JPH0418561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tire puncture detection device for a vehicle running on a track with pneumatic tires.

(Prior art) Conventionally, as a tire puncture detection device for a railway vehicle, (a) as shown in Japanese Patent Publication No. 58-51483, for example, an increase in the contact length of the tire tread portion caused by a decrease in the internal pressure of the tire is used. (b) A method that detects changes in the tire load peak value is known.

However, in the case of the method of detecting the tire contact length in (a) above, even though the measurement time is wide, ranging from 10 to 200 ms, it is necessary to read a difference of about 20% of that to detect a drop in internal pressure. Load detectors and amplifiers are required to have high accuracy, high resolution, and high stability. This has the drawback that the device is complicated and expensive. Furthermore, with this method, which only detects the tire contact length, it is difficult to determine whether an increase in the contact length is due to a puncture or an increase in wheel load, making it impossible to respond accurately.

On the other hand, in the method (b) of detecting only the load peak value, there is a risk of confusing a tire blowout with a mere decrease in wheel load, and it is still not possible to accurately respond.

In addition, even when using the combinational logic method of both (a) and (b) above, if the tire has a built-in or coaxially attached auxiliary wheel that becomes a temporary running wheel in the event of a puncture, the internal pressure of the tire itself Even if the load decreases, the load peak value of the output signal of the detector may show a normal range depending on the auxiliary wheels, and in principle, accurate response cannot be performed.

(Object of the Invention) Therefore, the present invention provides a tire puncture detection device that is simple in principle and configuration, and is inexpensive, yet can accurately detect tire punctures regardless of the tire condition, such as the size of the wheel load. This is what we intend to provide.

(Structure of the Invention) The present invention is characterized by a pair of load detectors that detect the load due to the pneumatic tires on both the left and right sides of the same shaft, and a waveform that combines the signal waveforms from both the detectors so that they are subtracted. a synthesizer; a comparator that compares the positive and negative values of the synthesized waveform by the waveform synthesizer with preset positive and negative reference values; and a tire puncture detector comprising: a counter that counts the number of times the negative reference value is exceeded; and a determiner that determines an abnormality and outputs an abnormal signal when the count by the counter exceeds a predetermined number. equipment.

(Example) FIG. 1 shows the basic configuration of this device. In the figure, 1 is a left side load detector that detects the load from, for example, the left tire of the left and right pneumatic tires on the same axis, and 2 is a right side load sensor that detects the load from the right side tire. Sensor 2 may be any sensor that can extract load signals in time series, and is usually used by installing a load cell, pressure-sensitive switch, piezoelectric element, etc. on the tire rolling surface of the vehicle track. Both detectors 1 and 2 detect a large difference in tire contact lengths t ₁ and t ₂ and load peak values p ₁ and p ₂ as shown in Figure 2 A and B when the internal pressures of both tires are normal. Outputs substantially similar waveform signals A and B without any difference. On the other hand, in the case of an abnormal (flat) tire, a large change occurs in the detection signal on the abnormal tire side. FIGS. 2A to 2H show the case where the output signal of the right side detector 2 changes due to a puncture of the right side tire. C shows the output signal B ₁ in a state where the internal pressure of the tire is maintained to such an extent that the auxiliary wheel built in or coaxially attached to the tire does not yet come into contact with the detector 2, such as at the time of a puncture. The output signal B ₁ at this time has a larger tire contact length t ₂ and a smaller load peak value p ₂ than the normal signal (output signal of the left side detector 1) A. In addition, the internal pressure decreases further and the auxiliary wheel hits the detector 2, and as a result, the load peak value _p2 stands out in the middle of the tire passage, and the output almost corresponds to the normal peak value _p1. indicates signal B ₂ ,
E is an output signal B ₃ in which the load transmission by the auxiliary wheel further increases and the protrusion amount of the load peak value p ₂ increases.
It shows.

The output signals from both detectors 1 and 2 are as follows:
The waveform synthesizer 3 shown in FIG. 1 synthesizes the signals in a subtractive manner. The synthesized waveform by the synthesizer 3 is
It is shown in FIG. 3 corresponding to the figure. In the tire normal range shown in Fig. 2 A and B, as shown in Fig. 3 A and B, the tire ground contact lengths t ₁ and t ₂ and the load peak value p ₁ of the left tire side signal A and the right tire side signal B are , p ₂ , in the case of this example in Figure 2,
Signals C and D are taken out almost only on the negative side. On the other hand, in the abnormal region shown in FIG. 2, where the right tire is punctured, waveform signals E, F, and G spanning both positive and negative sides are extracted, as shown in FIG. 3, parts C to H.

The output signals C to G from the waveform synthesizer 3 are input to the positive and negative level comparators 4 and 5 shown in FIG. +L, -L), and if the composite waveform signal exceeds the reference values +L, -L,
As shown in FIG. 4, a pulse signal corresponding to the exceeded portion (number of times) is output. That is, the third
In the case of the composite waveform signals C and D shown in Figures A and B, two negative side pulse signals C ₁ and C ₂ and D ₁ and D ₂ are output. In the case of the composite waveform signal E shown in FIG. 3C, which is a puncture signal, the composite waveform signal F of three pulse signals E ₁ , E ₂ , E ₃ , and 2, one on the positive side and two on the negative side, is used. In this case, 2 positive and 2 negative pulse signals, total 4 pulse signals F ₁
~F ₄ , in the case of composite waveform signal G in E, two positive side,
A total of five pulse signals _G1 to _G5 , three on the negative side, are output.

Even if the tires are in the normal range, if the timing at which the tires on both sides step on the detectors 1 and 2 on both sides is off due to, for example, the inclination of the vehicle body or the inclination of the wheels themselves, then As shown in FIG. 6A and B, composite waveform signals C' and D' spanning the positive and negative sides are extracted by the time-shifted waveform signals A and B, and the comparator 4,5
As output signals from the C' 1 , C' ₂ and C' ₂ positive and negative pulse signals, as shown in Figure 7 A and B,
D′ ₁ and D′ ₂ are output.

As described above, when a tire is punctured, a total of three or more pulse signals are output from the positive and negative level comparators 4 and 5. This pulse signal is counted by counters 6 and 7, and then determined by a determiner 8 to determine the total number of pulses counted (if the composite waveform is positive or not).
The number of times the negative reference value +L, -L is exceeded) is compared with a preset reference pulse number (2), and if the number of pulses exceeds this reference value (3 or more), it is determined to be abnormal (punk). After the determination, an abnormality signal is input from the determination device 8 to the display unit 9 equipped with an indicator light and the like. Note that the determiner 8 determines that there is an abnormality when pulses are output from both counters 6 and 7, and when pulses are output from only one of the counters [such as cases A and B in Figure 4]. is not determined to be abnormal even if the number of pulses is large.

On the other hand, the pulse signals from both comparators 4 and 5 are input to a latch circuit 10, where the pulse signal input first or last is held. That is, the latch circuit 10 determines whether the first or last pulse is from the positive or negative level comparators 4 and 5. For example, in the case of the pulse signal shown in FIG. It is output as a pulse signal H shown in FIG. The output signal of the latch circuit 10 and the abnormality determination signal from the determiner 8 are taken into the display section 9, and the tire puncture and whether the flat tire is left or right are displayed.

As for which axle of the vehicle the flat tire is located on, for example, the number of passing axles is counted by a counter based on the tire detection signals from the detectors 1 and 2, and this count signal is sent to the display section 9. It can be determined by Further, the counters 6, 7 and the determiner 8 can be reset based on the tire detection signals of the detectors 1, 2, on the condition that the left and right tires have completed passing.

Incidentally, although the above embodiment has been described on the assumption that information is processed in an analog manner, it is of course possible to process information in a digital manner using a microcomputer or the like. Specifically, an A/D converter is inserted in either the load detectors 1 and 2, the waveform synthesizer 3, or the comparators 4 and 5 in the configuration shown in FIG. 1, and the subsequent processing is performed by software. You can have it done above.

Further, when many vibration components are superimposed on the synthesized waveform by the waveform synthesizer 3, the apparatus configuration shown in FIG. 9 can be adopted. In FIG. 9, only the differences from FIG. 1 will be explained. Reference numerals 11 and 12 are trigger circuits that embody the above-mentioned reset method and counting method.
When the output signals A and B from the load detectors 1 and 2 in the figure exceed a predetermined trigger level,
Pulse signals a and b shown in (b) are output. These pulse signals a and b are input to the OR circuit 13,
The reset signal R shown in FIG. 12 is output, and this reset signal R is input to the logic section 14 together with the output signals of the comparators 4 and 5.

As shown in FIG. 10, the logic section 14 includes an OR circuit 1 which receives the output signals of the comparators 4 and 5 as one input.
5, 16, and a knot circuit 1 that inverts the same signal.
7, 18, first AND circuits 19, 20 into which the output signals of the NOT circuits 17, 18 and the OR circuits 15, 16 are input;
20 and the reset signal are ANDed. Note that the output signals of the second AND circuits 21 and 22 are also input to OR circuits 15 and 16.
As a basic principle, this logic unit 14 counts the mutual behavior of the composite waveform: (a) Exceeding the positive reference value + L → exceeding the negative reference value - L (B) Exceeding the negative reference value - L → exceeding the positive reference value + L This makes it possible to ignore vibration components near one of the reference values. Therefore, malfunction of the device due to vibration components can be prevented.

The output signal of this logic section 14 is taken into the determiner 8 via the counters 6 and 7 and the adder circuit 3 shown in FIG. The outputs of the counters 6 and 7 and the reset signal R are input to a comparator 24, and it is determined whether the flat tire is on the right or the left depending on which side, positive or negative, has a greater number of input pulses.

Note that this type of vehicle uses rubber tires, so if the track execution accuracy is good, there will be less vibration components.In addition, if the composite waveform is passed through a low-pass filter, the configuration shown in Figure 1 can be used in practice. It becomes something that does not exist.

Furthermore, the present invention can also be applied to tire vehicles that do not have auxiliary wheels. In this case, tire puncture is determined based on the signal C in FIGS. 2 to 4.

On the other hand, as another means for determining whether a flat tire is left or right, for example, as shown in Figure 4 C and D, the pulse interval on the flat tire side is measured based on the phenomenon that the pulse interval becomes wider. However, the longer one may be determined to be the puncture side. However, distinguishing between the left and right sides of a punctured tire is only for the purpose of facilitating later inspection and repair, and in terms of vehicle operation, it is actually sufficient to detect whether or not there is an abnormality in the tire. It is not necessarily necessary to distinguish between the left and right sides of a flat tire.

(Effects of the Invention) As described above, the present invention combines the waveforms obtained by the tires on both the left and right sides of the same shaft in a subtractive manner, and detects tire abnormalities based on characteristic changes in the combined waveform. This is because it determines whether the tire is punctured or not.
Although the principle and structure are simple and inexpensive, tire punctures can be accurately detected regardless of the tire condition such as the size of the wheel load.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the device according to the embodiment of the present invention, Fig. 2 is an output waveform diagram of the load detector, Fig. 3 is a composite waveform diagram, and Fig. 4 is the output from the positive and negative level comparators. Waveform diagrams, Figures 5 to 7 are waveform diagrams corresponding to Figures 2 to 4 A and B when the tire detection signal deviates in time in the normal tire range, and Figure 8 shows the left and right side of a flat tire. 9 is a block configuration diagram of a device according to another embodiment of the present invention, FIG. 10 is a circuit configuration diagram of a logic section in the same device, and FIG. The output waveform diagram of the trigger circuit in the device, FIG. 12, is a waveform diagram of the reset signal based on this trigger output. 1, 2...Load detector, 3...Waveform synthesizer,
4, 5... Positive and negative level comparators, 6, 7... Counters, 23, 24... Counters, 8... Determiners.

Claims (1)

[Claims] 1 A pair of load detectors that detect the load due to the pneumatic tires on both the left and right sides of the same axis, a waveform synthesizer that synthesizes the signal waveforms from both detectors so that they are subtracted, and a and a comparator that compares the negative value with preset positive and negative reference values, and a counter that counts the number of times the positive and negative values of the composite waveform, which is the output signal from this comparator, exceed the reference values. and a determiner that determines an abnormality and outputs an abnormality signal when the number counted by the counter exceeds a predetermined number.