CA1174988A

CA1174988A - Disc brake for motorcycles

Info

Publication number: CA1174988A
Application number: CA000394778A
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: 1984-09-25
Also published as: DE3202230A1; FR2498710B1; FR2498710A1; GB2093949B; GB2093949A

Abstract

ABSTRACT OF THE DISCLOSURE

A disc brake assembly for the front or rear wheel of a motorcycle including a brake disc having pairs of projec-tions located on its periphery at 120° intervals. The pairs of projections may be placed on either the outer periphery or the inner periphery of the brake disc. The projections define open ended recesses receiving bosses formed integrally with the wheel hub, and partially surrounded by hardened retainers. A bolt threaded into each boss prevents disassem-bly of the bosses and recesses but is not subjected to forces caused by thermal expansion of the brake disc during braking.
One or more hydraulically activated stationary calipers clamp non-rotary brake pads frictionally against opposite faces of each brake disc. Provisions are made for cooling the brake disc by atmospheric air.

15.

Description

~ 17~988 S P E C I F I C A T I O N
DISC BRA~E FOR MOTORCYCLES
This invention relates to disc brakes for motorcyles.
According to one aspect of the invention, there is provided in a disc brake device for a motorcycle having a wheel hub, the combination of: a brake disc having pairs of projections located on a periphery thereof at equidistant locations forming equally spaced recesses, a plurality of bosses formed integrally with the wheel hub and each project-ing into one of said recesses, respecti~ely, stationary brake pads positioned o~ opposite faces of said brake disc~ caliper means for engaging said brake pads with said brake disc, the engagement between said bosses and said recesses permitting radial thermal expansion of said brake disc.
According to another aspect of the invention, there is provided in a disc brake device for a motorcycle having a wheel hub, the combination of: a brake disc having pairs of projections located on a periphery thereof at equidistant locations forming equally spaced recesses, a plurality of bosses formed integrally with the wheel hub and each projecting into one of said recesses, respectively, said brake disc comprising parallel annular plates having integral air cooling vanes between them, a stationary side panel having an inlet port for atmospheric air, stationary brake pads positioned on opposite faces of said brake disc, caliper means for engaging said brake pads with said brake disc, the engagement between said bosses and said recesses permitting radial thermal expansion of said brake disc.
According to another aspect of the invention, there is in a disc brake device for a motorcycle having a wheel hub, the combination of: a brake disc having pairs of projections located on a periphery thereof at equidistant locations forming equally spaced recesses, a plurality of bosses formed integrally with the wheel hub and each projecting into one of said recesses, respectively, means including bolts threaded into said bosses for retaining the engagement of said bosses and said recesses, stationary brake pads positioned on opposite faces of said brake disc, caliper means for engaging said brake pads with said brake disc, the engagement between said bosses and said recesses permitting radial thermal expansion of said brake disc without stressing said bolts.

~` la In the drawings:

Figure 1 is a sectional detail showing construction of a prior art device.

Figure 2 is a side elevation partly in section and partly broken away showing a preferred embodiment of this invention.

Figure 3 is a transverse sectional vie~ taken sub-stantially on the lines 3-3 as shown on Figure 2.

Figure 4 is a side elevation of the brake disc shown in Figures 2 and 3. - _ Figure 5 is a sectional detail taken substantially on the lines 5-5 as shown on Figure 4.

Figure 6 is a view simllar to Flgure 4, partly broken away a~d showing a modification.

Figures 7, 8 and 9 show another embodiment of this invention.

Figure 7 is a side elevation partly in section and partly broken away.

Figure 8 is a sectional elevation taken substantially on the lines 8-8 as shown on Figure 7.

Figure 9 shows a modification, Figures 10-15 show a third embodiment of the invention.

Figure 10 is a side elevation partly in section and partly broken away.

Figure 11 is a sectional view taken substantially on the lines 11-11 as shown on Figure 10.

Figure 12 is a sectionaI detail.

Figure 13 is a sectional view showing individual parts of Figure 12 prior to assembly.

Figure 1-4 is a sectional detail showing a portion of Figure 12 on an enlarged scale.

Figure 15 is a plan view of the retainer shown in Figure 12.

, Figures 16-21 show a fourth embodiment of this invention.

Figure 16 is a side elevation partly in section and partly broken away.

Figure 17 is a sectional view taken substantially on lines 17-17 as shown on Figure 16.

Figure 18 is a side elevation party in section showing a brake disc of the type shown in Figures 16 and 17.

Figure 19 is a sectional view taken substantially on the lines 19-19 as shown on Figure 18.

Figure 20 is a sectional detail showing modification.

74ssa Figure 21 is a sectional detail showing another modifi-cation.

~ eferring to the drawings, the prior art device shown in Figure 1 includes a wheel hub a having a brake disc b secured thereto at its peripheral portion c. A plurality of installation holes d are provided in the peripheral portion c of the disc b and a series of bolts e extend through the installation holes d into aligned holes in the wheel hub a. In this construction tAere is no play or looseness between the installation holes d and the outer surface of the bolts e, so that when the disc b is heated by friction generated during braking, the resulting thermal expansion of the disc b in the radial direction generates forces tending to deform the hub a. Stresses caused by deformation resistance of the hub a are likely to~develop in the disc b in addition to thermal stresses as a result o~ non-uniform tempera-ture d i str ibut ion .

Since there is no play or looseness between the installation holes d and the peripheral surface of the bolts e, as described above, low accuracy in the machining of the parts results in mismatching of the installation holes d to the holes f in the hub a. This may prevent or hinder insertion of the bolt e, and because of this, high accuracy machining has necessarily been required.

This invention relates to improvements in a disc brake construction ~or a motorcycle in which assembly of the parts is facilitated and centering of the brake disc is achieved without - 117~988 restricting radial displacement of the disc mount, even if radial displace~ent should occur because of thermal expansion of the disc during braking. Development of internal stress in the brake disc is thereby minimized.

Referring to Figures 1-6, the front wheel axle 1 is secured to front forks 2 at both ends, and the front wheel hub 4 is rotatably supported on said axle 1 by means of axially spaced bearings 3. The rim 5 is fixed to and becomes a part o~ the wheel hub 4. Laterally projecting bosses 6 are formed integrally on the hub 4 and are positioned at intervals o~ 120J around ~he periphery of the hub 4. Paired projections 11 on the hub 4 project radially therefrom and define recesses 7 which open radially outward and which hold each boss 6 through a retainer 13.
, The three double projections 1~ of the brake disc 8 have open ended recesses 7 defined between~`parallel walls 12.
The walls 12 are parallel to the radial line extending from the axis P o~ the brake disc 8 (see Figure 4). The double projec-tions 11 removably engage the mounting bosses 6 and retainers 13 by relative axial movement of the brake disc 8. Axially extending bolts 14 secure the covers 15 to the bosses 6.

A stationary side panel 16 is provided with a cooling air introduction port 17 and a stationary caliper 18 is fixed with respect to the side panel 16. Stationary brake pads 19 engage opposite sides of the brake disc 8. Energizin~ of the caliper pistons 20 causes the pads 19 to be brought into pressure contact with both sides of the brake disc 8.

When the mounting bosses 6 are engaged with the recesses 7 and defined in the double projections ll, no forced engagement on forced fitting is necessary even if mutual pitch errors are relatively large between the three mounting bosses and the three recesses 7. Thus, considering Figure 4 of the drawings, assume that engagement is made at locations A and B and assume that the mounting boss at location C is an imaginary point. The clearance produced by the relation between the groove width m and the boss width p and the double retainer thickness n determines the quantity of shifting w in the direction X-X at location C.
Therefore, even when the relative location difference between the mounting boss 6 at location C and the torque transmitting surfaces 12 of the brake disc 8 exists in the X-X direction, the brake disc 8 can readily be engaged without forc~ng to the mounting bosses 6 so long as said w exists. In addition, the clearances are sufficient to permit such error of w as is required for machining.

Furthermore a discrepancy along the Y-Y direction between the mounting boss 6 and the bottom wall of the recess 7 is absorbed by a specified clearance, insofar as the clearance is provided between the boss 6 and the bottom of the recess 7, there-by constituting no hindrance to the assembling operation.
Accordingly, relatively eas~ machining enables the brake disc 8 to be centered for installation at high accuracy.

Even though the brake disc 8 expands in the radial direction due to heat of friction or contracts as a result of cool-ing, the torque transmitting surfaces of the mounting boss 6 and 6.

1 17498~

walls 12 of the recess 7, expansion or contraction is not limited by the mounting bosses 6, and generation of thermal stresses may be reduced to a minimum for improved strength.

The brake disc 8 is formed with a plurality of radial s ribs 10 which define cooling air passages 9 between them.

Cooling air introduced through port 17 in the side panel 16 is exhausted to atmosphere through the cooling air passages 9 by virtue of centrifugal force, so that heat of friction generated on the brake disc 8 during braking action is diss~pated by the air to achieve considerable cooling effect.

In the modification shown in Figure 6 a pair of bosses 21 facing each other are provided on the wheel hub, and a projection 23 is provided on the brake disc 8a. ~he bosses 21 and the projection 23 are engaged with each other ,~through retaine_ 13a.
An e~uivalent operational effect is achieved.

In the second embodiment of the invention shown in Figures 7, 8 and 9, the rear wheel axle 1_ is fixed to the rear torque assembly 2b. The rear wheel hub 4b is rotatably supported on the rear wheel axle 1_ through axially spaced bearings 3b. The wheel rim 5 may be formed integ'rally with the outer periphery of the wheel hub 4b. On one side of the rear wheel hub 4_, a final driven flange 24 is installed, and a driven sprocket 25 is remov-ably secured thereto by means of bolts 26.

On the opposite side of the rear wheel hub 4b from the `sprocket 25 there are provided three mounting bosses 6_ which are formed integrally with the hub 4b and are equally spaced 120 apart. The brake disc 8_ has three double projections llb which define the recesses 7b receiving the mounting bosses 6_.
The recesses 7b receive the bosses 6b through relative axial movement between the bFake disc 8b and the wheel hub 4b.

The brake disc 8_ and the mounting bosses 6b are so formed that clearance is provided at the bottom of each recess 7b. This construction permits thermal expansion ~f the brake disc 8b in the radial directions.

A cylindrical portion 27, interrupted the mounting bosses 6b is provided on the wheel hub 4_ so as to have a ~
specified clearance with respect to the periphery of the brake disc 8b. A side panel 16_ is formed so as to close the inner surface of the cylindrical portion 27 and the brake disc 8b.
This side panel 16b is adapted to be remoyably installed on the mo~nting bosses 6b of the rear wheel hub 4b by means of bolts 14b so that its peripheral portion 36b is placed opposite to the edge 37_ of the cylindrical portion 27 of the hub 4b. A caliper member 18b is fitted integrally to the.side panel 16b and straddles the brake disc 8_ from the inner side.
A pair of pads 19_ engage both sides of the brake disc 8_ in slidable contact, by operation of the caliper piston 20b.
The caliper member 18_ is fixed on the caliper bracket 28, so that reaction force which acts on the caliper member 18b is transmitted from the bracket 28 through a link 29 to the vehicle body.

1 17498~

Because the brake disc 8b is covered by the rear wheel hub 4b and side panel 16b, the brake disc 8b is prevented from contact by water, dust, etc., on its surface, and therefore wear of the brake disc 8_ and the pads 19_ is reduced. Also, the engagement of the peripheral double projection llb on the brake disc 8b with the mounting bosses 6b of the rear wheel hub 4b, braking force acting on the brake disc 8_ is reliably transmitted to the rear wheel hub 4b. In addition brake torque is borne on the mounting bosses 6b and does not act on the bolts 14b so that the bolts maintain a reliable connection with the mounting bosses 6b for a long period of time.

In the modification shown in Figure 9, the brake disc 8b is pr~vided with three equally spaced projections 23_. These are received between pairs of bosses 30 fixed to the wheel h~b 4b and clearances 31 are provided between;the inner periphery of the holding bosses 30 and the outer periphery of the brake disc 8b. ~his construction provides practically the same operational effect as the construction shown in Figures 7 and 8.

The third embodiment of this invention shown in Figures 10-15 employs a rear wheel axle lc fixed to the rear fork assembly 2c, and a rear wheel hub 4c supported on axially spaced bearings 3c.. The final driven flange 24c is connected by bolts 26c to the driven sprocket 25c. On the side of the hub 4c opposite from the position of the driven sprocket 25c are three mounting bosses 6c formed integrally with the hub 4c. The brake disc 8c has double projections 11_ which receive a .

hardened retainer 13c. The brake disc 8c is provided with radially extending ribs lOc which define cooling air passages 9c between them. Clearance is provided between the outer periphery of the brake disc 8c and the bottom of the retainers s 13c, in order to absorb thermal expansion of the brake disc 8c.

As best shown in Fig~res 12 an~ 13, each projecting boss 6c of the wheel hub 4c loosely receives the U-shaped peripheral portion of the retainer 13c, one side being designated 32 and the other side being designated 33. The side 33 is ~ent at an accute angle prior to assem~ly, as shown in Figure 13, whereas the side 32 is bent at a right angle. The part 34 is adjacent the brake torque transmitting end of the boss 6c and part 35 is on the opposite side thereof.
The side panel 16c does not rotate but-it has an opening 17c through which atmospheric air enters for cooling the brake disc 8c. The side panel is clamped in place by suitable means, not shown.

The cylindrical portion 27c is so formed as to have a s~ecified clearance with respect to the periphery of the brake disc 8c. The side panel 16c is formed so as to close the inner surface of the cylindrical portion 27c of the brake disc 8c. The stationary side panel 16c has a peripheral portion 36c spaced from the annular shoulder 37c on the wheel hub 4_, dèfining a clearance space 38c for discharge of heated air.

The stationary caliper member 18c carries stationary pads l9c which frictionally contact both faces of the brake disc 8c under force of the caliper piston 20c.

10 .

The surface of the-double projection llc is pressed against the wheel hub 4c by the resilient restoring moment of the retainer part 33, preventing the disc 8c from loosening due to vibration, etc. Even when an impact force is applied to the brake disc 8c, the inside surface of the double projec-tion llc and the sides of the mounting boss 6c limit the amount of wear because of the use of the hard retainer 13c.

The operational features of the embodiment of the invention shown in Figures 10-15 as to cooling, thermal expansion, etc. are similar to those described in connection with the embodiment of the invention shown in Figures 7, 8 and g. , Referring to the fourth embodiment of this invention shown in Figures 16-21, the parts are ~imilar to those shown in Figures 1-6 except that only one brake qisc 8d is employed instead of two and that somewhat different air cooling vanes are provided on the brake disc in the vicinity of the three integral bosses fixed,to the wheel hub. Thus the wheel hub 4d is supported on axially spaced bearings 3d on stationary axle , ld 'affixed to the forks 2d. The single brake disc 8d has three dual projections lld which receive the three bosses 6d which are formed integrally with the wheel hub 4d. Radial ribs lOd define cooling passages 9d between them and an addi-tional thîckened rib 39 straddles each integrally boss 6d and its associated retainer. Atmospheric air for cooling enters the port 17d in the stationary side panel 16d and is discharged through space 38d. The piston 20d of the caliper 11 .

18d clam~ps the rotary pads l9d aga1nst the outer faces of the brake disc 8_.

Figure 20 shows a modification in which the brake disc 8e is provided with internal double projections lle for receptions of the three bosses 6e formed integrally with the wheel hub. A thickened rib 40 straddles each of the integral bosses 6e, In the modification of Figure 21 the brake disc 8f is similar to the brake disc 8d shown in Figure 18 except that the dual projections llf carry thickened vanes 41 defining the recess 7f between them. ~ ~~~

Having fully described my invention, it is to be understood that I am not to be limited to the details herein eet forth, bu~ that my invention is of the full scope of the append~d claims.

Claims

I claim:

1. In a disc brake device for a motorcycle having a wheel hub, the combination of: a brake disc having pairs of projections located on a periphery thereof at equidistant locations forming equally spaced recesses, a plurality of bosses formed integrally with the wheel hub and each project-ing into one of said recesses, respectively, stationary brake pads positioned on opposite faces of said brake disc, caliper means for engaging said brake pads with said brake disc, the engagement between said bosses and said recesses permitting radial thermal expansion of said brake disc.

2. The combination set forth in claim 1 in which said pairs of projections and said recesses are located on the outer periphery of said brake disc.

3. The combination set forth in claim 1 in which said pairs of projections and said recesses are located on the inner periphery of said brake disc.

4. The combination set forth in claim 1 in which said bosses are each partially surrounded by a hardened retainer.

5. In a disc brake device for a motorcycle having a wheel hub, the combination of: a brake disc having pairs of projections located on a periphery thereof at equidistant locations forming equally spaced recesses, a plurality of 13.

bosses formed integrally with the wheel hub and each project-ing into one of said recesses, respectively, said brake disc comprising parallel annular plates having integral air cooling vanes between them, a stationary side panel having an inlet port for atmospheric air, stationary brake pads positioned on opposite faces of said brake disc, caliper means for engaging said brake pads with said brake disc, the engagement between said bosses and said recesses permitting radial thermal expansion of said brake disc.

6. In a disc brake device for a motorcycle having a wheel hub, the combination of: a brake disc having pairs of projections located on a periphery thereof at equidistant locations forming equally spaced recesses, a plurality of bosses formed integrally with the wheel hub and each project-ing into one of said recesses, respectively, means including bolts threaded into said bosses for retaining the engagement of said bosses and said recesses, stationary brake pads positioned on opposite faces of said brake disc, caliper means for engaging said brake pads with said brake disc, the engagement between said bosses and said recesses permitting radial thermal expansion of said brake disc without stressing said bolts.

14.