JPH02181642A - Electrostatic capacity sensor - Google Patents

Abstract

PURPOSE:To simplify a structure and to obtain advantage to industrial manufacture, and to realize an easy measurement, less contamination, and easy cleaning by constituting an electrode by winding a couple of linear conductors around the periphery of an insulating solid body in parallel without making them cross each other. CONSTITUTION:Any insulating material except a material which is dissolved or softened with liquid to be measured is usable as the insulating solid body 1, which is shaped in a columnar, conic, rectangular, prismatic, pyramid, or flat plate shape or combining several insulators. The linear conductors are sectioned in any shape without being limited to a circle, a rectangle, etc., and parallel linear electrodes 2 may be constituted by forming grooves in the periphery of the solid body 1 or winding or vapor-depositing a conductive material 7 on the surface of the solid body, or forming grooves 8 by machining, etching, etc. Further, an insulating film 4 is formed on the surfaces of the linear conductors 2 and an insulator 6 is charged between the conductors 2 to smooth surface, thereby obtaining the hard-to-stain and easy-to-clean surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a capacitive sensor for measuring the dielectric constant and changes in dielectric constant of a fluid.

More specifically, the present invention relates to a capacitance sensor that has a simple structure, is easy to manufacture, is hard to get dirty, is easy to clean, and is easy to measure.

(Prior art) Capacitance sensors are used as sensing means to detect the relative dielectric constant and its changes to investigate the properties and composition of fluids, the presence or absence of the fluid itself, the position of interfaces between multiple fluids, etc. It is used for the purpose of detecting changes in the dielectric constant of oils, petroleum products, lubricating oils, etc., and investigating the position of the oil level, the position of the interface between multiple liquids, the presence of water, and its properties. It is used.

Conventionally, sensors for measuring the dielectric constant of organic chemicals, organic solvents, petroleum products, lubricating oils, etc.
Electrodes for measuring the dielectric constant of insulating oil as shown in C2101, double-pipe electrodes used for process plant fluids, ship fuel systems, etc., with flat plates facing each other and fluid introduced between them. Parallel plate electrodes, sensors with a metal thin film formed on an insulator to measure humidity, sensors on an insulating flat plate to detect water droplets and humidity, and measure the dielectric constant of oils, fats, and lubricants. There are comb-shaped electrodes with minute electrode patterns formed on them, and these electrodes are immersed in a sample fluid that detects the dielectric constant of each sample fluid to determine the properties and composition of the fluid, the presence or absence of the fluid itself, and the interface between multiple fluids. It was used to investigate the location of

(Problems to be Solved by the Invention) However, in the above-mentioned capacitance sensor, a capacitance sensor that is simple in structure, easy to manufacture, and easy to measure has not been obtained, as shown in JIS C2101. Electrodes, double-tube electrodes, and parallel plate electrodes are not easy to manufacture, and because the sample fluid is introduced into a small gap for measurement, the sensor easily gets dirty during measurement and is difficult to clean. Therefore, it is difficult to miniaturize the sensor. Metal thin film sensors and comb-shaped electrodes allow for miniaturization of the sensor, are resistant to dirt, and are easy to clean, but they have the problem of requiring special technology in manufacturing, resulting in high costs.

(Means for Solving the Problems) An object of the present invention is to provide a capacitance sensor that solves the above-mentioned problems that have not been sufficiently solved in the prior art.

More specifically, it has a simple structure and is easy to manufacture.

To provide a capacitance sensor that is hard to get dirty, easy to clean, and easy to measure.

As a result of various studies aimed at solving the above-mentioned problems, the present inventors have completed the present invention by discovering that a capacitive sensor with a certain specific structure achieves this objective. That is, the gist of the present invention resides in a capacitance sensor characterized in that an electrode is formed by winding a pair of linear conductors in parallel around an insulating solid without crossing each other.

The insulating solid used in the above-mentioned sensor can be any insulating material (however, it must not dissolve or soften in the fluid to be measured), and its shape can be cylindrical, conical, or rectangular. It may have any shape such as a prism, pyramid, or flat plate, or it may have a shape in which several insulators are combined and a linear conductor is wound around it. As for the material, any solid material exhibiting insulating properties can be used, such as synthetic resin, insulating paper, rubber, mica products, ceramic products, glass, and insulating mixtures.

Further, the cross-sectional shape of the linear conductor may be any shape such as circular or rectangular, and the method of wrapping the linear conductor around an insulating solid material is to provide a groove around the solid material and wind the linear conductor. Good and
Attach a conductive substance to an insulating solid surface of any shape,
Alternatively, a linear electrode may be formed by removing a part of the conductive material in parallel lines by mechanical processing or etching after forming a conductive film through precipitation or vapor deposition. Alternatively, a coating film of an insulating material may be formed on the surface of the linear conductor, or the direction in which the conductor is wound may be reversed midway.

In order to make the sensor less likely to become dirty and to facilitate cleaning, an insulator may be filled between the linear conductor and another linear conductor to smooth the surface of the capacitive sensor.

In addition, wire-shaped conductors are usually wound in parallel without crossing each other, and the tips of each are fixed to an insulator to form an electrode, but two or more wire-shaped conductors can be wound in any It may be structured such that it is wrapped around a shaped insulating solid and joined in the middle, resulting in two terminals for the electrical conductor.

(Function) In the present invention, the capacitance sensor can be used in a manner in which a temperature measuring means is provided near the capacitance sensor, or in which two or more capacitance sensors are prepared and one of them is used as a reference sensor. , one in which the other is used as a sample sensor to detect the difference in capacitance between the two, one in which the reference sensor is immersed in a reference fluid, and one in which the reference sensor is housed in a sealed container together with the reference fluid and the difference in capacitance between the two is detected. This also includes those in which the reference sensor and the sample sensor are used under the same temperature conditions by immersing the container in the sample fluid.

The above-mentioned capacitance sensor can measure the dielectric constant of a sample fluid by simply lowering the sensor below the liquid surface while holding the measurement sample in a sample bottle, and also,
It can also be inserted midway through a fluid transfer line to continuously measure the properties, impurities, etc. of the fluid in the line.

The capacitance sensor of the present invention is used to detect the relative dielectric constant of a fluid and its change to investigate the properties of the fluid, the presence or absence of the fluid itself, and/or the position of the interface between multiple fluids. It is particularly suitable as a method for detecting the position of the oil surface of oils, petroleum products, lubricating oils, etc., the position of the interface between multiple liquids, the amount and properties of water mixed in, etc. In comparison, it is possible to reduce the size of the capacitance sensor and improve its sensitivity and accuracy, and to easily manufacture a capacitance sensor with excellent characteristics in an industrially advantageous manner.

(Examples) The present invention will be explained in more detail using Examples below, but these are merely for illustrative purposes, and the Examples do not limit the technical scope of the present invention. It is not a basis.

(Part 1) Figure 1 shows a capacitance separator as an embodiment of the present invention. This figure shows the sensor and how it is used.

A capacitance sensor was constructed by winding two insulated copper wires 2 with a diameter of 0.5 m in parallel around a polystyrene resin cylinder with a diameter of 8 m and a length of 125 mm so as not to touch each other.

The number of times the copper wire is wound is 10 times per copper wire, and the total winding width is 15 nwn in the longitudinal axis direction from the position 12.13 10 mm from the tip 11 of the insulating cylinder 1, and the interval between the wound copper wires is were all made to be the same.

Next, the sensor of this embodiment has the other end terminal 21 of the two negative copper wires.
, 22 respectively to the measurement terminals 31.3 of the LCR meter 3.
2, and a portion of the sensor was immersed in air and a diesel engine oil sample to measure capacitance.

The diesel engine oil sample is marine engine oil (
A total of 3 samples were used: 1 sample of new oil with the trade name Cosmo Marine 3040) and 2 samples of used oil of the same variety with different collection locations and usage history.

Table 1 shows the properties of each sample.

Table 1 Properties of Diesel Engine Oil Samples The temperature of the sample oil at the time of capacitance measurement was 21°C and the air temperature was 20°C.

The LCR meter used was YIIP4275A model manufactured by Yokogawa Hewlett-Packard Corporation, and the measurement frequency was 200 kHz.

The measurement results of capacitance are shown in Table 2.

Table 2 Capacitance measurement results As is clear from the measurement results, the capacitance sensor according to the present invention can not only detect the presence of lubricating oil in the air, but also detect the presence of fresh diesel engine oil. It was possible to clearly detect and distinguish the difference in capacitance between the oil and the oil used.

Similarly, the capacitive sensor according to the present invention can detect various liquids, such as organic chemicals, organic solvents, petroleum products, the presence or absence of lubricating oils, the height of the liquid level in the container, the presence or absence of leakage, and the interface of multiple liquids. It will be easily understood that it is extremely effective when used to investigate the location, etc., and to measure the composition and properties of various liquids, as well as the amount of water and impurities contained therein.

(Part 2) FIG. 2 shows an embodiment of the capacitive sensor of the present invention used as described above. Capacitance sensors with various characteristics can be easily constructed by adjusting the distance between the power supply lines and the number of turns formed by winding the shaped conductors 2 a plurality of times in parallel with each other.

Each of the Examples described below also shows the electrostatic charge (Part 3) according to the present invention.
) FIG. 3 shows an embodiment of the capacitance sensor of the present invention in which an insulating coating 4 is formed on the surface of a linear conductor 2 and a coated conductive wire is wound around a cylindrical insulator 1. show.

(Part 4) Fig. 4 shows a sensor of the present invention in which a coil-shaped groove 5 is provided around a cylindrical insulator 1, and a linear conductor 2 is embedded in the groove 5 to form a capacitance sensor. An example is shown.

The conductor 2 can also be coated with the coated conductive wire used in Example (Part 3).

Further, by matching the shapes of the cross section of the groove 5 and the cross section of the conductor 2, it is possible to completely embed the conductor 2 in the groove 5.

However, the above-mentioned type can also be obtained by the configuration described in the following example (part 5).

(Part 5) Figure 5 shows an example of a capacitive sensor formed by filling or winding the gap between a linear conductor 2 wound into a coil around a cylindrical insulator 1 with an insulator 6. shows. In this example, as in Example (Part 4), the mutual spacing between the electrodes is stable;
It is possible to construct a sensor that is extremely easy to clean or wash, and whose characteristics are not affected by washing or other external forces.

(Part 6) FIG. 6 shows 1. A thin film 7 of a conductor is formed around a cylindrical insulator 1, and the same peripheral surface is subjected to a method such as mechanical processing or etching. By forming a coil-shaped groove 8, the conductive material in the same portion was removed to form parallel linear electrodes.
This is another embodiment of the capacitance sensor of the present invention.

(Part 7) Figure 7 shows three linear conductors 2 placed around a cylindrical insulator 1.
An example is shown in which a capacitance sensor is formed by electrically independently winding coils and connecting two of them at a terminal portion.

(Part 8) Figure 8 shows a capacitance sensor of the present invention in which three square bar insulators 1 are combined to form a triangular prism, and a linear conductor 2 is wound around the structure. Another example will be shown.

(Effects of the Invention) According to the present invention, it is possible to obtain a very excellent capacitance sensor that exhibits the following special functions and effects that cannot be expected from conventionally known sensors of this type.

(1) It has a simple structure, is easy to manufacture, can be miniaturized, and has improved sensitivity and accuracy compared to sensors of the same size when used to investigate the presence, difference, or interface position of fluids. In addition, single products with different characteristics can be manufactured industrially advantageously.

(2) Measurement is simple, stain-resistant and easy to clean.

(3) Measurement of fluid in transfer piping can also be easily carried out.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an embodiment of the capacitance sensor of the present invention and how it is used, FIG. 2 is another embodiment of the sensor of the present invention in which the insulating material is cylindrical, and FIG. Another embodiment of the capacitance sensor of the present invention, in which a coating film of an insulator is formed on the surface of a linear conductor, is shown in FIG.・Another embodiment of the sensor of the present invention formed by winding, FIG. 5 shows a sensor of the present invention formed by filling an insulator between a linear conductor and another linear conductor Another example, FIG. 6, shows a linear electrode formed by removing a thin film of a conductor on the surface of an insulator in parallel lines by mechanical processing or etching. An embodiment of the sensor of the present invention, FIG. 7, shows a sensor formed by winding three linear conductors on the surface of an insulator.
Another embodiment, in which two of them are connected at the terminal part, is shown in Figure 8, in which a linear conductor is wound around an insulating frame formed by combining three insulating materials to form a triangular prism. 1 shows an example of a capacitance sensor. 1... Insulating material, 2... Linear conductor, 2
1.22...Terminal of electrical conductor, 3...LCR meter 4...Insulating coating film, 5.8...Coil-shaped groove.

Claims (1)

[Claims] A capacitive sensor characterized in that an electrode is formed by winding a pair of linear conductors around an insulating solid in parallel without crossing each other.