GB2105804A

GB2105804A - Disc brake apparatus

Info

Publication number: GB2105804A
Application number: GB08220728A
Authority: GB
Inventors: Takeshi Kawaguchi
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1981-07-17
Filing date: 1982-07-16
Publication date: 1983-03-30
Also published as: GB2105804B

Abstract

A disc brake apparatus for a motorcycle having a wheel hub 14, comprising a brake disc 24 fixed to rotate with said hub, a caliper member 32 fixed to the motorcycle for braking engagement with said brake disc, a side panel 40 covering said brake disc on the other side of said disc from the hub and including at least one cooling air introduction port 64, means 60 radially adjacent the periphery of said brake disc for inducing radially outward flow of said cooling air, and screening means 68, 72 across said cooling air introduction port and/or said air flow inducing means. <IMAGE>

Description

SPECIFICATION Disc brake apparatus This invention relates to disc brake apparatus for motorcycles.

In conventional disc brake systems for motorcycles, a 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 to generally reduce wear. In such enclosed systems, the 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 requirements would suggest to reduce the concentration of heat and to increase heat dissipation.

Additionally, ventilating of the disc itself has been employed to increase dissipation.

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 overail 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 has drawbacks. The disc must necessarily be made of thick metal rather than thin metal in view of heat 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.

Viewed from one aspect the present invention provides a disc brake apparatus for a motorcycle having a wheel hub, comprisng a brake disc fixed to rotate with said hub, a caliper member fixed to the motorcycle for braking engagement with said brake disc, a side panel covering said brake disc on the other side of said disc from the hub and including at least one cooling air introduction port, means radial ly adjacent the periphery of said brake disc for inducing radially outward flow of said cooling air, and screening means across said cooling air introduction port and/or said air flow inducing means.

Viewed from another aspect the invention provides a disc brake apparatus for a motorcycle having a wheel hub, comprising 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 braking disc, a side panel covering said brake disc on the other side of said brake disc from said hub and defining an annular opening between said side panel and the hub radially adjacent to the periphery of said brake disc, and a cover fixed to said side panel and extending across said annular opening, said cover including annularly disposed apertures therethrough.

In a preferred form the present invention contemplates means for inducing radially outward air flow about the periphery of the brake disc between the hub and a side panel. This 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 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 passageways through the disc are aligned with the passageways between vanes. 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.

To further protect the disc and caliper assembly, screening means may be fixed about the periphery of the disc such as at the roots of the fan blades or covering apertures disposed in an annular arrangement outwardly of the disc. Additionally, screening means may also be employed over the inlet ports to keep out additional dirt. If large pieces of dirt and debris are allowed to enter the inlet ports, it could become trapped within the peripheral screen. This can be avoided with appropriate screening material on the inlet ports. Such material for both locations may be either mesh or perforated plate.

Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a sisde view of a first embodiment of the present invention.

Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1.

Figure3 is a side view of a second embodiment of the present invention.

Figure 4 is a cross-sectional view taken along line 4-4 of Figure 3.

Figure 5 is a detail view of apertures in an annular portion of the brake shield.

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 explosed perspective view of a simplified side panel illustrating the screening material of Figures 6 and 7.

Turning in detail to the drawings, Figures 1 through 8 illustrate the front wheel assembly of a motorcycle including a front fork assembly 58, a front wheel axle 12 and a front wheel hub 14. The hub 14 is supported by the front fork assembly 58 and is rotatably mounted about the front wheel axle 12 and a bearing 16.

On each side of the hub 14 there 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 26 and 28 define cutout portions between the projections 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 front fork assembly 58 are caliper members 32. The caliper members are fixed against rotating with the hub 14 and brake discs 24; and include pads 34 and 36 positioned on either side of each brake disc 24. These pads may be forced into braking engagement with the brake discs 24 upon operation of caliper pistons 38 in a conventional manner. The caliper members span the discs from the inside for compactness and to avoid interference with disc cooling.

Each 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 surrounding of the brake disc 24 by the hub 14 and by the side panel 40 prevents the deposit of water, dust and the like on the brake disc.

A centrifugal or radial flow cooling fan is positioned radially adjacent to the periphery of the brake disc 24. In the embodiment of Figures 1 and 2, the cooling fan is integral with a shroud 62 and includes a plurality of vanes 60 which may be arranged for maximum induced radial flow through the annular passageway. Rotation of the hub 14 by the driving of the motorcycle will cause the vanes 60 to act as a means for inducing radial, outward air flow in a manner consistent with a centrifugal fan. To a certain extent, the mere existence of the annular passageway adjacent the periphery of the brake disc 24 and of the hub 14 will create or induce airflow past the brake disc 24 and between the extremities of the side panel 40 and the wheel hub 14.

The shroud 62 is positioned about the fan to close the distal ends of the vanes 60. This shroud 62 is fixed by fasteners 52 to the mounting bosses 30 of the hub 14. The placement of the shroud 62 retains the brake disc 24 in its axial position. The sets of mounting projections 26 and 28 retain the brake disc 24 from rotational movement. Thus, the brake disc is securely positioned in place. In the preferred embo diment of the present invention, the mounting projections 26 and 28 provide integral loading on the brake disc 24. By separately forming the fan and shroud from the hub, the fan and shroud may be of any appropriate material rather than the specific light alloy of the hub.

With the side panels 40, a cavity or shielded area is defined within which the discs rotate. The vanes 60 and shrouds 62 complete the closure with apertures for the flow of air in a radial direction. Air is received inwardly of the discs 24 through cooling air introduc tion ports 64. As can best be seen in Figure 1, ports 64 face directly forward. As can best be seen in Figure 2, the ports also extend outwardly of the leading profile of the disc system by means of angled panels 66 extending into the wind stream around the hub. The embodiment disclosed in Figures 1 and 2 thus enhances cooling of the discs 24 by means of the air ram effect of the angled panels 66, the radial pumping effect of the vanes 60, and the centrifugal cooling both through the internal passages 54 of the disc and about the disc resulting from rotation thereof.

The side panels 40 are intended as a mechanism for protecting the braking system from dirt, water and the like. Further to this end, screening material is employed in strategic locations. Screening members 68 are fixed by means of fasteners 70 to the panels 40 across the ports 64. The mesh size and construction of the screening members 68 are best determined by the material to be excluded. In the embodiment of Figures 1 and 2, conventional screening material is illustrated. The screening members 68 prevent the introduction of material in the air which might otherwise be introduced into the braking cavity defined by the side panels 40 through the ports 64.

About the inner side of the fans formed by blades 60 and adjacent the root of each vane 60 are screening members 72. Screening members 72 form a protective particle barrierforthe apertures between the vanes 60. The screening members 72 may be held in place by fasteners (not shown). The centrifugal force asserted on the screening members 72 when the wheel is in motion also tends to maintain the screening members 72 in position.

Looking to the embodiments of Figures 3,4 and 5, a cover 74 is fixed by means of fasteners 76 to each of the side panels 40. The cover extends generally inwardly to a position adjacent the hub 14 but spaced therefrom because of the relative motion between the hub and the cover 74.

The cover 74 is specifically designed to effect a closure of the volume surrounding the discs 24.

However, airflow past the discs 24 is also accommodated by apertures 78. The apertures 78 are disposed in an annular arrangement around the periphery of the discs 24. To further avoid contaminants within the brake disc cavity, the apertures 78 include screens 80 which may be individually arranged over each aperture 78 or may simply extend continuously along the inner surface of the covers 74. With the ram effect provided by the ports 64 and the rotational motion of the discs 24, airflow will be induced to flow outwardly through the apertures 78 without the addition of any rotating vanes such as in the embodiment of Figures 1 and 2.

Turning lastly to the embodiment of Figures 6,7 and 8, a hub and braking mechanism is illustrated which conforms substantially to the embodiments of Figures 1 and 2 with the exception that the screening mechanism, provided by screening members 68 and 72 in the aforementioned embodiment, are replaced by perforated plates 82 and 84. The perforated plate 82 is fixed by means of fasteners 70 to the side panel 40 as can best be seen in the simplified drawing of Figure 8. The perforated plates 82 are designed to effectively screen larger material which might enter through the ports 64 than the screens of the earlier embodiment. This is equally true of the perforated plates 84 which are arranged against the roots of vanes 60 in the same manner as the screen of Figures 1 and 2.

Thus, through the embodiments of the present invention disclosed above, both weight and size reduction can be achieved with shielded disc brake systems without compromising cooling requirements.

Claims

1. A disc brake apparatus for a motorcycle having a wheel hub, comprising a brake disc fixed to rotate with said hub, a caliper member fixed to the motorcycle for braking engagement with said brake disc, a side panel covering said brake disc on the other side of said disc from the hub and including at least one cooling air introduction port, means radially adjacent the periphery of said brake disc for inducing radially outward flow of said cooling air, and screening means across said cooling air introduction port and/or said airflow inducing means.

2. Apparatus as claimed in claim 1, wherein the or each said cooling air introduction port is located inwardly of the braking surfaces of said brake disc and opens forwardly relative to the motorcycle for air ram effect when moving.

3. Apparatus as claimed in claim 1 or 2, wherein the or each said screening means is a mesh screen.

4. Apparatus as claimed in claim 1 or 2, wherein the or each said screening means is a perforated plate.

5. Apparatus as claimed in any of the preceding claims, wherein said air flow inducing means includes a fan located radially adjacent the periphery of said brake disc and fixed to rotate with said hub.

6. Apparatus as claiamed in any of the preceding claims, wherein said side panel defines an annular opening between it and the hub radially adjacent the periphery of said brake disc, and including a cover fixed to said side panel and extending across said annular opening, said cover including annularly disposed apertures therethrough.

7. A disc brake apparatus for a motorcycle having a wheel hub, comprising 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, a side panel covering said brake disc on the other side of said brake disc from said hub and defining an annular opening between said side panel and the hub radially adjacent to the periphery of said brake disc, and a cover fixed to said side panel and extending across said annular opening, said cover including annularly disposed aper tues therethrough.

8. Apparatus as claimed in claim 7, further comprising screening means positioned across said apertures.