JPH04185569A - Method of failure judgement of wheel speed sensor in anti--skid brake controller - Google Patents

Abstract

PURPOSE:To accurately judge the failure of a wheel speed sensor even at the time of anti-skid control by setting a reference reduction wheel speed for judging failure to a small level at the time of normal driving, and by setting it to a large level at the time of anti-skid brake control. CONSTITUTION:A wheel reduction speed is calculated based on the wheel speed determined by the wheel speed signal from a wheel speed sensor, and the failure of the wheel speed sensor is judged when the wheel reduction speed is larger than a reference reduction wheel speed. In this method of failure judgement, two different values are set as reference reduction speed, and the failure of wheel speed sensor is judged by using the smaller reference reduction wheel speed of the set two values, at the time of normal driving, while the larger one of the reference reduction wheel speed is used as a reference, at the time of anti-skid brake control. Even in an anti-skid control, during which relatively large reduction wheel speed is generated, the failure of wheel speed sensor can be accurately judged.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an anti-skid brake control method for a vehicle, and more particularly to a failure determination method for a wheel speed sensor in an anti-skid brake control device that determines failure by detecting disconnection of a wheel speed sensor.

[Conventional technology]

Generally, anti-skid brake control detects that a wheel is in a skid state during braking, reduces the braking force on that wheel to eliminate the skid state, and then increases the braking force again to control vehicle operation. Brake control is performed to stabilize the vehicle and to shorten the braking distance as much as possible. Conventionally, in such anti-skid brake control, wheel speed sensors have been used to detect wheel speeds. It consists of an exciter ring for speed detection consisting of a gear, and a pulse signal generating means that electromagnetically detects the teeth of the exciter and generates a pulse signal. Based on the pulse signal from this wheel speed sensor, the electronic control unit determines whether or not the brake wheels are skidding during braking, and if the brake wheels are skidding, performs anti-skid control. It is supposed to be done. By the way, when performing anti-skid control using such a wheel speed sensor, it is necessary to ensure that the anti-skid control is performed accurately, and one of the ways to do this is to ensure that the wheel speed sensor always operates reliably to control the wheel speed. It is required to accurately detect the Therefore, in conventional anti-skid brake control, the wheel speed sensor is constantly diagnosed to ensure that the Wr line failure is detected. In this case, as a method for detecting a disconnection failure of the wheel speed sensor, a disconnection failure of the wheel speed sensor is determined based on a sudden decrease in the wheel speed signal from the wheel speed sensor.

[! ! Issues that Ming is trying to solve】

However, during anti-skid brake control, the wheel speed signal from the wheel speed sensor sharply decreases, so determining a disconnection failure of the wheel speed sensor based on the sudden decrease in the wheel speed signal like this is not enough. Even when the wheel speed suddenly decreases due to a skid, it may be erroneously determined that there is a disconnection failure in the wheel speed sensor, and anti-skid brake control may not be performed. In order to prevent this misjudgment, if the wheel deceleration, which is the standard for failure determination, is made much larger than the wheel deceleration during anti-skid brake control, the failure of the wheel speed sensor cannot be reliably detected. There is. The present invention has been made in view of the above circumstances, and an object thereof is to provide a failure determination method in an anti-skid brake control device that can reliably detect a failure of a wheel speed sensor. .

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention calculates wheel deceleration based on the wheel speed determined by the wheel speed signal from the wheel speed sensor, and calculates the calculated wheel deceleration based on the wheel speed signal from the wheel speed sensor. In a method for determining failure of a wheel speed sensor in an anti-skid brake control device in which it is determined that the wheel speed sensor has failed when the wheel speed sensor is larger than a reference wheel deceleration for determining a disconnection failure, two different sizes are used as the reference wheel deceleration. During normal driving, failure of the wheel speed sensor is determined based on the reference wheel deceleration, which is the smaller of the two set values, and during anti-skid brake control, the wheel speed sensor failure is determined based on the reference wheel deceleration, which is the smaller of the two set values. The system is characterized in that failure of the wheel speed sensor is determined based on the reference wheel deceleration, which is the larger of the two values.

[Effect]

In the method for determining failure of a wheel speed sensor in an anti-skid brake control device according to the present invention having such a configuration, the base single wheel deceleration for determining failure is set small during normal driving, and at the same time during anti-skid brake control. It is set large. Therefore, even during anti-skid control when a relatively large wheel deceleration occurs, it is possible to accurately determine the failure of the wheel speed sensor, and since the reference wheel deceleration is small during normal driving, failure can be reliably detected. can be detected.

【Example】

Hereinafter, the present invention will be explained in detail using the drawings. FIG. 1 is a diagram showing a wheel speed calculation method used in an embodiment of a wheel speed sensor failure determination method in an anti-skid brake control device according to the present invention. In determining whether or not the wheel speed sensor has a disconnection failure, this embodiment determines failure based on a sudden decrease in wheel speed, as in the prior art. for that,
First, it is necessary to find the wheel speed, and the method for finding the wheel speed will be explained below. FIG. 1 is a diagram showing a wheel speed calculation method used in an embodiment of a wheel speed sensor failure determination method in an anti-skid brake control device according to the present invention. In Figure 1, the wheel speed is determined by the number of pulses n from the wheel speed sensor taken in each cycle (n = 3 in the example shown) and the last pulse Pa of the previous cycle. It is calculated from the time t from when the last pulse Pb of the current cycle is input. That is, first, the average period of pulses from the wheel speed sensor is determined. The average period of this pulse is calculated by Tav==t/n. Next, the wheel speed is determined using the average period Tav of this pulse. That is, the wheel speed is calculated by v=c/Tav. Here, C is a speed constant, and when the tire diameter is r, it is calculated by c=2πr/(number of exciter ring teeth). For example, tire diameter r=0.509
m, number of teeth of exciter ring = 100, then c=
0.032m.As shown in Figure 1, if the pulse from the wheel speed sensor is interrupted for one cycle or more due to a wire breakage, etc., the average pulse period of the first cycle is Tav=
10ms, and the average pulse period of the second cycle is T.
We estimate that the time when the signal is interrupted is the pulse period of that cycle, such that we estimate av = 20 ms. In this case, the wheel speed for each cycle is estimated from this estimated cycle. That is, in the first cycle, the estimated wheel speed V, , is v,1=0.032m/l0m5
= 3.2+n/s=approximately 11.5 k+n/h,
In the second cycle, the estimated wheel speed Vv2 is v wt
=0.032m/20m5= 1.6m/s=approx. 6k
It is rn/h. Thereafter, the estimated wheel speed is calculated in the same manner from the third cycle onwards. Based on the estimated wheel speed calculated in this way, the magnitude of decrease in wheel deceleration from the previous cycle to the current cycle is determined. By the way, in this embodiment, as shown in FIG. 1, when no pulse input is received for 64 see after the wheel speed sensor is disconnected, it is determined that the wheel speed sensor is in a momentary disconnection failure. Further, in this embodiment, two values of different magnitudes are set for the wheel deceleration, which is a reference for determining a disconnection failure of the wheel speed sensor. During normal driving, failure of the wheel speed sensor is determined based on the deceleration of the smaller set value, and during anti-skid brake control, the wheel speed sensor is determined based on the deceleration of the larger set value. It is designed to determine if the speed sensor is malfunctioning. Hereinafter, a method for determining failure of the wheel speed sensor in this embodiment will be explained using FIG. 2. FIG. 2 is a diagram showing the logic for determining momentary interruption of the wheel speed sensor. In Figure 2, this logic starts false Step 1
, it is determined whether the vehicle speed V is greater than 15 km/h (v>15 km/h?). V〉15km
/h, no test is performed. ■〉+n to 15
/h, it is determined in step 2 whether the determination of instantaneous sensor interruption failure has been established. When the determination of instantaneous sensor interruption failure is confirmed, this determination of instantaneous sensor interruption failure is maintained and no test is performed. If the determination of instantaneous sensor disconnection failure is not confirmed, it is determined in step 3 whether or not sensor disconnection is being diagnosed. If it is determined that the sensor disconnection is being diagnosed, it is determined in step 4 whether the wheel speed is O. That is, it is determined whether or not there is a pulse input from the wheel speed sensor during the cycle. If no pulse is input, it is determined in step 5 whether 64+ns have elapsed since the pulse signal was discontinued. When it is determined that 64 m5 have elapsed since the pulse signal was discontinued, it is determined in step 6 that a sensor instantaneous failure has occurred, and the next process 7, for example, exciter abnormality detection process, is performed. If it is determined in step 3 that the sensor disconnection is not being diagnosed, step 8 determines the wheel speed v1 of the current cycle. is less than or equal to the wheel speed Vbl of the previous cycle (vl,
≦vwb? ) to judge. This time the wheel speed is V. , ≦previous wheel speed VMk, it is determined that the vehicle is accelerating, and in step 9, the sensor is determined to be normal, and the disconnection diagnosis (watching) is terminated, and the next process 7 is performed. In step 8, current wheel speed v, ≦previous wheel speed V
If it is determined that the vehicle is bl+, it is determined that the vehicle is decelerating,
In step 1o, it is determined whether the wheel speed is O. If it is determined that the wheel speed is not 0, the next process 7 is performed. When it is determined in step 10 that the wheel speed is O, it is determined in step 11 whether anti-skid control is being performed. If it is determined that anti-skid control is in progress, in step 12, the wheel speed V of the previous cycle is determined. and the current cycle's wheel speed v, it is determined whether the difference is greater than 30 km/h (V wbV y@> 30 k+n/h). Previous wheel speed v1-・current wheel speed V vs>
If it is determined that the speed is 30 km/h, in step 13, diagnosis is started as a sensor disconnection. If it is determined in step 12 that the previous wheel speed V, . In step 11, if anti-skid control is not in progress, it is determined that the vehicle is running normally, and in step 14, the difference between the wheel speed v of the previous cycle and the wheel speed Vil of the current cycle is greater than 15 km/h. Or not (V
wb V wb > 15 km/h). Previous wheel speed V, - current wheel speed V,,) 15
If it is determined that the speed is km/h, in step 13, diagnosis is started as a sensor disconnection. In step 14, previous wheel speed Vvb - current wheel speed V. a＞15km/h
(in other words, there is no pulse input during the cycle), the processes from step 8 onwards are performed as described above. Also, in step 5, after the pulse signal is interrupted,
If it is determined that 64 m5ec has not elapsed, the processing from step 8 onwards is similarly performed. In this way, a failure determination of the wheel speed sensor is performed. As described above, in this embodiment, the reference wheel deceleration for determining a disconnection failure of the wheel speed sensor has two different values, namely, 15 k+n/h/10 is and 30
k+n/h/l Oras, 15 k+n/h/10 ma is selected during normal driving, and 30 km during anti-skid brake control.
/h/ 10■S is selected.

【Effect of the invention】

As is clear from the above explanation, according to the wheel speed sensor failure determination method in the anti-skid brake control device according to the present invention, the reference wheel deceleration for determining failure is set small during normal driving, and the Since it is set to a large value during skid brake control, it is possible to accurately determine the failure of the wheel speed sensor even during anti-skid control. Furthermore, since the reference wheel deceleration is small during normal driving, failures can be reliably detected. By using the present invention in this way, the reliability of the anti-skid control device can be further improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a wheel speed calculation method used in an embodiment of a wheel speed sensor failure determination method in an anti-skid brake control device according to the present invention.

FIG. 2 is a diagram showing logic for determining momentary interruption of a wheel speed sensor.

Claims (4)

[Claims] 1. A wheel deceleration is calculated based on a wheel speed determined from a wheel speed signal from a wheel speed sensor, and the calculated wheel deceleration is a criterion for determining a disconnection failure of the wheel speed sensor. In a method for determining failure of a wheel speed sensor in an anti-skid brake control device in which it is determined that the wheel speed sensor has failed when the wheel speed sensor is larger than the wheel deceleration, two values different in size are set as the reference wheel deceleration, and In this case, failure of the wheel speed sensor is determined based on the reference wheel deceleration which is the smaller of the two values set above, and during anti-skid brake control, the reference wheel deceleration is determined based on the reference wheel deceleration which is the smaller of the two values set above. A method for determining failure of a wheel speed sensor in an anti-skid brake control device, comprising determining failure of a wheel speed sensor based on wheel deceleration. 2. A failure of the wheel speed sensor is determined when the wheel speed signal is not input even after a predetermined period of time has elapsed since the wheel speed signal from the wheel speed sensor was interrupted. 1. A method for determining failure of a wheel speed sensor in the anti-skid brake control device according to item 1. 3. The method for determining failure of a wheel speed sensor in an anti-skid brake control system according to claim 1, wherein the wheel speed signal from the wheel speed sensor is a pulse signal. 4. The wheel speed is calculated based on the number of pulses of the pulse signal input in each cycle of a certain period of time, and the number of pulses in the current cycle from the time when the last pulse in the previous cycle was input. 4. The method for determining failure of a wheel speed sensor in an anti-skid brake control device according to claim 3, wherein the calculation is performed based on the time until the brake is applied.