JPH04110628A - Detecting apparatus for position of leaking liquid - Google Patents

Abstract

PURPOSE:To perform measurement with constant accuracy all the time by outputting a signal as the ratio of a signal which is applied on a distance to a leaking point when a sensor part has detected leaking liquid. CONSTITUTION:The counted value is outputted from an up/down counter 15 into a digital/analog converter 13. The clock signal oscillated in an oscillation circuit 23 is inputted into the up/down counter 15 through AND circuits 19 and 21 at the specified timing issued from a timing circuit 22. In a comparator 17, the output signal from the digital/analog converter 13 is compared with the output voltage of a sensor, and the signal is controlled. As a result, the clock signal which is inputted into the digital/analog converter 13 from the up/down counter 15 is controlled. When the state wherein the up/down counter 15 repeats the up and down operations is obtained, the measuring position of the liquid leaking position is judged. The output signal of the up/down counter 15 at this time is inputted into a display device, and the liquid leaking position is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a liquid leakage position detection device that detects the leakage position of liquid when it leaks from equipment for transporting or storing liquid.

(Prior Art) Conventionally, when transporting liquids such as hot water and chemicals through pipelines, accidents may occur in which liquids leak from the pipelines. Various liquid leakage position detection devices have been proposed so far. This type of liquid leakage position detection device has as its main components a detection part equipped with a power supply, a comparison resistor (reference resistor), etc., and a sensor part equipped with a sensor line, a signal line, etc. Some resistors and sensor wires are connected in series.

In the sensor part of this liquid leakage position detection device, the position is detected by measuring the sensor wire resistance value from the starting point of the sensor wire to the liquid leakage point as an absolute value, in other words, as an absolute value of the voltage drop. If the length of the sensor wire has to be changed depending on the installation and deployment of the leakage position detection device (if it is necessary to change the length, the length of the sensor wire must be changed from the same length that was previously used for the detection part to detect the leakage position). With the comparison resistor, the accuracy of detecting the leakage position is relatively inferior, and in order to maintain the detection accuracy, it is necessary to change the comparison resistor. There is the annoying problem of having to change the container.

Furthermore, as long as measurements are made using this comparison resistor, the resistance value of the sensor wire used for position detection will always be constant to prevent variations in manufacturing, etc., in order to prevent errors in position detection. Must be maintained at a value.

In addition, the resistance value of the sensor wire used for position detection must always be maintained at a constant value, and this also applies to temperature, so materials with very small resistance changes due to temperature etc. are selected. There is also the problem that there are restrictions due to the material of the sensor wire used.

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

Furthermore, in the case of constant current circuits, the power supply output varies greatly depending on the conductivity of the liquid to be measured, and especially in the case of liquids with low conductivity, the resistance at the leak point of the liquid increases, and the power supply capacity is large. Something is needed.

On the other hand, a so-called Murray loop (Murray 1loop) type liquid leak position detection device using a Wheatstone bridge, that is, a liquid leak position detection device that detects the position by measuring the proportional ratio between the total length of the sensor part and the leak point. In the detection device, since the leakage part resistance to be measured at the leakage point is larger than the sensor wire resistance value, the measurement voltage applied to the bridge is considerably smaller than the power supply voltage, and the accuracy is poor (
Become. This tendency is particularly noticeable for liquids to be measured whose electrical conductivity is low.

(Problems to be Solved by the Invention) The present invention has been made in view of the above points, and its first purpose is to improve the unit length of the sensor wire arranged to detect the position of liquid leakage. To provide a liquid leakage position detection device that can simply and easily measure the leakage position with constant accuracy without deteriorating the detection accuracy of the leakage position even if the resistance value of the contact or the total resistance value changes. It is.

A second object of the present invention is to provide a leakage position detection device that can always measure with constant accuracy even if the resistance value of the sensor wire varies due to manufacturing etc. or changes due to temperature etc. It is to provide.

A third object of the present invention is to provide a liquid leak position detection device that can always measure with constant accuracy even if the conductivity of the liquid to be measured changes.

A fourth object of the present invention is that even if a signal such as an undesirable voltage is superimposed on the sensor wire used to measure the leakage position, this signal can be canceled and the leakage can be performed without measurement error. An object of the present invention is to provide a liquid position sensing device.

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

(Means for Solving the Problems) The above object is achieved by the leakage position detection device of the present invention. That is, to summarize, the present invention includes: a sensor portion that outputs a signal proportional to the distance to the leak point when a liquid leak is detected; an oscillation circuit that generates a clock signal;
an up/down counter to which the clock signal is input based on a predetermined timing signal generated from a timing circuit; a digital/analog converter to which the output signal from the up/down counter is input; and a count counted by the up/down counter. A display device that displays numerical values, an output signal from the digital-to-analog converter, and an output signal from the sensor section are input, and these signals are compared to calculate up and down counts of the up/down counter. This liquid leakage position detection device includes a comparator that performs the detection, and a power source that applies a constant rectangular wave signal to the sensor portion and the digital-to-analog converter.

(Function) According to the liquid leakage position detection device of the present invention, the sensor portion
When a leaked liquid is detected, the sensor is configured to output a signal as the ratio of the signal applied to the distance to the leak point to the signal applied to the entire length of the sensor.
Even if the length of the sensor wire installed to detect the position of a liquid leak changes, the detection accuracy of the leak position will not deteriorate, and the measurement can be easily and easily always performed with a constant accuracy. In addition, even if the resistance value of the sensor wire changes due to temperature, etc., measurements can always be made with a constant accuracy.Furthermore, even if the conductivity of the liquid to be measured for leakage changes,
Measurements can always be made with constant accuracy.

(Examples) Hereinafter, the present invention will be described based on examples thereof with reference to the accompanying drawings.

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

Referring to FIG. 1, a liquid leakage position detection device 10 of the present invention is shown, and this liquid leakage position detection device 10 has a power supply 11
and a sensor part 1 connected in parallel with this power supply 11
It has 2. Here, the power supply 11 has a frequency of 0, for example.
．． It is a power supply that applies a 5Hz rectangular wave voltage to the sensor part 12, and the sensor part 12 has a signal line 12a1 and a resistance line 12b.
and a suction line 12c, and this sensor portion 12
is configured to generate an output voltage proportional to the voltage applied from the power supply 11 according to the position of the leakage point when leaking liquid is detected (in this embodiment, the output voltage is proportional to the voltage applied from the power supply 11). output voltage proportional to the length of the resistance wire). That is, when the sensor portion 12 detects leaked liquid, a signal is generated as a ratio of the voltage applied to the length of the resistance wire (distance to the leak point) to the voltage applied to the entire length of the sensor. Since it outputs a voltage proportional to the distance of the leak point.

One end of the sensor portion 12 is connected to a reference voltage terminal of a digital-to-analog converter 13 of an external reference voltage application type, and the other end is grounded. If liquid leakage occurs in the sensor portion 12, the sensor portion 12
The above-mentioned sensor output voltage is generated from the sensor output voltage, and this sensor output voltage is input to the high impedance conversion circuit 14.

Reference number 15 is an up/down counter, and this up/down counter 15 outputs a digital signal to the digital-to-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 a comparator 17, and the output signal from the digital-to-analog converter 13 is input to the inverting input terminal of the comparator 17. This comparator 17 compares the sensor output value inputted via the high impedance conversion circuit 14 and the output value of the digital-to-analog converter 13.

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

The other end inputs of the AND circuits 19 and 21 are configured to receive a clock signal generated from an oscillation circuit 23 via a timing circuit 22. The output signals of these AND circuits 19 and 21 are configured to be input to the up counting side and down counting side of the up/down counter 15, respectively. Note that when the timing circuit 22 inputs the clock signal emitted from the oscillation circuit 23 to the other end input of the AND circuits 19 and 21, the timing circuit 22 inputs the clock signal from the AND circuits 19 and 21 in accordance with the timing of the applied voltage from the power supply 11. A timing signal is generated so as to apply a clock signal to the input on the other end side.

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

Now, when the liquid leakage position detection device of the present invention having the above-described configuration is in an operating state, that is, the rectangular wave voltage from the power supply 11 is applied to the sensor section 12, and the reference voltage of the digital-to-analog converter 13 is applied. When a liquid leaks from the sensor part 12 when the voltage is applied to the terminal, an output signal corresponding to the position of the liquid leak, that is, an output voltage proportional to the distance of the leak point, is generated through the suction line 12c of the sensor part 12. is input from the sensor section 12 via the high impedance conversion circuit 14 to the non-inverting input terminal of the comparator 17, while the output voltage from the digital-to-analog converter 13 is input to the inverting input terminal of the comparator 17.

The output voltage from the digital-to-analog converter 13 is set to be a predetermined voltage value according to the count output from the up/down counter 15.

Here, the digital signal is input from the up/down counter 15.
The count value output to the analog converter 13 is determined by converting the clock signal generated from the oscillation circuit 23 into the timing circuit 2.
2 is input to the up/down counter 15 via AND circuits 19 and 21 at a predetermined timing. In this embodiment, a clock signal is input to the up-fist-down counter 15 using the pulse width on the plus side of the rectangular wave voltage generated from the power supply 11 as timing. These output signals are then compared by a comparator 17.

At this time, if the sensor output voltage from the sensor section 12 that is input to the comparator 17 via the high impedance conversion circuit 14 is larger than the output signal of the digital φ analog converter 13, the output signal of the comparator 17 will oscillate. It is inputted together with the clock signal from the circuit 23 to the up side of the up/down counter 15 via the AND circuit 19, and as a result operates to increase the set value of the digital/analog converter 13.

In this way, the analog signal output from the digital-to-analog converter 13 increases, and the comparator 17
When the voltage becomes larger than the sensor output voltage input to
As a result, the set value of the digital-to-analog converter 13 is reduced.

In this way, the comparator 17 compares and controls the output signal from the digital-to-analog converter 13 with respect to the sensor output voltage, and as a result, the clock signal input from the up/down counter 15 to the digital-to-analog converter 13 is When the up/down counter 15 alternately repeats up and down operations, it is determined that the leakage position has been measured, and the output signal of the up/down counter 15 at this time is displayed on the display 16. is entered and the leak location is displayed. In addition, the power supply 1 mentioned above
The reason why the applied voltage in Example 1 is a 0.5 Hz rectangular wave voltage is 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 in the embodiment shown in FIG. 1 will be given the same reference numerals, and their explanation will be omitted.

The embodiment shown in FIG. 2 is almost the same as the embodiment shown in FIG. 1, but differs from the embodiment shown in FIG.
A scale adjustment amplifier 18 and a high impedance conversion circuit 14 are provided at the next stage of the digital-to-analog converter 13.
The difference is that a polarization voltage correction circuit 25 is added at the next stage.

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

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

The sensor applied voltage applied from the power supply 11 to the sensor part 12 is E1 The sensor output voltage is V1 The sensor output coefficient is x (
0 to 1), the sensor output voltage V=Ex. On the other hand, the applied voltage applied to the digital-to-analog converter 13 is also E, similar to the sensor part, and the digital
Assuming that the output value of the analog converter 13 is y1, the output coefficient of the digital-to-analog converter 13 is x (0 to 1), and the scale adjustment coefficient is 2, the output value of the digital-to-analog converter 13 is y=Exz. Here, X is a sensor output coefficient or an output coefficient of the digital-to-analog converter 13, which is operated to have the same value depending on the circuit. Therefore, the relationship y=Vz holds true. As a result, the output value of the digital-to-analog converter 13 is the sensor output voltage multiplied by the scale adjustment coefficient. Therefore, by adjusting the scale adjustment coefficient Z, scale adjustment can be performed.

Next, the polarization voltage correction circuit 25 corrects the polarization voltage when the sensor output signal is superimposed with a signal such as a polarization voltage generated when detecting a liquid leakage or some other undesirable voltage.
Since this polarization voltage or a signal such as some voltage may cause a measurement error, the polarization voltage correction circuit 25 is designed to correct only the polarization voltage or some voltage and extract only the output signal of the sensor. This is explained 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 section 12 shown in FIG.
4 is input to the + side voltage level detector 26 and the one side voltage level detector 27. The output voltages from these voltage level detectors are configured to be input to a non-inverting input terminal of an operational amplifier 28 (eg, gain 1/2) via a resistor R, respectively. operational amplifier 2
The output signal of 8 is passed through the resistor R/2 to the operational amplifier 28.
The signal is fed back to the non-inverting input terminal of the operational amplifier 29, and is also input to the non-inverting input terminal of the operational amplifier 29 via the resistor R. Also, this operational amplifier 29
The output signal of the high impedance conversion circuit 14 is inputted via a resistor R to a non-inverting input terminal (for example, a gain of 1).

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

In other words, the sensor output signal is now converted into a rectangular wave output signal V
Then, the composite signal when the polarization voltage vb is superimposed is as shown in FIG.

That is, the output signal of the + side voltage level detector 26 is
P1=v+vb, and if the output signal of the -control voltage level detector 26 is P2, then P2=-V+Vb. Therefore, the output A1 of the operational amplifier 28 is -1
/2 (P1+P2)=-1/2 (V+Vb-V+V
b)=-1/2 (2vb)=-vb.

Furthermore, when the output A2 of the operational amplifier 29 is on the + side, -(
(V+Vb)+ (-Vb)) =-V, and on the other hand,
When on the − side, −(−(V+Vb)+(−vb))=v. As a result, the output signal becomes only a signal of (1), and the influence of the polarization voltage can be removed and only the sensor output signal can be extracted.

Further, another embodiment of the present invention will be described with reference to FIG. The embodiment shown in FIG. 5 shows only the part corresponding to the sensor part shown in FIG. 1, and its overall configuration is almost the same as the embodiment shown in FIG. 1 (here,
Since the configuration other than the sensor part is the same, illustration and explanation thereof will be omitted. In contrast, in the one shown in FIG. 5, the position of the leakage point is displayed in a block-like manner.

That is, referring to FIG. 5, there is shown a sensor portion 12 similar to the sensor portion shown in the embodiment of FIG.
This sensor part 12 includes a signal line 12 a s resistance line 12
b and a wicking line 12c. For example, as shown in the figure, the sensor portion 12 is divided into three blocks: block position A, block position B, and block position C, and a fixed resistor R is connected in series to the resistance wire 12b at each block position. It is connected to the.

At block position A and block position B, suction line 12
A sensor electrode 2.4 in a bare wire state is connected to the resistor R, and a sensor electrode 1.3 in a bare wire state is connected to the resistance wire 12b at the next stage of each resistor R.
is connected.

At the block position C, the sensor electrode 6 in a bare wire state is connected in series to the suction wire 12c, and the sensor electrode 5 in a bare wire state is connected to the resistance wire 12b at the next stage of the resistor R. Therefore, at block position A and block position B, the sensor electrodes are arranged in a branched manner, and at block position C.
In this example, sensor electrodes are connected in series.

With this configuration, when liquid leakage occurs between paired sensor electrodes at each block position, an output representing the ratio of the total resistance value up to the liquid leakage point to the total resistance value at all block positions is generated. By outputting a signal and performing signal processing similar to the embodiment shown in FIG. 1, the block position of the leak point can be detected and displayed. In addition, in the above embodiment, at block position A and block position B,
The sensor electrodes are branched and arranged, and the sensor electrodes are connected in series at block position C, but a terminal part is formed at this block position C, and this terminal part is connected as described above. It is also possible to adopt a configuration in which block position A and block position B are further connected.

In addition, in the above embodiment, a pair of bare wire sensor electrodes is arranged at each block position, but instead of this sensor electrode, a switching operation is performed by sensing pressure, heat, light, gas, etc. Sensors with various switches (e.g. pressure switches or thermal switches such as bimetallic ones)
It is also possible to detect and display the location of abnormalities such as pressure, temperature, light, gas, etc. by installing a sensor.

In the above embodiments, the voltage applied from the power supply is described as a rectangular wave voltage, but the present invention is not limited to this, and can also be configured to apply a DC voltage. Although the case of the voltage ratio in which a voltage proportional to the distance of the leakage point is output has been described, the present invention is not limited to the above embodiments, and a resistance ratio etc. may be used, and that aspect is similar to the present invention. It goes without saying that various modifications and changes can be made within the technical concept.

(Effects of the Invention) As described above, the liquid leak position detection device of the present invention includes a sensor portion that outputs a signal proportional to the distance to the leak point when a liquid leak is detected, and a clock signal. an oscillation circuit that generates an oscillation circuit, an up/down counter to which the clock signal is input based on a predetermined timing signal generated from a timing circuit, a digital-to-analog converter to which an output signal from the up/down counter is input; The output signal from the digital-to-analog converter and the output signal from the sensor section are inputted to a display that displays the counted value counted by the down counter, and these signals are compared and the output signal is input to the up/down counter. The device is configured to include a comparator that performs up counting and down counting, and a power source that applies a constant rectangular wave signal to the sensor portion and the digital-to-analog converter, so that the position of liquid leakage can be detected. Even if the length of the sensor wire installed for the purpose of the sensor changes, the detection accuracy of the leakage position will not deteriorate, and the sensor wire can be easily and easily measured with constant accuracy. Even if the resistance value changes, it can always be measured with constant accuracy.
Furthermore, even if the conductivity of the liquid to be measured for leakage changes, it has the great effect of always being able to measure with constant accuracy.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of one embodiment of the liquid leak position detection device according to the present invention, FIG. 2 is a schematic explanatory diagram of another embodiment of the liquid leak position detection device according to the present invention, and FIG. A circuit configuration diagram of a polarization voltage correction circuit used in the present invention. FIG. 4 is a diagram showing a composite signal when a polarization voltage is superimposed on a sensor output signal. FIG. 5 is a diagram showing a liquid leakage position detection device according to the present invention. FIG. 3 is a schematic explanatory diagram of another embodiment using block positions of FIG. 1.2.3.4.5.6...Sensor electrode 10...Leakage position detection device, 11...Power source 12...Sensor part, 13...Digital-to-analog converter 15...
Up/down counter 16...Display device, 17...Comparator 18.
... Scale adjustment amplifier, 22 ... Timing circuit, 23 ... Oscillation circuit 2
5...Polarization voltage correction circuit. A, B, C...Block position patent applicant Jun Ko Co., Ltd. Company quality 3 times 2 degrees + eyes

Claims (1)

[Claims] 1) A sensor section that outputs a signal proportional to the distance to the leak point when a liquid leak is detected, an oscillation circuit that generates a clock signal, and a predetermined timing signal that is generated from a timing circuit. an up/down counter to which the clock signal is input; a digital-to-analog converter to which the output signal from the up/down counter is input; and a display for displaying the count counted by the up/down counter; the sensor section and A leakage position detection device comprising: a power source that applies a constant rectangular wave signal to the digital-to-analog converter; 2) The liquid leakage position detection device according to claim 1, wherein a scale adjustment amplifier is provided at the next stage of the digital-to-analog converter. 3) The liquid leakage position detection device according to claim 1 or 2, wherein a polarization voltage correction circuit is provided before the comparator. 4) The liquid leak position detection device according to any one of claims 1 to 4, wherein the sensor portion is divided into blocks, and the liquid leak position is detected and displayed for each block. 5) A position detection device that divides the sensor portion into blocks and has a sensor for each block that senses pressure, heat, light, gas, etc. and performs a switching operation, and detects and displays the position where a state change occurs.