OVERLOAD CLUTCH

Abstract

A clutch which reacts to torque overload has a ribbed disc which is produced by plastics injection moulding and which is, along its inner or outer periphery, encapsulated in encircling fashion and on both axial side surfaces by an encompassing ring. Said encompassing ring, owing to shrinkage as a result of cooling, enters into static friction engagement with the ribbed disc, and furthermore engages, by means of bevelled flanks, with ribs running radially on at least one of the side surfaces of the ribbed disc.

Claims

1. Clutch which reacts to torque overload, comprising: a ribbed disc which is produced by plastics injection moulding; and a plastic ring which encapsulates the ribbed disc in encircling fashion along an inner or outer periphery of the ribbed disc and on both axial side surfaces of the ribbed disc, wherein the plastic ring is in static friction engagement with said ribbed disc along the inner or outer periphery of the ribbed disc and furthermore engages, by means of bevelled flanks, with ribs running radially on at least one of the side surfaces of the ribbed disc.

2. Clutch according to claim 1, further comprising a collar which runs in coaxially encircling fashion along the inner periphery of the ribbed disc.

3. Clutch according to claim 1, wherein the heights of the ribs, which are oriented in the manner of spokes, taper off in the direction of the outer periphery of the ribbed disc.

4. Clutch according to claim 3, wherein the ribs end with a T-shaped peripheral widening.

5. Clutch according to claim 1, wherein corresponding ribs are provided on both side surfaces of the ribbed disc.

6. Clutch according to claim 1, wherein the ribs have flanks which have a different inclination in one rotational direction of the ribbed disc than in the opposite rotational direction thereof.

7. Clutch according to claim 1, wherein a lubricant is introduced between the ribbed disc and plastic ring.

8. Clutch assembly comprising multiple clutches according to claim 1 cascaded coaxially.

9. Clutch assembly according to claim 8, wherein said multiple clutches, offset coaxially relative to one another, are arranged rotationally conjointly on a central shaft and are surrounded by a hollow shaft or adjacent to a spur gearwheel, which spur gearwheels mesh with spur toothings of the plastic rings.

10. Clutch according to claim 1, wherein either the ribbed disc as a hub is surrounded by the plastic ring, or else the plastic ring as a hub is surrounded by the ribbed disc.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 shows, in an oblique view onto one of its axial side surfaces, the ribbed disc which is profiled with ribs which taper off in ramped or wedge-shaped fashion,

[0016] FIG. 2 shows the ribbed disc from FIG. 1 encapsulated with a viscoplastic encompassing ring to form the overload clutch,

[0017] FIG. 3 shows the ribbed disc encapsulated by the encompassing ring to form a hub, as per FIG. 2, in an enlarged axial longitudinal section,

[0018] FIG. 4 shows a ribbed profile, modified in relation to FIG. 3, on the hub,

[0019] FIG. 5 shows an embodiment radially inverted in relation to FIG. 3, that is to say with the encompassing ring now as a hub, and

[0020] FIG. 6 shows a cascading of multiple overload clutches as per, for example, FIG. 3.

DETAILED DESCRIPTION

[0021] Hereinafter, embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0022] The clutch 11, which reacts reversibly and reproducibly to a predefined torque or generally to torque overload, has a substantially planar ribbed disc 12 which is produced by plastics injection moulding and which has a central hole. Said ribbed disc is, as per FIG. 3, encompassed in U-shaped fashion in axial longitudinal section, likewise by plastics injection moulding, by an encompassing ring 13, specifically is surrounded by a plastic on both of its axial side surfaces 15 and on its face 16 which runs in encircling fashion along the outer periphery 19, which plastic, as a result of intense shrinkage phenomena during the cooling process, enters into adhesive (static friction) engagement with the ribbed disc 12. The ribbed disc 12 thus acts as a hub for this rotating assembly.

[0023] Onto the inner periphery 17 of the ribbed disc 12 there is integrally formed a concentrically encircling, hollow cylindrical collar 18 for the introduction of a torque. In the case of a dimensionally stable inner periphery 17 of the ribbed disc 12, the collar 18 may also be omitted. In practice, the inner periphery of the collar 18 or the inner periphery 17 of the ribbed disc has a non-circular border for the transmission of torques.

[0024] Toward the outer periphery 19 of the ribbed disc 12, spoke-like ribs 20 extend on at least one of the two side surfaces 15 of said ribbed disc. Said profiling is received in complementary fashion by the applied encapsulation of the encompassing ring 13. As a result, in addition to the adhesive (static) friction between the materials of ribbed disc 12 and encompassing ring 13 within the outer periphery 19, positive locking is generated between the two clutch partners in the form of the ribbed disc 12 and the encompassing ring 13. In axial section, the form of a web (in the form of the ribbed disc 12) running in encircling fashion on a flange (in the form of the collar 18 along the inner periphery 17) is realized for example as per FIG. 3.

[0025] Owing to the peripheral number and owing to the radial profile of the axial heights of the ribs 20 and owing to the inclination of the flanks 21 thereof on at least one of the axial disc side surfaces 15, the load-dependent transition from clutch adhesive (static friction) engagement to clutch positive locking can be structurally influenced. If the peripheral rib flanks 21 have a different inclination in one rotational direction of the clutch 11 than in the opposite direction, the reaction of the overload clutch 11 is made dependent on rotational direction in a targeted manner.

[0026] The intense axial shrinkage of the encompassing ring 13 onto the two side surfaces 15 and thus also onto the ribs 20 of the ribbed disc 12, which in FIG. 3 acts as hub, can press the material of said ribbed disc, in the region of the shallow tapering-off of the rib height into the respective side surface 15, to the limit of the load capacity, such that then, owing to softening, the stability required for adhesive (static) friction is lost. The specific pressure load is however reduced to functionally non-critical conditions if, as per the cross-sectional illustration of FIG. 4, the tapering-off of the ribs 20 toward the outer periphery 19 of the ribbed disc 12 is widened in the peripheral direction. In the axial longitudinal section, this results in the profile of a solid rail which runs in encircling fashion around the axis of rotation 22 of ribbed disc 12 and encompassing ring 13; said rail has its web (rib 20) between foot (collar 18) and a rail head in the form of the T-shaped widening 23 in the tapering-off of the rib height to the edge region, which runs in encircling fashion inside the outer periphery 19, of the ribbed disc 12.

[0027] In the variant as per FIG. 5, which is radially inverted in relation to FIG. 3, it is now the case that the encompassing ring 13 is provided as a hub, which is extended through by the axis of rotation 22, of the ribbed disc 12. For this purpose, the inner periphery 17 thereof engages into the encircling, centripetally open U-shaped profile of the encompassing ring 13.

[0028] For the transmission of relatively high torques in a manner protected against overloading, it is expediently the case that multiple clutches 11 of the type described above are cascaded in parallel. Contrary to the diagrammatic illustration of FIG. 6, the individual clutches may be positioned axially directly adjacent to one another if, for example, the axial width of the U yoke on the ribbed disc 12 provides the elastic limbs thereof sufficient axial spreading space at the free face ends thereof which engage between the relatively large rib heights. In the exemplary embodiment depicted in FIG. 6, three clutches 11 are mounted with their ribbed discs 12 rotationally conjointly on a hub shaft 24. A surrounding hollow shaft 25 is equipped with three correspondingly positioned internal gears 26, which mesh with spur toothings 14 of the encompassing rings 13; alternatively, one spur gearwheel of corresponding axial width (not illustrated) meshes therewith. In any case, it is thus the case that each of the three clutches 11 has to be designed only for one third of the torque that is to be transmitted in the selective direction.

[0029] Thus, a clutch 11 which reacts to torque overload has a ribbed disc 12 which is produced by plastics injection moulding as one clutch partner, which ribbed disc is, along its outer periphery 19or, in the case of a central hole, along its inner periphery 17 , encapsulated in encircling fashion and on both axial side surfaces 15 by an encompassing ring 13 as the other clutch partner. Said encompassing ring, owing to shrinkage as a result of cooling, enters into adhesive (static friction) engagement with the ribbed disc 12, and furthermore engages, by means of bevelled flanks 21, with ribs 20 running radially in the manner of spokes on at least one of the side surfaces 15 of the ribbed disc 12. The axial heights of the ribs 20 preferably taper off from a collar 18 along an inner periphery 17 of the ribbed disc 12 in the direction of the outer periphery 19 of said ribbed disc into the respective plane of the side surfaces 15 of said ribbed disc, with axial widening 23. For rotational-direction-dependent opening of the clutch 11, the flanks 21 on both sides of the ribs 20 have different gradients. In the case of such clutches 11 being cascaded coaxially, the torque to be transmitted is distributed across said clutches.

LIST OF REFERENCE DESIGNATIONS

[0030] 11 Clutch [0031] 12 Ribbed disc (of 11) [0032] 13 Encompassing ring (on 15-16-15 of 12) [0033] 14 Spur toothing (of 13) [0034] 15 Side surfaces (of 12) [0035] 16 Face (of 12) [0036] 17 Inner periphery (of 12) [0037] 18 Collar (along 17) [0038] 19 Outer periphery (of 12) [0039] 20 Ribs (on 15) [0040] 21 Flanks (of 20) [0041] 22 Axis of rotation (of 12, 13, 24) [0042] 23 T-shaped widening (of 20 toward 19) [0043] 24 Shaft (in 12) [0044] 25 Hollow shaft (around 13) [0045] 26 Internal gear (in 25, in engagement with 14)