GB2125911A

GB2125911A - Rotary disc for disc brake assembly

Info

Publication number: GB2125911A
Application number: GB08319266A
Authority: GB
Inventors: Hiromasa Okamura; Masahiro Yamada; Michio Akiyoshi
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 1982-07-19
Filing date: 1983-07-15
Publication date: 1984-03-14
Also published as: GB8319266D0; JPS5917035A; GB2125911B; DE3325831A1

Abstract

In a rotary disc 10 of predetermined thickness and diameter arranged to be pressed at its outer peripheral portion 13 by a pair of brake friction pads, a pair of outer peripheral portions 10a, 10a of the disc located on a diametric line L1 are formed lower in their rigidity than the other outer peripheral portion 13 of the disc; such an arrangement is said to prevent occurrence of a standing vibration node. For solid discs, the portions 10a, 10a may be formed by providing radial recesses 13a, 13a, or radial hobs (Figure 3, 4); inserts elements of the same material as the disc may be embedded in the recesses or holes. For discs formed with cooling fins 43a and vent holes 43b, wider spaces ??? between fins (Figure 5), or shorter fins (53 a1, Figure 7) or thinner fins (63 a1, Figure 8) or fins formed with a slit (73 a1, Figure 9) provide the reduced rigidity portions. <IMAGE>

Description

SPECIFICATION Rotary disc for disc brake assembly The present invention relates to a rotary disc of predetermined thickness and diameter for disc brake assemblies which is arranged to be pressed at its outer peripheral portion by a pair of brake friction pads in the brake assembly.

In general, the outer peripheral portion of such a conventional rotary disc as described above is uniformly constructed in its mass and rigidity. For this reason, when the outer peripheral portion of the rotary disc is vibrated at its one point, node and antinode positions in a vibration mode of the rotary disc are determined by the vibrated point and vary in dependence upon change of the vibrated point. This means that such node and antinode positions in the vibration mode of the rotary disc are determined by the assembled position of a brake friction pad which acts to apply a vibration to the rotary disc in braking operation.

In other words, there occurs a standing vibration mode with fixed node and antinode on the rotary disc in braking operation. Such a standing vibration mode results in undesired noises in its resonant frequency. It is also noted that the same standing vibration mode does not occur in all the disc brake assemblies because of occurrence of the undesired braking noises in a close relationship with the whole construction of the disc brake assembly. This means that in many cases there occur a plurality cf standing vibration modes on the same disc brake assembly. For the above reasons, it is required to eliminate such occurrence of all the standing vibration modes so as to effectively decrease the braking noises in all the disc brake assemblies.

It is, therefore, a primary object of the present invention to provide an improved rotary disc for a disc brake assembly in which a pair of nodes or antinodes in all the vibration modes are fixed to rotate integrally with the rotary disc thereby to prevent occurrence of a standing vibration mode of all the diametric nodes.

According to the present invention, the above object is accomplished by provision of a rotary disc wherein a pair of outer peripheral portions of the disc located on a diametric line are formed lower in their rigidity than the other outer peripheral portion of the disc. With the abovedescribed construction in the rotary disc, a node or an antinode in a vibration mode occurs constantly at the pair of outer peripheral portions on the diametric line, and a pair of nodes or antinodes in all the vibration modes are fixed on the diametric line of the rotary disc. For example, in a vibration mode with two diametric nodes, one pair of nodes will occur at a position circumferentially displaced from the other pair of nodes at an angle of 900, and two pairs of antinodes or nodes will be fixed in equidistance.Similarly, in a vibration mode with a number n (n = 3, 4, 5,...) of diametric nodes, one pair of nodes will occur at a position circumferentially displaced in equidistance from another pair of nodes, and n pairs of antinodes or nodes will be fixed in equidistance. The above phenomena have been confirmed in an experiment conducted by the inventors.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a front view of a rotary disc of the solid type in accordance with the present invention; Figure 2 is a sectional view taken along line Il-Il in Figure 1; Figure 3 is a front view of a modification of the rotary disc shown in Figure 1; Figure 4 is a front view of another modification of the rotary disc shown in Figure 1 Figure 5 is a front view of a rotary disc of the ventilation type in accordance with the present invention; Figure 6 is a sectional view taken along line VI--VI in Figure 5; Figure 7 is a front view of a modification of the rotary disc shown in Figure 5;; Figures 8 and 9 illustrate other modifications of the rotary disc shown in Figure 5; and Figure 10 is a sectional view taken along line X-X in Figure 9.

With reference to the accompanying drawings, Figures 1 and 2 illustrate an embodiment of a rotary disc 10 of the solid type in accordance with the present invention. The rotary disc 10 is provided at its hub portion 12 with curcumferentially equi-spaced mounting holes 11 to be attached to a wheel hub (not shown), which disc 10 is arranged to be pressed at its outer peripheral portion 1 3 by a pair of brake friction pads in a conventional disc brake assembly (not shown). The outer peripheral portion 1 3 of disc 10 has predetermined thickness To and diameter D,.

In this embodiment, a pair of outer peripheral portions 1 0a, 1 Oa of disc 10 located on a diametric line L, are formed respectively therein with a radial recess 1 3a of predetermined width t and w1 respectively in its thickness direction and in its circumferential direction and of predetermined depth h1 in its radial direction.

Thus, the pair of outer peripheral portions 1 Oa, 1 Oa on the diametric line L1 are formed lower in their mass and rigidity than the other outer peripheral portion of rotary disc 10 such that a node or an antinode in a vibration mode of disc 10 constantly occurs at the recessed portions 1 Oa, 1 0a. In such construction as described above, a pair of nodes or antinodes in all the vibration modes of disc 10 are fixed at the recessed portions 1 Oa, 1 Oa to rotate integrally with the disc 10 so as to prevent occurrence of a standing vibration mode of all the diametric nodes.

The above useful result has been observed in an experiment of a solid type rotary disc made of cast iron in diameter Do of 204 mm, thickness To of 10 mm, and radial length Ho of 45 mm of the outer peripheral portion 1 3 of the disc. As a result of various change of the relative relationship among width t1, w1 and depth h1 of the radial recess 1 3a in the above experiment, the best result was obtained under the following relationship:: 0.05 6 w1/DO < 0.15 h1/Do > 0.05 t1tr0 < 0.5 In the actual practices of the present invention, as is illustrated in Figure 3, the pair of radial recesses 1 3a, 1 3a in disc 10 of Figure 1 may be replaced with a pair of radial holes 23a, 23a each of inner diameter d2 and radial depth h2 which are formed in a pair of outer peripheral portions 20a, 20a of a solid type rotary disc 20 located on a diametric line L2.Alternatively, as is illustrated in Figure 4, each recess 1 3a in disc 10 of Figure 1 may be replaced with two radial holes 33a, 33a circumferentially spaced in a distance 0 and of inner diameter d3 and radial depth h3 which are formed respectively in a pair of outer peripheral portions 30a, 30a of a solid type rotary disc 30 located on a diametric line L3. In such modifications of the present invention as described above, the optimum value of each dimension d2, h2, d3, h3, 0 is determined on a basis of the actual experiments to effect substantially the same result as that in the rotary disc 10.

Furthermore, in the actual practices of the present invention, an insert element of the same material as that of disc 10, 20 or 30 may be embedded in the radial recess 1 3a, the radial hole 23 or both the radial holes 33a. In such construction, the pair of outer peripheral portions 1 0a, 1 Oa; 20a, 20a; or 30a, 30a of the disc 10, 20 or 30 located on the diametric line L1, L2 or L3 are formed less in their rigidity than the other outer peripheral portion of the rotary disc to effect substantially the same result as that in the rotary disc 10, 20 or 30.Alternatively, in the case that the width t1 of radial recess 1 3a in disc 10 is formed in a smaller value, the pair of outer peripheral portions 1 0a, 1 Oa of disc 10 can be made less only in their rigidity than the other outer peripheral portion of disc 10 without causing decrease of their mass.

In Figures 5 and 6 there is illustrated a rotary disc 40 of the ventilation type in accordance with the present invention. The rotary disc 40 is provided at its hub portion 42 with circumferentially equi-spaced mounting holes 41, which disc 40 is arranged to be pressed at its outer peripheral portion 43 by a pair of brake friction pads in a conventional disc brake assembly. The outer peripheral portion 43 of disc 40 has predetermined thickness T1 and diameter D1 and is provided therein with a plurality of circumferentially spaced radial cooling fins 43a and an even number of circumferentially spaced radial vent holes 43b which are arranged symmetrically in relation to a diametric line L4.

In this embodiment, a pair of circumferential spaces a between radial cooling fins 43a, 43a located along the diametric line L4 are respectively formed to be wider than those p between the other radial cooling fins 43a. Thus, a pair of radial portions 40a, 40a of disc 40 on the diametric line L4 are formed less in their mass and rigidity than the other outer peripheral portion of disc 40 thereby to effect substantially the same result as that in the above-described rotary disc 1 0, 20 or 30.

The present invention may be further adapted to a rotary disc 50 of the ventilation type as is illustrated in Figure 7. In this application, a pair of radial cooling fins 53a1, 53a1 of disc 50 located on a diametric line L5 are formed to be shorter in radial dimension It thereof than that 12 of the other radial cooling fins 53a2. Thus, a pair of radial portions 50a, 50a of disc 50 on the diametric line L5 are formed less in their mass and rigidity than the other outer peripheral portion of disc 50 thereby to effect substantially the same result as that in the above-described rotary disc 1 0, 20, 30 or 40. Alternatively, the present invention may be adapted to a rotary disc 60 of the ventilation type as is illustrated in Figure 8.In the rotary disc 60, a pair of radial cooling fins 63a1, 63a1 located on a diametric line L6 are formed to be thinner in thickness m1 thereof than that m2 of the other radial cooling fins 63a2 thereby to effect substantially the same result as that in the abovedescribed rotary disc 10, 20, 30 or 40.

In a rotary disc 70 of the ventilation type shown in Figures 9 and 10, a pair of radial cooling fins 73a, 73a located on a diametric line L7 are formed respectively therein with a slit 73a1 of predetermined width t2 and radial depth h4 such that a pair of radial portions 70a, 70a on the diametric line L7 are less in their mass and rigidity than the other outer peripheral portion of disc 70.

In the case that the width t2 of slit 73a1 is determined in a smalier value, the pair of radial portions 70a, 70a of disc 70 can be made less only in their rigidity than the other outer peripheral portion of disc 70 without causing decrease of their mass. In the above modifications, the optimum value of each dimension a, I1, m1, t2, h4 is determined on a basis of the actual experiments to effect substantially the same result as that in the rotary disc 10-60.

Claims

1. A rotary disc of predetermined thickness and diameter for a disc brake assembly arranged to be pressed at its outer peripheral portion by a pair of brake friction pads in said brake assembly, wherein a pair of outer peripheral portions of said rotary disc located on a diametric line are formed lower in their rigidity than the other outer peripheral portion of said rotary disc.

2. A rotary disc as claimed in Claim 1, wherein said rotary disc is in the form of a rotary disc of the solid type, and wherein a pair of outer peripheral portions of said rotary disc located on a diametric line are formed respectively therein with a radial recess of predetermined width in its circumferential direction and its thickness direction and of predetermined depth in its radial direction, whereby said pair of outer peripheral portions of said rotary disc being formed lower in their rigidity than the other outer peripheral portion of said rotary disc.

3. A rotary disc as claimed in Claim 1, wherein said rotary disc is in the form of a rotary disc of the solid type, and wherein a pair of outer peripheral portions of said rotary disc located on a diametric line are formed respectively therein with a radial hole of predetermined diameter and depth, whereby said pair of outer peripheral portions of said rotary disc being formed lower in their rigidity than the other outer peripheral portion of said rotary disc.

4. A rotary disc as claimed in Claim 1, wherein said rotary disc is in the form of a rotary disc of the ventilation type provided in its outer peripheral portion with a plurality of circumferentially spaced radial cooling fins and an even number of circumferentially spaced radial vent holes, and wherein a pair of circumferential space between said cooling fins located along a diametric line of said disc are formed to be wider than those between the other radial cooling fins of said disc, whereby a pair of outer peripheral portions of said disc on the diametric line being lower in their mass and rigidity than the other outer peripheral portion of said disc.

5. A rotary disc as claimed in Claim 1, wherein said rotary disc is in the form of a rotary disc of the ventilation type provided in its outer peripheral portion with a plurality of circumferentially spaced radial cooling fins and an even number of circumferentially spaced radial vent holes, and wherein a pair of said radial cooling fins located on a diametric line of said disc are formed to be shorter in radial dimension thereof than that of the other radial cooling fins of said disc, whereby a pair of radial portions of said disc on the diametric line are formed less in their rigidity than the other outer peripheral portion of said disc.

6. A rotary disc as claimed in Claim 1, wherein said rotary disc is in the form of a rotary disc of the ventilation type provided in its outer peripheral portion with a plurality of circumferentially spaced radial cooling fins and an even number of circumferentially spaced radial vent holes, and wherein a pair of said radial cooling fins located on a diametric line of said disc are formed to be thinner in thickness thereof than that of the other radial cooling fins of said disc, whereby a pair of radial portions of said disc on the diametric line are formed less in their rigidity than the other outer peripheral portion of said disc.

7. A rotary disc as claimed in Claim 1, wherein said rotary disc is in the form of a rotary disc of the ventilation type provided in its outer peripheral portion with a plurality of circumferentially spaced radial cooling fins and an even number of circumferentially spaced radial vent holes, and wherein a pair of said radial cooling fins located on a diametric line of said disc are formed respectively therein with a slit of predetermined width and radial depth such that a pair of radial portions of said disc on the diametric line are less in their rigidity than the other outer peripheral portion of said disc.

8. A rotary disc for a disc brake assembly substantially as hereinbefore described with reference to, and as shown in, figures 1 and 2, or figure 3, or figure 4, or figures 5 and 6, or figure 7, or figure 8, or figures 9 and 10 of the accompanying drawings.

9. A disc brake assembly having a rotary disc as claimed in any preceding claim.