JP2015148495A - Abnormality detection device of wheel speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an erroneous detection of abnormality of a wheel speed sensor, by discriminating acceleration occurred by change of a road surface during travelling and acceleration occurred by abnormality of the wheel speed sensor, with an inexpensive and simple structure.SOLUTION: The presence or absence of abnormality of any of the wheel speed sensors 2a to 2d is detected by a determination part 8 based on a determination result of whether correlation exists between a movement periodic pattern when moving a distance equivalent to an outer perimeter of each of wheels 1a to 1d and an acceleration periodic pattern for each of the wheel speed sensors 2a to 2d, for example, the latter period matching with the former period, and the acceleration period pattern for each of the wheel speed sensors 2a to 2d by acceleration calculation parts 4a to 4d. Thereby, the acceleration occurred by change of a road surface during travelling and the acceleration occurred by the abnormality of the wheel speed sensor can be clearly discriminated and the erroneous detection of the abnormality of the wheel speed sensor can be prevented.

Description

  The present invention relates to an abnormality detection device for a wheel speed sensor that detects whether or not an abnormality has occurred in a wheel speed sensor that is provided on a plurality of wheels of a vehicle and outputs a measurement signal corresponding to the rotation of each wheel.

  In general, a wheel speed sensor that is provided on each wheel of an automobile or the like and measures the wheel speed has, for example, a plurality of N-pole and S-pole magnetic poles arranged alternately on the periphery of a disk, and a magnetic resistance in the vicinity of the periphery of the disk. Magnetic detection elements such as elements and hall elements are arranged, and the magnetic change due to the movement of the magnetic pole accompanying the rotation of the wheel is detected by the magnetic detection element, and the magnetic change is output as a pulse signal to the subsequent circuit. Then, the number of pulses per predetermined time is calculated by the subsequent circuit, the rotational speed of the wheel is derived, and the vehicle speed is derived. At this time, acceleration can also be derived by differentiating the derived vehicle speed with respect to time.

  By the way, in such a wheel speed sensor, when an abnormality such as any N pole and / or S pole is detached or damaged, the pulse signal jumps and the period of the magnetic change is disturbed, so that the vehicle speed is accurate. It cannot be derived well. Therefore, conventionally, when an output pulse jump due to an abnormality in the wheel speed sensor occurs, the acceleration that is the time change of the speed is generated by the change of the vehicle speed derived by the subsequent circuit, and the acceleration of a predetermined value or more is generated. It is considered to detect the presence or absence of abnormality of the wheel speed sensor depending on whether or not it continues for a predetermined time (for example, Patent Document 1).

  In addition, one pulse period in the pulse signal period of the wheel speed sensor is set as an intermediate pulse period, and before and after that, the previous and subsequent pulse periods are measured, and the difference between the front and rear pulse periods falls within a predetermined value. It has also been proposed to determine that there is an abnormality in the wheel speed sensor when the value obtained by dividing the pulse period by the preceding and succeeding period pulse periods is equal to or greater than a certain value (for example, Patent Document 2).

JP 2001-116760 A (see paragraph 0002) JP 2001-165948 A (see paragraphs 0010 to 0021 and FIGS. 3 to 5)

  However, according to the method described in Patent Document 1 described above, the wheel speed, that is, the rotational speed of the wheel may change when the vehicle travels, for example, over a convex portion of the road surface, and acceleration may occur at that moment. If the distance between the convex parts formed artificially on the road surface at regular intervals coincides with the outer peripheral length of the wheel, it is caused by the acceleration generated when getting over the convex part of the road surface while driving and the abnormality of the wheel speed sensor Therefore, there is a risk that the acceleration that occurs when the vehicle travels over the convex portion of the road surface is erroneously determined to be due to an abnormality in the wheel speed sensor.

  Further, in the case of the method described in Patent Document 2 described above, complicated processing such as measurement of the intermediate pulse period and the preceding and following pulse periods and the derivation of the difference between the preceding and following pulse periods is required, and the abnormality detection system is expensive. There is a problem of becoming.

  The present invention distinguishes between acceleration caused by road surface change during traveling and acceleration caused by abnormality of the wheel speed sensor, and can prevent erroneous detection of abnormality of the wheel speed sensor with a simple and inexpensive configuration. With the goal.

  In order to achieve the above object, an abnormality detection device for a wheel speed sensor according to the present invention provides an abnormality in a wheel speed sensor that is provided on each of a plurality of wheels of a vehicle and outputs a measurement signal according to the rotation of each wheel. In an abnormality detection device for a wheel speed sensor for detecting whether or not it has occurred, an acceleration deriving means for deriving an acceleration for each of the two wheel speed sensors caused by a change in the measurement signal from each of at least two wheel speed sensors, Determining means for determining whether or not there is a correlation between a movement cycle pattern that moves a distance corresponding to the outer peripheral length of the wheel and an acceleration cycle pattern for each of the wheel speed sensors derived by the acceleration deriving means; and Based on the result of the determination by the means and the acceleration cycle pattern for each of the two wheel speed sensors, whether or not there is an abnormality in the two wheel speed sensors is determined. It is characterized by comprising detecting means for output (claim 1).

  In addition, when the determination unit determines that there is a correlation between the movement cycle pattern and the acceleration cycle pattern for each of the wheel speed sensors, the detection unit determines the acceleration cycle of the wheel speed sensors. If the pattern is the same pattern, the acceleration pattern of both the wheel speed sensors is due to a road surface change, and the acceleration due to a change in the measurement signal of only the acceleration cycle pattern of one of the wheel speed sensors is If derived, it is preferable to detect abnormality of the wheel speed sensor (claim 2).

  Briefly describing the principle of the present invention, when the distance between the convex portions artificially formed on the road surface at regular intervals coincides with the outer peripheral length of the wheel, by traveling on such a road surface, Acceleration occurs at the moment when the rotational speed of the wheel changes when going over the convex part, but as long as there is no abnormality in the wheel speed sensor, the measurement signal from any wheel speed sensor changes in the same way without being disturbed. Any acceleration derived based on the output of the speed sensor changes in the same cycle. Therefore, if the acceleration periodic patterns based on the outputs of at least two wheel speed sensors are the same, it can be determined that the acceleration due to the road surface change has been detected.

  At this time, by determining that the acceleration due to the road surface change has been detected, it is possible to prevent erroneous detection of the acceleration due to the road surface surface abnormality as in the conventional case.

  On the other hand, if any one of the wheel speed sensors has an abnormality such as magnetic pole damage or detachment, the other wheels except for the wheel speed sensor having the abnormality, even if the vehicle is traveling on a flat road at a constant speed Although no disturbance occurs in the output of the speed sensor, only the output of the abnormal wheel speed sensor is disturbed, and the acceleration is derived based on the measurement signal from the abnormal wheel speed sensor. When acceleration is derived based only on the output of one of the speed sensors, it can be determined that the wheel speed sensor is abnormal.

  Therefore, according to the first aspect of the present invention, the movement cycle pattern that moves the distance corresponding to the outer peripheral length of the wheel and the acceleration cycle pattern of the acceleration for each of at least two wheel speed sensors derived by the acceleration deriving means. Based on the determination result by the determination means whether there is a correlation such as the latter period and the former period being in between, and the acceleration period pattern for each wheel speed sensor by the acceleration deriving means Acceleration caused by road surface changes and acceleration caused by wheel speed sensor anomalies can be clearly distinguished, eliminating the need for complicated processing such as period measurement and period difference calculation as in the past With a simple and inexpensive configuration, it is possible to prevent erroneous detection of an abnormality in the wheel speed sensor.

  According to the second aspect of the present invention, between the movement cycle pattern that moves the distance corresponding to the outer peripheral length of the wheel and the acceleration cycle pattern of the acceleration pulse for each wheel speed sensor derived by the acceleration deriving means. When the determination means determines that there is a correlation such that the latter period coincides with the former period, for example, it is determined that the vehicle is traveling on a road surface on which convex portions are formed at the same interval as the outer peripheral length of the wheel. Therefore, it can be determined that the acceleration by the two-wheel speed sensors is caused by the road surface change.

  Therefore, by determining that the acceleration due to the road surface change has been detected, it is possible to prevent erroneous detection of the acceleration due to the road surface surface abnormality as in the conventional case.

  Furthermore, there is no correlation between the movement cycle pattern that moves the distance corresponding to the outer peripheral length of the wheel and the acceleration cycle pattern of the acceleration pulse for each wheel speed sensor derived by the acceleration deriving means, that is, the latter cycle When it is judged by the judging means that the former cycle does not match and there is no correlation, it is running on a flat road, for example, instead of a road surface on which convex portions are formed at the same interval as the wheels described above, At that time, if the acceleration is derived based on the output of only one of the wheel speed sensors by the acceleration deriving means, the abnormality of the wheel speed sensor can be detected. The occurrence can be accurately detected.

It is a block block diagram of one Embodiment of the abnormality detection apparatus of the wheel speed sensor which concerns on this invention. 2 is a timing chart for explaining the operation of FIG. 1. 2 is a timing chart for explaining the operation of FIG. 1.

  An embodiment of the present invention will be described in detail with reference to the block diagram of FIG. 1 and the timing charts of FIGS.

  As shown in FIG. 1, right front wheel speed sensor 2a and left front wheel speed sensor 2b provided on left and right front wheels 1a and 1b, and right rear wheel speed sensor 2c provided on left and right rear wheels 1c and 1d, left Output pulse signals, which are measurement signals from the rear wheel speed sensor 2d, are input to the vehicle speed calculation units 3a, 3b, 3c, and 3d, respectively, and the number of pulses per predetermined time is calculated by each of the vehicle speed calculation units 3a to 3d. The rotational speeds of the wheels 1a to 1d are calculated to calculate the vehicle speed, and the vehicle speeds calculated by the vehicle speed calculation units 3a to 3d by the acceleration calculation units 4a, 4b, 4c, and 4d in the subsequent stages are respectively timed. The acceleration is calculated by differentiation. These acceleration calculation units 4a to 4d correspond to acceleration deriving means in the present invention.

  Then, the accelerations Aa, Ab, Ac, Ad calculated by the respective acceleration calculation units 4a to 4d are respectively input to the comparators 5a, 5b, 5c, 5d and compared to determine whether or not they are equal to or greater than the threshold value Ath. If the accelerations Aa, Ab, Ac, Ad by the arithmetic units 4a-4d are equal to or higher than a preset threshold value Ath, the outputs of the comparators 5a-5d become, for example, high level, and the high levels of the comparators 5a-5d A pulse is input to each of the counters 6a, 6b, 6c, and 6d, and the output duration time of the high-level pulse from each of the comparators 5a to 5d is counted by each counter 6a to 6d.

  Further, whether or not the durations Ta, Tb, Tc, and Td counted by the counters 6a to 6d exceed a reference time Tth (for example, 3 seconds) preset by the subsequent comparators 7a, 7b, 7c, and 7d, respectively. The accelerations Aa, Ab, Ac, Ad by the respective acceleration calculation units 4a to 4d are taken in by the determination unit 8 and the respective acceleration periodic patterns are observed by the determination unit 8 until the reference time Tth is exceeded. .

  By the way, as shown in FIG. 1, period monitors 9a, 9b, 9c, and 9d for outputting reset signals to the counters 6a to 6d are provided, and these acceleration monitors 4a to 4d are derived by these period monitors 9a to 9d. The acceleration cycle of the acceleration to be performed is input, and the movement cycle for moving at a current vehicle speed over a distance corresponding to the known outer peripheral length of each wheel 1a to 1d is input to each cycle monitor 9a to 9d in advance. It is monitored whether or not the movement period and the acceleration period coincide with each other. When the movement periods and the acceleration periods do not coincide with each other, a reset signal is output to each of the counters 6a to 6d to reset the counters 6a to 6d.

  Therefore, when the acceleration cycle coincides with the movement cycle, for example, while traveling on a road surface where convex portions are formed at the same interval as the outer peripheral length of the wheel, the acceleration caused by the road surface change and the acceleration caused by the abnormality of the wheel speed sensor Counters 6a-6d are not reset while accelerations Aa, Ab, Ac, Ad equal to or higher than threshold value Ath continue for reference time Tth or more. The output of the level is continuously output, and during that time, the determination unit 8 observes the acceleration period pattern of the accelerations Aa, Ab, Ac, and Ad, and determines whether or not the acceleration is caused by the road surface change during traveling. Furthermore, an abnormal wheel speed sensor is specified.

  On the other hand, when the movement cycle and the acceleration cycle do not match, it is determined that the vehicle is traveling on a road surface or a flat road having convex portions that are not at the same interval as the outer peripheral length of the wheel, and at that time one of the wheels When the acceleration based on the output of the speed sensor is derived, all other counters corresponding to the wheel speed sensor having no abnormality are reset, and the determination unit 8 determines the subsequent stage of the counter corresponding to the wheel speed sensor from which the acceleration is derived. Only the output of the comparator continues at, for example, a high level. During this high level, the determination unit 8 observes the acceleration cycle pattern, and the determination unit 8 detects the abnormality of the wheel speed sensor.

  Then, the process by the determination part 8 is demonstrated in detail.

  Since the outer peripheral lengths of the wheels 1a to 1d are known and are all the same, the determination unit 8 moves the distance corresponding to the outer peripheral lengths of the wheels 1a to 1d at the current vehicle speed, The determination unit 8 determines whether or not there is a correlation between the acceleration cycle patterns for each of the wheel speed sensors 1a to 1d, for example, the latter acceleration cycle and the former movement cycle match, and it is determined that there is a correlation. In this case, while the outputs of the comparators 7a to 7d are at a high level, for example, the acceleration period patterns of the accelerations Aa to Ad by the acceleration calculation units 4a to 4d input to the determination unit 8 are observed, and all the accelerations are observed. If the period is the same, it is determined that the acceleration based on the outputs of the wheel speed sensors 2a to 2d is due to a change in the road surface.

  And by the determination part 8, a correlation exists between the movement period pattern when moving the distance corresponding to the outer peripheral length of each wheel 2a-2d at the present vehicle speed, and the acceleration period pattern for each wheel speed sensor 2a-2d. Even when it is determined that there is an abnormality in the wheel speed sensor other than the acceleration due to the road surface change, when only one of the acceleration period patterns of the wheel speed sensors 2a to 2d is different from the other acceleration period patterns. Therefore, the wheel speed sensor having a different acceleration cycle pattern is identified as an abnormal wheel speed sensor.

  Further, for example, when traveling on a flat road, the determination unit 8 moves the same distance as the outer peripheral length of each wheel 2a to 2d at the current vehicle speed, and each wheel speed sensor 2a to 2d. When it is determined that there is no correlation with the acceleration cycle pattern, if acceleration is derived based on the output of only one of the wheel speed sensors 2a to 2d among the acceleration calculation units 4a to 4d, The counter corresponding to the wheel speed sensor other than the wheel speed sensor from which the acceleration is derived is reset, the time is counted by the counter corresponding to the wheel speed sensor from which the acceleration is derived, and, for example, a high level output of the comparator at the subsequent stage is output. While continuing, the acceleration period pattern by the said wheel speed sensor will be observed by the determination part 8, and it determines with the said wheel speed sensor being abnormal.

  Such correlation presence / absence determination processing by the determination unit 8 corresponds to the determination unit in the present invention, and abnormality detection processing of the wheel speed sensors 2a to 2d by the determination unit 8 corresponds to the detection unit in the present invention.

  When the acceleration cycle pattern is observed as described above, acceleration is derived at the same cycle based on the outputs of the wheel speed sensors 2a to 2d, and the acceleration cycle patterns of the wheel speed sensors 2a to 2d are shown in FIGS. When it is the same as shown in (d), as described above, there is no abnormality in any of the wheel speed sensors 2a to 2d. For example, a road surface on which convex portions are formed at the same intervals as the outer peripheral lengths of the wheels 1a to 1d. It can be determined that the acceleration generated by traveling is derived.

  At this time, in addition to the acceleration pulse generated by traveling on the road surface on which the convex portions are formed at the same intervals as the outer peripheral lengths of the wheels 1a to 1d, for example, as shown by a broken line in FIG. When an acceleration pulse different from that of the other wheel speed sensors 2b to 2d is derived only in 2a, the acceleration cycle pattern of the wheel speed sensor 2a is different from that of the other wheel speed sensors 2b to 2d. The wheel speed sensor 2a can be identified as an abnormality.

  Further, as shown in FIGS. 3A to 3D, when acceleration is derived based on the output of only the wheel speed sensor 2a and no acceleration is derived from the other wheel speed sensors 2b to 2d, the vehicle travels on a flat road, for example. Since there is a change in the output of any of the wheel speed sensors 2a to 2d and no acceleration should be detected, there is an abnormality that the acceleration is detected only in the wheel speed sensor 2a. It can be detected that an abnormality such as breakage or detachment of the magnetic pole occurs in the speed sensor 2a.

  Therefore, according to the above-mentioned embodiment, each wheel speed sensor 2a-2d derived | led-out by the movement period pattern which moves the distance equivalent to the outer periphery length of each wheel 1a-1d at the present vehicle speed, and the acceleration calculating parts 4a-4d. The road surface changes during traveling based on the determination result of whether or not there is a correlation between the acceleration cycle patterns of the respective accelerations and the acceleration cycle patterns of the wheel speed sensors 2a to 2d by the acceleration calculation units 4a to 4d. And the acceleration caused by the abnormality of the wheel speed sensors 2a to 2d can be clearly distinguished, and there is no need to perform complicated processing such as period measurement and period difference calculation as in the past. With a simple and inexpensive configuration, it is possible to prevent erroneous detection of an abnormality in the wheel speed sensor.

  In addition, since the wheel speed sensor in which an abnormality such as breakage or detachment of the magnetic pole has occurred can be easily identified and detected with an inexpensive configuration, an abnormality detection device can be provided at a low cost.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the case where the determination unit 8 performs the detection process based on the outputs of the four wheel speed sensors 2a to 2d at the same time has been described. However, each wheel speed sensor 2a to 2d is divided into two sets, and Even if such correlation determination processing and abnormality detection processing are performed using only one set of wheel speed sensors, erroneous detection of abnormality of the wheel speed sensors can be prevented.

  Further, the four wheel speed sensors 2a to 2d may be divided into two groups and alternately performed for each group. Furthermore, each wheel speed sensor 2a to 2d is divided into two groups, and a determination unit having the same function as the above-described determination unit 8 is provided for each group, and a correlation determination process is performed by each determination unit for each group. In addition, abnormality detection processing may be performed.

  Further, in the above-described embodiment, when the comparators 5a to 5d, 7a to 7d, and the counters 6a to 6d are provided, and acceleration equal to or greater than a predetermined value (Ath) by the acceleration calculation units 4a to 4d continues for a predetermined time (Tth), Although the case where the abnormality detection processing of the wheel speed sensor is performed has been described, it is not always necessary to provide the comparators 5a to 5d, 7a to 7d, and the counters 6a to 6d, and what is the acceleration derived by the acceleration calculation units 4a to 4d? The acceleration periodic pattern may be observed when the acceleration is derived regardless of the value of the acceleration or the duration of the derivation of the acceleration.

DESCRIPTION OF SYMBOLS 1a-1d ... Wheel 2a-2d ... Wheel speed sensor 4a-4d ... Acceleration calculating part (acceleration deriving means)
8: Determination unit (determination means, detection means)

Claims (2)

In a wheel speed sensor abnormality detection device that detects whether or not an abnormality has occurred in a wheel speed sensor that is provided on each of a plurality of wheels of a vehicle and outputs a measurement signal according to the rotation of each wheel,
Acceleration deriving means for deriving acceleration for each of the wheel speed sensors generated by a change in the measurement signal from each of at least two wheel speed sensors;
Determining means for determining whether or not there is a correlation between a movement period pattern that moves a distance corresponding to the outer peripheral length of the wheel and an acceleration period pattern for each of the wheel speed sensors derived by the acceleration deriving means;
A wheel speed sensor comprising: detection means for detecting any abnormality of the both wheel speed sensors based on a result of the determination by the determination means and the acceleration cycle pattern for each of the both wheel speed sensors. Anomaly detection device. The detection means includes
When the determination means determines that there is a correlation between the movement cycle pattern and the acceleration cycle pattern for each of the wheel speed sensors, if the acceleration cycle patterns of the wheel speed sensors are the same pattern The acceleration pattern of both the wheel speed sensors is due to a road surface change, and if the acceleration is derived by changing the measurement signal of only the acceleration cycle pattern of any one of the wheel speed sensors, the wheel The abnormality detection device for a wheel speed sensor according to claim 1, wherein an abnormality of the speed sensor is detected.

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