Torque limiter for a drivetrain

Abstract

A torque limiter for a drivetrain includes a friction lining, a drive side, and an output side, connected to the drive side by the friction lining until a limiting torque is reached. The torque limiter also has a first friction surface on the drive side or the output side, a first contact surface between the friction lining and the first friction surface, a second friction surface on the other of the drive side or the output side, and a second contact surface between the friction lining and the second friction surface. The first contact surface has a first mean friction radius and the second contact surface has a second mean friction radius, different than the first mean friction radius. When the limiting torque is exceeded, the friction lining is positioned slidingly on the first friction surface, and the friction lining is frictionally connected to the second friction surface.

Claims

1.-10. (canceled)

11. A torque limiter for a drivetrain, comprising: an axis of rotation extending along an axial direction; a friction lining under a pre-stress acting in the axial direction; a drive side; an output side connected to the drive side by the friction lining in a torque-transmitting manner until a limiting torque is reached; a first friction surface on a one of the drive side or the output side; a first contact surface between the friction lining and the first friction surface, the first contact surface comprising a first mean friction radius; a second friction surface on the other of the drive side or the output side; a second contact surface between the friction lining and the second friction surface, the second contact surface comprising a second mean friction radius, different than the first mean friction radius, wherein: when the limiting torque is exceeded: the friction lining is positioned slidingly on the first friction surface; and the friction lining is frictionally connected to the second friction surface.

12. The torque limiter of claim 11, wherein the first mean friction radius is smaller than the second mean friction radius.

13. The torque limiter of claim 12, wherein the first mean friction radius is at least 1% smaller than the second mean friction radius.

14. The torque limiter of claim 11 further comprising a cutout: disposed on the friction lining or the first friction surface, reducing the first contact surface and reducing the first mean friction radius; or disposed on the friction lining or the second friction surface, reducing the second contact surface and increasing the second mean friction radius.

15. The torque limiter of claim 14 wherein the cutout is disposed on the friction lining or the second friction surface, reducing the second contact surface.

16. The torque limiter of claim 15, wherein the cutout is located radially inward of the first mean friction radius.

17. The torque limiter of claim 14, wherein the cutout is continuous in a circumferential direction.

18. The torque limiter of claim 14, wherein the second contact surface extends in a circumferential direction at a constant first radius, the second contact surface comprising an edge bordering on the cutout.

19. The torque limiter of claim 11, further comprising an elevation, wherein the elevation is disposed on the first contact surface and extends in the axial direction towards the friction lining to reduce the first mean friction radius; or the elevation is disposed on the second contact surface and extends in the axial direction towards the friction lining to increase the second mean friction radius.

20. A drivetrain for a motor vehicle, comprising: the torque limiter of claim 11; a first drive unit for providing a first drive torque; and a second drive unit for providing a second drive torque, connected to the first drive unit in a torque-transmitting manner by the torque limiter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The disclosure as well as the technical environment will be explained in greater detail below on the basis of the figures. It should be pointed out that the disclosure is not to be limited by the exemplary embodiments shown. In particular, it is also possible, unless explicitly shown otherwise, to extract partial aspects of the circumstances explained in the figures and to combine them with other components and insights from the present description and/or figures. In particular, it must be pointed out that the figures, and especially the depicted size proportions, are only schematic. Like reference labels designate like objects, so that explanations from other figures may be cited in addition, as appropriate. In the figures:

[0028] FIG. 1 shows a first variant embodiment of a known torque limiter in a drivetrain, in a side cross sectional view;

[0029] FIG. 2 shows a second variant embodiment of a known torque limiter in a side cross sectional view;

[0030] FIG. 3 shows a detail of FIG. 1;

[0031] FIG. 4 shows a torque limiter having differing mean friction radii, in a side cross sectional view; and

[0032] FIG. 5 shows a detail of FIG. 4.

DETAILED DESCRIPTION

[0033] FIG. 1 shows a first variant embodiment of a known torque limiter 1 in a drivetrain 2, in a side cross sectional view. The drivetrain 2 has a first drive unit 21 (for example an internal combustion engine) for providing a first drive torque 22, and a second drive unit 23 (for example an electric machine) for providing a second drive torque 24. The first drive torque 22 acts directly on the drive side 5 of the torque limiter 1. The second drive torque 24 acts directly on the output side 6 of the torque limiter. The output side 6 may further be connected in a torque-transmitting manner to a transmission (not shown here). A torsion damper 25 is positioned on the output side 6 inside of the friction linings 7, 8 in a radial direction 18. The first drive unit 21 and the second drive unit 23 can be connected with one another in a torque-transmitting manner by means of the torque limiter 1, and can be separated from one another when a limiting torque is reached.

[0034] The torque limiter 1 has an axis of rotation 4 extending in an axial direction 3, as well as a drive side 5 and an output side 6, which are connected with one another in a torque-transmitting manner through two friction linings 7, 8 and under a pre-stress 9 acting in the axial direction 3, at least until a limiting torque acting in a circumferential direction 10 is reached. The output side 5 is positioned between the first friction lining 7 and the second friction lining 8. The output side 6 here includes two plates, between which the friction linings 7, 8 and the drive side 5 are positioned. Positioned between one plate of the output side 6 and one friction lining 7, 8 (here the second friction lining 8) is a bias spring, which produces the requisite stress 9 for the frictional connection.

[0035] During operation of the drivetrain 2, when the limiting torque is exceeded, the friction linings 7, 8 are disposed slidingly on a first friction surface 11 which is present only on one of the drive side 5 and output side 6 (here on the output side 6), and is frictionally connected to a second friction surface 12 which is present on the other of the drive side 5 and output side 6 (here on the drive side 5).

[0036] The friction linings 7, 8, the axis of rotation 3, and the drive side 5 and output side 6 are arranged coaxially to each other.

[0037] FIG. 2 shows a second variant embodiment of a known torque limiter 1 in a side cross sectional view. See the comments on FIG. 1. In contrast to the first variant embodiment, in the second variant embodiment the output side 6 is positioned between the first friction lining 7 and the second friction lining 8. The drive side 5 here includes two plates, between which the friction linings 7, 8 and the output side 6 are positioned. Positioned between one plate of the drive side 5 and one friction lining 7, 8 (here the second friction lining 8) is a bias spring, which produces the requisite stress 9 for the frictional connection.

[0038] FIG. 3 shows a detail of FIG. 1. See the comments on FIG. 1. When the limiting torque is exceeded, the friction linings 7, 8 are disposed slidingly on the first friction surface 11 (the latter is positioned on the output side 6 here). The friction linings 7, 8 continue to be connected frictionally to the second friction surface 12 (positioned on the drive side 5 here). This is realized in the variant embodiments shown in FIGS. 1 through 3 by a material connection (for example by cementing) or a positive connection (for example intermeshing profiles or rivets) between the second friction surface 12 and the respective friction lining 7, 8.

[0039] FIG. 4 shows a torque limiter 1 having differing mean friction radii 14, 16, in a side cross sectional view. See the comments on FIGS. 1 and 3. In contrast to the known first embodiment variant depicted there, here a cutout 17 is provided in the area of the second contact surface 15.

[0040] A first contact surface 13 between each friction lining 7, 8 and the first friction surface 11 has a mean first friction radius 14, and a second contact surface 15 between each friction lining 7, 8 and the second friction surface 12 has a mean second friction radius 16 which differs from the mean first friction radius 14.

[0041] The mean friction radius 14, 16 in each case is present in the middle of a contact surface 13, 15 between the friction lining 7, 8 and the friction surface 11, 12, with the middle being positioned in a radial direction 18, spaced equidistant from an outer radius 26 of the contact surface 13, 15 and an inner radius 27 of the contact surface 13, 15.

[0042] The difference in the mean friction radii 14, 16 is realized by the cutout 17. The cutout 17 is realized on each friction lining 7, 8 to the second friction surface 12, and simultaneously on the second friction surface 12, the second contact surface 15 being reduced by the cutout 17. The cutout 17 is located inward in a radial direction 18 from the mean first friction radius 14. The second contact surface 15, reduced by the cutout 17, extends in the circumferential direction 10 at a constant first radius 20, with one edge 19 bordering on the cutout 17.

[0043] The contact surfaces 13, 15 extend in the radial direction 18 between an outer radius 26 and an inner radius 27. The mean second friction radius 16 is enlarged by the cutout 17, by locating the cutout 17 inside of the second contact surface 15 in the radial direction 18 enlarging the inner radius 27 (relative to the inner radius 27 of the first contact surface 13 of the respective friction lining 7, 8).

[0044] FIG. 5 shows a detail of FIG. 4. See the comments on FIG. 4. Besides the cutouts 17, elevations 28 are also depicted.

[0045] A mean friction radius 14, 16 is increased or reduced by an elevation located within a contact surface 13, 15 on a friction surface 11, 12 and extending at least in the axial direction 3 to the friction lining 7, 8. This elevation 28 is implemented continuously in the circumferential direction 10 (and running along a constant second radius 29). A contact pressure between friction lining 7, 9 and friction surface 11, 12 is intensified by the elevation 28, making it possible to change the mean friction radius 14, 16.

[0046] The elevation 28 is realized here by a bead on the component (plate of the drive side 5 or of the output side 6) forming the friction surface 11, 12.

REFERENCE NUMERALS

[0047] 1 torque limiter [0048] 2 drive train [0049] 3 axial direction [0050] 4 axis of rotation [0051] 5 drive side [0052] 6 output side [0053] 7 first friction lining [0054] 8 second friction lining [0055] 9 pre-stress [0056] 10 circumferential direction [0057] 11 first friction surface [0058] 12 second friction surface [0059] 13 first contact surface [0060] 14 first friction radius [0061] 15 second contact surface [0062] 16 second friction radius [0063] 17 cutout [0064] 18 radial direction [0065] 19 edge [0066] 20 first radius [0067] 21 first drive unit [0068] 22 first drive torque [0069] 23 second drive unit [0070] 24 second drive torque [0071] 25 torsion damper [0072] 26 outer radius [0073] 27 inner radius [0074] 28 elevation [0075] 29 second radius