Multi-plate clutch and friction plate for same

Abstract

The invention relates to a multi-plate clutch (1) and a friction plate (7) for the latter for wet operation by means of a fluid, comprising a plate pack (6) which is arranged about an axis of rotation (d) of the multi-plate clutch (1) and can be loaded axially in order to form a frictional connection and which is composed of alternately axially layered friction plates (7) and counter plates (8), wherein the friction plates (7) are rotationally fixed to a first plate carrier and the counter plates (8) are rotationally fixed to a second plate carrier (2, 3), and a respective one plate carrier (2, 3) is assigned to an input part and the other plate carrier (2, 3) is assigned to an output part of the multi-plate clutch, wherein the friction plates (7) contain a carrier disc (11) with friction segments (12) arranged on both sides. In order to be able to produce multi-plate clutch (1) of this type with low drag torque and at low cost, four to eight, preferably six, friction segments (12) are provided, distributed over the circumference, with first embossments (13) formed axially at their circumferential ends, and the first embossments (13) form an expanded passage space (19) for the fluid by means of radial gaps (15) spacing the friction segments (12) apart from one another in the circumferential direction.

Description

[0001] Multi-plate clutch and friction plate for this

[0002] The invention relates to a multi-plate clutch and a friction plate for this for wet operation with a plate pack arranged around a rotational axis of the multi-plate clutch and axially loadable to form a frictional connection, consisting of alternately axially layered friction plates and counter plates, wherein the friction plates are rotationally fixed to a first and the counter plates to a second plate carrier, and a first plate carrier is assigned to an input part and the other plate carrier to an output part of the multi-plate clutch, wherein the friction plates include a carrier disc with friction segments arranged on both sides.

[0003] Documents EP 1 876 369 A2, EP 2 551 543 A1, and WO 2022 / 111750 A1 each disclose friction plates for wet, fluid-operated (e.g., oil) multi-plate clutches, with friction segments arranged on both sides and distributed around the circumference. A plurality of more than sixteen friction segments is mounted on a carrier disc, maintaining a radial gap. The number of friction segments essentially corresponds to, or is only slightly less than, the number of teeth of a toothed section on the carrier disc for the rotationally fixed mounting of the friction plate. Each of these friction segments is positioned and mounted on the carrier disc, forming a radial gap to the next friction segment along the circumference.

[0004] Within at least a portion of the friction segments, various indentations are provided to form fluid paths, particularly when the multi-plate clutch is closed and several friction plates are axially pre-tensioned, alternating with counter plates to form a plate pack. These fluid paths partially correspond to fluid openings in the associated plate carrier of the multi-plate clutch and / or in the carrier disc to achieve improved fluid flow across the plate pack.

[0005] The multi-plate clutches containing these friction plates are used, for example, in hybrid or purely electric drive trains as so-called separator clutches, which connect and disconnect two electric motors or a drive unit consisting of an internal combustion engine and an electric motor with another electric motor. For the quality of the drive train control, it is essential that the multi-plate clutch exhibits a low load torque in the open state and that precise load torque behavior occurs during switching operations, especially at high speeds.

[0006] The object of the invention is the further development of a multi-plate clutch and the friction plates for it. In particular, the object of the invention is to propose a multi-plate clutch and friction plates for it which are, on the one hand, cost-effective to manufacture and, on the other hand, can be operated with low drag torques.

[0007] The problem is solved by combining the features of the subject matter of claims 1 and 3. The dependent claims describe advantageous embodiments of the subject matter of claims 1 and 3.

[0008] The proposed multi-plate clutch is designed for wet operation, for example, cooled with a fluid such as oil, ATF, or the like. Preferably, the proposed multi-plate clutch is used as a disconnect clutch, similar to a separator clutch, in a hybrid or purely electric powertrain of a motor vehicle, connecting and disconnecting two electric motors, particularly at high speeds. The multi-plate clutch is arranged around a rotational axis and includes an input-side and an output-side plate carrier, each with an axial projection, for example, a cup-shaped one.Radially between these approaches, a lamellar pack consisting of axially alternating friction and counter-lamellae is arranged. The counter-lamellae and the friction lamellae are each rotationally fixed or interlocked, for example, by forming corresponding profiles such as serrations, within a lamellar carrier, thus forming the lamellar pack. Frictional engagement of the lamellar clutch, and therefore torque transmission, is achieved by axially applying pressure to the lamellar pack, thereby clamping the counter-lamellae and friction lamellae against each other.

[0009] Preferably, the counter-lamellae are formed from metal discs, such as metal rings with friction surfaces, while the friction lamellae comprise a carrier disc with friction segments arranged on both sides. The two axial projections of the lamella carrier are preferably arranged radially one above the other and have mutually facing profiles, such as molded-on teeth. Preferably, the friction lamellae are rotationally fixed in the radially inner projection and therefore have internal teeth, while the counter-lamellae suspended in the radially outer projection have external teeth. It is understood that, conversely, the friction lamellae can be suspended in the radially outer projection of the associated lamella carrier and have external teeth.The trouble-free transmission of torque when the multi-plate clutch is closed, as well as a reduction of drag torque when the multi-plate clutch is opening or open, depends on a variety of parameters, in particular the design such as shape and material of the friction segments and temperature-dependent properties of the fluid.

[0010] To design the multi-plate clutch cost-effectively and with optimized drag torque, the friction plates are equipped with a combination of several features that, in total, improve the drag torque without compromising cost-effective manufacturing. For this purpose, a relatively small number of friction segments, namely four to eight, preferably six, are applied to each side of the carrier disc, which is preferably ring-shaped and made of sheet metal, for example, bonded to it. The friction segments are made of friction material, for example, paper.

[0011] For the purposes of the invention, "paper" is understood to mean fibrous material, for example containing at least some aramid fibers, with optionally added additives, for example to increase the coefficient of friction, elasticity, temperature resistance, and / or the like, which is, for example, suspended in a pulp and steam-pressed into semi-finished products such as sheets, rolls, or the like. The friction segments may be die-cut from the semi-finished product.

[0012] Reducing the number of friction segments allows for two advantages: firstly, the positioning and application of the friction segments to the carrier disc, and thus the assembly effort and costs, can be reduced; secondly, the larger extension angle of the individual friction segments, for example from 45° to 90°, preferably 60°, allows for an improved design of the friction surface structures on the friction surface of the friction segments, specifically aimed at reducing drag torques when the multi-plate clutch is opening or open. Furthermore, preferably, axially formed first indentations are provided on both sides at the circumferential ends, with the friction segments being spaced apart from each other circumferentially by radial gaps.The radial gaps serve to allow fluid to flow in and cool the clutch pack, with the inflow and outflow of fluid being supported by the first indentations, so that, especially when the clutch plate opens, the fluid flows away quickly and the drag torques caused by it are minimized.

[0013] It has proven advantageous if at least the axial projection of the associated lamella carrier, which holds the friction lamellae in a rotationally fixed manner, has openings at least on a portion of the circumference of the radial gaps. The fluid is supplied and discharged through these openings.

[0014] The problem is also solved by a friction plate for the proposed multi-plate clutch, in which a carrier disc contains friction segments arranged on both sides, wherein four to eight, preferably six, friction segments are distributed around the circumference, each with axially formed first indentations at its circumferential ends, and the friction segments are spaced apart from each other circumferentially by radial gaps. This combination of features allows for cost-effective manufacturing and drag torque optimization of friction plates, since, on the one hand, a small number of components need to be processed, and on the other hand, the wide extension angle allows for indentations, particularly at the circumferential ends, that can extend over a wide angle in the circumferential direction. Compared to a single-piece, ring-shaped friction segment, this design offers the possibility of providing sufficiently dimensioned radial gaps between the individual friction segments.Furthermore, significant material savings are possible because a die-cutting cutout within a ring-shaped friction segment is eliminated. Instead, the friction segments can be arranged almost seamlessly and with minimal material usage along a sheet, strip, or roll-shaped semi-finished product. The embossing can be incorporated, for example, during the production of the paper as a semi-finished product using a hot-pressing process, by employing a suitably profiled press roller or press plate. After the semi-finished product has cooled, the friction segments can then be cut out, punched, or separated in a similar manner.

[0015] According to an advantageous embodiment of the proposed friction plate, at least one second indentation can be provided in the friction segments between the first circumferential indentations. Preferably, two second indentations are provided per friction segment, resulting in three axially raised friction areas. The radial transitions between the friction areas and the indentations can be formed precisely on the diameter through the axis of rotation, creating trapezoidal friction areas, or they can form an angle of attack relative to the diameter, resulting in geometrically identical or different friction areas. When the multi-plate clutch engages, the friction areas first come into contact with the friction surfaces of the counter plates. The indentations allow fluid flow to dissipate frictional heat, particularly during clutch slippage, and to prevent uncontrolled adhesion of the friction segments to the counter plate, which would increase the drag torque.

[0016] Depending on the design of the axial elasticity of the friction segments and / or the actuating force of the multi-plate clutch applied to the plate pack, the friction areas can be reversibly deformed axially when the multi-plate clutch is closed, so that the indentations also contribute at least a small amount to friction when the multi-plate clutch is completely closed, exhibiting only slight or no slippage, and thus increase the maximum torque that can be transmitted via the multi-plate clutch.

[0017] The surface area of ​​the indentations, including the radial gap, can be greater than 40%, preferably greater than 50%, of the total area of ​​the friction segments. The circumferential extent of the first indentation can be 1 to 5 times, preferably 1 to 2 times, the circumferential width of the radial gap. This means that, even with a reduced thickness of the first indentations compared to the radial gaps, the volume required to allow fluid flow is at least equal to or greater due to the circumferential proximity of two first indentations on two friction segments. For example, with a friction segment thickness of 0.5 mm to 0.7 mm, preferably 0.6 mm, the groove depth of the indentations is 0.2 mm to 0.3 mm, i.e., approximately half the thickness. It is understood that with other thicknesses of the friction segments, the groove depth can also be different, for example, half the thickness or less.

[0018] The friction lamella can be shortened radially outwards in the circumferential direction, for example by having chamfers on the first indentations. This creates a radially outward chamfer that, for example, forms an inlet or outlet funnel for the fluid. These chamfers, preferably arranged on both sides of a friction segment, are advantageous for saving on lining material such as paper for forming the friction segments, since the friction segments become narrower overall without losing significant friction surface area. A phase angle with respect to the diameter of the circumferential ends of the friction segment can, for example, be between 20° and 40°.

[0019] The carrier disc of the friction plate can be made of metal, plastic, in particular fiber-reinforced plastic, ceramic, composite material, and / or similar material. According to an advantageous embodiment of the friction plate, the carrier disc is made of spring steel and has a corrugated surface around its circumference. Depending on the number of corrugations or vertices, predetermined portions of the friction segments, preferably the friction areas, engage with the counter plates first when the clutch is closing, and predetermined portions of the friction segments lift off first when the clutch is opening, so that the friction engagement and thus the drag torque can be defined more precisely. The axial amplitude of the corrugations can be, for example, in the range of the thickness of the indentations or less. The number of corrugations can be approximately equal to the number of friction segments around the circumference of the friction plate up to the number of indentations around the circumference of the friction plate.

[0020] The invention is explained in more detail with reference to the embodiments shown in Figures 1 to 6. These show:

[0021] Figure 1 shows a section of the upper part of a multi-plate clutch arranged to rotate about an axis of rotation; Figure 2 shows a view of a friction plate of the multi-plate clutch of Figure 1.

[0022] Figure 3 is a 3D model of the friction lamella of Figure 2.

[0023] Figure 4 shows a detailed view of the friction lamella of Figures 2 and 3 in the area of ​​the first impressions.

[0024] Figure 5 shows a section through the detail of Figure 4 and

[0025] Figure 6 shows a longitudinal section through the friction lamella of Figures 2 and 3.

[0026] Figure 1 shows a section of the upper part of the multi-plate clutch 1, which is rotatably arranged about the axis of rotation d, showing the two plate carriers 2, 3, which receive the plate pack 6 on the radially superimposed axial projections 4, 5. The plate pack 6 is formed from the friction plates 7, which are alternately stacked in the axial direction and rotatably suspended in the projection 4, and the counter plates 8, which are rotatably suspended in the projection 5.

[0027] To actuate the multi-plate clutch 1, the actuating lever 9, which is axially actuated by an actuating unit, axially pre-tensions the multi-plate pack 6 against the stop 10, so that a frictional connection is formed between the friction plates 7 and the counter plates 8.

[0028] The friction plates 7 have annular carrier discs 11 on which friction segments 12 are arranged on both sides around the circumference, the section along a radial gap separating the friction segments from each other in the circumferential direction being shown. The friction segments 12 each have indentations 13 at their circumferential ends facing the counter plates 8, which improve the free passage of fluid flowing through the plate assembly, wherein radially opposite openings 14, like passage openings, are provided in the projection 4 opposite the radial gaps and first indentations 13.

[0029] Figures 2 and 3 show one of the friction plates 7 arranged around the axis of rotation d of Figure 2 in a horizontal and a 3D view. In the illustrated embodiment of the friction plate 7, six friction segments 12 with a circumferential angle slightly less than 60° are arranged on each side, distributed around the circumference. As shown, the friction segments 12 are arranged in phase on both sides of the carrier disk 11, meaning that the radial gaps 15 separating the friction segments 12 circumferentially are located at the same circumferences. In further embodiments, the friction segments 12 on one side of the carrier disk 11 can have a circumferential angle relative to the friction segments 12 on the other side.

[0030] The friction segments 12 are arranged outside the toothing 16 for the rotationally fixed mounting of the friction plate 7 on the plate carrier 2. The toothing 16 comprises a multiple of teeth 17 compared to the number of friction segments 12 – in this case, a factor of three.

[0031] The friction segments 12 have circumferential indentations 13 that enlarge the passage space 19 with width B relative to the radial gaps 15 for fluid. Circumferentially, between the first indentations 13, two circumferentially spaced second indentations 18 are arranged, resulting in three axially raised friction areas 20 per friction segment 12. The dividing lines 21 between the indentations 13 and 18 have an angle of attack α relative to the diameter D1, forming trapezoidal friction areas 20 with a radially inner, narrower base. The dividing lines 21 of the first indentations 13 narrow the passage space 19 radially outward. Figure 4 shows detail D of the friction plate 7 of Figures 2 and 3 in a view in the area of ​​the radial groove 15 separating the two friction segments 12.The first indentations 13 and the radial groove 15 form the passage space 19 with width B, wherein the width a of each indentation 13 is at least one to two times the width b of the radial groove 15. The radial groove 15 has a width b of, for example, 2 mm. The radial groove 15 is arranged radially outside the tooth gap 22 of the toothing 16, so that the radial groove is located directly radially outside a passage opening of a tooth of the toothing of the lamellar carrier, which is complementary to this toothing 16 and receives the friction lamella 7. The friction segments 12, or the first indentations 13, have radially inner radii 23 and radially outer chamfers 24 that are enlarged accordingly.The chamfers 24 have a phase angle β between 20° and 40° relative to the diameter D of the friction plate 7 and thereby shorten the overall length of the friction segments 12, so that these can be manufactured in a material-saving manner by making the semi-finished product provided for them and their manufacturing tools narrower.

[0032] Figure 5 shows the friction plate 7 of Figures 2 and 3 as a section of detail D of Figure 4, including the carrier disc 11 and the friction segments 12 arranged on both sides. The first indentations 13, spaced apart circumferentially by the width b of the radial gap 15, are recessed relative to the friction areas 20 by the groove depth t. For example, the groove depth t is approximately half the thickness d1 of the friction segment 12. In the illustrated embodiment, the thickness d1 is approximately 0.6 mm and the groove depth is a maximum of 0.3 mm. Figure 6 shows the friction plate 7 of the preceding figures, arranged about the axis of rotation d, in longitudinal section with the friction segments 12 arranged on both sides. The carrier disc 11 has the corrugation 25 around its circumference, which is not shown to scale.The amplitude w of the corrugation 25, for example, is at most in the range of the thickness d2 of the friction plate 7 and preferably at most in the groove depth t (Figure 5) of the indentations 13, 18. The number of individual corrugations of the corrugation 25 can range from the number of friction segments to the number of friction areas 20. The corrugation, for example, causes the friction segments 12 to lift off the counter plates 8 quickly when the multi-plate clutch 1 opens, thus reducing drag torques.

[0033] List of reference signs

[0034] Multi-plate clutch, multi-plate carrier, multi-plate carrier, attachment, attachment, multi-plate pack, friction plate, counter plate, actuating lever, stop, carrier disc

[0035] 12 friction segments

[0036] 13. Imprint

[0037] 14 Opening

[0038] 15 radial gap

[0039] 16 gear teeth

[0040] 17 teeth

[0041] 18. Embossing

[0042] 19 Passageway

[0043] 20 friction area

[0044] 21 Dividing line

[0045] 22 tooth gaps

[0046] 23 Rounding

[0047] 24 Bevel

[0048] 25 wave a width

[0049] B width b width

[0050] D Detail

[0051] D1 diameter d axis of rotation d1 thickness d2 thickness t groove depth w amplitude a angle of attack ß angle of attack

Claims

Patent claims 1. Multi-plate clutch (1) for wet operation by means of a fluid, comprising a multi-plate pack (6) arranged about a rotational axis (d) of the multi-plate clutch (1) and axially loadable to form a frictional connection, consisting of alternately axially layered friction plates (7) and counter plates (8), wherein the friction plates (7) are rotationally connected to a first and the counter plates (8) to a second plate carrier (2, 3), and each plate carrier (2, 3) is assigned to an input part and the other plate carrier (2, 3) to an output part of the multi-plate clutch (1), wherein the friction plates (7) include a carrier disk (11) with friction segments (12) arranged on both sides, characterized in that four to eight are distributed around the circumference,preferably six friction segments (12) with axially formed first impressions (13) at their circumferential ends are provided and the first impressions 13 form an enlarged passage space (19) for the fluid by means of radial gaps (15) spaced apart from each other in the circumferential direction of the friction segments (12).

2. Lamellar coupling (1 ) according to claim 1 , characterized in that an axial projection (4) which receives the friction lamellae (7) in a rotationally fixed manner has openings (14) at least on at least a part of the circumferences of the radial gaps (15) of at least one of the lamella carriers (2).

3. Friction plate (7) for a multi-plate clutch (1 ) according to one of claims 1 or 2, characterized in that a carrier disk (11 ) contains friction segments (12) arranged on both sides, wherein four to eight, preferably six, friction segments (12) are provided distributed around the circumference with first embossings (13) axially formed at their circumferential ends and the first embossings 13 together with radial gaps (15) spaced apart from each other in the circumferential direction form an enlarged passage space (19) for the fluid.

4. Friction plate (7) according to claim 3, characterized in that at least a second embossing (18) is provided in the friction segments (12) between the first embossings (13) in the circumferential direction.

5. Friction plate (7) according to claim 4, characterized in that a surface area fraction of the imprints (13, 18) is greater than 40%, preferably greater than 50% of the total surface area of ​​the friction segments (12).

6. Friction plate (7) according to one of claims 3 to 5, characterized in that a width (a) of the first imprint corresponds to 1 to 5 times, preferably 1 to 2 times, the width (b) of the radial gap in the circumferential direction.

7. Friction plate (7) according to one of claims 3 to 6, characterized in that a groove depth (t) of the embossings (13, 18) is 0.2 mm to 0.3 mm.

8. Friction plate (7) according to one of claims 3 to 7, characterized in that the first imprints (13) have radially outward chamfers (24).

9. Friction plate (7) according to claim 8, characterized in that the chamfers (24) have a phase angle (β) between 20° and 40° to the diameter (D) of the circumferential ends of the friction segments (12).

10. Friction plate (7) according to one of claims 3 to 9, characterized in that the carrier disc (11 ) is made of spring steel and is corrugated over its circumference.

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