Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ 21 9~206-
"DISC BRAKE ASSEMBLY"
The present invention relates to disc brakes
and more particularly to improvements in large area
contact disc brakes for vehicles.
The disc brake of the present invention is a
disc brake of the type described in Canadian Patent
Applications No. 2,046,370 filed July 6, 1991 and
No. 2,110,996 filed June 22, 1992. These patent appli-
cations refer to full annular disc brakes for larger
lo vehicles such as trucks. The concept of the full annu-
lar disc brake is now proposed for automobiles and
light trucks and the present invention relates to a
structure of a full annular disc brake for such
vehicles.
A construction in accordance with the present
invention comprises a disc brake assembly for a vehicle
wheel wherein the wheel includes a hub journaled to an
axle on the vehicle, the disc brake assembly comprises
a housing mounted to the vehicle and at least an annu-
lar disc within the housing and means mounting the discto the wheel. The disc has at least a first radial
planar friction surface and the housing includes a
first brake shoe provided adjacent the first planar
friction surface of the disc and movable axially
towards and away from the first friction surface of the
disc for friction engagement therewith and release
thereof. Means are provided for restraining the first
brake shoe from rotating with the disc. The housing
also includes an annular radial wall parallel to the
first brake shoe, and an annular fluid expandable blad-
der extends between the first brake shoe and the radial
wall, whereby upon expansion of the bladder the first
brake shoe moves axially to frictionally engage the
friction surface of the disc and upon release of the
fluid from the expandable bladder, the first brake shoe
2 21 ~206
is to be disengaged from frictional contact with the
first frictional surface of the disc.
The features of the present invention can be
utilized for large trucks as well.
Having thus generally described the nature
of the invention, reference will now be made to the
accompanying drawings, showing by way of illustration,
preferred embodiments thereof, and in which:
Fig. 1 is an exploded fragmentary perspective
view of an embodiment of the disc brake in accordance
with the present invention;
Fig. 2 is a fragmentary radial cross-section
taken through the assembled disc brake;
Fig. 3 is a radial cross-section similar to
Fig. 2 but including further elements; and
Figs. 4a and 4b are enlarged fragmentary
cross-section taken along the same section as Fig. 3
but showing the elements in a different operative
position.
nReferring now to the drawings, a disc brake
assembly 10 for an automobile is illustrated having a
housing in the form of a shell 12. The housing has a
cylindrical wall 14 with a corrugated inner surface 16
having valleys 16a and ribs 16b. The housing 12
includes a radial annular wall 18 provided with an
annular brake pad lining 20. The ribs 16b are rela-
tively flat and represent valleys on the outer sur-
face 17.
The cylindrical wall 14 also includes a
radial flange 15. A spider 22 includes an annular
cylindrical corrugated wall portion 24 which is adapted
to fit within the corrugated surface 16 of the wall 14
and is retained by flange 15. That is the ribs 24a of
the corrugated surface 24 which will fit in the val-
leys 16a of surface 16 while the valleys 24b will cor-
respond to the ribs 16b of the housing wall 14. Thus,
the housing 12 will be locked against circumferential
- 3 - 21 9q 206
~, .,;
movements relative to the spider 22. The spider 22
a hub portion 26 which can be bolted to a flange oni~n
axle (not shown) of the vehicle. The spider 22 also has
a radial planar wall portion 28 and a cylindrical
flange 30.
An indented detent 70 is provided in the
housing wall 14 in order to lock the housing 12 against
axial movement relative to the spider 22. The detent 70
protrudes inwardly to engage the spider 22.
The wall 28 is adapted to receive strain
sensor 60. These strain sensor may be the type known
under Trademark MULTIDYN and described in U.S. Patent
No. 5,522,270 issued June 4, 1996 to THOMSON-CSF. The
strain sensor 60 can provide valuable information on
the braking efficiencies and the wear of the brake
shoes.
The strain sensor 60 extends somewhat tangen-
tially to the wall 28 and can, therefore, monitor the
torque being applied between the hub 26 and the cylin-
drical flange 30 of spider 22. With the information
which can be obtained from strain sensor 60, the tem-
perature of the brakes can be monitored by means of
suitable micro processors. For instance, when the
brakes are applied, the pressure is known, and if the
heat should increase the torque will be reduced.
Increased temperature of the brakes will normally
signal brake deterioration or malfunction.
Other criteria can also be determined logi-
cally from the known pressure, and the torque informa-
tion provided by the strain sensor 60.
An annular disc rotor 32 includes radial
planar friction surfaces 34 and 36 and a cylindrical
annular hub 38 having an inner corrugated surface 40
with ribs 40a and valleys 40b. A hub member 42 includes
a radial wall portion 44 adapted to be mounted to a
vehicle wheel and a cylindrical corrugated wall 46. The
wall 46 has ribs 46a and valleys 46b which are adapted
2 1 94206
to fit within the cylindrical wall inner surface 40 of
the disc rotor 32. Thus, the rotor 32 will be locked
against relative rotational movements with the hub 42.
Since the hub 42 is mounted onto a vehicle wheel the
rotor 32 will rotate with the wheel. The disc rotor 32
is ventilated and therefore has radially extending
ventilation passages 48 communicating with openings 49
in housing wall 14.
A brake shoe 50 includes brake linings 52 and
a backing plate 54. The brake shoe 50 includes a corru-
gated peripheral edge 51 engaging the inner surface 16
of the cylindrical wall 14. Thus, the brake shoe 50 can
slide axially but is retained against rotational move-
ment. An annular bellows 56 is provided between the
wall 28 and the backing plate 54. As described in Cana-
dian Patent Application 2,110,996, when fluid such as
air is fed into the bellows 56 it will expand, moving
the brake shoe 50 axially towards the friction surface
36 of disc rotor 32. The disc rotor 32 can also move
radially on the hub 42 and the radial surface 34 will
come in frictional contact with the brake linings 20.
Thus, when it is necessary to apply the brakes, the
bellows 56 is expanded. However, to release the brakes
the air is allowed to exhaust from the bellows 56,
thereby releasing the axial pressure on the brake shoe
50, allowing the disc rotor 32 to rotate freely within
the housing 12.
Referring now to Figs. 3, 4a and 4b, the
rolling seals will be described. The rolling seals 62,
which are located, in the present invention, on the
outer surface 46 of the hub 42, are formed to the
contour of the corrugated surface. As shown in Fig. 3,
the pair of rolling seals 62 are precompressed when
inserted between the hub 42 and the disc rotor 32.
Retainer ring 63 may be provided to hold seal 62a in
place. Seal 62b is retained by lip 65 formed in hub 46.
Retainer ring 63 is formed with convexly curved
2 1 94206
surface 63b to support seal 63a and control th~e
deformation of the seal as will be described. The
hub 46 is also formed with convexly curved surface 65b
to control seal 62b. When the disc rotor 32 slides on
the hub 42, as previously described, the rolling
seals 62 will deform in the direction of the path of
the rotor 32, as seen in Fig. 4b, ~hen it is pushed by
the brake shoe 50. When the brake is released, the
rolling seals 62 will return to their idle position, as
shown in Fig. 4a, thereby drawing the rotor 32 away
from the brake pad 20.
In the same manner, rolling seals 64 and 66,
which are located on the flange 30 and housing wall 14
respectively, engage the brake shoe 50, and will act to
return the brake shoe 50 away from the friction surface
34 of the disc rotor 32 to eliminate drag of the
brakes.
It is noted that the rolling seals 62 could
be located on the disc rotor and engaging the hub
rather than as set up in the present embodiment.
