JP2007137303A - Wheel abnormality detection device based on time-series parameter change - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel abnormality detection device which uses a traditional wheel stroke sensor and a wheel up-and-down direction acceleration sensor, which can accurately detect the occurrence of a breakdown of the traditional wheel stroke sensor and the wheel up-and-down direction acceleration sensor or a wheel blowout, and which can detect the attachment of non-slip chains without errors. <P>SOLUTION: Either the displacement of each wheel in the up-and-down direction or the acceleration of each wheel in the up-and-down direction with respect to a vehicle body is detected in chronological order. Then a time-series change value detected for one wheel is compared to time-series change values detected for a plurality of the other wheels. When the difference exceeds a predetermined threshold value, it is judged that there is an abnormality with the one wheel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wheel abnormality detection device that detects an abnormality that has occurred in a wheel of a vehicle such as an automobile. However, the wheel abnormality targeted by the present invention is a failure of a stroke sensor for detecting the vertical displacement of the wheel relative to the vehicle body or a vertical acceleration sensor for detecting the vertical acceleration of the wheel, tire puncture or distortion, and common sense. Although it cannot be said that the wheel is abnormal, the installation of the non-slip chain includes the installation of the non-slip chain since the installation of the anti-slip chain is not normal.

Foreground control of the suspension of the rear wheels based on the vibrations of the front wheels of the front-wheel drive vehicle is performed. In the vehicle to be used, the vertical movement of the front wheel and the rear wheel is detected, and based on the difference, it is detected whether or not the anti-slip chain is attached to the front wheel, and the above control is performed. It is described in. In this case, the output of the vehicle height sensor for the four wheels on the front, rear, left and right is guided to the FFT, from which the magnitude of the component in the specific frequency band is calculated, In this case, it is determined whether or not the non-slip chain is attached.
Japanese Patent Laid-Open No. 6-80006

  The vertical displacement and vertical acceleration of each wheel that occurs during the traveling of a vehicle having four wheels with tires such as an automobile is such that the left and right wheels are separated from each other by the tread dimension in the vehicle width direction, and the front and rear wheels are in the front and rear direction. Because they are separated from each other by the wheelbase dimensions, they do not exist on the same road surface at the same moment, and the tire-equipped wheels are vibrated and deformed with their own spring constants. Because it occurs in a time difference, simply comparing the detected value of vertical displacement and vertical acceleration of each wheel or the component of its specific frequency band, it is influenced by the difference of each other and mutual time difference. There is a failure in the stroke sensor or vertical acceleration sensor for one of these wheels, or one of the tires is punctured, or an anti-slip chain is installed. Error prone to determine whether it is.

  In view of the above circumstances, the present invention eliminates the need for adding a special hardware device to the conventional stroke sensor or vertical acceleration sensor, and accurately detects it when a failure occurs or when a wheel is punctured. It is an object of the present invention to provide a wheel abnormality detection device that can detect and detect it without error when the anti-slip chain is mounted.

  In order to solve the above-described problems, the present invention provides a wheel abnormality detection device for detecting an abnormality occurring in each wheel of a vehicle having four or more wheels with tires. Alternatively, either one of the vertical accelerations of each wheel is detected in time series, and the time series change value detected for one wheel is compared with the time series change values detected for other wheels, The present invention proposes a wheel abnormality detection device characterized by determining that there is an abnormality in the one wheel when the difference exceeds a predetermined limit value.

  The time-series change value may be a maximum value of vertical displacement detected for a predetermined number of times or for a predetermined period by predetermined periodic detection for each wheel.

  In this case, when the maximum value of the vertical displacement of one of the wheels is smaller than the average value of the maximum vertical displacement of the other plurality of wheels by a predetermined value or more, an abnormality is detected in the stroke sensor of the one wheel. It may be determined that there is.

  Further, in this case, when the maximum value of the vertical displacement of one of the wheels is larger than the average value of the maximum vertical displacement of the other wheels by a predetermined value or more, the tire of the one wheel is punctured. It may be determined that

  Further, in this case, when the maximum value of the vertical displacement of the driving wheel among the wheels is larger than the maximum value of the vertical displacement of the non-driving wheel by a predetermined value or more, it is determined that the non-slip chain is attached to the driving wheel. May be.

  Alternatively, the time-series change value may be a maximum value of the vertical acceleration detected for a predetermined number of times or for a predetermined period by predetermined periodic detection for each wheel.

  In this case, when the maximum vertical acceleration value of one of the wheels is smaller than the average value of the maximum vertical acceleration values of other wheels by a predetermined value or more, the vertical acceleration sensor of the one wheel is used. It may be determined that there is an abnormality.

  Further, in this case, when the maximum vertical acceleration value of one of the wheels is larger than the average value of the maximum vertical acceleration values of other wheels by a predetermined value or more, the tire of the one wheel is punctured. It may be determined that

  Further, in this case, when the maximum value of the vertical acceleration of the driving wheel among the wheels is larger than the maximum value of the vertical acceleration of the non-driving wheel by a predetermined value or more, it is determined that the non-slip chain is attached to the driving wheel. May be.

  Furthermore, the time-series change value may be an amplitude with respect to a specific frequency when the distribution of the vertical displacement detected for a predetermined number of times or for a predetermined period is replaced with a frequency distribution for each wheel.

  In this case, the amplitude with respect to the first specific frequency in the frequency distribution of one of the wheels is larger than the average value of the amplitude with respect to the first specific frequency in the frequency distribution of other wheels. When it is larger than a predetermined value, it may be determined that the tire of the one wheel is punctured.

  Further, in this case, the amplitude for the second specific frequency in the frequency distribution of the driving wheel among the wheels is larger than the amplitude for the second specific frequency in the frequency distribution of the non-driving wheel by a predetermined value or more. Sometimes it may be determined that a non-slip chain is attached to the drive wheel.

  Alternatively, in this case, when all the wheels are drive wheels and the amplitude of each wheel with respect to the third specific frequency in the frequency distribution is a predetermined value or more, a chain is attached to all of the drive wheels. It may be determined that

  In addition, the time-series change value may be an amplitude with respect to a specific frequency when the distribution of the vertical acceleration detected for a predetermined number of times or for a predetermined period is replaced with a frequency distribution for each wheel.

  In this case, the amplitude with respect to the fourth specific frequency in the frequency distribution of one of the wheels is greater than the average value of the amplitude with respect to the fourth specific frequency in the frequency distribution of other wheels. When it is larger than a predetermined value, it may be determined that the tire of the one wheel is punctured.

  Further, in this case, the amplitude for the fifth specific frequency in the frequency distribution of the driving wheel of each wheel is larger than the amplitude for the fifth specific frequency in the frequency distribution of the non-driving wheel by a predetermined value or more. Sometimes it may be determined that a non-slip chain is attached to the drive wheel.

  Alternatively, in this case, when each wheel is a driving wheel and the amplitude for the sixth specific frequency in the frequency distribution of each wheel is equal to or greater than a predetermined value, a slip-proof chain is attached to all the driving wheels. It may be determined that

  As described above, in the wheel abnormality detection device for detecting an abnormality occurring in each wheel of a vehicle having four or more wheels with tires, the vertical displacement of each wheel relative to the vehicle body or the vertical acceleration of each wheel is detected. Any one is detected in time series, and the time series change value detected for one wheel is compared with the time series change value detected for other wheels, and the difference exceeds a predetermined limit value. If it is determined that there is an abnormality in the wheel at one time, the time-series change value is a value over a certain appropriate time so as to cover the wheel base distance while the vehicle travels. Thus, the detected value of the vertical displacement or the vertical acceleration for each one wheel is substantially the same as the detected value of the vertical displacement or the vertical acceleration for a plurality of other wheels traveling on the same road surface. In Can be compared Te, it can be eliminated that an error occurs in the abnormality determination by the difference due to the staggered offset between differences and mutual driving conditions of each in the comparative wheels.

  If the time-series change value is the maximum value of the vertical displacement detected for a predetermined number of times or for a predetermined period by predetermined periodic detection for each wheel, in addition to the advantage of the determination based on the time-series change value described above. Thus, when an abnormality occurs in the detection of the vertical displacement of the wheel, the abnormality can be more reliably determined without being confused by noise.

  In this case, when the maximum value of the vertical displacement of one of the wheels is smaller than the average value of the maximum vertical displacement of the other plurality of wheels by a predetermined value or more, an abnormality is detected in the stroke sensor of the one wheel. If it is determined that the stroke sensor is abnormal, the abnormality of the stroke sensor is usually a decrease in the output thereof, so that the wheel abnormality can be identified and detected as a failure of the stroke sensor.

  Further, in this case, when the maximum value of the vertical displacement of one of the wheels is larger than the average value of the maximum vertical displacement of the other wheels by a predetermined value or more, the tire of the one wheel is punctured. If the tire is punctured, the outer shape of the wheel becomes elliptical when the tire is punctured, so that the displacement in the vertical direction of the wheel is increased. Thus, the wheel abnormality can be identified and detected as tire puncture.

  Furthermore, in this case, when the maximum value of the vertical displacement of the driving wheel of each wheel is larger than the maximum value of the vertical displacement of the non-driving wheel by a predetermined value or more, the non-slip chain is attached to the driving wheel. If it is determined, when the non-slip chain is mounted on the drive wheel, the vertical displacement of the drive wheel increases due to the unevenness of the chain, so that the wheel abnormality is identified as the installation of the non-slip chain on the drive wheel. Can be detected.

  Further, if the time-series change value is the maximum value of the vertical acceleration detected for a predetermined number of times or for a predetermined period for each wheel, the advantage of the determination based on the time-series change value is provided. In addition, when an abnormality occurs in the detection of the vertical acceleration of the wheel, the abnormality can be more reliably determined without being confused by noise.

  Also in this case, when the maximum value of the vertical acceleration of one of the wheels is smaller than the average value of the maximum vertical acceleration of other wheels by a predetermined value or more, the acceleration sensor of the one wheel If it is determined that there is an abnormality, the abnormality of the vertical acceleration sensor is also usually a decrease in the output thereof, so that the wheel abnormality can be identified and detected as a failure of the vertical acceleration sensor.

  Also in this case, when the maximum value of the vertical displacement of one of the wheels is larger than the average value of the maximum vertical displacement of other wheels by a predetermined value or more, the tire of the one wheel If it is determined that the tire is punctured, the ovalization of the outer shape of the wheel due to the tire puncture also increases the acceleration in the vertical direction of the wheel, so that the wheel abnormality can be identified and detected as a tire puncture.

  Furthermore, in this case, when the maximum value of the vertical acceleration of the driving wheel among the wheels is larger than the maximum value of the vertical acceleration of the non-driving wheel by a predetermined value or more, the non-slip chain is attached to the driving wheel. If the determination is made, the attachment of the non-slip chain to the drive wheel also increases the vertical acceleration of the drive wheel, so that it is possible to detect and detect the wheel abnormality as the attachment of the non-slip chain to the drive wheel. .

  Further, if the time-series change value is an amplitude with respect to a specific frequency when the distribution of the vertical displacement detected for a predetermined number of times or for a predetermined period by a predetermined periodic detection for each wheel is replaced with a frequency distribution, In addition to the advantages of determination based on the time-series change value, by appropriately setting a specific frequency according to the type of abnormality to be determined, the occurrence of the abnormality can be determined more significantly while specifying the type of abnormality. Can do.

  In this case, the amplitude with respect to the first specific frequency in the frequency distribution of one of the wheels is larger than the average value of the amplitude with respect to the first specific frequency in the frequency distribution of other wheels. If it is determined that the tire of the one wheel is punctured when larger than a predetermined value, in addition to the above-mentioned advantage of detecting tire puncture in time series based on an increase in the vertical displacement of the wheel, the first By appropriately setting the specific frequency to the period of the vertical displacement of the wheel caused by the tire puncture, it is possible to determine the occurrence of the tire puncture more remarkably while identifying the tire puncture.

  Further, in this case, the amplitude for the second specific frequency in the frequency distribution of the driving wheel among the wheels is larger than the amplitude for the second specific frequency in the frequency distribution of the non-driving wheel by a predetermined value or more. If it is determined that the non-slip chain is attached to the drive wheel, it is detected in time series that the vertical displacement of the drive wheel is greater than the vertical displacement of the non-drive wheel due to the attachment of the non-slip chain. In addition to the above-mentioned advantages, by setting the second specific frequency appropriately with respect to the cycle of the vertical displacement of the wheel caused by the installation of the non-slip chain, the installation of the non-slip chain is specified while the installation is more specific. It can be determined prominently.

  Alternatively, in this case, when each wheel is a drive wheel and the amplitude for the third specific frequency in the frequency distribution of each wheel is equal to or greater than a predetermined value, a slip-proof chain is attached to all the drive wheels. If it is determined that the anti-slip chain is attached, the frequency of the vertical displacement of the wheel increases markedly compared to when the anti-slip chain is not attached. By setting the appropriate value according to the vertical displacement of such high-frequency wheels, it is possible to install a non-slip chain even when the vehicle is a four-wheel drive vehicle and all wheels are equipped with chains. Can be detected.

  Further, even if the time-series change value is an amplitude with respect to a specific frequency when the distribution of the vertical acceleration detected for a predetermined number of times or for a predetermined period is replaced with a frequency distribution for each wheel, In addition to the advantages of determination based on the time-series change value, by appropriately setting a specific frequency according to the type of abnormality to be determined, the occurrence of the abnormality can be determined more significantly while specifying the type of abnormality. Can do.

  In this case, the amplitude with respect to the fourth specific frequency in the frequency distribution of one of the wheels is greater than the average value of the amplitude with respect to the fourth specific frequency in the frequency distribution of other wheels. If it is determined that the tire of the one wheel is punctured when larger than a predetermined value, in addition to the above-mentioned advantage of detecting tire puncture in a time series based on an increase in the vertical acceleration of the wheel, the fourth tire By appropriately setting the specific frequency to the cycle of the change in the vertical acceleration of the wheel caused by the tire puncture, it is possible to determine the occurrence of the tire puncture more remarkably while identifying the tire puncture.

  Also in this case, the amplitude with respect to the fifth specific frequency in the frequency distribution of the driving wheel of each wheel is a predetermined value from the amplitude with respect to the fifth specific frequency in the frequency distribution of the non-driving wheel. If it is determined that the non-slip chain is attached to the driving wheel when the driving wheel is larger than the above, the fact that the vertical acceleration of the driving wheel increases more than the vertical acceleration of the non-driving wheel due to the attachment of the non-slip chain in time series. In addition to the above-mentioned advantages to be detected, the fifth specific frequency is appropriately set with respect to the period of change in the vertical acceleration of the wheel caused by the installation of the non-slip chain, thereby specifying the installation of the non-slip chain. The wearing can be determined more remarkably.

  Alternatively, in this case, when each wheel is a driving wheel and the amplitude for the sixth specific frequency in the frequency distribution of each wheel is equal to or greater than a predetermined value, a slip-proof chain is attached to all the driving wheels. If it is determined that the anti-slip chain is attached, the frequency of change in the vertical acceleration of the wheel also increases significantly compared to when the anti-slip chain is not attached. Is set to an appropriate value in accordance with such high frequency wheel vertical displacement, even when the vehicle is a four-wheel drive vehicle and all wheels are equipped with non-slip chains. The attachment of the stop chain can be detected.

  The attached FIG. 1 shows a wheel abnormality detecting device according to the present invention in a four-wheeled vehicle as an electronic control device (ECU) incorporating a stroke sensor or a load sensor provided for each wheel as a hardware and a microcomputer. It is the schematic which shows the hardware constitutions when implementing by these. In the current four-wheeled vehicle, it is possible to provide a stroke sensor or a load sensor for each of the four wheels, and to provide an electronic control device incorporating a microcomputer in the vehicle for running posture control and other automatic control. Generally done. Accordingly, the illustrated configuration is known as hardware. The present invention uses these hardware already installed in a general four-wheeled vehicle and is incorporated as software in an electronic control unit.

  As shown in the figure, the vertical displacement of each wheel relative to the vehicle body detected by the stroke sensor or load sensor incorporated in each of the left front wheel, right front wheel, left rear wheel, and right rear wheel or the load acting on each wheel is electronic. It is supplied to a wheel abnormality detection unit according to the present invention configured as one function of the control device.

  FIG. 2 is a flowchart showing an example of the control performed in the wheel abnormality detection unit in the electronic control unit of FIG. 1 as one embodiment of the present invention. The control according to this flowchart may be repeated at a cycle of several tens to several hundreds of milliseconds during operation of the vehicle.

  When the control is started, in step 10, the numerical value n for identifying the wheel is reset to 0 at the start of the control, or starting from the state where it is reset to 0 in step 260 of the previous flow, 1 Incremented only. Here, n = 1, 2, 3, and 4 designate the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. Therefore, the calculation that first proceeds with n set to 1 is based on the left front wheel.

  Control then proceeds to step 20 where the count value m is also reset to 0 at the beginning of control, or incremented by 1 from the state reset to 0 in step 80 of the previous flow. The count value m is a value indicating the number of detections repeated to detect the maximum value within a certain period of vertical displacement (suspension stroke) relative to the vehicle body for each wheel.

  Next, the control proceeds to step 30, and the value of the vertical displacement S (n, m) by the m-th detection for n wheels is detected. As shown in parentheses in FIG. 1, when a load sensor is used instead of the stroke sensor, the vertical load (ground contact load) of each wheel detected by the load sensor as S (n, m) is used. ) May be used. Since the vertical displacement and load of the wheel in the suspension correspond uniquely through the spring constant of the suspension, the purpose and function of the present invention are avoided here in order to avoid complicated description. As far as the effect is concerned, it is assumed that the vertical displacement of the wheel and the load are synonymous.

  Next, control proceeds to step 40, where the vertical displacement S (n, m) detected in the current flow is greater than the vertical displacement S (n, m-1) detected in the previous flow. It is determined whether or not it is large. In the first flow where m is 1, there is no previous flow, so the value of S (n, m-1) is 0 set at the start of control or the final value in the previous flow. . If the answer is yes (Y), control proceeds to step 50, where the current S (n, m) is S (n). On the other hand, if the answer is no (N), the control proceeds to step 60, and the previous S (n, m-1) is set to S (n).

  In any case, control then proceeds to step 70, where it is determined whether m is greater than or equal to mo. mo is an upper limit value of the number of detection repetitions m, and a value obtained by multiplying mo by the cycle of the flow repetition is a period (time) for detecting the maximum value of one vertical displacement for the wheel n. While the answer to step 70 is no, the control returns to step 20, the processing of steps 20 to 70 is repeated, and the maximum value of the detected values of S (n) during that time is set to S (n). Thus, the maximum value for S (n) is detected. If the answer to step 70 is yes, control proceeds to step 80 where m is reset to zero.

  Next, at step 90, it is determined whether n is greater than 4. The answer is no until the processing of the four wheels is completed, the control returns to step 10, n is incremented by 1, the detection value object is changed to the next wheel, and steps 20 to 80 are repeated as described above. Thus, n = 1 to 4, that is, the maximum value S (1), S (2), S () of the vertical displacement within a predetermined period for each of the left front wheel, right front wheel, left rear wheel, and right rear wheel. 3) and S (4) are obtained. When the calculation of the maximum value of the vertical displacement for the four wheels is completed and the answer to step 90 is yes, the control proceeds to step 100.

  In step 100, St is calculated by adding S (1), S (2), S (3), and S (4).

  Control then proceeds to step 110 where n is reset to 0, further control proceeds to step 120, n is incremented by 1, and control proceeds to step 130.

  In step 130, Sa (n) is calculated by dividing the value obtained by subtracting S (n) from St by 3. Sa (n) is an average value of the maximum values of the vertical displacements of the other three wheels excluding the n wheels.

  Next, control proceeds to step 140, where it is determined whether S (n) is smaller than Sa (n) by a predetermined deviation ΔS1 or more. If ΔS1 is set to an appropriate value, if the answer is yes, the maximum vertical displacement detected for the n-wheel is the maximum vertical displacement of the other three wheels excluding the n-wheel. It is markedly smaller than the average value of, and it can be suspected that an abnormality has occurred in the stroke sensor (or load sensor) for the n-wheel. However, if it is determined that an abnormality has occurred in the stroke sensor (or load sensor) for the n-wheel immediately after the answer to step 140 becomes once, an erroneous determination may occur. Then, the count value Cf (n) of the sensor failure for the n-wheel is increased by 1 from the state at the start of control or from the state reset to 0 in step 340 described later. At this time, the control further proceeds to step 160, and it is determined whether or not the count value Cf (n) exceeds a predetermined limit value Cfo. If the answer is yes, the control proceeds to step 170 and it is determined that the stroke sensor (or load sensor) for the n-wheel has failed. In contrast, when the answer to step 140 is no, or while the answer to step 160 is no, control bypasses step 170.

  In the following step 180, it is determined whether or not n exceeds 4. While the answer is no, the control returns to step 120, and the same processing is sequentially repeated for the four wheels. When a failure occurs in the stroke sensor (or load sensor) for any of the four wheels, it is determined. Is done.

  In the illustrated embodiment, subsequently, it is determined whether or not puncture has occurred in any of the four wheels. First, control proceeds to step 190, where n is reset again to 0, and n is incremented by 1 each time the following steps 200 to 250 are repeated, and the same processing is performed for four wheels.

  In this case, in the following step 210, it is determined whether or not S (n) calculated above is larger than a certain deviation ΔS2 as compared with Sa (n). This is to detect that the vertical displacement of the wheel increases abnormally when the tire is punctured. The value of the deviation ΔS2 is set to a size suitable for the purpose of such puncture detection. In this case as well, there is a possibility that an erroneous determination may occur if it is determined that the answer of step 210 is once punctured, and that the wheel is punctured. Proceeding to step 220, the number of times is counted as the count value Cp (n) reset to 0 at the start of control or at step 340 described later. When the count value exceeds a certain limit value Cpo set appropriately, the control proceeds to step 240 and it is determined that the n-wheel tire is punctured. When the processing of steps 200 to 250 is completed, the control proceeds to step 260, where n is reset to 0.

  In the illustrated embodiment, subsequently, it is determined whether or not a non-slip chain is attached to the drive wheel. Control proceeds to step 270, and the vehicle is assumed to be a rear wheel drive vehicle. Therefore, in step 270, the wheel vertical direction detected on the left and right rear wheels (n = 3,4) as drive wheels is detected. The sum of the maximum displacement values S (3) and S (4) is calculated as Sdr, and the maximum wheel vertical displacement detected above the left and right front wheels (n = 1, 2) which are non-driven wheels. The sum of the values S (1) and S (2) is calculated as Snd.

  Control then proceeds to step 280, where it is determined whether or not Sdr calculated above is greater than a certain deviation ΔS3 relative to Snd. This is to detect the fact that the vertical displacement of the driving wheel fitted with the anti-slip chain is larger than the vertical displacement of the non-driving wheel not fitted with the non-slip chain. The value of the deviation ΔS3 is set to a size suitable for the purpose of detecting the installation of the anti-slip chain. In this case as well, there is a possibility that an erroneous determination may occur if it is determined that the anti-slip chain is attached to the drive wheel only if the answer to step 280 is once. Each time the control proceeds to step 290, the number of times is counted as the count value Cc reset to 0 at the start of control or at step 340 described later. When this count value exceeds a certain limit value Cco set appropriately, the control proceeds to step 310, and it is determined that a non-slip chain is attached to the drive wheel.

  The count values Cf (n), Cp (n), and Cc continue to be held while the flow is repeated in the above steps, and sometimes Cf (n), Cp (n), or Cc due to misjudgment. When the driving time is prolonged, these values reach Cfo, Cpo, or Cco, and even if there is no failure in the stroke sensor (or load sensor), it is erroneously determined as if there is a failure. Even if there is no puncture, it may be erroneously determined as if the wheel is punctured, or it may be erroneously determined as if the anti-slip chain is not attached to the drive wheel. Therefore, after the completion of steps 270 to 310, the control proceeds to step 320, and the number of processes that have passed through this flow is counted as the count value Ct from the state set at the start of the control or set to 0 in step 340 described later. .

  Next, at step 330, it is determined whether Ct has exceeded a predetermined limit value Cto. Even if Cf (n), Cp (n), or Cc is counted up due to misjudgment, the limit value Cto is Cfo, Cpo, or C0 until the number of processes through this flow reaches Cto. If Cco is not reached, it is assumed that there is no failure in the stroke sensor (or load sensor), there is no puncture on the wheel, and no non-slip chain is attached to the driving wheel. Cf (n), Cp (n), Cc Is a value suitable for once canceling and resetting to zero. If the answer to step 330 is yes, control proceeds to step 340 where Cf (n), Cp (n), and Cc are reset to 0 and Ct is also reset to 0. While the answer to step 330 is no, step 340 is bypassed. Thereafter, the control returns to the start at a predetermined cycle, and the same control is repeated.

  Thus, in the illustrated embodiment, in each flow, it is determined whether or not there is a failure in the stroke sensor (or load sensor) for any wheel, and a puncture occurs in any wheel. The determination as to whether or not the non-slip chain is attached to the drive wheel is performed as a series of processes.

  FIG. 3 is a schematic diagram showing a hardware configuration of a wheel abnormality detection device according to the present invention in which the stroke sensor in FIG. 1 is replaced by a vertical acceleration sensor. Also in this case, it is publicly known to provide a vertical acceleration sensor for each of the four wheels, and therefore the configuration shown in the figure is well known as hardware. As shown, the vertical acceleration of each wheel detected by the vertical acceleration sensor incorporated in each of the left front wheel, right front wheel, left rear wheel, and right rear wheel was configured as one function of the electronic control unit. It supplies to the wheel abnormality detection part by this invention.

  FIG. 4 is a flowchart showing an example of the control performed in the wheel abnormality detection unit in the electronic control unit of FIG. 3 as one embodiment of the present invention. In the flowchart of FIG. 4, steps corresponding to the steps in the flowchart of FIG. 2 are indicated by the same step numbers as in FIG. A redundant description of these corresponding steps is omitted to avoid redundancy of the specification.

  In the flowchart of FIG. 4, in step 35, the vertical acceleration Fs (n, m in the measurement time m for the wheel n is detected by the vertical acceleration sensor (G sensor) provided for each wheel. ) Is detected.

  Next, the control proceeds to step 45, where the vertical acceleration Fs (n, m) detected in the current flow is based on the vertical acceleration Fs (n, m-1) detected in the previous flow. It is determined whether or not it is large. If the answer is yes, control proceeds to step 55 where the current Fs (n, m) is taken as Fs (n). On the other hand, if the answer is no, the control proceeds to step 65, and the previous Fs (n, m-1) is set to Fs (n).

  After repeating m detections for each wheel according to the determinations in steps 70 and 90, in step 105, the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel are vertically moved within a predetermined period. Fst is calculated by adding the maximum acceleration values Fs (1), Fs (2), Fs (3), and Fs (4).

  In step 135, Fsa (n) is calculated by dividing the value obtained by subtracting Fs (n) from Fst by 3. Fsa (n) is an average value of the maximum values of the vertical accelerations of the other three wheels excluding the n wheels.

  Next, control proceeds to step 145, where it is determined whether Fs (n) is smaller than Fsa (n) by a predetermined deviation ΔF1 or more. Here, if ΔF1 is set to an appropriate value, when the answer is yes, the maximum value of the vertical acceleration detected for the n-wheel is the maximum value of the vertical acceleration of the other three wheels excluding the n-wheel. It is remarkably small compared to the average value of, and it can be suspected that an abnormality has occurred in the vertical acceleration sensor for the n-wheel. Also in this case, if it is immediately determined that the vertical acceleration sensor for the n-wheel is abnormal because the answer to step 145 is once, an erroneous determination may occur. Is done. If the answer to step 160 is yes, the control proceeds to step 175 where it is determined that the vertical acceleration sensor for the n-wheel has failed.

  After the above processing is performed for four wheels, in this embodiment, it is subsequently determined whether or not puncture has occurred in any of the four wheels.

  In this case, in step 215, it is determined whether or not Fs (n) is larger than a certain deviation ΔF2 compared to Fsa (n). This is also to detect the fact that the vertical acceleration of the wheel increases abnormally when the tire is punctured, and the value of the deviation ΔF2 is set to a size suitable for the purpose of such puncture detection.

  In this case as well, there is a possibility that erroneous determination will occur if it is determined that the puncture has occurred on the wheel only when the answer to step 215 is once. Therefore, confirmation by steps 220 and 230 is performed, and the count value When Cp (n) exceeds the limit value Cpo, it is determined that the n-wheel tire is punctured.

  Also in this embodiment, it is subsequently determined whether or not a non-slip chain is attached to the drive wheel, assuming that the vehicle is a rear wheel drive vehicle. In step 275, the sum of the maximum values Fs (3) and Fs (4) of the wheel vertical acceleration detected on the left and right rear wheels (n = 3,4) as the driving wheels is calculated as Fsdr. In addition, the sum of the wheel vertical accelerations Fs (1) and Fs (2) for the left and right front wheels (n = 1, 2), which are non-driven wheels, is calculated as Fsnd. It is determined whether or not Fsdr is larger than a certain deviation ΔF3 compared to Fsnd.

  In this case as well, there is a possibility that an erroneous determination may occur if it is determined that the anti-slip chain is attached to the drive wheel only when the answer to step 285 is once. Confirmation is performed.

  FIG. 5 is a flowchart showing another example of the control performed in the wheel abnormality detection unit in the electronic control unit of FIG. 1 as still another embodiment of the present invention. The control according to this flowchart may also be repeated at a cycle of several tens to several hundreds of milliseconds during operation of the vehicle.

  When the control is started, in step 410, the numerical value n for identifying the wheel is reset to 0 at the start of the control, or starting from the state where it was reset to 0 in step 550 of the previous flow, only 1 is started. Incremented. For n = 1, 2, 3, and 4, the left front wheel, right front wheel, left rear wheel, and right rear wheel are designated.

  Control then proceeds to step 420 where the value of vertical displacement S (n, t) at time t for n wheels is detected.

  Next, control proceeds to step 430, where S (n, t) is processed by FFT (Fast Fourier Transformer), whereby the distribution of the vertical displacement values of the n-wheels over a predetermined period is changed to the amplitude P ( Conversion to a distribution of n, f) is performed. Each period is set by a time to in the next step 440. Such processing is performed for each of the four wheels based on the determination in step 450.

  Control then proceeds to step 460, where n is once reset to 0 and control then proceeds to step 470.

  In step 470, a first specific frequency f1 from P (1, f), P (2, f), P (3, f), P (4, f) for each of the four wheels. P (1, f1), P (2, f1), P (3, f1), and P (4, f1), which are the values of P, are added together and the amplitude P is 4 for the specific frequency f1. A ring total value Pf1t is calculated. The first specific frequency f1 is an appropriate frequency for distinguishing the frequency generated in the change in the vertical displacement of the wheel when the wheel is punctured.

  Control then proceeds to step 480 where n starts at 1 and is incremented by 1 each time and the following processing is performed for each wheel.

  In step 490, the value obtained by subtracting P (n, f1) from Pf1t is divided by 3, so that the average value Pf1a (n) of P (n, f1) of the other three wheels excluding the n-wheel is obtained. Calculated.

  Next, control proceeds to step 500, where it is determined whether P (n, f1) is greater than a predetermined deviation ΔPf1 greater than Pf1a (n). This is to detect the fact that the vertical displacement of the wheel increases abnormally when the tire is punctured, and in this case, especially when the frequency f1 is appropriately selected, the wheel puncture due to the tire puncture is detected. An abnormal increase in vertical displacement can be reliably determined without being erroneously determined. The value of the deviation ΔPf1 is set to a size suitable for the purpose of such puncture detection.

  Also in this case, there is a possibility that an erroneous determination may occur if it is determined that a puncture has occurred on the wheel only when the answer to step 500 is once. Therefore, in the flowchart of FIG. 2 or FIG. After confirmation is made in steps 510 and 520 similar to steps 220 and 230, when the control reaches step 530, it is determined that the n-wheel tire is punctured. When the processing in steps 480 to 540 is completed, control proceeds to step 550, where n is reset to 0.

  Also in this embodiment, the control subsequently proceeds to step 560, where it is determined whether the vehicle is a rear-wheel drive vehicle and whether or not a non-slip chain is attached to the drive wheel. Therefore, in step 560, P (1, f), P (2, f), P (3, f), P (4, f) for each of the four wheels calculated above, or P (3, f2), P (4, f2), which are the values of P of the rear wheels (n = 3,4) at the second specific frequency f2 are selected and added to be Pf2dr, Further, P (1, f2) and P (2, f2), which are the values of P of the front wheels (n = 1, 2), are selected and added to obtain Pf2nd. The second specific frequency f2 is an appropriate frequency for distinguishing the frequency generated in the vertical displacement of the wheel when the non-slip chain is attached to the drive wheel.

  Control then proceeds to step 570, where it is determined whether Pf2dr calculated above is greater than a certain deviation ΔPf2 relative to Pf2nd. The deviation ΔPf2 is suitable for the purpose of detecting on the basis of the frequency f2 that the vertical displacement of the driving wheel fitted with the non-slip chain is larger than the vertical displacement of the non-driving wheel not fitted with the non-slip chain. It is made a size. Also in this case, if the answer to step 570 is once “yes” and it is determined that the anti-slip chain is attached to the drive wheel, an erroneous determination may still occur. After the confirmation is made in Steps 580 and 590 similar to Steps 290 and 300 in the flowchart, when the control reaches Step 600, it is determined that the non-slip chain is attached to the driving wheel.

  FIG. 6 is a step showing a modified example in place of steps 560 and 570 in the flowchart of FIG. This is applied to the case where a non-slip chain is attached to both the front wheel and the rear wheel in a four-wheel drive vehicle, and the attachment is determined.

  In this case, in step 562, the frequency of the vertical displacement of the wheel is significantly increased by the attachment of the chain as compared with the case where the chain is not attached. Therefore, such a high third specific frequency f3 is obtained. P (1, f3), P (2, f3), P (3, f3), P (4, f3), which are P values of each wheel, are added together to calculate Pf3t, In step 572, it is determined whether or not Pf3t is equal to or larger than an appropriate limit value Pf3o indicating attachment of the non-slip chain to the drive wheel. By doing so, it is possible to detect the attachment of the chain even when the vehicle is a four-wheel drive vehicle and the chain is attached to all the wheels.

  Also in this case, after execution of the step of determining the attachment of the non-slip chain, steps 610 to 630 similar to steps 320 to 340 in the flowchart of FIG. 2 or FIG. 4 are performed, and counting is performed with an appropriate flow number. The values Cp (n), Cc and Ct are reset.

  FIG. 7 is a flowchart showing another example of the control performed in the wheel abnormality detection unit in the electronic control unit of FIG. 3 as another embodiment of the present invention. In the flowchart of FIG. 7, the steps corresponding to the steps in the flowchart of FIG. 5 are indicated by the same step numbers as in FIG. A redundant description of these corresponding steps is omitted to avoid redundancy of the specification.

  In the flowchart of FIG. 7, in step 425, the vertical acceleration Fs (n, t) at the current time t is determined for the wheel n by the vertical acceleration sensor (G sensor) provided for each wheel. Detected. In step 435, Fs (n, t) is processed by FFT, so that the distribution of the value of the vertical acceleration of the n-wheels over a predetermined period is changed to the distribution of the amplitude Q (n, f) with respect to the frequency. Is converted to

  Also in this case, Q (n, f) is calculated for each of the four wheels based on the determination in step 450, and after resetting n to 0 in step 460, in step 475, For each of the four wheels, Q (1, f), Q (2, f), Q (3, f), Q (4, f) is a value of Q at a fourth specific frequency f4. Q (1, f4), Q (2, f4), Q (3, f4), Q (4, f4) are selected and added to calculate the total value Qf4t of Q for a specific frequency f4 . The fourth specific frequency f4 is an appropriate frequency for distinguishing the frequency generated in the change in the vertical acceleration of the wheel when the tire of the wheel is punctured.

  Next, in step 480, n is incremented by 1 each time starting from 1, and processing is performed for each wheel. In step 495, the value obtained by subtracting Q (n, f4) from Qf4t is set to 3. The average value Qf4a (n) of Q (n, f4) of the other three wheels excluding the n wheels is calculated by dividing by.

  Control then proceeds to step 505, where it is determined whether Q (n, f4) is greater than Qf4a (n) by a predetermined deviation ΔQf4. This is intended to reliably determine the abnormal increase in the vertical acceleration of the wheel when the tire is punctured, in particular, by selecting the frequency f4 at which it can be remarkably confirmed, without erroneously determining it.

  In this case as well, there is a possibility that an erroneous determination may occur if it is determined that a puncture has occurred on the wheel only when the answer to step 505 is once. Therefore, in the flowchart of FIG. 2 or FIG. After confirmation is made in steps 510 and 520 similar to steps 220 and 230, when the control reaches step 530, it is determined that the n-wheel tire is punctured, and when the processing in steps 480 to 540 is completed, the control is performed. Advances to step 550 and n is reset to zero.

  Also in this embodiment, the control subsequently proceeds to step 565, where it is determined whether the vehicle is a rear-wheel drive vehicle and whether or not a non-slip chain is attached to the drive wheel. . Therefore, in step 565, there is a certain value from Q (1, f), Q (2, f), Q (3, f), Q (4, f) for each of the four wheels calculated above. Q (3, f5) and Q (4, f5), which are the Q values of the rear wheels (n = 3,4) at the fifth specific frequency f5, are selected and added to form Qf5dr, and Q (1, f5) and Q (2, f5), which are Q values of the front wheels (n = 1, 2), are selected and added to obtain Qf5nd. The fifth specific frequency f5 is also an appropriate frequency for distinguishing the frequency generated in the change in the vertical acceleration of the wheel when the anti-slip chain is attached to the drive wheel.

  Next, control proceeds to step 575, where it is determined whether or not Qf5dr calculated above is greater than a certain deviation ΔQf5 compared to Qf5nd. The deviation ΔQf5 is suitable for the purpose of detecting on the basis of the frequency f5 that the vertical acceleration of the driving wheel equipped with the non-slip chain is increased compared to the vertical displacement of the non-driving wheel not equipped with the non-slip chain. It is made a size. In this case as well, if the answer to step 575 is once “yes” and it is determined that a non-slip chain is attached to the drive wheel, an erroneous determination may still occur. After the confirmation is made in Steps 580 and 590 similar to Steps 290 and 300 in the flowchart, when the control reaches Step 600, it is determined that the non-slip chain is attached to the driving wheel.

  FIG. 8 is a step showing a modified example in place of steps 565 and 575 in the flowchart of FIG. This is applied to the case where a non-slip chain is attached to both the front wheel and the rear wheel in a four-wheel drive vehicle, and the attachment is determined.

  In this case, in step 567, the frequency of the vertical acceleration of the wheel is significantly increased by the attachment of the chain as compared with the case where the chain is not attached, so that such a high sixth specific frequency f6 is obtained. Q (1, f6), Q (2, f6), Q (3, f6), Q (4, f6), which is the Q value of each wheel, is added and Qf6t is calculated. In step 577, it is determined whether or not Qf6t is equal to or larger than an appropriate limit value Qf6o indicating attachment of the anti-slip chain to the drive wheel. By doing so, it is possible to detect the attachment of the chain even when the vehicle is a four-wheel drive vehicle and the chain is attached to all the wheels.

  While the present invention has been described in detail with respect to several embodiments thereof, it will be apparent to those skilled in the art that various modifications can be made to these embodiments within the scope of the present invention. .

Schematic which shows one hardware structure of the wheel abnormality detection apparatus by this invention. The flowchart which shows an example of the control performed in the wheel abnormality detection part in the electronic controller of FIG. Schematic which shows another one hardware structure of the wheel abnormality detection apparatus by this invention. The flowchart which shows an example of the control performed in the wheel abnormality detection part in the electronic controller of FIG. The flowchart which shows another example of the control performed in the wheel abnormality detection part in the electronic controller of FIG. FIG. 6 is a step showing a modified example instead of steps 560 and 570 in the flowchart of FIG. 5. The flowchart which shows another example of the control performed in the wheel abnormality detection part in the electronic controller of FIG. FIG. 6 is a step showing a modified example in place of steps 565 and 575 in the flowchart of FIG. 5.

Claims (17)

  Using a wheel abnormality detection device for detecting an abnormality occurring in each wheel of a vehicle having four or more wheels with tires, either a vertical displacement of each wheel with respect to the vehicle body or a vertical acceleration of each wheel is time-sequentially The time series change value detected for one wheel is compared with the time series change value detected for a plurality of other wheels, and when the difference exceeds a predetermined limit value, the one wheel A wheel abnormality detection device characterized by determining that the vehicle is abnormal.   The wheel abnormality detection device according to claim 1, wherein the time-series change value is a maximum value of vertical displacement detected for a predetermined number of times or for a predetermined period by predetermined periodic detection for each wheel.   If the maximum value of the vertical displacement of one of the wheels is smaller than the average value of the maximum vertical displacement of other wheels by a predetermined value or more, the stroke sensor of the one wheel is abnormal. The wheel abnormality detection device according to claim 2, wherein the determination is made.   When the maximum value of the vertical displacement of one of the wheels is greater than the average value of the maximum vertical displacement of other wheels by a predetermined value or more, it is determined that the tire of the one wheel is punctured The wheel abnormality detection device according to claim 2.   When the maximum value of the vertical displacement of the driving wheel among the wheels is larger than the maximum value of the vertical displacement of the non-driving wheel by a predetermined value or more, it is determined that the non-slip chain is attached to the driving wheel; The wheel abnormality detection device according to claim 2.   2. The wheel abnormality detection device according to claim 1, wherein the time-series change value is a maximum value of vertical acceleration detected for a predetermined number of times or for a predetermined period by predetermined periodic detection for each wheel.   When the maximum vertical acceleration of one of the wheels is smaller than the average of the maximum vertical acceleration of other wheels by a predetermined value or more, the vertical acceleration sensor of the one wheel is abnormal. The wheel abnormality detection device according to claim 6, wherein it is determined that there is a wheel abnormality.   When the maximum value of the vertical acceleration of one of the wheels is larger than the average value of the maximum vertical acceleration of other wheels by a predetermined value or more, it is determined that the tire of the one wheel is punctured The wheel abnormality detection device according to claim 6.   Determining that a non-slip chain is attached to the driving wheel when the maximum vertical acceleration value of the driving wheel among the wheels is larger than the maximum vertical acceleration value of the non-driving wheel by a predetermined value or more; The wheel abnormality detection device according to claim 6.   The time-series change value is an amplitude with respect to a specific frequency when the distribution of the vertical displacement detected for a predetermined number of times or for a predetermined period by a predetermined periodic detection for each wheel is replaced with a frequency distribution. The wheel abnormality detection device according to 1.   The amplitude with respect to the first specific frequency in the frequency distribution of one of the wheels is a predetermined value than the average value of the amplitude with respect to the first specific frequency in the frequency distribution of other wheels. The wheel abnormality detection device according to claim 10, wherein when it is greater than the above, it is determined that the tire of the one wheel is punctured.   When the amplitude of the driving wheel among the wheels with respect to the second specific frequency in the frequency distribution is larger than the amplitude of the non-driving wheel with respect to the second specific frequency by a predetermined value or more, the driving wheel The wheel abnormality detection device according to claim 10, wherein it is determined that a non-slip chain is attached to the wheel.   When all the wheels are driving wheels and the amplitude of each wheel with respect to the third specific frequency in the frequency distribution is equal to or greater than a predetermined value, it is determined that all the driving wheels are equipped with non-slip chains. The wheel abnormality detection device according to claim 10.   The time-series change value is an amplitude with respect to a specific frequency when the distribution of vertical acceleration detected by a predetermined number of times or a predetermined period of time is replaced with a frequency distribution for each wheel. The wheel abnormality detection device according to 1.   The amplitude with respect to the fourth specific frequency in the frequency distribution of one of the wheels is a predetermined value from the average value of the amplitude with respect to the fourth specific frequency in the frequency distribution of other wheels. The wheel abnormality detection device according to claim 14, wherein when it is larger than the above, it is determined that the tire of the one wheel is punctured.   When the amplitude of the driving wheel among the wheels with respect to the fifth specific frequency in the frequency distribution is larger than the amplitude of the non-driving wheel with respect to the fifth specific frequency by a predetermined value or more, the driving wheel The wheel abnormality detection device according to claim 14, wherein it is determined that a non-slip chain is attached to the wheel. When each of the wheels is a driving wheel and the amplitude of each wheel with respect to the sixth specific frequency in the frequency distribution is equal to or greater than a predetermined value, it is determined that a slip-proof chain is attached to all the driving wheels. The wheel abnormality detection device according to claim 14.

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