Liquid level detection system

Abstract

To provide a liquid level detection system for detecting the liquid level in a container, in which the liquid level in the container such as a water storage tank can be more widely detected compared to conventional techniques and can be applied to multiple containers.SOLUTION: A liquid level detection system for detecting the liquid level in a container comprises a vent pipe, gas supply means, pressure measurement means, and a solenoid valve.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid level detection system for detecting the liquid level of a liquid in a container.

Background Art

[0002] In a self-circulating water purification device, a water level sensor is installed to prevent water from overflowing from a water storage tank. As a water level sensor installed in a self-circulating water purification device, for example, Patent Document 1 discloses a water level sensor including two types of electrodes and a control unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the water level sensor described in Patent Document 1, the liquid level in the water storage tank can be detected in a self-circulating water purification device. However, in the water level sensor described in Patent Document 1, since the two types of electrodes are attached so as to be suspended from the upper wall surface in the water storage tank, there is a problem that the detectable liquid level is limited to the height of the two types of electrodes. Further, the water level sensor described in Patent Document 1 has to be prepared for each water storage tank, and there is a problem that one water level sensor cannot be used for a plurality of water storage tanks.

[0005] Therefore, an object of the present invention is to provide a liquid level detection system for detecting the liquid level of a liquid in a container, which can detect the liquid level of the liquid in a container such as a water storage tank in a wider range and can be applied to a plurality of containers, as compared with the water level sensor described in Patent Document 1.

Means for Solving the Problems

[0006] As a result of intensive research to solve the above problems, the inventors of the present invention have succeeded in creating a liquid level detection system having a ventilation pipe, a gas supply means, a pressure measurement means, and a solenoid valve as basic elements to solve the problems of the present invention. The present invention has been completed based on such a successful example first made by the inventors.

[0007] That is, according to one aspect of the present invention, there is provided a liquid level detection system for detecting the liquid level of a liquid in a container, the liquid level detection system includes a ventilation pipe, a gas supply means, a pressure measurement means, and a solenoid valve, one end of the ventilation pipe can be arranged in the liquid in the container, the gas supply means can supply gas from the other end of the ventilation pipe, the pressure measurement means is arranged between one end and the other end of the ventilation pipe and can measure the pressure in the ventilation pipe, and the solenoid valve is arranged between the portion where the pressure measurement means of the ventilation pipe is arranged and the other end, and can open and close the ventilation pipe, and the liquid level detection system is provided.

[0008] According to another aspect of the present invention, there is provided a liquid level detection system for detecting the liquid level of a liquid in a container, the liquid level detection system includes a plurality of ventilation pipes, a gas supply means, a plurality of pressure measurement means, and a plurality of solenoid valves, one end of each of the plurality of ventilation pipes can be arranged in the liquid in the container, the gas supply means can supply gas from each of the other ends of the plurality of ventilation pipes, each of the plurality of pressure measurement means is arranged between one end and the other end of each of the plurality of ventilation pipes and can measure the pressure in the ventilation pipe, and each of the plurality of solenoid valves is arranged between the portion where the pressure measurement means of each of the plurality of ventilation pipes is arranged and the other end, and can open and close the ventilation pipe, and the liquid level detection system is provided.

[0009] According to another aspect of the present invention, there is provided a liquid level detection system for detecting the liquid level of a liquid in a container, the liquid level detection system includes a ventilation pipe, a gas supply means, a pressure measurement means, a plurality of electromagnetic valves, and a valve, the ventilation pipe has a branch portion where one end side branches, and each of the branched one ends can be arranged in the liquid in the container, the gas supply means can supply gas from the other end of the ventilation pipe, the pressure measurement means is arranged between the branch portion and the other end of the ventilation pipe, and can measure the pressure in the ventilation pipe, the plurality of electromagnetic valves are respectively arranged between the branch portion of the ventilation pipe and each of the branched one ends, and can open and close the ventilation pipe, and the valve is arranged between the portion where the pressure measurement means of the ventilation pipe is arranged and the other end, and can open and close the ventilation pipe, and the liquid level detection system is provided.

[0010] The valve is preferably an electromagnetic valve.

Advantages of the Invention

[0011] According to the present invention, by measuring the pressure in the ventilation pipe, the liquid level of the liquid in the container can be detected over a wider range. Further, according to the present invention, when measuring the pressure in the ventilation pipe, after removing (draining the liquid) the liquid held in the ventilation pipe from the other end by the gas supply means, by measuring the pressure in the ventilation pipe, the liquid level of the liquid in the container can be detected more accurately. Also, by using a plurality of ventilation pipes or a ventilation pipe with one end branched, and appropriately switching by a plurality of electromagnetic valves, without using a plurality of pressure measurement means, the liquid levels of the liquids in a plurality of respective containers can be detected over a wide range and accurately.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, details of each aspect of the present invention will be described, but the present invention can take various aspects as long as its object is achieved.

[0014] Each term in this specification is used in the meaning normally used by those skilled in the art such as the water treatment field unless otherwise specified, and should not be construed as having an unduly limiting meaning. Further, the assumptions and theories made in this specification are based on the inventors' so far knowledge and experience, and thus the present invention is not restricted only by such assumptions and theories.

[0015] "Comprise", "contain", and "include" mean that elements other than those explicitly stated as being included can be added (synonymous with "at least include"), and include "consist of" and "essentially consist of". That is, "comprise" can mean including the explicitly stated elements and any one or two or more elements, consisting of the explicitly stated elements, or essentially consisting of the explicitly stated elements. "Have" is synonymous with "comprise". Elements include limitations such as parts, means, components, steps, conditions, parameters, etc. "And / or" means any one of the listed multiple related items, or any combination or all combinations of two or more. The "~" in a numerical range is a range that includes the numerical values before and after it, and also includes a range excluding one of the included limit values. For example, "0%~100%" can be any of 0% or more, 100% or less, and 0% or more and 100% or less. "A plurality of" means two or more, for example, 2, 3, 4, 5, 6, 7, 8, 9, or 10, or 15 or 20.

[0016] Each aspect of the present invention will be described based on the drawings. In each drawing, those with low relevance to the present invention are omitted from illustration. In each drawing, the direction indicated by the arrow UP (→UP) shown as appropriate is taken as the upper side in the vertical direction.

[0017] [Overview of Liquid Level Detection System] The liquid level detection system comprises a vent pipe, a gas supply means, a pressure measurement means, and a solenoid valve as basic elements.

[0018] When measuring the liquid level using hydraulic pressure, in order to accurately measure the liquid level, it is necessary to remove the liquid that has entered the vent pipe. Therefore, the liquid in the vent pipe is drained by the gas pressure of the gas supplied by the gas supply means from the upstream in the vent pipe. After draining the liquid, by switching with the solenoid valve, the supply path of the gas supplied from the gas supply means is blocked, and the liquid pressure in the vent pipe is measured by the pressure measuring means. In such a liquid level detection system, by using a solenoid valve, a series of operations and configurations are simplified, and the design freedom is increased.

[0019] For example, it is conceivable to use a check valve instead of a solenoid valve. However, when there are a plurality of containers and measuring the liquid level of each container, in the case of a check valve, the gas supplied from the gas supply means is likely to escape to the vent pipe connected to the container with a low liquid level where the liquid pressure is low, and there may arise a problem that the liquid in all containers cannot be drained sufficiently. Since it is possible to control the throttle with a solenoid valve, such a problem related to the check valve can be solved.

[0020] Even when there are a plurality of containers and the liquids contained in the containers, by using a corresponding plurality of solenoid valves, it becomes possible to measure the liquid level of each liquid in the plurality of containers using the gas supply means and the pressure measuring means. As a result, the number of devices related to the gas supply means and the pressure measuring means can be reduced, and the liquid level detection system can be configured economically advantageously.

[0021] The container may be any container for containing a liquid and is not particularly limited. For example, when detecting the liquid level of the liquid in the container, it is preferably a container having a structure capable of fixing the vent pipe to such an extent that the pressure in the container can be stably measured.

[0022] Examples of the liquid include, but are not limited to, water such as domestic wastewater, industrial wastewater, sewage, rainwater, and tap water.

[0023] The liquid level refers to the height from the inner bottom surface of the container to the liquid surface in the container.

[0024] When the liquid is water, the container and the liquid level may be referred to as a water tank and a water level, respectively.

[0025] The liquid level detection system is used to detect the liquid level of the liquid in the container. The liquid level detection system may also be referred to as a liquid level sensor. By using the liquid level detection system, the liquid level of the liquid in the container can be quantitatively known in numerical values, a certain range, etc., or qualitatively known in relative scales (high, low, etc.). The liquid level detection system may be provided with warning means for issuing a warning to report that it is not within a predetermined liquid level range based on the detected liquid level.

[0026] [Liquid level detection system of the first aspect] The liquid level detection system of the first aspect includes one vent pipe, one gas supply means, one pressure measurement means, and one electromagnetic valve respectively. For the liquid level detection system of the first aspect, a part including one end of the vent pipe is placed in the liquid in the container, and then gas supplied by the gas supply means is introduced from the other end of the vent pipe to drain the liquid in the vent pipe (liquid drainage). Then, the other end side of the vent pipe is closed by the electromagnetic valve. Then, the pressure in the vent pipe between one end of the vent pipe and the electromagnetic valve is measured by the pressure measurement means, and the liquid level of the liquid in the container is detected by converting the pressure into a liquid level.

[0027] The liquid level detection system of the first aspect will be described with reference to FIG. 1 as an illustration. The liquid level detection system 1 includes a vent pipe 10, a gas supply means 11, a pressure measurement means 12, and an electromagnetic valve 13 as components. The liquid level detection system 1 may further include a control means 14 for controlling the opening and closing of the electromagnetic valve 13. The electromagnetic valve 13 and the control means 14 may be connected by wire or wirelessly.

[0028] The vent pipe 10 has a hollow structure so that fluids such as gas and liquid can move through it. The vent pipe 10 may be arranged in the container as long as the pressure inside the pipe varies according to the liquid level, and other characteristics are not particularly limited. Regarding other characteristics of the vent pipe 10, non-limiting examples of characteristics will be described below.

[0029] Examples of the material of the ventilation pipe 10 include plastic materials such as polytetrafluoroethylene, silicon, silicone, and rubber; metal materials such as stainless steel, titanium, and aluminum; and inorganic materials such as ceramics.

[0030] From the viewpoints of fluid flow and pressure loss, for example, the diameter of the ventilation pipe 10 is preferably 1 mm to 50 mm.

[0031] The ventilation pipe 10 is arranged such that a portion including one end 101 is placed in the liquid in the container, and the other end 102 is arranged such that gas can be supplied from the gas supply means 11 into the ventilation pipe 10. One end 101 of the ventilation pipe 10 only needs to have a hollow structure similar to the main body of the ventilation pipe 10 and does not need to be equipped with a mechanical water level sensor or the like. That is, when the ventilation pipe 10 is a silicone tube, one end 101 is the tip of the silicone tube.

[0032] The gas supply means 11 only needs to function so as to discharge the liquid in the ventilation pipe 10 from one end 101. The gas supplied from the gas supply means 11 only needs to have a low solubility in liquids such as water to the extent that it can extrude the liquid in the ventilation pipe 10 and is not particularly limited. For example, since it has little influence on the liquid in the container, air, nitrogen, carbon dioxide, etc. are preferred, and air is more preferred. The gas supply means 11 can be, for example, a blower, a gas cylinder, or the like.

[0033] A pressure measuring means 12 is arranged between one end 101 and the other end 102 of the ventilation pipe 10 so that the pressure in the ventilation pipe 10 can be measured. The pressure measuring means can also be called a pressure sensor. In the ventilation pipe 10, the portion where the pressure measuring means 12 is arranged is called a pressure measuring portion 103. The pressure measuring means 12 detects the pressure of the ventilation pipe 10 in the pressure measuring portion 103 and outputs it as a pressure value. The liquid level of the liquid in the container is obtained by converting the pressure value output by the pressure measuring means 12. The pressure measuring means 12 may be equipped with a function of converting the measured pressure into a liquid level, or may further output the converted liquid level. Note that based on the capacity and dimensions of the container, the water level based on the water pressure can be calculated.

[0034] A solenoid valve 13 is arranged between the pressure measurement section 103 and the other end 102 of the ventilation pipe 10. The solenoid valve 13 has a structure capable of electrically opening and closing the ventilation pipe 10. In the ventilation pipe 10, the portion where the solenoid valve 13 is arranged is called an opening / closing section 104. When the solenoid valve 13 is in an open state, fluid moves in the opening / closing section 104 of the ventilation pipe 10. When the solenoid valve 13 is in a closed state, the movement of the fluid is blocked in the opening / closing section 104 of the ventilation pipe 10. The control of the opening and closing of the solenoid valve 13 is not particularly limited. For example, it may be controlled by a control means 14. By using the control means 14, the degree of opening and closing (for example, 80% opening, etc.) can be controlled. The solenoid valve 13 is preferably arranged near the pressure measurement section 103 in order to suppress pressure fluctuations in the ventilation pipe 10. Incidentally, if the gas supply means 11 itself has a function of blocking or switching the inflow and outflow of gas, the solenoid valve 13 arranged between the pressure measurement section 103 and the other end 102 of the ventilation pipe 10 can be omitted.

[0035] An embodiment of detecting the liquid level of the liquid in the container using the liquid level detection system 1 is illustrated in FIG. 2. In FIG. 2, one end 101 of the ventilation pipe 10 is arranged near the bottom surface of the container 15 containing the liquid 16. The liquid level D1 of the liquid 16 is detected using the liquid level detection system 1.

[0036] A method of detecting the liquid level of the liquid in the container using the liquid level detection system of the first embodiment is illustrated in FIG. 3 as a flowchart. Hereinafter, a method of detecting the liquid level of the liquid in the container using the liquid level detection system 1 will be described with reference to FIGS. 2 and 3.

[0037] When the solenoid valve 13 is not in an open state, it is made open (S101) by operating the control means 14 or the like.

[0038] Next, gas is supplied into the ventilation pipe 10 from the gas supply means 11 through the other end 102 of the ventilation pipe 10, and the liquid in the ventilation pipe 10 is discharged from one end 101 of the ventilation pipe 10 to perform liquid draining (S102).

[0039] Next, the solenoid valve 13 is closed (S103) by operating the control means 14 or the like.

[0040] Next, the pressure measuring means 12 measures the pressure in the ventilation pipe 10 (S104).

[0041] Next, the measured pressure is converted into the liquid level D1 (S105). When the pressure measuring means 12 has a liquid level conversion function, the pressure measured by the pressure measuring means 12 is converted into the liquid level D1. On the other hand, when the pressure measuring means 12 does not have a liquid level conversion function, the pressure output by the pressure measuring means 12 is converted into a liquid level using a conversion formula. In this way, the liquid level D1 of the liquid 16 in the container 15 is detected (S106).

[0042] [Liquid level detection system of the second aspect] The liquid level detection system of the second aspect includes a plurality of ventilation pipes, one gas supply means, a plurality of pressure measuring means, and a plurality of solenoid valves. The liquid level detection system of the second aspect detects the liquid levels of the liquids in a plurality of containers. The number of ventilation pipes may correspond to the number of containers containing the liquid whose liquid level is to be detected, and is not particularly limited. The number of pressure measuring means and the number of solenoid valves correspond to the number of ventilation pipes.

[0043] The liquid level detection system of the second aspect will be described by taking FIG. 4 related to the liquid level detection system 2 as an example when the number of containers containing the liquid whose liquid level is to be detected is 2, and accordingly the number of ventilation pipes, pressure measuring means, and solenoid valves are each 2. In FIG. 4, for the sake of convenience, the two containers, namely container 25a and container 25b, and the corresponding liquids 26a and 26b are shown.

[0044] The liquid level detection system 2 includes, as components, two vent pipes 20a and 20b, a gas supply means 21, two pressure measurement means 22a and 22b, and two electromagnetic valves 23a and 23b. The liquid level detection system 2 may further include a control means 24 for controlling the opening and closing of the electromagnetic valves 23a and 23b. The electromagnetic valves 23a and 23b and the control means 24 may be connected to each other independently, either by wire or wirelessly. Also, there may be a plurality of control means according to the number of electromagnetic valves.

[0045] The vent pipes 20a and 20b are arranged such that portions including their respective one ends 201a and 201b are placed in the respective liquids 26a and 26b in the containers 25a and 25b, and their respective other ends 202a and 202b are arranged such that gas can be supplied from the gas supply means 21 into the vent pipes. Note that the other ends 202a and 202b may be arranged at the gas supply means 21 after merging into one.

[0046] A pressure measurement means 22a is arranged between one end 201a and the other end 202a of the vent pipe 20a so as to be able to measure the pressure inside the vent pipe 20a. Similarly, a pressure measurement means 22b is arranged between one end 201b and the other end 202b of the vent pipe 20b so as to be able to measure the pressure inside the vent pipe 20b. In the vent pipes 20a and 20b, the portions where the pressure measurement means 22a and 22b are arranged are respectively referred to as pressure measurement portions 203a and 203b.

[0047] A solenoid valve 23a is disposed between the pressure measurement section 203a and the other end 202a of the ventilation pipe 20a. Similarly, a solenoid valve 23b is disposed between the pressure measurement section 203b and the other end 202b of the ventilation pipe 20b. In the ventilation pipes 20a and 20b, the portions where the solenoid valves 23a and 23b are disposed are respectively referred to as opening / closing sections 204a and 204b. The opening and closing of the solenoid valves 23a and 23b may be controlled by control means 24. In addition, when the gas supply means 21 itself has a function of blocking or switching the inflow and outflow of gas, the solenoid valve 23a disposed between the pressure measurement section 203a and the other end 202a of the ventilation pipe 20a, and / or the solenoid valve 23b disposed between the pressure measurement section 203b and the other end 202b of the ventilation pipe 20b may be omitted.

[0048] Similar to the liquid level detection system 1, the liquid level detection system 2 detects the liquid levels D2a and D2b of the liquids 26a and 26b in the containers 25a and 25b.

[0049] The liquid level detection system according to the second aspect is characterized in that the liquid levels D2a and D2b can be detected simultaneously because two pressure measurement means are provided in two ventilation pipes. However, the liquid level detection system according to the second aspect may detect the liquid levels D2a and D2b at different timings.

[0050] When detecting the liquid levels D2a and D2b simultaneously, the solenoid valves 23a and 23b are simultaneously opened to supply gas from the gas supply means 21 into the ventilation pipes 20a and 20b to drain the liquid, and then the solenoid valves 23a and 23b are simultaneously closed, and the pressures in the ventilation pipes 20a and 20b are measured by the pressure measurement means 22a and 22b.

[0051] When simultaneously opening solenoid valves 23a and 23b, the gas supplied from the gas supply means 21 is likely to escape into the ventilation pipes 20a or 20b connected to the low liquid level containers with low hydraulic pressure, and there is a possibility that the liquid drainage of either ventilation pipe becomes insufficient. Therefore, when the approximate difference between the liquid levels D2a and D2b is known, it is preferable to reduce the opening state of the solenoid valve at the lower liquid level to throttle so that sufficient liquid drainage can be achieved for both ventilation pipes 20a and 20b.

[0052] When detecting the liquid levels D2a and D2b at different times, for example, keep the solenoid valve 23b in the closed state, open the solenoid valve 23a, perform liquid drainage, pressure measurement and liquid level conversion to detect the liquid level D2a. Then, keep the solenoid valve 23a in the closed state, open the solenoid valve 23b, perform liquid drainage, pressure measurement and liquid level conversion to detect the liquid level D2b. Note that if the solenoid valve 23a is closed after liquid drainage, before detecting the liquid level D2a, the solenoid valve 23b can be opened to drain the liquid in the ventilation pipe 20b.

[0053] [Liquid level detection system of the third aspect] The liquid level detection system of the third aspect includes one ventilation pipe having a branch portion where one end side branches, one gas supply means, one pressure measurement means, a plurality of solenoid valves, and one valve. The liquid level detection system of the third aspect detects the liquid levels of the liquids in a plurality of containers. The number of branches of the ventilation pipe may correspond to the number of containers containing the liquid whose liquid level is to be detected, and is not particularly limited. The number of solenoid valves corresponds to the number of branches of the ventilation pipe.

[0054] The liquid level detection system of the third aspect is characterized in that the ventilation pipe branches at one end side, and in addition to the plurality of solenoid valves provided according to the number of branches of the ventilation pipe, a valve is provided at the other end side of the ventilation pipe.

[0055] The ventilation pipe may branch so that the diameter, length, etc. are different, or may branch so that they are equal, but it is preferable that the diameter and / or length are equal when branching, and it is more preferable that the diameter and length are equal when branching.

[0056] The valve can be a solenoid valve, a check valve, or a valve with other structures, as long as it is provided on the other end side of the ventilation pipe and can open and close the ventilation pipe so as to control the flow of the fluid in the ventilation pipe, and is not particularly limited. Since the valve can be controlled together with another solenoid valve, it is preferably a solenoid valve.

[0057] Regarding the liquid level detection system of the third aspect, FIG. 5 related to the liquid level detection system 3 will be illustrated and described when the number of containers for containing the liquid for which the liquid level is to be detected is two, accordingly the number of branches of the ventilation pipe is two, and the number of solenoid valves is two. In FIG. 5, for the sake of convenience, the two containers, i.e., container 35a and container 35b, and the corresponding liquids 36a and 36b are shown.

[0058] The liquid level detection system 3 includes, as components, a ventilation pipe 30 with one end side branched, a gas supply means 31, a pressure measurement means 32, two solenoid valves 33a and 33b, and a valve 37. The liquid level detection system 3 may further include a control means 34 for controlling the opening and closing of the solenoid valves 33a and 33b, and in some cases, the opening and closing of the valve 37. The solenoid valves 33a and 33b and the valve 37 may be connected independently, either wired or wirelessly. Also, there may be a plurality of control means according to the number of solenoid valves and valves.

[0059] The ventilation pipe 30 has a branch portion 305 where one end side branches, and the portions including the respective one ends 301a and 301b after branching are arranged to be placed in the respective liquids 36a and 36b in the containers 35a and 35b. The other end 302 of the ventilation pipe 30 is arranged so that gas can be supplied from the gas supply means 31 into the ventilation pipe.

[0060] A pressure measurement means 32 is arranged between the branch portion 305 and the other end 302 of the ventilation pipe 30 so that the pressure in the ventilation pipe 30 can be measured. In the ventilation pipe 30, the portion where the pressure measurement means 32 is arranged is called a pressure measurement portion 303.

[0061] A solenoid valve 33a is disposed between a branch portion 305 of the ventilation pipe 30 and one end portion 301a branched therefrom. Similarly, a solenoid valve 33b is disposed between the branch portion 305 of the ventilation pipe 30 and one end portion 301b branched therefrom. In the ventilation pipe 30, portions where the solenoid valves 33a and 33b and the valve 37 are disposed are referred to as an opening / closing portion 304a, an opening / closing portion 304b, and an opening / closing portion 307, respectively. The opening and closing of the solenoid valves 33a and 33b may be controlled by a control means 34.

[0062] A valve 37 is disposed on the side of the other end portion 302 of the ventilation pipe 30. The valve 37 is disposed between a pressure measurement portion 303 of the ventilation pipe 30 and a gas supply means 31. The valve 37 has an opening / closing structure and can open and close the ventilation pipe 30. When the valve 37 is a solenoid valve, the opening and closing thereof may be controlled by the control means 34. Note that when the gas supply means 31 itself has a function of blocking or switching the inflow and outflow of gas, the valve 37 disposed between the pressure measurement portion 303 of the ventilation pipe 30 and the gas supply means 31 may be omitted.

[0063] The liquid level detection system 3 detects the liquid levels D3a and D3b of the liquids 36a and 36b in the containers 35a and 35b in the same manner as the liquid level detection systems 1 and 2. However, different from the liquid level detection system 2, the liquid level detection system 3 cannot detect the liquid levels D3a and D3b simultaneously.

[0064] In the liquid level detection system 3, when draining the liquid, the valve 37 is opened before, after, or simultaneously with opening the solenoid valve 33a and / or the solenoid valve 33b. After draining the liquid, it is preferable to close the valve 37 and then close the solenoid valve 33a and / or the solenoid valve 33b.

[0065] For example, when detecting the liquid level D3a, after opening the valve 37, open the solenoid valve 33a, close the solenoid valve 33b, and supply gas from the gas supply means 31 into the ventilation pipe 30 to drain the liquid so that gas is discharged from one end 301a. Then, close the valve 37 and measure the pressure in the ventilation pipe 30 with the pressure measuring means 32. When detecting the liquid level D3b, reverse operations may be performed on the solenoid valve 33a and the solenoid valve 33b respectively.

Industrial Applicability

[0066] The liquid level detection system according to one aspect of the present invention has a simple configuration and can detect the liquid level of liquid in one or a plurality of containers over a wide range. Therefore, it can be used, for example, for detecting the liquid level in a self-circulating water purification device.

Explanation of Reference Numerals

[0067] 1, 2, 3 Liquid level detection system 10, 20a, 20b, 30 Ventilation pipe 101, 201a, 201b, 301a, 301b One end 102, 202a, 202b, 302 The other end 103, 203a, 203b, 303 Pressure measurement unit 104, 204a, 204b, 304a, 304b, 307 Opening / closing unit 11, 21, 31 Gas supply means 12, 22a, 22b, 32 Pressure measurement means 13, 23a, 23b, 33a, 33b Solenoid valve 14, 24, 34 Control means 15, 25a, 25b, 35a, 35b Container 16, 26a, 26b, 36a, 36b Liquid 37 Valve D1, D2a, D2b, D3a, D3b Liquid level

Claims

1. A liquid level detection system for detecting the liquid level of a liquid in a container, wherein the liquid level detection system includes a ventilation pipe, a gas supply means, a pressure measurement means, and a solenoid valve, one end of the ventilation pipe can be arranged in the liquid in the container, the gas supply means can supply gas from the other end of the ventilation pipe, the pressure measurement means is arranged between one end and the other end of the ventilation pipe and can measure the pressure in the ventilation pipe, and the solenoid valve is arranged between the portion of the ventilation pipe where the pressure measurement means is arranged and the other end, and can open and close the ventilation pipe, the liquid level detection system.

2. A liquid level detection system for detecting the liquid level of a liquid in a container, wherein the liquid level detection system includes a plurality of ventilation pipes, a gas supply means, a plurality of pressure measurement means, and a plurality of solenoid valves, one end of each of the plurality of ventilation pipes can be arranged in the liquid in the container, the gas supply means can supply gas from the other end of each of the plurality of ventilation pipes, each of the plurality of pressure measurement means is arranged between one end and the other end of each of the plurality of ventilation pipes and can measure the pressure in the ventilation pipe, and each of the plurality of solenoid valves is arranged between the portion of each of the plurality of ventilation pipes where the pressure measurement means is arranged and the other end, and can open and close the ventilation pipe, the liquid level detection system.

3. A liquid level detection system for detecting the liquid level of a liquid in a container, wherein the liquid level detection system includes a ventilation pipe, a gas supply means, a pressure measurement means, a plurality of solenoid valves, and a valve, the ventilation pipe has a branch portion where one end side branches, and each branched one end can be arranged in the liquid in the container, the gas supply means can supply gas from the other end of the ventilation pipe, the pressure measurement means is arranged between the branch portion and the other end of the ventilation pipe and can measure the pressure in the ventilation pipe, each of the plurality of solenoid valves is arranged between the branch portion of the ventilation pipe and each branched one end and can open and close the ventilation pipe, and the valve is arranged between the portion of the ventilation pipe where the pressure measurement means is arranged and the other end, and can open and close the ventilation pipe, the liquid level detection system.

4. The liquid level detection system according to claim 3, wherein the valve is a solenoid valve.

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