CA1163208A

CA1163208A - Disc brake system

Info

Publication number: CA1163208A
Application number: CA000394779A
Authority: CA
Inventors: Takeshi Kawaguchi
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1981-01-24
Filing date: 1982-01-22
Publication date: 1984-03-06
Also published as: DE3202268C2; FR2498712A1; GB2094426B; DE3202268A1; GB2094426A; FR2498712B1

Abstract

ABSTRACT

A shielded disc brake system for motorcycles having means for inducing radial air flow past the brake disc. The device includes an annular passageway between the hub and the shield which may include a centrifugal fan positioned therein. The fan may include passageways between vanes longitudinally aligned with radial passages in the brake disc. The disc itself is mounted about its periphery on bosses extending from the hub. The fan is then bolted to the ends of the bosses to retain the disc from axial movement away from the bosses.
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Description

1 ? ~3~08 DISC BRAKE SYSTEM

BACKGROUND OF T~E INVENTION

The field of the present invention is braking systems and more specifically disc brake systems generally employed with motorcycles.

In conventional disc brake systems for motorcycles, the brake disc is installed on one or both sides of the wheel hub. These discs are generally exposed to open air so that the heat of friction generated during braking is dissipated at a sufficient rate by the movement of the disc or discs through the air.

Either by design choice or responsive to certain intended applications of the brake, the brake disc may be enclosed between the hub and a side panel. The brake is then shielded from dirt, water and the like which generally will reduce wear. In such enclosed systems, ~he enclosure also acts to shield the brake disc from the open air. Consequently, heat dissipation is reduced. Conventionally, such shielded disc brakes have been made larger than the braking require-ments would suggest to reduce the concentration of heat and to increase heat dissipation. Additionally, ventilating of ~he disc itself has been employed to increase dissipation.

~ ~ 6320~, As it is always advantageous to avoid excessive unsprung weight on a vehicle and as it is also advantageous to use small, light components on motorcycles, reduction in the overall size of a disc braking system is considered beneficial. In the event that shielding of a brake disc is also desired, the requirement for larger discs to accommodate the reduced heat dissipation accompanying shielding comes into conflict with the overall goal of reducing component weight.
Thus, increased weight has generally been accepted as an unavoidable liability associated with shielded disc brake designs.
The incorporation of intricate features on the disc such as employed with ventilated discs to increase cooling efficiency also have drawbacks. The disc must necessarily be made of thick metal rather than thin metal in view of head mass considerations. Consequently, the use of even more material in the disc for cooling features is not advantageous for weight considerations. Greater design intricacy also can create problems regarding fabrication and assembly.

Another difficulty associated with brake disks is the mounting of these disks to the hub. When additional cooling features or increased disk diameter are required, it is advantageous to mount the disk at its periphery so that the calipher member may be placed inside to interfere as little as possible with any cooling mechanism or air flow. Further-more, placement of the caliphers on the inside is advantageous on a motorcycle where compact design is important. The earlier mounting design of such externally supported disks requires that the bolts mounting the disk to the hub be placed under substantial stress during braking. Such designs generally require more component parts and have a tendency to prevent J 1 6~2~

the free thermal expansion of the disk in the radially outward direction.
SUMMARY OF T~l~ INVENTION
The pres.ent invention relates to an improved disc brake system for motorcycles of the shielded type which reduces the requirement for the aforementioned substantial increase in weight. To accomplish.this result, improved cooling performance is achieved by the present invention without detracting from the shielding so that the brake discs may be smaller in size, approaching the size of brake discs of comparable unshielded systems.
To accomplish.the foregoing result, the present invention provides a disk brake system for a motorcycle having a wheel hub, said disc brake system including a brake disc fixed on one side thereof to rotate with said hub, a caliper member fixed to the motorcycle for braking engagement with said brake disc, and a side panel covering said brake disc on the other side thereof and having a cooling air introduction port, wherein the improvement comprises means for inducing radial, outward air flow, said air flow inducing means being radially adjacent to the periphery of said brake disc and fixed to rotate with the hub. The air flow inducing means may include a radial flow fan composed of a plurality of vanes annularly spaced outwardly of the disc or simply an annular passage through which air may pass under the influence of the .~

~ ~ 63~08 rotational motion of the disc and the hub. Such additions may be made in light alloy separate from the disc itself.
In association with the employment of a radial flow fan, a ventilated disc may be employed where the radial passage-ways through the disc are aligned with the passageways between vanes. In another aspect of the present invention it is also contemplated that the fan may be employed as a means for locking the disc itself into position on the hub, reducing components and the stresses on same.

Accordingly, it is an object of the present inven-tion to provide an improved disc brake system for motorcycles.
It is a further object to provide a shielded disc brake system which is relatively light in weight and exhibits efficient disc cooling. Other objects and advantages will appear hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a detailed cross-sectional view of a brake disc and mounting boss of the prior art.

Figure 2 is a side view of a first embodiment of the present invention illustrating a motorcycle hub and disc brake system.

Figure 3 is a cross-sectional view taken along line 3-3 of Figure 2.

Figure 4 is a side view of a second embodiment of the present invention.

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Figure 5 is a cross-sectional view taken along line 5-5 of Figure 4.
Figure 6 is a side view of a third embodiment of the present invention.
Figure 7 is a cross-sectional view taken along line 7-7 of Figure 6.
Figure 8 is an embodiment similar to that of Figures 6 and 7 but for the front rather than rear wheel of a motorcycle and incorporating dual discs.
Figure 9 is a side view of a fourth embodiment of the present invention.
Figure 10 is a cross-sectional view taken along line 10-10 of Figure 9.

DETAILED DESCRIPTION OF T~E PREFERRED EMBODI~ENT
An earlier mounting design for externally supported disks is illustrated in Figure 1 of the drawings. In Figure 1, a brake disk a is fixed to a mounting boss b on the hub by means of a rod or bolt c extending through a mounting hole d in the brake disk a. An enlarged mounting boss e on the brake disk a was employed to meet with the mounting boss b through which the bolt c passed. The prior art device illustrated in Figure 1 requires that the bolt c be placed under substantial stress during braking.
Turning in detail to the drawings, Figures 2 and 3 illustrate the rear wheel assembly of a motorcycle including a rear fork assembly 10, a rear wheel axle 12 and a rear wheel hub 14. The hub 14 is supported by the rear fork assembly 10 and rotatably mounted about the rear wheel axle 12 and a bearing 16. As can best be seen in Figure 3, a final drive flange 18 is fixed to the hub 14 and includes a driven sprocket 20 bolted to the final driven flange 18 by bolts 22.

~ 1 63~08 On the side of the hub 14 opposite the driven sprocket 20 is a disc brake system including a brake disc 24. The brake disc 24 is mounted at its outer periphery to the hub 14. Three sets of mounting projections ~6 and 28 define cutout portions between the pro3ections of each set.
The wheel hub 14 includes three bosses 30 which extend laterally toward the brake disc 24 to engage the sets of mounting projections. The fit between the disc 24 and the bosses 30 is loose to accommodate thermal expansion.

Mounted to the rear fork assembly 10 is a caliper member 32. The caliper member is fixed against rotating with the hub 14 and brake disc 24; and includes pads 34 and 36 positioned on either side of the brake disc 24. These pads may be forced into braking engagement with the brake disc 24 upon operation of a caliper piston 38 in a conventional manner. The caliper member spans the disc from the inside for compactness and to avoid interference with disc cooling.

The disc brake system includes a side panel 40 which covers the side of the brake disc 24 away from the hub 14. The side panel 40 extends radially outwardly to adjacent the periphery of the brake disc 24. The hub 14 also extends by means of a flange 42 to adjacent the outer periphery of the brake disc 24. Thus, an annular slearance or passageway is defined between the flange 42 of the hub 14 and the outermost extension of the side panel 40. The surround-ing of the brake disc 24 by the hub 14 and its flange 42 and by the side panel 40 prevents the deposit of water, dust and the like on the brake disc.

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1 1 ~320~

To promote cooling of the braking system which is subject to frictional heating during use of the brakes, cool-ing air introduction ports 44 are provided through the side panel 40 inwardly of the brake disc 24. These cooling air introduction ports are positioned such that incoming air will flow radially outwardly past the brake disc 24 as can be seen by the arrows in Figure 3.

A centrifugal or radial flow cooling fan 46 is positioned radially adjacent to the periphery of the brake disc 24. In the embodiment of Figures 2 and 3, the cooling fan is integral with the hub 14 and includes a plurality of vanes 48 which may be arranged for maximum induced radial flow through the annular passageway. In the embodiment of Figures

2 and 3, the vanes 48 are integrally formed with the flange 42 of the hub 14. Rotation of the hub 14 by the driving of the motorcycle will cause the vanes 48 to act as a means for inducing radial, outward air flow in a manner consistent with a centrigugal fan. To a certain extent, the mere existence of the annular passageway adjacent the periphery of the brake disc 24 in combination with both the rotation of the brake disc 24 and of the hub 14 and ~associated flange 42 will create or induce air flow from the cooling air introduction ports, past the brake disc 24 and between the extremities of the side panel 40 and the wheel hub flange 42.

A shroud or ring 50 is positioned about the fan 46 to close the distal ends of the vanes 4~. This shroud or ring 50 is fixed by fasteners 52 to the mounting bosses 30 of the hub 14. The placement of the ring 50 retains the brake disc ~ 1 ~320~s 24 in its axial position. The sets of mounting projections 26 and 28 retain the brake disc 2~ from rotational movement.
Thus, the brake disc is securely positioned in place. The mounting of the brake disc including the mounting projections 26 and 28 about the bosses 30 and the retaining ring or vane shroud 50 is unlike the prior art illustrated in Figure 1.
In the preferred embodiment of the present invention, the mounting projections 26 and 28 provide integral loading on the brake disc 24 rather than through a bolt shaft as in the prior art.

Looking next to the embodiment of Figures 4 and 5, similar reference numeral-s are employed to designate identi-cal or substantially identical components to those of the embodiment of Figures 2 and 3. The additional feature presented in the embodiment of Figures 4 and 5 is the employment of a ventilated brake disc 24. The ventilated brake disc includes radial passages 54 extending centrally through the brake disc 24. Webs 56 separate the passages 54 and help to strengthen the disc. The embodiment~of Figures 4 and 5 further illustrate the iongitudinal alignment of the vanes 48 with the webs 56 to create relatively continuous flow paths through the brake disc 24 and through the fan 46.

The embodiments of Figures 6, 7 and 8 also employ corresponding numbers to the earlier embodiments. In Figures 6 and 7j a rear wheel for a motorcycle is disclosed as in the prior embodiments. In Figure 8, the same air flow scheme is employed on a front wheel device employing dual brake disc 24.
Front forks 58 are thus employed in the embodiment of Figure 8.

~ ~ 632Q~

The means for inducing radial air flow in the embodiment of Figures 6 through 8 is simply the presence of a space between the flange 42 of the hub 14 and the side panel 40. Furthermore, the rotation of the disc 24 and of the hub 14 induce flow from the cooling air introduction ports 44 in a radially outward direction through the passage-way between the hub and the side panel. A ring 50 is again bolted to the mounting bosses 30 but does not form a shroud for any vanes of an annular fan.

Looking then to the embodiment of Figures 9 and 10, corresponding numbers are again employed. In this embodiment, the vanes 48 are integrally associated with the shroud and__~
mounting ring 50. The flange 42 extending from the hub 14 to adjacent the periphery of the disc 24 includes an additional segment extending adjacent the side of the vanes 48 as can best be seen in Figure 10. By separately forming the fan, the fan may be of any appropriate material rather than the specific light alloy of the hub.

Thus, through the embodiments of the present inven-tion disclosed above, both weight and size reduction can be achieved with shielded disc brake systems without compromising cooling requirements. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifica-tions are possible without departing from the inventive concepts I 1 6320~s herein described. The invention, therefore, is not to be restricted except by the spirit of the appended claims.

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Claims

What is Claimed is:

1. A disc brake system for a motorcycle having a wheel hub, said disc brake system including a brake disc fixed on one side thereof to rotate with said hub, a caliper member fixed to the motorcycle for braking engage-ment with said brake disc, and a side panel covering said brake disc on the other side thereof and having a cooling air introduction port, wherein the improvement comprises means for inducing radial, outward air flow, said air flow inducing means being radially adjacent to the periphery of said brake disc and fixed to rotate with the hub.

2. The disc brake system of claim 1 wherein said air flow inducing means includes a radial flow fan.

3. The disc brake system of claim 1 further com-prising a flange on the hub extending to adjacent one side of the periphery of said brake disc and wherein said side panel extends to adjacent the other side of the periphery of said brake disc, said air flow inducing means being the annular passageway defined between the extensions of said side panel and said flange.

4. The disc brake system of claim 3 wherein said air flow inducing means further includes a fan located in said annular passageway about the periphery of said brake disc.

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5. The disc brake system of claim 1 wherein said air flow inducing means includes a radial flow fan having a plural-ity of vanes radially adjacent to said brake disc.

6. The disc brake system of claim 5 wherein said plurality of vanes are fixed to the hub and said fan further includes a shroud, said shroud being radially adjacent the periphery of said side panel.

7. The disc brake system of claim 1 wherein said brake disc includes radial passages therethrough defining a plurality of webs therebetween.

8. The disc brake system of claim 7 wherein said air flow inducing means includes a radial flow fan having a plurality of vanes radially adjacent said brake disc, said vanes being longitudinally aligned with said webs.

9. The disc brake system of claim 1 further com-prising a plurality of bosses fixed to the motorcycle hub and extending toward said brake disc, said brake disc having cutout portions for receipt of said bosses, said air flow inducing means including a ring fixed to the ends of said bosses on the other side of said brake disc from the hub to retain said brake disc on one side of the hub.

10. The disc brake system of claim 9 wherein said ring includes a radial flow fan.

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