JPS63172967A - Wheel speed detector - Google Patents

Abstract

PURPOSE:To correct a pulse period at the time of abnormality and to accurately detect a wheel speed by comparing the period of a pulse signal generated in response to a tooth of a pulse gear rotating together with a wheel with a precedent pulse period. CONSTITUTION:The pulse gear 2 rotates during the traveling of a vehicle together with the wheel 1 and a rotation sensor 3 generates a pulse signal by the passage of this gear 2. A wheel speed detector 4 finds the speed of the wheel from the period of this pulse signal. At thim time, a pulse period abnormality deciding means 6 compares the period of the pulse signal with the preceding pulse period to decide whether or not abnormality occurs and if the abnormality occurs, a pulse period correcting means 7 corrects the abnormal pulse period according to the relation to the precedent period. Thus, deviation in pulse signal period due to the corrosion, etc., of pulse gear teeth is corrected, so the wheel speed is accurately detected to hold the operation accuracy of an anti-skid controller 5 high.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wheel speed detection device for an anti-skid control device that prevents wheels from locking during braking.

(Prior art) An anti-skid control device reduces the brake fluid pressure when the wheels are locked, where the wheel circumference is fast and the wheel speed has a predetermined slip relationship with the vehicle speed, and increases the brake fluid pressure when the wheels are unlocked. By repeating the skid cycle, wheel lock is prevented to obtain maximum braking efficiency.

Therefore, a wheel speed detection device that detects the wheel speed is essential for an anti-skid control device, but this wheel speed detection device is generally based on the period of a pulse signal from a rotation sensor that detects the passage of teeth of a pulse gear that rotates with the wheel. It was common to find the wheel speed (as described in Japanese Patent Publication No. 56-24225).

(Problems to be Solved by the Invention) However, in such conventional wheel speed detection devices, when the machining accuracy of the pulse gear is poor and there is an error in the tooth pitch, or the shape of the pulse gear teeth changes due to corrosion etc., the period of the pulse signal increases. It is forbidden for deviations to occur. In this case, the detected wheel speed will have an error, and the anti-skisodo control that uses this as input information will lack accuracy.

For this reason, it is necessary to improve the machining accuracy of the pulse gear and use high-quality corrosion-resistant plating.
As a result, the anti-skid control device had to become expensive.

(Means for solving the problem) In order to solve this problem, the present invention, as conceptually shown in FIG.
A rotation sensor 3 that detects the passage of the teeth of a pulse gear 2 that rotates with the wheel 1 and emits a pulse signal, a wheel speed detection device 4 that determines the wheel speed from the period of the pulse signal, and an anti-clockwise sensor that uses this wheel speed as input information. The skid control device 5 includes a pulse cycle abnormality determining means 6 that determines whether the period of each pulse signal is abnormal by comparing it with the previous pulse period, and a pulse period abnormality determining means 6 that responds to a signal from the means when the pulse period is abnormal. The pulse cycle correction means 7 corrects the pulse cycle based on the relationship with the previous pulse cycle.

(Function) The pulse gear 2 rotates together with the wheels 1 while the vehicle is running.
During this period, each time a pulse gear tooth passes, the rotation sensor 3
Emit pulse signals. The period of this pulse signal corresponds to the wheel speed, and becomes shorter as the wheel speed increases. The wheel speed detection device 4 determines the wheel speed from this pulse period. At this time, the pulse period abnormality determination means 6 determines whether the period of each pulse signal is abnormal by comparing it with the previous pulse period, and the abnormal pulse period correction means 7 converts the abnormal pulse period into the previous period. The correction is made based on the relationship (for example, ratio) with Therefore, if the machining accuracy of the pulse gear is poor or the pulse gear teeth are corroded and the pulse signal is out of period,
This abnormal pulse period is corrected, and the wheel speed determined from the pulse period can be made accurate, and the operating accuracy of the anti-skid control device 5 which uses this wheel speed as input information can be maintained at a high level.

This eliminates the need to increase the processing accuracy of the pulse gear or the corrosion-resistant plating specifications to achieve this accuracy.
The wheel speed detection device and, by extension, the anti-skid control device can be made inexpensive.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows an embodiment of the present invention. In the figure, 10 is a wheel whose wheel speed is to be detected, 11 is a pulse gear that rotates together with this wheel, and 12 is a rotation sensor fixedly installed directly opposite the teeth 11a of the pulse gear 11. , 13 is a brake switch, 14 is a wheel speed detection device, and 15 is an anti-skid control device.

It is assumed that the rotation sensor 12 emits one pulse signal each time one pulse gear tooth 11a passes, and therefore continuously generates a pulse signal as shown in FIG. 3, for example, while the vehicle is running. The pulse periods t1 to t7 between these pulse signals become shorter as the rotational speed of the wheels 100 increases. Further, the brake switch 13 is a normally open switch, and is turned on when the brake pedal 16 is depressed to brake the vehicle.

The wheel speed detection device 14 uses the signals from the rotation sensor 12 and the brake switch 13 as input information and executes the control program shown in FIG. 4 to determine the wheel speed 1 of the wheel 10. It is assumed that normal anti-skid control is executed based on wheel speed ■1.

In the control program shown in FIG. 4, in step 20, an interrupt is executed every time the pulse signal from the rotation sensor 12 rises, and first, in steps 21 to 23, the number n of each interrupt, that is, each pulse signal, is determined, and the number n of each pulse signal is determined. 24, the human power instantaneous Th (3rd
(see figure) is stored in memory. Note that the above numbering uses numbers from n=1 to n=N (where N is the number of pulse gear teeth 11a). That is, until n=N is determined in step 22, the numbers 2 to N incremented in step 21 are numbered, and when it is determined that 'n>N, n=1 is returned to step 23.

In the next step 25, the brake switch 16 is ON or OFF.
It is determined whether the brake is in FF mode and the wheel speed does not change suddenly while the brake is off and the wheel acceleration/deceleration is almost constant.
Each pulse period 1. ．． The difference between t and the previous pulse period t is the previous pulse period t. -1 and the pulse period t before the previous one.

-2 (t, , -t, , -+ # L
-+-th-21. ', tr, #2tr, -+ jh
-2), each pulse period t, as follows. ' is the reference value S. "2jh-+ '-t,,-
It is determined whether it is normal or abnormal depending on whether the value is around 2' or not. That is, first, in step 26, each pulse period t. '= T, -
T, , and the previous pulse period t,, '= T,, -
T E2 and the pulse period before the previous time th-2' ” Tr
+-2Tr+-3 is calculated, and in the next step 27, the pulse period abnormality judgment reference value S,, = 2t,, -+ '-t
, , find -2'. In the next step 28.29, each pulse period 1. ．． is considered to be normal, first calculate rl, and then determine the period of each pulse t depending on whether this 1δ1 is greater than or equal to ε. ′ is abnormal or not, and if it is normal, the above δ is set to 0 in step 30, and this is changed to δ in step 31.
, and if it is abnormal, the calculated value δ in step 28 is set to δ in step 31.

In the next step 32, each pulse period 1h is calculated, and in step 33, this calculated value is added to 1+δ, (δ).

(see step 31)) to calculate each pulse period 1. .

(However, if the pulse period 1h is normal, δ = 1, so the pulse period 1. remains the calculation result of step 32)
do. In step 34, a constant k that takes into account the number of pulse gear teeth 11a and the radius of the wheel is used as the pulse period t of the above correction method. Divide by wheel speed■. is determined, and in the next step 35, the program returns to the main routine (not shown), and the control program shown in FIG. 4 is stopped until the next pulse signal is manually input from the rotation sensor 12.

Note that if it is determined in step 25 that braking is in progress, steps 26 to 31 are skipped and steps 32 to 35 are executed, and δ immediately before the braking is started. The wheel speed is determined while correcting the abnormal pulse period based on the following.

In addition, in the above embodiment, the ratio was used for abnormality determination and correction, but
Of course, a difference may be used instead of this.

(Effects of the Invention) As described above, the wheel speed detection device of the present invention is configured to determine an abnormality in the pulse period and correct the pulse period at the time of abnormality to contribute to calculation of the wheel speed. Even if a period shift occurs in the pulse signal due to corrosion of the pulse gear teeth, the wheel speed can be accurately detected, and anti-skid control can be performed with high precision using this as input information.

Also, for this reason, there is no need to increase the processing accuracy of the pulse gear or the corrosion-resistant plating specifications, and wheel speed inspection 9
Therefore, it is possible to reduce the cost of the anti-skid control device and, by extension, the anti-skid control device.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the device of the present invention, Fig. 2 is a system diagram showing an embodiment of the device of the present invention, Fig. 3 is a waveform diagram of a pulse signal output by the rotation sensor in the same example, and Fig. 4 is the same. It is a flowchart of a control program executed by a wheel speed detection device in an example. 1.10...Wheel 2.11...Pulse gear 3.12...Rotation sensor 4.14...Wheel speed detection device 5.15...Anti-skid control device 6...Pulse cycle abnormality determination Means 7... Pulse cycle correction means 13... Brake switch 16... Brake pedal Fig. 1 Fig. 2 Fig. 3

Claims (1)

[Scope of Claims] 1. A rotation sensor that detects passage of teeth of a pulse gear that rotates together with the wheel and generates a pulse signal, and a wheel speed detection device that determines the wheel speed from the period of the pulse signal. An anti-skid control device which receives input information as input information, comprising: pulse cycle abnormality determining means for determining whether the period of each pulse signal is abnormal from a comparison with a previous pulse period; A wheel speed detection device comprising: pulse period correction means for correcting an abnormal pulse period based on the relationship with the previous pulse period in response to a signal.