Torque-limiting device

Abstract

The invention relates to a torque-limiting device (1) for a hybridised drive train of a motor vehicle, having an input-side carrier disc (3) through which at least one friction lining element (2a) extends in the axial direction of the torque-limiting device (1), two side parts (5, 6) arranged on opposite sides (4a, 4b) of the carrier disc (3), and a disc spring (7), which presses a first (5) of the side parts (5, 6) against the at least one friction lining element (2a) with frictional force, wherein the disc spring (7) abuts with its first axial side (8a) against a second (6) of the side parts (5, 6) and abuts directly against the at least one friction lining element (2a) with its second axial side (8b), or acts on the friction lining element (2a) at least indirectly via a pressure plate abutting against the second axial side (8b).

Description

[0001] Torque limiting device

[0002] The invention relates to a torque limiting device for a hybridized powertrain of a motor vehicle, comprising an input-side carrier disc having at least one friction lining element, two side parts arranged opposite each other on the carrier disc, and a disc spring that frictionally presses a first of the side parts against the at least one friction lining element. The torque limiting device, also commonly referred to as a slip clutch or overload protection clutch, thus forms a permanently closed clutch that only opens (briefly) upon reaching a certain torque peak / impulse to allow rotation between the carrier disc and the side parts, thereby converting / dissipating this excess energy into heat. After the torque peak subsides, the clutch closes automatically again.

[0003] Torque limiting devices of this type are already well known from the prior art. For example, EP 2 226 528 A2 discloses a device for eliminating torque fluctuations with a limiting unit.

[0004] The increasing hybridization / electrification of powertrains has revealed that the torque limiting devices previously used for purely internal combustion engine powertrains are simply too large. Furthermore, they are often relatively expensive to manufacture and have a relatively complex design.

[0005] It is therefore an object of the present invention to provide a torque limiting device which is designed to be as efficient as possible, particularly for use in hybridized / hybrid drive trains, whereby a compact installation space and simpler manufacturability are to be achieved in particular.This problem is solved according to the invention by a torque limiting device for a hybridized powertrain of a motor vehicle according to claim 1, comprising an input-side carrier disc through which at least one friction lining element extends in the axial direction of the torque limiting device, two side parts arranged opposite each other on opposite sides of the carrier disc, and a disc spring which presses a first of the side parts against the at least one friction lining element in a frictionally interlocking manner, wherein the disc spring bears with its first axial side against a second of the side parts and with its second axial side bears directly against the at least one friction lining element or acts upon the friction lining element at least indirectly via a pressure plate bearing against the second axial side.

[0006] Further advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0007] Preferably, the friction lining element has a thickness measured in the axial direction that is greater than the thickness of the carrier disc measured in the axial direction.

[0008] In particular, the friction lining element preferably has a cross-section that, viewed in the axial direction, is constant over its entire extent, i.e., that is constant along the entire thickness of the friction lining element as measured in the axial direction. For example, the friction lining element can be cylindrical and thus have a circular cross-section that is constant along its entire thickness as measured in the axial direction.

[0009] Furthermore, it is advantageous if the friction lining element is axially displaceable relative to the carrier disc. This displaceability, which may require a certain amount of force, allows for the compensation of minor tilting of the individual components relative to each other during operation of the torque limiting device, and especially during the activation of the torque limiting device in the event of an overload, without the need for additional components. In this regard, it is also advantageous if the friction lining element protrudes on both (axial) sides (of the carrier disc) so that it is in frictional contact with both the first side part and the disc spring. This reduces the number of components required and allows for an even more compact design.

[0010] In this regard, it is particularly advantageous if at least one friction lining element is fixed in a through-hole of the carrier disc in the radial direction and circumferential direction of the torque limiting device, thus functioning as a so-called inlay. The friction lining element is, for example, shaped as a cylindrical body. This allows the required installation space to be further reduced in the axial direction.

[0011] In this regard, it is further advantageous if several friction lining elements are arranged circumferentially, preferably at the same radial height, distributed within the carrier disc. This makes it possible to individually adjust the minimum impulse required to open the torque limiting device by selecting the appropriate number of friction lining elements.

[0012] If the disc spring has a contact area adjacent to at least one friction lining element that runs flat / parallel to a counter-contact area of ​​the at least one friction lining element, the disc spring is designed to be as simple as possible.

[0013] Alternatively, it is also advantageous if the disc spring has a contact area adjacent to at least one friction lining element, which is part of a convex side of the disc spring. This ensures that the disc spring is designed to be as wear-resistant as possible with regard to its contact area.

[0014] In this regard, it has again proven advantageous if the disc spring has a contact area abutting the at least one friction lining element, which is part of an axially flared groove of the disc spring. Preferably, this groove can directly form the convex side or the (convex) contact area. This makes the disc spring as easy to manufacture as possible.

[0015] Furthermore, it has proven advantageous for the disc spring to be designed in such a way that it generates a constant force level within its operating range during operation, meaning that its spring-force characteristic curve remains constant within that range. "Constant" here refers specifically to deviations of less than + / - 5%.

[0016] If the side parts in turn form an input to a torsional vibration damper unit (the torque limiting device), the torque limiting device is also designed to be as compact as possible in terms of installation space in conjunction with vibration damping.

[0017] The invention will now be explained in more detail below with reference to figures, in which context different embodiments are also illustrated.

[0018] They show:

[0019] Figure 1 shows a perspective view of a first torque limiting device, cut in longitudinal direction, wherein an inserted carrier disc has a friction lining element on each of its two axial sides, which is in frictional contact either with a side part or with a disc spring,

[0020] Figure 2 shows a perspective view of a second torque limiting device, cut in longitudinal direction, in which several friction lining elements penetrating the carrier disc are now present, which are in frictional contact with both the side part and the disc spring.

[0021] Figure 3 shows a perspective view of part of the second torque limiting device according to Figure 2 from a front view in the uncut state, in which the circumferentially distributed friction lining elements are visible; Figure 4 shows a perspective view of a third torque limiting device, cut in the longitudinal direction, in which the disc spring differs in shape compared to the second torque limiting device and is now convexly curved in the area of ​​its contact area against the friction lining elements.

[0022] Figure 5 shows a fourth torque limiting device in perspective view, cut in longitudinal direction, in which the disc spring is now provided with an axially flared bead forming the contact area,

[0023] Figure 6 shows a perspective view of the disc spring used in the first and second torque limiting devices.

[0024] Figure 7 shows a perspective view of the disc spring used in the third torque limiting device.

[0025] Figure 8 shows a perspective view of the disc spring used in the fourth torque limiting device, as well as

[0026] Figure 9 shows a force-displacement characteristic curve of the disc spring used in the first and second torque limiting device, illustrating its preferably constant working range.

[0027] The figures are purely schematic and therefore serve solely to illustrate the invention. The same elements are identified by the same reference numerals. Furthermore, the various features of the different embodiments can, in principle, be freely combined.

[0028] A first torque limiting device is clearly illustrated in Figure 1. The torque limiting device 1 serves, in the usual manner, to protect the components of a motor vehicle powertrain that are downstream of it along the torque transmission flow. The torque limiting device 1 serves, in particular, to limit a transmitted torque / torque impulse and thus forms a protective clutch. The torque limiting device 1 is therefore implemented as a friction clutch / slip clutch, which opens briefly when an applied torque impulse is exceeded, thereby selectively converting and dissipating this impulse into heat energy so that it is not transmitted further in the powertrain. The torque limiting device 1 is therefore, in particular, a non-externally actuated friction clutch / slip clutch, i.e.,a friction clutch / slip clutch on which no actuation system / release system / engagement system acts.

[0029] The torque limiting device 1 is used in a conventional manner in a hybridized powertrain of a motor vehicle, in particular along the torque transmission flow seen between at least one drive machine, such as an internal combustion engine and / or an electric machine, and a transmission.

[0030] The torque limiting device 1, as can also be seen in Figure 1, includes a torsional vibration damper unit 15 in the usual manner. The torsional vibration damper unit 15 has an inlet 14 and an outlet 16, which are supported relative to each other in the circumferential direction / direction of rotation by means of several spring elements 17 (for example, coil springs).

[0031] In this embodiment, the inlet 14 of the torsional vibration damper unit 15 is formed directly by two axially spaced side parts 5, 6, wherein the axis of rotation of the torque limiting device 1 or the torsional vibration damper unit 15 is defined as the axis about which the two side parts 5, 6 can be rotated during operation of the torque limiting device 1 or the torsional vibration damper unit 15. The two side parts 5, 6 are arranged axially on both sides of a carrier disk 3. The two side parts 5, 6 overlap the carrier disk 3 radially, particularly in the area of ​​two friction lining elements 2a, 2b arranged on it. As explained in more detail below, the side parts 5, 6 and the carrier disk 3 form a slip clutch unit 18 of the torque limiting device 1.A first side part 5, or indirectly both side parts 5, 6, are pressed axially against the friction lining elements 2a, 2b with a predetermined contact force, forming a frictional connection with them. The carrier disc 3 is arranged on the input side of the slip clutch unit 18; the side parts 5, 6 are arranged on the output side of the slip clutch unit 18. As already explained, the side parts 5, 6 also form the input of the torsional vibration damper unit 15.

[0032] In this embodiment, the friction lining elements 2a, 2b are attached / fastened to one side 4a, 4b of the carrier disc 3. The friction lining elements 2a, 2b are, in this embodiment, disc-shaped as a ring or formed by several arcuate segments.

[0033] The first side part 5 is arranged on the first side of the carrier disc 4a and rests directly against the first friction lining element 2a. The second side part 6 is arranged on the second side 4b. However, the second side part 6 is not in direct contact with the second friction lining element 2b. Instead, a disc spring 7 is interposed between the second side part 6 on the one hand and the second friction lining element 2b on the other.

[0034] The disc spring 7 is thus in axial contact with the second side part 6 with its first axial side 8a and in direct contact with the second friction lining element 2b with its second axial side 8b. The disc spring 7 preferably forms several circumferentially spaced-apart contact lugs 19 on its section forming the first axial side 8a, which bear against the second side part 6.

[0035] The disc spring 7, as can also be seen in Figure 6, has a contact area 10 facing the second friction lining element 2b, which is formed by a flat surface / annular surface. In this embodiment, the disc spring 7 is flat over the entire radial height of the second friction lining element 2b, i.e., parallel to a counter-contact area 11 / counter-contact surface of the second friction lining element 2b. This results in full-surface contact between the second friction lining element 2b and the disc spring 7 during operation. A preload force / closing force of the slip clutch unit 18 is thus generated by the force / spring force applied by the disc spring 7, which is determined by its clamping and design.

[0036] In this regard, it can be seen in Figure 9 that the disc spring 7 is designed and installed in such a way that it is always in a constant / linear force-displacement range over its working range during the operation of the torque limiting device 1.

[0037] Figures 2 to 5, 7 and 8 below describe further torque limiting devices 1, whose basic function and basic structure, however, correspond to the first torque limiting device 1. For the sake of brevity, only the essential differences between the subsequent torque limiting devices 1 and the first torque limiting device 1, or between them, are described.

[0038] The second torque limiting device 1 in Figures 2 and 3 shows that, compared to Figure 1, the friction lining elements 2a, 2b can be configured differently. Instead of two groups of friction lining elements 2a, 2b being in contact with either the first side part 5 or the disc spring 7, there is now only one friction lining element 2a / one group of friction lining elements 2a. The carrier disc 3 accommodates several circumferentially distributed friction lining elements 2a, which are in contact with both the first side part 5 and the disc spring 7. The friction lining elements 2a are in frictional contact with the first side part 5 at a first axial side / end face and with the disc spring 7 at a second axial side / end face, which faces away from the first axial side.The friction lining elements 2a, arranged circumferentially on the carrier disc 3, are thus each in frictional contact with both the first side part 5 and the disc spring 7. In other words, a torque limiting device 1 for a hybridized powertrain of a motor vehicle is disclosed, comprising an input-side carrier disc 3 through which at least one friction lining element 2a extends in the axial direction of the torque limiting device 1, two side parts 5, 6 facing away from each other (sides 4a, 4b) of the carrier disc 3, and a disc spring 7, which presses a first 5 of the side parts 5, 6 against the at least one friction lining element 2a by frictional force. The disc spring 7 rests with its first axial side 8a against a second 6 of the side parts 5, 6 and with its second axial side 8b directly against the at least one friction lining element 2a.Alternatively, the disc spring 7 can act on the friction lining element 2a at least indirectly via a pressure plate located on the second axial side 8b.

[0039] The friction lining element 2a has a thickness, measured in the axial direction, that is greater than the thickness of the carrier disk 3, also measured in the axial direction. The friction lining element 2a has a cross-section that, viewed in the axial direction, is constant over its entire extent; that is, it remains constant along its entire thickness measured in the axial direction. For example, as can be seen from the combined view of Figures 2 and 3, the friction lining element 2a can be cylindrical and thus have a circular cross-section that remains constant along its entire thickness measured in the axial direction.

[0040] Furthermore, the friction lining element 2a is axially displaceable relative to the carrier disc 3. Ideally, the friction lining element 2a projects on both sides 4a, 4b of the carrier disc 3, so that it is in frictional contact with both the first side part 5 and the disc spring 7.

[0041] In particular, the friction lining element 2a is fixed in a through-hole 9 of the carrier disc 3 in the radial direction of the torque limiting device 1 and in the circumferential direction of the torque limiting device 1. It is understood that the preceding explanations also apply to multiple friction lining elements 2a arranged circumferentially within the carrier disc 3. Figure 3 shows that the friction lining elements 2a are each implemented as inlays. A plurality of friction lining elements 2a are anchored in the carrier disc 3. The friction lining elements 2a are preferably arranged at the same radial height, i.e., at the same diameter. In this case, the friction lining elements 2a are implemented as cylindrical bodies / blocks that are inserted into through-holes 9 of the carrier disc 3, for example, by welding or pressing them in.

[0042] The friction lining elements 2a thus formed naturally protrude from / forward of each side 4a, 4b of the carrier disc 3 by a certain amount in order to form counter-contact areas to the first side part 5 or the disc spring 7, which are arranged spaced apart from the carrier disc 3 itself.

[0043] With regard to the torque limiting devices 1 and their disc springs 7 in Figures 4, 5, 7 and 8, it can also be seen that it is in principle possible to shape the disc spring 7 differently.

[0044] In the third torque limiting device 1 of Figure 4 in conjunction with Figure 7, it can be seen that it is also possible to design the disc spring 7 in a bent / curved form. The disc spring 7 is shaped such that its convex area / convex side 12 directly forms the contact area 10, which rests against the friction lining elements 2a. In this embodiment, the disc spring 7 is curved over its entire radial height when viewed in the radial direction, for example, continuously curved.

[0045] Finally, in the fourth torque limiting device 1 of Figure 5 in conjunction with Figure 8, it can be seen that it is alternatively possible to provide the disc spring 7 with a preferably fully circumferential groove 13. This groove 13 forms a convex contact area 10, which is in contact with the friction lining elements 2a. The groove 13 is positioned such that it rests radially centrally against the friction lining elements 2a. In other words, the disc spring 7, preferably with a flat bearing surface, rests directly on the friction lining (friction lining element 2a; 2b) (Figure 1). Alternatively, the friction lining can be replaced by inlays (Figure 2). To optimize the torque transmission (mean friction diameter), the flat disc spring bearing surface can be replaced by a convex disc spring bearing surface (Figure 4) or a grooved disc spring (Figure 5).

[0046] The force characteristic of the disc spring 7 is preferably designed such that an almost constant force level is present in the working area around the flat position (ratio of free installation height to material thickness « 2).

[0047] Figure 1 further shows that the flat disc spring 7 is supported inwards by support lugs 19 on the side plate (second side part 6). The lever arm should be as large as possible to minimize installation tolerances. This reduces the bearing diameter on the side plate, and the outer diameter of the side plate can be reduced. This leads to further cost savings. The inner area of ​​the disc spring 7 is cost-neutral, as it is stamping waste. The support lugs 19 of the disc spring 7 can be used for (radial) centering (relative to the second side part 6).

[0048] Instead of the flat disc spring support, a convex friction contact (Figure 4) or a beaded disc spring (Figure 5) can also be used. However, these two variants require an additional manufacturing step and slightly more axial installation space.

[0049] Instead of two rotating friction linings, lining inlays (as shown in Figures 2 and 3) can also be used for all variants. Reference symbol list

[0050] Torque limiting device a first friction lining element b second friction lining element

[0051] Carrier disc a first side of the carrier disc b second side of the carrier disc first side part second side part

[0052] Disc spring a first axial side of the disc spring b second axial side of the disc spring

[0053] Through hole 0 Contact area 1 Counter-contact area 2 Convex side 3 Bead 4 Inlet 5 Torsional vibration damper unit 6 Outlet 7 Spring element 8 Slip clutch unit 9 Support tongue

Claims

Patent claims 1. Torque limiting device (1) for a hybridized powertrain of a motor vehicle, comprising an input-side carrier disc (3) through which at least one friction lining element (2a) extends in the axial direction of the torque limiting device (1), two side parts (5, 6) arranged opposite each other on opposite sides (4a, 4b) of the carrier disc (3), and a disc spring (7) which presses a first (5) of the side parts (5, 6) against the at least one friction lining element (2a) in a frictionally engaging manner, characterized in that the disc spring (7) bears with its first axial side (8a) against a second (6) of the side parts (5, 6) and bears with its second axial side (8b) directly against the at least one friction lining element (2a) or acts on the friction lining element (2a) at least indirectly via a pressure plate bearing against the second axial side (8b).

2. Torque limiting device (1) according to claim 1 , characterized in that the friction lining element (2a) has a thickness measured in the axial direction which is greater than the thickness of the carrier disk (3) measured in the axial direction.

3. Torque limiting device (1) according to claim 2, characterized in that the friction lining element (2a) has a cross-section that is constant along the entire thickness measured in the axial direction.

4. Torque limiting device (1) according to one of claims 1 to 3, characterized in that the friction lining element (2a) is displaceable in the axial direction with respect to the carrier disc (3).

5. Torque limiting device (1) according to one of claims 1 to 4, characterized in that the friction lining element (2a) is connected to both sides (4a, 4b) of the carrier disc (3) protrude, so that it is in frictional contact with both the first side part (5) and the disc spring (7).

6. Torque limiting device (1) according to one of claims 1 to 5, characterized in that the friction lining element (2a) is fixed in a through hole (9) of the carrier disk (3) in the radial direction of the torque limiting device (1 ) and in the circumferential direction of the torque limiting device (1 ).

7. Torque limiting device (1) according to one of claims 1 to 6, characterized in that several friction lining elements (2a) are arranged in the carrier disc (3) distributed in the circumferential direction.

8. Torque limiting device (1) according to one of claims 1 to 7, characterized in that the disc spring (7) has a contact area (10) abutting the at least one friction lining element (2a), which runs parallel to a counter-contact area (11) of the at least one friction lining element (2a).

9. Torque limiting device (1) according to one of claims 1 to 7, characterized in that the disc spring (7) has a contact area (10) abutting the at least one friction lining element (2a), which is part of a convex side (12) of the disc spring (7).

10. Torque limiting device (1) according to one of claims 1 to 7, characterized in that the disc spring (7) has a contact area (10) abutting the at least one friction lining element (2a), which is part of an axially flared groove (13) of the disc spring (7).

11. Torque limiting device (1) according to one of claims 1 to 9, characterized in that the disc spring (7) is designed such that it generates a constant force level in its working range during operation. - 15 - 12. Torque limiting device (1) according to one of claims 1 to 11 , characterized in that the side parts (5, 6) in turn form an inlet (14) of a torsional vibration damper unit (15).

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