JPH07306218A - Wheel speed detector and wheel slip controller - Google Patents

Abstract

PURPOSE:To prevent an unexpected control by making such a decision that a noise is generated by the fluctuation in the external field when the magnitude of an output signal from a wheel speed sensor does not exceed a threshold value although the frequency of thereof exceeds a predetermined value. CONSTITUTION:The wheel speed detector for detecting the wheel speed of each wheel comprises wheel speed sensors 26-29 each converting the fluctuation of flux into the voltage signal. A threshold value corresponding to the output value from the sensor is preset when the sensor 26-29 outputs a pulse signal of a specific frequency. When the pulse signal outputted from the sensor 26-29 has a frequency higher than a predetermined value, a decision is made whether the magnitude thereof exceeds the threshold value. Two threshold values are set; one is set slightly lower than a pulse signal output from the sensor having a predetermined frequency in the range of 50-60Hz, for example, and the other is set lower than that. Thereby, whether an output signal represents a noise caused by the fluctuation of external field, can be judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel speed detecting device and a wheel slip control device, and more particularly to a wheel speed detecting device equipped with a so-called electromagnetic pickup type wheel speed sensor,
The present invention also relates to a wheel slip control device including such a wheel speed detection device.

[0002]

2. Description of the Related Art Conventionally, as a wheel speed detecting device for detecting the speed of each wheel in a vehicle such as an automobile, a so-called electromagnetic pickup type which converts a change in magnetic flux into a voltage signal and outputs a pulsed output signal is known. Those equipped with the wheel speed sensor are generally widely used. This type of wheel speed detection device uses the rotation of a gear-shaped (or sawtooth-shaped) rotation detection plate (tooth-shaped rotor) that rotates integrally with the wheel as an electromagnetic pickup (wheel The wheel speed sensor is provided with, for example, a permanent magnet and a coil for voltage generation, and the tooth portion passes in the vicinity of the pickup portion as the rotor rotates. The magnetic flux changes in the voltage generating coil, and the voltage signal is output accordingly. Then, in this case, the voltage signal is output in a pulse shape each time the tooth portion passes in the vicinity of the pickup portion as the tooth-shaped rotor rotates.

The detection data obtained by such a wheel speed detecting device is used for so-called anti-skid control device for preventing the occurrence of a locked or skid state of each wheel during vehicle braking, and for suppressing slippage of driving wheels during vehicle running. In a vehicle equipped with a control device such as a so-called traction control device that can control the slip state of the wheels, it is used as basic input information for performing these controls. That is, in the case of anti-skid control, for example, the acceleration / deceleration of each wheel is calculated based on the wheel speed data obtained by the wheel speed detection device, and the pseudo vehicle body of the vehicle is also estimated based on the wheel speed data. The slip ratio of the wheel can be calculated from the speed and the wheel speed, and the occurrence of wheel lock can be detected by comparing this slip ratio with a preset threshold value. Then, depending on whether or not the wheels are locked, a series of controls for decreasing or increasing the braking force for each wheel is repeatedly executed until the vehicle stops, for example. In the case of traction control,
Basically, the speed difference between the driving wheel and the driven wheel is calculated from the wheel speed data of each wheel, and when the speed difference exceeds a preset threshold value, for example, the power given to the driving wheel such as reducing the engine output. Is controlled or a braking force is applied to the drive wheels.

By the way, since the electromagnetic pickup type wheel speed sensor converts the magnetic flux change into a voltage signal and outputs the signal as described above, when there is a large change in the external magnetic field, this change occurs. May be affected by. That is, a change in the external magnetic field may be input as external noise, which may affect the accuracy and reliability of the detection result. Regarding such a noise problem, for example, JP-A-60-25836 and JP-A-62-255871.
Japanese Patent Laid-Open Publication No. 2005-242242 discloses a method in which the noise determination is performed by comparing the difference between the current calculated value and the previous calculated value of the wheel speed with a reference value. Although not particularly conscious of external noise, for example, in Japanese Patent Laid-Open No. 63-172967, the period of each pulse signal is compared with the previous pulse period to determine an abnormality, and an abnormal pulse period is detected. It is disclosed that the correction is performed based on the relationship with the previous pulse period.

[0005]

A railway vehicle, for example, can be considered as a device that causes a large change in the external magnetic field that can affect the wheel speed detecting device of a moving automobile. That is, the power system of the railway vehicle is driven with a large value of current, and when such a railway vehicle passes near the automobile equipped with the wheel speed detecting device, the external magnetic field of the wheel speed detecting device changes greatly. Is brought about. In this case, in the case of an ordinary railway vehicle, the current supplied to its drive system is direct current, so the change in the external magnetic field does not have periodicity, and there is no particular effect on the detection of wheel speed. Not considered. However, in the case of the Shinkansen, a large current of AC 60 Hz (Hertz) is usually used, and when passing this, a magnetic field change of a cycle of 60 Hz is brought about.

[0006] Therefore, for example, when a road passes over the elevated Shinkansen, and a car stops or runs at a very low speed on this road, when the Shinkansen passes under the road, 60 Hz There is a problem that the AC magnetic field acts on the wheel speed detection device and is superimposed on the detection signal as external noise. In this case, the frequency of noise is constant (60 Hz), but its strength (magnitude) changes depending on the magnitude of the power load of the Shinkansen vehicle. On the other hand, as the electromagnetic pickup type wheel speed detecting device,
A toothed rotor having a number of teeth of 44 is generally widely used, and in the case of this number of teeth, a magnetic field change caused by an alternating current of 60 Hz corresponds to about 9 km / hr in terms of speed. Therefore, the wheel speed detection device outputs a voltage signal on which noise corresponding to the speed of about 9 km / hr is superimposed as the Shinkansen vehicle passes.

In this case, if the traveling speed of the automobile is high to some extent, the original signal level output from the wheel speed sensor is high (the output is high), so even if the above noise is superimposed, the detected value of the wheel speed is Although it is unlikely to exert any influence, the influence of the noise becomes great when the automobile is stopped or traveling at a very low speed. That is, the vehicle itself actually stops traveling (vehicle speed 0 km / hr) or travels at an extremely low vehicle speed, but the wheel speed detection device detects the wheel speed of 9 km / hr as noise.

The intensity (magnitude) of this noise changes depending on the magnitude of the power load of the Shinkansen vehicle as described above. The signal level read by the anti-skid control device is predetermined, and the anti-skid control device reads or does not read the noise signal of 9 km / hr depending on the magnitude relationship between the read signal level and the noise level. In other words, 9km
The noise signal of / hr may or may not be input to the anti-skid controller side. And this 9
If a noise signal of km / hr is input to the anti-skid control device side and then this signal is not input, it is assumed that the wheel speed has been rapidly reduced from 9 km / hr to 0 (zero) km / hr. There is a problem that the driver may feel uncomfortable because the anti-skid control may be performed in an unexpected driving state because the control may start to be executed.

To solve this problem, however, by changing the number of teeth of the tooth profile rotor combined with the wheel speed sensor of the wheel speed detecting device from the normal 44 to, for example, 90, the wheel speed corresponding to AC 60 Hz is obtained. It is conceivable to make a change so as not to affect the execution of the anti-skid control. That is, the antiskid controller is
Generally, if the wheel speed is 5 km / hr or less, it is set not to enter the control, while the number of teeth of the tooth profile rotor is set to 9
When set to 0, AC 60Hz is about 4.5km in terms of speed.
/ Hr, so even if this noise signal is input,
The execution of anti-skid control is never started. However, in this case, it is necessary to fundamentally change the manufacturing process of the above-mentioned tooth profile rotor, including the manufacturing of the die, and there is a problem that the cost is significantly increased.

Further, depending on the direction of the wheel speed sensor attached to each wheel and the direction of the magnetic field generated by passage of the Shinkansen, noise may occur only on the front wheel side or only on the rear wheel side due to changes in the external magnetic field. However, when the traction control device is installed in the vehicle, for example, if the vehicle is of a rear-wheel drive type, if noise is generated only on the rear wheel side, the drive wheel and the driven wheel are affected by this noise. The speed difference between the driver and the vehicle will appear larger than it actually is, and it is conceivable that the traction control will be started if the speed difference exceeds a preset threshold. Since the control is performed, there is a problem that the user feels something strange.

By the way, in the above electromagnetic pickup type wheel speed sensor, when the sensor outputs normally without being affected by external noise, etc., the frequency of the output signal (and therefore the wheel of the wheel concerned) It is known that the speed and the output voltage value are in a proportional relationship. That is, when the wheel speed of the wheel (that is, the rotation speed of the toothed rotor that rotates integrally with the wheel) is correctly detected, and the output signal of the frequency corresponding to this wheel speed is output from the wheel speed sensor. The output value of the wheel speed sensor with respect to the frequency is essentially determined by the proportional relationship between the two. Therefore, when a pulse signal is output from the wheel speed sensor, it is possible to confirm whether or not the output signal is normal by checking the relationship between the frequency and the output voltage value for this output signal. is there.

Therefore, according to the present invention, in the wheel speed detecting device equipped with the electromagnetic pickup type wheel speed sensor, the relationship between the frequency of the output signal and the output value is utilized without causing a significant increase in cost. , Reliably discriminating noise due to changes in the external magnetic field, and in a wheel slip control device equipped with such a wheel speed detection device,
The purpose is to prevent the wheel slip control from being performed by the driver in an unexpected driving state.

[0013]

Therefore, the invention according to claim 1 of the present application (hereinafter referred to as the first invention) converts the magnetic flux change into a voltage signal, and changes the frequency corresponding to the frequency of the magnetic flux change. A wheel speed detection device that includes an electromagnetic pickup type wheel speed sensor that outputs a pulse signal, and detects a wheel speed based on an output signal from the wheel speed sensor,
The threshold value corresponding to the sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency is set in advance,
When the frequency of the output signal from the wheel speed sensor is equal to or higher than the predetermined frequency but the output value does not exceed the threshold value, the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. Is determined.

The invention according to claim 2 of the present application (hereinafter,
The second invention) includes an electromagnetic pickup type wheel speed sensor that converts a magnetic flux change into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the magnetic flux change. In the wheel speed detection device for detecting the wheel speed based on, the reading threshold when reading the output signal from the wheel speed sensor, at least, the sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency If the frequency of the output signal from the wheel speed sensor is equal to or higher than the predetermined frequency, the output value of the first threshold value corresponding to Determines that the output signal that does not exceed the first threshold is noise due to a change in the external magnetic field, and reads only the output signal whose output value exceeds the first threshold. It was done.

The invention according to claim 3 of the present application (hereinafter,
In a third invention), in the first or second invention, after the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field, the wheel speed sensor is kept for a certain period of time or more. When a pulse signal whose frequency is equal to or higher than the predetermined frequency is output from the output signal and the output value exceeds the threshold value corresponding to the sensor output value when the pulse signal having the predetermined frequency is output, the noise determination is canceled. It is characterized by being done.

Furthermore, the invention according to claim 4 of the present application.
(Hereinafter, referred to as a fourth invention) is, in the first or second invention, after the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, the wheel speed sensor outputs a predetermined signal. When a pulse signal corresponding to a speed equal to or higher than the wheel speed is output for a certain period of time or longer, the noise determination is canceled.

Furthermore, the invention according to claim 5 of the present application.
In the first or second invention, the wheel speed sensor is attached to each of four wheels of the vehicle, and output signals from the wheel speed sensors are external magnetic fields. After it is determined that there is noise due to the change of the above, the noise determination is canceled when the wheel speed sensors of all the four wheels continue to be in a pulseless state for a certain period of time or longer.

Furthermore, the invention according to claim 6 of the present application.
(Hereinafter, referred to as a sixth invention) is the same as any one of the first to fifth inventions, wherein the predetermined frequency is 50 to 60 Hz.
The frequency is within the range of.

The invention according to claim 7 of the present application (hereinafter,
According to a seventh invention), a wheel speed is detected based on an output signal from an electromagnetic pickup type wheel speed sensor which converts a magnetic flux change into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the magnetic flux change. A wheel speed detecting device, a hydraulic pressure adjusting means for adjusting the braking pressure of each wheel, and a braking pressure of each wheel by operating the hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting device. In a wheel slip control device having an anti-skid control means that increases and decreases dynamically, a threshold value corresponding to a sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency is preset, and the wheel When the frequency of the output signal from the speed sensor is equal to or higher than the predetermined frequency but the output value does not exceed the threshold value, the wheel speed sensor The output signal from is determined to be noise due to a change in the external magnetic field.

Furthermore, the invention according to claim 8 of the present application (hereinafter,
According to an eighth invention), the wheel speed is detected based on an output signal from an electromagnetic pickup type wheel speed sensor which converts a magnetic flux change into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the magnetic flux change. A wheel speed detecting device, a hydraulic pressure adjusting means for adjusting the braking pressure of each wheel, and a braking pressure of each wheel by operating the hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting device. In a wheel slip control device including an anti-skid control unit that increases and decreases dynamically, a reading threshold at the time of reading an output signal from the wheel speed sensor is at least the wheel speed sensor outputs a pulse signal of a predetermined frequency. A plurality of values including a first threshold value corresponding to the sensor output value at the time and a second threshold value smaller by a predetermined amount than the first threshold value are set. When the frequency of the output signal is equal to or higher than the predetermined frequency, the output signal whose output value does not exceed the first threshold value is determined to be noise due to the change of the external magnetic field, and the output value is the first value. Only the output signal that exceeds the threshold value is read.

Further, the invention according to claim 9 of the present application
(Hereinafter, referred to as a ninth invention), in the seventh or eighth invention, after the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field, When a pulse signal whose frequency is equal to or higher than the predetermined frequency is output from the wheel speed sensor and the output value exceeds a threshold value corresponding to the sensor output value when the pulse signal having the predetermined frequency is output, the noise The feature is that the determination is canceled.

Further, the invention according to claim 10 of the present application
(Hereinafter, referred to as a tenth invention), in the seventh or eighth invention, after the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, a predetermined speed is determined from the wheel speed sensor. When a pulse signal corresponding to the wheel speed of the above is output for a certain period of time or more,
The feature is that the noise determination is canceled.

Furthermore, the invention according to claim 11 of the present application.
In the seventh or eighth invention, the wheel speed sensor is attached to each of the four wheels of the vehicle, and output signals from the wheel speed sensors are external magnetic fields. After it is determined that the noise is caused by the change of the above, the noise determination is canceled when the wheel speed sensors of all the four wheels continue to be in the pulseless state for a certain period of time or more.

The invention according to claim 12 of the present application
(Hereinafter, referred to as a twelfth invention), in any one of the seventh to eleventh inventions, the predetermined frequency is 50 to 60.
The frequency is within the range of Hz.

The invention according to claim 13 of the present application (hereinafter referred to as the thirteenth invention) is the wheel slip control device according to any one of the seventh to twelfth inventions. When it is determined that the output signal from the wheel speed sensor is noise due to the change in the external magnetic field when estimating the pseudo vehicle body speed of the vehicle based on the wheel speed detected by the device, this noise determination During the period, the increase in the estimated value of the pseudo vehicle body speed is limited.

Further, an invention according to claim 14 of the present application (hereinafter, referred to as a fourteenth invention) is the wheel slip control device according to any one of the seventh to twelfth inventions, wherein the wheel speed control device detects the wheel speed. When it is determined that the output signal from the wheel speed sensor is noise due to the change in the external magnetic field when estimating the pseudo vehicle body speed of the vehicle based on the wheel speed detected by the device, this noise determination During the period, the pseudo vehicle body speed is estimated to be on the side of 0 km / hr.

Further, the invention according to claim 15 of the present application
(Hereinafter, referred to as a fifteenth invention) is the wheel slip control device according to any one of the seventh to twelfth inventions, wherein an output signal from the wheel speed sensor is noise due to a change in an external magnetic field. If it is determined that the minimum value of the wheel speed for performing the anti-skid control is increased by a predetermined amount during the noise determination period.

Further, the invention according to claim 16 of the present application
(Hereinafter, referred to as 16th invention) In any one of the 7th to 12th inventions, in the slip control device for the wheel, an output signal from the wheel speed sensor is noise due to a change in an external magnetic field. If it is determined that during the noise determination period, the control threshold value for starting the anti-skid control is changed to the side that is hard to enter the control.

The invention according to claim 17 of the present application
(Hereinafter, referred to as a seventeenth invention). In any one of the seventh to twelfth inventions, in the slip control device for a wheel, an output signal from the wheel speed sensor is noise due to a change in an external magnetic field. When it is determined that the anti-skid control is started during the noise determination period, the start of the anti-skid control is prohibited.

The invention according to claim 18 of the present application (hereinafter referred to as the eighteenth invention) is an electromagnetic pickup which converts a magnetic flux change into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the magnetic flux change. Wheel speed detection device for detecting the wheel speed based on the output signal from the wheel speed sensor of the formula, and calculates the speed difference between the drive wheel and the driven wheel based on the wheel speed detected by the wheel speed detection device, When the calculated value exceeds a predetermined value, in a wheel slip control device including traction control means for performing at least one of control for applying a braking force to the drive wheels and control for reducing the engine output, A threshold value corresponding to a sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency is preset, and an output signal from the wheel speed sensor is set. When the output value does not exceed the threshold value even if the frequency is equal to or higher than the predetermined frequency, the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field. is there.

Further, the invention according to claim 19 of the present application (hereinafter referred to as the nineteenth invention) is an electromagnetic pickup which converts a magnetic flux change into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the magnetic flux change. Wheel speed detection device for detecting the wheel speed based on the output signal from the wheel speed sensor of the formula, and calculates the speed difference between the drive wheel and the driven wheel based on the wheel speed detected by the wheel speed detection device, When the calculated value exceeds a predetermined value, in a wheel slip control device including traction control means for performing at least one of control for applying a braking force to the drive wheels and control for reducing the engine output, The reading threshold when reading the output signal from the wheel speed sensor is at least a sensor when the wheel speed sensor outputs a pulse signal of a predetermined frequency. A plurality of first threshold values corresponding to force values and second threshold values smaller by a predetermined amount than these are set, and when the frequency of the output signal from the wheel speed sensor is equal to or higher than the predetermined frequency, The output value is the above first
An output signal that does not exceed the threshold value is determined to be noise due to a change in the external magnetic field, and only the output signal whose output value exceeds the first threshold value is read.

Further, the invention according to claim 20 of the present application
(Hereinafter, referred to as 20th invention) is the 18th or 1st above.
In the invention of claim 9, after it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field, a pulse signal having a frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor for a certain period of time or more. Further, when the output value exceeds a threshold value corresponding to the sensor output value when the pulse signal of the predetermined frequency is output, the noise determination is canceled.

Further, the invention according to claim 21 of the present application
(Hereinafter, referred to as 21st invention) is the 18th or 1st above.
In the ninth invention, after it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field, a pulse signal corresponding to a speed equal to or higher than a predetermined wheel speed is output from the wheel speed sensor for a certain period of time or more. The feature is that the noise determination is canceled when the noise is output.

Further, the invention according to claim 22 of the present application
(Hereinafter, referred to as 22nd invention) is the above 18th or 1st invention.
In the invention of claim 9, the wheel speed sensors are attached to each of the four wheels of the vehicle, and after it is determined that the output signals from the wheel speed sensors are noise due to a change in the external magnetic field, When the wheel speed sensor of No. 2 continues to be in the non-pulse state for a certain period of time or more, the noise determination is canceled.

Furthermore, the invention according to claim 23 of the present application
(Hereinafter, referred to as 23rd invention), in any one of the 18th to 22nd inventions, the predetermined frequency is 50 to 6
The frequency is within the range of 0 Hz.

The invention according to claim 24 of the present application (hereinafter referred to as the twenty-fourth invention) is the wheel slip sensor according to any one of the eighteenth to twenty-third inventions. When it is determined that the output signal from is noise due to the change of the external magnetic field, at least the control for applying the braking force to the driving wheels is prohibited during the noise determination period. is there.

Furthermore, the invention according to claim 25 of the present application (hereinafter referred to as the 25th invention) is an electromagnetic pickup which converts a magnetic flux change into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the magnetic flux change. Wheel speed detection device for detecting the wheel speed based on the output signal from the wheel speed sensor of the formula, and calculates the speed difference between the drive wheel and the driven wheel based on the wheel speed detected by the wheel speed detection device, When the calculated value exceeds a predetermined value, in a wheel slip control device including traction control means for performing at least one of control for applying a braking force to the drive wheels and control for reducing the engine output, If the frequency of the output signal from the wheel speed sensor for the drive wheels does not change even after performing the traction control, the output signal from the wheel speed sensor is output to the outside. It is determined to be the noise due to the change of the field, for during this noise determination period is obtained so as to prohibit the execution of the traction control.

[0038]

According to the wheel speed detecting device of the first invention of the present application, the output signal is output from the outside by utilizing the relationship between the frequency and the output value of the output signal from the wheel speed sensor. It is possible to determine whether or not the noise is due to a change in the magnetic field. That is, in the electromagnetic pickup type wheel speed sensor, when there is no external noise and normal output is performed, the frequency of the output signal and the output voltage value are in a proportional relationship, and the output value is low with respect to the frequency. When this proportional relationship is not established, it can be determined that the output signal is noise. Therefore, when the threshold value corresponding to the sensor output value when the wheel speed sensor outputs the pulse signal of the predetermined frequency is set in advance, and the pulse signal of the frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor. Moreover, by checking whether or not the output value exceeds the threshold value, it is possible to easily determine whether or not the output signal from the wheel speed sensor is noise due to a change in the external magnetic field.

Further, according to the wheel speed detecting device of the second invention of the present application, the output signal is an external magnetic field by utilizing the relationship between the frequency and the output value of the output signal from the wheel speed sensor. When it is determined whether the noise is caused by a change and the output signal is read, only the normally output output signal can be read except for the noise that is determined to be the noise. That is, in the electromagnetic pickup type wheel speed sensor, when there is no external noise and normal output is performed, the frequency of the output signal and the output voltage value are in a proportional relationship, and the output value is low with respect to the frequency. When this proportional relationship is not established, it can be determined that the output signal is noise. Therefore, the threshold value corresponding to the sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency
(1st threshold value) is set in advance, and when the wheel speed sensor outputs a pulse signal having a frequency equal to or higher than the predetermined frequency, it is confirmed whether or not the output value exceeds the first threshold value. It is possible to easily determine whether or not the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. Then, by reading only the output signal whose output value exceeds the first threshold value, it is possible to read only the output signal that is normally output, excluding those that are determined to be noise. Moreover, in this case, a plurality of read threshold values are set including the first threshold value and a threshold value (second threshold value) smaller by a predetermined amount than the first threshold value, so that the output signal from the wheel speed sensor has a low frequency, for example. If the output signal is low (low output), it is determined whether or not the output signal from the wheel speed sensor is noise under various conditions such as switching the reading threshold and using the second threshold described above. It is possible to read only the output signals that have been normally output, excluding those that are determined to be present.

Furthermore, according to the wheel speed detecting device of the third invention of the present application, basically the same effect as that of the first or second invention can be obtained. Moreover, the noise determination may be canceled according to the output state of the pulse signal from the wheel speed sensor after it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. You can That is, a pulse signal whose frequency is equal to or higher than the predetermined frequency is output from the wheel speed sensor over a certain period of time, and the output value is a threshold value corresponding to the sensor output value when the pulse signal having the predetermined frequency is output. When it exceeds, it is considered that the output signal is not noise, and in such a case, the noise determination may be canceled. As a result, accurate noise determination can be canceled.

Further, according to the wheel speed detecting device of the fourth invention of the present application, basically, the same effect as that of the first or second invention can be obtained. Moreover,
Moreover, the noise determination can be canceled according to the output state of the pulse signal from the wheel speed sensor after the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field. . That is, when the rotation speed of the wheel is higher than a certain level, the original signal level output from the wheel speed sensor is high (the output is large), so even if noise is superimposed, the detected value of the wheel speed is substantially reduced. There is no problem even if the noise determination is canceled when the pulse signal corresponding to such a high wheel speed is output for a certain time or more without any influence. Therefore, by setting the predetermined wheel speed to an appropriate value of the height at which the corresponding pulse signal is not substantially affected by noise due to changes in the external magnetic field, it is possible to release the accurate noise determination. It can be carried out.

Further, according to the wheel speed detecting device of the fifth invention of the present application, basically, the same effect as that of the first or second invention can be obtained. Moreover,
Moreover, the noise determination can be canceled according to the output state of the pulse signal from the wheel speed sensor after the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field. . That is, when the wheel speed sensor continues to be in the pulseless state for a certain period of time or more, it is considered that there is no noise. In such a case, the noise determination may be canceled. In particular, when the wheel speed sensors are attached to each of the four wheels of the vehicle, and when the wheel speed sensors of all four wheels continue to be in a pulse-free state for a certain period of time or more, the noise determination is performed. Since it is canceled, more accurate noise cancellation can be performed.

Further, according to the wheel speed detecting device of the sixth invention of the present application, basically, the same effect as that of any one of the first to fifth inventions can be obtained.
In particular, since the above-mentioned predetermined frequency is set to a frequency within the range of 50 to 60 Hz, normally, when a high current of 60 Hz alternating current passes through a Shinkansen vehicle used for its drive system, an external force accompanying the passage of this Shinkansen vehicle is generated. Noise due to changes in the magnetic field can be reliably identified. The above-mentioned frequency range of 50 to 60 Hz is due to the fact that a frequency error is expected with respect to 60 Hz which is normally used in Shinkansen.

According to the wheel slip control device of the seventh aspect of the present invention, the output signal is output from the external magnetic field by utilizing the relationship between the frequency and the output value of the output signal from the wheel speed sensor. It is possible to determine whether or not the noise is due to the change of. That is, in the electromagnetic pickup type wheel speed sensor, when there is no external noise and normal output is performed, the frequency of the output signal and the output voltage value are in a proportional relationship, and the output value is low with respect to the frequency. When this proportional relationship is not established, it can be determined that the output signal is noise. Therefore, when the threshold value corresponding to the sensor output value when the wheel speed sensor outputs the pulse signal of the predetermined frequency is set in advance, and the pulse signal of the frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor. Moreover, by checking whether or not the output value exceeds the threshold value, it is possible to easily determine whether or not the output signal from the wheel speed sensor is noise due to a change in the external magnetic field.

Further, according to the wheel slip control device of the eighth invention of the present application, by utilizing the relationship between the frequency and the output value of the output signal from the wheel speed sensor, the output signal is an external magnetic field. When it is determined whether or not the output signal is noise due to the change, the only output signal that is normally output can be read except for the output signal that is determined to be noise. That is, in the electromagnetic pickup type wheel speed sensor, when there is no external noise and normal output is performed, the frequency of the output signal and the output voltage value are in a proportional relationship, and the output value is low with respect to the frequency. When this proportional relationship is not established, it can be determined that the output signal is noise. Therefore, a threshold value (first threshold value) corresponding to the sensor output value when the wheel speed sensor outputs the pulse signal of the predetermined frequency is set in advance, and the pulse signal of the frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor. Is output, by checking whether the output value exceeds the first threshold value, it is possible to easily determine whether the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. be able to. And the output value is the first
By reading only the output signals that exceed the threshold value, it is possible to read only the output signals that are normally output, excluding those that are determined to be noise. Moreover, in this case, a plurality of read threshold values are set including the first threshold value and a threshold value (second threshold value) smaller by a predetermined amount than the first threshold value, so that the output signal from the wheel speed sensor has a low frequency, for example. If the output signal is low (low output), it is determined whether or not the output signal from the wheel speed sensor is noise under various conditions such as switching the reading threshold and using the second threshold described above. It is possible to read only the output signals that have been normally output, excluding those that are determined to be present.

Further, according to the slip control device for a wheel of the ninth invention of the present application, basically, the same effect as that of the seventh or eighth invention can be obtained. Moreover, the noise determination may be canceled according to the output state of the pulse signal from the wheel speed sensor after it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. You can That is, a pulse signal whose frequency is equal to or higher than the predetermined frequency is output from the wheel speed sensor over a certain period of time, and the output value is a threshold value corresponding to the sensor output value when the pulse signal having the predetermined frequency is output. When it exceeds, it is considered that the output signal is not noise, and in such a case, the noise determination may be canceled. As a result, accurate noise determination can be canceled.

Further, according to the slip control device for a wheel of the tenth invention of the present application, basically, the seventh slip control device described above is used.
Alternatively, the same effect as the eighth invention can be obtained.
Moreover, the noise determination may be canceled according to the output state of the pulse signal from the wheel speed sensor after it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. You can That is, when the rotation speed of the wheel is higher than a certain level, the original signal level output from the wheel speed sensor is high (the output is large), so even if noise is superimposed, the detected value of the wheel speed is substantially reduced. There is no problem even if the noise determination is canceled when the pulse signal corresponding to such a high wheel speed is output for a certain time or more without any influence. Therefore, by setting the predetermined wheel speed to an appropriate value of the height at which the corresponding pulse signal is not substantially affected by noise due to changes in the external magnetic field, it is possible to release the accurate noise determination. It can be carried out.

Furthermore, according to the wheel slip control device of the eleventh invention of the present application, basically, the seventh slip control device described above is used.
Alternatively, the same effect as the eighth invention can be obtained.
Moreover, the noise determination may be canceled according to the output state of the pulse signal from the wheel speed sensor after it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. You can That is, when the wheel speed sensor continues to be in the pulseless state for a certain period of time or more, it is considered that there is no noise. In such a case, the noise determination may be canceled. And
In particular, in the case where the wheel speed sensors are attached to each of the four wheels of the vehicle, when the wheel speed sensors of all the four wheels continue to be in a pulseless state for a certain period of time or more, the noise determination is canceled. Since this is done, more accurate noise cancellation can be performed.

Furthermore, according to the wheel slip control device of the twelfth invention of the present application, basically, the seventh slip control device described above is used.
~ The same effect as any one of the 11th invention can be produced. In particular, since the above-mentioned predetermined frequency is set to a frequency within the range of 50 to 60 Hz, normally, when a high current of 60 Hz alternating current passes through a Shinkansen vehicle used for its drive system, an external magnetic field accompanying the passage of this Shinkansen vehicle is generated. It is possible to reliably discriminate the noise due to the change of. The above-mentioned frequency range of 50 to 60 Hz is due to the fact that a frequency error is expected with respect to 60 Hz which is normally used in Shinkansen.

Further, according to the slip control device for a wheel of the thirteenth invention of the present application, basically, the seventh to first aspects described above are performed.
The same effect as any one of the inventions of 2 can be produced. Moreover, when estimating the pseudo vehicle body speed of the vehicle based on the wheel speed detected by the wheel speed detection device, it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. In this case, since the increase in the estimated value of the pseudo vehicle body speed is limited during the noise determination period, the maximum value of the four wheel speeds is generally set during the noise determination period. It is possible to prevent the given pseudo vehicle body speed from being higher than the actual value due to the influence of noise, and it is possible to prevent the anti-skid control from being executed in an unexpected driving state of the driver. That is, it is possible to avoid the influence of noise due to a change in the external magnetic field without causing a large increase in cost as in the case of changing the number of teeth of the tooth profile rotor of the wheel speed detecting device.

Furthermore, according to the slip control device for a wheel of the fourteenth aspect of the present invention, basically, the seventh to first aspects are
The same effect as any one of the inventions of 2 can be produced. Moreover, when estimating the pseudo vehicle body speed of the vehicle based on the wheel speed detected by the wheel speed detection device, it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. If this is the case, the pseudo vehicle body speed is set to 0 during the noise determination period.
Since it is estimated on the km / hr side, during the noise determination period, the pseudo vehicle body speed that is generally given as the highest value among the four wheel speeds is affected by noise and becomes higher than the actual value. This can be reliably prevented, and the anti-skid control can be prevented from being executed in an unexpected driving state of the driver. That is, it is possible to reliably avoid the influence of noise due to a change in the external magnetic field without causing a large increase in cost as in the case of changing the number of teeth of the tooth profile rotor of the wheel speed detecting device.

Further, according to the wheel slip control device of the fifteenth invention of the present application, basically, the seventh slip control device described above is used.
~ The same effect as any one of the twelfth invention can be obtained. Moreover, when the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field, the wheel speed for performing the anti-skid control is changed during the noise determination period. Since the minimum value is increased by the predetermined amount, it is difficult to enter the antiskid control during the noise determination period, and it is possible to prevent the antiskid control from being executed in an unexpected driving state of the driver. That is, it is possible to avoid the influence of noise due to a change in the external magnetic field without causing a large increase in cost as in the case of changing the number of teeth of the tooth profile rotor of the wheel speed detecting device.

Furthermore, according to the slip control device for a wheel of the sixteenth invention of the present application, basically, the seventh slip control device described above is used.
~ The same effect as any one of the twelfth invention can be obtained. Moreover, when the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field, the control threshold for starting the anti-skid control during the noise determination period. Since it was changed to the side that is hard to enter the control, it becomes difficult to enter the anti-skid control during the above noise determination period,
It is possible to prevent the driver from executing the anti-skid control in an unexpected driving state. That is, it is possible to avoid the influence of noise due to a change in the external magnetic field without causing a large increase in cost as in the case of changing the number of teeth of the tooth profile rotor of the wheel speed detecting device.

Furthermore, according to the wheel slip control device of the seventeenth invention of the present application, basically, the seventh slip control device described above is used.
~ The same effect as any one of the twelfth invention can be obtained. Moreover, when the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field, the start of the anti-skid control is prohibited during the noise determination period. Therefore, during the noise determination period, it is possible to prevent the driver from executing the anti-skid control in an unexpected driving state.
That is, it is possible to reliably avoid the influence of noise due to a change in the external magnetic field without causing a large increase in cost as in the case of changing the number of teeth of the tooth profile rotor of the wheel speed detecting device.

According to the wheel slip control device of the eighteenth invention of the present application, the output signal is output from the external magnetic field by utilizing the relationship between the frequency and the output value of the output signal from the wheel speed sensor. It is possible to determine whether or not the noise is due to the change of. That is, in the electromagnetic pickup type wheel speed sensor, when there is no external noise and normal output is performed, the frequency of the output signal and the output voltage value are in a proportional relationship, and the output value is low with respect to the frequency. When this proportional relationship is not established, it can be determined that the output signal is noise. Therefore, when the threshold value corresponding to the sensor output value when the wheel speed sensor outputs the pulse signal of the predetermined frequency is set in advance, and the pulse signal of the frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor. Moreover, by checking whether or not the output value exceeds the threshold value, it is possible to easily determine whether or not the output signal from the wheel speed sensor is noise due to a change in the external magnetic field.

Furthermore, according to the slip control device for a wheel in accordance with the nineteenth aspect of the present invention, the output signal is output from the external magnetic field by utilizing the relationship between the frequency and the output value of the output signal from the wheel speed sensor. When it is determined whether or not the output signal is noise due to the change, the only output signal that is normally output can be read except for the output signal that is determined to be noise. That is, in the electromagnetic pickup type wheel speed sensor, when there is no external noise and normal output is performed, the frequency of the output signal and the output voltage value are in a proportional relationship, and the output value is low with respect to the frequency. When this proportional relationship is not established, it can be determined that the output signal is noise. Therefore, a threshold value (first threshold value) corresponding to the sensor output value when the wheel speed sensor outputs the pulse signal of the predetermined frequency is set in advance, and the pulse signal of the frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor. Is output, by checking whether the output value exceeds the first threshold value, it is possible to easily determine whether the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. be able to. Then, by reading only the output signal whose output value exceeds the first threshold value, it is possible to read only the output signal that is normally output, excluding those that are determined to be noise. Moreover, in this case, a plurality of read threshold values are set including the first threshold value and a threshold value (second threshold value) smaller by a predetermined amount than the first threshold value, so that the output signal from the wheel speed sensor has a low frequency, for example. If the output signal is low (low output), it is determined whether or not the output signal from the wheel speed sensor is noise under various conditions such as switching the reading threshold and using the second threshold described above. It is possible to read only the output signals that have been normally output, excluding those that are determined to be present.

Further, according to the slip control device for a wheel of the twentieth invention of the present application, basically, the first slip control device described above is used.
The same effect as that of the eighth or nineteenth invention can be obtained. Moreover, the noise determination may be canceled according to the output state of the pulse signal from the wheel speed sensor after it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. You can That is, a pulse signal having a frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor over a certain period of time,
And, when the output value exceeds the threshold value corresponding to the sensor output value when outputting the pulse signal of the predetermined frequency,
It is considered that the output signal is not noise, and in such a case, the noise determination may be canceled. As a result, accurate noise determination can be canceled.

Furthermore, according to the slip control device for a wheel of the twenty-first invention of the present application, basically, the first slip control device described above is used.
The same effect as that of the eighth or nineteenth invention can be obtained. Moreover, since the wheel speed detection device is provided, the output signal of the wheel speed sensor is in the output state of the pulse signal from the wheel speed sensor after it is determined that the output signal is noise due to the change of the external magnetic field. Accordingly, the noise determination can be canceled. That is, when the rotation speed of the wheel is higher than a certain level, the original signal level output from the wheel speed sensor is high (the output is large),
Even if noise is superimposed, it does not substantially affect the detected value of the wheel speed, and when the pulse signal corresponding to such high wheel speed is output for a certain period of time or more, the noise judgment is canceled. There is no problem. Therefore, by setting the predetermined wheel speed to an appropriate value of the height at which the corresponding pulse signal is not substantially affected by noise due to changes in the external magnetic field, it is possible to release the accurate noise determination. It can be carried out.

Further, according to the slip control device for a wheel of the twenty-second invention of the present application, basically, the first slip control device described above is used.
The same effect as that of the eighth or nineteenth invention can be obtained. Moreover, since the wheel speed detection device is provided, the output signal of the wheel speed sensor is in the output state of the pulse signal from the wheel speed sensor after it is determined that the output signal is noise due to the change of the external magnetic field. Accordingly, the noise determination can be canceled. That is, when the wheel speed sensor continues to be in the pulseless state for a certain period of time or more, it is considered that there is no noise. In such a case, the noise determination may be canceled. In particular, when the wheel speed sensors are attached to each of the four wheels of the vehicle, and when the wheel speed sensors of all four wheels continue to be in a pulse-free state for a certain period of time or more, the noise determination is performed. Since it is canceled, more accurate noise cancellation can be performed.

Further, according to the slip control device for a wheel of the twenty-third invention of the present application, basically, the first slip control device described above is used.
The same effect as that of any one of the eighth to twenty-second aspects can be obtained. In particular, since the above-mentioned predetermined frequency is set to a frequency within the range of 50 to 60 Hz, normally, when a high current of 60 Hz alternating current passes through a Shinkansen vehicle used for its drive system, an external magnetic field accompanying the passage of this Shinkansen vehicle is generated. It is possible to reliably discriminate the noise due to the change of. The above-mentioned frequency range of 50 to 60 Hz is due to the fact that a frequency error is expected with respect to 60 Hz which is normally used in Shinkansen.

According to the slip control device for a wheel of the twenty-fourth invention of the present application, basically, the same effect as that of any one of the eighteenth to twenty-third inventions can be obtained. Moreover, when it is determined that the output signal from the wheel speed sensor is noise due to the change in the external magnetic field, at least the control for applying the braking force to the driving wheels is performed during the noise determination period. Since the prohibition is performed, it is possible to prevent the driving wheels from being braked by the traction control in an unexpected driving state during the noise determination period. That is, it is possible to reliably avoid the influence of noise due to a change in the external magnetic field without causing a large increase in cost as in the case of changing the number of teeth of the tooth profile rotor of the wheel speed detecting device.

Further, according to the slip control device of the twenty-fifth aspect of the present invention, when the frequency of the output signal from the wheel speed sensor of the drive wheels does not change even if the traction control is performed, the wheel speed is changed. The output signal from the sensor is determined to be noise due to the change of the external magnetic field, and the execution of the traction control is prohibited during this noise determination period, so the driver does not expect during the noise determination period. It is possible to prevent the driving wheels from being braked by the traction control in the driving state. That is,
As in the case where the number of teeth of the tooth profile rotor of the wheel speed detecting device is changed, the influence of noise due to the change of the external magnetic field can be reliably avoided without causing a large increase in cost.

[0063]

Embodiments of the present invention will be described below as a so-called anti-skid control device (hereinafter referred to as AB
A case where the present invention is applied to a wheel speed detection device and an ABS control device mounted on an automobile equipped with an S control device) will be described with reference to the accompanying drawings. Figure 1
[FIG. 3] is a plan view schematically showing an overall configuration of a vehicle braking system of an automobile according to the present embodiment. As shown in this figure, in the above vehicle, the left and right front wheels 1 and 2 are driven wheels, and the left and right rear wheels 3 and
4 is a rear-wheel drive type drive wheel, and the output torque of the engine 5 is from the automatic transmission 6 through the propeller shaft 7, the differential device 8 and the left and right drive shafts 9 and 10
It is adapted to be transmitted to the left and right rear wheels 3 and 4. The front wheels 1 and 2 and the rear wheels 3 and 4 have disks 11a to 14a that rotate integrally with the wheels 1 to 4 and a caliper 11b that receives the supply of braking pressure to brake the rotation of the disks 11a to 14a. .., 14b, etc. are provided respectively, and these braking devices 11-14 are operated by a brake control system described below.

The above-described vehicle brake control system includes a booster device 17 for increasing the stepping force of the brake pedal 16 by a driver, and a master cylinder for generating a braking pressure according to the stepping force increased by the booster device 17. 18
It has and. The front wheel braking pressure supply line 19 led from the master cylinder 18 is branched into two paths, and the left and right front wheel branch braking pressure lines 19a and 19b respectively provided in these branches are provided in the left and right front wheels 1 and 2. The brake devices 11 and 12 are connected to the calipers 11b and 12b, respectively. The left front wheel branch braking pressure line 19a leading to the brake device 11 for the left front wheel 1 is provided with an electromagnetic opening / closing valve 20a and an electromagnetic relief valve 20b.
A valve unit 20 is installed. Also, the right front wheel 2
In the same way as the first valve unit 20, a second valve unit 21 having an electromagnetic opening / closing valve 21a and an electromagnetic relief valve 21b is also installed in the right front wheel branch braking pressure line 19b leading to the brake device 12 of FIG. Has been done.

On the other hand, the rear wheel braking pressure supply line 22 led from the master cylinder 18 is connected to the first and second brake wheels.
Electromagnetic on-off valve 23a similar to valve units 20 and 21
A third valve unit 23 including an electromagnetic relief valve 23b and an electromagnetic relief valve 23b is installed. The rear wheel braking pressure supply line 22 is branched into two paths downstream of the third valve unit 23. The left and right rear wheel branch braking pressure lines 22a and 22b, which are respectively provided by branching the left and right rear wheels 3,
Calipers 13b, 1 of the braking devices 13, 14 in FIG.
4b are connected respectively. That is, in the brake control system in the present embodiment, the brake device 1 for the left front wheel 1 is operated by the operation of the first valve unit 20.
A first channel for variably controlling the braking pressure of No. 1 and a second channel for variably controlling the braking pressure of the braking device 12 at the right front wheel 2 by the operation of the second valve unit 21;
By the operation of the third valve unit 23, the left and right rear wheels 3,
4 and a third channel for variably controlling the braking pressure of both brake devices 13, 14 are provided.
The channels are controlled independently of each other.

The brake control system is provided with an electronically controlled control unit (hereinafter referred to as ECU) 24 for controlling the first to third channels, respectively. This ECU 24 uses the brake pedal 16
The brake signal from the brake switch 25 that detects ON / OFF of the wheel and the wheel speed signals from the wheel speed sensors 26 to 29 that detect the rotation speeds of the respective wheels are input,
By outputting braking pressure control signals corresponding to these signals to the first to third valve units 20, 21, 23, respectively, braking control for slippage of the left and right front wheels 1, 2 and rear wheels 3, 4, that is, ABS The control is performed in parallel for each of the first to third channels. In the present embodiment, as the wheel speed sensors 26 to 29, so-called detailed description will be given later, so-called so-called conversion of a magnetic flux change into a voltage signal and outputting a pulse signal having a frequency corresponding to the frequency of the magnetic flux change. An electromagnetic pickup type is used, and a wheel speed detecting device for detecting the wheel speeds of the wheels 1 to 4 based on the output signals from the wheel speed sensors 26 to 29 is provided.

The ECU 24 uses the wheel speed sensors 2
Based on the wheel speeds indicated by the wheel speed signals from 6 to 29, the on-off valves 20a, 21a, 23a and the relief valves 20b, 21b, 23b in the first to third valve units 20, 21, 23 are controlled by duty control. By controlling the opening / closing, the braking force is applied to the front wheels 1 and 2 and the rear wheels 3 and 4 with the braking pressure according to the slip state of each wheel 1 to 4. In addition, the first to third valve units 20, 21, 2
The brake oil discharged from the relief valves 20b, 21b, 23b in No. 3 is returned to the reservoir tank 18a of the master cylinder 18 via a drain line (not shown).

In the ABS non-controlled state, no braking pressure control signal is output from the ECU 24, and therefore, as shown in FIG.
~ Relief valves 20b, 21b, 23b of the third valve units 20, 21, 23 are closed and held, and the opening / closing valves 20a, 21a, 23 of the valve units 20, 21, 23 are closed.
Each a will be held open. That is, the braking pressure generated in the master cylinder 18 according to the stepping force of the brake pedal 16 is passed through the front wheel braking pressure supply line 19 and the rear wheel braking pressure supply line 22 to the left and right front wheels 1, 2 and the rear wheels 3. , 4 are supplied to the brake devices 11 to 14, and the braking force corresponding to these braking pressures is applied to the front wheels 1 and 2.
Also, it is directly applied to the rear wheels 3 and 4.

Next, an outline of the brake control performed by the ECU 24 will be described. That is, the ECU 24 calculates the acceleration and deceleration for each wheel based on the wheel speeds indicated by the signals from the wheel speed sensors 26 to 29. Here, the calculation method of the acceleration or deceleration will be explained.
The CU 24 divides the difference between the previous value of the wheel speed and the previous value by the predetermined sampling period Δt (for example, 7 ms), and then updates the value obtained by converting the result to the gravitational acceleration as the current acceleration or deceleration. Then, the ECU 24
The rear wheels 3 and 4 representing the wheel speed and acceleration / deceleration for the third channel are selected. In the present embodiment, more preferably, both wheel speeds W3 and W4 are taken into consideration in consideration of the detection error of the both wheel speed sensors 28 and 29 of the rear wheels 3 and 4 at the time of slip.
The smaller one of the wheel speeds is selected as the rear wheel speed Wr, and the acceleration and deceleration obtained from this wheel speed Wr are used as the rear wheel deceleration and the rear wheel acceleration.

Further, the ECU 24 estimates the pseudo vehicle body speed Vr and the road surface friction coefficient of the vehicle. Of these, the pseudo vehicle body speed Vr is specifically obtained as follows. That is, the ECU 24 selects the highest wheel speed Wmx from the wheel speeds W1 to W4 indicated by the signals from the wheel speed sensors 26 to 29.
Then, the maximum wheel speed Wmx is set to the pseudo vehicle speed Vr.
To be adopted as. At that time, when the wheel speeds W3 and W4 indicated by the signals from the wheel speed sensors 28 and 29 provided on the rear wheels 3 and 4 which are the driving wheels are used as the maximum wheel speed Wmx, the rear wheels 3 and 4 are used. The wheel speeds W3, W2 are higher than the wheel speeds W1, W2 indicated by signals from the wheel speed sensors 26, 27 provided on the front wheels 1, 2 which are the driven wheels due to slipping of
When W4 shows a large value, one of the wheel speeds W1, W2 of the front wheels 1, 2 is adopted as the pseudo vehicle body speed Vr.

On the other hand, when both the front wheels 1 and 2 and the rear wheels 3 and 4 are locked, as shown in Table 1 below, a table preset corresponding to the friction coefficient value MU is referred to,
Assuming a change amount (hereinafter, referred to as a vehicle body speed change amount) ΔVr of the pseudo vehicle body speed Vr per unit time at that time, the pseudo vehicle body speed Vr is decreased according to the vehicle body speed change amount ΔVr.

[0072]

[Table 1]

That is, as will be described later, when the friction coefficient value MU indicating the road surface friction coefficient estimated based on the pseudo vehicle body speed Vr is set to 1 indicating a low μ road surface, the vehicle body speed change amount ΔVr changes. Low-0.3G (value converted to gravitational acceleration) is selected, while the above friction coefficient value MU
Is set to 3 indicating a high μ road surface, -1.2G, which has a large amount of change in vehicle speed change ΔVr, is selected. When the friction coefficient value MU is set to 2 which is an intermediate state between the high μ road surface and the low μ road surface, the vehicle speed change amount ΔVr is set to −0.8 G which is an intermediate value between the two.
Is selected. In this way, the pseudo vehicle body speed Vr of the vehicle is sampled in accordance with the wheel speeds W1 to W4.
It will be updated every time. In the present embodiment, as will be described later in detail, when estimating the pseudo vehicle body speed Vr,
When it is determined that the output signals from the wheel speed sensors 26 to 29 are noise due to a change in the external magnetic field, the increase in the estimated value Vr of the pseudo vehicle body speed is limited during the noise determination period. It is like this.

On the other hand, the road surface friction coefficient is specifically obtained as follows. That is, the ECU 24 calculates the vehicle body speed change amount ΔVr from the pseudo vehicle body speed Vr estimated as described above, and, as shown in Table 2 below, indicates the friction coefficient value set in advance according to the vehicle body speed change amount. The above-mentioned vehicle speed change amount ΔVr is applied to the table and a corresponding value is set as the friction coefficient value MU.

[0075]

[Table 2]

Here, the table of the friction coefficient value MU is set in three stages according to the vehicle body speed change amount ΔVr. For example, the vehicle body speed change amount ΔVr converted into gravitational acceleration is -0.3G. Also has a large value, that is, when the change is small, the friction coefficient value MU indicates a low μ road surface 1
Is selected. On the other hand, when the vehicle body speed change amount ΔVr is a value smaller than -1.2 G, that is, when the change is large,
As the friction coefficient value MU, 3 indicating a high μ road surface is selected.
When the vehicle body speed change amount ΔVr indicates an intermediate value between the two values, 2 indicating a medium friction road surface is selected as the friction coefficient value MU.

The ECU 24 uses the wheel speed sensors 28, 2
The first to third wheel speeds Wr and W2 of the left and right front wheels 1 and 2 and the pseudo vehicle body speed Vr indicated by the signals from the wheel speed sensors 26 and 27, respectively. The slip rate for each channel is calculated. At that time, the slip rate is calculated using the following relational expression. Slip rate = (wheel speed / pseudo vehicle speed) × 100 ... That is, the greater the deviation of the wheel speed from the pseudo vehicle speed, the smaller the slip rate, and the greater the tendency of slipping of the wheel. Subsequently, the ECU 24 executes the above first to third
Set various control thresholds used for channel control.

Here, an outline of the control threshold setting process will be described. The control threshold setting process for the first channel is performed as follows, for example. That is, the ECU 24 selects a control threshold value corresponding to the friction coefficient value and the pseudo vehicle body speed from various control threshold values set in advance according to the vehicle speed range and the road surface friction coefficient. As these control threshold values, for example, the 0-2 deceleration threshold value B02 for determining the transition from the phase 0 indicating the ABS non-control state to the phase 2 indicating the holding state after the pressure increase, and the phase 1 indicating the pressure increase state from the above 1-2 deceleration threshold B for determination of transition to phase 2
12, 2-3 deceleration threshold value B23 for determination of transition from phase 2 to phase 3 indicating depressurized state, 3-5 deceleration for transition determination from phase 3 to phase 5 indicating retained state after depressurization Threshold value B35, 5-1 slip rate threshold value Bsz for judging pressure increase from phase 5 to phase 1, and initial slip rate threshold value B for the first cycle immediately after control start
i and the like are set in accordance with the vehicle speed range and the road surface friction coefficient.

In this case, the deceleration threshold value which greatly affects the braking force is the braking performance when the road surface friction coefficient is large,
In order to achieve a high level of control responsiveness when the road surface friction coefficient is small, it is more preferably set to approach 0G as the level of the friction coefficient value becomes smaller, that is, as the road surface friction coefficient becomes smaller. Further, control thresholds are similarly set for the second and third channels. Then, the ECU 24 performs the lock determination process for each channel and the first to third valve units 2 described above.
Phase determination processing for defining the control amount for 0, 21, and 23 is performed.

The lock determination process will be described below. For example, in the lock determination process for the first channel for the left front wheel,
The ECU 24 first determines the continuation flag Fc for the first channel.
The current value of is set as the previous value, and then the pseudo vehicle body speed Vr and the wheel speed W1 are set under predetermined conditions (for example, Vr <5 km
/ H, W1 <7.5 km / h) is determined, and when these conditions are satisfied, the continuation flag Fc and the lock flag Fl1 are reset to 0, respectively, and if they are not satisfied, the log flag It is determined whether or not Fl1 is set to 1. If the lock flag Fl1 is not set to 1, the lock flag F is set under a predetermined condition (for example, when the pseudo vehicle body speed Vr is higher than the wheel speed W1).
Set 1 to l1. On the other hand, when the ECU 24 determines that the lock flag Fl1 is set to 1, for example, when the phase value P1 of the first channel is set to 5 indicating phase 5, and the slip ratio S1 is larger than 90%, for example. The continuation flag Fc is set to 1. The lock determination process is similarly performed for the second and third channels.

Further, to explain the outline of the phase determination processing, the ECU 24 compares the control thresholds set according to the operating state of the vehicle with the wheel acceleration / deceleration and the slip ratio to determine the ABS non-controlled state. Phase 0 shown, Phase 1 showing a pressure increasing state during ABS control, Phase 2 showing a holding state after pressure increasing, Phase 3 showing a pressure reducing state, Phase 4 showing a sudden pressure reducing state and phase showing a holding state after pressure reducing 5 is selected. Then, the ECU 24 sets a control amount according to the phase value set for each channel, and then sends a braking pressure control signal according to the control amount to the first to third valve units 2.
It outputs to 0, 21, and 23, respectively. This allows
The braking pressures of the front wheel branch braking pressure lines 19a, 19b and the rear wheel branch braking pressure lines 22a, 22b on the downstream side of the first to third valve units 20, 21, 23 are increased or decreased, or increased. Or, it is kept at the pressure level after decompression.

The braking pressure control process in the brake control system is performed as follows according to the flow chart of FIG. 2, for example, taking the first channel as an example. That is, the ECU 24 executes step S1.
At step S2, various data are fetched, and then step S2 is executed to judge whether or not the value of the ABS flag Fa is set to 1. That is, it is determined whether or not ABS control is in progress. The ABS flag Fa is set to 1 when any one of the lock flags Fl1, Fl2, Fl3 of the first to third channels is set to 1, and the brake switch 25 is switched from ON to OFF. It is a flag that is cleared to 0 when it is hit. ECU
24 indicates that the ABS flag Fa is 1 in step S2.
If it is determined to be set to step S3,
Then, it is determined whether the road surface friction coefficient is high μ or not. In this embodiment, it is determined to be YES when the friction coefficient value MU is set to 3 indicating the high μ road surface, and is determined to be NO when the friction coefficient value MU is set to 2 or 1 other than that. Has become.

When the ECU 24 determines in step S3 that the road surface friction coefficient is not high μ, step S4 is executed and the wheel speed W1 of the left front wheel 1 indicated by the signal from the wheel speed sensor 26 is the first set value V1. (Eg 3.5k
m / h), and when it is determined that the wheel speed W1 is greater than the first set value V1, the process proceeds to step S5, where it is determined whether the ABS control is completed. When it is determined that the control is not completed, step S6 is executed and the normal ABS control is executed according to a predetermined subroutine. On the other hand, when the ECU 24 determines in step S4 that the wheel speed W1 is not greater than the first set value V1, the ECU 24 proceeds to step S7, sets a predetermined slow pressure increase control amount, and then executes step S8. Then, the lock flag Fl1 and the continuation flag Fc are each cleared to 0.

When the ECU 24 determines in step S3 that the road surface friction coefficient is high μ,
In step S9, the wheel speed W1 is the first set value V1.
It is determined whether or not the wheel speed W1 is higher than the second set value V2 (for example, 5 km / h) set on the higher wheel speed side. In this case as well, if the wheel speed W1 is larger than the second set value V2. If it is determined, the process proceeds to step S5 to determine whether or not the ABS control is completed. If it is determined that the ABS control is not completed, step S6 is executed and the normal ABS control is executed according to a predetermined subroutine. It is like this. On the other hand, when the ECU 24 determines in step S9 that the wheel speed W1 is not greater than the second set value V2, the ECU 24 executes step S10 to set a predetermined normal pressure increase control amount, and in this case as well. Step S8 is executed to execute the lock flag Fl1 and the continuation flag Fc.
To 0 respectively.

Next, the ABS control in the brake control system will be described by taking the case of the first channel as an example. That is, in the ABS non-controlled state during deceleration, the braking pressure generated in the master cylinder 18 is gradually increased by the depression operation of the brake pedal 16, and, for example, as shown in FIG. 3 (d), the wheel speed W1 of the left front wheel 1 is increased. When the amount of change in (i.e., the wheel deceleration DW1) reaches -3G, the lock flag Fl1 in the first channel is set to 1 and simultaneously the ABS flag Fa is set, as shown in FIGS. Is also set to 1, and from that point A
It will shift to BS control.

The ECU 24 then determines the slip ratio S1, the deceleration DW1, and the acceleration AW calculated from the wheel speed W1.
1 and the above-mentioned various control threshold values are compared. In this case, assuming that the initial slip ratio threshold B1 is set to, for example, 90%, when the slip ratio S1 indicates, for example, 96%, the ECU 24 indicates the phase value P as shown in FIG.
Change 1 from 0 to 2. Therefore, the braking pressure is
As shown in (f), it will be maintained at the level immediately after the pressure increase. Thereafter, for example, when the slip ratio S1 falls below 90%, the ECU 24 sets the phase value P1 to 2
Change from 3 to 3. As a result, the first valve unit 2
The relief valve 20b of 0 becomes O according to the predetermined duty ratio.
N / OFF, the braking pressure is reduced according to a predetermined gradient and the braking force is gradually reduced, and the rotational force of the front wheels 1 is restored accordingly, as indicated by reference numeral (a) in the figure. start.

When the deceleration DW1 and the acceleration AW1 obtained from the wheel speed W1 of the front wheels 1 become 0 respectively after further reduction of the braking pressure, the ECU 24 changes the phase value P1 from 3 to 5. Therefore, the reference numeral (a) in the figure
As shown by, the braking pressure is maintained at the level after the pressure reduction. When the state of phase 5 continues and the slip ratio S1 exceeds 90%, the ECU 24
As shown in (c), the continuation flag Fc is set to 1. As a result, the ABS control on the first channel shifts from the first cycle immediately after the start of control to the second cycle. In that case, the ECU 24 determines that the phase value P1
Is forced to change to 1.

Immediately after the shift to the phase 1, the opening / closing valve 20b of the first valve unit 20 is set in accordance with the initial rapid pressure increase time Tpz set based on the duration of the phase 5 in the first cycle. The valve is opened / closed at a duty ratio of 100%, and the braking pressure is steeply increased, as indicated by the symbol (c) in the figure. After the initial rapid pressure increase time Tpz ends, the on-off valve 20a is turned on / off in accordance with a predetermined duty ratio, and the braking pressure has a gentler gradient than the above-mentioned gradient, as indicated by symbol (d) in the figure. Will gradually rise. When the ECU 24 determines that the slip ratio S1 is larger than the 5-1 slip ratio threshold Bsz in the phase 5 state in the second cycle, the ECU 24 sets the phase value P1 to 1 and shifts to the third cycle.

Then, when the friction coefficient value MU is set to 1 indicating the low μ road surface, when the wheel speed W1 is reduced to the first set value V1 as indicated by the reference numeral (e) in FIG. , The ECU 24 clears the lock flag Fl1 and the continuation flag Fc in the first channel to 0, respectively, as shown in (a) and (b) of FIG. At that time, since the friction coefficient value MU is set to 1 indicating the low μ road surface as described above, the ECU 24 more preferably sets the slow pressure increase control amount and outputs the braking pressure control signal corresponding thereto. Output to the first valve unit 20. As a result, the braking pressure gradually increases as indicated by the symbol (F), and the locked or skid state of the left front wheel 1 is avoided. Immediately before the vehicle stops, the braking pressure control as described above is similarly performed for the second and third channels, so that the left and right front wheels 1, 2 and the rear wheels 3, 4 are locked. Moreover, the occurrence of the skid state is prevented, and the vehicle can be stably stopped even on a low μ road surface such as an ice burn.

On the other hand, the friction coefficient value MU is 3 indicating a high μ road surface.
When the wheel speed W1 is reduced to the second set value V2 this time, as shown by the symbol (g) in FIG. ), The lock flag Fl on the first channel
The 1 and the continuation flag Fc are each cleared to 0, and the process is shifted to the end process from that point. This allows
Compared with the case where the ABS control is continued until the wheel speed W1 drops to the first set value V1, the probability that the braking pressure is unexpectedly reduced is reduced, and the driver does not feel an unnecessarily idling feeling. . Moreover, since the front wheels 1 reliably grip the road surface, the front wheels 1 are not locked or skid, and the running stability is not impaired. Further, the ECU 24 sets the normal pressure increase control amount when the wheel speed W1 decreases to the second set value T2, and outputs a braking pressure control signal corresponding thereto to the first valve unit 20. So the sign
As indicated by (h), the braking pressure rises more quickly than when the μ is low, and the vehicle is surely stopped.

By the way, in the present embodiment, as the wheel speed detecting device for detecting the wheel speed of each of the wheels 1 to 4, as described above, the magnetic flux change is converted into the voltage signal and the pulsed output signal is outputted. A so-called electromagnetic pickup type wheel speed sensor 26-29 is used. That is, for example, taking the one for the front left wheel 26 as an example, as shown in FIG. 6, the wheel speed sensor 26 includes a permanent magnet 26b and a coil 26c for voltage generation, and the pickup section 26a thereof is The gear-shaped (or sawtooth-shaped) tooth-shaped rotor 31 that rotates integrally with the wheel 1 is mounted so as to be located near the outer peripheral portion. In this example,
As the tooth profile rotor 31, one having 44 teeth is used. Then, when the tooth profile rotor 31 rotates as the wheel 1 rotates, the tooth portions 31a, ..., 31a of the tooth profile rotor 31 pass near the pickup 26a, so that a change in magnetic flux occurs in the voltage generating coil 26c. Occurs,
According to this, the voltage signal is output.
In this case, the voltage signal is output in pulses each time the tooth portions 31a, ..., 31a pass near the pickup portion 26a as the tooth-shaped rotor 31 rotates.

The electromagnetic pickup type wheel speed sensor 2
As described above, 6 to 29 are for converting the magnetic flux change into a voltage signal and outputting the signal, so that when there is a large change in the external magnetic field, it is affected by this magnetic field change and the output signal is noisy. May be superimposed, or noise may appear as an output signal when the wheel speed is actually 0 km / hr and there is no output. Specifically, as described above, when the Shinkansen passes through the vicinity of the above-mentioned automobile, when the Shinkansen normally passes a current of a large value of 60 Hz alternating current when it passes, Is 60H
A magnetic field change of z cycles will result. In this case, if the traveling speed of the vehicle is high to some extent, as shown in FIG. 7, the original signal level Vp output from the wheel speed sensors 26 to 29 is high (the output is large), and therefore the noise Vn (in FIG. 7) is generated. Even if (dotted line) is superimposed, it is unlikely that it will affect the detected value of the wheel speed, but when the car is stopped or running at a very low speed, The influence of the noise Vn becomes so great.

In the wheel speed detecting apparatus according to the present embodiment, the tooth-shaped rotor 31 having 44 teeth is used. In the case of this number of teeth, the magnetic field change caused by the AC 60 Hz is about 9 km / hour in terms of speed. Equivalent to hr. Therefore, the wheel speed detection device outputs a voltage signal on which noise corresponding to the speed of about 9 km / hr is superimposed as the Shinkansen passes. That is, the car itself actually stops running
Although the vehicle travels only at a vehicle speed of 0 km / hr or at an extremely low vehicle speed, the wheel speed detection device detects a wheel speed on which a value of 9 km / hr is superimposed as noise.

The strength (magnitude) of this noise is, for example, as shown in FIG.
As shown in, the signal level Va (see the alternate long and short dash line in FIG. 8) read by the ABS control device changes depending on the magnitude of the power load of the Shinkansen vehicle, and the read signal level and the noise level are The anti-skid control device reads or does not read the noise signal Vn of 9 km / hr depending on the magnitude relationship of the above.
That is, the noise signal Vn of 9 km / hr may or may not be input to the anti-skid control device side. Then, when this noise signal Vn of 9 km / hr is input to the anti-skid control device side and then this signal is not input, the wheel speed is rapidly decelerated from 9 km / hr to 0 (zero) km / hr. As a result, execution of anti-skid control may be started.

In this embodiment, when there is a change in the external magnetic field, the change in the magnetic field affects the wheel speed sensors 26 to 29, and noise is superimposed on the output signal, or there is no actual output. If noise appears as an output signal in, the noise can be reliably identified and
Only the output signals that are normally output are read except for those that are determined to be noise, and the ABS control device is designed to prevent the control from starting in an operating state where it does not originally operate. There is. That is, in the present embodiment, as shown in, for example, FIG.
As the reading threshold when reading the output signal from 29, it corresponds to the sensor output value when the wheel speed sensors 26 to 29 output the pulse signal of the predetermined frequency within the range of 50 to 60 Hz, and is more than this sensor output value. A threshold value Sa (hereinafter referred to as a first threshold value) set slightly lower by a certain amount, and a sensor output value when a pulse signal corresponding to a wheel speed of, for example, 2 to 3 km / hr, which is smaller than the threshold value by a predetermined amount, is output. Corresponding to the sensor output value and a threshold value Sb (hereinafter, referred to as a second threshold value) which is set to be slightly lower than the sensor output value.

The above two reading threshold values Sa and Sb are such that the frequency of the output signals from the wheel speed sensors 26 to 29 is 50 to 6 respectively.
If the frequency is equal to or higher than the predetermined frequency within the range of 0 Hz, the first
The threshold value Sa is used, and the output signal whose output value does not exceed the first threshold value Sa is determined to be noise and is not read.
Only those that exceed the threshold value Sa are read as normally output output signals. Further, when a pulse signal having a frequency lower than the predetermined frequency is input, the reading threshold value is switched to the second threshold value Sb, except for those which are determined to be noise without exceeding the second threshold value Sb. , Only the normally output output signal (exceeding the second threshold value Sb) is read.

That is, in the electromagnetic pickup type wheel speed sensors 26 to 29, when there is no external noise and normal output is performed, the frequency of the output signal and the output voltage value are in a proportional relationship, and the frequency is proportional to the frequency. When the output value is low and this proportional relationship is not established, it can be determined that the output signal is noise. Therefore, the wheel speed sensor 26
~ 29 preset the threshold value corresponding to the sensor output value when outputting a pulse signal of a specific frequency, when the pulse signal of the specific frequency or more is output from the wheel speed sensor 26-29, By checking whether or not the output value exceeds the threshold value, it is possible to easily determine whether or not the output signal is noise due to a change in the external magnetic field. Then, by reading the output signal whose output value exceeds the above-mentioned threshold value, it is possible to read only the output signal that is normally output, excluding the one determined as noise.

In this embodiment, in particular, a plurality of read thresholds are set.
(Two of the first threshold value Sa and the second threshold value Sb) are provided, and when the output signals from the wheel speed sensors 26 to 29 are lower in frequency than the predetermined frequency, the reading threshold value is set to the second threshold value.
Since the threshold value Sb is switched to, the output signal in such a frequency range can be read without any trouble. Further, for example, by setting another reading threshold between the thresholds Sa and Sb, the output signals from the wheel speed sensors 26 to 29 are noises under various conditions corresponding to these thresholds. Whether or not it can be determined.

Next, the discrimination of noise due to the change in the external magnetic field and the operation control of the ABS control device when this noise occurs will be described with reference to the flowcharts of FIGS. 10 and 11. When the system starts, it is first determined in step S31 whether or not the noise flag Fn is set to 1. The noise flag Fn is set to 1 while it is determined that the output signals from the wheel speed sensors 26 to 29 are noise due to changes in the external magnetic field, and when the output signals are not noise and the noise determination is canceled. It is a flag that is set or cleared to 0 when it is performed. If the determination result in the step S31 is NO, a predetermined frequency is determined in the step S32.
It is determined whether or not the output of the pulse signal of (the frequency within the range of 50 to 60 Hz in the present embodiment) is output. If the determination result is YES, the output of the wheel speed sensors 26 to 29 is determined by the first threshold value Sa. The signal is read (step S3
3). That is, the output signal whose output value does not exceed the first threshold value Sa is not read, and only the output signal whose output value exceeds the first threshold value Sa is read as the normally output output signal.

Thereafter, in step S34, it is confirmed whether or not the output signal has a frequency equal to or higher than the predetermined frequency.
In the case of ES, in step S35, the output value is the first
It is determined whether or not the threshold value Sa has been exceeded. And
If the decision result in the step S35 is YES,
In step S36, the noise flag is set to 1.
That is, the output signals from the wheel speed sensors 26 to 29 are determined to be noise due to changes in the external magnetic field. That is, the output signal whose output value does not exceed the first threshold value Sa is determined to be noise, and the first threshold value S
Only those that exceed a are read as output signals that are output normally.

As described above, according to the present embodiment, by utilizing the relationship between the frequency and the output value of the output signals from the wheel speed sensors 26 to 29, the output signal is a noise due to the change of the external magnetic field. It is possible to easily determine whether or not there is. Further, by using the first threshold value Sa, only those exceeding the threshold value Sa can be read as the normally output output signal. In particular, the first
Since the predetermined frequency corresponding to the threshold value Sa is set to a frequency within the range of 50 to 60 Hz, normally, when a high-current AC 60 Hz vehicle of the Shinkansen used for the drive system passes near the vehicle, Noise due to the accompanying change in the external magnetic field can be reliably identified. It should be noted that, as described above, the drive system of the Shinkansen is usually an alternating current 60H.
However, in the present embodiment, the predetermined frequency is set to a frequency within the range of 50 to 60 Hz in consideration of a frequency error. When it is expected that this frequency error will be above and below the usual 60 Hz, the frequency range may be set above and below including 60 Hz (for example, set to 60 Hz ± 5 Hz).

Further, the judgment result of the step S32 is N
In the case of O, in step S37, it is determined whether or not the wheel speed sensors 26 to 29 for all four wheels are in a non-pulse state (that is, a state in which the wheel speed is 0 km / hr), and the determination result is YES. In this case, in step S38, it is determined whether or not the pulse signals are output from the wheel speed sensors 26 to 29. If the decision result in the step S38 is YES, then in a step S39, for each of the wheel speed sensors 26 to 29 which have output the pulse signal, the pulse cycle from the start of the output to the predetermined number of times (the present embodiment). In the example, specifically, whether or not the period of the first pulse rising and falling from the non-pulse state corresponds to a frequency within a predetermined range (specifically, 50 to 60 Hz in the present embodiment). To be judged.

Then, if the decision result in the step S39 is YES, a noise flag is set to 1 in a step S36. That is, the wheel speed sensor 26-
The output signal from 29 is determined to be noise due to a change in the external magnetic field. More preferably, in the case where the determination result in step S39 is YES, a pulse signal in which the cycle of rising and falling of the first pulse from the non-pulse state as described above is equivalent to 50 to 60 Hz. However, four wheel speed sensors 26-29
By checking whether or not at least two of the wheel speed sensors are outputting, and performing noise determination,
More reliable noise determination can be performed.

As described above, according to this embodiment, more preferably, when the wheel speed sensors 26 to 29 output the pulse signals from the non-pulse state, the pulse cycle from the start of the output to the predetermined number of times It is possible to determine whether or not the output signal is noise due to a change in the external magnetic field. That is, in a normal state without noise, the wheel speed sensors 26 to 29 are pulseless (that is, the wheel speed is 0 k
When outputting a pulse signal from the (m / hr state) (that is,
In the case of detecting the speed at the time of starting the wheel), it is usual that the number of pulses gradually increases to some extent at first, and the number of pulses (that is, from the start of pulse signal output to about a few times) The wheel speed does not suddenly rise to a high value, and the pulse period during that time becomes quite long. In other words, the frequency corresponding to that is quite low. Therefore, when the wheel speed sensors 26 to 29 output the pulse signal from the non-pulse state, whether or not the cycle of the pulse signal from the start of the output to the predetermined number of times has a frequency of a height that does not normally occur at the time of starting the wheel. By determining, it is possible to determine whether or not the output signal is noise due to a change in the external magnetic field. The above-mentioned noise determination can be performed by providing a noise determination unit mainly composed of a microcomputer in the wheel speed detection device and by this noise determination unit. A noise determination unit may be provided in the control unit (ECU 24) to perform noise determination.

In particular, in the present embodiment, the pulse cycle from the start of output to the predetermined number of times is the first pulse rise from the non-pulse state where the pulse cycle is the longest in a normal state without noise. Since the cycle is the falling period, more reliable noise determination can be performed. still,
The predetermined number of times may be set to a few times after the start of output, for example, a few times.

On the other hand, the above steps S37 to S3.
When the determination result in 9 is NO, the wheel speed sensor 26-
The pulse signal from 29 is read at the second threshold value Sb which is set lower than the first threshold value Sa by a predetermined amount (step S40). Since the read output signal is not noise due to a change in the external magnetic field, the control unit (ECU 24) of the brake control system performs normal control in step S41. Further, when the result of the determination in step S34 or step S35 is NO, the normal control is performed (step S41).

In the above subroutine, when the output signals from the wheel speed sensors 26 to 29 are determined to be noise due to changes in the external magnetic field and the noise flag Fn is set to 1 (that is, step S36 is executed). (In case)
When the control cycle is repeated, step S3
The determination result in 1 is YES, and step S42 is executed. That is, during the noise determination period (that is, during the period when the noise flag Fn is set to 1), the ECU 24 limits the increase of the estimated value when estimating the pseudo vehicle body speed. In the present embodiment, specifically, when it is determined that the output signals from the wheel speed sensors 26 to 29 are due to noise, the estimated value of the pseudo vehicle body speed is prevented from further increasing from that time point. In other words, it is set to level off.

As described above, in this embodiment, when estimating the pseudo vehicle body speed of the vehicle based on the wheel speed detected by the wheel speed detecting device, the wheel speed sensor 26 is used.
When it is determined that the output signals from the output signals ˜29 are noises due to the change of the external magnetic field, the increase in the estimated value of the pseudo vehicle body speed is limited during the noise determination period. During the judgment period, it is possible to prevent the pseudo vehicle body speed, which is generally given as the highest value among the four wheel speeds, from becoming higher than the actual value due to the influence of noise, and the driver is not expecting a driving state. And AB
It is possible to prevent the S control from being executed. That is, it is possible to avoid the influence of noise due to the change of the external magnetic field without causing a large cost increase such as in the case of changing the number of teeth of the tooth profile rotor of the wheel speed detecting device.

During the noise determination period, instead of limiting the increase in the estimated value of the pseudo vehicle body speed as described above, it is possible to more reliably prevent the ABS control from being executed in an unexpected state by the driver. , The above pseudo vehicle speed is 0
The estimation may be made on the km / hr side. Further, during the noise determination period, in order to make it difficult to enter the ABS control, the minimum value of the wheel speed for performing the ABS control may be increased by a predetermined amount. In particular,
The minimum value of the wheel speed for performing the ABS control may be increased from the usual 7.5 km / hr to 10 km / hr or more.
Alternatively, the minimum value of the pseudo vehicle body speed for performing the ABS control is set by a predetermined amount (for example, from the normal 5 km / hr to 1
It may be increased (to 0 km / hr or more). Further, during the noise determination period, the control threshold for starting the ABS control may be changed to the side where it is difficult to enter the control in order to make it difficult to enter the ABS control.
Specifically, the control threshold value of the wheel deceleration for entering the ABS control may be changed from the normal -3G to -5G. Furthermore, during the noise determination period,
In order to reliably prevent the execution of ABS control, the ABS
The control may be prohibited from starting.

After the execution of step S42, whether or not the wheel speed sensors 26 to 29 have detected a wheel speed equal to or higher than a predetermined value in step S43, that is, whether the wheel speed sensors 26 to 29 have predetermined wheel speeds. It is determined whether or not the pulse signals corresponding to the above speeds have been output for a certain period of time or longer. If the determination result is NO, further, in step S44, the wheel speed sensors 26 to
It is determined whether or not 29 continues to be in a pulseless state for a certain time or longer. If the result of this determination is NO, it is further determined in step S45 whether the output values of the output signals from the wheel speed sensors 26-29 have exceeded the first threshold value Sa, and the result of this determination is NO. In this case, the process returns to step S31 and the subsequent steps are repeatedly executed. On the other hand, if the determination result in steps S43 to S45 is YES, the noise determination is canceled and the noise flag Fn is reset to 0 in step S46.

As described above, according to the present embodiment, the pulse from the wheel speed sensor after it is determined that the output signals from the wheel speed sensors 26 to 29 are noises due to the change of the external magnetic field. The noise determination can be canceled according to the output state of the signal. That is, when the rotation speed of the wheel is higher than a certain level, the original signal level output from the wheel speed sensor is high (the output is large), so even if noise is superimposed, the detected value of the wheel speed is substantially reduced. There is no problem even if the noise determination is canceled when the pulse signal corresponding to such a high wheel speed is output for a certain time or more without any influence. Therefore, by setting the predetermined wheel speed to an appropriate value of the height at which the corresponding pulse signal is not substantially affected by noise due to changes in the external magnetic field, it is possible to release the accurate noise determination. It can be done.

Further, when the wheel speed sensor continues to be in the non-pulse state for a certain time or longer, it is considered that there is no noise. In such a case, the noise determination may be canceled. And, in particular, all four wheel speed sensors 26-2
Since the noise determination is canceled when 9 continues to be in the non-pulse state for a certain period of time, more accurate noise cancellation can be performed. Further, when the output value exceeds the first threshold value Sa, the output signal is not noise, so the noise determination is canceled.

Although the above-mentioned embodiment is concerned with the wheel speed detecting device having the electromagnetic pickup type wheel speed sensors 26 to 29 and the ABS control device having the detecting device, the present invention is as described above. Not limited to the case, other slip control device provided with a wheel speed detection device of the above type, for example, the drive wheels and the driven wheels based on the wheel speed detected by the wheel speed detection device as described above. The speed difference is calculated, and when the calculated value exceeds a predetermined value, at least one of control for applying a braking force to the drive wheels and control for reducing the engine output is performed, so-called traction. It can be effectively applied to a control device.

That is, depending on the direction of the wheel speed sensor attached to each wheel and the direction of the magnetic field generated by the passage of the Shinkansen, noise may occur only on the front wheel side or only on the rear wheel side due to changes in the external magnetic field. However, in a vehicle equipped with a traction control device, for example, if the vehicle is of a rear-wheel drive type, if noise occurs only on the rear wheel side, the speed of the drive wheel and the driven wheel is affected by this noise. The difference appears to be larger than it actually is, and it is possible that the traction control is started when the speed difference exceeds the preset threshold value.The driver performs the traction control in an unexpected driving state. There was a problem that it made me feel uncomfortable.

In the case of this traction control device, when it is determined that the output signal from the wheel speed sensor is noise due to a change in the external magnetic field, at least the braking force is applied to the driving wheels during the noise determination period. By prohibiting the control to be applied, it is possible to prevent the driving wheels from being braked by the traction control in an unexpected driving state during the noise determination period. That is, it is possible to reliably avoid the influence of noise due to the change in the external magnetic field and prevent the driver from feeling uncomfortable. The noise determination and its cancellation in the case of this traction control device can be performed in the same manner as in the case of the ABS control device.

Further, in the case of the traction control device, if the frequency of the output signal from the wheel speed sensor of the drive wheel does not change even after performing the traction control, the wheel speed sensor of the drive wheel outputs The output signal can be determined to be noise due to changes in the external magnetic field. Then, by prohibiting the execution of the traction control during the noise determination period, it is possible to prevent the driving wheels from being braked by the traction control in an unexpected driving state during the noise determination period. .

[Brief description of drawings]

FIG. 1 is an explanatory plan view schematically showing an overall configuration of a vehicle braking system of an automobile according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a braking pressure control process in the vehicle brake control system.

FIG. 3 is a time chart showing a state before and after a shift to ABS control in the brake control system.

FIG. 4 is a time chart showing states before and after the end of ABS control on a low μ road.

FIG. 5 is a time chart showing states before and after ABS control on a high μ road.

FIG. 6 is an explanatory diagram of a wheel speed sensor mounted on the automobile.

FIG. 7 is an explanatory diagram showing an output level and a noise level of a wheel speed sensor in a high speed range.

FIG. 8 is an explanatory diagram showing a signal reading level and a noise level of the ABS control device at a low speed range or when the vehicle is stopped.

FIG. 9 is an explanatory diagram showing a reading threshold when reading an output signal from a wheel speed sensor.

FIG. 10 is a part of a flowchart showing noise determination processing and determination cancellation processing in the brake control system.

FIG. 11 is a part of a flowchart showing noise determination processing and determination cancellation processing in the brake control system.

[Explanation of symbols]

 1, 2, 3, 4 ... Wheels 24 ... Control unit (ECU) 26, 27, 28, 29 ... Wheel speed sensor Sa ... First threshold value Sb ... Second threshold value Vr ... Pseudo vehicle speed W1, W2, W3, W4 ... Wheel speed

Claims (25)

[Claims] 1. An electromagnetic pickup type wheel speed sensor for converting a magnetic flux change into a voltage signal and outputting a pulse signal having a frequency corresponding to the frequency of the magnetic flux change, based on an output signal from the wheel speed sensor. A wheel speed detecting device for detecting a wheel speed, wherein a threshold value corresponding to a sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency is set in advance,
When the output value from the wheel speed sensor is equal to or higher than the predetermined frequency but the output value does not exceed the threshold value, the output signal from the wheel speed sensor is noise due to a change in the external magnetic field. A wheel speed detecting device characterized in that 2. An electromagnetic pickup type wheel speed sensor for converting a magnetic flux change into a voltage signal and outputting a pulse signal having a frequency corresponding to the frequency of the magnetic flux change, based on an output signal from the wheel speed sensor. A wheel speed detecting device for detecting a wheel speed, wherein a reading threshold when reading an output signal from the wheel speed sensor is at least a sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency. A plurality of corresponding first threshold values and second threshold values smaller by a predetermined amount than these are set, and when the frequency of the output signal from the wheel speed sensor is equal to or higher than the predetermined frequency, the output value is The output signal that does not exceed the first threshold value is determined to be noise due to a change in the external magnetic field, and only the output signal whose output value exceeds the first threshold value is read. That the wheel speed detection device. 3. After the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, the wheel speed sensor outputs a pulse signal having a frequency equal to or higher than the predetermined frequency for a predetermined time or more. The noise determination is canceled when the output value exceeds a threshold value corresponding to the sensor output value when the pulse signal of the predetermined frequency is output. 2. The wheel speed detection device according to 2. 4. After the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, a pulse signal corresponding to a speed equal to or higher than a predetermined wheel speed is output from the wheel speed sensor for a certain period of time or more. When output,
2. The noise determination is canceled.
Alternatively, the wheel speed detecting device according to claim 2. 5. The wheel speed sensor is attached to each of four wheels of a vehicle, and after it is determined that output signals from the wheel speed sensors are noises due to a change in an external magnetic field, all the four wheels are The wheel speed detecting device according to claim 1 or 2, wherein the noise determination is canceled when the wheel speed sensor of 1 continues to be in a pulse-free state for a certain period of time or more. 6. The method according to claim 1, wherein the predetermined frequency is within a range of 50 to 60 Hz.
The wheel speed detection device according to any one of 1. 7. A wheel speed for detecting a wheel speed based on an output signal from an electromagnetic pickup type wheel speed sensor which converts a change in magnetic flux into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the change in magnetic flux. A detection device, hydraulic pressure adjusting means for adjusting the braking pressure of each wheel, and operating the hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting device cyclically increases or decreases the braking pressure of each wheel. A slip control device for a wheel, comprising: an anti-skid control means for controlling the wheel speed, wherein a threshold value corresponding to a sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency is preset. When the frequency of the output signal from the sensor is equal to or higher than the predetermined frequency but the output value does not exceed the threshold value, the wheel speed sensor outputs Force signal is a wheel slip control system, characterized in that it is determined that a noise due to changes in the external magnetic field. 8. A wheel speed for detecting a wheel speed based on an output signal from a wheel speed sensor of an electromagnetic pickup type which converts a change in magnetic flux into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the change in magnetic flux. A detecting device, a hydraulic pressure adjusting means for adjusting the braking pressure of each wheel, and a braking pressure of each wheel is periodically increased or decreased by operating the hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting device. A slip control device for a wheel, comprising: an anti-skid control means, wherein a reading threshold when reading an output signal from the wheel speed sensor is at least when the wheel speed sensor outputs a pulse signal of a predetermined frequency. Are set to include a first threshold value corresponding to the sensor output value of No. 2 and a second threshold value that is smaller than this by a predetermined amount, and the output from the wheel speed sensor is set. When the frequency of the signal is above the predetermined frequency, the output signal whose output value does not exceed the first threshold value is determined to be noise due to changes in the external magnetic field, the output value of the first
A slip control device for a wheel, wherein only an output signal exceeding a threshold value is read. 9. A pulse signal having a frequency equal to or higher than the predetermined frequency is output from the wheel speed sensor for a certain period of time or more after it is determined that the output signal from the wheel speed sensor is noise due to a change in an external magnetic field. The noise determination is canceled when the output value exceeds a threshold value corresponding to the sensor output value when the pulse signal of the predetermined frequency is output. 8. The wheel slip control device according to item 8. 10. After the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, a pulse signal corresponding to a speed equal to or higher than a predetermined wheel speed is output from the wheel speed sensor for a predetermined time or more. 9. The wheel slip control device according to claim 7, wherein the noise determination is canceled when the wheel slip is output. 11. The wheel speed sensor is attached to each of four wheels of a vehicle, and after the output signals from the wheel speed sensors are determined to be noise due to a change in an external magnetic field, all the four wheels are 9. The wheel slip control device according to claim 7, wherein the noise determination is canceled when the wheel speed sensor of 1 continues to be in a pulse-free state for a certain period of time or more. 12. The wheel slip control device according to claim 7, wherein the predetermined frequency is a frequency within a range of 50 to 60 Hz. 13. The wheel slip control device, when estimating a pseudo vehicle body speed of the vehicle based on the wheel speed detected by the wheel speed detecting device, outputs an output signal from the wheel speed sensor to an external magnetic field. When it is determined that the noise is due to a change in the noise, the increase in the estimated value of the pseudo vehicle body speed is limited during the noise determination period. A slip control device for a wheel according to item 1. 14. The wheel slip control device, when the pseudo vehicle body speed of the vehicle is estimated based on the wheel speed detected by the wheel speed detection device, outputs an output signal from the wheel speed sensor to an external magnetic field. When it is determined that the noise is due to a change in the noise, the pseudo vehicle body speed is estimated to be 0 km / hr during the noise determination period. A slip control device for a wheel according to item 1. 15. If the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, the wheel slip control device may perform the anti-skid control during the noise determination period. The wheel slip control device according to any one of claims 7 to 12, wherein the minimum value of the wheel speed for performing the above is increased by a predetermined amount. 16. The anti-skid control device for a slip control device for a wheel, when the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, during the noise determination period. The wheel slip control device according to any one of claims 7 to 12, wherein a control threshold for starting the control is changed to a side in which control is difficult to enter. 17. If the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, the wheel slip control device may perform the anti-skid control during the noise determination period. 13. The wheel slip control device according to any one of claims 7 to 12, wherein the start of the slip control is prohibited. 18. A wheel speed for detecting a wheel speed based on an output signal from a wheel speed sensor of an electromagnetic pickup type which converts a change in magnetic flux into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the change in magnetic flux. The speed difference between the drive wheel and the driven wheel is calculated based on the wheel speed detected by the detection device and the wheel speed detection device. When the calculated value exceeds a predetermined value, the braking force is applied to the drive wheel. A wheel slip control device comprising a traction control means for performing at least one of control for acting and control for reducing an engine output, wherein the sensor output when the wheel speed sensor outputs a pulse signal of a predetermined frequency. The threshold value corresponding to the value is set in advance, and the output value of the wheel speed sensor is set to the output value even if the output signal frequency is equal to or higher than the predetermined frequency. When not exceeding the threshold value, the output signal from the wheel speed sensor is a wheel slip control system, characterized in that it is determined that a noise due to changes in the external magnetic field. 19. A wheel speed for detecting a wheel speed based on an output signal from a wheel speed sensor of an electromagnetic pickup type which converts a change in magnetic flux into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the change in magnetic flux. The speed difference between the drive wheel and the driven wheel is calculated based on the wheel speed detected by the detection device and the wheel speed detection device. When the calculated value exceeds a predetermined value, the braking force is applied to the drive wheel. A slip control device for a wheel, comprising a traction control means for performing at least one of a control for operating and a control for reducing an engine output, wherein a reading threshold when reading an output signal from the wheel speed sensor is at least A first threshold value corresponding to a sensor output value when the wheel speed sensor outputs a pulse signal of a predetermined frequency, and a second threshold value which is a predetermined amount smaller than the first threshold value. If the frequency of the output signal from the wheel speed sensor is equal to or higher than the predetermined frequency, the output signal whose output value does not exceed the first threshold value is noise due to a change in the external magnetic field. It is determined that the output value is the first
A slip control device for a wheel, wherein only an output signal exceeding a threshold value is read. 20. After the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, the wheel speed sensor outputs a pulse signal having a frequency equal to or higher than the predetermined frequency for a predetermined time or more. The noise determination is canceled when the output value exceeds a threshold value corresponding to the sensor output value when the pulse signal of the predetermined frequency is output. 19. The wheel slip control device according to item 19. 21. After the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, a pulse signal corresponding to a speed equal to or higher than a predetermined wheel speed is output from the wheel speed sensor for a predetermined time or more. 20. The wheel slip control device according to claim 18 or 19, wherein the noise determination is canceled when the slip is output. 22. The wheel speed sensors are attached to each of four wheels of a vehicle, and after it is determined that output signals from the wheel speed sensors are noises due to a change in an external magnetic field, all the four wheels are 20. The noise determination is canceled when the wheel speed sensor of 1 continues a pulse-free state for a certain period of time or more.
A slip control device for a wheel according to item 1. 23. The wheel slip control device according to claim 18, wherein the predetermined frequency is a frequency within a range of 50 to 60 Hz. 24. When the output signal from the wheel speed sensor is determined to be noise due to a change in an external magnetic field, the wheel slip control device at least the drive wheel during the noise determination period. The wheel slip control device according to any one of claims 18 to 23, characterized in that a control for applying a braking force to the wheel is prohibited. 25. A wheel speed for detecting a wheel speed based on an output signal from an electromagnetic pickup type wheel speed sensor which converts a change in magnetic flux into a voltage signal and outputs a pulse signal having a frequency corresponding to the frequency of the change in magnetic flux. The speed difference between the drive wheel and the driven wheel is calculated based on the wheel speed detected by the detection device and the wheel speed detection device. When the calculated value exceeds a predetermined value, the braking force is applied to the drive wheel. A slip control device for a wheel, comprising a traction control means for performing at least one of a control for operating and a control for reducing an engine output, the output from a wheel speed sensor for the drive wheel even if the traction control is performed. If the frequency of the signal does not change, the output signal from the wheel speed sensor is determined to be noise due to a change in the external magnetic field, and the noise determination period The wheel slip control system, characterized in that prohibits execution of the traction control.