JPH0329603B2 - - Google Patents

Description

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

(Prior art) Conventionally, as a tire puncture detection device for a rail 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 (a) above that detects the tire contact length, even though the measurement time is wide, ranging from 10 to 200 ms, it is necessary to read a difference of about 20% 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 of detecting only 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.

Furthermore, since the trigger level for extracting the signal from the load detector is a factor for determination, the load level must be set to a sufficiently low value.

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 simple decrease in wheel load, and it is still not possible to accurately respond.

In addition, as shown in Japanese Patent Application Laid-Open No. 59-202913, which uses the combinational logic method of both formulas (a) and (b) above, a load signal from a load detector is received and the load signal is detected. There is also known a device that determines whether the waveform is caused by a normal tire or a flat tire. In this case, in order to start signal processing, it is necessary to determine the presence of a tire by using the load signal as a trigger at a certain level, so the level must be low enough to ensure operation in the event of a puncture. Must be set. However, when starting signal processing at a low trigger level, signal processing will start even if there is a foreign object other than the specified tire, such as a work trolley, inspection vehicle, worker, etc., and the waveform of the load signal will naturally be normal. Since the tires are different from the standard tires, false detections and alarms can occur, which can be a major problem. Furthermore, there is a risk of malfunction due to vibrations generated while the vehicle is passing. For these reasons, it is not possible to substantially lower the trigger level, making it difficult to ensure reliability and improve the accuracy of puncture detection.

(Purpose of the Invention) This invention was made to eliminate such conventional drawbacks, and it is possible to ensure reliability and high precision in panther detection by setting the trigger level, which is the basis of signal processing, to a sufficiently low value. The present invention provides a tire puncture detection device that is capable of realizing the following features and reliably prevents malfunctions caused by foreign objects.

(Structure of the Invention) This invention includes a load detector that detects the load caused by the pneumatic tires on both the left and right sides of the same shaft, and a signal from the load detector that is set at a first level or higher near the minimum load in the event of a tire puncture. a first signal generating means for generating a first signal, and a second level or higher set within a range of a signal from the load detector that is smaller than the minimum value of the peak load at the time of tire puncture and larger than the maximum load of the foreign object. The second signal to take out the second signal of
signal generating means; determining and display means for determining and displaying a tire puncture by processing the signal from the first signal generating means;
and a reset signal generation circuit that stops processing the first signal when no signal is generated.

In the above configuration, since signal processing is started with the first signal at a sufficiently low level, tire puncture detection can be performed reliably and with high accuracy, and the minimum value of the peak value of tire puncture can be detected. Since processing of the first signal is stopped when a larger signal is not generated, malfunctions can be reliably prevented.

(Example) In Fig. 1, 1 is a left side load detector that detects the load from, for example, the left tire among the left and right pneumatic tires on the same axis, and 2 is a right side load detector that detects the load from the right side tire. Both detectors 1 and 2 may be sensors that can extract load signals in time series, and usually use load cells, pressure-sensitive switches, piezoelectric elements, etc., and are installed on the tire rolling surface of the vehicle track. and use it. When the internal pressure of both tires is normal, both detectors 1 and 2 detect the tire contact length as shown in Figure 2 A and B.
Approximately similar waveform signals A and B are output with no significant difference in both t ₁ and t ₂ and load peak values p ₁ and p ₂ . 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. 2C to 2E 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 into the tire or coaxially attached does not yet come into contact with the detector 2, such as at the time of a puncture. Output signal B ₁ at this time is a normal signal (output signal of left side detector 1)
Compared to A, the tire contact length t ₂ is larger and the load peak value p ₂ is smaller. In addition, in D, 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 . A signal _B2 is shown, and E shows an output signal _B3 in which the load transmission by the auxiliary wheels further increases and the protrusion amount of the load peak value _p2 increases.

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 this synthesizer 3 is
It is shown in FIG. 3 corresponding to the figure. Figure 2 A, B
In the normal tire range, as shown in Fig. 3A and B, the tire contact lengths t ₁ and t ₂ and the load peak values p ₁ and p ₂ of the left tire side signal A and the right tire side signal B are slightly different from each other. Due to the difference, 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 FIGS. 2C to 2E where the right tire is punctured, waveform signals E, F, and G spanning both positive and negative sides are extracted as shown in FIGS. 3C to 3E.

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 these 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 composite waveform signals C and D in FIGS. 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, a composite waveform signal F of three pulse signals E ₁ , E ₂ , E ₃ , and D, one on the positive side and two on the negative side, is generated.
In the case of , a total of 4 pulse signals, 2 positive and 2 negative pulse signals
In the case of composite waveform signal G of F ₁ to F ₄ and E, positive side 2
A total of five pulse signals _G1 to _G5 , three on the negative side, are output.

As mentioned 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 transmitted to the logic section 14.
is sent to counters 6 and 7 through counters 6 and 7.
The total number of pulses counted at step 7 and then counted by the semi-constant device 8 as described above (the number of times the composite waveform exceeds the positive and negative reference values +L, -L) and the preset number of reference pulses (2) If the number of pulses exceeds this reference value (3 or more), it is determined that there is an abnormality (punk), and a reset signal (described later) is sent.
While Rs is being input, the above-mentioned abnormality signal is input from the determiner 8 to the display section 9 equipped with an indicator light and the like. Note that the determiner 8 determines that there is an abnormality when a pulse is output from both counters 6 and 7, and when a pulse is output from only one of the counters (as in the case of A and B in FIG. 4). is not determined to be abnormal even if the number of pulses is large.

Further, output signals A and B from the load detectors 1 and 2 in FIG. 1 are also sent to trigger circuits 11 and 12,
When this signal exceeds a predetermined trigger level _L1 , pulse signals a and b shown in FIGS. 5A and 5B are output. This level (first level) L ₁ is set to a small value within a range that is not affected by errors in the zero points of the load detectors 1 and 2 in order to improve detection accuracy. These pulse signals (first signals) a and b are
The reset signal R is input to the OR circuit 13 and 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. 6, 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 this signal.
7, 18, first AND circuits 19, 20 which input the output signals of the NOT circuits 17, 18 and the OR circuits 15, 16, and the AND circuit 1.
It consists of second AND circuits 21 and 22 which AND the output signals of 9 and 20 and the reset signal. Note that the output signals of the second AND circuits 21 and 22 are also input to the OR circuits 15 and 16. As a basic principle, the logic unit 14 calculates the mutual behavior of the synthesized waveforms: (a) Exceeding positive reference value + L → Exceeding negative reference value - L (B) Exceeding negative reference value - L → Exceeding positive reference value + L It's something to count. That is, when a signal is generated only from the comparator 4, the signal is sent to the AND circuit 19 through the OR circuit 15, and at this time, since the AND circuit 19 does not have a signal from the comparator 5, The NOR circuit 17 side is turned on and a signal is sent to the first AND circuit 21, and since the reset signal R is also sent here, a signal is sent to the counter 6. Similarly, if a signal is generated only from the comparator 5, the signal is sent to the counter 7.

The output signal of the logic section 14 is transmitted to the counters 6 and 7.
and is taken into the determination unit 8 via the addition circuit 23. 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 left depending on whether the number of input pulses on the positive or negative side is greater.

The signals A and B from the detectors 1 and 2 are also sent to trigger circuits 31 and 32, and when these signals exceed a predetermined trigger level _L2 , the signals are sent to an AND circuit 33. As shown in Fig. 7, this level (second level) L ₂ is the expected minimum value of the load peak value at the time of a puncture (peak values of signals B ₁ and B ₂ in Fig. 2) and the foreign object. It is set midway between the maximum load generated by the above
A signal of L ₂ or more (second signal) triggers the trigger circuit 31,
32, the AND circuit 33
A signal P is sent to the reset signal generation circuit 34 from which a reset signal Rs is sent to the comparator 24.
and sent to the determiner 8. The reset signal R from the OR circuit 13 is also input to the reset signal generating circuit 34.

The reset signal generating circuit 34 is constructed as shown in FIG. That is, an OR circuit 35 whose one input is the signal P from the AND circuit 33;
an AND circuit 36 which receives this signal as one input;
An off-delay 37 that receives this signal X, an OR circuit 38 that receives this signal Y as one of its inputs, an AND circuit 39 that receives this signal as one of its inputs, and a NOT circuit that receives the signal from the OR circuit 13 as its input. 40, the output of this NOT circuit 40 is input to the other AND circuit 39, and the AND circuit 39
The output of the AND circuit 36 is input to the other of the OR circuit 38, and the output of the AND circuit 36 is input to the other of the OR circuit 35. The off-delay 37 is for holding the operation of the logic element for a certain period of time, and may be constructed using a circuit element using a capacitor and a resistor or an off-delay timer as hardware. Note that the holding time td is only necessary to operate the next stage logic element, and is usually several msec to several + msec.

FIG. 9 shows the operation of the reset signal generation system. Upon detection of a tire, a reset signal R exceeding the trigger level of _L1 is generated, and then a signal P based on the trigger level of _L2 is generated. This signal R and P
When this happens, the off-delay 37 is turned on by the signal X from the AND circuit 36, and its output side is also turned on immediately, and the output Y is sent to the OR circuit 38. At this time, since no signal is sent to the other input side of the AND circuit 39 by the NOT circuit 40, no output is generated from the AND circuit 39. When the tire passes and R turns off, the knot circuit 40
The other side of the AND circuit 39 is turned on by remains on. Therefore, the AND circuit 39 is turned on and the reset signal Rs is output, and this output time
The comparator 24 and addition circuit 23 process the signals from the counters 6 and 7 by Ts. In this way, even if there is a detection signal of level L ₁ or higher, the detection signal indicating the passing of a tire (signal exceeding level L ₂ )
Since this is processed as a tire passing signal only when this occurs, malfunctions due to foreign objects can be reliably prevented.

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

As for which axle of the vehicle the tire puncture is present on, for example, the number of passing axles is counted by a counter based on the tire detection signals of the detectors 1 and 2, and this count signal is displayed on the display section 9. This can be determined by sending the item. 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.

FIG. 10 shows another embodiment of the invention, in which the same device is constructed separately for left and right tires. Reference numeral 1 denotes a load detector that detects the load caused by the left or right pneumatic tire, and the load signal from this load detector 1 is shown in FIG. In the figure, signal A shown at A is a signal when the tire internal pressure is normal, and signals _B1 to _B3 shown at B to D are signals when the tire internal pressure is abnormal (flat tire). 11th
Abnormal signal B ₁ in Figure B indicates an output signal when the internal pressure of the tire is maintained at a level such that the auxiliary wheel built into the tire or coaxially attached does not yet come into contact with the detector 1, such as at the beginning of a puncture. ing. The abnormal signal B ₁ at this time has a longer tire contact time Tb and a smaller load peak value Pb than the normal signal A. Ta is the tire contact time of normal signal A;
Pa indicates the load peak value of a normal tire. Also,
The abnormal signal B ₂ shown in FIG. 11C indicates a state in which the internal pressure has decreased and the auxiliary wheel hits the detector 1, causing the load peak value Pb to protrude at the middle part of the tire passage. The abnormal signal _B3 indicates a signal in a state where the load transmission by the auxiliary wheels further increases and the protrusion amount of the load peak value Pb increases.

Here, the common phenomena for each of the abnormal signals B ₁ to _{B 3} are: () The tire contact time Tb becomes longer than the normal contact time Ta () In the event of a tire puncture, the training wheels do not bear the load yet. The maximum value of tire internal pressure (abnormal tire internal pressure level) that corresponds to the load peak value Pb at signal B ₁ in Fig. 11B, the duration time t ₃ of the signal of L ₃ or more is shorter than the duration t ₃ in the normal case. There are two points to be mentioned: [The abnormal signal _B1 in FIG. 11B becomes zero]. Therefore, by understanding this load waveform characteristic unique to the time of a tire blowout, it is possible to detect a tire blowout.

Therefore, in this device, in order to grasp the above characteristics, the load signal from the load detector 1 is first sent to both the first and second trigger circuits 5 in FIG.
2, 53, and here the above tire load detection level L ₁ or higher signal and tire internal pressure abnormal level L ₃ are input.
The signal is divided into the above signals, and the duration of each of these signals is measured by timers (time measuring means) 54 and 55.

That is, the trigger level of the first trigger circuit 52 is a basic level indicating that the tire load has been detected.
It is set to _L1 . Therefore, regardless of whether the tire internal pressure is normal or abnormal, the timer 54 is triggered if there is a tire load detection signal. On the other hand, the trigger level of the second trigger circuit 53 is set to the tire internal pressure abnormality level _L3 , and among the signals at the basic level _L1 or above (hereinafter referred to as basic signals), the signal at this abnormal level _L3 or above (hereinafter referred to as a high level signal) only triggers the timer 55.
In this way, the timers 54 and 55 measure the durations t ₁ and t ₃ of the basic signal and the high level signal. FIGS. 12A to 12D show the length of time to be measured, and the timers 54 and 55 output corresponding output signals in the form of voltages and time counts. These time lengths correspond to the load signals A and B ₁ -B ₃ of FIGS. 11A-D. These output signals, that is, the measured signal durations (hereinafter referred to as measurement times) t ₁ , t ₃
The signal is input to the calculation unit 56, where the ratio of both measurement times t ₁ and t ₃ , that is, the measurement time t ₁ of the basic signal
The ratio of the measurement time t ₃ of the high level signal to that of the high level signal is calculated.

This measurement time ratio t ₃ /t ₁ has a maximum value close to 1 in the case of the normal signal A in FIG. 11A, and becomes small in the case of the abnormal signals B ₁ to B ₃ . That is, the first
In the case of abnormal signal B ₁ in Figure 1B, the measurement time t ₃ of the high-level signal itself becomes zero (a value close to zero depending on the tire), and the value of the above ratio t ₃ /t ₁ becomes zero (or In the case of abnormal signals B ₂ and B ₃ of C and D, the value is larger than this, but much smaller than in the normal case (according to experiments, it is 0.2 to 0.3).

Further, the signal from the detector 1 is sent to a trigger circuit 41, and this signal is set to a predetermined trigger level.
If the signal exceeds L ₂ , the signal is output to the AND circuit 43.
sent to. Similarly, signals from load detectors on the opposite left and right sides (not shown) are also sent to the other side of the AND circuit 43 through the trigger circuit. this level
Similarly to the above, L ₂ is also set to be between the expected minimum value of the load peak values at the time of a puncture shown in FIG. 7 and the maximum load generated by a foreign object. When signals equal to or more than _L2 are sent from both trigger circuits, the AND circuit 43 sends the signal P to the reset signal generation circuit 44, from which the reset signal Rs is sent to the comparator 57, and only during that time. Let the comparator 57 process.

The output value (t ₃ /t ₁ value) of the calculation unit 56 is input to the comparator 57, where it is compared to a preset reference value S.
(for example, 0.3 or more), and the output value is compared with the reference value S
If it is smaller, a signal indicating an abnormality in the tire internal pressure is inputted from the comparator 57 to the display section 8 equipped with an indicator light, etc., and a puncture of the tire is displayed.
Note that the signal processing by the comparator 57 is also performed only while the reset signal Rs is being input, as described above, and the reset signal Rs is also processed as shown in FIGS.
The input is similar to that shown in the figure.

The above functions can also be performed on computer software, and an example of the processing in that case is shown in Part 1.
It is shown in Figure 3. In the same figure, the axis count N is set to O in step _S1 due to the waveform input of the next train, and it is determined in step _S2 whether the signal exceeds the level _L1 or is _distorted . ₁
Start timing, then level at step S ₄ .
Determine whether it exceeds L ₂ or is distorted. If it exceeds level L ₂ , it is a specified vehicle, so in step S ₅ the axes are counted and N=N+1, and in step S ₆ it is determined whether the level has fallen below level L ₁ or it is distorted. If so, the vehicle has passed, so step S ₇
The time measurement at _t1 is stopped and the train passing detection process or puncture detection process is performed. In addition, step S ₂
If you do not want to exceed level L ₁ , proceed to step S ₂ .
Repeat the process. Also level L ₂ at step S ₄
If it does not exceed level L1, it is not the specified vehicle, so in step _S8 it is determined whether it has fallen below level _L1 or is distorted.
If it has not decreased, the process returns to step _S4 ; if it has decreased, the process is reset in step _S9 , and the process returns to step _S2 . The above method has the advantage that off-delay is unnecessary and processing can be performed using YES/NO decision logic.

(Effects of the Invention) As explained above, since the present invention starts signal processing with the first signal at a sufficiently low level, tire puncture detection can be performed reliably and with high precision. Moreover, since the processing of the first signal is stopped when the second signal larger than the minimum tire puncture peak value is not generated, malfunctions can be reliably prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of this invention.
Figures 2 A to E are output waveform diagrams of the load detector, Figures 3 A to E are composite waveform diagrams corresponding to the outputs, and Figures 4 A to E are output waveform diagrams from the positive and negative level comparators.
Figure 5 is a circuit diagram of the logic section in Figure 1, Figure 6A
-C are output waveform diagrams of the trigger circuit, Fig. 7 is an explanatory diagram of high and low trigger levels, Fig. 8 is a circuit diagram of the reset signal generation circuit of Fig. 1, and Fig. 9 is an explanatory diagram of the operation of the reset signal generation system. , FIG. 10 is a block diagram showing another embodiment of the present invention, FIGS. 11-D are output waveform diagrams of the detector in this device, and FIG. 12A
~D is an explanatory diagram of the signal corresponding to the output, the 11th
FIG. 3 is a flowchart showing an example of processing the detection signal on software. 1, 2...Load detector, 9...Display section, 11,
12, 31, 32, 41...Trigger circuit, 23
...Determiner, 24, 57...Comparator, 34, 44
...Reset signal generation circuit, _L1 ...1st level,
_L2 ...Second level, R, Rs...Reset signal.

Claims (1)

[Claims] 1. A load detector that detects the load caused by the pneumatic tires on both the left and right sides of the same shaft, and a first device that extracts a first signal of a first level or higher set around the minimum load in the event of a tire puncture among the signals from this load detector. and a second signal generating means for extracting a second signal of a second level or higher set within a range smaller than the minimum value of the peak load at the time of tire puncture and larger than the maximum load of the foreign object among the signals from the load detector. a signal generating means for processing the signal from the first signal generating means to determine and display a tire puncture; 1. A tire puncture detection device comprising: a reset signal generation circuit for stopping processing of one signal.