JPH0769246B2 - Leakage position detection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak position detecting device for detecting a leak position of a liquid when the liquid leaks from equipment for transporting or storing a liquid.

(Prior Art) Conventionally, when a liquid such as hot water or a chemical liquid is transported through a pipeline, an accident may occur in which the liquid leaks from the pipeline. In order to detect the position of the leakage accident. In addition, various leak position detecting devices have been proposed so far. This type of liquid leakage position detection device has, for example, a detection portion including a power supply and a comparison resistor (reference resistor) and a sensor portion including a sensor line and a signal line as main components, and at that time, Some resistors and sensor lines are connected in series.

In the sensor part of this liquid leakage position detection device, for example, a method of detecting the position by measuring the resistance value of the sensor wire from the starting point of the sensor wire to the leakage point of the liquid by an absolute value, in other words, the absolute value of the voltage drop is used. In this case, when it is necessary to greatly change the length of the sensor wire depending on the construction and arrangement of the leak position detecting device, the same line up to that time used for the leak detecting part to detect the leak position. The comparative resistor is relatively inferior in the detection accuracy of the leak position, and it is necessary to change the comparative resistor in order to maintain the detection accuracy. There is an annoying problem of having to change.

Furthermore, as long as measurement is performed using this comparison resistor, the resistance value of the sensor wire used for position detection is always constant, in order to prevent errors in position detection and to prevent variations in manufacturing. Must be kept at a value.

Also, the resistance value of the sensor wire used for position detection always needs to be maintained at a constant value, which is the same for temperature. Therefore, select a material whose resistance change due to temperature is very small. However, there is also a problem in that it is restricted by the material of the sensor wire used.

At this time, if the liquid leakage position detecting device employs a constant current circuit, there may be a problem that the device is out of the constant current control range, and it may be necessary to change the current value or the like.

Furthermore, in the case of a constant current circuit, the power supply output changes greatly depending on the conductivity of the liquid to be measured, and especially in the case of a liquid with a low conductivity, the resistance at the leakage point of the liquid increases and the power supply capacity increases. Things are needed.

On the other hand, a so-called Murray loop type leak position detecting device using a Wheatstone bridge, that is, a leak position that detects the position by measuring the ratio of the total length of the sensor part and the leak point. In the detection device, since the resistance of the leak portion to be measured at the leak point is larger than the resistance value of the sensor line, the measurement voltage applied to the bridge becomes considerably smaller than the power supply voltage, and the accuracy deteriorates. This tendency is particularly pronounced for liquids whose conductivity to be measured is low.

(Problems to be Solved by the Invention) The present invention has been made in view of the above points, and a first object thereof is to provide a unit length of a sensor wire arranged to detect a leak position of a liquid. (EN) Provided is a leak position detecting device that can easily and easily measure a leak position without deteriorating the detection accuracy of a leak position even if the resistance value or the total resistance value changes. Is.

A second object of the present invention is to provide a liquid leakage position detecting device capable of always measuring with a constant accuracy even if the resistance value of the sensor wire changes due to manufacturing or the like or the resistance value of the sensor wire changes due to temperature or the like. Is to provide.

A third object of the present invention is to provide a liquid leakage position detecting device which can always measure with a constant accuracy even if the conductivity of the liquid to be measured whose leakage is measured changes.

A fourth object of the present invention is that even if a signal such as an undesired voltage is superimposed on the sensor line used to measure the liquid leakage position, this signal can be canceled and there is no measurement error. A liquid position detecting device is provided.

A fifth object of the present invention is to provide an abnormality occurrence position detection device capable of detecting and displaying the abnormality occurrence position, for example, when an abnormality occurs due to pressure, temperature, light, gas, etc. in the system. Is.

(Means for Solving the Problems) The above object is achieved by the liquid leakage position detection device of the present invention. That is, in summary, the present invention provides a sensor portion that outputs a signal proportional to the distance of a leak point when a leak of a liquid is detected, an oscillator circuit that generates a clock signal,
An up / down counter to which the clock signal is input by a predetermined timing signal issued from a timing circuit, a digital / analog converter to which an output signal from the up / down counter is input, and a counter counted by the up / down counter. A display for displaying a numerical value, an output signal from the digital / analog converter, and an output signal of the sensor portion are input, and these signals are compared to determine the up count and down count of the up / down counter. The liquid leakage position detecting device includes a comparator for performing the operation and a power source for applying a constant rectangular wave signal to the sensor portion and the digital-analog converter.

(Operation) According to the liquid leakage position detection device of the present invention, the sensor portion is
When a leaked liquid is detected, it is configured to output a signal as a ratio of a signal applied to the entire length of the sensor to a signal applied to the distance to the leak point.
Even if the length of the sensor wire arranged to detect the leak position of the liquid changes, it is possible to easily and easily measure with constant accuracy without deteriorating the detection accuracy of the leak position. At the same time, even if the resistance value of the sensor wire changes due to temperature etc., it is possible to always measure with a constant accuracy, and further, even if the conductivity of the liquid to be measured for measuring leakage changes,
It is possible to measure with constant accuracy.

(Example) Hereinafter, the present invention will be described based on an example with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory view of an embodiment of the liquid leakage position detecting device according to the present invention.

Referring to FIG. 1, there is shown a liquid leakage position detecting device 10 of the present invention, which has a power source 11 and a sensor portion 12 connected in parallel with the power source 11. ing. Here, the power supply 11 is, for example, a power supply for applying a rectangular wave voltage having a frequency of 0.5 Hz to the sensor portion 12,
Reference numeral 12 includes a signal line 12a, a resistance line 12b and a suction line 12c, and this sensor portion 12 is proportional to the voltage applied from the power source 11 according to the position of the leak point when the leaked liquid is detected. It is configured to generate an output voltage (in this embodiment, the output voltage is proportional to the length of the resistance wire up to the leak point). That is, when the sensor portion 12 detects a leaked liquid, the resistance line length up to the leak point (distance to the leak point) with respect to the voltage applied to the entire sensor length.
Since a signal is output as the ratio of the voltage applied to the output terminal, a voltage proportional to the distance of the leak point is output.

One end of the sensor portion 12 is connected to a reference voltage terminal of an external reference voltage application type digital-analog converter 13, and the other end thereof is grounded. When the liquid leaks in the sensor portion 12, the sensor output voltage is generated from the sensor portion 12, and the sensor output voltage is input to the high impedance conversion circuit 14. Reference number 15
Is an up / down counter. The up / down counter 15 outputs a digital signal to the digital-analog converter 13 and also outputs a digital signal to the display 16.

The output signal of the high impedance conversion circuit 14 is input to the non-inverting input terminal of the comparator 17, and this comparator 17
The inverting input terminal of the
The output signal from 13 is input. This comparator 17
Compares the sensor output value input via the high impedance conversion circuit 14 with the output value of the digital-analog converter 13.

The output signal of the comparator 17 is sent to the one end side input of the AND circuit 19, and is also sent to the one end side input of the AND circuit 21 via the inverter 20.

Timing circuits are connected to the other inputs of the AND circuits 19 and 21.
A clock signal generated from the oscillation circuit 23 is input via 22. These and circuits 19
The output signals of 21 and 21 are up / down counters respectively.
It is configured to be input to 15 up-counting side and down-counting side. Here, the timing circuit 22 inputs the clock signal generated from the oscillation circuit 23 to the other end side inputs of the AND circuits 19 and 21 in accordance with the timing of the voltage applied from the power supply 11 and the AND circuits 19 and 21. The timing signal is generated so that the clock signal is applied to the other end side input.

The operation of the above-described embodiment configured as described above will be described below.

Now, when the liquid leakage position detecting device of the present invention having the above-mentioned configuration is in an operating state, that is, the rectangular wave voltage from the power source 11 is applied to the sensor portion 12,
When a liquid leaks in the sensor portion 12 while being applied to the reference voltage terminal of the analog converter 13, an output signal corresponding to the leak position of the liquid, that is, a leak point of the leak point is generated through the suction line 12c of the sensor portion 12. An output voltage proportional to the distance is input from the sensor portion 12 to the non-inverting input terminal of the comparator 17 via the high impedance conversion circuit 14, while the inverting input terminal of the comparator 17 is connected to the digital input terminal.
The output voltage from the analog converter 13 is input. The output voltage from the digital-analog converter 13 is set to output a predetermined voltage value according to the count value output from the up / down counter 15.

Here, the count value output from the up / down counter 15 to the digital / analog converter 13 is the oscillation circuit 23
The clock signal generated from the above is input to the up / down counter 15 via the AND circuits 19 and 21 at a predetermined timing generated from the timing circuit 22. In this embodiment, the clock signal is input to the up / down counter 15 with the pulse width on the plus side of the rectangular wave voltage generated from the power supply 11 as the timing. Then, the comparator 17 compares these output signals.

At this time, if the sensor output voltage from the sensor portion 12 input to the comparator 17 via the high impedance conversion circuit 14 is higher than the output signal of the digital-analog converter 13, the output signal of the comparator 17 is oscillated. The clock signal from the circuit 23 is input to the up side of the up / down counter 15 via the AND circuit 19, and as a result, it operates so as to increase the set value of the digital / analog converter 13.

Thus, when the analog signal output from the digital-analog converter 13 becomes larger and becomes larger than the sensor output voltage input to the comparator 17, the comparator 17 outputs an inverted signal, and the inverted signal is output by the inverter.
20 via the AND circuit 21 together with the clock signal from the oscillation circuit 23, and is input to the down side of the up / down counter 15. As a result, the digital / analog converter 13
Operates to reduce the set value of.

In this way, the comparator 17 compares and controls the output signal from the digital-analog converter 13 with respect to the sensor output voltage, and as a result, the clock signal input to the digital-analog converter 13 from the up / down counter 15 is output. When the up / down counter 15 is controlled to alternately go up and down repeatedly,
The liquid leakage position is determined to be the measurement position, the output signal of the up / down counter 15 at this time is input to the display 16, and the liquid leakage position is displayed. The applied voltage of the power supply 11 is set to 0.
The rectangular wave voltage of 5 Hz is used because it is effective in canceling the polarization phenomenon of the leaked liquid.

Next, another embodiment of the present invention will be described with reference to FIG. Hereinafter, the same parts as those in the embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. The embodiment shown in FIG. 2 is substantially the same as the embodiment shown in FIG. 1 except that the embodiment shown in FIG. 1 is different from the embodiment shown in FIG. Another difference is that a polarization voltage correction circuit 25 is added to the next stage of the high impedance conversion circuit 14.

Now, the scale adjustment amplifier 18 described above will be described.

Now, consider the case where the output value of the digital-analog converter 13 is adjusted to the scale value of the output signal of the sensor portion 12.

The sensor applied voltage applied from the power source 11 to the sensor portion 12 is E, the sensor output voltage is V, and the sensor output count is x (0 to 0).
1), the sensor output voltage V = Ex. On the other hand, the applied voltage applied to the digital-analog converter 13 is E as in the sensor portion, the output value of the digital-analog converter 13 is y, the output coefficient of the digital-analog converter 13 is x (0 to 1), When the scale adjustment coefficient is z, the output value y of the digital-analog converter 13 becomes y = Exz. Here, x is a sensor output coefficient or an output coefficient of the digital-analog converter 13, which is operated by the circuit so as to have the same value. Therefore, the relation of y = Vz is established. As a result, the output value of the digital-analog converter 13 is obtained by multiplying the sensor output voltage by the scale adjustment coefficient. Therefore, the scale adjustment can be performed by adjusting the scale adjustment coefficient z.

Next, the polarization voltage correction circuit 25, when a signal such as a polarization voltage generated at the time of leak detection or some undesired voltage is superimposed on the sensor output signal, the polarization voltage or any voltage Since such a signal may cause a measurement error, only the polarization voltage or some voltage is corrected and only the output signal of the sensor is taken out. The polarization voltage correction circuit 25 will be described below.

The specific circuit configuration of the polarization voltage correction circuit 25 is shown in FIG. 3, and the sensor output signal output from the sensor portion 12 shown in FIG. 2 is from the output side of the high impedance conversion circuit 14 to the + side. It is input to the voltage level detector 26 and the − side voltage level detector 27. The output voltages from these voltage level detectors are respectively passed through the resistor R to the operational amplifier 28.
(For example, the gain is 1/2) It is configured to be input to the non-inverting input terminal. The output signal of the operational amplifier 28 is
It is configured to be fed back to the non-inverting input terminal of the operational amplifier 28 via the resistor R / 2 and input to the non-inverting input terminal of the operational amplifier 29 via the resistor R. The output signal of the high impedance conversion circuit 14 is input to the non-inverting input terminal of the operational amplifier 29 (for example, gain is 1) via the resistor R.

The polarization voltage correction circuit 25 thus configured operates as follows.

That is, the sensor output signal is now a rectangular wave output signal V
Then, the combined signal when the polarization voltage Vb is superimposed is
As shown in FIG.

That is, when the output signal of the + side voltage level detector 26 is P1, P1 = V + Vb, and when the output signal of the − side voltage level detector 26 is P2, P2 = −V + Vb. Therefore, the output A1 of the operational amplifier 28 is -1/2 (P1 + P2) = -1/2
(V + Vb-V + Vb) =-1/2 (2Vb) =-Vb.

Further, the output A2 of the operational amplifier 29 is − {(V
+ Vb) + (-Vb)} =-V, on the other hand, when the-side,
-{-(V + Vb) + (-Vb)} = V. as a result,
The output signal becomes a signal of only V, and the influence of the polarization voltage can be removed to extract only the sensor output signal.

Further, another embodiment of the present invention will be described with reference to FIG. The embodiment shown in FIG. 5 shows only a portion corresponding to the sensor portion shown in FIG. 1, and the overall structure is almost the same as that of the embodiment shown in FIG. 1 (here, Since the configuration other than the sensor portion is the same, illustration and description thereof will be omitted.) The difference from the embodiment shown in FIG. 1 is that the one shown in FIG. In contrast to what is displayed, in FIG. 5, the display of the liquid leakage point position is a block display.

That is, referring to FIG. 5, there is shown a sensor portion 12 similar to the sensor portion shown in the embodiment of FIG. 1, and this sensor portion 12 includes a signal line 12a, a resistance line 12b and a suction line.
It has 12c. The sensor portion 12 is divided into, for example, three blocks, that is, a block position A, a block position B, and a block position C, as shown in the figure, and a fixed resistor R is connected in series to the resistance wire 12b at each block position. Connected to a relationship.

At block position A and block position B, wicking line 12c
The sensor electrodes 2 and 4 in the bare wire state, which are connected to each other, are respectively arranged, and the sensor electrodes 1 and 3 in the bare wire state, which are connected to the resistance wire 12b in the next stage of each resistor R, are connected. Has been done.

At the block position C, the bare wire sensor electrode 6
The sensor electrode 5 in a bare wire state is connected to the resistance wire 12b at the next stage of the resistor R while being connected in series with the resistance wire 12c. Therefore, the block position A and the block position B
In, the sensor electrodes are arranged in a branched manner, and at the block position C, the sensor electrodes are connected in series and arranged. With this configuration, when liquid leakage occurs between the pair of sensor electrodes at each block position, the output that represents the ratio of the total resistance value at all block positions to the total resistance value up to the leak point By outputting a signal and performing the same signal processing as that of the embodiment shown in FIG. 1, the block position of the liquid leakage point can be detected and displayed. In the above-described embodiment, the sensor electrodes are branched and arranged at the block position A and the block position B, and the sensor electrodes are connected and connected in series at the block position C. It is also possible to form a terminal portion at C and further connect the block position A and the block position B as described above to this terminal portion.

Further, in the above-mentioned embodiment, the pair of bare wire sensor electrodes are arranged at each block position, but instead of the sensor electrodes, pressure, heat, light, gas, etc. are detected to perform the switching operation. Sensors with various switches (for example, pressure switch or thermal switch such as bimetal)
It is also possible to detect and display the abnormal position of pressure, temperature, light, gas, etc. by disposing.

In the above embodiment, the voltage applied from the power supply is described as a rectangular wave voltage, but the present invention is not limited to this, and it may be configured to apply a DC voltage. Although the case of the voltage ratio of outputting a voltage proportional to the distance of the leak point has been described, the present invention is not limited to the above embodiment, and a resistance ratio or the like may be used. Within the technical concept of
Of course, it can be changed.

(Effects of the Invention) As described above, according to the liquid leakage position detection device of the present invention, when the liquid leakage is detected, the sensor portion that outputs a signal proportional to the distance of the leakage point, and the clock signal. , An up / down counter to which the clock signal is input by a predetermined timing signal issued from a timing circuit, a digital / analog converter to which an output signal from the up / down counter is input, and the up / down counter. A display for displaying a count value counted by a down counter, an output signal from the digital / analog converter and an output signal of the sensor portion are input, and the up / down counter is compared by comparing these signals. Comparator for performing up-counting and down-counting of Since the digital-to-analog converter is configured to include a power supply that applies a constant rectangular wave signal, even if the length of the sensor line arranged to detect the liquid leakage position changes, It is possible to measure easily and easily with a constant accuracy without deteriorating the detection accuracy of the leak position, and always with a constant accuracy even if the resistance value of the sensor wire changes due to temperature etc. Can
Further, even if the conductivity of the liquid to be measured for measuring the leak is changed, there is a great effect that the liquid can always be measured with a constant accuracy.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an embodiment of the liquid leakage position detecting device according to the present invention, FIG. 2 is a schematic explanatory view of another embodiment of the liquid leakage position detecting device according to the present invention, and FIG. FIG. 4 is a circuit configuration diagram of a polarization voltage correction circuit used in the present invention, FIG. 4 is a diagram showing a combined signal when a polarization voltage is superimposed on a sensor output signal, and FIG. 5 is a liquid leakage position detection device according to the present invention. It is a schematic explanatory drawing of other Example using the block position of. 1, 2, 3, 4, 5, 6 ... Sensor electrode 10 ... Leakage position detection device, 11 ... Power supply 12 ... Sensor part, 13 ... Digital / analog converter 15 ... Up / down counter 16 ... Indicator, 17 ... Comparator 18 ... scale adjustment amplifier, 22 ... timing circuit, 23 ... oscillation circuit 25 ... polarization voltage correction circuit. A, B, C ... Block position

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuyuki Kojima 2-25-25 Miyasaka, Setagaya-ku, Tokyo Junko Co., Ltd. (72) Inventor Hiroyuki Sugibuchi 2-25-25 Miyasaka, Setagaya-ku, Tokyo Junkosha Co., Ltd. (72) Inventor Kimoto Shimada 5-1953 Kamisooka, Shiki City, Saitama Prefecture Examiner Hiroyuki Kikui, Spandonyx Co., Ltd.

Claims (5)

[Claims] 1. A sensor part for outputting a signal proportional to a distance of a leak point when a leak of liquid is detected, an oscillator circuit for generating a clock signal, and a clock signal generated by a timing circuit. An up / down counter to which is input, a digital / analog converter to which the output signal from the up / down counter is input, a display for displaying the count value counted by the up / down counter, and the digital / analog The output signal from the converter and the output signal of the sensor portion are input, and these signals are compared,
A liquid leakage position detection device comprising: a comparator that performs up-counting and down-counting of the up / down counter; and a power supply that applies a constant rectangular wave signal to the sensor portion and the digital-analog converter. 2. The liquid leakage position detecting device according to claim 1, wherein a scale adjusting amplifier is provided at a stage subsequent to the digital-analog converter. 3. The liquid leakage position detection device according to claim 1, wherein a polarization voltage correction circuit is provided in front of the comparator. 4. The liquid leakage position detecting device according to claim 1, wherein the sensor portion is divided into blocks, and the liquid leakage position is detected and displayed for each block. 5. A sensor portion which outputs a signal proportional to the distance of the position where the state change occurs, an oscillator circuit which generates a clock signal, and a predetermined timing signal which is issued from a timing circuit when a state change is detected. An up / down counter to which the clock signal is input, a digital / analog converter to which an output signal from the up / down counter is input, and a display for displaying a count value counted by the up / down counter, An output signal from the digital-analog converter and an output signal of the sensor portion are input, and a comparator for comparing these signals and performing up-counting and down-counting of the up-down counter, the sensor portion, and A constant square wave signal to the digital-analog converter A applied to the power supply, divide the sensor portion for each block, the pressure in each block,
A position detection device that has a sensor that detects heat, light, gas, etc., and that performs switching operation, and that detects and displays the position where the state change occurs.