor, i.e., in the range of 10,000-20,000 rpm. As already explained above, such a drive system is feasible due to the high speeds achieved by the dual clutch designed according to the invention.Due to the high speed in the dual clutch, the inventive design transmits only a relatively low torque, so that the number of plate pairs can be kept low, resulting in a very compact overall construction consisting of two electric drive motors and the dual clutch arranged between them. According to an advantageous further development of this design, the inner plate carrier can be coupled to a first electric drive motor, i.e., without a transmission gear to reduce the speed in the dual clutch.

[0017] According to an advantageous further development of this design, the first outer disk holder forms an output to a first drive gear via a first output shaft, and the second outer disk holder forms an output to a second drive gear via a second output shaft, with the first and second drive gears being assigned to a common drive axle. This design enables a very compact axial design of the overall structure. Preferably, transmission gears are installed upstream of the drive gears to reduce the high speed of the electric drive motors to the speed range of the drive gears.

[0018] Further advantages, features, and details will become apparent from the following description, which describes an exemplary embodiment in detail—with reference to the drawings, if appropriate. Identical, similar, and / or functionally equivalent parts are provided with the same reference numerals.

[0019] They show:

[0020] Figure 1: a perspective axial section of a double clutch with surroundings; Figure 2: a partial axial section of the double clutch of Figure 1;

[0021] Figure 3: a schematic representation of the double clutch of Figures 1 and 2;

[0022] Figure 4: a view of an inner lamella;

[0023] Figure 5: a schematic representation of a drive system with the dual clutch and two electric drive motors.

[0024] Figures 1, 2, and 3 depict a dual clutch 10 consisting of two clutches 12a, 12b arranged axially one behind the other in mirror symmetry with respect to a piston chamber rear wall 14. Figure 2 shows the left clutch 12a from Figure 1 in an enlarged detail; the right clutch 12b is constructed in a mirror image.

[0025] An input torque is introduced into the dual clutch 10 via an input shaft 16 and transmitted to an inner disk carrier 20 consisting of two carrier elements 18a, 18b. The essentially disc-like piston chamber rear wall 14 is fitted between the two carrier elements 18a, 18b. The two clutches 12a, 12b each consist of a number of inner disks 22a, 22b, between which spacers 24a (the spacers in the right-hand clutch 12b are not shown in Fig. 1 for reasons of clarity) are arranged, and a number of outer disks 26a, 26b, which can be brought into frictional contact with the inner disks 22a, 22b.

[0026] The outer plates 26a of the first clutch 12a shown on the left are held in a first outer plate holder 30a in a rotationally fixed but axially displaceable manner. The first outer plate holder 30a is part of a first output shaft 32. The outer plates 26b of the second clutch 12b shown on the right are held in a similar manner in a second outer plate holder 30b in a rotationally fixed but axially displaceable manner. The second outer plate holder 30b is part of a second output shaft 36.

[0027] The two clutches 12a, 12b are actuated by two pistons 28a, 28b, which are axially guided via an outer piston guide 29a on the common piston chamber rear wall 14 and an inner piston guide 29b on the inner disk carrier 20. Between the piston chamber rear wall 14 and the two pistons 28a, 28b, two piston chambers 34a, 34b are formed, which are individually pressurized with oil, so that the pistons 28a, 28b can move axially from the piston chamber rear wall 14 and press with two annular pressure projections 38a, 38b against the disk packs consisting of the inner disks 22a, 22b and the outer disks 26a, 26b alternating with them. The outer piston guides 29a of the pistons 28a, 28b are arranged in the outer third of the force application point radii of the pressure projections 38a, 38b.

[0028] Two counterholders 40a are attached to the two support elements 18a, 18b forming the inner disk carrier 22, which act as counterbearings for the axial pressure forces applied by the two annular pressure projections 38a, 38b and thus cause a frictional engagement between the inner disks 22a, 22b and the outer disks 26a, 26b alternating therewith.

[0029] Between the pistons 28a, 28b and the two associated clutches 12a, 12b, two spring supports 42a, 42b are provided, which are fastened to the inner disk carrier 22. Between each spring support 42a, 42b and an associated piston 28a, 28b, extend two centrifugal oil chambers 46a, 46b, which are filled with unpressurized oil and compensate for the additional pressure increase caused by the centrifugal forces in the piston chambers 34a, 34b, since the centrifugal oil chambers 46a, 46b are arranged on the axial sides of the pistons 28a, 28b opposite the piston chambers 34a, 34b. The centrifugal oil chambers 46a, 46b are sealed from the piston chambers 34a, 34b and the chamber with the vanes 22, 26 by means of sealing rings 43. Two piston springs 44a, 44b are arranged inside the centrifugal oil chambers 46a, 46b, which move the respective piston 28a, 28b toward the piston chamber rear wall 14 when the oil pressure in the associated piston chamber 34a, 34b is reduced.

[0030] The counterholders 40a, 40b, the inner plates 22a, 22b with the spacers 24a, 24b arranged therebetween, and the two support elements 18a, 18b with the piston chamber rear wall 14 arranged therebetween are firmly screwed together by means of evenly spaced fixing screws 48, so that the inner plates 22a, 22b are not axially displaceable.

[0031] When the clutches 12a, 12b are disengaged, the piston chambers 34a, 34b are depressurized, so that the piston springs 44a, 44b press the pistons 28a, 28b towards the piston chamber rear wall 14. Axial gaps exist between the inner plates 22a, 22b and the adjacent outer plates 26a, 26b. As shown in Figure 4, the inner plates 22a, 22b each consist of a radially inner fastening area 45 with openings 47 for the passage of the fixing screws 48 and a radially outer annular friction area 49, which serves on both sides of the inner plates 22a, 22b to enter into frictional engagement with friction areas of the outer plates 26a, 26b located at the same radial height. The fastening area 45 and the friction area 49 of each inner plate 22a, 22b are connected to each other by a number of flexible, S-shaped connecting webs 51.When the clutches 12a, 12b are open, the inner plates 22a, 22b are flat discs that extend precisely in a radial direction. If a clutch 12a is engaged by directing pressurized oil into the corresponding piston chamber 34a, this moves the piston 28a against the force of the piston spring 44a, so that the pressure projection 38a of the piston 28a presses against the plate pack consisting of inner plates 22a and outer plates 26a, which in turn is supported by the counterholder 40a. While the outer plates 26a can move axially in the outer plate holder 30a, this does not apply to the inner plates 22a, which are axially fixedly mounted on the inner plate carrier 20.The S-shaped connecting webs 51 deform elastically when the friction areas 49 of the inner plates 22a are axially displaced by the pressure projection 38a together with the outer plates 26a, whereby a friction connection is created between the inner plates 22a and the outer plates 26a and thus the clutch 12a engages.

[0032] Figure 5 shows an application of the dual clutch 10 as a component of a drive system 50 with two electric drive motors 52a, 52b, a planetary differential gear 54, two planetary gear sets 56a, 56b and two drive wheels 58a, 58b.

[0033] A first electric drive motor 52a is connected to a ring gear 53 of the planetary differential gear 54, whose sun gear is coupled via the planetary gear set 56b to the right-hand drive gear 58b in Figure 5. The planet carriers of the planetary differential gear 54 are connected via the second output shaft 36 to the second clutch 12b and to the planetary gear set 56a of the left-hand drive gear 58a in Figure 5.

[0034] An input shaft 16 of the dual clutch 10 can be coupled to the second electric drive motor 52b via a claw clutch 57. The input shaft 16 is connected to the first output shaft 32 by actuating the first clutch 12a, which is also coupled to the right-hand drive gear 58b in Figure 5 via the planetary gear set 56b.

[0035] When the first clutch 12a is engaged (and the second clutch 12b remains disengaged), the input shaft 16 of the second electric drive motor 52b is connected to the first output shaft 32 in such a way that the torque of the second electric drive motor 52b is introduced into the first output shaft 32 and thus into the right drive wheel 58b in Figure 5, bypassing the second output shaft 36.

[0036] If, however, the second clutch 12b is alternatively engaged (and the first clutch 12b is disengaged for this purpose), the torque of the second electric drive motor 52b is introduced via the input shaft 16 into the second output shaft 36 and thus into the drive gear 58a on the left in Figure 5. This enables torque vectoring operation, in which different torques can be specifically supplied to the two output shafts 32, 36 or drive gears 58a, 58b.

[0037] Although the invention has been illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned by way of example are truly only examples and should not be construed as limiting the scope, possible applications, or configuration of the invention in any way.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without departing from the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

[0038] List of reference symbols

[0039] 10 Dual clutch

[0040] 12a, b couplings

[0041] 14 Piston chamber rear wall

[0042] 16 Input shaft

[0043] 18a,b support elements

[0044] 20 inner disc carriers

[0045] 22a, b inner slats

[0046] 24a, b spacers

[0047] 26a, b outer slats

[0048] 28a, b piston

[0049] 29a, b Piston guides

[0050] 30a, b outer slat holder

[0051] 32 first output shaft

[0052] 34a, b piston chamber

[0053] 36 second output shaft

[0054] 38a, b pressure projections

[0055] 40a, b Counterholder

[0056] 42a, b spring supports

[0057] 43 sealing rings

[0058] 44a, b piston springs

[0059] 45 Mounting area

[0060] 46a, 46b Centrifugal oil rooms

[0061] 47 openings

[0062] 48 fixing screws

[0063] 49 Friction area

[0064] 50 drive system

[0065] 51 connecting bridges

[0066] 52a, b electric drive machines

[0067] 53 ring gear

[0068] 54 planetary differential gears

[0069] 56a, b Planetary gear sets

[0070] 57 Claw coupling

[0071] 58a, b drive wheels

Claims

Patent claims 1. Double clutch (10) for an electric drive system of a motor vehicle with a first clutch (12a) and a second clutch (12b), wherein - the first clutch (12a) and the second clutch (12b) can each be actuated by means of hydraulic pistons (28a, 28b) against a spring force (44a, 44b), - the first coupling (12a) is arranged coaxially and substantially mirror-symmetrically to the second coupling (12b), - a first (34a) and a second piston chamber (34b) of the clutches (12a, 12b) have a common piston chamber rear wall (14), - first outer plates (26a) of the first clutch (12a) are connected in a rotationally fixed manner to a first outer plate holder (30a) and second outer plates (26b) of the second clutch (12b) are connected in a rotationally fixed manner to a second outer plate holder (30b), - first inner plates (22a) and second inner plates (22b) are connected in a rotationally fixed manner to a common inner plate carrier (20), characterized in that the first (22a) and the second inner plates (22b) are fastened axially fixedly to the inner plate carrier (20) and each have radially inner fastening regions (45) and radially outer friction regions (49) which are connected via a number of resilient connecting webs (51), so that the friction regions (49) in the coupled state are axially offset with respect to the fastening regions (45) with elastic deformation of the connecting webs (51), and wherein the piston chamber rear wall (14) and the pistons (28a, 28b) are arranged axially between the first (22a) and second (22b) inner plates, wherein the piston chamber rear wall (14) is supported on the inside on the inner plate carrier (20).

2. Double clutch according to claim 1, characterized in that the piston chamber rear wall (14) consists of a support disc fastened to the inner disk carrier and a guide sleeve formed radially on the outside with two piston guides for the pistons (28a, 28b) formed on its outer circumference, wherein the piston chambers (34a, 34b) are designed for the introduction of pressurized oil between the pistons (28a, 28b) and the piston chamber rear wall (14).

3. Double clutch according to claim 2, characterized in that each piston (28a, 28b) has an annular pressure projection (38a, 38b) extending axially radially outside the respective radially outer piston guide (29a), via which the respective inner (22a, 22b) and outer plates (26a, 26b) can be brought into frictional engagement with one another.

4. Double clutch according to claim 3, characterized in that the outer piston guides (29a) of the pistons (28a, 28b) are arranged in the outer third of the force application point radii of the pressure projections (38a, 38b).

5. Double clutch according to one of claims 2 to 4, characterized in that the clutches (12a, 12b) each have a spring support (42a, 42b) fixed to the inner disk carrier (20) for supporting a piston spring (44a, 44b) and for forming a centrifugal oil chamber (46a, 46b) arranged between the piston (28a, 28b) and the spring support (42a, 42b).

6. Double clutch according to claim 5, characterized in that the centrifugal oil chambers (46a, 46b) are sealed from the environment by sealing rings (43).

7. Double clutch according to one of the preceding claims, characterized in that the inner disk carrier (20) is designed in two parts and consists of two axially successively arranged carrier elements (18a, 18b), wherein evenly spaced fixing screws (48) fix the carrier elements (18a, 18b), the piston chamber rear wall (14), the spring supports (42a, 42b), the inner disks (22a, 22b), the spacer (24a, 24b) and counterholder (40a, 40b) as counterbearings for the axial pressure force generated by the pistons (28a, 28b), firmly connected to one another.

8. Electric drive system with two electric drive motors (52a, 52b) and a double clutch (10) according to one of the preceding claims, characterized in that the double clutch (10) can be coupled directly to the drive motors (52a, 52b) without the interposition of reduction gears.

9. Electric drive system according to claim 8, characterized in that the inner disk carrier (20) can be coupled to a first electric drive machine (52b) via a clutch, preferably a claw clutch.

10. Electric drive system according to claim 8 or 9, characterized in that the first outer disk holder (30a) forms an output to a first drive wheel (58b) via a first output shaft (32) and the second outer disk holder (30b) forms an output to a second drive wheel (58a) via a second output shaft (36), wherein the first and the second drive wheel (58a, 58b) are assigned to a common drive axle.

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