Patent Application
20140200761
The present invention relates to a brake monitor. It finds particular application in conjunction with monitoring service brakes on heavy vehicles and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
Heavy-duty trucks, buses, and other large vehicles are typically equipped with a pneumatic brake actuating system. When a service brake pedal is depressed by an operator of the vehicle, the brake actuating system typically applies air under pressure to a plurality of service chambers, which cause respective push rods and diaphragms to move. Each of the push rods is connected to a respective linkage for actuating an associated service brake on the vehicle. Each push rod has a predetermined range of available movement (e,g., stroke).
Excessive movement or stroke of the push rod may be created by various factors. Typically, such excessive movement is due to brake lining wear. For example, as the brakes wear, more movement of the push rod is required to actuate the brakes. Further, over time the linkages and connections between the push rod and the linkages may bend, become loose, or excessively worn, which may require additional push rod stroke to actuate the brakes. One or more of these factors may cause the amount of push rod movement required to actuate the brakes to approach the maximum push rod stroke available from the brake actuator.
In other situations, a service brake may remain stuck in the applied or partially applied position even after the service brake pedal is released. With a service brake stuck in the applied position, the associated push rod likely will not return to its anactuated position.
For the reasons discussed above, it may be desirable to monitor the movements and positions of the respective push rods, either directly or indirectly.
The present invention provides a new and improved apparatus and method which addresses the above-referenced problems.
In one embodiment, a brake chamber includes a housing defining, a service air brake volume. A diaphragm is associated with a plate that is movably secured within the housing. The diaphragm divides the service air brake volume into a pressure portion and a non-pressure portion. Respective volumes of the pressure portion and the non-pressure portion change as the diaphragm moves within the housing. A sensor is in the service air brake volume. Electronics, associated with the sensor, determine a position of the plate in the housing.
In the accompanying drawings which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify the embodiments of this invention.
With reference to
An electronic control unit (ECU) 22 electronically controls the brake actuators 16 via electro-pneumatic devices, such as modulators and traction relay valves, for applying and releasing, the service brakes under different conditions. For example, the ECU 22 may control one or more of the brake actuators 16 to cause respective ones of the service brakes to alternately be applied and released during an anti-lock braking event. In another example, the ECU 22 may control one or more of the brake actuators 16 to cause respective ones of the service brakes to be applied for reducing the chance of a roll event.
With reference to
The brake actuator 16 includes a brake chamber housing 24, which defines a service brake volume 26 (e.g., a service brake chamber) and a parking brake volume 30 (e.g., a parking brake chamber). A service volume diaphragm 32 is associated with a plate 33 that is movably secured within the service brake volume 26. A parking volume diaphragm 34 is associated with a plate 35 that is movably secured within the parking brake volume 30. The service volume diaphragm 32 is associated and moves with the plate 33. The parking volume diaphragm 34 is associated and moves with the plate 35. In
The service brake volume 26 is sealingly divided by the service volume diaphragm 32 into two (2) sides (e.g., portions) a pressure side 36 (e.g., a pressure portion) and a non-pressure side 40 (e.g., a non-pressure portion). The non-pressure side 40 of the service brake volume 26 is maintained at atmospheric pressure. The pressure side 36 of the service brake volume 26 receives the pressurized fluid from at least one of the reservoirs 12 (see
A sensor 42 (e.g., an optical sensor) is included within the brake chamber housing 24. In one embodiment, the sensor 42 is included in the service brake volume 26. In the illustrated embodiment, the sensor 42 is included on the non-pressure side 40 of the service brake volume 26. For example, the sensor 42 is positioned proximate to a wall 44 of the brake chamber housing 24 across from the service volume diaphragm 32. It is contemplated that the sensor 42 is immovably secured proximate to a wall 44 of the brake chamber housing 24. However, it is to be understood that the sensor 42 may be easily accessible for servicing and/or replacement.
With reference to
The sensor 42 includes electronics 52, which electrically communicate with a connector 54. The connector 54 electrically communicates with as vehicle communication bus 56, which electrically communicates with the ECU 22. The sensor 42 is capable of transmitting signals (e.g., message signals) to the ECU 22 via the vehicle communication bus 56. In one embodiment, the electronics 52 associated with the sensor 42 determine if the service volume diaphragm 32 (and the plate 33) is in the Brake On or the Brake Off position. The message transmitted by the sensor 42 to the ECU 22 identifies the Brake On or Brake Off information. It is also contemplated that the sensor 42 is capable of receiving signals. (e.g., message signals) from the ECU 22 via the vehicle communication bus 56. Alternatively, the sensor may be connected directly to the ECU 22,
With reference to
In the illustrated embodiment, the image received at the sensor 42 in the step 112 includes position information e.g., the marks 50 of the pattern 46) and indicates a position of the service volume diaphragm 32 (and the plate 33) in the housing 24. As illustrated in
It is contemplated that the light may be visible light or infrared light. It is also contemplated that instead of transmitting and receiving light the signal sensor 42 may transmit and receive an ultrasound signal. In this case, the sensor 42 may determine the distance between the sensor 42 and the service volume diaphragm 32 (and the plate 33) based on a time delay between when the sound signal is transmitted in the step 110 and when the reflected signal is received back at the sensor 42 in the step 112. The position of the service volume diaphragm 32 (and the plate 33) within the service brake volume 26 is then determined in the step 114 by the sensor electronics 52 based on the distance of the service volume diaphragm 32 (and the plate 33) from at least one of the sensor 42 and the wall 44 of the brake chamber housing 24.
In one embodiment, the sensor electronics 52 receives a message from the ECU 22 indicating a level of service brake demand in a step 116. For example, if the operator of the vehicle is not currently depressing the service brake pedal 14, the message from the ECU 22 to the sensor electronics 52 indicates no service braking is demanded. If the operator of the vehicle is currently depressing the service brake pedal 14 about one-half of a maximum distance, the message from the ECU 22 to the sensor electronics 52 indicates about one-half of a maximum service braking, is demanded. The operator of the vehicle is currently depressing the service brake pedal 14 about the maximum distance, the message from the ECU 22 to the sensor electronics 52 indicates about the maximum service braking is demanded. The ECU 22 can infer brake imbalance from more than one sensor 42. The optical sensor alone can infer contamination in the brake chamber if the image is blurry. The sensor 42 can also infer brake chamber pressure with a known volume.
In this embodiment, the sensor electronics 52 are calibrated to identify expected positions (e.g., baseline positions) of the respective service volume diaphragms 32 (arid plates 33) based on the level of service brake demand (e.g., based on a position of the service brake pedal 14). The sensor electronics 52 compare the position of the service volume diaphragm 32 (and plate 33) within the respective service brake volume 26 with the expected position in a step 120, if the position of any of the service volume diaphragms 32 (and plates 33) is not within a predetermined tolerance of the expected position (e.g., if any of the service volume diaphragms 32 (and plates 33) remain, or “stick”, in the Brake ON position for applying the associated service brake even after the service brake pedal 14 is released), the respective sensor electronics 52 transmit a message to the ECU 22 for alerting the vehicle operator in a step 122. For example, the ECU 22 may alert the driver by illuminating a dashboard light and/or sounding a buzzer in the operator cab. Therefore, in this embodiment, the sensor electronics 52 determine the position of the service volume diaphragm 32 (and plate 33) within the respective service brake volume 26.
In another embodiment, the sensor electronics 52 transmit a message to the ECU 22 indicating the position of the service volume diaphragm 32 (and plate 33) within the service brake volume 21 in a step 130. It is contemplated that the ECU 22 may receive messages from a plurality of respective ones of the sensor electronics 52 in a step 132. Upon receiving the respective messages from the sensor electronics 52, the ECU 22 identities the positions of the service volume diaphragms 32 (and plates 33) within the respective service brake volumes 26 in a step 134.
The ECU 22 may compare the positions of the service volume diaphragm 32 (and plate 33) with the expected positions (e.g., baseline positions) of the respective service volume diaphragms 32 (and plates 33) based on the level of service brake demand in a step 136. If the ECU 22 determines that the position of any of the service volume diaphragms 32 (and plates 33) is not within a predetermined tolerance of the expected position, the. ECU 22 transmits a message to the vehicle communication bus 56 for alerting the vehicle operator in a step 140.
Alternatively, the ECU 22 may compare the positions of the respective service volume diaphragms 32 (and plates 33) with the positions of the other service volume diaphragms 32 (and plates 33) in a step 142. For example, if the ECU 22 determines that the position of any of the service volume diaphragms 32 (and plates 33) is not within a predetermined tolerance of an average position of all of the service volume diaphragms 32 (and plates 33) and/or a tolerance of the positions of one or more of the other service volume diaphragms 32 (and plates 33) the ECU 22 transmits a message to the vehicle communication bus 56 for alerting the vehicle operator in the step 140.
Although the illustrated embodiment includes the sensor 42 in the housing wall 44 on ton-pressure side 40 of the service brake volume 26, it is contemplated that the sensor 42 may instead be on the pressure side 36 of the service brake volume 26. In that case, the pattern 46 may be on the diaphragm 32.
If the sensor 42 transmits sound signals, those signals would then be reflected off of the housing wall 44. Other embodiments in which the sensor 42 is on the pressure side 36 of the service brake volume 26 are also contemplated.
With reference again to
It is also understood that the ECU 22 includes a processor 64 that acts as a means for evaluating the message signals from the sensor electronics 52, which may include interpreting the messages front the sensor electronics 52, comparing the positions of the service volume diaphragms 32 (and plates 33) with, for example, the respective baseline positions or the average of the positions, determining the statuses of the respective service brake volumes 26 based on the evaluations of the signals front the sensor electronics 52 (e.g., based on the comparisons), and transmitting any messages for alerting the operator of the vehicle 10. Therefore, the ECU 22 and/or the ECU processor 64 act as as means for evaluating the signals. The ECU 22 and/or the ECU processor 64 may also act as a means for determining respective positions of diaphragms in service air brake volumes of the brake chambers and for determining the respective statuses of the service brake chambers 26 based on the evaluations of the signals.
While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.
