Friction clutch

Abstract

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) outer in the radial direction (R) and a second end (14) inner in the radial direction (R), wherein the intermediate lever (10) is rotatably attached to the actuating lever (9) via an intermediate bearing (17), wherein the intermediate lever (10) acts on the pressure plate (4) at its first end (13) and is supported at its second end (14) by the counter-pressure plate (6), and wherein a friction-reducing device (21) is arranged between the second end (14) of the intermediate lever (10) and the counter-pressure plate (6).

Description

[0001] The present invention relates to a friction clutch, in particular for a motor vehicle, preferably a tractor clutch.

[0002] Dual-clutch 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 positioned 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.

[0003] 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.

[0004] When the partial clutch is not actuated, the tips of the actuating levers should lift off the actuating bearing. For this purpose, 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, the actuating levers are preloaded by this force in the direction of the disengagement movement. This ensures a constant gap between the tips of the actuating levers and the actuating bearing.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.

[0005] 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.

[0006] 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.

[0007] A disadvantage of the preload spring's position 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.

[0008] 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.

[0009] 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 against the force generated by the spring accumulator via the actuating devices, 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, and wherein the intermediate lever acts on the pressure plate at its first end and is supported at its second end by the counter-pressure plate.

[0010] Since a friction-reducing device is arranged between the second end of the intermediate lever and the counter-pressure plate, the friction clutch can, on the one hand, prevent a crease and, on the other hand, still be permanently functionally reliable.

[0011] Preferred embodiments of the friction clutch according to the invention are set out in the dependent claims.

[0012] Preferably, each of the actuating devices has a preload spring by which the actuating lever and / or the intermediate lever is / are preloaded by the preload spring acting on the actuating lever and / or the intermediate lever. This enables a compact and robust design of the friction clutch.

[0013] Preferably, the preload spring engages the housing on one side and the intermediate lever between the intermediate bearing and the second end of the intermediate lever on the other. This allows for a compact and robust design of the friction clutch.

[0014] Furthermore, the preload spring is preferably a torsion spring. This allows for a compact and robust design of the friction clutch.

[0015] It is advantageous if the second end of the intermediate lever is in direct contact with the counter-pressure plate, and the friction-reducing device is designed as a surface modification, preferably as a coating increasing surface hardness and / or as a surface roughness-reducing surface treatment, of the second end of the intermediate lever and / or the contact area on a rear side of the counter-pressure plate, thereby enabling a robust design of the friction clutch.

[0016] Furthermore, it is advantageous if the second end of the intermediate lever is designed as a flattened, rounded lever tip, which enables a robust construction of the friction clutch.

[0017] It is also advantageous if the friction-reducing device is designed as a sheet metal strip, preferably ring-shaped or ring-segment shaped, which rests against a rear side of the counter-pressure plate and against which the second end of the intermediate lever rests, thereby enabling a robust construction of the friction clutch.

[0018] Furthermore, it is advantageous if the friction-reducing device is designed as a wire ring or wire ring section that is arranged between the second end of the intermediate lever and a rear side of the counter-pressure plate, thereby enabling a robust construction of the friction clutch.

[0019] It is also advantageous if the wire ring section is recessed, preferably pressed into, the second end of the intermediate lever, thus enabling a robust construction of the friction clutch.

[0020] It is also advantageous if the wire ring or wire ring section is recessed into a groove on the back of the counter-pressure plate, which enables a robust construction of the friction clutch.

[0021] Furthermore, it is advantageous if the friction-reducing device is designed as an additional coupling element, via which the second end of the intermediate lever is articulated to a rear side of the counter-pressure plate, preferably attached to a rear side of the counter-pressure plate, thereby enabling a robust construction of the friction clutch.

[0022] Preferably, the housing and the counter-pressure plate are formed as a single piece. This allows for a compact design of the friction clutch.

[0023] The present invention is explained in more detail below with reference to preferred embodiments in conjunction with the accompanying figures. These show: Fig. 1: A first embodiment of a friction clutch with an actuating lever and an intermediate lever, Fig. 2: a schematic representation of the friction clutch made of Fig. 1, Fig. 3: the second embodiment of a friction clutch with an actuating lever and an intermediate lever, Fig. 4: a schematic representation of the friction clutch made of Fig. 3, Fig. 5: a housing of a third embodiment of a friction clutch, Fig. 6: an intermediate lever of a fourth embodiment of a friction clutch, Fig. 7: a schematic representation of a fifth embodiment of a friction clutch, and Fig. 8: a schematic representation of a sixth embodiment of a friction clutch.

[0024] The Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. Figure 8 relates to six embodiments of a friction clutch 1, some of which can be combined. The clutch is, in particular, a tractor clutch, preferably a partial clutch of a tractor double clutch. The same reference numerals in the figures refer to the same features. The basic structure of the friction clutch 1, common to all embodiments, is explained with reference to the first embodiment, and the subsequent embodiments only address the differences from the first embodiment.

[0025] 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.

[0026] The friction clutch 1 further comprises several actuating devices 5 distributed around its circumference, a spring accumulator 15, and a clutch disc 3. In an engaged state of the friction clutch 1, the clutch disc 3 is frictionally clamped by a force generated by the spring accumulator 15 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. The spring accumulator 15 acts, in the form of coil springs, leaf springs, or a disc spring, directly or indirectly on the pressure plate 4, which is displaceable in the axial direction A.

[0027] In a disengaged state of the friction clutch 1, 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 suspended. 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 circumferentially distributed push rods 20, which are axially displaceable in direction A, in order to move the pressure plate 4 away from the counter-pressure plate 6 in the axial direction A.

[0028] Each of the actuating devices 5 has an actuating lever 9 and an intermediate lever 10. Furthermore, each of the actuating devices 5 can have one in the Fig. 1 and Fig. The three components have a preload spring, indicated by a preload spring, by which the actuating lever 9 and / or the intermediate lever 10 is / are preloaded, by the preload spring 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 is designed as a torsion spring or as a helical spring.

[0029] 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.

[0030] 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 on the pressure plate 4 at its first end 13, preferably via a first lever tip which is in contact with the push rod 20. Furthermore, the intermediate lever 10 is supported at its second end 14, preferably via a second lever tip 23, by the counter-pressure plate 6, more precisely by a rear surface 22 of the counter-pressure plate 6. 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.

[0031] 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 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.

[0032] 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.

[0033] Furthermore, the actuating bearing 16 is arranged further outwards in the radial direction R than the intermediate bearing 17. Furthermore, the first end 13 of the intermediate lever 10, more precisely the first lever tip, is arranged further inwards in the radial direction R than the actuating bearing 16 and further outwards in the radial direction R than the intermediate bearing 17.

[0034] Furthermore, all embodiments of the friction clutch 1 have in common that between the second end 14 of the intermediate lever 10, which is preferably located in the Fig. 1 and Fig. 2 is designed as a second lever tip 23, and a friction-reducing device 21 is arranged on the counter-pressure plate 6, more precisely on the back side 22 of the counter-pressure plate 6. The second lever tip 23 can preferably be designed as a flattened, rounded lever tip, whereupon with reference to Fig. Section 6 will be discussed in more detail.

[0035] The friction-reducing device 21 in the Fig. 1 and Fig. 2 is designed as a sheet metal strip 24, preferably ring-shaped or ring-segment-shaped, which abuts the rear side 22 of the counter-pressure plate 6, and against which the second end 14 of the intermediate lever 10 abuts. The sheet metal strip 24 may be provided with an increased surface hardness and / or a reduced surface roughness compared to the rear side 22 of the counter-pressure plate 6.

[0036] The friction-reducing device 21 in the Fig. 3 and Fig. 4 is designed as a wire ring section 26, which is arranged between the second end 14 of the intermediate lever 10 and the rear surface 22 of the counter-pressure plate 6. More precisely, a wire ring section 26 is embedded, preferably pressed into, the second end 14 of each intermediate lever 10. The wire ring section 26 can have a round or oval, optionally flattened, cross-section. Furthermore, the wire ring section 26 can be provided with increased surface hardness and / or reduced surface roughness compared to the rear surface 22 of the counter-pressure plate 6.

[0037] In Fig. Figure 5 shows only a housing 2 of a third embodiment of the friction clutch 1. The friction-reducing device 21 is designed as a wire ring 25 or as wire ring sections 26, which is / are arranged between the second ends 14 of the intermediate levers 10 and the rear surface 22 of the counter-pressure plate 6. More precisely, the wire ring 25 or the wire ring sections 26 are inserted into a groove 27 on the rear surface 22 of the counter-pressure plate 6. The wire ring 25 or the wire ring sections 26 can have a round or oval, optionally flattened, cross-section. Furthermore, the wire ring 25 or the wire ring sections 26 can be provided with an increased surface hardness and / or a reduced surface roughness compared to the rear surface 22 of the counter-pressure plate 6.

[0038] In Fig. Figure 6 shows only an intermediate lever 10 of a fourth embodiment of the friction clutch 1. At the second end 14 of the intermediate lever 10, the second lever tip 23 is designed as a flattened, rounded lever tip. In the edge region of the second lever tip 23, the radius is smaller than in the central region of the second lever tip 23, i.e., the curvature is greater in the edge region than in the central region. Furthermore, the second lever tip 23 can be provided with an increased surface hardness and / or a reduced surface roughness compared to the rear side 22 of the counter-pressure plate 6.

[0039] The friction-reducing device 21 in Fig. 7 is designed as a further coupling element 28, via which the second end 14 of the intermediate lever 10 is pivotally connected to the rear side 22 of the counter-pressure plate 6, preferably attached to the rear side 22 of the counter-pressure plate 6.

[0040] The friction-reducing device 21 in Fig.8 is designed as a surface modification both on the second lever tip 23 and on the back 22 of the counter-pressure plate 6, preferably as a coating increasing surface hardness and / or as a surface treatment reducing surface roughness.

[0041] The preceding embodiments show a friction clutch 1 with a housing 2, a housing-fixed counter-pressure plate 6, a pressure plate 4 which is axially displaceable within a limited range 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, wherein the intermediate lever 10 acts on the pressure plate 4 at its first end 13 and is supported at its second end 14 by the counter-pressure plate 6, and wherein a friction-reducing device 21 is arranged between the second end 14 of the intermediate lever 10 and the counter-pressure plate 6. Reference symbol list 1 friction clutch 2 cases 3 Clutch disc 4 pressure plate 5 Actuating device 6 Counter-pressure plate 7 Friction surface of the counter-pressure plate 8 Friction surface of the pressure plate 9 operating levers 10 intermediate levers 11 outer end of the actuating lever in radial direction 12 in radial direction inner end of the actuating lever 13 first end of the intermediate lever 14 second end of the intermediate lever 15 spring storage units 16 actuating bearings 17 interim storage facilities 18 First lever section of the intermediate lever 19 second lever section of the intermediate lever 20 push rod 21 friction-reducing device 22 Back of the counter-pressure plate 23 second lever tip 24 metal strips 25 wire rings 26 Wire ring section 27 Nut 28 coupling link A axial direction D axis of rotation R radial direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 23 57 860 C2

[0006] DE 31 42 107 A1

[0006]

Claims

[1] Friction clutch (1) comprising a housing (2), a housing-fixed counter-pressure plate (6), a pressure plate (4) which is displaceable to a limited extent in the axial 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) 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) outer in the radial direction (R) and a second end (14) inner in the radial direction (R), wherein the intermediate lever (10) is rotatably attached to the actuating lever (9) via an intermediate bearing (17), wherein the intermediate lever (10) acts on the pressure plate (4) at its first end (13) and is supported at its second end (14) by the counter-pressure plate (6), and wherein a friction-reducing device (21) is arranged between the second end (14) of the intermediate lever (10) and the counter-pressure plate (6). [2] Friction clutch (1) according to claim 1, wherein the second end (14) of the intermediate lever (10) is in direct contact with the counter-pressure plate (6), and the friction-reducing device (21) is designed as a surface modification, preferably as a surface hardness-increasing coating and / or as a surface roughness-reducing surface treatment, of the second end (14) of the intermediate lever (10) and / or of the contact area on a rear side (22) of the counter-pressure plate (6). [3] Friction clutch (1) according to claim 1 or 2, wherein the second end (14) of the intermediate lever (10) is designed as a flattened rounded lever tip (23). [4] Friction clutch (1) according to claim 1 or 3 without reference to claim 2, wherein the friction-reducing device (21) is designed as a sheet metal strip (24), preferably annular or ring-segment shaped, which rests against a rear side (22) of the counter-pressure plate (6) and against which the second end (14) of the intermediate lever (10) rests. [5] Friction clutch (1) according to claim 1, wherein the friction-reducing device (21) is designed as a wire ring (25) or wire ring section (26) arranged between the second end (14) of the intermediate lever (10) and a rear side (22) of the counter-pressure plate (6). [6] Friction clutch (1) according to claim 5, wherein the wire ring section (26) is inserted, preferably pressed into, the second end (14) of the intermediate lever (10). [7] Friction clutch (1) according to claim 5, wherein the wire ring (25) or wire ring section (26) is inserted into a groove (27) on the back (22) of the counter pressure plate (6). [8] Friction clutch (1) according to claim 1, wherein the friction-reducing device (21) is designed as a further coupling element (28) via which the second end (14) of the intermediate lever (10) is pivotally connected to a rear side (22) of the counter-pressure plate (6). [9] Friction clutch (1) according to any one of claims 1 to 8, wherein each of the actuating devices (5) has a preload spring by which the actuating lever (9) and / or the intermediate lever (10) is / are preloaded by the preload spring acting on the actuating lever (9) and / or the intermediate lever (10). [10] Friction clutch (1) according to any one of claims 1 to 9, wherein the housing (2) and the counter-pressure plate (6) are formed in one piece.

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