Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION
This invention relates to a motor vehicle braking
system providing automatic braking when the vehicle, moving
in reverse, detects an obstruction.
RACKGROUND OF THE INVENTION
It is already known, particularly in connection with
goods-carrying vehicles, to provide at the rear of the vehicle
(which may for example be a wagon or the trailer of a tractor/
trailer combination) a detector which, when the vehicle reverses,
detects an obstruction and serves to generate a signal which
can be used to initiate application of the vehicle's brakes
so bringing the vehicle to a standstill and minimising the risk
of damage or injury to any obstruction or person behind the
vehicle.
There are several types available, and at least one
such known system is interrelated to a driver-controlled reverse
selector on the vehicle in such a manner that the system is armed
or made ready for brake application to be effected upon receiving
a signal from the detector only when the vehiclels driver has
selected reverse gear. Thus, with this system a signal generated
by the detector causes brake application only when the vehicle's
driver has deliberately operated the selector for the vehicle
to be driven backwards.
There are other methods which necessitate the engaging
of an electrical switch, or the operating of a camera and associated
equipment, and rely on the driver to control or activate. ~one
of these will operate, therefore, if for instance the vehicle
should commence running backwards, e.g. down a hill when out of
gear, or as a result of being impacted at the front. Thus, the
prior proposed systems do not safeguard against the risk of
accident in the event of unintentional reverse movement of the
vehicle, which can arise in a substantial number of varied
circumstances of which possible the most important one is the
risk arising from inattentive parking upon an inclined surface.
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An object of the present invention is to provide a
braking system ~hich safeguards against any reverse movement,
whether intentional or unintentional, and in which the need for
the operation of switched, or a reverse selector of the vehicle
to have been shifted into the reverse condition, is obviated.
STATEMENT OF THE INVENTION
In its broadest aspect the invention consists of a
method of automatically actuating the braking system of a
vehicle, comprising-the step of sensing the rotational direction
of a member which rotates in one direction in the forward
direction o movement of the vehicle and in the opposite
direction in the reverse direction of movement of the vehicle and
arming the system, upon sensing rotation of the member in said
opposite direction and, while the system is thus armed and the
vehicle is moving in the reverse direction, detecting the vehicle
contacting an obstruction and thereby generating a signal to
cause brake application.
In another aspect the invention consists of a motor
vehicle braking system comprising: detector means, positioned
on the vehicle, constructed and arranged to detect the vehicle
contacting an obstruction when the vehicle is moving backwards
and to generate a signal on said contact; sensor means effective
to sense the rotational direction of a member which rotates in
one direction in the forward direction of movement of the vehicle
and in the opposite direction in the reverse direction of
movement of the vehicle, said sensor means serving, upon sensing
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rotation of the member in said opposite direction, to arm the
system; and means actuable by the detector signal to cause brake
application.
BRIEF DESCRIPTION OF THE DRAt~lNGS
An example embodiment of the invention is shown in the
accompanying drawings in which:
Figure 1 is a perspective view of the rear portion of
the trailer of a tractor-trailer combination;
Figure 2 is a transverse cross-sectional view of
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the rear bumper of the trailer taken along line 2-2 of Figure l;
Figure 3 is a cross-sectional view of a first
embodiment associated with the wheel hub assembly of the
trailer of Figure l;
Figure 4 is an explod~d perspective view of the
rotation detector of the wheel hub assembly of Figure 3;
Figure 5 is a view of the magnetic activator disc
of .he rotation detector of Figure 4 taken along line 5-5
of Figure 3 and showing its position in relation to the
valve pin when the trailer is moving forwardly;
Figure 6 is a cross-sectional view taken along
line 6-6 of Figure 5;
Figure 7 is a view similar to Figure 5 showing
the position of the disc in relation to the valve pin when
the trailer is moving in reverse;
Figure 8 is a cross-sectional view taken along
line 8-8 of Figure 7;
Figure 9 is a schematic flow diagram of the air
brake system of the device;
Figure 10 is a flow diagram similar to Figure 9
showing the brake system in operation;
Figure 11 is a cross-sectional view of a second
embodiment of the invention associated with the drive shaft
of a vehicle;
Figure 12 is a view taken along line 12-12 of
Figure 10; and
Figure 13 is a view taken along line 13-13 of
Figure 11.
DESCRIPTIONOF PREFERRED EMBODIMENT
The embodiment shown in the drawings consists
of a trailer 10 of a tractor-trailer combination, with a
body frame 12 and including a set of réar wheels 14 compris-
ing a pair of wheels 16 journally mounted for free rotation
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on a fixed axle 18. A fixed bumper frame 20 depends from
body frame 12 and carries a rearwardly projecting pneumatic
bumper tube 22 of flexible material. As seen in Figure 2?
a second pneumatic tube 24 is disposed within bumper tube 22
and extends substantially the length of the bumper tube.
The hub assembly of one wheel 16 is shown in
Figure 3 and comprises a wheel hub 26 journally mounted by
bearings 28 on a fixed axle 30 having an axle bore 32 closed
at one end by a plug 32 which is fixed by set screws 33 to
the axle and which faces a hub cap 34 mounted on boss 36 of
wheel hub 26. As seen more particularly in Figure 4, a first
magnet disc 38 is axially mounted for rotation on plug 32
by a pivot bolt 40 and spaced from the plug by a bushing 42
on the disc. The outer face 44 of disc 38 carries a ring 46
of fixed, spaced magnets. A stop pin 48 projects from plug
32 through a first aperture 50 in disc 38 and a spring air
valve 52 projects from the plug through a second aperture 54
in disc 38 radially opposite to aperture 50 with respect to
aperture 50. A second magnet disc 56 faces first magnet
disc 38, being fixed to hub cap 34 on blocks 58 by bolts 60.
Disc 56 carries a ring 62 of fixed, spaced magnets which
registeres with ring 46 on disc 38.
The air flow system associated with trailer 10,
as shown in Figure 9 of the drawings, consists of an air
brake supply line 70 passing to brake system 71 of the
trailer through a normally open port 72 of a first shuttle
valve 74 and an auxiliary air line 76 normally closed by
shuttle valve 74. Auxiliary air supply line 76 is connected
by a line 78 to a pressure reducing valve 80 and from valve
80 through a line 81 to normally closed spring air valve 52.
Line 81 is connected by a line 82 to control port 83 of a
first normally closed pass control valve 84. Auxiliary air
supply line 76 i9 connected through line 78 by a line 120 to
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pass control valve 84, thence by a line 86 to a second normally
open pass control valve 88, and thence by a line 90 to
connect with a line 92 impinging on one end g4 of a second
shuttle valve 96 which bears at its-other end on a compression
spring 98. Line 92 connects also through a normally closed
third pass cor.trol valve 100 and a line 102 to impinge on one
end 104 of first shuttle valve 74. Air supply line 78
connects, by a line 106 through a normally open port 108
of second shuttle valve 96, with a line 110 which impinges
on the other end 112 of first shuttle valve 74. Bumper tube
24 is connected by an air line 114 to control port 116 of pass
control valve 100 and to a normally open port 118 of shuttle
valve 96 to air. Brake supply line 70 is connected by a line
124 to control port 126 of pass control valve 88.
In the oper~tion of the embodiment of Figures 3
to 8 the operator normally controls the brake system of
trailer 10 through brake line 70. When trailer 10 is moving
forward magnetic disc 56 rotates magnetic disc 38 in the
direction of arrow 130 as seen in Figure 5 and pin 48
prevents valve 52 from being opened, as seen in Figure 6.
However, movement of trailer 10 in reverse, i.e. backwards,
causes disc 56 to rotate disc 38 in the opposite direction
as indicated by arrow 132 in Figure 7 and this movement of
disc 38 opens valve 52 as seen in Figure 8~
The opening of valve 52 vents air from
lines 81 and 82 which opens port 83 of valve 84 and allows
pressurized air from line 120 to pass through valve 84,
line 86, valve 88, line 90 and line 92 to throw shuttle valve
96, against the action of spring 98, in the direction of arrow
134 as seen in Figure 10, thus sealing the venting of line
114 and relieving the pressure on end 112 of shuttle valve 74.
Also the venting of bumper tube 24 is cut off. This brings
the brake system into readiness for automatic operation by
the contact of bumper tube 22 with an obstruction.
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When bumper tube 22 comes into contact with any
obstruction an air pulse is sent from tube 24 along line
114 to valve 100 which opens port 116 and allows pressurized
air from line 92 to pass through line 102 and against end
104 of shuttle valve 74, throwing valve 74 in the direction
of arrow 136 as seen in Figure 10, thus closing line 70
and opening line 76 through part 138 to brake system 71.
This automatically operates brake system 71 to stop the
reverse movement of trailer 10 immediately.
In order to release the brake system from the
automatically actuated mode the operator of the vehicle
presses the foot brake which actuates valve 88 through lines
70 and 124 to port 126. This closes valve 88, cutting off
the air supply to lines 90 and 92 and relieving the pressure
on end 94 of shuttle valve 96. Shuttle valve 96 is thus
allowed to be thrown back by spring 98 to its normal posi-
tion and allows air from line 10~ to pass through port 108
and line 110 to end 112 of shuttle valve 74 which throws
that valve back to its normal position.
When the operator releases the foot brake port
126 is closed which returns the system to its armed mode.
On the resumption of forward movement of trailer 10, air
valve 52 returns to its normal closed position as seen in
Figure 5 and 6. This closes port 83 of valve 84, thus
returning the system to its original (nDrmal) mode of
operation.
In the embodiment shown in Figures 11 to 13 of
the drawings the invention is activated through drive shaft
150 of a vehicle which carries a circumferential band 152
of magnets. An arcuate head 154 floats over band 152 and
comprises a curved plate 156 carrying a row 158 of magnets
on its concave side concentric with band 152. Head 154 is
carried by a pair of support arms 160 fixed to a block 162
on the chassis of the vehicle. The free end portion 164 of
each arm 160 carries lateral flanges 166 which are enclosed
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in a bearing box 168 encasing a row of spherical bearings
170 along each crevice formed by flanges 166 which free
end portion 164. Stops 172 limit the travel of plate 156.
Plate 156 is connected through a pivot pin 174 to one end
of a link arm 176 which is pivotally connecting through a
slot 178 at its other end to a pin 180 on block 162. Spring
valve 52 projects through an aperture 182 located in arm
176 between pivot pins 174 and 180.
In the operation of the embodiment of Figures 11
to 13 the rotation of drive shaft 150 in the forward opera-
tion of the vehicle causes plate 156 to move in the direction
of arrow 184 by the action of the magnets of band 152
on the magnets of row 158, keeping air valve 52 centred in
aperture 182. When the vehicle moves in reverse the rota-
tion of drive shaft 150 in the opposite direction causes
plate 156 to move in the same direction which causes link
arm 176 to move opening air valve 52 and arming the system
of Fipure 9 in the same manner as previously described.
