JPS6140514A - Apparatus for measuring amount of liquid - Google Patents

Abstract

PURPOSE:To make it possible to detect the change in the level of the liquid in a tank oer a wide range, by constituting a liquid depth measuring electrode from a double pipe while forming a comparing electrode to be always immersed in a liquid from a multiple pipe. CONSTITUTION:The negative electrode of a liquid depth measuring electrode MP, that is, the outer pipe 20 is electrically connected to the negative electrode 13 of a comparing electrode CP at the lower end thereof by a conductive support member 22 and the upper end thereof is supported by a conductive support member 23. A positive electrode, that is, an inner pipe 21 is supported at the lower end thereof by a support member 15 and the upper end thereof is supported by a support member 24 made of an insulating material. An opening not shown in the drawing is provided to the support member 15 by drilling and allows the gap parts between multiple pipes constituting the comparing electrode CP to communicate with the gap between the inner and outer pipes 20, 21 of the liquid depth measuring electrode MP and, by this structure, fuel oil F is penetrated between the inner and outer pipes 20, 21 from below. By this constitution, the liquid depth measuring electrode can be made long and the comparing electrode can be made short and the above-mentioned object can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid amount measuring device, and particularly for measuring the amount of liquid, such as fuel oil, contained in a tank. This relates to a capacitive liquid level measuring device.

If two metal plates constituting a positive electrode and a negative electrode are placed facing each other in a container, and a liquid such as Ganrin is introduced into the container, the capacitance value between the two electrodes will change depending on the height of the liquid level. is well known. This is due to the fact that the dielectric constant of air, which is the part not immersed in the liquid, is approximately 1.0, whereas the dielectric constant of gasoline is approximately 2.1. In other words, the capacitance value increases as the height of the liquid level increases.

A liquid level measuring device that uses the above principle, that is, a measuring electrode with a positive electrode and a negative electrode is placed inside the tank, measures the capacitance value between the two electrodes, calculates the liquid level height from this, and also takes tank dimensions into consideration. Devices that measure liquid volume by being placed in a container have been proposed in the past, but this type of capacitance type liquid volume measuring device has not yet been put into practical use. This seems to be due to the following reasons. In other words, the dielectric constant of the liquid changes depending on the temperature, so it is effective for cases where there is almost no temperature change, such as liquid in a constant temperature tank, but it is effective for liquids in general outdoor tanks and gas stations. This is because when there is a temperature change, such as in fuel oil in an underground tank, highly accurate measurements cannot be made unless the change in dielectric constant is corrected accordingly. In addition, the static 7 of liquid depth measurement jγ, which changes depending on the type of liquid and liquid temperature in this tank,
1! This is because the adjustment of Mli for the capacity Δ1 must also be carried out in response to changes in the liquid type and temperature in the tank so that the conditions are the same.

Therefore, two objects of the present invention are to provide, in addition to the liquid if measuring electrode, a comparison electrode which is constantly immersed in the liquid and which determines the change in reading rate depending on the temperature change of the liquid;

The area of the electrode plate of the comparison electrode is determined so that the capacitance of the comparison electrode (a'i or liquid depth ff1ll) is approximately equal to the capacitance value determined by ff1l+ by the constant electrode, and It is an object of the present invention to provide a liquid level measuring device with a high accuracy of 1-degree so that capacitance changes of dependent liquid source measuring electrodes can be appropriately corrected and measurements can be made accurately.

The invention will now be explained in more detail with reference to an embodiment shown in the accompanying drawings.

FIG. 1 schematically shows a liquid level measuring device according to the invention, which is applied to measuring the level of liquid, especially gasoline, contained in a tank buried underground. Although only one lower tank R5 containing fuel oil F is shown in this figure, a plurality of tanks may actually be installed.

A detector DT belongs to each underground tank R5. This detector DT will be described in detail in connection with Figures 2 and 3 below, and is configured as a capacitance measuring rod, inserted in an upright position in an underground tank R8, and has a water detection pole. Including 1y' A comparative electrode CP which is immersed in a Br solution, and a liquid that is on one side of the comparative electrode and measures the capacitance value according to the curved surface level. It has a built-in measuring electrode MP and a reference electrode, and converts the capacitance values measured by the comparison electrode and the liquid source measuring electrode and the capacitance values measured by the built-in reference electrode into frequencies. A level transmitter that sends these as output 1. It is equipped with F. The output from the level transmitter 1゜P dedicated to each underground tack R5 is a signal sent to a control box C8 installed in an office or the like.
Input via %lA. Conte.

The roll box CB is common to each tank.

Numerical display 811 that displays tank number, liquid volume, etc.

An upper limit notification of the amount of lIk in the tank for each tank -/7zo 2, a lower limit notification lamp 3, and a tank water M notification lamp 4,
Tank selection button 5, splitter 6 and its operation button 7, L
A notification buzzer 8 that provides audible information when the reporting wraps 2, 3, and 4 are activated, and a key 9 for data input installed inside the lower cover of the l-box cn. is set up. Further, an alarm device 10 installed at a desired location is connected to a control box CB by a signal line 11, and an operation button 7' of the alarm device 10 is provided on the control box CB.

FIG. 2 shows in detail the structure of the detector DT section shown schematically in FIG. A detector DT is placed at the bottom of the underground tank RS to prevent the fuel oil F from entering the tank, or water that has been separated from the fuel oil or has entered the tank for some reason. A cannula J2 made of an electrically insulating material and having a frontage 121 that allows this is disposed. On one side of the cannula 12 is a metal concentric multiple vibrator 13.1.
3', 13", 14. 14', 14", with the outermost pipe as the negative electrode, alternately positive electrode - negative electrode - positive electrode.
..., the positive electrodes 14, 14', +4'' are supported by the support member 5 made of insulating material, and the conductive member 16 is
A comparison electrode CP is also arranged, which is connected to the electrode 13, and whose negative electrodes 13, 13' and +317 are supported by a support member 17 made of a conductive material. The concentric multiple pipes constituting the comparison pole CP communicate with the inside of the mantle 12 through an opening (not shown) bored in the support member 17, and are constantly filled with fuel oil F. It has been made into a state, and it is also a comparative pole CP
It is preferable that the water sensing electrode 19 is built in at the bottom thereof. One side of the comparison electrode CP is composed of a double metal vibrator, with the outer pipe 20 serving as the negative electrode and the inner vibrator 21 serving as the negative electrode.
A liquid source measuring electrode FilP is arranged between the two pipes, with F as a positive electrode and fuel oil F enters through the comparison electrode cP. The negative electrode of this constant pole MP, that is, the lower end of the outer pipe 20 is connected to the comparative electrode C by a conductive support member 22.
It is electrically connected to the negative electrode 13 of P, and its upper end is supported by a conductive support member 23. On the other hand, the lower end of the positive electrode, that is, the inner pipe 21 is connected to the support member 15 (this part has an opening (not shown) in the gap between the multiple pipes constituting the comparison electrode CP and the inside and outside of the liquid iW measurement electrode 1 + IP. pipe 20
．． 21, so that the fuel 7Il+F can enter from below between the inner and outer pipes 20 and 21), and the upper end is supported by a support member made of an insulating material. 24. Inside the inner pipe 21 is a W connected to the positive electrode of the comparison electrode CP.
1 25 is arranged to transmit capacitance information measured at the comparison electrode CP including the water sensing electrode 19. Near the upper end of the outer pipe 20, there is a
are perforated so that the fuel oil can easily enter between the inner and outer pipes 20,21. Above the liquid 1 volume measuring pole M+', a level transmitter 1. F, a joint pipe 29 connected above the vibrator 26 via the JB electric support member 27,
While maintaining the joint pipe in a vertical state, a comparison electrode CP including a water detection electrode 19, a liquid source measurement electrode MI' and a level transmitter 1. A head box 30 is provided for convenient maintenance of F. The above cannula 1
2 and the outermost pipe of the comparison pole CP to pole 13. The outermost pipe 13 and the outer pipe 20 of the liquid source measurement pole MP. The outer pipe 20 and the metal pipe 2 containing the level transmitter LP
6. The metal pipe 26 and the joint pipe 29 are connected by an appropriate fixing means such as a screw. Therefore, by explaining the fixing member, the detector OT can be disassembled and one part can be easily replaced. being done. A mesh member 31 is provided in a portion of the sleeve 12 to prevent dust, etc., which may be suspended in the liquid in the tube, from reaching the comparison electrode or the liquid source measurement electrode. It is done like this. The comparison electrode CP is configured as a concentric multiple pipe by increasing the electrode plate area without increasing its height or length N method, and the capacitance value determined by 1ffll+ by the liquid 1st measurement electrode. This is to make it possible to accurately measure changes in capacitance depending on the liquid type and temperature by making the values almost the same. Level transmitter LF is a signal! The capacitance value measured at the comparison electrode cP, which is connected to the pipe 26 which is the negative electrode by 32 and includes the water detection electrode 19 sent from the signal line 25, and the measurement electrode 111r' sent from the signal line 33.
The capacitance values measured at the reference poles are converted into frequencies, and the capacitance values measured at the reference poles, which have their own standards, are converted into frequencies, and these frequencies are controlled via the signal line 34. The output is transmitted to the box C11 (see FIG. 1), and is equipped with various elements as will be described later in connection with FIG. The substrate 37 was mounted on a substrate 37 supported by the metal pipe 26, and the substrate 37 was placed inside the metal pipe 26.
Second, it is embedded in an insulating synthetic resin, for example, an epoxy resin 38. 1. The joint vibrator 28 serves as a so-called mounting pipe provided for convenience 11 in order to install the comparison electrode (including the water detection electrode), the liquid source measurement electrode, and the level transmitter, which are the measurement parts. That is, each underground tank R9 has a different burial depth and a different diameter size, - the comparison electrode including the power water detection electrode must be placed near the bottom of the tank due to its nature, and the liquid source measurement electrode is located inside the tank. In addition, the level transmitter converts the capacitance value, which is analog information, into frequency, which is digital information, and since the capacitance value changes depending on temperature changes, it must be located close to the measurement pole. must be placed. For this purpose, a joint pipe 29 is provided, and the joint pipe is set in a relatively long shape, and can be cut during construction depending on the depth of burial of the tank and the diameter of the tank.

Figure 3 shows level transmitter 1. It is a block diagram of F, and 2
relays (contact relays) REI, RE2, 1.
C oscillation circuit O9C and reference pole (reference capacitor) EC
It is composed of. The reference capacitor that constitutes the reference electrode RC is a high-grade lI/denza whose capacitance value does not change much due to temperature changes or aging, and its capacitance value is the value measured by the comparison electrode and the liquid source measurement electrode. Those that are approximately the same are selected. In this level transmitter, the line 33 is connected to the positive electrode of the measuring electrode MP, that is, the inner pipe 21, the line 25 is connected to the positive electrode of the comparison 14c11, and the line 32 is connected to the common electrode of the 71111 constant electrode and the comparison electrode. It is connected to the negative pole, that is, the negative pole. 1. C oscillation circuit O
6C is equipped with a capacitor and a capacitor, and has the function of oscillating into a frequency signal based on the capacitance signal sent from the liquid source measurement electrode, comparison electrode, and reference capacitor RCh). Note that lines a and l) of the level transmitters 1 and C are relay lines, f is a transmission line for the measured frequency signal, and line g is a ground line.

Figure 4 shows the control box C11 shown in Figure 1.
FIG. 4 is a Bucock diagram showing the portion in slightly more detail in connection with the case where a plurality of tanks (five in the case of FIG. 4) are provided. In this figure, TDSC is a switching circuit, and lines 5 to 5 are signal lines from the level transmitter of the No. 1 tank to the level transmitter of the No. 5 tank, and are switched by the signal from the control circuit CPU. The circuit TDSC is configured to be switched sequentially. The signal from the switching circuit is sent to the & circuit MEC via the receiving circuit RFC. The memory circuit NEC stores 1. based on the capacitance values measured at the reference electrode, comparison electrode, and liquid source measurement electrode. The A1 formula that calculates the liquid depth from the frequency converted by the C oscillation circuit and the liquid volume from the liquid depth, the ``1 limit and lower limit liquid volume value of each tank, etc. are stored, and the values for each tank are stored. It has a liquid volume storage area. The arithmetic circuit OPC calculates the liquid volume based on the signal from the receiving circuit RFC and the monthly formula signal recorded in the memory circuit MEC, and calculates the liquid volume or the upper or lower limit liquid stored in the memory circuit MEC. It is also determined whether or not it corresponds to a quantity value. The signal from this arithmetic circuit 011C is then sent to a display-printer circuit (It)C+I'TC). The circuit (IDC+PTC) includes a notification buzzer 8, notification lamps 2, 3, 4 . It is connected to the display rod 1 and the printer 6. Tank selection button5. Printer operation button7. Timer T
M, manual key 9. The alarm button 7', the alarm circuit line and each of the circuits described above are connected to the control circuit CI)IJ.

Next, the device of the present invention will be explained in relation to its operation.

Depending on the signal from the control circuit CPLI, the switching circuit TDSC or the level transmitter of the No. 1 tank 1. When connected to the signal line ^1 from P, first the relay RE of the level transmitter is connected.
D. A signal is sent to RE2 and these relays are switched from reference pole (reference capacitor) RC to 1. C oscillator OS
A frequency signal responsive to the capacitance value measured by the reference electrode is connected to the memory circuit ME via the receiving circuit RFC.
The Fl described in C is carried out. Next, the signal to relay RF, 2 is l
v1 missing, comparison 4JiCP force Rano signal line 25 1. cQ
A frequency signal connected to the s-device O9C and responsive to the capacitance value measured by the comparison pole CP is stored in the storage circuit MEC via the reception circuit RFC. After Ji, the signal to relay RE+ disappears, and the signal line 33 or 1 from the liquid source measurement pole MP
．． A frequency signal receiving circuit R connected to the C oscillator OSC and responsive to the electrostatic field rit value measured by the measuring pole MP.
The data is stored in the memory circuit MFC via the FC. Memory circuit 1
．． These frequency signals recorded in the IEC are calculated using the liquid volume calculation formula already stored in the memory circuit.
1) The calculated liquid fL is converted to a liquid volume at C, and this calculated liquid fL is compared with the 1st limit and lower limit liquid volume values of the tank written in the same number memory circuit tα. lights up and buzzer 8 emits an alarm sound.

If it is below the lower limit value, the notification lamp 3 is lit and the buzzer 8 emits an alarm sound.

The time required to measure the liquid volume per tank is approximately 1 second.
If the measurement of the liquid in the first tank is not completed, the switching circuit DSC will be switched and connected to the signal ^2 from the second tank by the signal from the control circuit CP[I, and the liquid level in the second tank will be the same as above. It is measured in the same way. This liquid amount measurement operation is repeated up to the final tank, for example, the fifth tank, and the liquid amount from the first tank is measured again. In other words, the liquid in each tank
111 constant is always performed as a link.

Here, the liquid level of the tank designated by pressing the tank designation button 5 is displayed on the display it 1 together with the designated specific tank number, and if the tank designation button 5 is reset, the liquid level of the tank designated is displayed on the display meter 1. The time signal from the timer TM is displayed on the display M11.In other words, when the time signal from the timer TM is not displayed, the display M11 serves as the digital time signal 11.

If the tank designation button 5 is pressed in 4J ff3 and the fill/removal button 7 is pressed, the printer 6 prints out the time and the amount of liquid in the designated tank.

Further, if the alarm 7' is pressed at the end of the supply service of the liquid in the tank, for example when the gas station is closed, the liquid in each tank at that time will be stored in the memory circuit MEC.

For example, if water enters the tank for some reason, or if the liquid level changes by more than a certain amount due to theft, an alarm signal will be issued from the alarm circuit ^R, and this will be sent to the desired location, e.g. It is designed to activate the alarm IO installed at the security company. This liquid amount change signal can also be used to start the printer 6 via the control circuit CPυ and the printer circuit PTC to print out the time and change 1fft.

Furthermore, when water is stored up to the water detection electrode 19, the dielectric constant of water is approximately 1.
．． 6, the capacitance value increases rapidly and the oscillation frequency becomes abnormal when the comparison pole is connected to the LC oscillator. Moreover, a buzzer 8 is arranged to give an audible notification. Draining the water in the tank is done by the usual method, but 2
In a tank in which the device of the present invention is installed, the water surface height is usually at the level of the water detection electrode, and therefore the amount of water can be estimated, making it relatively easy to drain the water.

As described in detail above, in the liquid level measuring device of the present invention, the liquid source measurement electrode is made of a double tube, and the comparison electrode is made of a multi-tube, which is constantly immersed in the liquid. The electrode plate area is increased without increasing the length, and the capacitance value measured by the liquid source measurement electrode is approximately equal to that measured by the liquid source measurement electrode, so the liquid source measurement electrode can be made relatively long. The comparison electrode can be made short and can detect changes in the liquid level in a tank over a wide range, while also responding to changes in the dielectric constant of the liquid to be measured due to disturbances such as liquid type or temperature changes. This has the effect of correcting the value measured by the Ajt depth measuring pole, thereby making it possible to always accurately measure the liquid amount.

[Brief explanation of the drawing]

FIG. 1 of the accompanying drawings schematically shows a liquid level measuring device according to the present invention, which is applied to measuring the level of liquid, especially fuel oil, in an underground tank.
Figure 2 is a longitudinal cross-sectional view showing details of the detector section;
The figure is a block diagram showing a level transmitter, and FIG. 4 is a block diagram schematically showing a control circuit and related auxiliary circuits. Liquid source measurement electrode...MP, positive electrode (inner vibe)...
...21, Negative electrode (outer vibe) ...20.
Liquid to be measured...F, Comparison electrode...CP,
Reference pole...RC, LC oscillator...LP
, Display J1...1

Claims (1)

[Claims] A liquid depth measuring electrode has a positive electrode and a negative electrode, and the liquid to be measured can freely flow in and out between these electrodes, and the liquid depth measuring electrode is placed below the liquid source measuring electrode and is constantly immersed in the liquid. A comparison electrode for dielectric constant measurement, a level transmitter that converts the capacitance value measured by the liquid source measurement electrode and comparison electrode into a frequency, and a liquid volume calculated based on the frequency signal from the level transmitter. What is claimed is: 1. A liquid level measuring device equipped with a display meter for displaying , characterized in that the liquid source measuring electrode is a double tube, and the comparison electrode is a multiple tube.