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 uses 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 detects the flow of current between electrodes when a conductive liquid touches between the electrodes and outputs a detection signal based on this. The capacitance type detects and measures the difference between the dielectric constant of the liquid and that of air, and outputs detection and measurement signals. It cannot be measured when the dielectric constant of the liquid changes significantly.

[0003] 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 up and down floating amount of the float. An invention has been made in which a permanent magnet is provided inside the float, and a reed switch or the like is turned on and off by the change in magnetic flux due to 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 likely to break due to repeated bending.

[0005] 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 contact 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 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 table leaving both ends (Patent Document 2). Electrode rods are typically heavy, 6mm diameter stainless steel rods, making installation and cleaning difficult. Furthermore, contact between electrode rods can cause malfunctions. Even with separators to keep the electrodes apart, debris on the separators can lead to malfunctions. This limits the range of use, for example, requiring the use of only clean tap water.

[0006] Prior art has been invented, a water level gauge (Patent Document 3) that measures the water level in a container based on the resistance value between each of the multiple electrode parts and the common electrode. This common electrode is connected to the cable on the opposite side from where it is connected to the common electrode. In this embodiment, five electric wires are bundled together in an inorganic insulated cable. Each electrode part at a measurement point is submerged in water, creating electrical contact with the common electrode via water. In this case, the arrangement and wiring of the electrodes used to measure each water level are complex, making it difficult to easily change the position of the measuring electrodes or bend them.

[0007] Furthermore, an electrode-type liquid level gauge has been invented in which an insulating material is packed between an outer cylinder (synthetic resin) and an inner cylinder (synthetic resin) of a protective tube, and multiple divided electrode pieces are arranged in the insulating material with gaps in the longitudinal direction, and a small screw with a head is inserted from the outside of the protective tube so as to be removable and into contact with the electrode pieces, and when the small screw is removed, liquid enters the small hole and comes into contact with the electrode pieces, and conductivity is established (Patent Document 4). First, multiple electrode pieces are arranged within the insulating material of the protective tube, with gaps between them along their length. Then, screw holes are provided in the gaps between the electrode pieces, into which small screws with heads are screwed from the outside of the protective tube. Contact between the liquid and the electrodes occurs through the small screw holes through which the electrode pieces are inserted. Firstly, it is difficult to arrange multiple electrode pieces within the insulating material (rubber or synthetic resin) of the protective tube with gaps along its length to prevent contact with each other. Secondly, since the small screws are in contact with the electrode pieces, conductive metals such as iron cannot be used for the screws. Thirdly, these small holes may become clogged with debris, potentially causing problems where the electrode pieces do not come into contact with the liquid. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 02-257020 [Patent Document 2] Japanese Patent Publication No. 11-023346 [Patent Document 3] Japanese Patent Publication No. 2018-146325 [Patent Document 4] Publicly available Practical Application No. 02-59436 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] There are float-type liquid level gauges that determine the liquid level by detecting the amount of vertical movement of a float that floats on the liquid surface. Inventions have been made that incorporate a permanent magnet inside the float, allowing a reed switch or similar device to be activated or deactivated by the change in magnetic flux caused by the float's movement. Float-type float traps are commonly used in sewage manholes, but they frequently suffer from problems such as debris accumulation, poor buoyancy due to broken floats, and broken wires. If debris accumulates on the surface of the float, it may stop floating. If the float is damaged, liquid can enter and it will stop floating. The float may get caught on the pump or footrest (step) inside the tank and stop moving up and down. Also, if the movable part of the float is wired, it is prone to breaking due to repeated bending. Electrode-type liquid level gauges detect the height of the liquid level by electrical conductivity through the liquid between multiple electrode rods. These electrode-type liquid level gauges use an electrode holder to mount multiple electrode rods of different lengths. They utilize the fact that the lower ends of the electrode rods of different lengths come into contact with or separate from the liquid surface as the liquid level rises or falls, and detect the liquid level position through electrical conductivity caused by liquid junctions between the electrode rods in contact with the liquid surface. An electrode-type liquid level gauge has been invented that uses electrode rods of different lengths, with their surfaces covered with insulating tape, leaving both ends exposed. Electrode rods are typically heavy, 6mm diameter stainless steel rods, making installation and cleaning difficult. Furthermore, contact between electrode rods can cause malfunctions. Even with separators to keep the electrodes apart, debris on the separators can lead to malfunctions. This limits the range of use, for example, requiring the use of only clean tap water.

[0010] A water level gauge has been invented that measures the water level in a container based on the resistance value between each of the multiple electrodes and the common electrode. This common electrode is connected to the cable on the opposite side from where the electrodes are connected. In this embodiment, five wires are bundled together in an inorganic insulated cable. Each electrode at a measurement point becomes electrically connected to the common electrode via water when submerged in water. In this case, the arrangement and wiring of the electrodes used to measure each water level are complex, making it difficult to easily change the position of the measuring electrodes or bend them. A liquid level sensor is needed that is easy to install, allows for easy repositioning of the liquid level detection electrode, is resistant to damage, and is flexible.

[0011] Furthermore, an electrode-type liquid level gauge has been invented in which an insulating material is packed between an outer cylinder (synthetic resin) and an inner cylinder (synthetic resin) of a protective cylinder, and multiple divided electrode pieces are arranged in the insulating material with gaps in the longitudinal direction. Small screws with heads are inserted from the outside of the protective cylinder so as to be removable and make contact with the electrode pieces, and when the small screws are removed, liquid enters the small holes and makes contact with the electrode pieces, thus creating conductivity. Multiple electrode pieces are arranged within the insulating material of the protective tube, with gaps between them along their length. Screw holes are provided in the gaps between the electrode pieces, into which small screws with heads are screwed from the outside of the protective tube. Contact between the liquid and the electrodes occurs through the small screw holes through which the electrode pieces are inserted. First, it is difficult to arrange multiple electrode pieces within the insulating material (rubber or synthetic resin) of the protective tube, leaving gaps along its length so that they do not come into contact with each other. Also, since the small screws are in contact with the electrode pieces, conductive metals such as iron cannot be used for the screws. Furthermore, these small holes may become clogged with debris, potentially causing problems where the electrode pieces do not come into contact with the liquid. There is a need for liquid level sensors for sewage, wastewater, drainage, and drinking water that are simple to use, easy to install, and free from problems caused by debris, limescale, and floating objects. [Means for solving the problem]

[0012] The electrode of this liquid level sensor consists of a metal fastener, hexagonal cap bolts that are tightened at both ends of the fastener, a pointed truss screw, and a packing. The three-core VA cable is sandwiched between two pieces of the metal fastener from the front and back, and the two central points of both ends of the fastener are tightened with two hexagonal cap bolts. The pointed truss screw is screwed into the center of the fastener and contacts the single copper wire in the middle of the three-core cable to form the 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 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 the electrode attached is sealed with silicone sealant to prevent contact between the liquid and the wire. A three-core VA cable is a flat cable made by covering single copper wires (not twisted wires) with vinyl resin, then arranging three more covered copper wires side by side and covering them with vinyl resin again. This three-core cable is a general-purpose product, readily available in most stores, and inexpensive. While it is usually coated with polyvinyl chloride resin, it can also be coated with Teflon® resin or other materials to increase chemical resistance. The metal fasteners, the hexagonal wrench cap bolts used to tighten them at both ends, and the pointed truss screws were made of corrosion-resistant stainless steel, SUS316. These parts could also be made of SUS304, and if greater corrosion resistance is required, titanium, Hastelloy (HASB, HASC) (a trademark of Haynes Corporation, USA), etc., can be used. Two gaskets made of paper or similar material, with a thickness of 0.5 mm, were used. The three-core VA cable is sandwiched between two metal fasteners from the front and back. Two hexagonal cap bolts are used to apply pressure to the center of both ends of the fasteners, tightening them so much that the cable deforms. A pointed truss screw is then screwed into the center of the fastener with a Phillips screwdriver, making contact with the middle wire of the three-core cable. A gasket is attached to the truss screw to prevent liquid from entering between it and the fastener, and the electrode is attached to the three-core cable. This is because if liquid enters the wire via the truss screw, it will rise through the gap by capillary action, corroding the wire and causing a short circuit with other wires to which electrodes are attached within the three-core cable. Over time, this can reach the control panel and cause malfunctions, so this method prevents liquid from entering the wires of the three-core VA cable.

[0013] In this electrode for a liquid level sensor, which consists of a metal fastener, hexagonal cap bolts tightened at both ends of the fastener, a pointed truss screw, and a packing, the three-core VA cable is sandwiched between two pieces of the metal fastener from the front and back, and the two hexagonal cap bolts tightened at the upper right and lower left ends of the fastener, and the pointed truss screw is screwed slightly to the side of the center of the fastener, making contact with one of the single copper wires on either the left or right side of the three-core cable to form an electrode, and by reversing the left and right sides of the electrode, it can make contact with the other wire of the three-core cable, and a packing is attached to the truss screw to prevent liquid from entering between it and the fastener, this electrode is an electrode for a floatless liquid level sensor that is installed above the three-core cable to detect the liquid level. The fastener is secured at two points, the upper right and lower left, with two hexagonal cap bolts. A pointed truss screw is screwed slightly to the side of the center of the fastener, making contact with one of the left or right wires of the three-core cable to act as an electrode. The bolt holes are positioned close together at the upper right and lower left ends of the fastener to prevent the bolt heads and truss screw heads from overlapping, thus reducing the size of the fastener. Of course, bolt holes could also be drilled at the upper left and lower right ends of the fastener. Larger electrodes tend to attract debris and cause malfunctions, but reducing the size of the electrodes prevents debris from accumulating.

[0014] In this liquid level sensor electrode, which consists of a metal fastener, hexagonal wrench cap bolts tightened at both ends of the fastener, a pointed truss screw, and a packing, the three-core VA cable is sandwiched between two pieces of the metal fastener from the front and back, and the two central points at both ends of the fastener are tightened with two hexagonal wrench cap bolts. The pointed truss screw is screwed in from the opposite side (back side) of the cap bolts, slightly to the side of the center of the fastener, and contacts one of the single copper wires on either the left or right side of the three-core cable to form an electrode. By reversing the left and right sides of the electrode, it can contact the other wire of the three-core cable. A packing is attached to the truss screw to prevent liquid from entering between it and the fastener. This electrode is installed above the three-core cable to detect the liquid level in a floatless liquid level sensor. A pointed truss screw was screwed into the fastener from the opposite side (back) of the cap bolt, slightly to the side of the center, and made contact with one of the left or right wires of the three-core cable to form an electrode. By screwing the truss screw from the opposite side (back) of the cap bolt, the heads of the cap bolt and the truss screw did not overlap, allowing the electrode dimensions to be reduced. As a result, dust did not accumulate on the electrode.

[0015] In a liquid level sensor that detects the liquid level inside a container using an electrode where the common electrode is located at the lowest position and two hexagonal cap bolts are tightened at the upper right and lower left ends of a fastener installed at a higher position, and a pointed truss screw is screwed slightly to the side of the center of the fastener, or an electrode where two hexagonal cap bolts are tightened at the center of both ends of the fastener, and a pointed truss screw is screwed slightly to the side of the center of the fastener from the opposite side (back side) of the cap bolts, A three-core VA cable is sandwiched from the front and back by two fasteners, and two hexagonal cap bolts are tightened at two points in the center of both ends of the fasteners, and a pointed truss screw is screwed into the center of the fastener, and an electrode that is in contact with the middle wire of the three-core cable is placed at the lowest position of the three-core cable, and the electrode at the lowest position is used as the common electrode, and two electrodes are connected to the upper position of the cable on the opposite side from where the common electrode is connected, and the three-core VA cable is sandwiched from the front and back by the two metal fasteners mentioned above, and two hexagonal cap bolts are tightened at two points in the upper right and lower left of both ends of the fastener, and a pointed truss screw is screwed slightly to the side of the center of the fastener, and two electrodes are placed at the upper position, and two hexagonal cap bolts are tightened at two points in the upper right and lower left of both ends of the fastener, and two electrodes that are screwed slightly to the side of the center of the fastener This floatless liquid level sensor detection method involves contacting the left and right wires of a three-core cable with two electrodes, or sandwiching the three-core VA cable from the front and back with two metal fasteners, tightening two hexagonal cap bolts at the center of both ends of the fasteners, and screwing two pointed truss screws slightly to the side of the center of the fastener from the opposite side (back) of the cap bolts to contact the left and right wires of the three-core cable, respectively. Since there is conductivity if the common electrode and the two electrodes at the upper position (upper limit position and lower limit position) are immersed in the liquid, and no conductivity if they are not immersed in the liquid, the liquid level in the container is detected based on the conductivity between these two electrodes and the common electrode.

[0016] In a liquid level sensor that detects the liquid level inside a container using an electrode where the common electrode is located at the lowest position and two hexagonal cap bolts are tightened at the upper right and lower left ends of a fastener installed at a higher position, and a pointed truss screw is screwed slightly to the side of the center of the fastener, or an electrode where two hexagonal cap bolts are tightened at the center of both ends of the fastener, and a pointed truss screw is screwed slightly to the side of the center of the fastener from the opposite side (back side) of the cap bolts, The three-core VA cable is sandwiched from the front and back by two fasteners, and the two central points at both ends of the fasteners are tightened with two hexagonal cap bolts, and a pointed truss screw is screwed into the center of the fastener, and the electrode that is in contact with the middle wire of the three cores is placed at the lowest position of the three-core cable, and the electrode at the lowest position is used as the common electrode, and is connected to the upper position of the three-core cable on the opposite side from where the common electrode is connected, and the three-core VA cable is sandwiched from the front and back by the two metal fasteners mentioned above, and the upper right of both ends of the fasteners is placed at the upper position, Tighten the two points on the lower left with two hexagonal cap bolts, and screw in two pointed truss screws slightly to the side of the center of the fastener, making contact with the left and right wires of the three-core cable, respectively. Alternatively, sandwich the three-core VA cable from the front and back with the two pieces of the metal fastener mentioned above, tighten the two points on the center of both ends of the fastener with two hexagonal cap bolts, and screw in two pointed truss screws slightly to the side of the center of the fastener from the opposite side of the cap bolts (back side), making contact with the left and right wires of the three-core cable, respectively. Install yet another three-core VA cable inside the container. Clamp the three-core VA cable from the front and back with two pieces of fasteners. Tighten two hex wrench cap bolts at two central positions at both ends of the fastener. Screw a pointed truss screw into the central part of the fastener and make it contact the electrode on the middle wire of the three-core cable, and install the electrode 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 fastener. Screw a pointed truss screw slightly sideways into the central part of the fastener, or tighten two hex wrench cap bolts at two central positions at both ends of the above fastener, and screw a pointed truss screw slightly sideways into the central part of the fastener from the direction (back side) opposite to the cap bolt, and install the electrodes at positions above the three-core cable, which 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, 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, multiple three-core cables can be used and the number of electrodes to be detected can be increased.

[0017] When changing the position of the electrode to be detected, loosen 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. Fill the hole of the truss screw at the previous position with silicone caulking. Alternatively, the fastener 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 the control panel.

[0019] This liquid level sensor can be used with conductive liquids. It is primarily used in tanks for sewage, wastewater, drainage, and water supply. Because it can be used with conductive liquids, it can also be used in industries such as the chemical and food industries. [Effects of the Invention]

[0020] This liquid level sensor is easy to install. Electrodes are attached to a three-core VA cable by clamping them from the front and back using a hex wrench and Phillips screwdriver, eliminating the need for a power supply and permits for using open flames during installation. Electrode positions are determined by the distance from the bottom of the tank; a common electrode is installed at the lowest position, followed by electrodes in sequential positions upwards. While electrodes can be attached to the three-core cable on-site, its light weight and portability allow for pre-attachment of the electrodes, with the cable then extended and attached at the site. It can be used with small-capacity tanks and can be installed on the inner wall of the tank. When using multiple three-core cables, they can be secured with cable ties. Even tanks with sloping ceilings can be installed vertically by bending the three-core cable at the mounting point. During cleaning, the three-core cable can be pulled up from the tank, cleaned, and the electrodes inspected. Because the electrodes are made to a minimum size, very little dust or debris accumulates on them. As described above, the electrodes of this liquid level sensor are mainly used in water tanks, sewage tanks, wastewater tanks, and drainage tanks. Since it can be used with conductive liquids, it can also be used in industries such as the chemical and food industries. Installation is simple, and cleaning is also easy. [Brief explanation of the drawing]

[0021] [Figure 1] This is an exploded view of an electrode that can be installed at the bottom of a three-core cable and used as a common electrode, or as the bottom electrode at the end of another three-core cable. [Figure 2] This is an exploded view of an electrode used as a liquid level detection electrode, installed above a three-core cable. [Figure 3] This is an exploded view of another electrode, which is installed above the three-core cable and used as a liquid level detection electrode. [Figure 4]This is a schematic front view of a liquid level detection sensor, in which a single three-core cable is installed inside a container, and a common electrode and two liquid level detection electrodes are attached. [Figure 5] This is a schematic front view of a liquid level detection sensor, in which a single three-core cable is installed inside a container, and a common electrode and two other electrodes for liquid level detection are attached. [Figure 6] This is a schematic front view of a liquid level detection sensor that uses a single three-core cable installed inside a container, with a common electrode and two liquid level detection electrodes attached. A second three-core cable is then installed, with two electrodes attached to the lowest and highest points, to detect the upper limit position, lower limit position, and both the upper and lower limit positions. [Modes 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] Figure 1 shows an exploded view of an electrode that can be installed at the bottom of a three-core cable (5) and used as a common electrode, or as the bottom electrode at the end of another three-core cable. The electrode of the liquid level sensor consists of a metal fastener (1), hexagonal wrench cap bolts (2) tightened at both ends of the fastener (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 fastener (1), and the two hexagonal wrench cap bolts (2) are tightened at two points in the center of both ends of the fastener (1). The pointed truss screw (3) is screwed into the center of the fastener (1) and contacts 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 it and the fastener (1). It can be installed at the lowest position of the three-core cable (5) 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 (5) with the electrode attached is sealed with silicone sealant to prevent contact with liquid. The three-core VA cable uses a flat three-core cable in which three single copper wires are coated with polyvinyl chloride resin, and these three wires are further coated with polyvinyl chloride resin. It is a readily available and inexpensive general-purpose product. The metal fasteners, the hexagonal wrench-operated cap bolts used to tighten them at both ends, and the pointed truss screws were made of corrosion-resistant stainless steel, SUS316. For the packing, commercially available sheet packing was cut into circles and used. Two pieces, each 0.5 mm thick, were used. [Examples]

[0024] Figure 2 is an exploded view of the electrode, which is installed above the three-core cable (5) and used as a liquid level detection electrode. In this electrode for a liquid level sensor, which consists of a metal fastener (1), hexagonal wrench cap bolts (2) tightened at both ends of the fastener (1), a pointed truss screw (3), and a packing (4), the three-core VA cable (5) is sandwiched between two pieces of the metal fastener (1) from the front and back, and the two hexagonal wrench cap bolts (2) are tightened at the upper right and lower left ends of both ends of the fastener (1). The pointed truss screw (3) is screwed slightly to the side of the center of the fastener (1) and contacts one of the single copper wires on either the left or right side of the three-core cable (5) to form an electrode. By reversing the left and right sides of the electrode, it can contact the other wire of the three-core cable (5). A packing (4) is attached to the truss screw (3) to prevent liquid from entering between it and the fastener (1). This electrode is installed above the three-core cable (5) to detect the liquid level and is an electrode for a floatless liquid level sensor. The bolt (2) holes are positioned at two locations, the upper right and lower left, on both ends of the fastener (1), so that the heads of the bolts (2) and the truss screws (3) do not overlap, thus reducing the size of the fastener (1). If the electrodes are large, debris can easily get caught and cause malfunctions, but by making the electrodes smaller, debris no longer adheres to them. [Examples]

[0025] Figure 3 is an exploded view of another electrode, which is installed above the three-core cable (5) and used as a liquid level sensing electrode. In this electrode for a liquid level sensor, which consists of a metal fastener (1), hexagonal wrench cap bolts (2) tightened at both ends of the fastener (1), a pointed truss screw (3), and a packing (4), the three-core VA cable (5) is sandwiched between two pieces of the metal fastener (1) from the front and back, and the two central points at both ends of the fastener (1) are tightened with two hexagonal wrench cap bolts (2). The pointed truss screw (3) is screwed in from the opposite side (back) of the cap bolts, slightly to the side of the center of the fastener, and contacts one of the single copper wires on either the left or right side of the three-core cable to form an electrode. By reversing the left and right sides of the electrode, it can contact the other wire of the three-core cable (5). A packing (4) is attached to the truss screw (3) to prevent liquid from entering between it and the fastener (1). This electrode is installed above the three-core cable (5) to detect the liquid level and is an electrode for a floatless liquid level sensor. A pointed truss screw (3) was screwed into the fastener (1) slightly to the side of the center from the opposite side of the cap bolt (back side), and contacted with one of the left or right wires of the three-core cable (5) to form an electrode. By screwing the truss screw (3) from the opposite side of the cap bolt (back side), the head of the cap bolt (2) and the head of the truss screw (3) did not overlap, allowing the electrode dimensions to be reduced. As a result, dust did not accumulate on the electrode. [Examples]

[0026] Figure 4 is a schematic front view of a liquid level detection sensor in which a single three-core cable (5) is installed inside a container, and a common electrode (6) and two liquid level detection electrodes (7) are attached. In a liquid level sensor that detects the liquid level in a container using an electrode (7) with a common electrode (6) at the lowest position and two hexagonal cap bolts (2) at the upper right and lower left ends of a fastener (1) installed at a higher position, and a pointed truss screw (3) screwed slightly to the side of the center of the fastener (1), a three-core VA cable (5) is sandwiched from the front and back by two fasteners (1), two hexagonal cap bolts (2) at the center of both ends of the fastener (1), a pointed truss screw (3) is screwed into the center of the fastener (1), and an electrode that contacts the middle wire of the three-core cable (5) is installed at the lowest position of the three-core cable (5), and the lowest This is a detection method for a floatless liquid level sensor that uses the electrode at the upper position as a common electrode (6), connects to an upper position on the three-core cable (5) on the opposite side from where the common electrode (6) is connected, and fastens two electrodes (7) at the upper right and lower left ends of a fastener (1) installed at the upper position with two hexagonal wrench cap bolts (2), respectively, to contact the left and right wires of the three-core cable (5). Since there is conductivity if the common electrode (6) and the two electrodes at the upper position (upper limit position and lower limit position) are immersed in liquid, and no conductivity if they are not immersed in liquid, the liquid level in the container is detected based on the conductivity between these two electrodes (7) and the common electrode (6). [Examples]

[0027] Figure 5 is a schematic front view of a liquid level detection sensor in which a single three-core cable (5) is installed inside a container, and a common electrode (6) and two other liquid level detection electrodes (7) are attached. In a liquid level sensor that detects the liquid level inside a container using an electrode (7) with a common electrode (6) at the lowest position and a three-core VA cable (5) installed at a higher position, sandwiched from the front and back by two fasteners (1), with two hexagonal wrench cap bolts (2) tightened at two points in the center of both ends of the fasteners, and a pointed truss screw (3) screwed slightly to the side of the center of the fastener from the opposite side (back side) of the cap bolts, The three-core VA cable (5) is sandwiched from the front and back by two fasteners (1), and the two central points at both ends of the fasteners are tightened with two hexagonal wrench cap bolts (2), and a pointed truss screw (3) is screwed into the center of the fastener (1), and the electrode that is in contact with the middle wire of the three-core cable (5) is placed at the lowest position of the three-core cable (5), and the electrode at the lowest position is designated as the common electrode (6), and the three-core VA cable (5) placed at the upper position is connected to the above-mentioned side of the three-core cable at an upper position, and the three-core VA cable (5) is sandwiched from the front and back by two fasteners, and the fasteners (1) This floatless liquid level sensor detection method involves tightening two hexagonal cap bolts (2) at two points in the center of both ends of the fastener, and screwing two pointed truss screws (3) from the opposite side (back side) of the cap bolts into the left and right wires of the three-core cable (5), respectively, so that the common electrode (6) and the two upper electrodes (upper limit position, lower limit position) (7) conduct electricity if they are immersed in the liquid, and do not conduct electricity if they are not immersed in the liquid, thereby detecting the liquid level in the container based on the conductivity between these two electrodes (7) and the common electrode (6). [Examples]

[0028] Figure 6 is a schematic front view of a liquid level detection sensor that detects the upper limit position, lower limit position, and upper and lower limit positions by installing one three-core cable (5) inside a container, attaching a common electrode (6) and two liquid level detection electrodes (7), and then installing a second three-core cable (5) with two electrodes attached to the lowest and highest points. In a liquid level sensor that detects the liquid level inside a container, the common electrode (6) of the lowest electrode and the three-core VA cable (5) are sandwiched from the front and back by two fasteners (1), and the two upper right and lower left corners of the fastener (1) installed at the upper position are tightened with two hexagonal wrench cap bolts (2), and a pointed truss screw (3) is screwed slightly to the side of the center of the fastener (1) to the electrode (7), or the three-core VA cable (5) is sandwiched from the front and back by two fasteners (1), and the two central corners of the fasteners are tightened with two hexagonal wrench cap bolts (2), and a pointed truss screw (3) is screwed slightly to the side of the center of the fastener (1) from the opposite side (back side) of the cap bolts to the electrode (7), The three-core VA cable (5) is sandwiched from the front and back by two fasteners (1), and the two central points at both ends of the fasteners (1) are tightened with two hexagonal wrench cap bolts (2), and a pointed truss screw is screwed into the center of the fastener, and the electrode that is in contact with the middle wire of the three cores is set at the lowest position of the three-core cable, and the electrode at the lowest position is set as the common electrode (6), and the common electrode (6) is connected to the upper position of the three-core cable (5) on the opposite side from which it is connected, and the three-core VA cable (5) is sandwiched from the front and back by two fasteners (1), and at the upper position Two electrodes (7) are attached to the left and right wires of the three-core cable, respectively, by tightening two hexagonal wrench cap bolts (2) at the upper right and lower left corners of both ends of the installed fastener (1). Alternatively, the three-core VA cable (5) is sandwiched from the front and back by two fasteners (1), and two hexagonal wrench cap bolts (2) are tightened at the two central points of both ends of the fastener. Two electrodes are then screwed in from the opposite side (back) of the cap bolts, slightly to the side of the center of the fastener (1), and these electrodes are attached to the left and right wires of the three-core cable (5). Furthermore, another three-core VA cable (5) is placed inside the container, the three-core VA cable is sandwiched from the front and back with two fasteners (1), the two central points at both ends of the fasteners (1) are tightened with two hexagonal wrench cap bolts (2), a pointed truss screw (3) is screwed into the center of the fastener (1), an electrode (8) that is in contact with the middle wire of the three-core cable is placed at the bottom of the additional three-core cable (5), the three-core VA cable (5) is sandwiched from the front and back with two fasteners (1), and the two upper right and lower left points at both ends of the fasteners (1) are tightened with hexagonal wrench caps Two bolts (2) are used to fasten the electrode (9) with a pointed truss screw (3) screwed slightly to the side of the center of the fastener (1), or the three-core VA cable (5) is sandwiched from the front and back by two fasteners (1), and the two central points at both ends of the fastener are fastened with two hexagonal wrench cap bolts (2). An electrode (9) with a pointed truss screw screwed slightly to the side of the center of the fastener is installed at the top of the three-core cable (5) from the opposite side (back side) of the cap bolts, and these functions as sensors for the lower limit position and upper limit position, respectively. This is a detection method for a floatless liquid level sensor that detects the liquid level in a container based on the conductivity between the common electrode (6) and the four electrodes at the upper positions (upper limit position (7), lower limit position (7), upper limit limit position (9), and lower limit limit position (8)), which conduct electricity if the common electrode (6) and the four electrodes at the upper positions (upper limit position (7), lower limit position (7), upper limit limit position (9), and lower limit limit position (8)). As mentioned above, if you want to increase the number of detection locations, you can use multiple three-core cables (5) to increase the number of electrodes to be detected.

[0029] By removing the corners and rounding the edges of the electrodes mentioned above, installation and cleaning can be performed without causing injury. Furthermore, rounding the corners makes it even more difficult for dirt and debris to adhere to them.

[0030] The liquid level sensor described above includes a fastener (1), a cap bolt for a hex wrench (2), a pointed truss screw (3), a packing (4), a three-core VA cable (5), a common electrode (6), an electrode for detecting the liquid level (7), an electrode for detecting the lower limit position (8), and an electrode for detecting the upper limit position (9). However, each part can be slightly improved to make it easier to use. [Industrial applicability]

[0031] As described above, the liquid level sensor according to this invention has electrodes attached to a three-core VA cable, making it lightweight, inexpensive, easy to install, and easy to clean. It is mainly used in water tanks, sewage tanks, wastewater tanks, and drainage tanks. It can also be used with conductive liquids, so it can be used in industries such as the chemical industry and the food industry. [Explanation of symbols]

[0032] 1. Fastener 2. Hex wrench cap bolts 3. Pointed truss screws 4. Packing 5 Three-core VA cable 6 Common electrode 7. Electrode for liquid level detection 8. Electrode for detecting the lower limit position 9. Electrode for detecting upper limit position

Claims

1. An electrode for a liquid level sensor, comprising a metal fastener, hexagonal cap bolts tightened at both ends of the fastener, a pointed truss screw, and a packing, characterized in that a three-core VA cable is sandwiched from the front and back by two pieces of the metal fastener, two hexagonal cap bolts tightened at two points in the center of both ends of the fastener, a pointed truss screw is screwed into the center of the fastener and contacts the single copper wire in the middle of the three-core cable to form 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 as a common electrode, or as the lowest electrode at the end of another three-core cable, and the wire end of the three-core cable to which the electrode is attached is sealed with silicone sealant to prevent contact with liquid.

2. An electrode for a liquid level sensor, comprising a metal fastener, hexagonal cap bolts tightened at both ends of the fastener, a pointed truss screw, and a packing, wherein the three-core VA cable is sandwiched between two pieces of the metal fastener from the front and back, two hexagonal cap bolts tightened at two points on the upper right and lower left ends of the fastener, a pointed truss screw is screwed slightly to the side of the center of the fastener, and contacts one of the single copper wires on either the left or right side of the three-core cable to form an electrode, and by reversing the left and right sides of the electrode, it can contact the other wire of the three-core cable, and a packing is attached to the truss screw to prevent liquid from entering between it and the fastener, and this electrode is installed above the three-core cable to detect the liquid level.

3. An electrode for a liquid level sensor, comprising a metal fastener, hexagonal cap bolts tightened at both ends of the fastener, a pointed truss screw, and a packing, wherein the three-core VA cable is sandwiched between two pieces of the metal fastener from the front and back, two hexagonal cap bolts tightened at two points in the center of both ends of the fastener, and a pointed truss screw is screwed in slightly to the side of the center of the fastener from the opposite side (back side) of the cap bolts, making contact with one of the single copper wires on the left or right of the three-core cable to form an electrode, and by reversing the left and right sides of the electrode, it can be made to contact the other wire of the three-core cable, and a packing is attached to the truss screw to prevent liquid from entering between it and the fastener, and this electrode is installed above the three-core cable to detect the liquid level.

4. A liquid level sensor for detecting the liquid level in a container using the electrode described in claim 1 and the electrode described in claim 2 or claim 3, wherein a three-core VA cable is sandwiched from the front and back by two fasteners, two hexagonal wrench cap bolts are tightened at two points in the center of both ends of the fasteners, a pointed truss screw is screwed into the center of the fastener, an electrode that contacts the middle single copper wire of the three-core cable is installed at the lowest position of the three-core cable, the electrode at the lowest position is used as a common electrode, and two electrodes described in claim 2 are connected to the upper position of the three-core cable on the opposite side from where the common electrode is connected, and the two electrodes described in claim 3 are connected to the left and right wires of the three-core cable, respectively. A detection method for a floatless liquid level sensor, in which the common electrode and two electrodes at an upper position (upper limit position and lower limit position) conduct electricity when immersed in liquid, and do not conduct electricity when not immersed in liquid, thereby detecting the liquid level in a container based on the conductivity between these two electrodes and the common electrode.

5. A liquid level sensor for detecting the liquid level in a container using the electrode described in claim 1 and the electrode described in claim 2 or claim 3, wherein a three-core VA cable is sandwiched from the front and back by two fasteners, two hexagonal wrench cap bolts are tightened at two points in the center of both ends of the fasteners, a pointed truss screw is screwed into the center of the fastener, an electrode that contacts the middle single copper wire of the three-core cable is installed at the lowest position of the three-core cable, the electrode at the lowest position is used as a common electrode, and two electrodes described in claim 2 are connected to the upper position of the three-core cable on the opposite side from where the common electrode is connected, and the two electrodes described in claim 3 are connected to the left and right wires of the three-core cable, respectively. Furthermore, another three-core VA cable is installed inside the container, the electrode described in claim 1 is installed at the lowest point 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. A detection method for a floatless liquid level sensor, in which the common electrode and four electrodes positioned above (upper limit position, lower limit position, upper limit limit position, lower limit limit position) conduct electricity when immersed in liquid, and do not conduct electricity when not immersed in liquid, thereby detecting the liquid level in a container based on the conductivity between these four electrodes and the common electrode.

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