Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITL~ OF THE INVENTION
Brake disks
BACKGROUND OF THE INVENTION
Fiela of the invention
The present invention generally concerns brake disks and
more particularly, such disks having an annular core and
friction pads mounted on opposing radial faces of the core.
The invention also concerns a method of producing a brake
disk of this type.
Description of the prior art
It is known to provide brake disks wherein friction pads are
fastened on opposing faces of a disk core by various
mechanical means such as snap fasteners, rivets, force-fit
fasteners or by welding.
A prior art search made by the Applicant has revealed, in
this respect, U.S. patent no. 4,276,969 to CHIN et al. who
; propose providing a brake disk comprising a disk-like core
and friction pads disposed two-by-two on opposing surfaces
of the core. The pads are fixed to the core by means of
cylindrical bushings extending across the core and
projection welded to the pads to hold the assembly fast with
the core.
The search has also disclosed U.S. patent no. 4,613,021 to
LACOMBE et al., wherein the core is a spoked hub and the
friction pads are sector-shaped members mounted between the
spokes of the hub and held in position by hook joints at an
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outer end and spring-like hub rings at an inner end pressing
the hook joint components in the hook joints.
A further document found, U.S. patent no. 3,759,354 to
DOWELL et al., discloses a brake disk of the same general
type, in which the pads are sector-shaped and held together
in succession by mechanical joints.
In constructions of the type described above and under the
extreme temperatures to which the friction pads are
subjected during braking, it has been found that they are
prone to loosen on the core.
The structures disclosed in the above patents also have in
common that they are of complex design and therefore
difficult to assemble and costly to produce.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a brake
disk in which the friction pads are held safely on the core
against loosening in an extremely simplified manner, thereby
resulting in a low-cost article of manufacture.
According to the invention, the friction pads are embedded
in the core during casting of the latter except of course
for the friction surfaces of the pads which are preferably
flush with the core.
, 30 Thus, the invention provides a brake disk comprising an
annular core made of cast metal and a plurality of friction
pads set in the core on its opposing radial faces, the pads
having coplanar radial friction surfaces, wherein the cast
metal circumscribes the friction pads and fills, at least
partially, holes made through the pads to secure them firmly
to the core. In a preferred form, the core cast metal falls
flush with the friction surfaces of the pads.
Another object of the invention lies in providing a method
of producing a brake disk of the above type. This method
essentially comprises providing a mold including a pair of
mold shells, each shell having a bottom wall with a flat
peripheral portion, and a plurality of pairs of holding
plugs disposed at regular intervals along this peripheral
portion, the plugs jutting out from the bottom wall;
providing pad-retaining means in the bottom walls of the
shells for each of the friction pads; hanging flat friction
pads, each formed with a pair of through holes, from the
holding plugs over the pad-retaining means so that they be
pressed against the flat peripheral portion by said
retaining means; placing disk molding core means in the
shell between the bottom walls; closing the mold and pouring
casting metal into the mold around the core means, around
the friction pads and into the through holes to produce the
brake disk.
A non-limitative description now follows of a preferred
; embodiment of the invention, made with reference to the
appended drawings.
BRIEF DESCRIPTION OF THE DRA~INGS
Figure 1 is a perspective view of a disk brake construction
using a brake disk made according to the invention;
'.
Figure 2 is a cross-section, along line II-II in Figure 3,
of a portion of the brake disk taken in the brake lining
area;
Figure 3 is a front view of part of the brake disk,
partially broken away to show its inner structure;
Figure 4 is a cross-section along line IV-IV in Figure 3;
Figure 5 is a front view of a portion of one of the mold
shells used in molding a brake disk made according to the
invention; and
Figures 6 and 7 are cross-sections along lines VI-VI and
VII-VII of Figure 5, respectively.
DESCRIPTION OF THE PREFE~RED EMBODIMENT
The illustrated brake disk 1 is for use on a conventional
brake construction 3 having a hub 5 on which the disk l is
mounted and an outer caliper housing 7 containing brake
linings 9 -(Figure 2).
The brake disk or rotor 1 comprises an annular core 11, cast
in light metal, such as aluminum, over the opposing faces
13, 13' (Figure 2), of which are set a plurality of friction
pads 15 having coplanar radial friction surfaces 17 that are
of course clear of core cast metal. As shown, the cast metal
circumscribes the friction pads 15 and preferably falls
flush with the pads friction surfaces 17 to hold the pads
firmly in the core 11.
The friction pads 15 consist of small plates that are
preferably sector-shaped and have radially oriented side
edges 19, l9' (Figure 3), outer arcuate edges 21 and inner
arcuate edges 23. They are formed with peripherally outward
holes 25, partially filled with cast metal as further
explained hereinafter, and inward holes 27, completely
filled with cast metal, again to hold the pads 15 firmly in
the core.
All holes 25, 27, have the same configuration so that only
one will be described with reference to Figure 4,
particularly.
As shown, each hole defines a tapering bore 29 that
converges from the pad friction surface 17. Within the core
11 itself, the bore 29 is defined by an annular bead 31 that
projects inwardly from the inner surface 33 of the pad 15.
It will be noted that the bead 31 also forms an annular
retaining shoulder 35 preferably perpendicular to the inner
A 15 surface 33 and located radially outwardly of the bore 29.
To provide still a better embedding of the pads 15, the
latter have their peripheral edges 19, 19', 21, 23, taper
radially outwardly from the friction surfaces 17.
Preferably, the peripheral edges 19, 19', 21, 23, taper at
an angle of about 15, while the bores 29 taper at an angle
of about 20, both to the vertical.
It will be noted form Figure 2 that the outward holes 25 are
only partially filled with cast metal 11 while the inward
holes 27 are, as shown in Figure 2, completely filled, as
said above.
The cast metalll is preferably a heat conductive, light
metal alloy such as an aluminum alloy, that may be
reinforced with suitable fillers if necessary. It may also
be a nickel-based refractory alloy or molybdenum or
beryllium. As to the friction pads 15, they may
-- 5
advantageously be made of gritted material such as carbon-
silicon-carbide material, or gritted metal that is heat
conductive and very resistant to abrasion. Indeed, the
purpose of these pads is to "reinforce" the core of light
metal alloy where this core is subject to intensive
friction.
To improve heat dissipation, the annular cast metal core 11
is preferably formed with appropriate ventilating louvers 37
between the opposing faces 13, 13', of the rotor disk 1. It
is also formed, on one side, with radial brackets 39 (Figure
3) for connection to the hub 5.
As said above, the invention also concerns a method of
- 15 producing a brake disk of the type described above.
Reference is made, in this respect, to Figures 5, 6 and 7,
showing a portion of one of the two shells 41 of a mold
suitable for making the disk; the inner molding core having
been omitted. The shell 41 is cup-shaped and has a circular
bottom wall with a peripheral flat portion 43 from which
project a plurality of pairs of short plate-holding plugs 45
(Figures 5 and 6) equally distributed around its periphery;
each pair corresponding to one friction pad 15. Also,
corresponding to each pad 15 are holes 47 (Figure 7) through
the mold 41; these holes being operatively connected to an
air suction source 49 which acts as pad-retaining means as
will be explained hereinafter. Instead of such air suction,
it could be made of small magnets embedded into the mold
surface to retain the friction pads.
In use, the plate-shaped friction pads are hooked by their
outward holes 25 on the said plugs 45, provided on the flat
peripheral portion of the mold bottom wall 43, and the holes
47 connected to the suction source 49 to draw their friction
surfaces 17 tight against the shell bottom walls 43 and thus
retain them. An appropriate disk molding core is then
inserted in the shells 41 which are brought together to
close the mold. The casting metal is poured into the mold
around the molding core, around the periphery of the pads 15
and into the through holes 25, 27. Because of the particular
design of the pads 15 (bevelled edges 19, 19', 21, 23;
tapered holes 25, 27, and annular beads 31), it will be
appreciated that the pads 15 are solidly embedded in the
cast metal core 11. It will be seen also that the mold and
pad construction are extremely simplified while the mold
preparation is limited to a small number of operations.
The brake disk disclosed hereinabove has numerous
advantages. First of all, it is very light as compared to
the existing one-piece brake disk, since its core is made of
light material such as aluminum or magnesium which have been
rejected so far because of their lack of resistance. It is
also very efficient to dissipate heat, thereby making its
braking efficiency steady. Furthermore, it can be used very
efficiently as part of an ABS brake control system. In such
system, it is necessary to measure the rotational speed of
each wheel to adjust and balance the braking force applied
to each wheel. With the brake disk according to the
invention, this measurement can be made in a very easy,
simple and reliable manner, by fixing a Hall-effect sensor
10 onto the caliper 7 so that it extends at a few
millimeters from one side of the disk. The sensor 10 may
i count the number of pads 15 that pass in front of it because
they are made of a material different from the core, and
thus allows calculation of the speed of the disk.
