JP2001165948A - Abnormality detection method for pulse signal of wheel speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make easily detectable a nick of wheel speed sensor. SOLUTION: In the abnormality detection method of pulse signal of wheel speed sensor, a nick of the wheel is judged by making one pulse period in a pulse period of the pulse signal of a wheel speed sensor as a medium pulse period, measuring the pulse periods in front and back of the pulse, and in the case where the difference of pulse period in the front and back of the pulse is within a specific value and medium pulse period divided by the pulse period in the front and back of the pulse period is a certain value, the existence of a nick of wheel is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detection of a pulse signal from a wheel speed sensor in a vehicle.

[0002]

2. Description of the Related Art Conventionally, there is no logic for detecting a missing tooth of a wheel speed sensor itself, and a rapid change in wheel speed caused by a missing tooth or a falling wheel speed sensor is detected by detecting a change in wheel acceleration. . For example, there is a method of capturing a sudden change in wheel speed that is impossible at each wheel, and determining that a failure represented by tooth missing has occurred when the phenomenon satisfies a certain condition. Was.

In this method, the threshold value for determining the failure has a considerable tolerance in order to prevent erroneous detection. Therefore, even if a few teeth of the sensor ring are missing, it is difficult to grasp the state. Was. Furthermore, when catching the missing tooth of the active sensor, it has been difficult to detect the missing tooth due to the eccentricity or the adhesion of the iron piece peculiar to the active sensor.

[0004]

<A> An object of the present invention is to make it possible to easily detect missing teeth of a wheel speed sensor. <B> An object of the present invention is to make it possible to easily detect the number of missing teeth of a wheel speed sensor.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a vehicle equipped with a wheel speed sensor for measuring the rotational speed of a wheel and an electronic control unit for processing a pulse signal of the wheel speed sensor. One of the pulse periods is defined as the intermediate pulse period, the preceding and following pulse periods are measured, the difference between the preceding and following pulse periods is within a predetermined value, and the intermediate pulse period is divided by the preceding and following pulse periods. Is greater than or equal to a certain value, characterized in that it is determined that there is tooth missing, an abnormality detection method of the pulse signal of the wheel speed sensor, or
In the method of detecting a pulse signal abnormality of the wheel speed sensor, a pulse period adjacent to the intermediate pulse period is set as the next intermediate pulse period, sequentially determining a missing tooth, and detecting the number of missing teeth. In the method of detecting an abnormality of the pulse signal of the wheel speed sensor or the method of detecting the abnormality of the pulse signal of the wheel speed sensor, if the number of missing teeth is measured more than a predetermined number of times at the same missing tooth position, an abnormality occurs in the pulse signal. This is a method for detecting an abnormality of a pulse signal of a wheel speed sensor, characterized in that it is determined that the pulse signal is detected.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

<A> Overview of Vehicle Brake Control A wheel control device for a vehicle, for example, as shown in FIG.
A wheel speed sensor 1 for measuring the rotation speed of the wheel, and a signal from the wheel speed sensor 1 is processed to determine a wheel speed, a wheel acceleration, an estimated vehicle speed, etc., and a wheel brake such as an anti-lock brake control or a braking force distribution control. An arithmetic and control unit 2 for controlling the hydraulic pressure is provided. The arithmetic processing unit 2 also includes a register 21 for the preceding pulse period T0, a register 22 for the intermediate pulse period T1, a register 23 for the subsequent pulse period T2, a register 24 for the average pulse period Ts, and a correction number N indicating the number of missing teeth.
c, a register 26 for the total number of teeth Na, a register 27 for a tooth count value N indicating the current tooth position,
Further, an error counter register 28 is provided.

<B> Wheel Speed Sensor The wheel speed sensor 1 has, as shown in FIG. 1, for example, a sensor ring 11 attached to a rotor and rotating, and a sensor element 12 for measuring the rotation of the sensor ring. The wheel speed sensor 1 has an active sensor and a passive sensor,
The active sensor has a large number of magnets mounted around the sensor ring 11, and a sensor element 12 using a magnetic detection element such as a magnetoresistive element or a Hall element is arranged near the outer periphery of the sensor ring 11. The generated magnetism is detected, and a change in the magnetism is output as an electric signal to detect the rotation speed of the sensor ring 11. The passive sensor includes an electromagnetic induction type sensor element 12 having a magnetic resistance circuit with a gap and a sensor ring 11.
Of the sensor ring 11
When the irregularities around the sensor ring come and go, the magnetoresistive circuit opens and closes, and outputs a change in the opening and closing as an electric signal, and the sensor ring 11
This is to detect the rotation speed of.

<C> Generation of Pulse Signal In FIG. 2, the pulse signals (d), (e), and (f) counted by the arithmetic processing unit 2 are a passive sensor waveform (b) from the sensor element 12 and an active sensor waveform (b). The electric signal of (c) is processed by a waveform shaping circuit (not shown) or the like, and is generated corresponding to the tooth position (a) of the sensor ring 11. In FIG. 2, the pulse signal is generated at both the rising and falling timings of the electric signal from the sensor element 12.

<D> Missing tooth of pulse signal When one tooth of a pulse signal is missing, in FIG. 2 (e), a pulse signal is produced at both rising and falling timings. It becomes one pulse. When two pulse signals are missing, in FIG.
One pulse period is one pulse.

As described above, when the wheel 3 is rotating at a substantially constant speed, the rotation speed of the sensor ring 11 is also constant,
By measuring the period of the pulse signal, it can be seen that the pulse period differs by an odd number (except 1) between the case where there is no tooth missing and the case where there is no tooth missing.

When a pulse signal is produced by one of the rising and falling timings of the electric signal from the sensor element 12, the pulse period is an integral multiple (excluding 1) of the case where there is no tooth chipping and the case where there is no tooth missing. Will be different.

Hereinafter, a method of detecting a pulse signal abnormality will be described.

<A> Acquisition of pulse period Abnormality detection of a pulse signal is carried out by the arithmetic and control unit 2 and FIG.
The active sensor waveform (c) will be described as an example.
Therefore, first, the processing of the number of teeth is started by interruption as shown in FIG. The pulse period T of a certain adjacent pulse signal
0, T1, and T2, and these values are used as the values of the previous pulse period T0.
, The register 22 of the intermediate pulse period T1,
It is stored in the register 23 of the subsequent pulse period T2 (S1).

<B> Judgment of Running State In order to check whether the wheel speed is in an accelerating state or a constant state, the front pulse period T0 and the rear pulse period T2 are compared (S2). The difference D between the preceding pulse period T0 and the following pulse period T2 is obtained. If the difference D is within a predetermined value A, it is determined that the wheel speed has not changed and is in a constant state. On the other hand, if the difference D is equal to or larger than the predetermined value A, it is determined that the wheel speed is accelerating (including deceleration) and fluctuating. Here, the predetermined value A is a value at which the wheel speed is considered to be substantially constant, and is smaller than the pulse period.

<C> Pulse cycle comparison When the wheel speed is constant, pulse cycle comparison for checking for missing teeth is performed (S3). The pulse cycle comparison is shown in the flowchart of FIG. First, in order to check whether or not the intermediate pulse period T1 is missing, an average value (Ts = (T0 + T2) / 2) of the preceding pulse period and the following pulse period, that is, an average pulse period Ts is obtained (S31). Next, the magnitudes of the intermediate pulse period T1 and the average pulse period Ts are compared (S
32). For example, a constant B is set to a certain threshold, and T1 / Ts ≧
Find B. If T1 has one missing tooth, T1 / Ts
Is almost 3, indicating that there is an abnormality. Here, although the average pulse period Ts is obtained, the preceding pulse period T0 and the subsequent pulse period T2 are substantially equal, so that either one of the pulse periods may be used instead of the average pulse period Ts.

If T1 / Ts ≧ B, it is considered that there is a missing tooth, and the number of missing teeth is corrected (S33). In the correction of the number of missing teeth, the number of missing teeth is checked at the same missing tooth position, and the number of missing teeth is stored in the register 25 of the correction number Nc. For example, when T1 / Ts is approximately 3, there is one missing tooth, so 1 is added to the register 25 of the correction number Nc. T1
When / Ts is approximately 5, there are two missing teeth, so 2 is added to the register 25 of the correction number Nc. If T1 / Ts ≧ B does not hold, it is determined that there is no missing tooth.

This process is repeated to determine the number of missing teeth for another part of missing teeth, correct the number of missing teeth, and update the register 25 of the corrected number Nc. In this way, the correction number Nc is obtained for all the teeth.

<D> Tooth Missing Correction Next, a process of tooth missing correction is performed (S4). FIG. 5 shows a flowchart of the tooth missing correction. Therefore, first, the correction number Nc is subtracted from the number of teeth Na to obtain the total number of observed teeth in one round (Na-Nc), and the current tooth signal count value N of the pulse signal is obtained. If there is a missing tooth at the current pulse position, it is checked whether there is a missing tooth in the previously detected pulse signal that has made one revolution (S42).

If the previously detected pulse signal has a missing tooth, 1 is added to the error counter 28 (S4).
3). If there is no missing tooth in the previously detected pulse signal, 0 is added to the error counter 28 (S44).

<E> Time chart of failure determination FIG. 6 shows the above processing in a time chart. When the vehicle speed becomes constant at t0 and tn, measurement of the pulse period is started, and if there is no missing tooth, the measured value of the wheel speed is constant, and if there is missing tooth, the measured value decreases, but , Return immediately. Check the value Ne of the error counter 28,
The count value increases each time a tooth is missing, and when the count value exceeds a failure determination threshold value C, it is determined that a failure has occurred, and a failure determination process is performed.

[0022]

According to the present invention, the following effects can be obtained. <B> It is possible to easily detect a missing tooth of the wheel speed sensor caused by the influence of the eccentricity of the rotor or the adhesion of iron powder. <B> The number of missing teeth of the wheel speed sensor can be easily detected.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a vehicle speed sensor.

FIG. 2 is a waveform diagram of a vehicle speed sensor.

FIG. 3 is a flowchart of main processing for detecting missing teeth;

FIG. 4 is a flowchart of a period comparison process.

FIG. 5 is a flowchart of tooth missing correction processing;

FIG. 6 is an explanatory diagram of tooth missing processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Wheel speed sensor 11 ... Sensor ring 12 ... Sensor element 2 ... Arithmetic controller 21 ... Pre-pulse cycle register 22 ... Intermediate pulse cycle register 23 ... Post-pulse cycle register 24 ... Average pulse Cycle register 25 ··· Number of corrections 26 ··· Number of teeth 27 ··· Count value of teeth 28 ··· Error counter 3 ··· Wheel

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Kamiya 8000 Nakase, Hamakita-shi, Shizuoka Nisshinbo Industries Co., Ltd. F-term in Hamakita Seiki Plant (reference) 3D046 BB01 HH36 KK11 MM06

Claims (3)

[Claims] In a vehicle provided with a wheel speed sensor for measuring a rotation speed of a wheel, and an electronic control unit for processing a pulse signal of the wheel speed sensor, one of pulse cycles of a pulse signal of the wheel speed sensor is included. If the difference between the preceding and following pulse periods falls within a predetermined value, and the value obtained by dividing the intermediate pulse period by the preceding and following pulse periods is equal to or greater than a certain value, the tooth A method for detecting an abnormality in a pulse signal of a wheel speed sensor, comprising determining that there is a chip. 2. The method according to claim 1, wherein a pulse period adjacent to the intermediate pulse period is set as a next intermediate pulse period, and a missing tooth is sequentially determined. A method for detecting an abnormality of a pulse signal of a wheel speed sensor, comprising detecting a number of pulses. 3. The method according to claim 1, wherein if the number of missing teeth is measured a predetermined number of times or more at the same location of the missing tooth, an abnormality occurs in the pulse signal. A method for detecting an abnormality in a pulse signal of a wheel speed sensor.