Friction clutch

Abstract

The present invention relates to a friction clutch (1) comprising a housing (2), a counter-pressure plate (6) secured to the housing, a pressure plate (4) which can be moved to a limited extent in the axial direction (A) of the friction clutch (1), multiple actuating devices (5), a spring mechanism (15) and a clutch disc (3), wherein, in an engaged state of the friction clutch (1), the clutch disc (3) is frictionally clamped between the counter-pressure plate (6) and the pressure plate (4) by a force generated by the spring mechanism (15), wherein, in a disengaged state of the friction clutch (1), the pressure plate (4) is separated from the clutch disc (3) via the actuating devices (5) against the force generated by the spring mechanism (15), wherein each of the actuating devices (5) has a respective actuating lever (9) and an intermediate lever (10), wherein an outer end (11) of the actuating lever (9) in the radial direction (R) of the friction clutch (1) is rotatably secured to the housing (2) via an actuating bearing (16), wherein the intermediate lever (10) has a radially (R) outer first end (13) and a radially (R) inner second end (14), wherein the intermediate lever (10) is rotatably secured to the actuating lever (9) via an intermediate bearing (17), and wherein the intermediate lever (10), at the first end (13), acts on the pressure plate (4) via a pressure lever (20) rotatably secured at the first end (13) by means of a pressure bearing (21), and, at the second end (14) is supported by the counter-pressure plate (20).

Description

[0001] Friction clutch

[0002] The present invention relates to a friction clutch, in particular for a motor vehicle, preferably a tractor clutch.

[0003] Dual-clutch transmissions for tractors are known in which one of the partial clutches consists of a friction surface on a housing, a friction surface on an axially movable pressure plate, and a clutch disc located between them. The pressure plate is subjected to a clamping force by a spring accumulator, for example, a disc spring. The direction of the clamping force is oriented such that the clutch disc is clamped between the friction surfaces of the pressure plate and the housing for torque transmission. To disengage this partial clutch, the pressure plate must be moved against the force exerted by the spring accumulator.

[0004] This typically involves the use of several actuating levers. Each actuating lever is mounted to the housing via a pivot joint and is driven at its tip by an actuating bearing. The actuating levers are connected to the pressure plate by a respective push lever, allowing the friction clutch to be disengaged via the actuating levers. When the force applied to the actuating bearing is reduced, the force from the spring accumulator presses the pressure plate against the clutch disc, thus engaging the friction clutch. The actuating levers and the actuating bearing are also moved back via the push levers.

[0005] When the partial clutch is not engaged, the tips of the actuating levers should lift off the actuating bearing. To achieve this, the actuating bearing is moved back sufficiently to create a gap between the tips of the actuating levers and the actuating bearing. This gap is intended to reduce wear and prevent vibrations. However, centrifugal forces or axial vibrations can cause the tips of the actuating levers to come into contact with the actuating bearing. To prevent this, it is known to preload the actuating levers with preload springs. The preload springs generate a force that moves the actuating levers towards the pressure plate. In other words, this force preloads the actuating levers in the direction of the disengagement movement. Thus, a constant gap between the tips of the actuating levers and the actuating bearing is ensured when the friction clutch is not engaged.Furthermore, due to the preload, the contact points of the actuating levers are permanently in contact with the pressure plate, so that no adverse joint play has to be overcome during an actuation movement.

[0006] This design, however, becomes problematic if there is a radial offset of the pressure plate within the housing. Such an offset can arise, for example, from play in the axial guide. The radial offset of the pressure plate causes an axial displacement of the actuating lever tips, which varies in intensity between individual actuating levers. This effect is known as tip flex. When the actuating bearing is moved, this does not result in a uniform movement of the actuating levers. This negatively affects the movement of the pressure plate and can lead to undesirable clutch characteristics, such as uncomfortable disengagement of the friction clutch.

[0007] Approaches to solving this problem are known from DE 23 57 860 C2 and DE 31 42 107 A1. These approaches use intermediate levers mounted on the actuating lever via a pivot joint. This prevents any radial displacement of the pressure plate within the housing from affecting the lever positions. A preload spring must also be used for these arrangements with an intermediate lever. When the force generated by the preload spring acts on the actuating lever, the required function—namely, securing the components against the pivot points—is fulfilled.

[0008] A disadvantage of the preload spring's placement on the actuating lever is that it follows the entire range of motion. This range consists of the disengagement travel and any additional wear travel. This means that during operation, an oscillation and, due to the wear range, further displacement can occur during the engagement and disengagement movements. The spring's operating range must be dimensioned accordingly and is therefore considerably large. Consequently, the spring must be designed accordingly, and a significant change occurs between the required minimum spring force and the maximum spring force. Since the force generated by the preload spring opposes the force generated by the spring accumulator, functional disadvantages arise for the friction clutch as a whole. The usable contact force of the clutch disc against the friction surfaces is reduced, thereby decreasing torque transmission.Furthermore, the contact force changes due to wear over the operating period.

[0009] The object of the present invention is to provide a reliable, robust, and cost-effective friction clutch. In particular, it aims to prevent any disruptive feedback on the actuating lever positions, especially in the form of a crease, when the pressure plate is radially misaligned in the housing.

[0010] According to the invention, this problem is solved by a friction clutch according to claim 1 comprising a housing, a housing-fixed counter-pressure plate, a pressure plate that is axially displaceable within limits in the friction clutch, several actuating devices, a spring accumulator, and a clutch disc, wherein in an engaged state of the friction clutch, the clutch disc is frictionally clamped between the counter-pressure plate and the pressure plate by a force generated by the spring accumulator, wherein in a disengaged state of the friction clutch, the pressure plate is separated from the clutch disc by the actuating devices against the force generated by the spring accumulator, wherein each of the actuating devices comprises an actuating lever and an intermediate lever, wherein an outer end of the actuating lever in the radial direction of the friction clutch is rotatably attached to the housing via an actuating bearing.wherein the intermediate lever has a radially outer first end and a radially inner second end, wherein the intermediate lever is rotatably attached to the actuating lever via an intermediate bearing.

[0011] Since the intermediate lever acts on the pressure plate at the first end via a pressure lever which is rotatably attached to the first end by means of a thrust bearing and is supported at the second end by the counter-pressure plate, the friction clutch can on the one hand prevent or reduce a cupping shock and on the other hand still be permanently functionally reliable.

[0012] Preferred embodiments of the friction clutch according to the invention are set out in the dependent claims.

[0013] Preferably, the thrust bearing is arranged further outwards in the radial direction than the intermediate bearing. This allows the friction clutch to be designed for long-term reliable operation.

[0014] Furthermore, the thrust bearing is preferably arranged closer to the pressure plate in the axial direction than the intermediate bearing. This allows the friction clutch to be designed with long-term reliability.

[0015] Furthermore, the thrust bearing is preferably arranged closer to the pressure plate in the axial direction than the actuating bearing. This allows the friction clutch to be designed with long-term functional reliability.

[0016] It is advantageous if the second end of the intermediate lever is supported directly against the counter-pressure plate. This ensures that the friction clutch functions reliably over the long term.

[0017] Alternatively, it is advantageous if the second end of the intermediate lever is indirectly supported on the counter-pressure plate, preferably via a wire ring or a ramp ring of a wear adjustment device. This allows the friction clutch to be designed for long-term reliable operation.

[0018] It is also advantageous if the actuating lever has two actuating lever sections spaced apart from each other in the circumferential direction of the friction clutch and extending radially, between which the intermediate lever is arranged and extends radially. This allows the friction clutch to be designed with long-term functional reliability. Preferably, the pressure lever is fork-shaped and has two prong sections between which the intermediate lever is arranged and rotatably connected to the pressure lever via the thrust bearing. This allows the friction clutch to be designed with long-term functional reliability.

[0019] It is advantageous if each of the actuating devices has a preload spring that pre-tensions the actuating lever and / or the intermediate lever by acting on the actuating lever and / or the intermediate lever. This ensures that the friction clutch functions reliably over the long term.

[0020] Furthermore, it is advantageous if the end of the pressure lever facing the pressure plate has a recess into which an adjusting bolt on the pressure plate side engages, with the engagement being maintained by preload of the spring accumulator and / or the respective preload spring. This ensures that the friction clutch can be designed to function reliably over the long term.

[0021] The present invention is explained in more detail below with reference to preferred embodiments in conjunction with the accompanying figures. These show:

[0022] Figure 1: a sectional view of an embodiment of a friction clutch with an actuating lever, an intermediate lever and a pressure lever,

[0023] Figure 2: a perspective view of an assembly of actuating lever, intermediate lever and pressure lever from Figure 1 ,

[0024] Figure 3a: a sectional view of the assembly of the actuating lever, intermediate lever and pressure lever from Figure 2 through a first sectioning plane,

[0025] Figure 3b: a sectional view of the assembly of the actuating lever, intermediate lever and pressure lever from Figure 2 through a second sectioning plane; Figure 4a: a schematic sectional view of the friction clutch from Figure 1 with a centrally arranged pressure plate; and

[0026] Figure 4b: a schematic sectional view of the friction clutch from Figure 1 with an eccentrically arranged pressure plate shifted to the right.

[0027] Figure 1 shows a sectional view of an embodiment of a friction clutch 1 with an actuating lever 9, an intermediate lever 10, and a pressure lever 20. In the illustrated embodiment, the assembly of the actuating lever 9, the intermediate lever 10, and the pressure lever 20 forms an actuating device 5 of the friction clutch 1.

[0028] The friction clutch 1 is preferably designed as a normally engaged friction clutch, i.e., engaged in the free-of-acting state, and is in particular a tractor clutch, preferably a partial clutch of a tractor double clutch. The friction clutch 1 is rotatable about an axis of rotation D and has a housing 2. A pressure plate 4, which is displaceable within limits in the axial direction A of the friction clutch 1, is arranged in the housing 2. Furthermore, a counter-pressure plate 6, which is fixed in the axial direction A, i.e., fixed to the housing, is arranged in the housing 2 and may preferably be formed integrally with the housing 2.

[0029] The friction clutch 1 further comprises several actuating devices 5 distributed around its circumference U, a spring accumulator 15, and a clutch disc 3. In an engaged state, the clutch disc 3 is frictionally clamped between the counter-pressure plate 6, more precisely between a friction surface 7 of the counter-pressure plate 6, and the pressure plate 4, more precisely between a friction surface 8 of the pressure plate 4, by a force generated by the spring accumulator 15. The spring accumulator 15 acts directly or indirectly on the pressure plate 4, which is axially displaceable within limits in the direction A, in the form of coil springs, leaf springs, or a disc spring. In a disengaged state, the frictional engagement described above between the clutch disc 3 and the pressure plate 4, as well as between the clutch disc 3 and the counter-pressure plate 6, is eliminated.The pressure plate 4 is separated from the clutch disc 3 against the force generated by the spring accumulator 15 via the actuating devices 5. For example, the actuating devices 5 can act on the pressure plate 4 via their pressure levers 20, which are distributed in the circumferential direction U and can be displaced in the axial direction A, in order to move the pressure plate 4 away from the counter-pressure plate 6 in the axial direction A, i.e., to press it downwards with reference to Figure 1.

[0030] Each of the actuating devices 5 has an actuating lever 9, an intermediate lever 10, and a pressure lever 10, which are shown in their assembly in Figures 2, 3a, and 3b. Furthermore, each of the actuating devices 5 can have a preload spring 27, indicated in Figure 1, by which the actuating lever 9 and / or the intermediate lever 10 is / are preloaded by the preload spring 27 acting on the actuating lever 9 and / or the intermediate lever 10 on one side, and supported on the housing 2 and / or the counter-pressure plate 6 on the other. Preferably, the preload spring 27 is designed as a torsion spring or as a helical spring.

[0031] An outer end 11 of the actuating lever 9, located in the radial direction R of the friction clutch 1, is rotatably attached to the housing 2 via an actuating bearing 16. An inner end 12 of the actuating lever 9, located in the radial direction R, has an actuating dome that can be brought into contact with a release bearing of a release device that is displaceable in the axial direction A.

[0032] As shown structurally in Figures 1 to 3b and schematically in Figures 4a and 4b, the intermediate lever 10 has a first end 13 located radially outside in the direction R and a second end 14 located radially inside in the direction R. The intermediate lever 10 acts at its first end 13 on the pressure lever 20, which is rotatably attached to the first end 13 by means of a thrust bearing 21. "Rotatably attached" in this context means that the rotatable thrust bearing 21 can transmit both tensile and compressive forces to the pressure lever 20 and from the pressure lever 20 to the intermediate lever 10.

[0033] Furthermore, the intermediate lever 10 is supported directly or indirectly at its second end 14 on the counter-pressure plate 6, more precisely on a rear surface 22 of the counter-pressure plate 6. Figure 1 shows indirect support by a ramp ring 24 of a wear adjustment device 25. Indirect support is also possible, for example, via a friction-reducing wire ring. Direct support in the form of the intermediate lever 10 directly contacting the rear surface 22 of the counter-pressure plate 6 is also possible. The rear surface 22 of the counter-pressure plate 6 is formed in the axial direction A on the side opposite the friction surface 7 of the counter-pressure plate 6, i.e., on the side of the counter-pressure plate 6 facing away from the clutch disc 3.

[0034] The intermediate lever 10 is rotatably attached to the actuating lever 9 via an intermediate bearing 17, which is arranged between the first end 13 and the second end 14 of the intermediate lever 10. Thus, a first lever section 18 of the intermediate lever 10 extends radially in direction R between the intermediate bearing 17 and the first end 13, while a second lever section 19 of the intermediate lever 10 extends radially in direction R between the intermediate bearing 17 and the second end 14. The aforementioned preload spring 27 preferably engages the housing 2 on one side and the intermediate lever 10 on the other side between the intermediate bearing 17 and the second end 14, i.e., in the second lever section 19.

[0035] The actuating bearing 16 is located further in axial direction A than the first lever section 18 of the intermediate lever 10 from the pressure plate 4. That is, the first lever section 18 of the intermediate lever 10 is arranged in axial direction A between the actuating bearing 16 and the pressure plate 4.

[0036] Furthermore, the actuating bearing 16 is arranged further outwards in the radial direction R than the intermediate bearing 17. The thrust bearing 21 is also arranged further outwards in the radial direction R than the intermediate bearing 17. In the axial direction A, the thrust bearing 17 is arranged closer to the clutch disc 3 or the pressure plate 4 than the intermediate bearing 17. Likewise, in the axial direction A, the thrust bearing 21 is arranged closer to the clutch disc 3 or the pressure plate 4 than the actuating bearing 16.

[0037] As shown in Figure 2, the actuating lever 9 preferably has two actuating lever sections 23, spaced apart from each other in the circumferential direction U or, with respect to the axis of rotation D, in the transverse direction of the friction clutch 1, and extending in the radial direction R, between which the intermediate lever 10 is arranged and extends in the radial direction R. While the actuating lever sections 23 are designed as separate components in the illustrated embodiment, it is also possible for the actuating lever 9 to be designed as a single piece (e.g., with a U-shaped cross-section), so that the actuating lever sections 23 are designed as component sections of the same single-piece actuating lever 9.

[0038] The pressure lever 20 is fork-shaped and has two prong sections 26. Between the prong sections 26 and the intermediate lever 10, more precisely at the first end 13 of the intermediate lever 10, the pressure bearing 21 is formed, via which the intermediate lever 10 is rotatably connected to the pressure lever 20.

[0039] An end 28 of the pressure lever 20 facing the pressure plate 4 has a recess 29 into which an adjusting bolt 30 on the pressure plate side engages. The recess 29 is, for example, designed as a blind hole. The clearance of the pressure plate 4 can be adjusted via the adjusting bolt 30. The adjusting bolt 30 has only loose contact with the end 28 of the pressure lever 20 or with the recess 29, in particular to hold the pressure lever 20 in position relative to the pressure plate 4, so that the engagement is maintained by the preload of the spring accumulator 15 and / or the respective preload spring 27.

[0040] From the schematic representations in Figures 4a (friction clutch 1 from Figure 1 with centrally arranged pressure plate 4) and 4b (friction clutch 1 from Figure 1 with eccentrically arranged pressure plate 4 shifted to the right), it can be seen that with radial offset of the pressure plate 4 in the housing 2, only lower forces are to be expected at the joint points due to the small angles of the pressure levers 20. Furthermore, with radial offset of the pressure plate 4 in the housing 2, there is no or only a negligible effect on the crest height of the actuating levers 9 in axial direction A, i.e., the crest impact is minimal.

[0041] The preceding embodiments relate to a friction clutch 1 with a housing 2, a housing-fixed counter-pressure plate 6, a pressure plate 4 which is axially displaceable to a limited extent in direction A of the friction clutch 1, several actuating devices 5, a spring accumulator 15 and a clutch disc 3, wherein in an engaged state of the friction clutch 1 the clutch disc 3 is frictionally clamped between the counter-pressure plate 6 and the pressure plate 4 by a force generated by the spring accumulator 15, wherein in a disengaged state of the friction clutch 1 the pressure plate 4 is separated from the clutch disc 3 by the actuating devices 5 against the force generated by the spring accumulator 15, wherein each of the actuating devices 5 has an actuating lever 9 and an intermediate lever 10.wherein an outer end 11 of the actuating lever 9 in the radial direction R of the friction clutch 1 is rotatably attached to the housing 2 via an actuating bearing 16, wherein the intermediate lever 10 has a first end 13 that is outer in the radial direction R and a second end 14 that is inner in the radial direction R, wherein the intermediate lever 10 is rotatably attached to the actuating lever 9 via an intermediate bearing 17, and wherein the intermediate lever 10 acts on the pressure plate 4 at its first end 13 via a pressure lever 20 which is rotatably attached to the first end 13 by means of a thrust bearing 21, and is supported at its second end 14 via the counter-pressure plate 6.

[0042] List of reference signs

[0043] 1 friction clutch

[0044] 2 cases

[0045] 3 Clutch disc

[0046] 4 pressure plate

[0047] 5 Actuating device

[0048] 6 Counter-pressure plate

[0049] 7 Friction surface of the counter-pressure plate

[0050] 8 Friction surface of the pressure plate

[0051] 9 operating levers

[0052] 10 intermediate levers

[0053] 11 outer end of the actuating lever in radial direction

[0054] 12 in radial direction inner end of the actuating lever

[0055] 13 first end of the intermediate lever

[0056] 14 second end of the intermediate lever

[0057] 15 spring storage units

[0058] 16 actuating bearings

[0059] 17 interim storage facilities

[0060] 18 First lever section of the intermediate lever

[0061] 19 second lever section of the intermediate lever

[0062] 20 pressure levers

[0063] 21 thrust bearings

[0064] 22 Back of the counter-pressure plate

[0065] 23 Actuating lever section

[0066] 24 Ramp Ring

[0067] 25 Wear adjustment device

[0068] 26 tine section

[0069] 27 Preload spring

[0070] 28 End of the pressure lever facing the pressure plate

[0071] 29 recess

[0072] 30 adjusting bolts

[0073] A axial direction D axis of rotation

[0074] R radial direction

[0075] U circumferential direction

Claims

Patent claims 1. Friction clutch (1) comprising a housing (2), a housing-fixed counter-pressure plate (6), a pressure plate (4) which is axially displaceable (A) of the friction clutch (1), several actuating devices (5), a spring accumulator (15) and a clutch disc (3), wherein in an engaged state of the friction clutch (1) the clutch disc (3) is frictionally clamped between the counter-pressure plate (6) and the pressure plate (4) by a force generated by the spring accumulator (15), wherein in a disengaged state of the friction clutch (1) the pressure plate (4) is separated from the clutch disc (3) via the actuating devices (5) against the force generated by the spring accumulator (15), wherein each of the actuating devices (5) comprises an actuating lever (9) and an intermediate lever (10),wherein an outer end (11) of the actuating lever (9) in the radial direction (R) of the friction clutch (1) is rotatably attached to the housing (2) via an actuating bearing (16), wherein the intermediate lever (10) has a first end (13) that is outer in the radial direction (R) and a second end (14) that is inner in the radial direction (R), wherein the intermediate lever (10) is rotatably attached to the actuating lever (9) via an intermediate bearing (17), and wherein the intermediate lever (10) acts on the pressure plate (4) at its first end (13) via a pressure lever (20) rotatably attached to the first end (13) by means of a thrust bearing (21) and is supported at its second end (14) via the counter-pressure plate (6).

2. Friction clutch (1 ) according to claim 1 , wherein the thrust bearing (21 ) is arranged further outwards in the radial direction (R) than the intermediate bearing (17).

3. Friction clutch (1 ) according to claim 1 or 2, wherein the thrust bearing (21 ) is arranged closer to the pressure plate (4) in the axial direction (A) than the intermediate bearing (17).

4. Friction clutch (1 ) according to one of claims 1 to 3, wherein the thrust bearing (21 ) is arranged closer to the pressure plate (4) in the axial direction (A) than the actuating bearing (16).

5. Friction clutch (1 ) according to one of claims 1 to 4, wherein the second end (14) of the intermediate lever (10) is directly supported on the counter pressure plate (6).

6. Friction clutch (1 ) according to one of claims 1 to 4, wherein the second end (14) of the intermediate lever (10) is indirectly supported on the counter-pressure plate (6), preferably via a wire ring or a ramp ring (24) of a wear adjustment device (25).

7. Friction clutch (1 ) according to one of claims 1 to 6, wherein the actuating lever (9) has two actuating lever sections (23) spaced apart in the circumferential direction (U) of the friction clutch (1 ) and extending in the radial direction (R), between which the intermediate lever (10) is arranged and extends in the radial direction (R).

8. Friction clutch (1 ) according to one of claims 1 to 7, wherein the pressure lever (20) is fork-shaped and has two prong sections (26) between which the intermediate lever (10) is arranged and rotatably connected to the pressure lever (20) via the thrust bearing (21 ).

9. Friction clutch (1 ) according to one of claims 1 to 8, wherein each of the actuating devices (5) has a preload spring (27) by which the actuating lever (9) and / or the intermediate lever (10) is / are preloaded by the preload spring (27) acting on the actuating lever (9) and / or on the intermediate lever (10).

10. Friction clutch (1 ) according to one of claims 1 to 9, wherein an end (28) of the pressure lever (20) facing the pressure plate (4) has a recess (29) into which a pressure plate-side adjusting bolt (30) engages, wherein the engagement is maintained by preload of the spring accumulator (15) and / or the respective preload spring (27).

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