Note: Descriptions are shown in the official language in which they were submitted.
20~334
This system has three conditions in the wheel assembly that
are monitored: (Fig.2)
1. Push Rod Travel - This is monitored by a permanent
magnet mounted to the air brake push rod (Fig.3), a non
magnetic housing surrounds the magnet and contains a
magnetically activated reed switch that is encased in a
coil. This coil allows the operator to test the reed
switch before the system is put into its brake monitoring
mode. If the brakes should go out of adjustment, the push
rod must travel a greater distance than it normally would.
The push rod magnet can now get close enough to the reed
switch to close it and allow a signal to be sent to the
receiver.
2. Brake Lining Maximum Wear (Fig.4a) - An insulated
conductor wire is set into the existing brake lining.
When the lining wears off enough for the brake drum to
touch the conductor wire, a signal is sent to the receiver
in the same manner as the push rod travel signal.
3. Brake Temperature - A thermistor device or a thermo
ferrite device senses heat and begins to reduce resis-
tance. At a preset point when resistance is low enough and
the temperature has reached the danger point, the signal
will be sent to the receiver by the same signal lines that
brake lining wear or brake adjustment signals travel.
The receiver (Fig.5) has 10 Light Emitting Diodes or L.E.D.s.
Each light is designated to a vehicle axle and a particular wheel,
left or right, a piazo buzzer of a high enough decible reading to
suit the operator, a green L.E.D. light to indicate that the system
is operating, and a test circuit set of controls to test the
operation of the wheel signal switch and the receiver lights.
- 20~4334
This system will operate on all types of air brake vehicles
and will operate on trailers as an independent signal system or
incorporated in the vehicle as a signal system for tractor and
trailer(s).
The counter is there to monitor the number of brake fault
signals and will send its own signal to the electronic control
module (E.C.M.) when a preset number of faults have been counted.
This signal will tell the E.C.M. of any engine manufacturer that the
engine will begin shutting down in a sequential manner that is
already built into these units.
This counter system is an option only that may or may not be
attached to the receiver.
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A Brief Description of the Drawings
Fig.l A schematic overview of the system.
Fig.2 The complete wheel system showing the general location of
the sensors.
Fig.3 The air brake chamber in its three positi~ns:
- Brake Off #l
- Brake On (normal adjustment) #2
- Brake On (brake in need of adjustment) #3
Fig.3a A schematic of a reed switch #1 & 4, and test coil #2 & 3.
Fig.4 The brake shoe showing the sensor location.
Fig.4a A close up of the lining sensor.
Fig.4b A close up of the temperature sensor.
-
Fig.5 The receiver showing lights, buzzer and test controls.
Fig.5a The counter.
Fig.5b The ECM, Engine Control Module.
Fig.6 The automatic slack adjuster.
Fig.6b The manual slack adjuster.
Fig.7 Wiring diagram of the receiver.
- Fig.8 Buzzer wiring.
Flg.9 A schematlc of the counter and Eng~ne Control Module (ECM).
. . .
.
-^` 20~334
Background of the Invention
The present invention is directed to method and monitoring of
air brakes of a motor vehicle and/or trailer(sJ and providing a
warning signal when:
A) Brake adjustment is needed
B) Brake lining has reached its maximum wear limit
C) Brake shoe temperature has exceeded a predetermined
setting
D) The system is not operating correctly
Systems of the type A) described above are generally known to
the art and are illustrated by US Pat. No.4855712 issued to Wiley,
Jr. et al on August 8, 1989; US Patent 4757300 issued to Sebalos on
July 12, 1988. In the known systems, a permanent magnet is mounted
to the air brake chamber push rod and a magnetical-ly activated reed
switch is fixed to a permanent member of the vehicle. It can be
adjusted in such a way that if the air chamber push rod should
exceed a predetermined distance, the magnet will close the magnetic
reed switch and a signal in the form of a light and/or buzzer will
alert the vehicle operator that a problem exists.
The systems described above serve only one purpose, namely, to
indicate a need for a brake adjustment. Sebalos indicates with a
dash mounted incandescent light and Wiley gives an audible signal at
the wheel. B) & C) are not incorporated in the existing system.
In actual practise, other problems exist at the wheels:
1. The reed switch cannot be pretested before moving the
vehicle to insure that sender and receiver are working.
; .
:`
,:'
:
2~3~4
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2. With the legislated use of AUTOMATIC SLACK ADJUSTERS
(Fig.6) which are designed to automatically adjust brakes
that have come out of adjustment, these present warning
devices will be monitoring a brake problem that will never
happen. In fact, what actually happens is that the
Automatic Slack Adjusters continue to adjust the brake
shoes outward even after the linings have exceeded their
maximum wear limits. These systems will continue to
monitor tnat a problem exists but have no means of
preventing the movement of the vehicle if the problem is
not attended to.
It is the object of the present invention to provide a
reliable method and apparatus that will overcome the above disad-
vantages of the known brake monitoring systems. In particular, it
is the object of the present invention to provide a reliable method
and apparatus that will:
A) Work with standard slack adjusters and the new automatic
slack adjusters that all vehicle manufacturers are instal-
ling on their equipment and be able to pretest the
electrical system before the vehicle is moved. ~ ~
B) Monitor brake lining wear and indicate when this lining
has reached its maximum wear limits, especially useful
when automatic slack adjusters are used.
C) Monitor brake lining temperature which will indicate if a
brake shoe lining is not releasing or that a mechanical
problem other than adjustment exists.
D) As an option for trucks, this invention will count the
; number of brake faults and when a predetermined number is
reached, a signal is sent to any engine using Electronic
Control Modules or E.C.M.'s and the engine will begin a
.
. -
206~334
step-by-step shutdown process which is already built into
todays diesel engines using E.C.M.'s. In other words,
this device will eventually shut down the vehicles engine
if the original fault is not attended to.
E) This invention monitors its own circuits to ensure that
all systems work before the vehicle is put into motion.
F) This invention is installed on:
1. Trucks without trailers and buses.
2. Trucks with trailers, single, double and triple.
3. Trailers only, single double and triple.
These come under the heading of commercial vehicles.
Summary of the Invention
In accordance with the objects of the present invention, a
method and apparatus for monitoring:
(A) slack adjuster push rod travel,
(B) maximum lining wear limits, and
(C) excessive temperatures at the brake shoes,
includes a magnetically activated reed switch for (A), a lining
wear conductor wire sensor for (B), and a temperature thermistor
sensor for (C).
The monitoring of (A) includes a reed switch which is fixed to
a stationary member and has adjustment slots provided for final
adjustments and a permanent magnet mounted in a non-ferrous metal
holder which is attached to the air chamber push rod.`
During a normal air brake application, air enters the air
brake chamber and pushes the push rod and magnet out of the chamber.
1- the brake is properly adjusted, the moveable magnet wlll not
~'
.~ . .
2~5~334
reach the reaction zone of the reed switch. If, however, the brakes
become out of adjustment, the push rod will travel further than it
normally did and the magnet can now reach the reed switch reaction
area and close the switch allowing a signal to go to the receiver
indicating a brake adjustment is needed to the faulty wheel.
This system has a distinct advantage at this point over other
reed type switch units.
A coil is wrapped around the reed switch so that the operator
can pretest this switch by creating an outside means of creating
magnetism. When current is applied to this coil from the test
button or rotary switch on the receiver, magnetism is created at the
switch. This closes the reed switch and sends the signal to the
receiver. This test indicates that the reed switch is working. The
circuit wiring is complete and the indicator light for that wheel
and the warning buzzer are working. This cannot be achieved by
Wiley, U.S. Pat. #4855712 or Sebalos, U.S. Patent #4757300. The
present invention pretest is very reassuring to the operator. The
system is known to work before the vehicle is moved. This invention
uses a Hamlin Reed Switch #HE3321A1200 or a Potter & Brumfield Reed
Switch #JWS117-3, but other suitable types of reed switches could be
used by a person familiar with this field of expertise.
- 25 The monitoring of (B) includes a sensor wire that is inserted
- into the brake lining material at a specific depth. When the lining
wears off enough to expose the end of the sensor wire, a signal is
created. The sensor wire is able to reach the negative side of the
circuit by touching the brake drum and completing the fault signal
` 30 to the receiver. This indicates the need for new brake lining and a
new sensor on the faulty wheel.
;
2~33~
The monitoring of (C) includes a thermo ferrite temperature
sensor or a thermistor sensor which gives a low resistance circuit
connection to the negative side of the sensor system when a preset
temperature is reached in the brake shoe. This circuit sends a
signal to the receiver indicating a problem that requires attention,
such as a dragging brake shoe that is not releasing as well as it
should.
206~33~
- 14 -
Description of the Preferred Embodiments
Figure 2 shows a portion of an air brake of the type used
conventionally on trucks, buses and trailer units. The air brake
includes an air chamber 4 which has a housing 5 with a push rod 6
projecting therefrom. In Fig.3, the push rod has a threaded portion
at the outer end thereof which is connected to a corresponding
female threaded portion of a clevis 7. A pin 8 connects the push
rod to a brake lever 9 which shall be addressed from this point on
as a slack adjuster. The motion of the push rod will move the slack
adjuster which will rotate a shaft that is called an "S" Cam Shaft
10, Fig.2. The "S" cam, when turned, will force the brake shoes
llagainst the brake drum 12. When wear occurs at the lining 13, the
push rod must travel farther out so that the "S" cam can be rotated
an additional amount to bring the brake shoes in contact with the
brake drum. The slack adjuster contains a worm drive gear. It is
the turning of this worm gear, Fig.6b, that adjusts the brake shoes
- up to their new setting. If the brakes are properly-adjusted, the
push rod does not have to travel very far to apply the brakes,
Fig.3, #2. If the brakes are out of adjustment, the push rod must
travel much farther to make a brake application, Fig.3, #3, as the
stippled lines indicate. The present invention will send a signal
. to the operator that an adjustment is in order. This signal device
is shown in Figure 5.
Automatic slack adjusters, Fig.6A are a device that can be put
in place of the standard slack adjuster, Fig.6b. This automatic
~ adjuster will automatically make a brake adjustment by rotating the
- "S" cam in a similar way that the manual worm drive turned the "S"
cam. This automatic adjustment takes place whenever the push rod
- and slack adjuster reach the position, Fig.3, #3, shown in stippled
lines. This adjuster will continue to turn the "S" cam each time
the stippled line #3 position is reached. This will continue
without stopping until all the lining is worn from the shoe and
metal to metal contact is made. The present invention will prevent
.
20~33~
this from happening because a lining wear signal device shown in
Fig.4a will warn the operator of this.
Occasionally, the "S" cam, Fig.2, #10, will turn and apply the
brake and become seized in this position because of outside sources
such as salt water, ice, or sand causing binding to the "S" cam
shaft. When the brake shoes cannot release themselves from the
brake drum, there will be excessive heat buildup at this wheel. The
present invention will prevent serious damage to the brake linings
and drums by indicating through conductor wire, Fig.4, #14, to the
operator that a dragging brake exists. This indicator is shown in
Figure 4a.
Figure 3, THE PUSH ROD TRAVEL SENSOR.
A permanent magnet which is mounted to the push rod~6 and is
; supported in a non-magnetic tube~6 such as copper or any other
non-ferrous metal moves when the push rod moves. Attached to one of
the brake chamber mounting studs is a bracket~l7. This bracket
- 20 supports a non-magnetic housing ~18, in this case it is plastic.
This housing surrounds the copper tube and guides the magnet to
insure accurate movement. The plastic housing contains a standard
magnetically activated switch~l9 as, for example, a reed switch or a
transducer switch.
This plastic housing is adjustable and can slide to and fro by
slots in the bracket assembly~7. The bracket is secured with
non-magnetic means such as stainless steel machine screws or plastic
strapping.
- The magnetically activated switch, Fig.3a, has a coil wrapped
around it that, when electrically activated by a rotary switch or
push button~ at #22, will create a magnetic field around the switch.
If the switch is working properly, it will close and send a signal
through conductor wire~23 to the vehicle operator. This present in-
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~ 2~334
- 16 -
vention can be tested for the proper operation of its circuits
before the driver begins the trip by closing the reed switch with
the test coil. In this present invention, we are using a Hamlin
Switch #HE 3321A1200, a Potter & Brumfield Reed Switch #JWS117-3 or
any other similar switch. These switches have the coil built into
them allowing the pretest coil to be built right into the assembly.
They operate at a temperature range of -45C to +lOOC.
In a normal brake application, the push rod 6 and magnet #15
will extend outwards from the chamber~5. The magnet will stop
moving before it reaches the switch. In an abnormal situation where
the brakes require adjustment, as shown in stippled lines*3, the
magnet can reach the active area of the switch~l9 and will close it.
This circuit will then send its signal to the operator through
- 15 conductor wire~23, Fig.3.
Figure 4 shows the BRAKE LINING WEAR INDICATOR.
The brake shoe lining has a conductor wir ~14 inserted into it
to a depth that maximum lining wear will be allowed to take place.
This indicator is activated when the conductor wire in the
brake lining~l3 can touch the brake dru ~12.
.~
When this happens, a signal will be sent through the same
circuitry that the brake adjustment signal travels and will indicate
to the operator that repairs are necessary (in this case, not a
brake adjustment).
Figure 4b shows the TEMPERATURE SENSING SENDER.
A thermistor sender is installed on the metal area of the
brake shoe. If excessive brake friction should exist, such as a
2064334
- 17 -
dragging brake, the indicator will sense a large drop in resistance
and will send a signal, through the same circuitry as Figure 4 and
Figure 3, to the operator that repairs are needed.
To determine which sensor, Figure 3, Figure 4, or Figure 4b is
at fault, each wire~23,*24 ord~25 from each sensor can be unplugged
from its quick connector. When a sensor is disconnected that is
faulty, the signal light and buzzer, Fig.5, located where the
operator can see it, will go out. These sensors are easily replaced
when repairs are completed.
THE INDICATING RECEIVER, Figure 5.
The present invention has a receiver to gather these sender
signals. The receiver contains 10 red light emitting diodes or
L.E.D.s, a coil test rotary knob or button~P27. A green L.E.D.
~28indicates if the system has power.
. .
12 volt to 15 volt power for this receiver can be obtained in
various ways:
: - The ignition switch, if the receiver was in the cab.
- The brake light conductor wire that presently exists
` on all trailers.
- The clearance light conductor wire that presently exists
on all trailers.
~ - Brake and/or clearance light can be used but requires
; an orgate switch.
One receiver unit will handle 5 vehicle axles with a separate
L.E.D. for left and right side for a total of 10 L.E.D.s. If
morethan 5 axles are used, another receiver unit system can be
coupled in tandem with the first receiver. These additional
receivers can be added to accommodate any number of vehicle axles.
For example, receiver #1 handles axles 1,2,3,4, and 5. Receiver #2
handles axles 6,7,8,9, and 10 and so on with receiver #3.
-`` 20~33~
T0 SUM UP:
The receiver is able to tell the operator that it is on by
indicating with a green L.E.D~28 that is always on if the power
- 5 supply is there.
The receiver will indicate which axle is at fault and whether
it is the left side or the right side by indicating with one of 10
red L.E.D. 1ights~26.
The receiver can pretest all of the circuitry in the system
with a rotary selector switch or a push button switch~27 which will
send current to the test coil of all the brake adjust~ent switches.
If all the L.E.D.s in the receiver light, then all circuits are
working in that system.
.
The receiver gives an audible signal whenever a red L.E.D.
comes on. This present invention uses a piazo busser~29 or a
. standard 12 volt buzzer with sufficient decibles to alert the driver
of a problem.
An optional extra counter, Fig.5a, is used on this present
invention which will count the number of times the red L.E.D.'s have
come on. A preset figure can be put into this counter and when this
number is reached, because the operator ignored the red L.E.D.s, it
sends a signal to the Electronic Control Module that modern day
diesel and gas engines use and the system that was installed by the
- engine manufacturer will shut the engine down in a series of steps
to give the operator time to reach a suitable place to park.
It is evident that other modifications and variations within
the scope of the invention described herein will beco~e apparent to
those skilled in the art. The embodiments of the invention des-
2~6433~
- 19 -
above are intended to illustrate only, and not restrictive of the
scope of the invention, that scope defined by the following claims
and all equivalents thereto.
