JPH0614060B2 - Vehicle wheel slip detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wheel slip detection device for detecting a state where a drive wheel of an automobile is idling, that is, a slip state.

(Prior Art) Conventionally, as a wheel slip detection device for an automobile of this type, for example, as disclosed in Japanese Utility Model Publication No. 51-44046, rotation speeds of driving wheels and idle wheels are detected by a rotation detector, It is known that the slip state of the drive wheels is detected based on the difference between the two rotational speeds.

However, in the above-mentioned conventional one, it is necessary to accurately detect the absolute value of each rotation speed by the rotation detector because the slip state is detected by the difference in rotation speed between the drive wheel and the idle wheel. Therefore, it is necessary to use a rotation detector with high detection accuracy, which is a costly problem. Further, when traveling on a rough road, the rotational speeds of the drive wheel and the idle wheel both change drastically, making it difficult to obtain the rotational speed difference between the two wheels.

(Object of the Invention) In view of such a point, an object of the present invention is, in particular, a wheel (driving wheel).
Is slipping only when changing the vehicle speed, and at the time of slipping, the rotation speed of the idle wheel does not change even if the rotation speed of the drive wheels changes, and the correlation function between the two collapses. The purpose of the present invention is to provide a wheel slip detection device for automobiles that detects this collapsed state so that the slip state can be easily and accurately detected, is inexpensive, and has high detection accuracy and is highly practical. is there.

(Structure of the Invention) In order to achieve the above object, the present invention provides: a first rotation speed detecting means for detecting a rotation speed of a drive wheel; a second rotation speed detecting means for detecting a rotation speed of an idle wheel; 1st and 2nd
From the comparison of the frequencies of the first and second frequency conversion means for frequency-converting the signals of the rotation speed detection means and the frequencies of the first and second rotation speed detection means frequency-converted by both frequency conversion means, the drive wheel and the idle wheel are compared. Comparing means for calculating a correlation function representing a deviation of the changing frequency of the rotational speed of the wheel, and detecting that the correlation function calculated by the comparing means is different from the reference correlation function and issuing a signal indicating the slip state of the wheel. It is constituted by a judging means. As a result, when the drive wheel slips when changing the vehicle speed, the correlation function that represents the deviation of the change frequency of the rotational speed of the drive wheel and the idle wheel collapses, and the wheel is detected based on the detection of the collapsed state of this correlation function. The slip state is detected.

(Effect of the Invention) Therefore, according to the vehicle wheel slip detection device of the present invention, the slip state of the wheel is detected based on the detection of the correlation function that represents the deviation of the change frequency of the rotational speeds of the drive wheel and the idle wheel. Therefore, it is not necessary to accurately detect even the absolute value of the rotation speed of the drive wheel or the idle wheel by using the high-precision rotation speed detection means as in the prior art. It is enough to use. Also,
It is possible to reliably detect the slip of the drive wheel even when the drive wheel and the idle wheel both change drastically when driving on a rough road.
Therefore, cost reduction and improvement in detection accuracy can be effectively achieved.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows a schematic configuration of an FR (front engine / rear drive) type vehicle equipped with a wheel slip detection device according to an embodiment of the present invention, where 1 is a vehicle body and 2 is a front portion of the vehicle body 1. The engine 3 is a transmission that is connected to the rear portion of the engine 2, and the transmission 3 is connected to the left and right rear wheels (driving wheels) 7 and 7 via the propulsion shaft 4, the differential 5 and the rear axle 6. It is connected so that power can be transmitted.

Further, 8 and 8 are first rotation speed detecting means for detecting the rotation speeds of the left and right rear wheels 7 and 7, and 9 and 9 are left and right front wheels (idling wheels).
Second rotational speed detecting means for detecting the rotational speeds of 10, 10 and each of these four rotational speed detecting means 8, 9 is connected to an electronic determination circuit 11 for making a slip determination so that signals can be exchanged. There is.

As shown in FIG. 2, the electronic determination circuit 11 includes a frequency-voltage converter 12 as first frequency conversion means for frequency-converting the signals of the first rotation speed detection means 8 and 8, and the rotation speed detection means. A first filter 13 for removing noise from the signals of the means 8 and 8, and a frequency-voltage converter 15 as second frequency conversion means for frequency-converting the signals of the second rotation speed detection means 9 and 9. And a second filter 16 for removing noise of the signals of the rotation speed detecting means 9, 9.

Further, the electronic determination circuit 11 receives the signal of the first rotation speed detection means 8 that has been frequency-converted by the first frequency-voltage converter 12, and calculates the power spectrum of the rotation speed of the drive wheels 7 in the first calculation. The circuit 14 and the second rotation speed detecting means 9 whose frequency is converted by the second frequency-voltage converter 15 described above.
Signal from the second calculation circuit 17 for calculating the power spectrum of the rotational speed of the idler wheel 10, and the first and second frequency-voltage converters 12 and 15 for frequency conversion respectively. A third calculation circuit 18 which receives signals from the rotation speed detection means 8 and 9 and calculates a cross spectrum of the rotation speeds of the drive wheel 7 and the idle wheel 10, and the first, second and third calculation circuits 14, Receive the signals of 17 and 18,
A fourth calculation circuit 19 for calculating a correlation function (hereinafter, referred to as coherency) that expresses a deviation of the change frequency of the rotational speeds of the drive wheel 7 and the idle wheel 10 is provided, and these four calculation circuits 14, 17 to 19 are provided. Thus, the comparison means 20 is configured to calculate the coherency of the rotation speeds of the drive wheel 7 and the idle wheel 10 by comparing the frequencies of the signals of the first and second rotation speed detection means 8 and 9.

Further, the electronic judging circuit 11 is connected to the fourth calculating circuit 19 of the comparing means 20 so as to be able to send and receive signals.
The determination means 21 includes a reference coherency (a drive wheel 7 and an idle wheel when the drive wheel 7 rolls normally without slipping), which stores the coherency calculated by the comparison means 20 in advance. 10), the "H" signal indicating the slip state of the wheel is issued when it is detected that the coherency is different from the reference coherency. As described above, the wheel slip detecting device A of the present invention is configured to detect the slip state of the wheel based on the detection of the coherency of the rotational speeds of the drive wheel 7 and the idle wheel 10.

When the slip state of the wheel is detected by the wheel slip detecting device A (the judging means 2 of the electronic judging circuit 11).
When the "H" signal is output from 1), as a countermeasure against the slip, an alarm buzzer sounds with a detection signal "H" signal to alert the driver or the suspension is supported to suppress the slip. The rigidity and the output of the engine are changed.

Next, the operation of the above-described embodiment will be described. When the vehicle is suddenly accelerated or rapidly decelerated on a road (low μ road) where the friction resistance coefficient of the road surface is small due to wetting, freezing, etc., the drive wheels 7 are By slipping on the road surface, the idle wheel 10
The rotation speed of 1 does not follow the change of the rotation speed of the drive wheel 7, and the coherency of the rotation speed of both wheels 7 and 10 collapses.

At this time, in the electronic determination circuit 11 of the wheel slip detection device A of the present invention, the drive wheels 7 calculated by the comparison means 20 are calculated.
The determination means 21 detects that the coherency of the rotational speeds of the idler wheel 10 and the idle wheel 10 is different from the reference coherency, and the determination means 21 outputs an "H" signal indicating the slip state of the wheels.

Here, in the comparison means 20, the drive wheel 7 and the idle wheel 1
Waveforms in the process of calculating the coherency of the rotational speed with 0 are shown in FIGS. 3 (a) to 3 (d). FIG. 3 (a) shows the power spectrum of the drive wheel 7 calculated by the first calculation circuit 14, and FIG. 3 (b) shows the power spectrum of the idle wheel 10 calculated by the second calculation circuit 17. FIG. 3C shows the cross spectra of the rotational speeds of the driving wheel 7 and the idle wheel 10 calculated by the third calculating circuit 18, and FIG. 3D shows the fourth calculating circuit 19 based on these spectra.
It shows the coherency of the rotational speeds of the drive wheel 7 and the idle wheel 10 calculated in. The power spectrum represents the frequency of change of the wheel rotation speed in a predetermined time width. Therefore, when the fluctuation cycle of the wheel rotation speed is discontinuous, the power spectrum can be obtained over a wide frequency range. The cross spectrum indicates the degree of association of the drive wheel 7 with the idle wheel 10. Coherency
It shows the deviation of the changing frequency of the rotational speeds of the drive wheel 7 and the idle wheel 10. When the coherency value is "1", it means that there is no deviation of the changing frequency.

As can be seen from FIG. 3, the power spectrum of the drive wheel 7 and the power spectrum of the idle wheel 10 do not match at all due to the slip of the drive wheel 7, and due to this mismatch, the rotational speeds of both wheels 7, 10 are The coherency has a complicated waveform including a sharp drop and a rising at a certain frequency or higher.
Then, the complex waveform of this coherency is the determination means 2
This is different from the simple waveform that does not include the sharp drop and rise as the reference coherency stored in 1.

On the other hand, on ordinary roads (high μ
When traveling normally on a road, the drive wheels 7 roll on the road without slipping, and the rotation speed of the drive wheels 7 and the idle wheel 10
The rotation speed is maintained in a one-to-one proportional relationship.

At this time, in the electronic determination circuit 11 of the wheel slip detection device A, the coherency of the rotational speeds of the driving wheel 7 and the idle wheel 10 calculated by the comparison means 20 is determined by the determination means 21 to match the reference coherency. ,
No "H" signal indicating the slip condition of the wheel is issued from the judging means 21. Although the waveforms of the processing steps for calculating the coherency of the rotational speeds of the drive wheel 7 and the idler wheel 10 by the comparison means 20 are not particularly shown, the power spectrum of the drive wheel 7 and the idler wheel 10 are not shown.
Is almost the same as the power spectrum of the above, and the coherency of the rotation speed between the wheels 7 and 10 is a simple waveform that does not include a sudden drop and a rise.

As described above, the slip detection in the wheel slip detection device A of the present invention is based on whether or not the coherency of the rotational speeds of the drive wheel 7 and the idle wheel 10 is different from the reference coherency. As the rotation speed detecting means 8 and 9 for detecting the rotation speed of the idle wheel 10,
It is not necessary to use a high-precision one that can accurately detect the absolute value of the rotation speed as in the case where the difference between the rotation speeds of the conventional drive wheel and the idler wheel is based on whether the difference is greater than or equal to the set value. It is possible to use the one having the ordinary precision sufficient to obtain the coherency of, and thus the cost can be reduced.

Moreover, even when the rotational speeds of the drive wheel 7 and the idle wheel 10 both change drastically, such as when driving on a rough road, the power spectrum or coherency of the drive wheel 7 and the idle wheel 10 can be easily obtained. Since the slip can be reliably detected by comparison with the coherency, the detection accuracy can be improved.

The present invention is not limited to the above-mentioned embodiments, but includes various other modified examples. For example, in the above embodiment, the electronic determination circuit 11 including the comparison means 20 and the determination means 21 is used to perform the slip determination, but instead of the electronic determination circuit 11, a microcomputer is used to perform the slip determination. May be configured to perform.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a schematic configuration diagram, FIG. 2 is an electronic circuit diagram, and FIGS. 3 (a) to 3 (d) are low μ.
It is a wave form diagram of the processing process in the comparison means at the time of sudden acceleration or sudden deceleration traveling on the road. A: Wheel slip detector, 7: Rear wheel (driving wheel),
8 ... 1st rotation speed detection means, 9 ... 2nd rotation speed detection means, 10 ... front wheel (idle wheel), 11 ... electronic determination circuit, 20 ... comparison means, 21 ... determination means.

Claims (1)

[Claims] 1. A first rotation speed detecting means for detecting a rotation speed of a drive wheel, a second rotation speed detecting means for detecting a rotation speed of an idle wheel, and signals of the first and second rotation speed detecting means. First and second frequency converting means for respectively frequency converting,
Comparing means for calculating a correlation function representing the deviation of the changing frequency of the rotational speeds of the drive wheel and the idle wheel from the comparison of the frequencies of the signals of the first and second rotational speed detecting means which are frequency-converted by the both frequency converting means. And a determination means for detecting that the correlation function calculated by the comparison means is different from the reference correlation function and for issuing a signal indicating the slip state of the wheels.