Floatless liquid level sensor

Abstract

To solve the problems with an electrode type liquid level meter, that electrode bars are heavy making installation and cleaning work troublesome, and that malfunction due to contact between electrode bars, and malfunction due to attachment of trash to a separator occur.SOLUTION: An electrode installed at the lowermost position, as a common electrode, clamps a three-core VA cable from the front and the back using two fasteners, and is tightened with two bolts, and a sharp-pointed truss screw is screwed into a center part of the fastener, and the electrode is caused to contact an electric wire in the middle of the three-core cable. Further, an electrode connected at an upper position of the three-core cable on an opposite side of a side where the common electrode is connected, is fastened with fasteners as described above, and a sharp-pointed truss screw is screwed slightly sideways of a center part of the fastener, and the electrode is caused to contact either the left or right electric wire of the three cores. Two electrodes are caused to respectively contact the left and right electric wires of the three-core cable. Accordingly, an electrode of a liquid level sensor detects a liquid level in a container on the basis of conduction occurring when the common electrode and the two electrodes at the upper positions are soaked in liquid.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a floatless liquid level sensor.

Background Art

[0002] Liquid level sensors include float type, electrode type, capacitance type, etc. The float type has a float that moves up and down based on the principle of buoyancy, and a reed switch is actuated by a magnet inside the float to output a detection signal. The electrode type has a current flowing between electrodes when a conductive liquid touches between the electrodes, and this is detected to output a detection signal. The capacitance type detects and measures the difference between the specific dielectric constant of a liquid and that of air, and outputs a detection and measurement signal. When the dielectric constant of the liquid changes greatly, it cannot be measured.

[0003] There is a float type liquid level gauge that floats a float on the liquid surface and detects the floating amount of the float up and down to know the height of the liquid level. A permanent magnet is provided inside the float, and an invention has been made that turns on and off a reed switch, etc. due to the change in magnetic flux caused by the floating of the float (Patent Document 1).

[0004] The disadvantages of the float type liquid level gauge are as follows. If dust or the like adheres to the surface of the float, it may not float. If the float is damaged, the liquid will enter and it will not float. The float may get caught on a pump or a scaffold (step) in the tank and not move up and down. Also, when wiring is done on the movable part of the float, it is easy to break due to repeated bending.

[0005] The electrode type liquid level gauge detects the height of the liquid level by electrical conductivity through the liquid between a plurality of electrode rods. The electrode type liquid level gauge attaches a plurality of electrode rods with different lengths to an electrode holder, and utilizes the fact that the lower ends of the electrode rods with different lengths come into contact with or separate from the liquid surface due to the rise or fall of the liquid level, and detects the position of the liquid level by the electrical conductivity due to the liquid connection between the electrode rods in contact with the liquid surface. An electrode type liquid level gauge has been invented that uses electrode rods with different lengths and whose surfaces are covered with an insulating tape leaving both ends (Patent Document 2). The electrode rod is usually a 6 - millimeter - diameter rod made of stainless steel, which is heavy and difficult to install and clean. And when the electrode rods come into contact with each other, malfunction occurs. Even if a separator is attached to separate the electrode rods, if dust or the like adheres to the separator, it will lead to malfunction. Therefore, the scope of use is restricted, such as it can only be used with clean tap water without dust.

[0006] As a prior art, there are a plurality of electrode parts (4 in the embodiment) installed by being connected to a single inorganic insulating cable, and a common electrode connected to the tip (the lowermost position) of the cable. A water level gauge (Patent Document 3) is invented, which is connected to the cable on the side opposite to the side where the common electrode is connected and measures the water level in the container based on the resistance value between each of the plurality of electrode parts and the common electrode. In that embodiment, 5 electric wires are bundled into an inorganic insulating cable. When the electrode parts at each measurement point are submerged, they are electrically connected to the common electrode part through water. In this case, the arrangement and wiring of the electrodes for measuring each water level are complex, the position of the measurement electrode cannot be easily changed, and it cannot be bent either.

[0007] Also, in the insulating material of a protective cylinder filled with an insulating material between an outer cylinder (synthetic resin) and an inner cylinder (synthetic resin), a plurality of divided electrode pieces are arranged with gaps in the length direction, and a small screw with a head is inserted from the outside of the protective tube so as to be insertable and removable and contact the electrode pieces. And by removing the small screw, liquid enters the small hole and contacts the electrode pieces to conduct electricity, and an electrode - type liquid level gauge has been invented (Patent Document 4). First, arranging a plurality of electrode pieces with gaps in the length direction in the insulating material of the protective cylinder so that they do not contact each other is difficult. Second, since the small screw is in contact with the electrode pieces, a metal such as iron with conductivity cannot be used for the small screw. Third, there is a possibility that this small hole may be clogged with dust or the like, causing trouble that the electrode pieces do not contact the liquid. First, it is difficult to arrange a plurality of electrode pieces in the insulating material (rubber or synthetic resin) of the protective cylinder with gaps in the length direction so that they do not contact each other. Second, since the small screw is in contact with the electrode pieces, a metal such as iron with conductivity cannot be used for the small screw. Third, there is a possibility that this small hole may be clogged with dust or the like, causing trouble that the electrode pieces do not contact the liquid.

Prior - art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] There is a float-type liquid level gauge that floats a float on the liquid surface and detects the height of the liquid surface by detecting the amount of up and down floating of the float. There has been an invention in which a permanent magnet is provided inside the float, and a reed switch or the like is turned on and off by a change in magnetic flux due to the floating of the float. The float type is often used in sewage tanks, but it frequently causes problems such as garbage adhesion, floating failure due to float breakage, and disconnection. When garbage or the like adheres to the surface of the float, it may not float. When the float is damaged, the liquid enters and it no longer floats. The float may get caught on a pump or a scaffold (step) inside the tank and not move up and down. Also, when wiring is done on the movable part of the float, it is likely to break due to repeated bending. The electrode type liquid level gauge detects the height of the liquid surface by electrical conduction through the liquid between a plurality of electrode rods. The electrode type liquid level gauge attaches a plurality of electrode rods with different lengths to an electrode holder, and utilizes the fact that the lower ends of the electrode rods with different lengths come into contact with or separate from the liquid surface due to the rise or fall of the liquid surface, and detects the position of the liquid surface by electrical conduction through the liquid junction between the electrode rods in contact with the liquid surface. There has been an invention of an electrode type liquid level gauge that uses electrode rods with different lengths, with the surface covered with insulating tape except for both ends. The electrode rod is usually a 6 - millimeter - diameter rod made of stainless steel, which is heavy and makes installation and cleaning work difficult. And when electrode rods come into contact with each other, malfunction occurs. Even if a separator is attached to separate the electrode rods, if dust or the like adheres to the separator, it will lead to malfunction. For this reason, the scope of use is restricted, such as it can only be used with clean tap water without dust.

[0010] There are a plurality of electrode parts (4 in the embodiment) connected and installed to a single inorganic insulating cable, and a common electrode connected to the tip (the lowest position) of the cable. A water level gauge is invented that measures the water level in a container based on the resistance value between each of the plurality of electrode parts and the common electrode on the side of the cable opposite to the side where the common electrode is connected. In that embodiment, 5 electric wires are bundled into an inorganic insulating cable. When the electrode part at each measurement point is submerged, it is electrically connected to the common electrode part through water. In this case, the arrangement and wiring of the electrodes for measuring each water level are complex, the position of the measurement electrode cannot be easily changed, and it cannot be bent either. A liquid - level sensor is required that is easy to install, allows the position of the liquid - level detection electrode to be easily changed, is not easily damaged, and can be bent.

[0011] And in the insulating material of a protective cylinder filled with an insulating material between an outer cylinder (synthetic resin) and an inner cylinder (synthetic resin), a plurality of divided electrode pieces are arranged with a gap in the length direction, and a small screw with a head is inserted from the outside of the protective tube so as to be insertable and removable and contact the electrode piece. By removing the small screw, liquid enters through a small hole and contacts the electrode piece, and an electrode - type liquid - level gauge that conducts electricity is invented. In the insulating material of the protective cylinder, a plurality of electrode pieces are arranged with a gap in the length direction. And screw holes are provided in the gap between the electrode pieces for screwing a small screw with a head from the outside of the protective tube. The contact between the liquid and the electrode is carried out through a small screw hole passing through the electrode piece. First, it is difficult to arrange a plurality of electrode pieces in the insulating material (rubber or synthetic resin) of the protective cylinder with a gap in the length direction so that they do not contact each other. Also, since the small screw is in contact with the electrode piece, a metal such as iron with conductivity cannot be used for the small screw. And this small hole may be clogged with dust or the like, causing a problem that the electrode piece does not come into contact with the liquid. There is a need for a liquid level sensor for sewage, wastewater, drainage, tap water, etc. that can be easily installed with a simple device and is not troubled by dust, scale, floating matter, etc.

Means for Solving the Problem

[0012] In the electrode of a liquid level sensor composed of a metal fastener, a hexagonal wrench cap bolt that tightens at both ends of the fastener, a pointed truss screw, and a packing, two pieces of the metal fastener sandwich a three-core VA cable from the front and back, and two places at the central parts of both ends of the fastener are tightened with two hexagonal wrench cap bolts. The pointed truss screw is screwed into the central part of the fastener and brought into contact with the single copper wire in the middle of the three-core cable to serve as an electrode. A packing is attached to the truss screw to prevent liquid from entering between it and the fastener. It can be installed at the lowest position of the three-core cable and used as a common electrode, or as the lowest electrode at the end of another three-core cable. It is an electrode of a floatless liquid level sensor in which the wire end of the three-core cable with an electrode is sealed with silicone caulking to prevent contact between the liquid and the wire. The three-core VA cable is a flat cable in which single copper wires are coated with vinyl resin instead of twisted wires, and then three coated copper wires are arranged side by side and coated with vinyl resin. This three-core cable is a general-purpose product, can be obtained at an ordinary store, and is inexpensive. Usually, it is coated with polyvinyl chloride resin, but it can also be coated with Teflon (registered trademark) resin or the like to increase chemical resistance. The metal fasteners, the cap bolts for a hexagonal wrench to tighten at both ends of the fasteners, and the pointed truss screws are made of stainless steel, SUS316, which is not easily corroded. These parts may also be SUS304. When higher corrosion resistance is required, titanium, Hastelloy (HASB, HASC) (a trademark of Haynes, USA), etc. are used. The packing (gasket) is made of a material such as paper, and two sheets with a thickness of 0.5 millimeters are used. Two metal fasteners sandwich a three-core VA cable from the front and back. At two locations in the center of both ends of the fasteners, two cap bolts for a hexagonal wrench are used to apply pressure and tighten the cable until it deforms. The pointed truss screw is screwed into the center of the fastener with a plus driver and brought into contact with the wire in the middle of the three-core cable. A packing (gasket) is attached to the truss screw to prevent liquid from entering between the fastener and the electrode is attached to the three-core cable. This is because if liquid enters the wire through the truss screw, it will rise through the gap due to capillary action, corrode the wire, and cause a short circuit with other wires with electrodes in the three-core cable. Over time, it will reach the control panel and cause problems, so the liquid is prevented from entering the wires of the three-core VA cable.

[0013] In the electrode of the liquid level sensor composed of a metal fastener, the cap bolts for a hexagonal wrench to tighten at both ends of the fastener, the pointed truss screw, and the packing, two metal fasteners sandwich a three-core VA cable from the front and back. At two locations in the upper right and lower left of both ends of the fastener, two cap bolts for a hexagonal wrench are used to tighten. The pointed truss screw is screwed in slightly sideways at the center of the fastener and brought into contact with either the single copper wire on the left or right of the three-core cable to serve as an electrode. Reversing the left and right of this electrode allows contact with the wire of the other three-core cable. A packing is attached to the truss screw to prevent liquid from entering between the fastener and the electrode. This electrode is for a floatless liquid level sensor installed above the three-core cable to detect the liquid level. At two locations, namely the upper right and lower left at both ends of the stopper, tighten with two cap bolts for a hex wrench. Screw the pointed truss screw slightly to the side of the center of the stopper and bring it into contact with either the left or right wire of the three-core cable to use it as an electrode. By bringing the bolt holes closer to the upper right and lower left at both ends of the stopper and devising to reduce the size of the stopper so that the head of the bolt and the head of the truss screw do not overlap. Of course, bolt holes can also be opened at the upper left and lower right at both ends of the stopper. If the electrode is large, dust can get caught and malfunction easily, but if the electrode is small, dust will not adhere.

[0014] In the electrode of the liquid level sensor composed of a metal stopper, cap bolts for a hex wrench tightened at both ends of the stopper, a pointed truss screw, and a packing, sandwich the three-core VA cable from the front and back with two pieces of metal stoppers, tighten two cap bolts for a hex wrench at two locations in the center of both ends of the stopper, screw the pointed truss screw slightly to the side of the center of the stopper from the direction opposite to the cap bolt (back side), bring it into contact with either the single-strand copper wire on the left or right of the three-core cable to use it as an electrode, and if the left and right of the electrode are reversed, it can be brought into contact with the wire of the other three-core cable. A packing is attached to the truss screw to prevent liquid from entering between the stopper and the truss screw. This electrode is the electrode of a floatless liquid level sensor installed at the position above the three-core cable to detect the liquid level. Screw the pointed truss screw slightly to the side of the center of the stopper from the direction opposite to the cap bolt (back side) and bring it into contact with either the left or right wire of the three-core cable to use it as an electrode. By screwing the truss screw from the direction opposite to the cap bolt (back side), it is possible to avoid the overlap of the head of the cap bolt and the head of the truss screw and reduce the size of the electrode. As a result, dust does not adhere to the electrode.

[0015] In a liquid level sensor that detects using an electrode in which the liquid level inside the container is tightened with two hexagon wrench cap bolts at two places, upper right and lower left, at both ends of a stopper installed at the upper position and the common electrode of the electrode at the lowest position, or an electrode in which two places at the center of both ends of the stopper are tightened with two hexagon wrench cap bolts, and a pointed truss screw is screwed in slightly to the side of the center of the stopper, or an electrode in which two places at the center of both ends of the stopper are tightened with two hexagon wrench cap bolts, and a pointed truss screw is screwed in slightly to the side of the center of the stopper from the direction (back side) opposite to the cap bolt. A three-core VA cable is sandwiched from the front and back with two pieces of stoppers, two places at the center of both ends of the stopper are tightened with two hexagon wrench cap bolts, a pointed truss screw is screwed into the center of the stopper and brought into contact with the middle wire of the three-core cable. The electrode is installed at the lowest position of the three-core cable, and with the electrode at the lowest position as the common electrode, it is connected to a position above the cable on the side opposite to the side to which the common electrode is connected. The three-core VA cable is sandwiched from the front and back with two pieces of the above-mentioned metal stoppers, and two places, upper right and lower left, at both ends of the stopper installed at the upper position are tightened with two hexagon wrench cap bolts, and two pointed truss screws are screwed in slightly to the side of the center of the stopper and brought into contact with the left and right wires of the three-core cable respectively, or the three-core VA cable is sandwiched from the front and back with two pieces of the above-mentioned metal stoppers, two places at the center of both ends of the stopper are tightened with two hexagon wrench cap bolts, and two pointed truss screws are screwed in slightly to the side of the center of the stopper from the direction (back side) opposite to the cap bolt and brought into contact with the left and right wires of the three-core cable respectively. If the common electrode and the two electrodes (upper limit position, lower limit position) at the upper position are immersed in the liquid, they conduct, and if they are not immersed in the liquid, they do not conduct. Therefore, it is a detection method of a floatless liquid level sensor that detects the liquid level inside the container based on the conduction between these two electrodes and the common electrode.

[0016] In a liquid level sensor that detects using an electrode in which the liquid level in the container is tightened with two hexagon wrench cap bolts at two upper right and lower left positions at both ends of a stopper installed at the upper position and the common electrode of the electrode at the lowest position, or an electrode in which two hexagon wrench cap bolts are tightened at two central positions at both ends of the stopper, and a pointed truss screw is screwed slightly sideways to the central part of the stopper, or an electrode in which two hexagon wrench cap bolts are tightened at two central positions at both ends of the stopper, and a pointed truss screw is screwed slightly sideways to the central part of the stopper from the direction (back side) opposite to the cap bolt. A three-core VA cable is sandwiched from the front and back with two pieces of stoppers, two hexagon wrench cap bolts are tightened at two central positions at both ends of the stopper, a pointed truss screw is screwed into the central part of the stopper and brought into contact with the middle wire of the three-core cable, and the electrode is installed at the lowest position of the three-core cable. Using the electrode at the lowest position as a common electrode, it is connected to the upper position of the three-core cable on the side opposite to the side to which the common electrode is connected. The three-core VA cable is sandwiched from the front and back with two pieces of the above-mentioned metal stoppers, and two electrodes in which two hexagon wrench cap bolts are tightened at two upper right and lower left positions at both ends of the stopper installed at the upper position and a pointed truss screw is screwed slightly sideways to the central part of the stopper are brought into contact with the left and right wires of the three-core cable respectively, or the three-core VA cable is sandwiched from the front and back with two pieces of the above-mentioned metal stoppers, two hexagon wrench cap bolts are tightened at two central positions at both ends of the stopper, and two electrodes in which a pointed truss screw is screwed slightly sideways to the central part of the stopper from the direction (back side) opposite to the cap bolt are brought into contact with the left and right wires of the three-core cable respectively. Install yet another three-core VA cable inside the container, sandwich the three-core VA cable from the front and back with two clips, tighten two hex wrench cap bolts at two central positions at both ends of the clip, screw a pointed truss screw into the central part of the clip, install an electrode that contacts the middle wire of the three-core cable at the lowest position of the three-core cable, seal the wire ends of the three-core cable with this electrode with silicone caulking to prevent contact between the liquid and the wire, tighten two hex wrench cap bolts at two upper right and lower left positions at both ends of the above clip, screw a pointed truss screw slightly sideways into the central part of the clip, or tighten two hex wrench cap bolts at two central positions at both ends of the above clip, and screw a pointed truss screw slightly sideways into the central part of the clip from the direction (back side) opposite to the cap bolt and install it at a position above the three-core cable, which functions as sensors for the lower limit position and the upper limit position respectively. Since the common electrode and the four electrodes at the upper position (upper limit position, lower limit position, upper limit boundary position, lower limit boundary position) conduct electricity when immersed in the liquid and do not conduct electricity when not immersed in the liquid, this is a detection method of a floatless liquid level sensor for detecting the liquid level in the container based on the conduction between these four electrodes and the common electrode. As described above, when it is desired to increase the number of detection positions, a plurality of three-core cables can be used to increase the number of electrodes to be detected.

[0017] When changing the position of the electrode to be detected, loosen the two hex wrench cap bolts at two places, loosen the pointed truss screw and move it on the three-core cable. Then, at the new position, tightly tighten the hex wrench cap bolt and the pointed truss screw. The hole of the truss screw at the previous position is filled with silicone caulking. Alternatively, the clip and the truss screw can be completely removed and reinstalled at the new position.

[0018] In this liquid level sensor, apply an AC voltage of about 8V to the electrode, extract the signal and process it with a control panel.

[0019] This liquid level sensor can be used for conductive liquids. It is mainly used in tanks for sewage, wastewater, drainage, and tap water. Since it can be used for conductive liquids, it can also be utilized in industries such as the chemical industry and the food industry.

Advantages of the Invention

[0020] This liquid level sensor is easy to install. By using a hex wrench and a Phillips screwdriver to install the sandwich electrodes on the three-core VA cable from the front and back, no working power supply is required during installation, and no application for permission to use fire is needed. The position of the electrodes is determined by the distance from the bottom of the tank. The common electrode is installed at the lowest position, and the electrodes at the upper positions are installed sequentially. Although the electrodes can be attached to the three-core cable on-site, since it is light and easy to carry, the electrodes can be pre-attached and then the three-core cable can be extended and installed on-site. It can be used even for small-capacity tanks and can be installed on the inner wall surface of the tank. When using several three-core cables, they can be fixed with a binding band for construction. Even for a tank with a slanted ceiling, since the three-core cable can be bent, it can be bent at the attachment part and installed vertically. During the cleaning operation, the three-core cable can be pulled up from the tank, cleaned, and the electrodes can be inspected. Since the electrodes are made as small as possible, almost no dust adheres to them. As described above, the electrodes of this liquid level sensor are mainly used in tap water tanks, sewage, wastewater, and drainage tanks, and can also be used for conductive liquids, so they can also be utilized in industries such as the chemical industry and the food industry. The installation work is simple, and the cleaning work is also easy.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0022] Examples of the present invention are shown below. The present invention is not limited to these examples.

Examples

[0023] FIG. 1 shows an exploded view of an electrode that can be installed at the lowermost position of a three-core cable (5) and used as a common electrode or the lowermost electrode at the end of another three-core cable. In the electrode of the liquid level sensor composed of a metal fixture (1), a hexagonal wrench cap bolt (2) that tightens at both ends of the fixture (1), a pointed truss screw (3), and a packing (4), the three-core VA cable (5) is sandwiched from the front and back by two pieces of the metal fixture (1), and two places at the center of both ends of the fixture (1) are tightened with two hexagonal wrench cap bolts (2). The pointed truss screw (3) is screwed into the center of the fixture (1) and brought into contact with the single copper wire in the middle of the three-core cable (5) to form an electrode. A packing (4) is attached to the truss screw (3) to prevent liquid from entering between the fixture (1). It can be installed at the lowermost position of the three-core cable (5) and used as a common electrode or the lowermost electrode at the end of another three-core cable. The wire end of the three-core cable (5) with the electrode is sealed with silicon caulking to prevent contact with the liquid. It is an electrode of a floatless liquid level sensor. The three-core VA cable uses a flat three-core cable in which a single copper wire is coated with polyvinyl chloride resin and then these three are further coated with polyvinyl chloride resin. It is a general-purpose product, easy to obtain, and inexpensive. For the metal fixture, the cap bolt for a hexagonal wrench that is tightened at both ends of the fixture, and the pointed truss screw at the tip, stainless steel SUS316, which is difficult to corrode, was used. As the packing, commercially available sheet packing was cut into a round shape and used. Two sheets with a thickness of 0.5 millimeters were used.

Example

[0024] Figure 2 is an exploded view of the electrode installed above the three-core cable (5) and used as a liquid level detection electrode. In the electrode of the liquid level sensor composed of a metal fixture (1), a cap bolt (2) for a hexagonal wrench that is tightened at both ends of the fixture (1), a pointed truss screw (3), and a packing (4), the three-core VA cable (5) is sandwiched from the front and back by two pieces of the metal fixture (1), and the upper right and lower left two positions at both ends of the fixture (1) are tightened with two cap bolts (2) for a hexagonal wrench. The pointed truss screw (3) is screwed in slightly horizontally at the center of the fixture (1) and brought into contact with either the left or right single copper wire of the three-core cable (5) to serve as an electrode. When the left and right of this electrode are reversed, it can contact the wire of the other three-core cable (5). A packing (4) is attached to the truss screw (3) so that liquid does not enter between it and the fixture (1). This electrode is the electrode of a floatless liquid level sensor installed above the three-core cable (5) to detect the liquid level. Bolts (2) holes are brought closer to the upper right and lower left two positions at both ends of the fixture (1) so that the head of the bolt (2) and the head of the truss screw (3) do not overlap, and the size of the fixture (1) is made smaller. If the electrode is large, dust is likely to get caught and cause malfunction, but if the electrode is made smaller, dust will not adhere.

Example

[0025] Figure 3 is an exploded view of another electrode installed above the three-core cable (5) and used as a liquid level detection electrode. In the electrode of a liquid level sensor composed of a metal stopper (1), a hexagon wrench cap bolt (2) that tightens at both ends of the stopper (1), a pointed truss screw (3), and a packing (4), the three-core VA cable (5) is sandwiched from the front and back by two pieces of the metal stopper (1), and two locations at the center of both ends of the stopper (1) are tightened with two hexagon wrench cap bolts (2). The pointed truss screw (3) is screwed into a position slightly to the side of the center of the stopper from the direction opposite to the cap bolt (the back side), and is brought into contact with either the left or right single copper wire of the three-core cable to form an electrode. When the left and right of the electrode are reversed, it can contact the wire of the other three-core cable (5). A packing (4) is attached to the truss screw (3) to prevent liquid from entering between the stopper (1). This electrode is installed at a position above the three-core cable (5) and is the electrode of a floatless liquid level sensor that detects the liquid level. The pointed truss screw (3) is screwed into a position slightly to the side of the center of the stopper (1) from the direction opposite to the cap bolt (the back side), and is brought into contact with either the left or right wire of the three-core cable (5) to form an electrode. By screwing the truss screw (3) from the direction opposite to the cap bolt (the back side), it is possible to avoid the heads of the cap bolt (2) and the truss screw (3) overlapping and reduce the size of the electrode. As a result, dust does not adhere to the electrode.

Example

[0026] Figure 4 is a schematic front view of a liquid level detection sensor in which a single three-core cable (5) is installed in a container and a common electrode (6) and two liquid level detection electrodes (7) are attached. In a liquid level sensor for detecting the liquid level in a container by using an electrode (7) in which the liquid level in the container is tightened with two hexagon wrench cap bolts (2) at two upper right and lower left positions at both ends of a stopper (1) installed at the upper position and a common electrode (6) of the electrodes at the lowest position, and the pointed truss screw (3) is screwed in slightly to the side of the center of the stopper (1), a three-core VA cable (5) is sandwiched from the front and back by two stoppers (1), and two positions at the center of both ends of the stopper (1) are tightened with two hexagon wrench cap bolts (2). The pointed truss screw (3) is screwed into the center of the stopper (1) and contacts the middle wire of the three-core cable (5). The electrode is installed at the lowest position of the three-core cable (5). With the lowest-position electrode as the common electrode (6), it is connected to the position above the three-core cable (5) on the side opposite to the side to which the common electrode (6) is connected. Two electrodes (7) tightened with two hexagon wrench cap bolts (2) at two upper right and lower left positions at both ends of the stopper (1) installed at the above upper position are brought into contact with the left and right wires of the three-core cable (5) respectively. If the common electrode (6) and the two electrodes (upper limit position, lower limit position) at the upper position are immersed in the liquid, they will conduct electricity, and if they are not immersed in the liquid, they will not conduct electricity. Therefore, based on the conduction between these two electrodes (7) and the common electrode (6), this is a detection method for a floatless liquid level sensor that detects the liquid level in the container.

Example

[0027] Figure 5 is a schematic front view of a liquid level detection sensor in which a single three-core cable (5) is installed in a container and a common electrode (6) and two other liquid level detection electrodes (7) are attached. In a liquid level sensor for detecting the liquid level in a container by using an electrode (7) in which the liquid level in the container is tightened with two hexagon wrench cap bolts (2) at two upper right and lower left positions at both ends of a stopper (1) installed at the upper position and a common electrode (6) of the electrodes at the lowest position, and the pointed truss screw (3) is screwed in slightly to the side of the center of the stopper (1), a three-core VA cable (5) is sandwiched from the front and back by two stoppers (1), and two positions at the center of both ends of the stopper (1) are tightened with two hexagon wrench cap bolts (2). The pointed truss screw (3) is screwed into the center of the stopper (1) from the direction opposite to the cap bolt (back side) and contacts the middle wire of the three-core cable (5). A three-core VA cable (5) is clamped from the front and back by two pieces of fasteners (1). Two places at the center of both ends of the fastener are tightened with two hexagon wrench cap bolts (2). A pointed truss screw (3) is screwed into the center of the fastener (1) and brought into contact with the wire in the middle of the three-core cable (5). An electrode is installed at the lowest position of the three-core cable (5). Taking the electrode at the lowest position as the common electrode (6), it is connected to a position above the three-core cable on the side opposite to the side where the common electrode (6) is connected. The three-core VA cable (5) installed at the above upper position is clamped from the front and back by two pieces of fasteners. Two places at the center of both ends of the fastener (1) are tightened with two hexagon wrench cap bolts (2). Two electrodes (7) with a pointed tip at the front are screwed slightly sideways into the center of the fastener from the direction opposite to the cap bolt (the back side) and brought into contact with the left and right wires of the three-core cable (5) respectively. Since the common electrode (6) and the two electrodes (upper limit position, lower limit position) (7) at the upper position conduct electricity if immersed in the liquid and do not conduct electricity if not immersed in the liquid, this is a detection method of a floatless liquid level sensor for detecting the liquid level in the container based on the conduction between these two electrodes (7) and the common electrode (6).

Example

[0028] Figure 6 is a schematic front view of a liquid level detection sensor that installs a single three-core cable (5) in a container, attaches a common electrode (6) and two liquid level detection electrodes (7), installs a second three-core cable (5), and attaches two electrodes at the lowest and highest positions to detect the upper limit position, lower limit position, upper position, and lower position. The liquid level in the container is clamped from the front and back by the common electrode (6) of the electrodes at the lowest position and the three-core VA cable (5) with two clamps (1). The upper right and lower left positions at both ends of the clamp (1) installed at the upper position are tightened with two hexagon wrench cap bolts (2). The pointed truss screw (3) is screwed into the electrode (7) slightly to the side of the center of the clamp (1), or the three-core VA cable (5) is clamped from the front and back with two clamps (1). The two positions at the center of both ends of the clamp are tightened with two hexagon wrench cap bolts (2). In a liquid level sensor that detects using the electrode (7) with the pointed truss screw screwed into the electrode (7) slightly to the side of the center of the clamp (1) from the direction opposite to the cap bolt (the back side), The three-core VA cable (5) is clamped from the front and back with two clamps (1). The two positions at the center of both ends of the clamp (1) are tightened with two hexagon wrench cap bolts (2). The pointed truss screw is screwed into the center of the clamp, and the electrode in contact with the middle wire of the three cores is installed at the lowest position of the three-core cable. Using the electrode at the lowest position as the common electrode (6), it is connected to the position above the three-core cable (5) on the side opposite to the side where the common electrode (6) is connected. The three-core VA cable (5) is clamped from the front and back with two clamps (1). The two electrodes (7) with the upper right and lower left positions at both ends of the clamp (1) installed at the upper position tightened with two hexagon wrench cap bolts (2) are brought into contact with the left and right wires of the three-core cable respectively, or the three-core VA cable (5) is clamped from the front and back with two clamps (1). The two positions at the center of both ends of the clamp are tightened with two hexagon wrench cap bolts (2). The two electrodes with the pointed truss screw (3) screwed into the electrode (7) slightly to the side of the center of the clamp (1) from the direction opposite to the cap bolt (the back side) are brought into contact with the left and right wires of the three-core cable (5) respectively, Install yet another three-core VA cable (5) inside the container. Clamp the three-core VA cable from the front and back with two pieces of fasteners (1). Tighten two places at the center of both ends of the fastener (1) with two hex wrench cap bolts (2). Screw the pointed truss screw (3) into the center of the fastener (1) and install it at the lowest position of the three-core cable (5) with an additional electrode (8) in contact with the wire in the middle of the three-core cable. Clamp the three-core VA cable (5) from the front and back with two pieces of fasteners (1). Tighten two places at the upper right and lower left of both ends of the fastener (1) with two hex wrench cap bolts (2). Screw the pointed truss screw (3) slightly sideways into the center of the fastener (1) to install the electrode (9), or clamp the three-core VA cable (5) from the front and back with two pieces of fasteners (1). Tighten two places at the center of both ends of the fastener with two hex wrench cap bolts (2). Install the electrode (9) with the pointed truss screw screwed slightly sideways into the center of the fastener from the direction opposite to the cap bolt (the back side) at the uppermost position of the three-core cable (5), each functioning as a sensor at the lower limit position and the upper limit position. Since the common electrode (6) and the four electrodes at the upper position (upper limit position (7), lower limit position (7), upper limit position (9), lower limit position (8)) conduct electricity if immersed in the liquid and do not conduct electricity if not immersed in the liquid, this is a detection method of a floatless liquid level sensor for detecting the liquid level in the container based on the conduction between these four electrodes and the common electrode (6). As described above, when more detection positions are desired, multiple three-core cables (5) can be used to increase the electrodes to be detected.

[0029] If the above-mentioned electrodes are rounded by removing the corners, the installation work and cleaning work can be done without getting injured. Also, by removing the corners, it becomes even more difficult for dust and the like to adhere.

[0030] The above is a liquid level sensor comprising a fastener (1), a hex wrench cap bolt (2), a pointed truss screw (3), a packing (4), a three-core VA cable (5), a common electrode (6), a liquid level detection electrode (7), a lower limit position detection electrode (8), and an upper limit position detection electrode (9), but each part can be improved little by little to make it easier to use.

Industrial Applicability

[0031] As described above, the liquid level sensor according to the present invention has electrodes installed in a three-core VA cable, is light, inexpensive, easy to install, and easy to clean, and is mainly used in water supply tanks, sewage, wastewater, and drainage tanks. In addition, since it can be used for conductive liquids, it can also be used in industries such as the chemical industry and the food industry.

Explanation of Reference Numerals

[0032] 1 Stopper 2 Hexagon wrench cap bolt 3 Pointed truss screw 4 Packing 5 Three-core VA cable 6 Common electrode 7 Liquid level detection electrode 8 Lower limit position detection electrode 9 Upper limit position detection electrode

Claims

1. In the electrode of a liquid level sensor composed of a metal stopper, a hexagon wrench cap bolt for tightening at both ends of the stopper, a pointed truss screw, and a packing, two pieces of the metal stopper sandwich a three-core VA cable from the front and back, and two places at the center of both ends of the stopper are tightened with two hexagon wrench cap bolts. The pointed truss screw is screwed into the center of the stopper and brought into contact with the single copper wire in the middle of the three-core cable to serve as an electrode. A packing is attached to the truss screw to prevent liquid from entering between the stopper and the electrode. It can be installed at the lowest position of the three-core cable to be used as a common electrode or as the lowest electrode at the end of another three-core cable. The wire end of the three-core cable with this electrode is sealed with silicone caulking to prevent contact with the liquid. The electrode of the floatless liquid level sensor is characterized by this.

2. In the electrode of a liquid level sensor composed of a metal stopper, a hexagon wrench cap bolt for tightening at both ends of the stopper, a pointed truss screw, and a packing, two pieces of the metal stopper sandwich a three-core VA cable from the front and back, and two places at the upper right and lower left of both ends of the stopper are tightened with two hexagon wrench cap bolts. The pointed truss screw is screwed slightly sideways into the center of the stopper and brought into contact with either the left or right single copper wire of the three-core cable to serve as an electrode. When the left and right of this electrode are reversed, it can come into contact with the wire of the other three-core cable. A packing is attached to the truss screw to prevent liquid from entering between the stopper and the electrode. This electrode is installed at a position above the three-core cable and is characterized by detecting the liquid level. The electrode of the floatless liquid level sensor is characterized by this.

3. In the electrode of a liquid level sensor composed of a metal stopper, a cap bolt for a hexagonal wrench that tightens at both ends of the stopper, a pointed truss screw, and a packing, two pieces of metal stoppers sandwich a three-core VA cable from the front and back, and two places at the center of both ends of the stopper are tightened with two cap bolts for a hexagonal wrench. A pointed truss screw is screwed in slightly to the side of the center of the stopper from the direction opposite to the cap bolt (the back side) and brought into contact with either the left or right single copper wire of the three-core cable to form an electrode. If the left and right of the electrode are reversed, it can contact the wire of the other three-core cable. A packing is attached to the truss screw to prevent liquid from entering between the stopper and the electrode. This electrode is installed at a position above the three-core cable to detect the liquid level, and it is a characteristic electrode of a floatless liquid level sensor.

4. In a liquid level sensor that detects the liquid level in a container using the electrode according to claim 1 and the electrode according to claim 2 or claim 3, two pieces of stoppers sandwich a three-core VA cable from the front and back, two places at the center of both ends of the stopper are tightened with two cap bolts for a hexagonal wrench, a pointed truss screw is screwed into the center of the stopper, and an electrode that contacts the single copper wire in the middle of the three-core cable is installed at the lowest position of the three-core cable. Taking the electrode at the lowest position as a common electrode, it is connected to a position above the three-core cable on the side opposite to the side where the common electrode is connected. The two electrodes according to claim 2 are brought into contact with the left and right wires of the three-core cable respectively, or the two electrodes according to claim 3 are brought into contact with the left and right wires of the three-core cable respectively. If the common electrode and the two electrodes at the upper position (upper limit position, lower limit position) are immersed in the liquid, they conduct electricity, and if they are not immersed in the liquid, they do not conduct electricity. Therefore, based on the conduction between these two electrodes and the common electrode, a method for detecting the liquid level in a container using a floatless liquid level sensor is provided.

5. In a liquid level sensor for detecting the liquid level in a container using the electrodes described in claim 1 and the electrodes described in claim 2 or claim 3, a three-core VA cable is clamped from the front and back with two clips, and two points at the center of both ends of the clip are tightened with two hexagon wrench cap bolts. A pointed truss screw is screwed into the center of the clip and brought into contact with the single copper wire in the middle of the three-core cable. The electrode thus formed is installed at the lowest position of the three-core cable. Using the electrode at the lowest position as a common electrode, it is connected to a position above the three-core cable on the side opposite to the side to which the common electrode is connected. The two electrodes described in claim 2 are brought into contact with the left and right wires of the three-core cable respectively, or the two electrodes described in claim 3 are brought into contact with the left and right wires of the three-core cable respectively. Still another three-core VA cable is installed in the container. The electrode described in claim 1 is installed at the lowest position of the three-core cable, and one electrode described in claim 2 or claim 3 is installed at the uppermost position of the three-core cable, so that they function as sensors for the lower limit position and the upper limit position respectively. Since the common electrode and the four electrodes at the upper positions (upper limit position, lower limit position, upper limit boundary position, lower limit boundary position) conduct electricity when immersed in the liquid and do not conduct electricity when not immersed in the liquid, a method for detecting the liquid level in the container based on the conduction between these four electrodes and the common electrode in a floatless liquid level sensor.

Images