JP2018184094A - Abnormality detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality detection device capable of early and accurately detecting an abnormal state of a brake regardless of an operating state of a vehicle.SOLUTION: An abnormality detection device includes: a temperature detection section for detecting a brake temperature of each of a plurality of drum brakes; a trajectory length calculation section for calculating a trajectory length that is a length of a trajectory indicating fluctuation of each detected brake temperature in a preset calculation period; an abnormality determination section for comparing the calculated trajectory lengths with each other and when a trajectory length longer than the other trajectory lengths and exceeding a preset length deviation threshold value is present, determining that the drum brake corresponding the trajectory length is abnormal; and a notification section configured to inform occurrence of an abnormality when the abnormality of the drum brake is determined.SELECTED DRAWING: Figure 7

Description

  The present disclosure relates to a technique for detecting a vehicle brake abnormality.

  Patent Document 1 discloses a temperature state detection device that detects an abnormal temperature state in a drum brake used in a trailer that is pulled by a tractor and notifies a driver. When the drum brake temperature exceeds the temperature threshold in a predetermined temperature change state and exceeds the temperature threshold for a predetermined time, the device determines that it is abnormal and notifies the driver Prompts.

JP 2004-197894 A

  The above apparatus uses that the temperature of the drum brake exceeds the temperature threshold in a predetermined temperature change state as the determination condition for the abnormal state, but the temperature change varies depending on the actual running state. For example, the temperature change when traveling at a low speed and the temperature change when traveling at a high speed are greatly different. Therefore, the above-described device has a problem that although the temperature state of the brake is an abnormal state, the abnormal state cannot be detected or the abnormal state is erroneously detected although it is not an abnormal state.

  This indication is made in view of the above-mentioned situation, and makes it a main object to provide the abnormality detection device which can detect the abnormal state of a brake early and accurately irrespective of the operation state of vehicles. .

  The present disclosure is an abnormality detection device, and includes a temperature detection unit (2), a trajectory length calculation unit (3), an abnormality determination unit (3), and a notification unit (34, 4). A temperature detection part each detects the brake temperature which is the temperature of the several drum brake (5) provided in the axle shaft of the vehicle (10). The trajectory length calculation unit calculates a trajectory length that is the length of the trajectory representing the variation of each brake temperature detected by the temperature detection unit in a preset calculation period. The abnormality determination unit compares the plurality of trajectory lengths calculated by the trajectory length calculation unit with each other, and when there is a trajectory length that is longer than a predetermined length deviation threshold than other trajectory lengths, It is determined that the drum brake corresponding to the trajectory length is abnormal. The notifying unit notifies the occurrence of an abnormality when the abnormality determining unit determines that the drum brake is abnormal.

  According to the present disclosure, the trajectory lengths of the brake temperatures of a plurality of brakes are calculated, and the calculated trajectory lengths are compared with each other. Here, when the brake is dragged, the temperature change tends to increase and the trajectory length tends to increase. Therefore, the brake abnormal state can be detected using the brake track length. Further, even when the brake temperature is lowered by water drops such as wind and rain during traveling, the trajectory length is increased by the amount of temperature change. Therefore, the brake abnormality can be detected at an early stage by detecting the brake abnormal state from the trajectory length.

Furthermore, even when the drag degree is weak and the change in the brake temperature is small, it becomes longer than the trajectory length of the brake where no drag is generated. Therefore, by comparing the trajectory lengths of a plurality of brakes, it is possible to detect a brake abnormality even when the dragging degree is weak. Therefore, regardless of the operation status of the vehicle, it is possible to detect an abnormality of the brake early and accurately and warn the driver.

  In addition, the code | symbol in the parenthesis described in this column and a claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is shown. It is not limited.

It is a block diagram which shows arrangement | positioning of each part which comprises the whole structure and abnormality detection apparatus of a vehicle by which an abnormality detection apparatus is mounted. It is explanatory drawing which shows the structure of a drum brake. It is a block diagram which shows the structure of an abnormality detection apparatus. It is a figure which shows the determination part installed in the control box. It is a figure which shows the temperature change of the brake of a normal state and an abnormal state. It is a figure which shows the temperature change of the brake of a normal state and an abnormal state. It is a flowchart of an abnormality detection process. It is a figure explaining the setting of the threshold value according to a braking state. It is a flowchart of the process which changes a gradient threshold value according to the ratio of brake ON. It is a flowchart of the process which changes a length deviation threshold value according to the frequency of a brake.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.
[1. overall structure]
First, the overall configuration of a vehicle equipped with the abnormality detection device 1 according to the present embodiment will be described with reference to FIG. The abnormality detection device 1 can be mounted on a towed vehicle such as a truck or a bus or a trailer to be pulled by the car. The abnormality detection device 1 detects an abnormality of drum brakes provided at both ends of each axle of the vehicle. Here, it is determined at least whether or not the drum brake is in an abnormal state where the drum brake is dragged. Hereinafter, an example in which the abnormality detection device 1 is mounted on the trailer 10 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 brake drum 51 is connected to the axle and is configured to rotate with the tire.
The brake shoe 52 is a pair of members having a portion formed in an arc shape. 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.

Two brake linings 53 are attached to the surface of each 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. The two brake linings 53 are
They are arranged to talk about several mm to several tens of mm so that an exposed portion 521 where the brake shoe 52 is exposed is formed between them.

  The S cam 54 is an S-shaped member that is rotatably attached to contact one end of each 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 end portions 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 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 ends of the pair of brake shoes 52. As a result, the biasing force of the return spring 55 creates a gap between the brake lining 53 and the brake drum 51, and braking is released. Here, an example in which the S cam 54 is used has been described, but the S cam 54 is often used in a trailer, and a witch is often used instead of the S cam 54 in a truck.

  Here, the brake dragging is a state in which the brake lining 53 remains pressed against the brake drum 51 due to a failure of the brake system of the trailer 10 and braking force is continuously generated in the drum brake 5. When such brake dragging occurs, the temperature of the drum brake 5 rises, and there is a possibility that oils and fats such as grease in the drum brake 5 may ignite, or a tire may burst or fire. In general, when the brake system of the trailer 10 fails, fail-safe control is performed in a direction in which a braking force is generated in the drum brake 5. Hereinafter, a state where the braking force is generated in the drum brake 5 is referred to as ON of the drum brake 5, and a state where the braking force is not generated in the drum brake 5 is referred to as OFF of the drum brake 5.

[1-2. Anomaly detection device]
Next, returning to FIG. 1, the configuration of the abnormality detection device 1 will be described. The abnormality detection device 1 includes a plurality of temperature detection units 2, a determination unit 3, a warning device 4, and an in-vehicle device group 6.

  The temperature detection unit 2 is a known temperature sensor including a contact-type temperature detection element. An example of the contact-type temperature sensor is a thermistor whose resistance value varies depending on the ambient temperature. The temperature detection unit 2 is provided in each of the plurality of drum brakes 5 included in the trailer 10, and detects the drum brake 5 or the temperature around the drum brake 5 as the brake temperature.

  Specifically, as shown in FIG. 2, the temperature detection unit 2 is attached to the exposed portion 521 of the brake shoe 52 and detects the temperature of the brake shoe 52 as the brake temperature. 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 may be attached to the brake lining 53 and may detect the temperature of the brake lining 53 as a brake temperature, or may be attached to the periphery of the brake drum 51 to detect the ambient temperature as a brake temperature. Also good.

  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 riding on the tractor head 11 can visually recognize through the side mirror.

  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 is obtained by using the GPS reception signal received by the GPS receiver mounted on the vehicle or the acceleration detected by the acceleration sensor, in addition to obtaining the vehicle speed using information obtained from the vehicle speed sensor provided on the tire of the tractor head 11. You may make it obtain | require using. GPS is an abbreviation for global positioning system.

  As illustrated in FIG. 3, the determination unit 3 is a control board including a plurality of AD conversion units 31, an information acquisition unit 32, a calculation unit 33, and a display device 34. The determination unit 3 is connected to the plurality of temperature detection units 2, the in-vehicle device group 6, and the warning device 4 through wires 7, and exchanges signals through the wires 7.

  As shown in FIG. 4, the determination unit 3 is housed in the control box 8 and installed in a place where the trailer 10 is easy to work. The control box 8 includes a rectangular main body 81 having an open front surface and an opening / closing door 82, and the determination unit 3 is installed on the rear surface of the main body 81 with the display device 34 facing forward. The open / close door 82 is provided with a transparent viewing window 83 so that the display device 34 can be viewed from the viewing window 83. Further, the wire 7 connected to the determination unit 3 is taken out from a through hole provided in the bottom surface of the main body unit 81. A foamed rubber material 84 is disposed in the gap between the main body 81 and the open / close door 82 and the gap between the through hole and the wire 7 to provide a waterproof treatment.

  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 signal 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 detecting the abnormality of each drum brake 5 together with the portion where the abnormality has occurred, that is, which drum brake 5 is abnormal. In the present embodiment, the display device 34 and the warning device 4 correspond to a notification unit.

  The calculation unit 33 is configured around a known microcomputer having a CPU 331 and a memory 332 which is a semiconductor memory 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 embodiment, the memory 332 corresponds to a non-transitional tangible recording medium storing a program, and various functions of the calculation unit 33 are a gradient calculation unit, a trajectory length calculation unit, an abnormality determination unit, a threshold setting unit, a period It is a setting part. The threshold setting unit includes a length deviation threshold setting unit and a trajectory length threshold setting unit. 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 detection process to be notified is executed. The method for 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]
[2-1. Anomaly detection processing]
First, parameters used for detecting brake abnormality will be described with reference to FIGS. FIGS. 5 and 6 show brake temperature change patterns A to I when the travel pattern is changed from the stop state to the acceleration period → the constant speed period → the deceleration period → the stop period.

  The change patterns A, E, F, and G are examples when the drum brake 5 is in a normal state. In the change patterns A, E, F, and G, the brake temperature is substantially constant because the drum brake 5 is off during the acceleration period and the constant speed period. In the change patterns A, E, F, and G, the drum brake 5 is turned on during the deceleration period, the brake temperature gradually rises, and the drum brake 5 is turned off during the stop period. The temperature is substantially constant.

On the other hand, the change patterns B, C, D, H, and I are examples when the drum brake 5 is in an abnormal state.
The change patterns C and D are examples in which a failure has occurred during the previous run and heat is stored in the drum brake 5 before the acceleration period. In the change patterns C and D, the temperature threshold is already exceeded at the acceleration period start position P3 and position P4. Therefore, in the change patterns C and D, a brake abnormality is detected at the start of the acceleration period by comparing the current temperature value of the brake temperature with the temperature threshold value.

  Further, the change pattern B is an example in which the brake system of the trailer 10 has failed before the vehicle starts running or after the acceleration period starts. In the change pattern B, the brake temperature gradually increases even in the acceleration period and the constant speed period in which the drum brake 5 is off. However, in the change pattern B, the brake temperature is less than the temperature threshold until the deceleration period. That is, in the change pattern B, even if the current temperature value of the brake temperature is used, the brake abnormality is not detected until the deceleration period is reached.

  Here, in the change pattern B, the temperature gradient of the brake temperature at the position P2 before the deceleration period is larger than the temperature gradient of the change pattern A at the position P1 corresponding to the position P2. Therefore, in the change pattern B, a brake abnormality is detected at an early stage by comparing the temperature gradient of the brake temperature with the gradient threshold value. As for the temperature gradient, the rising gradient is a positive value, and the falling gradient is a negative value.

  Furthermore, in the change pattern B, the brake temperature fluctuates more than when the drum brake 5 is in a normal state. Therefore, in the change pattern B, the trajectory length of the brake temperature from the start of the acceleration period to the position P2 is longer than the trajectory length of the change pattern A from the start of the acceleration period to the position P1. The trajectory length is the length of the trajectory indicating the variation of the brake temperature, that is, the length of the curve of the change pattern B. In other words, the trajectory length is the sum of changes in brake temperature during the trajectory length calculation period. The amount of change in brake temperature is the amount of change in the processing cycle. The trajectory length is increased by the amount of temperature change even when the brake temperature decreases due to water droplets such as wind and rain water when the vehicle is traveling. Therefore, in the change pattern B, a brake abnormality is detected at an early stage by comparing the locus length of the brake temperature with the locus length threshold.

Furthermore, the change pattern H is an example in which the brake system of the trailer 10 has failed before the start of traveling of the vehicle or after the start of the acceleration period, and dragging is weaker than the change pattern B. The change pattern I is stored in the drum brake 5 before the acceleration period, but the amount of stored heat is smaller than that of the change patterns C and D, and the drag is weaker than that of the change pattern B. It is. As shown in the change patterns H and I, when the drag is weak, the brake temperature rises moderately. Therefore, similarly to the change patterns B to D, even when the change patterns are viewed individually, the detection of the brake abnormality is slow. Or may not be detected. Here, in the change pattern H, the temperature gradient and the trajectory length deviate from the temperature gradient and the trajectory length of the change patterns E, F, and G at the position P6 as compared with other normal change patterns E, F, and G. ing. Further, in the change pattern I, the temperature gradient deviates from the temperature gradients of the change patterns E, F, and G at the position P5 as compared with other normal change patterns E, F, and G. Therefore, in the change patterns H and I with weak dragging, it is preferable to compare the temperature gradients and locus lengths of the brake temperatures of the plurality of drum brakes 5 with each other. Then, by comparing the deviation amount of the temperature gradient with the other brake temperature and the gradient deviation threshold value, or comparing the deviation amount of the trajectory length with the other brake temperature and the length deviation threshold value, it is possible to brake quickly. An abnormality is detected.

  In addition, the change patterns H and I of the weak drag example are more similar to the change patterns of the brake temperature when a severe brake operation is performed, as compared with the change patterns B to D, the increase in the brake temperature is moderate. Change pattern. Therefore, when there is a change pattern in which the brake temperature gradually increases, such as change patterns H and I, it is determined whether the brake temperature has increased due to weak dragging or the brake temperature has increased due to severe braking operation. There is a need to. Here, an increase in brake temperature during a weak drag state appears even when the drum brake 5 is off, whereas an increase in brake temperature during a severe brake operation does not appear when the drum brake 5 is off. That is, when the drum brake 5 is off, or when the braking period in the calculation period for calculating the trajectory length is small (hereinafter referred to as the ON ratio), if the brake temperature rises, it can be determined that the dragging state is present.

  As described above, in this embodiment, the temperature gradient of the brake temperature in the predetermined calculation period, the deviation amount of the temperature gradient, the trajectory length of the brake temperature in the calculation period, the deviation amount of the trajectory length, the brake temperature, and the brake off signal or ON Using the ratio, the brake abnormality is determined.

  Next, the processing procedure of the abnormality detection process will be described with reference to the flowchart of FIG. This processing procedure is periodically executed at intervals set in advance by the calculation unit 33. In the present embodiment, the computing unit 33 executes this processing procedure at 1s intervals. Note that the period in which this processing procedure is executed is referred to as a processing cycle.

  First, in step S <b> 10, various types of information are acquired via the plurality of AD conversion units 31 and the information acquisition unit 32. 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 continuation period (hereinafter referred to as the braking period) when the brake signal is on. The braking period here is a braking period due to brake friction, is a period in which the drum brake 5 is on and the vehicle speed is decelerating, and a period in which the drum brake 5 is on and the vehicle is stopped. Is not included.

  Subsequently, in step S20, various parameters used for abnormality determination are calculated. Specifically, the calculation period of various parameters, the temperature gradient of the brake temperature between processing cycles, the deviation from the temperature gradient of other brake temperatures, the trajectory length during the calculation period, the deviation from the trajectory length of other brake temperatures Is calculated. At that time, the value of the brake temperature detected by the temperature detector 2 in the latest N processing cycles is moving averaged, and the value obtained by moving average is used as the brake temperature. N is a natural number, for example, 10. The calculation period is changed according to the vehicle speed. Specifically, the calculation period is shortened as the vehicle speed increases. For example, the calculation period is 10 s at 50 km / h. The temperature gradient calculation period and the trajectory length calculation period may be different periods. Note that the period of the last N processing cycles corresponds to the average period.

Furthermore, the vehicle braking state and various threshold values are calculated as various parameters. The braking state of the vehicle is the ratio of the braking period in the calculation period and the number of times the drum brake 5 is switched from on to off in the calculation period. The various threshold values are a gradient threshold value, a temperature threshold value, a gradient deviation threshold value, a trajectory length threshold value, and a length deviation threshold value. Details of the calculation of various threshold values will be described later.

  Subsequently, in step S30, for each drum brake 5, the parameter calculated in step S20 is compared with a threshold value to determine whether or not each drum brake 5 is abnormal. Specifically, in consideration of the OFF signal or ON ratio of the drum brake 5, (1) the temperature gradient is larger than the gradient threshold, (2) the current temperature value is larger than the temperature, or (3) the temperature It is determined whether the gradient divergence amount is larger than the gradient divergence threshold value, (4) the trajectory length is larger than the trajectory length threshold value, or (5) the trajectory length divergence amount is larger than the length deviation threshold value. If none of the drum brakes 5 satisfies the conditions (1) to (5), it is determined that any drum brake 5 is normal, and the process is terminated.

  On the other hand, if any one of the drum brakes 5 satisfies the conditions (1) to (5), the process proceeds to step S40 to notify that a brake abnormality has been detected. At this time, in order to suppress erroneous notification, notification may be made on condition that a brake abnormality is detected continuously in two processing cycles. 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, that is, which condition (1) to (5) is satisfied. Thereby, since the location which needs a maintenance is alert | reported, maintainability improves. Further, the part where the abnormality is detected and the content of the abnormality are stored in the memory 332. Information stored in the memory 332 can be used for failure analysis at a later date. This process is complete | finished above.

  In the present embodiment, the process in step S20 corresponds to a process executed by realizing the functions of the gradient calculation unit, the trajectory length calculation unit, the threshold setting unit, and the period setting unit. Further, the process of step 30 corresponds to a process executed by realizing the function of the abnormality determination unit.

[2-2. Threshold setting process]
Next, setting of various threshold values will be described. When a severe braking operation is performed, the temperature gradient tends to increase and the trajectory length tends to increase as the ON ratio increases, even if the brake is not dragged. Further, when the drum brake 5 is switched from on to off, a constant change occurs after the brake temperature once rises, so that the trajectory length may be longer than when dragging occurs. That is, the trajectory length tends to increase as the number of times of switching the drum brake 5 from on to off (hereinafter, the number of times of switching) increases as a severe brake operation is performed.

  FIG. 8 shows how the brake temperature rises when the drum brake 5 is weakly dragged. In FIG. 8, the drum brake 5 remains off for 5 minutes indicating a temperature change, and the temperature gradually rises, and the temperature gradient at 1 minute and 5 minutes is 0.167 ° C./s. ing. Here, if the gradient threshold is set to a value smaller than 0.167 ° C./s, in the example shown in FIG. 8, a brake abnormality in a weak drag state is detected. However, if the gradient threshold value is fixed to a value smaller than 0.167 ° C./s, there is a risk that when a severe braking operation is performed, an abnormality is erroneously detected although it is normal. Therefore, when a severe braking operation is not performed, the gradient threshold is set to be relatively small so that a weak drag state can be detected at an early stage. When a severe braking operation is performed, an abnormality is erroneously detected. The gradient threshold value may be set relatively large so as not to detect. The same can be said for other threshold values. Therefore, in the present embodiment, the trajectory length threshold is changed according to the ON ratio and the vehicle speed. In addition, the length deviation threshold is changed according to the number of times of switching in the calculation period.

Next, the procedure of the locus length threshold setting process will be described with reference to the flowchart of FIG.
First, in step S100, the trajectory length threshold is set to BASE, which is a reference value. Subsequently, in step S110, it is determined whether the ratio of the braking period in the calculation period (hereinafter referred to as ON ratio) is 0% or more and less than 10%. When the ON ratio is 0% or more and less than 10%, the process proceeds to step S210. On the other hand, if the ON ratio is 10% or more, the process proceeds to step S120.

  In step S120, it is determined whether the ON ratio is 10% or more and less than 30%. When the ON ratio is 10% or more and less than 30%, the process proceeds to step S130, and the trajectory length threshold is set to a value of BASE × 1.2 times. On the other hand, if the ON ratio is 30% or more, the process proceeds to step S140. In step S140, it is determined whether the ON ratio is 30% or more and less than 50%. When the ON ratio is 30% or more and less than 50%, the process proceeds to step S150, and the trajectory length threshold is set to a value of BASE × 1.4. On the other hand, when the ON ratio is 50% or more, the process proceeds to step S160.

  In step S160, it is determined whether the ON ratio is 50% or more and less than 70%. If the ON ratio is 50% or more and less than 70%, the process proceeds to step S170, and the trajectory length threshold is set to a value of BASE × 1.6. On the other hand, when the ON ratio is 70% or more, the process proceeds to step S180. In step S180, it is determined whether the ON ratio is 70% or more and less than 90%. When the ON ratio is 70% or more and less than 90%, the process proceeds to step S190, and the trajectory length threshold is set to a value of BASE × 1.8 times. On the other hand, when the ON ratio is 90% or more, the process proceeds to step S200. In step S200, the trajectory length threshold is set to a value of BASE × 2.0, and the process proceeds to step S210.

  In step S210, it is determined whether the braking brake is performed at a high speed. Specifically, it is determined whether the vehicle speed is higher than a high speed threshold. The high speed threshold is set to 60 km / h, for example. If the braking brake is not performed at high speed, the already set trajectory length threshold is used as it is as the trajectory length threshold. On the other hand, in the case of braking at high speed, a value obtained by multiplying the already set gradient threshold value by 1.5 is used as the trajectory length threshold value. This process is complete | finished above. A braking period may be used instead of the ON ratio. In this case, the trajectory length threshold may be set to a larger value as the braking period is longer. The gradient threshold value may be set similarly.

Next, the processing procedure of the length divergence threshold setting process will be described with reference to the flowchart of FIG.
First, in step S400, the length deviation threshold is set to BASE, which is a reference value. Subsequently, in step S410, it is determined whether the number of times of switching is less than one. If the number of times of switching is less than one, this processing is terminated as it is. That is, the length deviation threshold set in BASE is used. On the other hand, if the number of times of switching is one or more, the process proceeds to step S420.

  In step S420, it is determined whether the number of times of switching is one or more and less than three. If the number of times of switching is one or more and less than three, the process proceeds to step S430, and the length deviation threshold is set to a value of BASE × 1.2. On the other hand, if the number of times of switching is three or more, the process proceeds to step S440. In step S440, it is determined whether the number of times of switching is 3 times or more and less than 5 times. If the number of times of switching is 3 times or more and less than 5 times, the process proceeds to step S450, and the length deviation threshold is set to a value of BASE × 1.4. On the other hand, if the number of times of switching is 5 or more, the process proceeds to step S460.

In step S460, it is determined whether the number of times of switching is 5 times or more and less than 7 times. When the number of times of switching is 5 times or more and less than 7 times, the process proceeds to step S470, and the length deviation threshold is set to a value of BASE × 1.6. On the other hand, if the number of times of switching is 7 or more, the process proceeds to step S480. In step S480, it is determined whether the number of times of switching is 7 times or more and less than 9 times. When the number of times of switching is 7 times or more and less than 9 times, the process proceeds to step S490, and the length deviation threshold is set to a value of BASE × 1.8 times. On the other hand, if the number of times of switching is 9 or more, the process proceeds to step S500. In step S500, the length deviation threshold is set to a value of BASE × 2.0. This process is complete | finished above.

[3. effect]
According to the first embodiment described above, the following effects can be obtained.
(1) By using the trajectory length of the brake temperature, it is possible to detect an abnormality of the brake early and accurately even when the brake temperature is lowered due to water droplets such as wind or rain during traveling.

(2) By comparing the trajectory lengths of a plurality of brake temperatures with each other, it is possible to detect an abnormality in the brake even when the drag degree is weak and the amount of change in the brake temperature is small.
(3) By comparing each of the trajectory lengths of a plurality of brake temperatures with the trajectory length threshold, it is possible to detect a brake abnormality even when all the drum brakes 5 are in the drag state.

  (4) When a severe brake operation is performed, the deviation amount of the trajectory length tends to increase. Therefore, the length deviation threshold is variably set according to the braking state of the drum brake 5. Thereby, when a severe brake operation is performed, the length deviation threshold value can be increased to prevent erroneous detection of the normal state of the drum brake 5 as an abnormal state. In addition, when a severe braking operation is not performed, the length deviation threshold value can be reduced, and a brake abnormality can be detected at an early stage even in a weak drag state.

  (5) When a severe brake operation is performed, the trajectory length becomes long and the temperature gradient of the brake temperature tends to increase. Further, when the vehicle speed is high, the trajectory length becomes long and the temperature gradient of the brake temperature tends to increase. Therefore, the trajectory length threshold value and the gradient threshold value are variably set according to the braking state of the brake 5 and the vehicle speed. Thereby, when severe braking operation is performed or the vehicle speed is high, it is possible to suppress the erroneous detection of the normal state of the drum brake 5 as an abnormal state by increasing the gradient threshold value. In addition, when a severe braking operation is not performed and the vehicle speed is low, the gradient threshold value can be reduced, and even in a weak drag state, an abnormality in the brake can be detected early.

  (6) Since the brake temperature is smoothed by moving average, the S / N ratio can be increased and the temperature gradient and the trajectory length can be calculated with high accuracy. As a result, it is possible to detect a brake abnormality with high accuracy.

(7) By comparing the temperature gradients of a plurality of brake temperatures, it is possible to detect an abnormality in the brake even when the dragging degree is weak and the temperature gradient of the brake temperature is gentle.
(8) By detecting an abnormality in the brake using the current temperature, it is possible to detect an abnormality in the brake even when all the drum brakes 5 are in the drag state and the drag level is weak.

  (9) When the vehicle is traveling at a high speed, the brake abnormality is likely to be more dangerous than when the vehicle is traveling at a low speed. Therefore, it is necessary to detect the brake abnormality at an early stage. On the other hand, if the calculation period is shortened, there is a possibility that the detection accuracy of the brake abnormality may be lowered. Therefore, by changing the calculation period according to the vehicle speed, it is possible to appropriately balance the early detection of the brake abnormality and the detection accuracy of the brake abnormality.

(10) The braking state of the vehicle can be determined using the low-accuracy vehicle speed calculated from the GPS reception signal or the vehicle speed estimated from the acceleration without using the accurate vehicle speed. Also, compared to vehicle speed sensors, GPS receivers and G sensors can be placed on the board of the anomaly detection system, so instead of using vehicle speed sensors, using GPS receivers and G sensors can reduce the number of mounting steps. Can be reduced.

(11) Since the temperature of the brake shoe or lining which is not a rotating body is detected, the temperature can be easily detected.
(12) Compared with a non-contact type temperature sensor, the contact type temperature sensor is not affected by brake dust, mud, oil, etc., so that the temperature detection is less aged and the circuit is simple. Further, the contact type temperature sensor is cheaper and easier to install than the non-contact type temperature sensor.

[Other Embodiments]
As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the above-mentioned embodiment, It can implement in various deformation | transformation.

  (A) In the above embodiment, each of the various threshold values is set and the warning is performed in one stage. However, the present invention is not limited to this. For example, two threshold values are set for each of the various threshold values: a caution threshold value for calling attention and a warning threshold value for requesting an urgent action with a value larger than the caution threshold value. Then, the notification mode may be changed between the case where the determination value is between the caution threshold and the warning threshold and the case where the determination value exceeds the warning threshold to notify the driver of the danger level.

  (B) In the above embodiment, the abnormal state is reported using the warning device 4 or the display device 34, but the present invention is not limited to this. For example, an abnormal state may be notified audibly using a speaker or the like. Or you may make it send a warning to a driver using communication means, such as a pager and a smart phone.

(C) Although the temperature sensor provided with the contact-type temperature detection element is used as the temperature detection unit 2 in the above embodiment, a temperature sensor provided with a non-contact-type temperature detection measure may be used.
(D) In the above embodiment, the temperature detection unit 2 is attached to the exposed portion 521 of the brake shoe 52, but 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.

  (E) 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 only by the wording described in the claim are embodiment of this invention.

  (F) In addition to the above-described abnormality detection device, a system including the abnormality detection device as a constituent element, a program for causing a computer to function as the abnormality detection device, and a non-transitional actual recording such as a semiconductor memory in which the program is recorded The present invention can also be realized in various forms such as a medium and a brake abnormality detection method.

  DESCRIPTION OF SYMBOLS 1 ... Abnormality detection apparatus, 2 ... Temperature detection part, 3 ... Determination part, 4 ... Warning apparatus, 5 ... Drum brake, 6 ... Vehicle equipment group, 7 ... Wire, 8 ... Control box, 10 ... Trailer, 34 ... Display device .

Claims (7)

A temperature detector (2) for detecting brake temperatures, which are temperatures of a plurality of drum brakes (5) provided on an axle of the vehicle (10), respectively;
A trajectory length calculation unit (3) configured to calculate a trajectory length that is a length of a trajectory representing a variation in each brake temperature detected by the temperature detection unit in a preset calculation period;
A plurality of the locus lengths calculated by the locus length calculation unit are compared with each other, and when the locus length is longer than a predetermined length divergence threshold than the other locus lengths, the locus is present. An abnormality determination unit (3) configured to determine that the drum brake corresponding to the length is abnormal;
A notification unit (34, 4) configured to notify the occurrence of an abnormality when the abnormality determination unit determines that the drum brake is abnormal;
An abnormality detection device comprising:   The abnormality detection device according to claim 1, further comprising a length deviation threshold setting unit (3) configured to change the length deviation threshold according to a braking state of the vehicle in the calculation period.   The abnormality determination unit determines that the drum brake corresponding to the locus length is abnormal when the locus length calculated by the locus length calculation unit is longer than a preset locus length threshold. The abnormality detection device according to claim 1 or 2, wherein the abnormality detection device is configured.   The abnormality detection device according to claim 3, further comprising a trajectory length threshold setting unit (3) configured to change the trajectory length threshold in accordance with a braking state of the vehicle in the calculation period.   The braking state of the vehicle is any one of the number of times the drum brake is switched from on to off in the calculation period, a braking period due to brake friction, and a ratio of the braking time in the calculation period. The abnormality detection device described in 1.   The abnormality detection device according to claim 1, further comprising a period setting unit (3) configured to change the calculation period according to a speed of the vehicle.   The threshold setting unit is configured to estimate the speed of the vehicle from the GPS received signal or acceleration detected by an acceleration sensor, and to determine the braking state of the vehicle using the estimated speed of the vehicle. The abnormality detection device according to claim 2 or 3.

Images