JP2018184095A - Abnormality determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for determining an abnormal state in which a brake lining is worn without generating a wear warning sound. SOLUTION: In S110, a brake temperature, a vehicle speed, an on / off of a brake signal, and a braking time of each tire are acquired. In S120, the change ΔTn of the brake temperature per unit time is calculated for each tire. In S130, it is determined whether or not the brake is being braked. If the brake is braking, the change upper limit value TH is set in S140 using the control table based on the vehicle speed and the braking time. In S150, it is determined whether or not ΔTn> TH for each tire. If ΔTn> TH for any one of the tires, it is assumed that the brake lining 53 is in an abnormal state of being worn beyond the permissible amount, and the process proceeds to S160. In S160, the detection of the abnormal state is notified via the warning device 4 and the display device 34. [Selection diagram] FIG. 5

Description

  The present disclosure relates to a technique for detecting lining wear in a drum brake.

  Patent Document 1 discloses a technique for notifying a driver of wear of a brake lining in a drum brake used in a large vehicle such as a truck, a bus, or a trailer, and forms a convex portion on a mounting surface of the brake lining in a brake shoe. It is disclosed. In other words, when the brake lining wears beyond the allowable amount, the convex portion comes into contact with the brake drum and a wear warning sound is generated, so that it is possible to notify the driver of the brake lining replacement time by this wear warning sound.

Japanese Utility Model Publication No. 05-025041

  However, as a result of detailed examination by the inventors, for a large vehicle such as a trailer, the driver and the brake may be far away from each other, so that the driver may not notice even if a wear warning sound is generated. Was found. The inventor has also found a problem that bringing the convex portion into contact with the brake drum leads to damage to the brake drum.

  It is an object of the present disclosure to provide a technique for determining an abnormal state in which a brake lining is worn without generating a wear warning sound.

The abnormality determination device of the present disclosure includes a temperature detection unit (2), a determination unit (33), and a notification unit (4, 34).
A temperature detection part detects the temperature of the drum brake (5) which produces a braking force by pressing a brake lining (53) against the brake drum (51) interlock | cooperated with an axle shaft. The determination unit determines whether or not a change per unit time of a brake temperature, which is a temperature detected by the temperature detection unit when the drum brake is operated, exceeds a preset change upper limit value. An alerting | reporting part alert | reports generation | occurrence | production of abnormality, when the determination part judges that the change per unit time of brake temperature exceeds the change upper limit. The change upper limit value is an upper limit value of change per unit time of the brake temperature that can be detected by the temperature detection unit when the wear of the brake lining is within a preset allowable amount.

  According to such a configuration, it is possible to make the driver recognize an abnormal state in which the brake lining is worn without generating a wear warning sound from the brake drum, that is, without damaging the drum brake. In addition, since it is not necessary to check the brake lining condition by directly observing the brake lining, even if wear of the brake lining occurs during long-distance driving or traveling on a long downhill, an abnormal condition can be detected in real time. Can detect and alert the driver. As a result, it is possible to inform the driver of the lining replacement time, which has been difficult for the driver to know.

  Note that the reference numerals in parentheses described in this column and in the claims indicate the correspondence with the specific means described in the embodiment described later as one aspect, and the technical scope of the present disclosure It is not limited.

It is a block diagram which shows the whole structure of an abnormality determination system, and arrangement | positioning of each part which comprises a system. It is explanatory drawing which shows the structure of a drum brake. It is explanatory drawing which shows the attachment position of a temperature detection part. It is a block diagram which shows the structure of a determination apparatus. It is a flowchart of an abnormality determination process. It is explanatory drawing which illustrates the content of the change upper limit table.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[1. overall structure]
The abnormality determination apparatus 1 can be mounted on a vehicle such as a truck or a bus or a towed vehicle such as a trailer to be pulled by the vehicle. The abnormality determination device 1 determines abnormality of drum brakes provided at both ends of each axle of the vehicle. Here, it is determined at least whether or not the lining is in an abnormal state in which the lining is worn beyond an allowable amount as an abnormality of the drum brake. Hereinafter, an example in which the abnormality determination device 1 is applied to a trailer will be described.

  As shown in FIG. 1, the trailer 10 is connected to the rear of the tractor head 11 and pulled. The trailer 10 has three axles with tires attached to both ends. In addition, drum brakes 5 are provided at both ends of each axle.

[1-1. Drum brake]
As shown in FIG. 2, the drum brake 5 includes a brake drum 51, a brake shoe 52, a brake lining 53, an S cam 54, and a return spring 55.

The brake drum 51 is a cylindrical member with a bottom surface removed. The drum is connected to the axle and is configured to rotate with the tire.
The brake shoe 52 is a member having a portion formed in an arc shape. Two brake shoes 52 are provided in one drum brake 5. The pair of brake shoes 52 are arranged at positions where arc-shaped portions face the inner peripheral wall of the drum with a certain gap therebetween, and one ends of the pair of brake shoes 52 are pivotally supported by anchor pins. Hereinafter, in the brake shoe 52, the end opposite to the end pivotally supported by the anchor pin is referred to as an open end.

  The brake lining 53 is attached to a portion of the brake shoe 52 formed in an arc shape, that is, a surface of the brake shoe 52 facing the brake drum 51. The brake lining 53 generates a braking force by being pressed against the inner peripheral wall of the brake drum 51 by the brake shoe 52. Two brake linings 53 are attached to each brake shoe 52. Here, the two brake linings 53 attached to the same brake shoe 52 are separated from each other by several mm to several tens of mm so that a part where the brake shoe 52 is exposed (hereinafter, exposed part 521) is formed between them. Arranged.

  The S cam 54 is an S-shaped member that is rotatably attached to contact the open ends of the pair of brake shoes 52. When the brake pedal is depressed, the actuator 541 rotates the S cam 54 in a direction that widens the open ends of the pair of brake shoes 52, that is, a direction that presses the brake lining 53 against the brake drum 51. As a result, braking is performed by the frictional force generated between the brake lining 53 and the brake drum 51.

  The return spring 55 is connected between the open ends of the pair of brake shoes 52. When the depression of the brake pedal is released, the actuator 541 rotates the S cam 54 in a direction to narrow the gap between the open ends of the pair of brake shoes 52. As a result, the brake lining 53 is held at a position spaced from the brake drum 51 by the urging force of the return spring 55, so that braking is released. Although an example using the S cam 54 is shown here, the S cam 54 and the trailer are often used, and in the truck, a witch is often used instead of the S cam 54.

[1-2. Abnormality judgment device]
Returning to FIG. 1, the trailer 10 includes a plurality of temperature detection units 2, a determination unit 3, a warning device 4, and an in-vehicle device group 6, and these constitute the abnormality determination device 1.

  The temperature detector 2 is provided in each of the plurality of drum brakes 5 included in the trailer 10. As shown in FIG. 3, the temperature detector 2 is disposed between the brake drum 51 and the brake shoe 52. Here, the temperature detection unit 2 is attached to the exposed portion 521 of the brake shoe 52 and detects the temperature of the drum brake 5 by detecting the temperature of the brake shoe 52. The temperature detector 2 is attached to one of a pair of brake shoes 52 included in one drum brake 5. However, it may be attached to both of the pair of brake shoes 52. The temperature detector 2 is a well-known temperature sensor including a thermocouple whose resistance value changes depending on the ambient temperature.

  The temperature detector 2 is formed thinner than the brake lining 53. That is, when the brake lining 53 is not worn, it does not come into contact with the brake drum 51. However, when the thickness of the brake lining 53 becomes less than or equal to the thickness of the temperature detection unit 2 due to wear, the brake lining 53 comes into contact with the brake drum 51. As a result, the temperature detection unit 2 may be destroyed. The upper limit value of the wear amount of the brake lining 53 that does not destroy the temperature detection unit 2 is hereinafter referred to as an allowable wear amount.

  Returning to FIG. 1, the warning device 4 is installed at the front end of the trailer 10, that is, in the vicinity of the boundary with the tractor head 11, at a position where a driver on the tractor head 11 can see through the side mirror. ing.

  The in-vehicle device group 6 is a device that detects or transmits a signal representing the behavior of the vehicle (hereinafter, a behavior signal). The behavior signal provided by the in-vehicle device group 6 includes at least a brake signal and a vehicle speed. The vehicle speed may be obtained using information obtained from a GPS receiver or an acceleration sensor mounted on the vehicle, in addition to obtaining the vehicle speed using information obtained from a vehicle speed sensor provided on the tire of the tractor head 11. GPS is an abbreviation for global positioning system.

  The determination unit 3 is installed in a control box installed at a place where the trailer 10 is easily operated. As shown in FIG. 4, the determination unit 3 includes a plurality of AD conversion units 31, an information acquisition unit 32, a calculation unit 33, and a display device 34.

  The plurality of AD conversion units 31 are provided in association with each of the plurality of temperature detection units 2. The AD conversion unit 31 converts the detection signal from the associated temperature detection unit 2 into digital data and supplies the digital data to the calculation unit 33.

The information acquisition unit 32 acquires a brake signal and a vehicle speed from the in-vehicle device group 6 and supplies them to the calculation unit 33.
The display device 34 includes a liquid crystal panel, and is configured to display the result of determining the abnormality of each tire together with the portion where the abnormality has occurred.

  The arithmetic unit 33 is configured around a known microcomputer having a CPU 331 and a semiconductor memory (hereinafter, memory 332) such as a RAM, a ROM, and a flash memory. Various functions of the calculation unit 33 are realized by the CPU 331 executing a program stored in a non-transitional tangible recording medium. In this example, the memory 332 corresponds to a non-transitional tangible recording medium that stores a program. Also, by executing this program, a method corresponding to the program is executed. Note that the number of microcomputers constituting the calculation unit 33 may be one or more.

  The calculation unit 33 determines a brake abnormality according to information obtained from the plurality of AD conversion units 31 and the information acquisition unit 32 when the CPU 331 executes the program, and the determination result is transmitted via the warning device 4 or the display device 34. At least an abnormality determination process to be notified is executed. The method of realizing the function of the calculation unit 33 is not limited to software, and some or all of the elements may be realized using one or a plurality of hardware. For example, when the above function is realized by an electronic circuit that is hardware, the electronic circuit may be realized by a digital circuit including a large number of logic circuits, an analog circuit, or a combination thereof.

[2. processing]
Next, the abnormality determination process executed by the calculation unit 33 will be described with reference to the flowchart of FIG. This process is periodically executed at a preset interval C (for example, 100 ms). The period in which this process is executed is called a process cycle.

  When this process is activated, the calculation unit 33 acquires various types of information via the plurality of AD conversion units 31 and the information acquisition unit 32 in S110. The information to be acquired includes the brake temperature of each tire, the vehicle speed, the on / off state of the brake signal, and the duration time (hereinafter, the braking time) when the brake signal is on.

In S120, for every tire, it calculates a change [Delta] T _n of the brake temperature. Specifically, _assuming that the brake temperature acquired in the current processing cycle is T _n , and the brake temperature acquired in the previous processing cycle is T _n−1 , the change in brake temperature ΔT _n is obtained by Equation (1). n is a parameter for identifying a processing cycle.

ΔT _n = (T _n −T _n−1 ) (1)
That is, ΔT _n represents the change in the brake temperature per unit time, that is, the rate of change in the brake temperature or the slope of the graph representing the change in the brake temperature, with the processing cycle interval C as the unit time. Note that the frictional heat generated by the friction between the brake lining 53 and the brake drum 51 is more easily transmitted to the brake shoe 52 and thus the temperature detection unit 2 as the brake lining 53 is thinner. Therefore, the change [Delta] T _n of brake temperature, wear of the brake lining 53 becomes a large value according to progress.

  In S130, it is determined whether or not the brake is being braked. Whether or not the brake is being braked is determined according to the brake signal acquired in S110. If the brake signal is on, it is determined that the brake is being applied, and the process proceeds to S140. If the brake signal is off, it is determined that the brake is not being applied and the process proceeds to S150.

  In S140, a change upper limit value TH is set. The change upper limit value TH is an upper limit value of a change in brake temperature that can be regarded as normal. The change upper limit value TH is set using a control table stored in the memory 332 based on the vehicle speed and braking time acquired in S110. As shown in FIG. 6, the control table associates a change upper limit value TH with each braking pattern defined by a combination of the vehicle speed at the start of braking and the braking time. The braking pattern quantitatively indicates the degree of friction generated between the brake lining 53 and the brake drum 51. The change upper limit value TH is set so as to increase as the degree of friction increases. The degree of friction increases as the vehicle speed increases and the braking time increases. As the control table, a table that is set in advance based on an actual measured value of the change ΔT in the brake temperature when the brake lining 53 is in a new state or when the brake lining 53 is worn to an allowable amount is used.

In S150, for every tire, a change [Delta] T _n of the brake temperature obtained in S120, it is determined whether the change is greater than the upper limit value TH set in S140. If any one of the tires is determined to satisfy ΔTn> TH, the process proceeds to S160 because the brake lining 53 is in an abnormal state in which it has worn beyond the allowable amount. When all the tires are reversed as ΔTn ≦ TH, it is determined that the wear of the brake lining 53 is in a normal state within an allowable range, and this processing is terminated.

  In S160, a notification process for notifying that an abnormal state has been detected is performed via the warning device 4 and the display device 34, and this process ends. Specifically, the warning device 4 is activated, and the display device 34 displays the part where the abnormality is detected and the content of the abnormality. The display states of the warning device 4 and the display device 34 set by these notification processes are held until a reset switch (not shown) provided in the determination unit 3 is operated.

[3. effect]
According to the embodiment described in detail above, the following effects can be obtained.
(3a) The abnormality determination device 1 detects a change ΔT in brake temperature per unit time due to brake braking, and the wear of the brake lining 53 is caused when the temperature rises significantly faster than the change upper limit value TH. It is determined that the abnormal state exceeds the allowable amount. In addition, when it is determined that the state is abnormal, the warning device 4 notifies the user and displays the position where the abnormality has occurred on the display device 34.

  Therefore, according to the abnormality determination device 1, the driver can recognize an abnormal state in which the brake lining 53 is worn without generating a wear warning sound from the brake drum 51, that is, without damaging the drum brake 5. .

  (3b) In the abnormality determination device 1, it is not necessary to directly check the state of the brake lining 53 by visually observing the brake lining 53, and the warning device 4 is disposed at a position where it can be visually recognized through the side mirror. Yes. For this reason, even when brake lining wear occurs during long-distance driving or traveling on a long downhill, an abnormal state can be detected in real time and a warning can be given to the driver. As a result, it is possible to inform the driver of the lining replacement time, which has been difficult for the driver to know.

  (3c) In the abnormality determination device 1, not only the warning device 4 but also information related to the content of the abnormal state is displayed on the display device 34. Therefore, by checking the display device 34, the details of the abnormal state can be easily grasped, so that maintainability can be improved. For example, a large vehicle has a large number of shafts (and thus a large number of tires) and a large number of brakes. By checking the display device 34, it is possible to quickly identify which brake has failed.

  (3d) In the abnormality determination device 1, the change upper limit value TH is variably set according to the braking pattern specified from the behavior information, so that the abnormal state can be detected with high accuracy regardless of the behavior of the vehicle.

  (3e) In the abnormality determination apparatus 1, the display device displays the abnormality detection site and the content of the abnormality, so that the location requiring maintenance and the content of the maintenance can be easily identified, and the maintainability is improved. Can be improved.

[4. Other Embodiments]
As mentioned above, although embodiment of this indication was described, this indication is not limited to the above-mentioned embodiment, and can carry out various modifications.

  (3a) In the above embodiment, the temperature detector 2 is attached to the exposed portion 521 of the brake shoe 52, but the present invention is not limited to this. For example, the temperature detection unit 2 may be embedded in the brake lining 53. Further, the temperature detection unit 2 may be provided on the brake drum 51 side. However, in this case, it is necessary to transmit and receive the brake temperature wirelessly. For example, an existing TPMS device may be used. TPMS is an abbreviation for Tire Pressure Monitoring System, that is, Tire Pressure Monitoring System.

  (3b) In the above embodiment, the temperature detection unit 2 is arranged so as to be in contact with a part of the drum brake 5 and detects the temperature of the drum brake 5 itself that generates heat due to friction. However, the present invention is not limited to this. is not. For example, the temperature of the part where the temperature change is detected under the influence of the drum brake 5 that generates heat, that is, the ambient temperature of the drum brake 5 may be detected.

(3c) In the above embodiment, a temperature sensor including a thermocouple is used as the temperature detection unit 2 and ΔT _n is obtained from the temperature difference of the brake temperature in the processing cycle. However, the present invention is not limited to this. For example, a pair of thermostats having different operating temperatures may be used as the temperature detection unit 2, and ΔT _n may be obtained from the operating temperature of the pair of thermostats and the difference in operating timing.

  (3d) In the above embodiment, a preset table is used as the control table used for setting the change upper limit value TH. However, the present invention is not limited to this. For example, after the brake lining 53 is attached or replaced, the control table may be configured to be updated for each braking pattern based on the brake temperature measured during a predetermined period.

  (3e) In the embodiment described above, the determination unit 3 detects the abnormal state of the brake lining 53 based on the brake temperature detected by the temperature detection unit 2, but is not limited to this. In addition to the abnormal state of the brake lining 53, for example, a brake drag may be detected. That is, the temperature detector 2 may be shared with an existing device that detects brake dragging.

  (3f) In the above embodiment, the abnormality notification is performed using the warning device 4 or the display device 34, but is not limited to this. For example, an abnormality notification may be performed audibly using a speaker or the like. Moreover, you may comprise so that information required for a warning, repair, etc. may be notified using a smart phone etc.

  (3g) A plurality of functions of one constituent element in the above embodiment may be realized by a plurality of constituent elements, or a single function of one constituent element may be realized by a plurality of constituent elements. . Further, a plurality of functions possessed by a plurality of constituent elements may be realized by one constituent element, or one function realized by a plurality of constituent elements may be realized by one constituent element. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

  (3h) In addition to the above-described abnormality determination device 1, a system including the abnormality determination device 1 as a component, a program for causing a computer to function as the abnormality determination device 1, a non-transitive semiconductor memory or the like in which the program is recorded The present disclosure can also be realized in various forms such as an actual recording medium and a brake lining wear determination method.

  DESCRIPTION OF SYMBOLS 1 ... Abnormality determination apparatus, 2 ... Temperature detection part, 3 ... Determination part, 4 ... Warning apparatus, 5 ... Drum brake, 6 ... Vehicle equipment group, 10 ... Trailer, 11 ... Tractor head, 31 ... AD conversion part, 32 ... Information acquisition unit 33 ... calculation unit 34 ... display device 51 ... brake drum 52 ... brake shoe 53 ... brake lining 54 ... S cam 55 ... return spring 331 ... CPU 332 ... memory 521 ... exposure Site, 541 ... actuator.

Claims (5)

A temperature detector (2) configured to detect a temperature of a drum brake (5) that generates a braking force by pressing a brake lining (53) against a brake drum (51) interlocked with an axle;
It is configured to determine whether a change per unit time of a brake temperature, which is a temperature detected by the temperature detection unit when the drum brake is operated, exceeds a preset change upper limit value. The determined determination unit (33),
A notification unit (4, 34) configured to notify the occurrence of an abnormality when the determination unit determines that the change per unit time of the brake temperature exceeds the change upper limit value;
With
The change upper limit value is an upper limit value of change per unit time of the brake temperature that can be detected by the temperature detection unit when wear of the brake lining is within a preset allowable amount.
Abnormality judgment device. The abnormality determination device according to claim 1,
An information acquisition unit (32) for acquiring behavior information including at least one of the vehicle speed and the braking time;
The abnormality determination device, wherein the change upper limit value is configured to be set for each braking pattern defined using the behavior information. The abnormality determination device according to claim 1 or 2, wherein
The wear detection device is configured to set the change upper limit value by measuring the brake temperature for a predetermined period after the brake lining is attached or replaced. The abnormality determination device according to any one of claims 1 to 3, wherein:
The temperature detection unit is an abnormality determination device configured to be shared with a device that detects brake drag from the brake temperature. The abnormality determination device according to any one of claims 1 to 4, wherein:
The temperature detection unit is an abnormality determination device arranged between a brake shoe (52) to which the brake lining is attached and the brake drum.