BRAKE MONITORING SYSTEM AND METHOD
FIELD OF THE INVENTION
The present invention relates to motor vehicle braking systems generally and
more particularly to the detection of overheating of brakes, especially of trucks and
other heavy vehicles.
BACKGROUND OF THE INVENTION
Motor vehicles and especially trucks, trailers, buses and other heavy vehicles
are subject to intensive use of their brakes. It is common practice for truck drivers to
overuse their brakes. For example, when traveling downhill, drivers are apt to
continually press the brake pedal instead of selecting a lower gear for braking to slow
their vehicle. Continuous friction between the brake pad and its drum causes
overheating which leads to a loss of efficiency in the braking system. Ultimately,
overheating may lead to a partial or complete braking failure and subsequently to a
major and fatal road accident.
Heavy vehicles are disproportionately responsible for road accidents. Among
these road accidents a significant proportion are due to faulty or incorrect use of the
vehicle's brakes. "Brake" accidents may be minimized by early detection and
notification to the driver of any abnormal or dangerous situation, such as overheating.
Furthermore, driving habits can be improved by tracking and monitoring a driver's
braking performance.
Numerous brake detectors and systems for the surveillance of brakes are
known. For example, U.S. Pat. No. 4,649,370 to Thomason describes a brake
condition indicator which is attachable to a conventional brake shoe. U.S. Pat.
1
SUBSTITUTE SHEET (BULE 26)
No. 5,302,940 to Chen describes a motor vehicle brake detector which is fastened in
the brake shoe and includes a blind hole formed in the brake shoe.
U.S. Pat. No. 4,820,257 to Berndt describes a method and apparatus for
contactless measuring of the brake temperature of passing railroad cars by fixing
sensor apparatus to the rail track to scan the passing wheels.
For maximum efficiency, such stationary detection equipment needs to be
placed at regular intervals. Unfortunately, a high percentage of rail vehicles are
missed and axle-journal breakages constantly recur.
The known prior art devices require modification of existing braking systems.
Such modification tends to be costly and impractical for large vehicle fleets.
Additionally, prior art devices are difficult to replace and maintain and are detrimentally
affected by oil and dirt.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a brake temperature detection
unit which overcomes the limitations and disadvantages of prior art units.
A further object of the present invention is to provide a brake temperature
detection unit which is easily and quickly installed.
A yet further object of the present invention is to provide a brake temperature
detection unit which does not require major modifications to the vehicle.
A yet further object of the present invention is to provide a brake temperature
detection unit which uses radiation sensors.
A yet further object of the present invention is to provide a brake temperature
detection unit which is automatically cleaned.
There is thus provided, in accordance with a preferred embodiment of the
present invention, a brake monitoring system having at least one brake temperature
detection unit externally attached to one of the brake assemblies of a vehicle. The
brake temperature detection unit includes at least one sensor for detecting radiation
from the corresponding brake assembly.
Additionally, in accordance with a preferred embodiment of the present
invention, there is provided a brake temperature detection unit externally attached to
one of the brake assemblies of a vehicle. The brake temperature detection unit
includes at least one sensor for detecting radiation from the corresponding brake
assembly and a processing unit coupled to the sensor for determining the temperature
of the corresponding brake assembly from the detected radiation.
Furthermore, in accordance with a preferred embodiment of the present
invention, the system further includes a processing unit for determining the
temperature of the corresponding brake assembly from the detected radiation. The a
processing unit is coupled to each of the brake temperature detection units.
Furthermore, in accordance with a preferred embodiment of the present
invention, the system further includes control apparatus coupled to the brake
temperature detection unit and to the a processing unit.
Furthermore, in accordance with a preferred embodiment of the present
invention, upon the recorded temperature of the corresponding brake assembly
exceeding a pre-determined level, the control apparatus causes the vehicle to be
brought to a halt.
Furthermore, in accordance with a preferred embodiment of the present
invention, the control apparatus includes means for indicating to the driver of the
vehicle whenever the recorded temperature of the corresponding brake assembly
exceeds a pre-determined level. The indication includes an audible alarm or at least
one LED light corresponding to each of the at least one brake temperature detection
units.
Furthermore, in accordance with a preferred embodiment of the present
invention, the brake temperature detection unit further includes a housing having an
aperture formed in one side thereof. The brake temperature detection unit is fitted to
the vehicle brake assembly so that the aperture is in alignment with the brakes of the
vehicle brake assembly and the sensor.
Additionally, in accordance with a preferred embodiment of the present
invention, the brake temperature detection unit further includes a heat source and a
second sensor coupled to the heat source.
Furthermore, in accordance with a preferred embodiment of the present
invention, the brake temperature detection unit also includes a mirror shutter unit
pivotally fitted to the brake temperature detection unit, whereby the mirror shutter unit
is movable from a first position wherein the mirror shutter unit sealingly closes the
aperture to a second position wherein the mirror shutter unit reflects radiation from the
heat source.
Furthermore, in accordance with a preferred embodiment of the present
invention, the mirror shutter unit is operable by means of an electromagnet attached to
the mirror.
Additionally, in accordance with a preferred embodiment of the present
invention, the brake temperature detection unit also includes filtration means.
Furthermore, in accordance with a preferred embodiment of the present
invention, the control apparatus includes a black box device. The black box device
includes a memory storage device coupled to the a processing unit, a processor
connected to the memory storage device and a recording device connected to the
processor.
Additionally, in accordance with a preferred embodiment of the present
invention, there is provided a method for detecting an increase in temperature in a
vehicle brake assembly having a brake temperature detection unit fitted thereto. The
method includes the steps of:
a) determining the ambient temperature of the detecting unit;
b) determining the temperature of a heat source within the detecting unit, the
detecting unit being sealed from any radiation from the brake assembly;
c) recording the temperature of the brake assembly;
d) comparing the recorded brake assembly temperature with the determined
heat source temperature; and
e) indicating an alarm if the recorded brake assembly temperature exceeds a
pre-determined temperature.
Furthermore, in accordance with a preferred embodiment of the present
invention, the pre-determined temperature is equal to the determined heat source
temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and appreciated more fully from the
following detailed description taken in conjunction with the appended drawings in
which:
Fig. 1 is a sectional elevation of a brake temperature detection unit, constructed
and operative in accordance with a preferred embodiment of the present invention;
Fig. 2 is a schematic illustration of the brake temperature detection unit of Fig.
1 , fitted to a vehicle;
Fig. 3 is a schematic illustration of a typical 6-wheeled vehicle having a
temperature detection unit of Fig. 1 , fitted to each brake assembly;
Fig. 4 is a schematic block diagram illustration of the electronic and mechanical
components of a brake temperature detection unit constructed and operative
according to a preferred embodiment of the invention;
Fig. 5A s a schematic arrangement of a control box operable with a brake
temperature detection unit of Figs 1 and 4;
Fig. 5B is a front elevational view of the control box of Fig. 5A;
Figs. 6A and 6B are side and plan elevational views, respectively, of a brake
temperature detection unit, constructed and operative according to further preferred
embodiment of the invention;
Fig.7 is a schematic block diagram illustration of the electronic and mechanical
components of the brake temperature detection unit of Figs 6A and 6B; and
Fig. 8 is a flow chart illustration of the operation of brake temperature detection
unit
DETAILED DESCRIPTION OF THE PRESENT INVENTION
Reference is now made to Figs. 1 , 2 and 3. Fig. 1 is a sectional elevation of a
brake temperature detection unit, generally referenced 10, constructed and operative
according to a preferred embodiment of the present invention. Fig. 2 illustrates brake
temperature detection unit 10 fitted to a standard brake assembly, generally
designated 12, of a vehicle. The brake temperature detection unit 10 is fitted to the
standard brake assembly 12 to detect changes in the temperature of the brake
assembly 12. In a typical arrangement, illustrated in Fig. 3 and constructed and
operative according to a preferred embodiment of the present invention, a separate
detection unit 10 is fitted to each of the brake assemblies of a 6-wheeled vehicle.
Each of the detection units 10 are coupled to a central control box 14, which is
preferably located within the vehicle driver's cab for ease of access and display.
Brake assembly 12 is any standard braking unit fitted to vehicles and comprises
a brake cover 16 enclosing a brake drum 17 and brake pads 18. The brake covers of
standard brake assemblies generally have an opening, referenced 20, formed therein,
which allows the brake pads 18 to be viewed without the necessity of removing the
cover 16. The present applicants have realized that the temperature within the brake
assembly 12 can be monitored by attaching a detection unit which surrounds the
brake drum opening 20.
Brake temperature detection unit 10 comprises a housing 22 and an adapter
24. Housing 22 comprises a generally box-like structure having a projecting element
26Λ protruding from one side thereof. An aperture 28 is formed within projecting
element 26.
Adapter 24 is bolted, or otherwise suitably fitted, to brake cover 16. The
housing 22 of brake temperature detection unit 10 is suitably attached to adapter 24.
A second opening 25 is formed in adapter 24. Second opening 25 has
generally similar dimensions to opening 20 in brake cover 16 and to aperture 28 of
housing 22. Brake temperature detection unit 10 is fitted to brake cover 16 via adapter
24 so that opening 20, aperture 28 and second opening 25 are aligned. Thus,
radiation has unimpeded access to housing 22.
Brake temperature detection unit 10 further comprises a sensor 30 attached to
a central processing unit (CPU) 32, at least one heat source 34, a mirror shutter 36, a
fan 38 and at least one air filter unit 40.
Sensor 30 is any suitable sensor capable of recognizing changes in
temperature, such as infra-red (IR) sensors. Sensor 30 is located, within the
projecting element 26 of housing 22, directly opposite aperture 28 in order to be able
to perceive temperature changes occurring due to the application of the vehicle's
brakes.
CPU 32 is any known in the art processor which is also coupled to heat source
34 and fan 38.
Heat source 34 is any suitable heat element preferably coupled to a thermistor
35 (Fig. 4) or similar resistor. Heat source 34 provides a pre-determined reference
temperature for sensor 30.
Mirror shutter 36 is pivotally fitted to one corner 42 of projecting element 26. In
the preferred embodiment of Fig.2, detection unit 10 further comprises an
electromagnet 44 (Fig. 1) which is coupled to CPU 32. Mirror shutter 36 is operated
by means of electromagnet 44 to open and close aperture 28. Mirror shutter 36 acts
in a manner similar to a shutter device in a camera, that is, it can be opened to allow
radiation to enter housing 22. When in its default inactive and closed position, mirror
shutter 36 seals the unit 10 and prevents any radiation from entering the unit 10.
Fan 38 is any suitable fan for providing circulation and cooling within housing
22. Air filter 40, which is any suitable filter for filtering the air and preventing dust from
entering housing 22, is located at the far end of housing 22Λ distal from sensor 30.
Thus, continuously filtered air (via air filter 40) circulates through housing 22 and exits
via aperture 28.
Reference is now also made briefly to Fig. 4, which is a schematic block
diagram illustration of the electronic and mechanical components of a preferred
embodiment of detection unit 10 utilizing a second sensor 46. Detection unit 10
further comprises a differential amplifier 47, an amplifier 48 and a voltage regulator 49,
all of which components are suitably coupled to CPU 32. Differential amplifier 47,
amplifier 48 and voltage regulator 49 are standard known in the art devices.
Second sensor 46, which is similar to sensor 30, is located adjacent to sensor
30. Sensor 30 lies in direct line of radiation (indicated by rays 45), produced by heat
generated from the brakes 18. Sensor 46, which is covered up so as not to be
exposed to any external radiation, records the temperature of the thermistor 35 of heat
source 34. Thus, the temperature recorded by sensor 46 provides a reference
reading. Differential amplifier 47 which is coupled to both sensors 30 and 46, amplifies
the difference in temperature readings recorded by each of the first and second
sensors 30 and 46, respectively. The resulting reading is further amplified by amplifier
48 and the analog signal converted to digital format for processing by CPU 32.
Voltage regulator 49 is used to reduce the input from the main connection 51,
which preferably is a standard 12V vehicle battery, to 5V which is required to operate
detection unit 10.
Reference is also now made to Fig. 8, which is a flow chart illustration of the
operation of brake temperature detection unit 10. Mirror 36 is closed (its default state)
and the voltage resistance (say vis and v1h) are recorded by sensors 30 and 46.
respectively (step 202). The suffix "s" refers to sensor 30 and the suffix "h" refers to
sensor 46. The ray (referenced 70) produced by heat source 34, is reflected by mirror
36 and the reflected ray (referenced 71) is detected by first sensor 30. Sensor 46
directly records the voltage of thermistor 35. When the mirror is closed, and there is
not any IR radiation entering housing 22, the readings from sensors 30 and 46 may be
similar and thus, the difference recorded by differential amplifier 47 should be close to
zero. The temperatures (say t1s and t1h) corresponding to the sensor readings 30 and
46, respectively, are calculated (by CPU 32) from the voltage readings (step 204).
Temperatures t1s and t1h vary and are dependent on the ambient temperature within
the unit 10. The sensitivity of sensor 30 depends on the ambient temperature.
Heat source 34 is actuated to generate heat (step 206) and the voltages (say
v2s and v2h) are recorded by sensors 30 and 46, respectively (step 208). The
corresponding temperatures (say t2 and t2h) are then calculated (step 210) . Since
the temperature (t2t) of heat source 34 is known, it can be used to calibrate the sensor
30. For example, if heat source 34 generates a temperature of 100°C and sensor 30
records a temperature equivalent to 96°C, then all readings by sensor 30 can be
adjusted accordingly.
Mirror 36 is actuated to its open position by means of electromagnet 44 (step
212) The temperature of the brake assembly 12 is constantly monitored by sensor 30
and processed by CPU 32 (step 214) The difference in the IR readings from sensors
30 and 46 increases according to the increase of external IR radiation. The differential
data is amplified (by amplifiers 47 and 48) and after processing by CPU 32 is output to
control box 14 where the data is stored (step 216) If the temperature of any of the
brake units exceeds the pre-determined maximum (which may be equal to the
recorded heat source temperature), an alarm is indicated to the driver (step 218). The
alarms may be audible or visual. The data is also stored in the "black box" storage
unit (step 220).
Each of the detection units 10 can be independently operated and monitored.
In a preferred mode of operation, all of the detection units 10 work simultaneously
transmitting data to the control box 14.
Reference is now made briefly to Figs. 5A and 5B. Fig. 5A, is a schematic
arrangement of control box 14 and Fig. 5B is a front elevational view of control box 14
Control box 14 comprises a main processor 50 to which is coupled the data input
connections, referenced 52, from each of the detection units 10 fitted to the vehicle's
brake assemblies. Control box 14 further comprises a memory storage device 54, an
alarm indicator 56, a processor 57 and preferably a date and time recording device 58,
all of which components are coupled to main processor 50.
The memory storage device 54, processor 57 and recording device 58
components are preferably comprised within a "black box" device 60 (shown by
dashed lines). Optionally, a display console 62 is coupled to main processor 50.
Preferably, a backup battery 64 is also coupled to the processor 50 to ensure
continuous power supply in the event that the vehicles' main battery is inoperable,
Main processor 50 and the various components of the control box 14 are
standard, known in the art components. The alarm indicator 56 is any suitable audible
indicator, such as, a buzzer which can appraise the driver of the increase in brake
temperature due to over-heating or brake failure.., Additionally, a plurality of LED lights
59, one for each detection unit 10, indicate whenever the brake temperature exceeds
a safe figure in order to give the driver advance warning of potential failure.
Alternatively, different LED lights of different colors or different sounding alarms may
be used to indicate gradually increasing brake temperatures.
The "black box" device 60 is a known sealed storage device for storing and
maintaining records and is capable of withstanding extreme environmental conditions.
The data stored within black box 60 can be used for investigative purposes, for
example, to determine events leading up to a fatal accident.
The control box 14 is preferably connected to the vehicle's ignition and braking
system so that in the event of excessive temperatures being recorded or a brake
failure detected, the vehicle can be brought to a halt and rendered inoperable until the
cause of the failure is corrected.
Reference is now made to Figs. 6A, 6B and 7. Figs. 6A and 6B are side and
plan elevational views, respectively, of a brake temperature detection unit, generally
referenced 100, constructed and operative according to a further preferred
embodiment of the invention. Fig. 7 is a schematic block diagram illustration of the
electronic and mechanical components of a brake temperature detection unit 100.
Elements of this embodiment of the invention which are similar to elements
which have been previously described with respect to the preferred embodiment
hereinabove, are similarly designated and will not be further described.
Brake temperature detection unit 100 comprises a housing 102 and an adapter
(not shown) similar to adapter 24 (Fig. 2). Housing 102 is similar to housing 22 and
comprises a generally box-like structure having a projecting element 104 protruding
from one side thereof. An aperture 106 is formed within projecting element 104.
Brake temperature detection unit 100 is fitted to brake cover 16 via adapter 24
so that aperture 106 is aligned with the opening (20) in brake cover 16.
Brake temperature detection unit 100 comprises first and second sensors
sensor 30 and 46, respectively, a mirror 36, a lens 105, fan 108, first and second filter
units 110, first and second amplifiers 112, a heat source 114 and a third amplifier 48.
All of these components are suitably coupled to CPU 32.
Sensors 30 and 46, which preferably are infra-red (IR) sensors, are located
within housing 102 so that sensor 30 is directly opposite aperture 106, in order to be
able to perceive temperature changes occurring in the brake assembly 12 (Fig. 2).
Lens 105 concentrates the radiation form the brakes onto sensor 30.
In this embodiment, aperture 106 is continuously open to the elements. An
electromagnet is not used to open and close the mirror so as to occasionally seal the
housing 102. In order to compensate for the increased amount of air and dust likely to
enter aperture 106, filter units 110 are placed on either side of sensors 30 and 46.
Fan 108 is located proximate to mirror shutter 36 to keep it clear of dust and dirt.
It will be appreciated by persons skilled in the art that any suitable method of
attaching housing 20 and 102 to adapter 24 may be used. In accordance with a
preferred embodiment of the invention, the method of attachment preferably allows
detection unit 10 to be removed for maintenance. For example, housings 22 and 102
may comprise a spring-loaded device having clips which can hook onto and
encompass matching clips formed on adapter 24.
It will be appreciated that the present invention is not limited by what has been
described hereinabove and that numerous modifications, all of which fall within the
scope of the present invention, exist. For example, while the present invention has
been described with respect to the use of double IR sensors, the temperature of a
vehicles braking system may be detected using any combination of suitable sensors.
Furthermore, it will be appreciated that there are numerous alternative methods
of keeping the mirror and sensors clean. For example, a wiper system, similar to that
employed for cleaning vehicle windscreens or headlights, can be attached to the brake
temperature detection unit. Alternatively, an air pressure system can be attached to
keep the mirror and sensors clean.
It will be appreciated by persons skilled in the art that the present invention is
not limited to motor vehicles and may be adapted for use in other modes of
transportation, especially railroads and airplanes. For example, the detection units
may be fitted to railroad car brakes, wheels, tires and axle bearings. By means of a
suitably configured control panel, a locomotive driver could be kept appraised of all the
relevant railroad components which are subject to overheating and damage.
It will be appreciated by persons skilled in the art that the present invention is
not limited by what has been particularly shown and described hereinabove. Rather
the scope of the invention is defined by the claims which follow: