JP7280177B2 - Brake abnormality detection device - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a device for detecting abnormality in vehicle brakes.

The abnormality detection device described in Patent Document 1 calculates the temperature gradient of the brake temperature during a predetermined calculation period, and determines that the drum brake is abnormal when the calculated temperature gradient is greater than a preset gradient threshold. ing. In addition, the device increases the slope threshold value as the ratio of the braking period of the vehicle in the predetermined calculation period increases or as the braking period increases. increase and avoid false positives.

JP 2018-184096 A

By the way, when the slope of the road surface is steep, even if the braking period is small or the braking period is short, the brake temperature may increase as much as the drag of the drum brake. In addition, if the vehicle is stopped with heat accumulated in the brakes after the vehicle has been braked by the drum brakes, the cooling effect of the running wind cannot be obtained, so the brake temperature rises significantly, causing dragging of the drum brakes. A similar gradient of brake temperature rise may occur. Therefore, the above device may erroneously detect that the drum brake is in an abnormal state even if the drum brake is in a normal state, depending on the slope of the road surface and the state of the vehicle.

An object of the present disclosure is to provide a brake abnormality detection device capable of improving detection accuracy of an abnormal state of a drum brake.

One aspect of the present disclosure includes a temperature detection unit (31, S10), a gradient calculation unit (33, S20), a threshold calculation unit (33, S30), and a gradient abnormality determination unit (33, S40). Prepare. The temperature detection unit detects a brake temperature, which is the temperature of a drum brake provided on an axle of the vehicle. The gradient calculator calculates the temperature gradient of the brake temperature detected by the temperature detector in a preset calculation period. The threshold calculation unit calculates a slope threshold according to at least one of the slope of the road on which the vehicle is running and the state of the vehicle. The gradient abnormality determination unit determines that the drum brake is abnormal when the temperature gradient calculated by the gradient calculation unit is larger than the gradient threshold calculated by the threshold calculation unit. Further, the gradient abnormality determination unit stops the abnormality determination of the drum brake using the temperature gradient according to at least one of the inclination of the road surface on which the vehicle is running and the state of the vehicle.

According to the present disclosure, the drum brake abnormality determination using the temperature gradient is stopped according to at least one of the road surface inclination and the vehicle state. That is, when there is a possibility that a brake temperature rise gradient similar to that in the case of drum brake drag occurs, the abnormality determination of the drum brake using the temperature gradient is stopped. Therefore, the possibility of erroneously detecting the normal state of the drum brake as an abnormal state can be eliminated, and the detection accuracy of the abnormal state of the drum brake can be improved.

1 is a block diagram showing the configuration of a brake abnormality detection device according to a first embodiment; FIG. 4 is a flowchart showing abnormality detection processing according to the first embodiment; 6 is a flowchart showing gradient threshold calculation processing according to the first embodiment; It is a flow chart which shows stop judging processing concerning a 1st embodiment. 6 is a flowchart showing downhill determination processing according to the first embodiment; 4 is a flowchart showing brake determination processing according to the first embodiment; 4 is a time chart of brake temperature and vehicle speed during and after running downhill; 4 is a time chart of the temperature gradient of the brake temperature and the brake signal during and after running downhill; 9 is a flowchart showing downhill determination processing according to the second embodiment; FIG. 12 is a flowchart showing downhill determination processing according to the third embodiment; FIG. FIG. 14 is a flowchart showing gradient threshold calculation processing according to the fourth embodiment; FIG. FIG. 14 is a flowchart showing downhill determination processing according to the fourth embodiment; FIG.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this disclosure is demonstrated, referring drawings.
<1. Configuration>
First, the configuration of the brake abnormality detection device 3 according to this embodiment will be described with reference to FIG. The brake abnormality detection device 3 is mounted on an automobile such as a truck or a bus or a towed vehicle such as a trailer towed by the automobile, and detects an abnormality of the drum brake. Tires and drum brakes are provided at both ends of each of a plurality of axles that automobiles and towed vehicles have.

In this embodiment, at least the state in which the drum brake is dragging is detected as the abnormal state of the drum brake. Brake dragging is a condition in which the brake lining of a drum brake remains pressed against the brake drum due to a failure in the brake system, causing the drum brake to continue to generate braking force. When such brake drag occurs, the temperature of the drum brake rises, and oils and fats such as grease in the drum brake may ignite, or the tire may explode or catch fire.

The brake abnormality detection device 3 is connected to the temperature measurement unit 2, the vehicle state estimation unit 6, and the warning device 4 by wires, and transmits and receives signals via the wires.
The temperature measurement unit 2 includes multiple temperature sensors 20 . Each of the plurality of temperature sensors 20 is provided for each of the plurality of drum brakes, and detects the temperature of the drum brake or the temperature around the drum brake as the brake temperature. The temperature sensor 20 has a contact-type temperature detection element. As a contact-type temperature detection element, for example, a thermocouple whose electromotive force changes depending on temperature can be used. Each temperature sensor 20 outputs an analog detection signal of the detected brake temperature to the brake abnormality detection device 3 .

The vehicle state estimator 6 includes various devices that output information for estimating the state of the vehicle. In this embodiment, the vehicle state estimator 6 comprises a brake lamp 61 , a Global Positioning System (GPS) receiver 62 and an acceleration sensor 63 .

The brake lamp 61 is provided at the rear portion of the trailer vehicle, and is energized and turned on when the drum brake is operated. The brake lamp 61 outputs a signal indicating an energized state to the brake abnormality detection device 3 when the brake lamp 61 is energized. The GPS receiver 62 receives GPS signals and outputs the GPS signals to the brake abnormality detection device 3 . The acceleration sensor 63 detects acceleration in three mutually orthogonal axes and outputs the detected acceleration signals to the brake abnormality detection device 3 .

The brake abnormality detection device 3 includes an AD conversion section 31 , a vehicle information acquisition section 32 , a calculation section 33 and a display device 34 .
The AD converter 31 detects the brake temperature by converting the analog detection signal output from each of the plurality of temperature sensors 20 into digital data, and outputs the detected brake temperature to the calculator 33 .

The vehicle information acquisition unit 32 outputs a brake signal to the calculation unit 33 when a signal indicating the energized state of the brake lamp 61 is input, and outputs a brake signal to the calculation unit 33 when the signal indicating the energized state of the brake lamp 61 is not input. A brake signal is not output to the calculation unit 33 .

The vehicle information acquisition unit 32 also calculates the position of the vehicle using the GPS signal input from the GPS receiver 62, and calculates the vehicle speed from changes in the position of the vehicle. The vehicle information acquisition unit 32 then outputs the calculated vehicle speed to the calculation unit 33 . Furthermore, the vehicle information acquisition unit 32 uses the acceleration signal input from the acceleration sensor 63 to calculate the inclination angle of the road surface on which the vehicle is running, and outputs the calculated inclination angle to the calculation unit 33 .

The computing unit 33 is mainly configured by a microcomputer including a CPU 331 and a memory 332 which is a semiconductor memory. The calculation unit 33 is realized by executing a program stored in the memory 332 by the CPU 331 . In the present embodiment, the calculation unit 33 implements functions of a slope calculation unit, a slope abnormality determination unit, a slope determination unit, a vehicle state determination unit, a threshold value setting unit, and a temperature abnormality determination unit.

The CPU 331 executes a program to realize various functions, so that the calculation unit 33 executes drum brake abnormality detection processing. That is, the calculation unit 33 uses various types of information input from the AD conversion unit 31 and the vehicle information acquisition unit 32 to determine whether there is an abnormality in the drum brake. At that time, the moving average of the latest K brake temperature values detected by the temperature sensor 20 is taken, and the moving average value is used as the brake temperature. K is a natural number, and is assumed to be 10, for example.

Then, the calculation unit 33 notifies the determination result via the warning device 4 and the display device 34 . The determination result includes information indicating whether or not the drum brake is abnormal, and which drum brake among the plurality of drum brakes is abnormal. The details of the drum brake abnormality detection process will be described later.

The display device 34 includes a liquid crystal panel or an organic EL panel. When the determination result indicating the drum brake abnormality is input from the calculation unit 33, the display device 34 notifies the drum brake abnormality and also notifies which drum brake among the plurality of drum brakes is abnormal. .

The warning device 4 is, for example, an indicator, and is arranged at a position in the vehicle where the driver can see it through the side mirror. When the determination result indicating the abnormality of the drum brake is input from the calculation unit 33, the warning device 4 lights or blinks to notify the abnormality of the drum brake. After visually confirming the abnormality notification by the warning device 4, the driver can recognize which drum brake has the abnormality by stopping the vehicle and checking the display device 34. - 特許庁

<2. Processing>
<2-1. Abnormality Detection Processing>
Next, a processing procedure of drum brake abnormality detection processing executed by the calculation unit 33 will be described with reference to the flowchart of FIG. 2 . In this embodiment, the calculation unit 33 executes this processing procedure at preset intervals (for example, 1s intervals). Note that the cycle in which this processing procedure is executed is called a processing cycle.

In S<b>10 , the brake temperature of each drum brake is acquired via the AD converter 31 .
Subsequently, in S20, various parameters used for abnormality determination are calculated. Specifically, various determination values and determination value calculation periods are calculated as various parameters. The various determination values include the temperature gradient of the brake temperature, the amount of deviation from the temperature gradient of other brake temperatures, the length of the locus during the calculation period, and the amount of deviation from the length of the locus of other brake temperatures.

When the drum brake is in the dragging state, the temperature gradient (more specifically, the gradient of increase) of the brake temperature is greater than when the drum brake is in the normal state. Therefore, when the drum brake is in a dragging state, a large temperature gradient may occur before the brake temperature reaches a temperature threshold, which will be described later. Therefore, by using the temperature gradient as the determination value, an abnormality in the brake can be detected early.

The trajectory length is the length of the trajectory indicating the fluctuation of the brake temperature, that is, the length of the change curve of the brake temperature during the calculation period. In other words, the locus length is the total sum of changes in the brake temperature during the locus length calculation period. The amount of change in brake temperature is the amount of change between processing cycles. When the drum brake is in the dragging state, the brake temperature fluctuates more than when the drum brake is in the normal state. Even if the brake temperature drops due to wind or water droplets such as rainwater while the vehicle is running, the locus length increases by the temperature change. That is, the trajectory length becomes longer when the fluctuation of the brake temperature is large. Therefore, by using the trajectory length as the determination value, it is possible to detect an abnormality in the brake at an early stage.

The deviation amount is the difference between the determination value for one drum brake among the plurality of drum brakes and the determination value for the other drum brakes. If all drum brakes are normal, it is considered that all drum brakes undergo similar temperature changes. Therefore, there is a high possibility that a drum brake whose temperature changes deviate from other drum brakes is in an abnormal state. By using the deviation amount of the temperature gradient and the deviation amount of the trajectory length as the determination values, the abnormality of the drum brake can be detected early.

The calculation period is a period that changes according to the vehicle speed. Specifically, the higher the vehicle speed, the shorter the calculation period. For example, the calculation period is 10 seconds at a speed of 50 km/h. The temperature gradient calculation period and the locus length calculation period may be different periods.
Subsequently, in S30, a gradient threshold value for judging the abnormality of the drum brake is calculated using the temperature gradient according to at least one of the gradient of the road surface on which the vehicle is running and the state of the vehicle. Details of the gradient threshold calculation process will be described later.

Subsequently, in S40, for each of the plurality of drum brakes, the various parameters calculated in S20 and the current brake temperature value are compared with the corresponding threshold values to determine whether or not each drum brake is abnormal. The various thresholds include the slope threshold, temperature threshold, slope deviation threshold, trajectory length threshold, and length deviation threshold calculated in S30. Each of the various thresholds is a threshold set for determining the abnormal state of the drum brake.

Specifically, it is determined whether any one of the following conditions (1) to (5) is satisfied. (1) The temperature gradient is greater than the gradient threshold. (2) the current brake temperature value is greater than the temperature threshold; (3) The deviation amount of the temperature gradient is larger than the gradient deviation threshold. (4) The trajectory length is greater than the trajectory length threshold. (5) The deviation amount of the trajectory length is greater than the length deviation threshold. If none of the conditions (1) to (5) are satisfied for all the drum brakes, it is determined that all the drum brakes are normal, and this processing is terminated.

On the other hand, if any one of the conditions (1) to (5) is satisfied in any drum brake, the process proceeds to S50. In S50, it is notified that an abnormality in the drum brake has been detected. At this time, in order to suppress erroneous reporting, the abnormality may be reported on the condition that the abnormality of the drum brake is continuously detected in two processing cycles. Specifically, the warning device 4 is activated, and the display device 34 displays the position of the drum brake in which an abnormality has been detected among the plurality of drum brakes and the content of the abnormality, that is, which of the conditions (1) to (5). Display whether it is established. As a result, the parts requiring maintenance are notified, so that maintainability is improved. Further, the position of the drum brake where the abnormality is detected and the contents of the abnormality are stored in the memory 332 . The information stored in memory 332 can be used for failure analysis at a later date. This completes the processing.

<2-2. Gradient Threshold Calculation Processing>
Next, the gradient threshold value calculation process executed by the calculation unit 33 in S30 will be described with reference to the flowchart of FIG. Note that the gradient deviation threshold, the trajectory length threshold, and the length deviation threshold may be calculated in the same manner as the gradient threshold. On the other hand, the temperature threshold is set to a constant value.

First, in S100, the gradient threshold is set to BASE, which is a reference value.
Subsequently, in S110, it is determined whether or not the stop determination flag is ON. If it is determined that the stop determination flag is ON, the process proceeds to S130. On the other hand, when it is determined that the stop determination flag is off, the process proceeds to S120.

In S120, it is determined whether or not the downhill determination flag is on. If it is determined that the downhill determination flag is ON, the process proceeds to S130. On the other hand, if it is determined that the downhill determination flag is off, the process proceeds to S140.

In S130, the gradient threshold value is set to a value ten times BASE, and the process ends. A value of 10 times BASE is a value that the temperature gradient (specifically, the rising gradient) of the brake temperature does not exceed. That is, setting the gradient threshold to a value ten times BASE essentially stops the drum brake abnormality determination using the temperature gradient of the brake temperature in the process of S40.

Similarly to the gradient threshold, by calculating the gradient deviation threshold, the trajectory length threshold, and the length deviation threshold, the abnormality determination of the drum brake using the deviation amount of the temperature gradient, the trajectory length, and the deviation amount of the trajectory length is also stopped. . On the other hand, since the temperature threshold is set to a constant value, the drum brake abnormality determination using the brake temperature is not stopped. That is, when the drum brake abnormality determination using the temperature gradient is stopped, the calculation unit 33 executes the drum brake abnormality determination using at least the brake temperature, thereby avoiding omission of the abnormality determination.

In the present embodiment, a value 10 times BASE is set as the gradient threshold value, but other values may be used as long as the temperature gradient does not exceed the value. can be a value.

When the vehicle is stationary, there is no running wind to cool the drum brakes, so the brake temperature rises significantly, and the brake temperature rise gradient can be similar to that in the case of drag. In addition, when the road surface is downhill, braking by the drum brake is frequently performed, and a brake temperature rise gradient similar to that in the case of a drag state may occur. Therefore, when the vehicle stop determination flag is on and the downhill determination flag is on, the drum brake abnormality determination using the temperature gradient of the brake temperature is stopped.

Also, in S140, it is determined whether or not the brake determination flag is ON. If it is determined that the brake determination flag is ON, the process proceeds to S150. The brake determination flag is set to ON during and immediately after braking in the brake determination process, which will be described later. On the other hand, if it is determined that the brake determination flag is off, the process ends.

In S150, the gradient threshold value is set to twice the value of BASE, and the process ends. During and immediately after braking, a gradient of brake temperature rise that is similar to weak drag may occur. Therefore, if the slope threshold is left at BASE, there is a risk that the normal state of the drum brake may be erroneously detected as an abnormal state. Therefore, the slope threshold value is set to twice the value of BASE so as not to erroneously detect the normal state of the drum brake as an abnormal state during and immediately after braking.

<2-3. Stop judgment processing>
Next, the stop determination process executed by the calculation unit 33 in S30 will be described with reference to the flowchart of FIG.

First, in S200, the previous stop determination flag is read from the memory 332, and it is determined whether or not the previous stop determination flag is on. The initial value of the stop determination flag is set to ON.
If the previous stop determination flag is ON, the process proceeds to S210, and if the previous stop determination flag is OFF, the process proceeds to S230.

In S210, it is determined whether or not the vehicle speed is equal to or higher than the first speed threshold. The first speed threshold is a threshold for determining whether or not the vehicle is in a running state, and is set to 5 km/h, for example. If it is determined that the vehicle speed is greater than or equal to the first speed threshold, that is, if it is determined that the vehicle is in a running state, the process proceeds to S220. In S220, the stop determination flag is set to OFF, and the process ends. After that, the process returns to the process of S200, and this process is repeatedly executed. On the other hand, if it is determined that the vehicle speed is less than the first speed threshold, that is, if it is determined that the vehicle is stopped, the process proceeds to S240. In S240, the stop determination flag is set to ON, and the process ends. After that, the process returns to the process of S200, and this process is repeatedly executed.

In S230, it is determined whether or not the vehicle speed is equal to or less than the second speed threshold. The second speed threshold is a threshold for determining whether or not the running state has changed to the stopped state, and is set to 3 km/h, for example. The second speed threshold is set to a value smaller than the first speed threshold in order to have hysteresis.

If it is determined in S230 that the vehicle speed exceeds the second speed threshold, that is, if it is determined that the vehicle is in a running state, the process proceeds to S250. In S250, the stop determination flag is set to OFF, and the process ends. After that, the process returns to the process of S200, and this process is repeatedly executed. On the other hand, if it is determined in S230 that the vehicle speed is equal to or less than the second speed threshold value, that is, if it is determined that the vehicle is in a stopped state, the process proceeds to S240, the stop determination flag is set to ON, and the main control is performed. End the process. After that, the process returns to the process of S200 and restarts this process.

<2-4. Downhill Judgment Processing>
Next, the downhill determination process executed by the calculation unit 33 in S30 will be described with reference to the flowchart of FIG.

First, in S300, the previous downlink determination flag is read from the memory 332, and it is determined whether or not the previous downlink determination flag is off. The initial value of the downhill determination flag is set to OFF. If the previous downhill determination flag is OFF, the process proceeds to S310, and if the previous downhill determination flag is ON, the process proceeds to S330.

In S310, it is determined whether or not the downhill inclination angle of the road surface on which the vehicle is running is greater than or equal to the inclination threshold. The slope threshold is a threshold for determining whether or not the road surface is downhill, and is set to 4.5°, for example. If it is determined that the downward inclination angle is greater than or equal to the inclination threshold value, the process proceeds to S320. On the other hand, when it is determined that the downward inclination angle is less than the inclination threshold value, the process proceeds to S360. In S360, the downlink determination flag is set to OFF, and the process ends. After that, the process returns to the process of S300, and this process is repeatedly executed.

In S320, it is determined whether or not it has been continuously detected during the first time period that the slope angle of the downward slope is equal to or greater than the slope threshold value. The first time is a time for determining whether the road surface is downhill, and is set to 2 seconds, for example. If it is determined that the detection has continued for the first time, the process proceeds to S350, sets the downhill determination flag to ON, and terminates the present process. After that, the process returns to the process of S300, and this process is repeatedly executed. On the other hand, if it is determined that the detection has not continued for the first time, the process proceeds to S360, sets the downhill determination flag to OFF, and terminates this process. After that, the process returns to S300 to repeat this process.

In S330, it is determined whether or not the downhill slope of the road surface is less than the slope threshold. If it is determined that the downward slope angle is less than the slope threshold value, the process proceeds to S340. On the other hand, when it is determined that the downward inclination angle is equal to or greater than the inclination threshold value, the process proceeds to S370. At S370, the downhill determination flag is set to ON, and the process ends. After that, the process returns to the process of S300, and this process is repeatedly executed.

In S340, it is determined whether or not a road surface with an inclination angle that is less than the inclination threshold has been continuously detected for the second time. The second time is a time for determining whether or not the temperature rise associated with braking on a downhill has ended.

FIG. 7 shows time charts of brake temperature and vehicle speed during and after running downhill. Further, FIG. 8 shows a time chart of the temperature gradient of the brake temperature and the brake signal shown in FIG. As shown in FIGS. 7 and 8, when braking is frequently performed on a downhill, heat accumulates in the drum brake, and the brake temperature continues to rise for a while even after the downhill travel is finished. . As a result, even after the vehicle finishes running downhill, the brake temperature rises at a rate similar to that in the dragging state for a while. That is, even after the downhill running is finished, a temperature gradient of the brake temperature exceeding the gradient threshold may occur for a while.

Therefore, even after the downhill running is finished, the downhill determination flag remains set to ON until the heat accumulated in the drum brake cools down. That is, even after the downhill running is completed, the abnormality determination of the drum brake using the temperature gradient is stopped until the second time elapses. Resume brake abnormality determination. The second time is the time until the heat accumulated in the drum brake cools down after the downhill running is finished, and is, for example, 90 seconds.

If it is determined in S340 that detection has continued for the second time period, the process of S360 is executed and this process ends. After that, the process returns to the process of S300, and this process is repeatedly executed. On the other hand, if it is determined that it has not been detected continuously for the second time, the process of S370 is executed and the present process ends. After that, the process returns to S300 to repeat this process.

<2-5. Brake Judgment Processing>
Next, the brake determination process executed by the calculation unit 33 in S30 will be described with reference to the flowchart of FIG.

First, in S400, the previous brake determination flag is read from the memory 332, and it is determined whether or not the previous brake determination flag is on. The initial value of the brake determination flag is set to off. If the previous brake determination flag is OFF, the process proceeds to S410, and if the previous brake determination flag is ON, the process proceeds to S430.

At S<b>410 , it is determined whether or not there is a brake signal input via the vehicle information acquisition unit 32 . If it is determined that the brake signal has been input, the process proceeds to S420. At S420, the brake determination flag is set to ON, and the process ends. After that, the process returns to the process of S400, and this process is repeatedly executed. On the other hand, if it is determined that there is no input of the brake signal, the process proceeds to S460. At S460, the brake determination flag is set to OFF, and the process ends. After that, the process returns to the process of S400, and this process is repeatedly executed.

On the other hand, at S430, it is determined whether or not there is a brake signal input via the vehicle information acquisition section 32. FIG. If it is determined that there is no brake signal input, the process proceeds to S440. On the other hand, if it is determined that there is an input of the brake signal, the process of S420 is executed and this process ends. After that, the process returns to the process of S400, and this process is repeatedly executed.

In S440, it is determined whether or not a state in which no brake signal is input has continued for a third period of time. The third time is a time for determining whether or not the vehicle has just been braked by the drum brake, and is, for example, 30 seconds. If it is determined that the third time has elapsed, the process proceeds to S450. At S450, the brake determination flag is set to OFF, and the process ends. After that, the process returns to the process of S400, and this process is repeatedly executed. On the other hand, if it is determined that the third time has not elapsed, the process proceeds to S420, sets the brake determination flag to ON, and terminates this process. After that, the process returns to S400 and repeats this process. Immediately after braking, the brake determination flag is set to ON because the brake temperature rise gradient may occur to the degree of weak drag.

<3. Effect>
According to this embodiment described above, the following effects are obtained.
(1) The drum brake abnormality determination using the temperature gradient is stopped according to at least one of the road surface inclination and the vehicle state. That is, when there is a possibility that a brake temperature rise gradient similar to that in the case of drum brake drag occurs, the abnormality determination of the drum brake using the temperature gradient is stopped. Therefore, erroneous detection of the normal state of the drum brake as an abnormal state can be avoided, and the detection accuracy of the abnormal state of the drum brake can be improved.

(2) When the magnitude of the downward slope of the road surface is equal to or greater than the slope threshold value, a brake temperature increase gradient similar to that in the case of drag of the drum brake may occur. Therefore, when the magnitude of the downward slope of the road surface is equal to or greater than the slope threshold value, the abnormality determination of the drum brake using the temperature gradient is stopped. As a result, it is possible to avoid erroneously detecting the normal state of the drum brake as an abnormal state.

(3) When the vehicle is frequently braked while traveling on a long downhill, the temperature of the brake continues to rise for several minutes due to residual heat after traveling on the downhill. Therefore, after traveling downhill, the downhill determination flag is kept on for the second time. As a result, it is possible to avoid erroneously detecting a temperature rise that continues after running downhill as a temperature rise due to an abnormality in the drum brake.

(4) Furthermore, even when the vehicle stops after traveling downhill as shown in (3), the same degree of increase in brake temperature as in the case where the drum brake drag occurs can occur. Therefore, when the vehicle is in a stopped state, the abnormality determination of the drum brake using the temperature gradient is stopped. As a result, it is possible to avoid erroneously detecting the normal state of the drum brake as an abnormal state.

(5) During and immediately after braking, the slope threshold is set to twice the value of BASE. As a result, it is possible to avoid erroneously detecting the temperature rise gradient due to a slight drag during and immediately after braking as a temperature rise due to an abnormality in the drum brake.

(6) While the drum brake abnormality determination using the temperature gradient is stopped, the drum brake abnormality determination is performed by comparing the brake temperature with the temperature threshold. Therefore, when the drum brake is in an abnormal state, it is possible to suppress failure to determine the abnormal state.

(Second embodiment)
<1. Difference from First Embodiment>
Since the basic configuration of the second embodiment is the same as that of the first embodiment, description of common configurations will be omitted, and differences will be mainly described. Note that the same reference numerals as in the first embodiment indicate the same configurations, and refer to the preceding description.

The second embodiment differs from the first embodiment in that the calculation unit 33 executes the downhill determination process shown in FIG. 9 instead of the downhill determination process shown in FIG.
<2. Downhill Judgment Processing>
Next, downhill determination processing executed by the calculation unit 33 according to the second embodiment will be described with reference to the flowchart of FIG.

First, in S500-S530 and S550-S570, the same processing as in S300-S330 and S350-S370 is executed. On the other hand, in S540, a process different from S340 is executed. If it is determined in S530 that the downward inclination angle is less than the inclination threshold, the process proceeds to S540. On the other hand, if it is determined that the downward slope angle is greater than or equal to the slope threshold value, the process of S570 is executed and the process ends.

In S540, it is determined whether or not the brake temperature has stopped increasing. If the drum brakes are normal, the increase in brake temperature will stop after a while after traveling downhill. Therefore, in the present embodiment, it is determined whether or not the heat accumulated in the drum brakes has cooled down, using the increase in the brake temperature instead of the elapsed time after the downhill travel is completed. That is, the drum brake abnormality determination using the temperature gradient is stopped until the brake temperature stops increasing, and the drum brake abnormality determination using the temperature gradient is restarted after the brake temperature stops increasing.

If it is determined in S540 that the temperature rise has stopped, the process of S560 is executed and this process ends. On the other hand, if it is determined that the temperature rise has not stopped, the process of S570 is executed and this process ends. After the processing of S550, S560, and S570, the processing returns to S500 to repeat this processing.

According to the second embodiment described above, the same effects as the effects (1) to (6) of the first embodiment described above can be obtained.
(Third embodiment)
<1. Difference from First Embodiment>
Since the basic configuration of the third embodiment is the same as that of the first embodiment, the description of the common configuration will be omitted, and the differences will be mainly described. Note that the same reference numerals as in the first embodiment indicate the same configurations, and refer to the preceding description.

The third embodiment differs from the first embodiment in that the calculation unit 33 executes the downhill determination process shown in FIG. 10 instead of the downhill determination process shown in FIG.
<2. Downhill Judgment Processing>
Next, downhill determination processing executed by the calculation unit 33 according to the third embodiment will be described with reference to the flowchart of FIG.

First, in S600-S630 and S650-S670, the same processing as in S300-S330 and S350-S370 is executed. On the other hand, in S640, a process different from S340 is executed. Further, when the brake signal is input while the downhill determination flag is on, the timer in the CPU 331 is used to count and integrate the input time of the brake signal. That is, it counts the total input time of the brake signal while the downhill determination flag is on.

In S630, it is determined whether or not the downward slope angle is less than the slope threshold value. If it is determined in S630 that the downward inclination angle is greater than or equal to the inclination threshold value, the process of S670 is executed and the process ends. On the other hand, when it is determined that the downward slope angle is less than the slope threshold value, the process proceeds to S640.

In S640, it is determined whether or not a brake-on period or more has elapsed while the downhill determination flag is ON after detecting a road surface with an inclination angle that is less than the inclination threshold. The brake-on period corresponds to a count value counted using a timer.

The amount of heat generated by the drum brake is proportional to the brake-on period. The greater the amount of heat generated by the drum brakes, the longer the brake temperature continues to rise after the downhill running is completed. Therefore, in this embodiment, instead of comparing the elapsed time from the end of downhill travel with the predetermined second time, the elapsed time is compared with the braking period while the downhill determination flag is on. As a result, when the amount of heat generated by the drum brake is relatively small, the stop period of the drum brake abnormality determination using the temperature gradient is relatively short, and when the amount of heat generated by the drum brake is relatively large, the stop period can be relatively long.

If it is determined in S640 that the braking period during which the downhill determination flag is ON has elapsed since the downhill travel was completed, the process of S660 is executed and this process ends. On the other hand, if it is determined that the braking period has not elapsed, the process of S670 is executed and the process ends. After the processing of S650, S660, and S670, the processing returns to S600 to repeat this processing.

According to the third embodiment described above, the following effects can be obtained in addition to the effects (1) to (6) of the first embodiment described above.
(7) The longer the braking period is, the longer the ON period of the downhill determination flag is, so that the stop period of the drum brake abnormality determination using the temperature gradient can be lengthened. Therefore, erroneous detection of the normal state of the drum brake as an abnormal state can be more reliably avoided. Further, when the braking period is short and the amount of heat generated by the drum brakes is small, it is possible to restart the abnormality determination of the drum brakes using the temperature gradient at an earlier timing. As a result, it is possible to increase the chances of early detection of the dragging state of the drum brake.

(Fourth embodiment)
<1. Difference from First Embodiment>
Since the basic configuration of the fourth embodiment is the same as that of the first embodiment, the description of the common configuration will be omitted, and the differences will be mainly described. Note that the same reference numerals as in the first embodiment indicate the same configurations, and refer to the preceding description.

The fourth embodiment differs from the first embodiment in that the calculation unit 33 executes the gradient threshold calculation process shown in FIG. 11 instead of the gradient threshold calculation process shown in FIG. Furthermore, the fourth embodiment differs from the first embodiment in that the calculation unit 33 executes the downhill determination process shown in FIG. 12 instead of the downhill determination process shown in FIG.

<2. Processing>
<2-1. Gradient Threshold Calculation Processing>
Next, gradient threshold value calculation processing executed by the calculation unit 33 according to the fourth embodiment will be described with reference to the flowchart of FIG. 11 .

First, in S700, S710, S720 and S730, the same processing as in S100, S110, S130 and S120 is executed.
If it is determined in S730 that the downhill determination flag is ON, the process proceeds to S740. On the other hand, if it is determined that the downhill determination flag is off, the process proceeds to S750.

In S740, the gradient threshold value is set to a value that is N times BASE, and this process ends. After that, the process returns to the process of S700, and this process is repeatedly executed. A variable N is a natural number, and is a value set in the downhill determination process, which will be described later.

Also, in S750 and S760, the same processing as in S140 and S150 is executed.
<2-2. Downhill Judgment Processing>
Next, downhill determination processing executed by the calculation unit 33 according to the fourth embodiment will be described with reference to the flowchart of FIG. 12 .

First, in S800, S810, S820, S850 and S860, the same processing as in S300, S310, S320, S350 and S360 is executed.
After the downhill determination flag is set to ON in S850, the process proceeds to S870, 10 is set to the variable N, and this process ends. After that, the process returns to the process of S800, and this process is repeatedly executed.

If it is determined in S800 that the previous downward slope determination flag is ON, the process proceeds to S830 to determine whether or not the downward inclination angle of the road surface on which the vehicle is traveling is equal to or greater than the inclination threshold value. If it is determined in S830 that the downward slope angle is greater than or equal to the slope threshold value, the process proceeds to S840. In S840, after setting the downhill determination flag to ON, the process proceeds to S960. In S960, the variable N is set to 10, and the process ends. After that, the process returns to the process of S800, and this process is repeatedly executed.

If it is determined in S830 that the downward slope angle is less than the slope threshold value, the process proceeds to S880. In S880, it is determined whether or not a road surface with an inclination angle less than the inclination threshold has been detected continuously for the sixth time. The sixth time is a time for judging whether or not a sufficient time has passed for the temperature rise of the brake to converge after the downhill running is finished, and is, for example, 120 seconds. If it is determined in S880 that detection has continued for the sixth time, the process proceeds to S890, the downhill determination flag is set to OFF, and this process ends. After that, the process returns to the process of S800, and this process is repeatedly executed. On the other hand, if it is determined in S880 that detection has not continued for the sixth time, the process proceeds to S900.

In S900, it is determined whether or not a road surface with an inclination angle less than the inclination threshold has been detected continuously for the fifth time. The fifth time is a time for determining whether or not the second stage has been reached after the downhill running is finished, and is, for example, 60 seconds. If it is determined in S900 that detection has continued for the fifth time, the process proceeds to S910, the downhill determination flag is set to ON, and the process proceeds to S920. In S920, the variable N is set to 2, and the process ends. After that, the process returns to the process of S800, and this process is repeatedly executed.

On the other hand, if it is determined in S900 that detection has not continued for the fifth time, the process proceeds to S930.
In S930, it is determined whether or not a road surface with an inclination angle less than the inclination threshold has been detected continuously for the fourth time. The fourth time is a time for judging whether or not the downhill running has ended and the first stage has been reached, and is, for example, 30 seconds. If it is determined in S930 that detection has continued for the fourth time, the process proceeds to S940, sets the downhill determination flag to ON, and proceeds to the process of S950. In S950, the variable N is set to 3, and the process ends. After that, the process returns to the process of S800, and this process is repeatedly executed.

On the other hand, if it is determined in S930 that the detection has not continued for the fourth time, the process proceeds to S840, the downhill determination flag is set to ON, and the process proceeds to S960. In S960, the variable N is set to 10, and the process ends. After that, the process returns to the process of S800, and this process is repeatedly executed.

Thus, in this embodiment, the detection of a road surface with an inclination angle less than the inclination threshold is used as a trigger for switching the downhill determination flag from on to off. Then, after the trigger is detected, the value of the variable N is gradually decreased with the lapse of time, and finally the downhill determination flag is switched from ON to OFF.

According to the fourth embodiment described above, the following effects can be obtained in addition to the effects (1) to (6) of the first embodiment described above.
(8) After detecting a road surface with an inclination angle less than the inclination threshold, the inclination threshold is set to be gradually decreased over time. Therefore, when the influence of the residual heat becomes smaller with the lapse of time, the temperature gradient can be used to detect the abnormality of the drum brake. As a result, an abnormality in the drum brake can be detected at an earlier timing using the temperature gradient.

(Other embodiments)
Although the embodiments for implementing the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and can be implemented with various modifications.

(a) In the above embodiment, the drum brake abnormality determination using the temperature gradient was substantially stopped by setting the gradient threshold to an impossibly large value. The means for stopping determination is not limited to this. For example, in the processing of S30, the comparison between the temperature gradient and the gradient threshold may be stopped. Alternatively, the determination result of comparing the temperature gradient and the gradient threshold may be invalidated. Stopping the abnormality determination of the drum brakes using the temperature gradient is to stop effective abnormality determination of the drum brakes using the temperature gradient, and any means may be used.

(b) In the above embodiment, the vehicle speed is calculated using GPS reception signals, but the vehicle may be equipped with wheel speed sensors and the vehicle speed may be calculated from the detection signals of the wheel-side sensors. Alternatively, the vehicle speed may be calculated from the acceleration in the traveling direction of the vehicle detected by the acceleration sensor 63 . In the above embodiment, the brake signal is detected from the presence or absence of energization of the brake lamp 61, but an air pressure sensor is mounted in the air pipe of the drum brake, and the brake signal is detected from the change in air pressure detected by the air pressure sensor. You may

(c) the brake anomaly detection apparatus 3 and techniques thereof described in the present disclosure are provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program; It may also be implemented by a dedicated computer. Alternatively, the brake anomaly detection apparatus 3 and techniques thereof described in the present disclosure may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the brake anomaly detection device 3 and techniques thereof described in the present disclosure may include a processor configured by a processor and memory programmed to perform one or more functions and one or more hardware logic circuits. may be implemented by one or more dedicated computers configured by a combination of Computer programs may also be stored as computer-executable instructions on a computer-readable non-transitional tangible storage medium. The method of realizing the function of each part included in the brake abnormality detection device 3 does not necessarily include software, and all the functions may be realized using one or more pieces of hardware. .

(d) A plurality of functions possessed by one component in the above embodiment may be realized by a plurality of components, or a function possessed by one component may be realized by a plurality of components. . Also, a plurality of functions possessed by a plurality of components may be realized by a single component, or a function realized by a plurality of components may be realized by a single component. Also, part of the configuration of the above embodiment may be omitted. Moreover, at least part of the configuration of the above embodiment may be added or replaced with respect to the configuration of the other above embodiment.

(e) In addition to the brake abnormality detection device described above, a system having the brake abnormality detection device as a component, a program for causing a computer to function as the brake abnormality detection device, and a non-transitional device such as a semiconductor memory in which this program is recorded The present disclosure can also be implemented in various forms such as a physical recording medium and a method for detecting brake abnormality.

3 -- brake abnormality detection device, 31 -- AD conversion section, 32 -- vehicle information acquisition section, 33 -- calculation section.

Claims (6)

a temperature detection unit (31, S10) for detecting a brake temperature, which is the temperature of a drum brake provided on an axle of a vehicle;
a gradient calculator (33, S20) for calculating a temperature gradient of the brake temperature detected by the temperature detector during a preset calculation period;
a threshold calculation unit (33, S30) for calculating a slope threshold according to at least one of the slope of the road surface on which the vehicle is traveling and the state of the vehicle;
a gradient abnormality determination unit (33, S40) that determines that the drum brake is abnormal when the temperature gradient calculated by the gradient calculation unit is larger than the gradient threshold value calculated by the threshold calculation unit;
a slope determination unit (32, 33, S310, S330, S510, S530, S610, S630, S810, S830) that determines whether or not the magnitude of the downward slope of the road surface is equal to or greater than a predetermined value;
with
The gradient abnormality determination section (33, S40) determines abnormality of the drum brake using the temperature gradient when the inclination determination section determines that the magnitude of the downward slope is equal to or greater than the predetermined value. Stop,
Brake abnormality detection device. The threshold calculation unit (33, S150, S760) calculates the slope threshold to be higher than a reference value immediately after the braking of the vehicle by the drum brake is completed .
The brake abnormality detection device according to claim 1 . a temperature detection unit (31, S10) for detecting a brake temperature, which is the temperature of a drum brake provided on an axle of a vehicle;
a gradient calculator (33, S20) for calculating a temperature gradient of the brake temperature detected by the temperature detector during a preset calculation period;
a threshold calculation unit (33, S30) for calculating a slope threshold according to at least one of the slope of the road surface on which the vehicle is traveling and the state of the vehicle;
a gradient abnormality determination unit (33, S40) that determines that the drum brake is abnormal when the temperature gradient calculated by the gradient calculation unit is larger than the gradient threshold calculated by the threshold calculation unit. ,
The gradient abnormality determination unit (33, S40) stops the abnormality determination of the drum brake using the temperature gradient according to at least one of the inclination of the road surface on which the vehicle is running and the state of the vehicle,
The threshold calculation unit (33, S150, S760) calculates the slope threshold to be higher than a reference value immediately after the braking of the vehicle by the drum brake is completed.
Brake abnormality detection device. a temperature abnormality determination unit (33, S40) that determines that the drum brake is abnormal when the brake temperature detected by the temperature detection unit is higher than a temperature threshold;
The temperature abnormality determination unit executes the abnormality determination of the drum brake when the gradient abnormality determination unit stops the abnormality determination of the drum brake.
The brake abnormality detection device according to any one of claims 1 to 3 . a temperature detection unit (31, S10) for detecting a brake temperature, which is the temperature of a drum brake provided on an axle of a vehicle;
a gradient calculator (33, S20) for calculating a temperature gradient of the brake temperature detected by the temperature detector during a preset calculation period;
a threshold calculation unit (33, S30) for calculating a slope threshold according to at least one of the slope of the road surface on which the vehicle is traveling and the state of the vehicle;
a gradient abnormality determination unit (33, S40) that determines that the drum brake is abnormal when the temperature gradient calculated by the gradient calculation unit is larger than the gradient threshold value calculated by the threshold calculation unit;
a temperature abnormality determination unit (33, S40) that determines that the drum brake is abnormal when the brake temperature detected by the temperature detection unit is higher than a temperature threshold;
with
The gradient abnormality determination unit (33, S40) stops the abnormality determination of the drum brake using the temperature gradient according to at least one of the inclination of the road surface on which the vehicle is running and the state of the vehicle,
The temperature abnormality determination unit executes the abnormality determination of the drum brake when the gradient abnormality determination unit stops the abnormality determination of the drum brake.
Brake abnormality detection device. A vehicle state determination unit (32, 33, S210, S230) that determines whether the vehicle is in a stopped state,
The gradient abnormality determination unit (33, S40) stops abnormality determination of the drum brake using the temperature gradient when the vehicle state determination unit determines that the vehicle is in a stopped state.
The brake abnormality detection device according to any one of claims 1 to 5 .

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