DE3800502A1 - Brake disc for disc brakes - Google Patents

Abstract

The invention relates to a brake disc for disc brakes with a friction-disc body which has two brake-ring discs which are arranged at an axial distance from one another and between which there are enclosed cooling-air ducts. The object is to ensure that, as regards the increase in temperature which it undergoes during braking, the brake disc should behave in such a way that the braking torque remains substantially constant. This is achieved by virtue of the fact that the axes of the cooling-air ducts, the latter being arranged radially relative to the axial direction of the disc, lie on a common cone envelope. This ensures that unequal quantities of heat in the radial direction are absorbed at the two brake-ring discs during braking, counteracting the formation of disruptive differences in thickness in the friction-disc body. The direction in which the tip of the cone, which lies on the disc axis, should point and the thickness of the brake-ring discs depends on the type of brake (fixed-calliper, floating-calliper or frame-type calliper disc brake).

Description

The invention relates to a brake disc for discs brake, especially of motor vehicles, with the Features of the preamble of claim 1.

With a brake disc of this type (DE-PS 19 50 178) is the wall thickness of each brake ring disc of its friction disc body continuously in the radial direction the same, but not on the rotating carrier bound brake ring disc the smaller wall thickness points. The featured between the two brake ring discs seen cooling air channels extend in one Radial plane.

With this construction it was possible to achieve that Thermal stress cracks only after a long service life and extraordinary stress occur. Indeed can change due to certain operating conditions of successive decelerations and that emerging operating temperatures on the friction surface the brake ring disks by running parallel to the circumferential direction wavy warp, train.  

If such axial runouts occur on both frictions Develop areas differently, this can local thickness errors or differences in thickness of the friction lead body, which during the passage between the one pressed against the friction surfaces during braking Brake pads by moving the same a change (increase-decrease) of the the brake pads acting hydraulic brake pressure cause.

Resulting from such a changing pressure curve a lot during one revolution of the brake disc of changes in the effective braking torque at appropriate intensity cause of vehicle vibrations could be.

It is therefore an object of the invention to provide a brake disc in training according to the preamble of the patent saying 1 to improve so that this when braking shows a behavior during their warming that one largely constant braking torque guaranteed.

This object is achieved by the kenn Drawing features of claim 1 solved.

The brake disc according to the invention tapers thus the wall thickness of their two brake ring disks in radially opposite directions what at Brakes on the friction disc body on its brake ring discs in the radial direction to an asymmetrical heat recording leads to this dynamic behavior  imprints the thickness of the formation which is disruptive counteracts.

With regard to the respective brake type (fixed caliper, Floating saddle or frame saddle) is empirically too determine whether the tip of the cone, on its shell the axes of the cooling air ducts lie in the direction of the Wheel wrench of the wheel to be braked or opposite to it should point. You must also determine which channel angle of inclination is the most favorable, with a Nei angle between 4 and 8 ° has proven to be advantageous Has.

Advantageous embodiments of the invention are counter stood by subclaims.

Exemplary embodiments of the invention are shown in the drawing shown. Show it:

Figs. 1 to 3 are respectively a longitudinal section Inventions embodied according brake discs.

The brake disks according to the drawing have a friction disk body designated as a whole as 10 , which is equipped with two brake ring disks 12 and 14 arranged at an axial distance from one another. These each have an outer flat friction surface 16 and 18 , which are arranged parallel to each other and normal to the disc axis 19 .

The distance between the two brake ring disks 12 and 14 is bridged by equally spaced connecting webs 20 which rigidly connect them to one another. Both Bremsringschei ben 12 and 14 and the connecting webs 20 include between them cooling air channels 22 which, for example, have a substantially square cross section and, seen in the axial direction of the brake disc, run radially ver.

On the inner circumference of the brake ring disk 14 , for example, a pot-shaped fastening part 24 is formed, for which purpose this is connected to the brake ring disk 14 via an outer flange 26 (FIGS . 1 and 2).

As shown in FIG. 1, the cooling air channels 22 are inclined within the friction disc body 10 at a constant inclination angle α for all, the longitudinal axis of these cooling air channels 22 lying on a cone jacket 28 of a blunt cone 30 . In the embodiment according to FIG. 1, the cone tip 32 lying on the disc axis 19 is trimmed in front of preferably in the direction of the cup-shaped fastening part 24, and indeed this construction has a combination of the brake disc with a disc brake having a fixed caliper, with regard to the connection the brake washer 14 on the outer flange 26 of the cup-shaped fastening part 24 , to achieve mini mated braking torque fluctuations as advantageous, he pointed out.

The arrangement of the cooling air ducts 22 in the specified direction of inclination has the result that the brake ring disc 14 connected to the fastening part 24 on the outer circumference side and the non-connected brake ring disc 12 have the greatest wall thickness on the inner circumference side.

Both brake ring disks 12 and 14 are, seen in longitudinal section, wedge-shaped and preferably have in opposite directions substantially the same taper and Keilab measurement.

When the brake pads engage with the friction surface 16 or 18 next to them, the brake ring disks 12 and 14 will therefore store the greatest amount of heat in the area of their larger thicknesses and thus the temperature profile of the pot-side brake ring disk 14 will show the maximum surface temperature radially on the outside and that of the not connected brake disc 12 reach the maximum surface temperature radially inside.

For the special type of disc brake (fixed caliper brake), this causes thermal expansions in the brake disc, which ensures that the friction surfaces 16 and 18 of the friction disc body 10 are largely flat, even during subsequent braking, by the friction surfaces 16 and 18 correspondingly remaining free of distortion.

The brake disk according to FIG. 2 is designed for such a type of disc brakes, wherein it has been found that internally to maintain the desired axial run of the friction surfaces 16 and 18 of their Reibscheibenkörpers 10 and outside thickness dimensions annular discs its brake 12 and 14 are required which are provided in reverse to those of the brake ring disks 12 and 14 of the construction according to FIG. 1. Accordingly, the cooling air channels 22 are inclined with a constant inclination angle α for all, the longitudinal axis of which lies on a jacket 40 of an obtuse cone 42 , the cone tip 44 of which lying on the disc axis 19 is directed away from the cup-shaped fastening part 24 .

In this case, on the one hand, the radially inner part of the brake ring disc 14 connected to the fastening part 24 and, on the other hand, the radially outer part of the brake ring disc 12 when braking, the largest amounts of heat, whereby the frictional heat on the runout of the friction surfaces 16 and 18 remains largely ineffective.

Is shown in FIG. 3, a cup-shaped attachment member connected 46 via an outer flange 48 on the inner circumference of the inside brake ring disc 12, a configuration is the brake disk body 10 according to FIG. 2, also for a disc brake, the brake shoes, in analogy to the construction of Fig. 1, in a fixed saddle are installed. One of the reasons for this is that in both cases the smaller wall thickness of the brake ring disk 12 or 14 in question ( FIG. 1) in the area of the outer flange 26 or 48 of the fastening part 24 or 46 respectively causes the smaller amount of heat to fall and thereby the maximum surface temperature at a radial distance from the outer flange 26 or 48 arises, which also has a correspondingly advantageous effect on the shielding behavior of the friction disk body 10 .

Claims (6)

1. Brake disc for disc brakes, in particular of motor vehicles, with a friction disc body, which has two axially spaced brake ring discs of different thicknesses, one of which can be fastened to an inner part on a circumferential carrier and both have an outer, axially normal friction surface and Are connected to one another via connecting webs, between which, seen in the axial direction of the discs, radial cooling air ducts are included, characterized in that the axes of the cooling air ducts ( 22 ) lie on a common conical jacket ( 28 ; 40 ). 2. Brake disc according to claim 1, characterized in that the outer and inner circumferential thickness dimensions of one brake ring disc ( 12 ) substantially correspond to the thickness dimensions on the other disc circumference of the adjacent brake ring disc ( 14 ). 3. Brake disc according to claim 1 or 2, characterized in that the inner part ( 24 ; 46 ) of the brake ring disc ( 14 ) which can be fastened to the circumferential carrier is formed in a pot shape. 4. Brake disc according to claim 3, characterized in that the cup-shaped inner part ( 24 ; 46 ) having the brake ring disc ( 14 or 12 ) has the smaller wall thickness radially inside. 5. Brake disc according to claim 4, characterized in that the outside brake ring disc ( 14 ) on the pot-shaped inner part ( 24 ) is connected. 6. Brake disc according to claim 4, characterized in that the inner brake ring disc ( 12 ) on the pot-shaped inner part ( 46 ) is connected.