BRAKE DISC COMPRISING A FRICTION RING AND A HUB PRODUCED AS A SEPARATE ELEMENT AND ARRANGED INSIDE OF THE FRICTION RING

Abstract

A brake disc having a friction ring and a hub produced as a separate element and arranged inside the friction ring according. Recesses are configured in the friction ring on the inside to connect the hub to the friction ring and corresponding projections are formed on the hub, which projections engage in the recesses of the friction ring in order to be able to transfer torque from the friction ring to the hub. The recesses have an undercut at least partially in a radial direction, as viewed looking inward from the outside. The disc is simple and cost-effective to manufacture and has an acoustically advantageous operating performance, in particular in the case of thermal expansion.

Claims

1. A brake disc comprising: a friction ring; a hub formed as a separate element and arranged inside the friction ring; at least two recesses formed in an inner circumference of the friction ring to connect the hub to the friction ring; and at least two projections formed on the hub that engage with the recesses of the friction ring to transfer torque from the friction ring to the hub, wherein the recesses have an undercut at least partially in a radial direction from an outer circumference of the friction ring towards the inner circumference.

2. The brake disc according to claim 1, wherein the recesses formed in the friction ring and the corresponding projections formed in the hub are configured such that a thermal expansion due to the geometries of the recesses and the projections on the friction ring in the area of the recesses produces a force acting inward at least partially in the radial direction.

3. The brake disc according to claim 1, wherein the friction ring is fixed relative to the hub against expansion in the radial direction solely by the undercut and/or by a force produced by the thermal expansion and acting at least partially radially inward.

4. The brake disc according to claim 1, wherein the recesses have at least in part a contour continuous in side view, an arcuate contour, polygonal contour, and/or cycloid-shaped contour.

5. The brake disc according to claim 1, wherein the friction ring has an inner side with arcuate sections, wherein the recesses extend radially outward from the arcuate sections, and wherein the recesses at least in part have at least one region that is further outward as viewed in the radial direction and in which the recess is broader in the circumferential direction than in the area of the arcuate section.

6. The brake disc according to claim 1, wherein at least three recesses with undercuts are formed in the friction ring and at least three corresponding projections, engaging in the area of the undercuts, are formed in the hub.

7. The brake disc according to claim 1, wherein the hub comprises a circular inner region and an outer region, extending at least partially in the axial direction from the inner region, and wherein the projections are formed in the outer region.

8. The brake disc according to claim 1, wherein the friction ring and the hub are made of different materials.

9. The brake disc according to claim 1, wherein the recesses and/or the projections are formed using a tool that is moved at least partially on a hypocycloid curve.

10. The brake disc according to claim 1, wherein the hub is produced as a cast part or forged part and is finished mechanically by turning and/or milling.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0019] FIG. 1 shows a schematic illustration of an embodiment of a brake disc of the invention in a side view;

[0020] FIG. 2 shows the area, labeled with II in FIG. 1, in an enlarged illustration;

[0021] FIG. 3 shows a perspective illustration of an embodiment of a brake disc of the invention in an exploded illustration;

[0022] FIG. 4 shows the brake disc of the invention, shown in FIG. 3, in the assembled state in a side view;

[0023] FIG. 5 shows the area, labeled with V in FIG. 4, of the brake disc in an enlarged illustration; and

[0024] FIG. 6 shows an alternative design of a brake disc of the invention in the area of a projection of a hub and a recess of a friction ring similar to the illustration in FIG. 5.

DETAILED DESCRIPTION

[0025] FIG. 1 shows a first embodiment of a brake disc 10 of the invention. Brake disc 10 comprises a friction ring 12 having an outer side 14, which is circular in side view, and an inner side 16, which comprises alternately arcuate sections 18 and recesses 20 extending in the radial direction r.

[0026] On the inside of friction ring 12, a hub 22 is disposed whose outer side 24 in the illustrated embodiment is formed complementary to inner side 16 of friction ring 12. Friction ring 12 has projections 32 formed complementary to recesses 20.

[0027] FIG. 2 shows an enlarged illustration of friction ring 12 in the area of a recess 20 together with the complementarily formed hub 22. It is clearly evident in this figure that recess 20 has an undercut in the area of inner side 16 of friction ring 12 in the radial direction as viewed looking inward from the outside (i.e., oriented toward center M of brake disc 10). This means that the contour narrows from point 26 of recess 20, said point being outermost as viewed looking outward in the radial direction, to arcuate sections 18 at at least one place. In the embodiment shown in FIG. 2, the width increases in the radial direction, as viewed looking inward from the outside, up to the area labeled with b.sub.R,max and then decreases from this area in the radial direction, as viewed looking inward from the outside, up to the area labeled with b.sub.R,inner. The terms b.sub.R,max and b.sub.R,inner here stand for the arc lengths b in the area of arcuate sections 18 or in the area with the greatest extent of recess 20 in the circumferential direction. Region 30, extending in the radial direction, between the arcuate area b.sub.R,max and b.sub.R,inner is an undercut in the context of the invention.

[0028] If there is an operational heating of friction ring 12 of brake disc 10, in particular due to the friction of brake pads coming into contact with friction ring 12, this has the result that brake disc 10 expands in the radial direction according to arrow 28 in relation to hub 22. Hub 22 typically heats up less greatly and, for reasons of saving of weight, often consists of a material with a lower coefficient of thermal expansion. Both of these circumstances, independently of one another, have the result that friction ring 12 upon heating moves outward in the radial direction and therefore the distance between outer side 24 of hub 22 and inner side 16 of friction ring 12 increases.

[0029] In FIG. 2, b.sub.T,max designates the maximum extent (arc length) of hub 22 in the area of projection 32, shown in FIG. 2, in the circumferential direction. Said arc length b.sub.T,max in the shown embodiment is designed such that it is greater than the arc length b.sub.R,inner in the area of arcuate sections 18, if friction ring 12 and hub 22 are at ambient temperatures (typically between −30° C. and +50° C.).

[0030] This assures that in the case of an increasing thermal expansion, friction ring 12 due to the undercut can only move so far radially outward until projections 32 come to rest against recesses 20 in the undercut area. A further heat input in friction ring 12 has the result that projections 32 deform with friction ring 12.

[0031] FIGS. 3 to 5 show a second embodiment of a brake disc 10 of the invention. The same reference characters as in FIGS. 1 and 2 are used hereafter for identical or at least functionally equivalent elements of this embodiment.

[0032] The embodiment shown in FIGS. 3 to 5 differs substantially in the geometric design of projections 32, which can be clearly seen in FIGS. 3 and 5 and are formed on hub 22. These have a linear outer contour on their outer side. Side, arcuate outer contours, which are formed with a hypocycloid shape, join this linear outer contour.

[0033] Further, hub 22, as is evident in FIG. 5, has an inner region 34 and an outer region 36 extending in the axial direction opposite to inner region 34. Projections 32 are formed spaced apart from inner region 34 on outer region 36 and form the outermost boundary of hub 22 as viewed in the radial direction. Inner region 34 has a plurality of circular recesses for screwing hub 22 to a wheel hub.

[0034] FIG. 6 shows an alternative design of a brake disc 10 of the invention in the area of a projection 32 of a hub 22 and a recess 20 of a friction ring 12 similar to the illustration in FIG. 5. In this embodiment, b.sub.R,max is outside projection 32.

[0035] In the exemplary embodiments, a thermal expansion of friction ring 12 results in one or more contact areas between recesses 20 of friction ring 12 and projections 32 of hub 22 in a region formed in a radial direction between the areas designated with b.sub.R,max and b.sub.R,inner in FIGS. 2, 5, and 6. In these areas, a radially at least partially internally directed restoring force is achieved, which increases with an increasing thermal expansion.

[0036] A contact point K and a restoring force R acting on this point are identified in FIG. 2 by way of example.

[0037] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.