GB2286438A - A brake disk of a disk brake for high-performance cars - Google Patents

Description

2286438 "A brake disk of a disk brake for carsit high-performance This

invention relates to a disk brake for high-performance cars, being of a type which comprises an annular braking band formed of two ring plates defining an interspace therebetween.

Disk brakes, especially those equipping high-performance cars, can occasionally become a source of loud noise in the form of an objectionable whine, which obviously detracts from driving comfort.

Due to the random character of the vibratory phenomena that are at the root of the noise emission in its varying aspects, it had not been possible to remedy this inconvenience heretofore.

The underlying problem of th.is invention is to provide a brake disk as above, which has such structural and functional features as to overcome said shortcoming.

The invention has been arrived at as a result of the observation that the noise emission is due to the onset of a vibration-in the braking band whereby the band enters a condition of circumferential waviness.

Based an this finding and to solve said 1 technical problem, this invention provides a brake disk as indicated, which is characterized in that the braking_ band comprises a plurality of projections facing into the interspace and being distributed at pitch distances circumferentially across said band.

Further features and the advantages of a brake disk according to the invention will be apparent from the following description of an embodiment thereof, given by way of non-limitative example with reference to the accompanying drawing, in which:

Figure 1 is a perspective view of a brake disk according to the invention; Figure 2 is a detail view of the brake disk in Figure 1, taken in the direction of arrow II; Figure 3 is a sectional view of the detail shown in Figure 2, taken along line III-III; and Figure 4 is a sectional view of the detail as in Figure 2, but taken along line IV-IV.

With reference to the drawing views, generally shown at 1 is a brake disk of a disk brake particularly intended for high-performance cars.

The brake disk 1 comprises an annular braking band 2 having an axis X-X and an outside diameter of 316 mm in this example. The band 2 is a cast iron piece formed of two ring plates 3 and 4 which are laid 1 C_ A side-by-side and spaced apart concentrically with the axis X-X.

The ring plates 3 and 4 define an interspace therebetween, and are interconnected by a plurality of substantially radial wings 6, thirty six in this example, which are distributed at pitch distances circumferentially across the band. A bell-shaped piece 7 is rigid with the ring plate 3 for mounting the disk 1 on a hub, not shown, of a road wheel of the motor vehicle.

Defined in the interspace 5 between each pair of adjacent wings is a substantially radial passageway 8 through which a flow of cooling air is established in operation.

In the brake disk 1 of this invention, the band 2 has a plurality of projections 9 facing into the interspace 5 and being distributed at pitch distances circumferentially across the band close to the periphery of the latter.

Preferably, the projections 9 are arranged in two tiers, 10 and 11, with the projections of the tier 10, denoted by 9a, extending from the ring plate 3, and the projection of the tier 11, denoted by 9b, extending from the ring plate 4.

The projections ga and 9b are offset from one - 4 another.

In this example, there are provided twenty four projections 9, including twelve projections 9a and twelve projections 9b.

The projections 9a locate in respective passageways 8 and are interposed between adjacent pairs of wings 6 to occupy one passageway every two. The wings 9b are instead aligned to respective ones of the plurality of wings 6, at one wing every two.

The projections 9a are teardrop shaped with a convergent tip 12 in the direction toward the axis X-X. As for the projections 9b, although crossed by respective wings, these also have a teardrop shape, with a virtual tip 12b convergent in the direction toward the axis X-X.

The projections 9 are cast in and have a predetermined cross-sectional area, e.g. of 1.1 cm, and predetermined height, e.g. of 8 mm. Accordingly, they will have a predetermined volume, and hence a predetermined mass, of about 6.4 g in the example.

The number of the projections 9 is selected to be the same as the number of the half-waves in the wavy pattern into which the brake disk of the claim preamble used to settle at the time of emitting the whining noise.

m - 5 This number can be readily found as follows. The various vibration own modes of the braking band are first figured out, and then the various wavy patterns that it can consequently take along with the respective own frequencies. Thereafter, the frequency of the vibration that actually occurs is measured using appropriate instruments.

The number of the projections will be the same as that of the half-waves in the wavy pattern whose own frequencies more closely approach the measured frequency.

A major advantage of the inventive brake disk resides in the quiet brake application that it brings about.

it is also simple to fabricate, a non-negligible advantage with an article which is to be mass produced.

In addition, this brake disk has shown to undergo reduced heating.

It will be appreciated that many changes and modifications may be made unto the brake disk described by skilled persons in the art in order to fill contingent and specific demands, all of which are, however, encompassed by the protection scope of the following claims.

Claims (3)

1. A brake disk of a disk brake for high-performance cars, being of a type which comprises an annular braking band formed of two ring plates defining an interspace therebetween, wherein the braking band comprises a plurality of projections facin.c into the interspace and being distributed at pitch distances circumferentially across said band.

2. A brake disk according to Claim 1, wherein the projections are split into two tiers, the projections of each tier jutting out from a respective one ofthe ring plates and being offset from the projections of the other tier.

3. A brake disk substantially as hereinbefore described with reference to the accomnanyinq drawinqs.

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