CA2064334A1 - Commercial vehicle wheel monitoring device - Google Patents

Abstract

COMMERCIAL VEHICLE
WHEEL MONITORING DEVICE

Abstract The method and apparatus provides an improved system for moni-toring air brakes of a commercial vehicle. The system monitors brake temperature, brake lining wear limits and brake adjustment.
It can be installed on all commercial vehicles and can operate on trailers as a system within itself. This becomes very important when trailers are shuffled from one towing vehicle (tractor) to another. This system can be tested for operation before the vehicle is put in motion. It will indicate any of the above problems, namely, lining wear limits, brake adjustment and heat build up and will indicate with a buzzer and a light at a receiver exactly which wheel is faulty in the system.

A means of counting the faulty brake applications each time the brake pedal is depressed can be added to this system. This counter will monitor a preset number of brake applications and will send a signal to any engine having electronic controls. This signal will put the engine control module into an emergency shut down mode if the problem at the wheel is not rectified.

Description

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.

- 206~334 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).

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-^` 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.

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2~3~4 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.

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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.

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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 .

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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-~ , .

~ 2~334 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.
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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 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.
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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.

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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.
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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~

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.

Claims (22)

1. In a system for monitoring the condition of air brakes in a motor vehicle using a switch means coupled to an alarm means and a switch actuator coupled to the vehicles braking system, the improvements comprising:

Fig.3a, a coil surrounding said switch that will facili-tate the testing of the entire circuitry at the receiver and all the conductor wiring down to and including the said switch.

2. The system of claim 1 to include a system of measuring brake lining wear, Fig.4a.

3. The system of claim 2 to include a system of measuring brake shoe temperature, Fig.4b.

4. The system of claim 1 wherein said switch is including a magnetically activated switch, a test coil, and a permanent magnet, Fig.3.

5. The system of claim 1 has a non-magnetic holder so that the relationship of the permanent magnet and the magnetically activated switch with test coil will always remain at close tolerances to one another, Fig.3, #16 & #18.

6. The system of claim 4 wherein said permanent magnet is mounted at the locking nut#30 of the push rod yoke or clevis and is encased in a non-magnetic tube.

7. The system of claim 5 wherein said holder contains the magnetically activated switch, the test coil and the signal input plugs for brake shoe temperature and lining wear limits.
These signals all join at conductor wire #23.

8. The system of claim 2 includes an insulated conductor wire#14 with its sensor end exposed and is set into the brake lining at a specified depth so that the sensor end will be exposed when maximum lining wear is reached.

9. The system of claim 3 has a thermo-ferrite switch or a thermistor switch, Fig.4b, attached to the brake lining shoe that will be normally open and will close when present abnormal temperatures are sensed.

10. The system as claimed in claim 1 wherein the signaling device (receiver), Fig.5, includes light emitting diodes#26 for each wheel and a buzzer#29 audible signal.

11. The system as claimed in claim 1 wherein the signaling device (receiver), Fig.5, has a button#27 or rotary switch that will direct test current to the test coil#22 in the brake adjustment sensor. If an L.E.D. (light emitting diode) and/or a buzzer audible signal is heard, we have learned that the system is functional.

12. The system has an electonic or mechanical counter, Fig.5a, that will record each light or buzzer signal when the vehicle is in motion only.

13. The system as claimed in claim #12 will have an adjustable setting that will send a fault signal to the engine's electronic control module, Fig.5b, when this setting has been reached.

14. The system as claimed in claim #13 will send its signal to the spot on the electronic control module that sets the system at the ENGINE GRADUAL SHUT DOWN MODE.

15. A method of monitoring the condition of the brake assembly's signals including the steps of:

a system that can be mounted on trailers only whereby the system shall receive its power from the trailer's brake light system and/or running light system.

16. The method of claim #15 is activated by a magnetically activated switch that includes a test coil to pretest the system.

17. The system as claimed in claim #15 has its indicating light emitting diodes and buzzer mounted on that system's trailer at a point that can be easily seen by the operator's rear view mirror.

18. The system in claim #15 includes the steps of:
a system of monitoring the towing vehicle (tractor) from the cab of the vehicle where the operator can see and hear it.

19. The system in claim #18 includes the steps of:
a system of monitoring trailers from the cab of the towing vehicle.

20. The system has plug in sensors, namely:
- Brake adjustment - Brake lining wear - Brake shoe temperature - A counter to record faults when the vehicle is moving - A signal set from the counter to the vehicle's engine control module.
Any or all of these sensors can be used at one time.

21. The system's circuitry is wired in such a way that the system could have:
- The receiver in the cab of the truck.
- The receiver in the cab for the trailers(s).
- The receiver(s) at the trailers(s) only.

22. The system's circuitry is wired in such a way that any number of 5-axle monitors can be connected in a series so that any multiple of axles can be monitored by coupling two or more complete units together.