Slip clutch

Abstract

The invention relates to a slip clutch (1) for a motor vehicle, comprising at least one flange disk (2) as input part and at least two counter disks (3, 4) as output part, which have a common axis of rotation (5); wherein the flange disk (2) is arranged along the axis of rotation (5) between the counter disks (3, 4) and is connected to a force transmission surface (6) of each counter disk (3, 4) only by frictional engagement relative to a circumferential direction (7); wherein at least one of the counter disks (3, 4) has a structure (8) extending along the circumferential direction (7) on the force transmission surface (6), which comprises a plurality of elevations (10) projecting in the direction of the axis of rotation (5) relative to an otherwise flat surface (9) of the force transmission surface (6), which are arranged distributed along the circumferential direction (7).

Description

[0001] The invention relates to a slip clutch for a motor vehicle, in particular for a motor vehicle, e.g., with at least one electric motor as at least one drive unit, e.g., a hybrid vehicle. In particular, the slip clutch is used together with a vibration damper. The slip clutch serves in particular as a torque limiter.

[0002] A torque limiter is used primarily to protect a powertrain. It prevents torque exceeding a certain limit from being transmitted. For example, in hybrid powertrains, a torque limiter is located between the flywheel of the combustion engine and the vibration damper on the transmission input shaft.

[0003] The torque limiter's function is to protect components such as the transmission input shaft and other related drivetrain components from overload. These overloads can occur when excessive torque is generated or transmitted between the combustion engine and the transmission input shaft.

[0004] Torque limiters of this type operate primarily on the principle of friction. If the clamping force acting on the plates and friction linings is insufficient to transmit the torque exceeding a certain limit, the plates and friction linings slip relative to each other. When the torque falls below the specified limit again, no relative twisting occurs between the plates and friction linings, and the torque is transmitted completely.

[0005] A vibration damper (also known as a torsional vibration damper) incorporates intentionally introduced torsional compliances in a drive train excited by periodic disturbances. The vibration damper comprises, for example, a primary and a secondary part, as well as at least one spring element. When a torque is transmitted along a circumferential direction, the primary and secondary parts are rotatable relative to each other within a limited range against the spring force of the spring element. The aim is to shift the disruptive vibration resonances occurring in various operating conditions to a speed range preferably below the operating speeds. Vibration resonances remaining within the operating speed range are damped by an external or integrated friction device whose frictional torque must be within defined limits. The friction device can, in particular, be designed independently of the torsional compliance.

[0006] A key criterion for the quality of torque limiters and slip clutches is the consistency of the friction coefficients and frictional torques over their service life. All friction pairings require a certain frictional distance and energy until the surfaces have adapted to each other. During this conditioning phase (also known as the break-in period), the friction coefficient, and therefore the release and sliding frictional torques of the slip clutch, can change.

[0007] For the design of torque limiters or slip clutches, this means that changes in friction coefficients must be accepted and the system designed accordingly to ensure it functions within the given limits despite these fluctuations in frictional torque or coefficient of friction (lower quality). Alternatively, if the given limits do not permit the increased scatter of frictional torques or coefficients of friction, the friction pair must be run in during the production process to achieve a steady state upon delivery (higher costs).

[0008] It is known that friction can be changed (reduced) if the interacting friction surfaces have non-uniform stiffnesses.

[0009] Based on this, the present invention aims to at least partially alleviate the problems described above. In particular, a slip clutch is proposed as a torque limiter which exhibits a high degree of consistency in friction coefficients and frictional torques immediately after assembly and preferably throughout its service life.

[0010] This problem is solved by a slip clutch according to the features of independent claim 1. Further advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technologically meaningful manner and can define further embodiments of the invention. In addition, the features specified in the claims are further specified and explained in the description, whereby further preferred embodiments of the invention are presented.

[0011] A slip clutch for a motor vehicle is proposed. The slip clutch comprises at least one flanged disc as the input part and at least two mating discs as the output part, which have a common axis of rotation. The flanged disc is arranged along the axis of rotation between the mating discs and is frictionally connected to a force transmission surface of each mating disc in one circumferential direction. At least one of the mating discs has a circumferentially extending structure on its force transmission surface, comprising a plurality of raised areas projecting in the direction of rotation relative to an otherwise flat surface of the force transmission surface, which are distributed along the circumferential direction.

[0012] In operation of the slip clutch, e.g., in a motor vehicle, the flange disc is connected to the mating discs only by frictional engagement with respect to the circumferential direction. The mating discs are connected to each other in a rotationally fixed manner with respect to the circumferential direction. The mating discs exert a clamping force on the flange disc along the axis of rotation. If a slip torque is exceeded (e.g., a defined or predetermined torque value), the flange disc slips relative to the mating discs.

[0013] The flange disc is contacted by the mating discs in an annular area. The mating discs contact the flange disc on the same or different diameters. This contact area of ​​the flange disc is defined by a first (smaller) diameter and a second (larger) diameter. The annular surfaces of the mating discs opposite this area are specifically referred to as force transmission surfaces.

[0014] In particular, these raised sections are the only elements of the mating disc that are in contact with a friction lining or with the mating disc itself, and thus define the lever arm of the force application point and therefore the force or torque of the slip clutch. As a result of these raised sections, the surface pressure is variable along the circumferential direction, so that friction can be reduced and made more uniform.

[0015] In particular, the structure is interrupted between the elevations and is formed there by the flat surface of the force transmission surface.

[0016] In particular, the raised sections are all identical in shape, meaning they have the same extent in the circumferential direction, in the direction of the axis of rotation, and in a radial direction. Each raised section extends, for example, over an angular range of at least one degree, in particular at least five degrees, preferably at least ten degrees. Each raised section extends, in particular, over an angular range of at most 45 degrees, preferably at most 25 degrees, and most preferably at most 15 degrees.

[0017] In particular, the elevations along the circumference are arranged at regular or equal intervals from one another.

[0018] In particular, the structure extends along the circumference in a wave-like pattern, forming maxima and minima, with each maximum forming one of the elevations. Specifically, at least in the region of the maxima, the structure exhibits sections that are not curved but extend parallel to the circumference. Alternatively, the structure exhibits a consistently curved profile along the circumference.

[0019] In particular, the minima are arranged in a common plane with the otherwise flat surface of the force transmission surface.

[0020] In particular, the flange disc is designed as a disc spring. Specifically, the mating discs contact the flange disc, which is designed as a disc spring, at different diameters or in (annular) diameter ranges (which preferably do not overlap along the radial direction, but are spaced apart along the radial direction) and preload the disc spring. The preload can be adjusted or defined, for example, by the inclination of the disc spring, the diameters on which the contact occurs, and by the orientation of the mating discs relative to each other.

[0021] In particular, each of the counter disks has the structure, with the structures being arranged on different diameters.

[0022] In particular, the mating discs contact the flange disc directly, forming a steel-to-steel friction connection. The mating disc contacts the flange disc exclusively via the raised sections.

[0023] Alternatively, a friction lining is arranged between at least one of the counter disks and the flange disk, preferably between each counter disk and the flange disk. The (respective) counter disk contacts the friction lining with the structure exclusively via the raised areas.

[0024] Of course, it is also possible that there is direct contact between one counter disk and the flange disk, while a friction lining is provided between the other counter disk and the flange disk.

[0025] In particular, the friction lining is connected to the counter disk or the flange disk in a rotationally fixed manner.

[0026] In particular, the counter-discs are connected to each other via a plurality of rivet connections arranged along the circumferential direction.

[0027] In particular, the slip clutch additionally comprises a vibration damper having a primary part and a secondary part as well as at least one spring element, wherein the primary part and the secondary part are rotatable relative to each other in a limited manner against a spring force of the spring element when a torque is transmitted along the circumferential direction. The flange disc forms the primary part or the secondary part.

[0028] In particular, the flange disc features a stop element that interacts with the spring element. This allows, for example, a torque to be introduced via the primary part of the vibration damper and transmitted to the secondary part via the spring element. For instance, the flange disc forms the secondary part of the vibration damper and the input part of the slip clutch. The torque can then be transmitted via the frictional connection to the mating discs, which serve as the output part. Naturally, the reverse transmission is also possible. Furthermore, it is possible to connect or arrange the primary and secondary parts of the vibration damper with the flange disc or the mating discs in other ways.

[0029] Counter disks and flange disks are connected to the vibration damper in a generally known manner.

[0030] A motor vehicle drivetrain is further proposed, comprising at least a flywheel of a power engine and the described slip clutch. The flywheel is, in particular, rotationally fixed to the input part or to the output part (or to the primary part or the secondary part) of the slip clutch with respect to the circumferential direction.

[0031] The use of indefinite articles (“a”, “an”, “one”, and “ones”), particularly in the patent claims and the description reproducing them, is to be understood as such and not as a numeral. Accordingly, terms or components introduced by these articles are to be understood as occurring at least once and, in particular, may also occur multiple times.

[0032] It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. Where a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or some of the multiple components, but this is not mandatory.

[0033] The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description. In particular, it should be noted that the figures, and in particular the proportions shown, are only schematic. They show: Fig. 1: a section of a slip clutch in a perspective view; Fig. 2: a known embodiment of a counter disk in a view along the axis of rotation; Fig. 3: a first design variant of a counter disk in a view along the axis of rotation; Fig. 4: the counter disk after Fig. 3 in a perspective view; Fig. 5: a second variant of a counter disk in a view along the axis of rotation; and Fig. 6: the counter disk after Fig. 5 in a perspective view.

[0034] Fig. Figure 1 shows a section of a slip clutch 1 in a perspective view.

[0035] The slip clutch 1 comprises a flanged disc 2 as the input part and two counter discs 3, 4 as the output part, which have a common axis of rotation 5. The flanged disc 2 is arranged along the axis of rotation 5 between the counter discs 3, 4 and is connected to a force transmission surface 6 of each counter disc 3, 4 by friction only in a circumferential direction 7. Each of the counter discs 3, 4 has a structure 8 extending along the circumferential direction 7 on the force transmission surface 6, which comprises a plurality of protrusions 10 projecting in the direction of the axis of rotation 5 relative to an otherwise flat surface 9 of the force transmission surface 6, and which are distributed along the circumferential direction 7 (see Fig. 3 to 6).

[0036] It is indicated that the slip clutch 1 additionally comprises a vibration damper 16, which has a primary part 17 and a secondary part 18 as well as a spring element 19, wherein the primary part 17 and the secondary part 18 are rotatable relative to each other against a spring force of the spring element 19 when a torque is transmitted along the circumferential direction 7. The flange disk 2 forms the secondary part 18.

[0037] The flange disc 2 has a stop element 20 that interacts with the spring element 19. This allows a torque to be introduced via the primary part 17 of the vibration damper 16 and transmitted via the spring element 19 to the secondary part 18. For example, the flange disc 2 forms the secondary part 18 of the vibration damper 16 and simultaneously the input part of the slip clutch 1. The torque can then be transmitted via the frictional connection to the counter discs 3, 4, which serve as the output part. Naturally, the reverse transmission of torques is also possible.

[0038] A friction lining 14 is arranged between each of the counter disks 3, 4 and the flange disk 2. The respective counter disk 3, 4 contacts the friction lining 14 with the structure 8 exclusively via the protrusions 10.

[0039] The flange disk 2 is contacted by the mating disks 3, 4 in an annular area. The mating disks 3, 4 contact the flange disk 2 at different diameters 12, 13 via the structure 8 and its raised portions 10, respectively. This contact area of ​​the flange disk 2 is bounded by a first (smaller) diameter 12 and a second (larger) diameter 13. The annular surfaces of the mating disks 3, 4 opposite this area are referred to as force transmission surfaces 6.

[0040] The flange disk 2 is designed as a disc spring. The counter disks 3, 4 contact the flange disk 2, which is designed as a disc spring, on different diameters 12, 13 or in diameter ranges (which do not overlap along the radial direction 21, but are spaced apart from each other along the radial direction 21) and preload the disc spring. The preload can be adjusted or defined, for example, by the inclination of the disc spring, the diameters 12, 13 on which the contact occurs, and by the orientation of the counter disks 3, 4 relative to each other.

[0041] In operation of the slip clutch 1, e.g., in a motor vehicle, the flange disc 2 is connected to the mating discs 3, 4 only by frictional engagement relative to the circumferential direction 7. The mating discs 3, 4 are rotationally fixed to each other relative to the circumferential direction 7 by rivet connections 15. The mating discs 3, 4 exert a clamping force on the flange disc 2 along the axis of rotation 5. If a slip torque is exceeded (e.g., a defined or predetermined value of torque), the flange disc 2 slips relative to the mating discs 3, 4.

[0042] Fig. Figure 2 shows a known embodiment of a first counter disk 3 in a view along the axis of rotation 5. See the explanations regarding Fig. Reference is made to point 1.

[0043] The structure 8 is formed by a continuous elevation 10 along the circumferential direction 7.

[0044] Fig. Figure 3 shows a first embodiment of a counter disk 3 in a view along the axis of rotation 5. Fig. 4 shows the opposite disc Fig. 3 in a perspective view. The Fig. 3 and Fig. The four sections are described together below. The explanations regarding the Fig. 1 and Fig. 2 is referred to.

[0045] The structure 8 comprises a multitude of protrusions 10 projecting in the direction of the axis of rotation 5 compared to an otherwise flat surface 9 of the force transmission surface 6, which are arranged distributed along the circumferential direction 7.

[0046] These raised areas 10 are the only elements of the counter disk 3 that are in contact with the friction lining 14 and thus define the lever arm of the force application point and therefore the force or torque of the slip clutch 1.

[0047] The structure 8 is interrupted between the elevations 10 and is formed there by the flat surface 9 of the force transmission surface 6.

[0048] The raised sections 10 are all identical in shape, meaning they have the same extent in the circumferential direction 7, in the direction of the axis of rotation 5, and in a radial direction 21. Each raised section 10 extends over an angular range of approximately 25 degrees. The raised sections 10 are arranged at regular intervals along the circumferential direction 7.

[0049] Fig. Figure 5 shows a second embodiment of a counter disk 3 in a view along the axis of rotation 5. Fig. 6 shows the opposite disc 3 after Fig. 5 in a perspective view. The Fig. 5 and Fig. The six will be described together below. The explanations regarding the Fig. Reference is made to 1 to 4.

[0050] The structure 8 extends along the circumferential direction 7 in a wave-like pattern, forming maxima and minima 11, with each maximum forming one of the elevations 10. At least in the region of the maxima, the structure 8 has sections that are not curved but extend along the circumferential direction 7 parallel to the circumferential direction 7 or parallel to the surface 9 of the force transmission surface 6. The minima 11 are arranged in a common plane with the otherwise flat surface 9 of the force transmission surface 6. Reference symbol list 1 slip clutch 2 flange disc 3 first counter disk 4 second counter disk 5 axis of rotation 6 Power transmission area 7 Circumferential direction 8 Structure 9 area 10 increase 11 Minimum 12 First diameter 13 second diameter 14 friction lining 15 rivet connection 16 vibration dampers 17 Primary part 18 Secondary part 19 spring element 20 stop elements 21 radial direction

Claims

[1] A slip clutch (1) for a motor vehicle, comprising at least one flanged disk (2) as the input part and at least two counter-disks (3, 4) as the output part, which have a common axis of rotation (5); wherein the flanged disk (2) is arranged along the axis of rotation (5) between the counter-disks (3, 4) and is only non-positively connected to a respective force-transmitting surface (6) of each counter-disk (3, 4) relative to a circumferential direction (7); wherein at least one of the counter-disks (3, 4) has, on the force-transmitting surface (6), a structure (8) extending along the circumferential direction (7), which structure comprises a plurality of elevations (10) projecting in the direction of the axis of rotation (5) relative to an otherwise flat surface (9) of the force-transmitting surface (6), which elevations are distributed along the circumferential direction (7). [2] Slip clutch (1) according to claim 1, wherein the structure (8) is interrupted between the elevations (10) and is formed by the flat surface (9) of the force transmission surface (6). [3] Slip clutch (1) according to claim 1, wherein the structure (8) extends in a wave-like manner along the circumferential direction (7) and thereby forms maxima and minima (11), each maximum forming one of the elevations (10). [4] Slip clutch (1) according to one of the preceding claims, wherein the flange disc (2) is designed as a disc spring. [5] Slip clutch (1) according to one of the preceding claims, wherein each of the counter-disks (3, 4) has the structure (8), wherein the structures (8) are arranged on mutually different diameters (12, 13). [6] Slip clutch (1) according to one of the preceding claims, wherein the counter discs (3, 4) directly contact the flange disc (2) and thereby form a steel-to-steel friction connection with one another; wherein the counter disc (3, 4) with the structure (8) contacts the flange disc (2) exclusively via the elevations (10). [7] Slip clutch (1) according to one of the preceding claims 1 to 6, wherein a friction lining (14) is arranged between at least one of the counter-disks (3, 4) and the flange disc (2); wherein the counter-disk (3, 4) with the structure (8) contacts the friction lining (14) exclusively via the elevations (10). [8] Slip clutch (1) according to claim 7, wherein the friction lining (14) is connected in a rotationally fixed manner to the counter-disk (3, 4) or to the flange disc (2). [9] Slip clutch (1) according to one of the preceding claims, wherein the counter-disks (3, 4) are connected to one another via a plurality of riveted connections (15) arranged distributed along the circumferential direction (7). [10] Slip clutch (1) according to one of the preceding claims, at least comprising a vibration damper (16) which has a primary part (17) and a secondary part (18) and at least one spring element (19), wherein the primary part (17) and the secondary part (18) are rotatable relative to one another to a limited extent against a spring force of the spring element (19) when a torque is transmitted along the circumferential direction (7); wherein at least the flange disc (2) forms the primary part (17) or the secondary part (18).

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