Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates generally to braking systems
and more particularly to a ~luid pressure actuated brake
anti-lock control apparatus and method of bra~ing a rotating
member.
Prior recognition of the phenomenon known as "locking" '~
in the braking or slowing of a rotating member such as an
automotive vehicle wheel has led to the development of anti-
lock control devices or brake modulators. Typical approaches ;
to overcoming the problems of locking may be found in prior
United States Patents No. Re 28,562 and 3,833,097. A related
approach may be found in co-pending application Serial No.
246,015 filed February 18, 1976 and entitled "ANTI-LOCKING F :
BRAKE APPARATUS AND METHOD". Interested readers are referred ~ ~
to the description and illustration there o~ "one conduit ~ ;
systems" for brake anti-lock controls or modulators. To
any extent necessary to understand this invention, the
description there given are hereby incorporated by reference
hereinto.
Persons skilled in the applicable arts relating to
automotive vehicles and braking systems therefor are familiar
with various power sources available on an automotive vehicle
and possibly useful in connection ~ith control functions such
as brake modulation. In part because of the availability of
electrical power and in part due to development of other known
electro-mechanical technology, the various anti-lock con-
trollers or brake modulators specifically referred to herein-
above have relied primarily upon electrically operated motive
means in achieving the desired anti-lock control. While such
reiiance upon electrical technology has achieved significant
success, it is recognized that the demands placed upon the -- -
electrical circuitry of an automotive vehicle may under
certain adverse circumstances be quite great.
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In light of the related development dlscussed above,
it is an object of the present invention to achieve anti-lock
control over fluid pressure actuated brakes by reliance upon
a circulating flow of pressurized fluid to power or provide j
motive force for an anti-lock control or modulator. In
realizing this object of the present invention, sole reliance
upon the electrical system of an automotive vehicle is avoided
and the possibility is opened of dealinq with substantially
higher levels of force.
~ccordingly, there is provided in accordance with
the present invention, in a wheeled automotive vehicle having
motive means for driving the vehicle, a hydraulic fluid circuit
including pump means driven by said motive means for circulat-
ing pressurized fluid therethrough, fluid pressure actuated
brake means for slowing a vehicle wheel, sensor means for
signalling the occurrence of an excessive rate of retardation
of the braked wheel, a conduit operatively communicating with
said brake means for applying thereto fluid under pressure,
and anti-lock means interposed in said conduit and responsive
to said sensor means for controllably interrupting and releasing
the application of fluid pressure to said brake means, the
improvement in said anti-lock means which comprises actuating
means operatively communicating with said hydraulic fluid
circuit for normal flow of circulating pressurized fluid there-
through and for blocking flow of pressurized fluid upon a
signalled occurrence of an excessive rate of retardation of the
braked wheel whereby motivating force for said anti-lock means
is transmitted from said motive means through said hydraulic
fluid circuit.
There is also provided in accordance with the present
invention, in a method of braking a rotating member which
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includes applying pressurized brake fluid to a brake for a
rotating member, signalling the occurrence of an excessive
rate of retardation of the braked rotating member, and con-
trollably interrupting and releasing the applled pressurized
brake fluid in response to signalled occurrences of an
excessive rate of retardation, the improvement comprising
pumping a flow of hydraulic fluid, and controlling the inter~
rupting and releasing of brake fluid by controlling the pumped
flow of hydraulic fluid in response to signalled occurrences.
The invention is illu-qtrated by way of example with
reference to the accompanying drawings, in which: -
Figure 1 is a partially perspective, partially ;
schematic, partially sectional view of an anti-locking device
or modulator according to the present invention, incorporated ;-
into a vehicle and shown in a normal or non-actuated condition;
Figure 2 is a view similar to a portion of Figure 1
and illustrating the device of Figure 1 in its actuated con-
dition; and ;
Figure 3 is a view similar to Figure 2 and illu~trating
an embodiment in which two devices are coupled together. ;
While the present invention will be described more
fully hereinafter with reference to the accompanying drawings,
it is to be understood at the outset of the detailed description
of this invention that it is contemplated that various modifi-
cations of the invention as described may be made by persons
skilled in the appropriate arts. For that reason, the detailed
description is to be read broadly, and not as limiting on the ;
scope of this invention.
Referring now more particularly to Figure 1, the
present invention is contemplated as having particular utility B~
in conjunction with a wheeled automotive vehicle having motive
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means as generally indicated at 10 for driving the vehicle. As
will be appreciated, the motive means 10 commonly is a petroleum
fueled internal combustion engine. The vehicle additionally
includes a hydraulic fluid circuit having a pump 11 which may
be driven by the motive means 10 for circulating a pressurized
fluid withdrawn from a reservoir 12. Persons familiar with the
design and operation of conventional automotive vehicles will
be aware that ~;uch pumps are commonly employed in conjunction
with power assisted systems on an automotive vehicle such as
10 certain forms of power steering and power brakes and may be
driven by means other than the vehicle engine. The vehicle
additionally includes fluid pressure actuated brake means for
slowing the rotating vehicle wheel membe~s and as generally !'
indicated at 14. Pressurized brake fluid is conventionally ~ ;
supplied to such a brake 14 through a conduit 15 which operative-
ly communicates with a master cylinder 16 or the like.
It has heretofore been proposed that an anti-lock control
or brake modulator may be interposed in a supply conduit such
as the conduit 15, for controllably blocking and relieving brake
20 pressure supplied therethrough. Such an anti-lock means, as
will be described hereinafter, is conventionally controlled by .
a retardation sensor such as a sensor means 17 for signalling
the occurrence of an excessive rate of retardation of a braked !,'~
rotating vehicle wheel member. Various forms of such sensors
are known to persons skilled in the applicable arts and are ~-
described in the aforementioned related patents and in co-pending ~'
Blomberg Canadian application S.N. 246,018, to which the
interested reader is referred. The sensor 17 in the arrange- $
ment according to the present invention may take any such known
30 form but is preferred to take a form which electrically signals
such an occurrence by means of conductors 18. Certain such
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sensors will be understood as signalling occurrences of wheel
slip and are, for purposes of this description, deemed compar- :
able to sensors signalling excessive rates of retardation. :
An anti-lock means in accordance with the present invention
is generally indicated at 19 and, in common with the anti-lock
devices or brake modulators described in the afore-mentioned
related patents, functions in response to the sensor means 17
for controllably interrupting and releasing the application
of fluid pressure through the conduit 15 to the brake 14.
In accordance with the present invention, the anti-lock means
19 includes a housing 20 including a brake fluid passageway
21 in which is positioned a valve member 22 which is biased
toward a seat 24 by a suitable spring 25. The valve member
22 is normally held in an unseated position by a pin 26 which
extends from a fluid pressure piston means 28 which is thereby
operatively coupled for actuating the valve member 22 to con-
trollably interrupt the application of fluid pressure. As will .
be appreciated from Figure 1, pressurized brake fluid normally
flows freely in both directions through the conduit 15 and
20 past the valve member 22 inasmuch as the member 22 is normally .
held in an unseated position by the piston means 28 and pin
26.
In accordance with the present invention, the hydraulic
fluid circuit including the pump 11 and the reservoir 12 has at
least a branch by means of which a circulating flow of fluid
is passed through a cylinder means 29 which encloses at least
a portion of the piston means 28. Interposed in the fluid
circuit between the cylinder means 29 and the reservoir 12 and
in the return flow path for fluid is a control valve member 30
30 which is biased toward a seat 31 by a spring 32. The control .
valve member 30 is noxmally maintained in an unseated position
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by engage~ent th~rewith of a control pin 34 extending from an
armature 35. The armature is biased toward the flow permitting
p~sition by a spring 36.
As will be noted, a winding 38 which is electro-magnetically
coupled with the armature 35 is electrically connected with
the sensor conductors 18, 80 as to be energized in the event
that an excessive rate of retardation of the braked rotating ~ -
vehicle wheel member occurs. Upon energization of the winding
38, the armature 35 is shifted to permit seating of the control
valve member 30, thereby blocking flow of pressurized fluid
from the cylinder means 29. Upon the flow of fluid from the
cylinder means 29 being blocked, the piston means 28 is moved
against the force of a return spring 39 in such a direction
as to permit seating of the anti-lock valve member 22 and
enlargement of the volume communicating with the conduit 15 and
brake 14 (see Figure 2). As a result, motivating force for the
anti-lock means is supplied by the fluid circulating means
including the pump 11 and reservoir 12.
Figure 3 illu~trate~ an embodiment using two anti-locking
means according to the invention coupled in series one with
the other by a connecting conduit 50. Elements of the arrange-
ment of Figure 3 corresponding to elements shown in Figures
1 and 2 have been identified by similar reference characters
of a one hundred ~eries for one anti-lock means (to the left
in Fiqure 3) and of a two hundred series for the other. Such
an embodiment is useful, for example, in connection with 80-
called two circuit systems wherein a sensor may control both
the circuits by the common solenoid valve. Such an embodiment
can also be used in an anti-locking system utilizing a common
sensor for two wheels, such as a so-called axle-by-axle system.
Persons skilled in the applicable arts of designing
brake control systems for automotive vehicles will appreciate
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1060511
a variety of approaches which may be used to apply the present
inventionO In perhaps the simplest form, as is illustrated in
Figure 1, a single brake master cylinder and a single modulator
may respond to a single sensor means operatively connected
with one or more vehicle wheels. Somewhat more sophisticated -
systems may employ plural modulators under the control of one
or more sensors. By such arrangements, sensors may be provided
for individual non-driven wheels and for paired driven wheels.
Further, sensors may be provided for individual driven wheels,
with the sensors being paired for control of a modulator for
the corresponding wheels. Other and further permutations of
such arrangements will be brought to mind by these brief
comments, such as arrangements in which all wheels are provided
with wheel retardation sensors, the front and rear axles each
having a modulator device. Yet another arrangement might
provide an indivldual retardation sensor and modulator device
for each of the rear wheels while the front wheels have a common
wheel retardation sensor and modulator, using an arrangement
such as that of Figure 3. Finally, each wheel may have its
own wheel retardation sensor and its own modulator.
In the drawings and specification, there has been set
forth a preferred embodiment of the invention, and although
specific terms are employed, they are used in a generic and -
descriptive sense only and not for purposes of limitation.
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