KR19980081935A - Level measurement device using differential transformer - Google Patents

Abstract

According to the present invention, a rod-shaped probe rod with a differential transformer is installed in a storage tank, and a float floating in water due to a high magnetic flux transmittance and a low specific gravity flows into the probe rod, and the float rises and falls according to the water level. The present invention relates to a water level measuring device using a differential transformer that detects a change in output of a differential transformer installed in a probe rod and measures a water level.

To this end, the present invention, in the liquid level measurement device of the liquid material stored in the storage tank, the float having the core function of the differential transformer and high magnetic flux transmittance and low specific gravity, the floating portion is floating in the liquid material, the first and second of the differential transformer The float is insulated from the coil and the float is introduced therein, and the float is provided with a probe rod for outputting a water level detection signal to the secondary coil as the float descends, and the float is detected by the water level detection signal output from the secondary coil of the probe rod. Characterized in that it consists of an electronic control unit that recognizes the position of and calculates the water level by calculating with the internally stored program.

Description

Level measurement device using differential transformer

The present invention relates to a water level measurement apparatus using a differential transformer, and more particularly, a rod-shaped probe rod having a differential transformer is installed in a storage tank, and a float floating in water due to high magnetic flux transmittance and low specific gravity inside the probe rod. This invention relates to a water level measuring device using a differential transformer that detects the output level of the differential transformer installed in the probe rod according to the position where the float rises and falls according to the water level.

In general, oil level measurement in underground tanks at gas stations and liquefied natural gas (LNG) tanks, low oil tank levels in oil refineries, large tanker tanks, general tank oil tanks, and Many methods and devices have been proposed and used to measure the levels of poisonous reservoirs and other liquids stored in tanks.

As an example, a pressure transducer is installed on the upper surface of the liquid material stored in the storage tank, and a pressure detection method for detecting the change in the water level by measuring the pressure change according to the increase or decrease of the volume of the contents is used. And there is a problem that a lot of error occurs due to the change in pressure, and also buoys on the upper surface of the liquid storage material and the buoy to detect the change in the balance weight by changing the balance weight by connecting the buoy and the counterweight outside the tank with a seal The method is used, and this buoy method is difficult to process the thread connecting the buoy and the counterweight, there is a problem in the lack of installation difficulty and precision.

In addition, a buoy floats on the upper surface of the liquid material stored in the storage tank and a laser method of measuring the change of the water level by measuring the position change of the buoy with a laser, and the light beam emitted from the buoy floated on the upper surface of the liquid material is transmitted to the light receiving unit. There is a photovoltaic type for detecting the amount of change in the water level by measuring the degree, but this method has a problem that the detection efficiency is high but the cost of the product is very high and the maintenance cost is high.

As another conventional level detection method, the ultrasonic method of measuring the amount of change in the water level by measuring the time of the carrier wave which reaches the upper surface of the liquid storage material and returns to the upper surface of the liquid storage material is absolute to the temperature change and the pressure change. There is a problem that there is a large number of possible malfunctions and error ranges, lack of precision, and other methods and apparatuses have been proposed but have not been widely used.

Another conventional water level detection method is to install a magnetic float on the surface of a liquid storage material by an electromagnetism method and cause a magnetic field distortion of the coil generated when the float rises and falls with the change of the water level. By measuring the change, such an electromagnet method has a problem that the diameter of the upper end of the storage tank needs to be widened in order to install the water level measuring device because the float outer diameter of the magnetic property floating on the surface of the liquid material is large.

In addition, there is a method to measure the water level by using the characteristic that can measure the micro displacement of the object by using the differential transformer, but this is to install the primary and secondary coils of the differential transformer in the storage tank in which the liquid material is introduced A method that can detect the change in the level of the liquid material directly is not proposed, and it is impossible to inject the magnetic flux of the primary coil into the secondary coil by injecting it into the liquid material because it is not injured in the liquid phase. Differential transformers were virtually inapplicable to the level measurement means.

The present invention is to solve the above problems, the first end and the second having two cylinders of different diameters and penetrate both ends, having the function of a differential transformer between the two cylinders of different diameters It is provided with a round rod-shaped probe rod which is formed by winding a secondary coil and then molding it, and a high-permeability magnetic flux and a low specific gravity flow into the probe rod to introduce a float of a core function floating in water, and the float rises and falls according to the water level. SUMMARY OF THE INVENTION An object of the present invention is to provide a water level measuring apparatus using a differential transformer that detects a secondary coil output change of a differential transformer installed in a probe rod according to a position, so that the level of water can be accurately measured by an electronic controller.

In order to achieve the above object, the present invention provides a liquid level measurement device for a liquid material stored in a storage tank, which has a core function of a differential transformer, a float having a high magnetic flux transmittance and a low specific gravity, and a part of which floats in the liquid material, and a differential transformer. Probe and secondary coil of the winding is insulated and the float flows inside the probe rod for outputting the water level detection signal to the secondary coil in accordance with the rise and fall of the float, and the level detection output from the secondary coil of the probe rod Characterized in that the electronic control device that recognizes the position of the float by a signal and calculates the water level by calculating with an internally stored program.

1 is an installation state of the water level measurement apparatus using a differential transformer according to the present invention

Degree.

Figure 2 is an exploded perspective view of the water level measuring device using a differential transformer according to the present invention

Degree.

3 is a level measurement device using a differential transformer according to the present invention

As a cross section of the probe,

(A) is a longitudinal sectional view of the probe rod,

(B) is a cross-sectional view of the probe rod.

Figure 4 is an enlarged cross-sectional view of portion A of Figure 3 (b).

5 is a level measurement device using a differential transformer according to the present invention

Block diagram of an electronic controller.

6 is a structure and operation principle of a differential transformer applied to the present invention.

<Explanation of symbols for main parts of drawing>

1 cable 2 cable outlet 3 cap

4: protective tube 5: storage tank 6: liquid material

10: probe rod 11, 18: first and second cylinder

12, 14, 16: first to third insulating layer 13: primary coil

15: secondary coil 19: space portion 20: float

21 body 22 air coupler 30 electronic control device

31 switch array 32 relay array 33 drive

34 control unit 35 display unit 36 amplifier

37: first filter 38: shaping circuit 39: second filter

40: A / D converter 41: driving relay 42: frequency generator

43: stabilization circuit

Hereinafter, described in detail by the accompanying drawings as follows.

1 is a cross-sectional view of an installation state of the water level measurement apparatus using a differential transformer according to the present invention, in which a liquid material 6 in a liquid state such as water, oil, or chemicals is stored in the storage tank 5. On one side of 5) is installed on the probe rod 10 for outputting an electrical signal by detecting the water level of the liquid material (6) inside the protective tube (4), the protective tube (4) is supported by the cap (3), the probe rod Cable (1) for transmitting the electrical signal output from the (10) is connected to the external electronic control device 30 through the cap (3) and the cable outlet (2).

2 is an exploded perspective view of the water level measurement apparatus using a differential transformer according to the present invention, wherein the first cylinder 11 and the second cylinder 18 having a predetermined thickness are disposed at appropriate intervals, the second cylinder 18 Inside the space) is formed a space 19, between the first cylinder 11 and the second cylinder 18, the primary and secondary coils, which are components of a differential transformer (not shown) are insulated from each other, A molding layer 17 is formed on the outside of the wound primary and secondary coils to prevent water or oil from entering the coil and to firmly fix the first and second cylinders 11 and 18 to each other. The float 20 is introduced into the second cylinder 18 to move the space 19 up and down according to the level of the liquid material.

6 is a basic structure and operation principle diagram of a differential transformer applied to the present invention, (a) is a structural diagram of a differential transformer, (b) is a circuit diagram of a differential transformer.

That is, the differential transformer is divided into a primary coil and a secondary coil, a rod-shaped core is inserted in the coil center, and the secondary coil is connected in series with reverse polarity in the middle. By changing the core up and down, the mechanical displacement value can be changed to the electrical displacement value. When a constant AC voltage Ep is applied to the primary coil, the generated magnetic flux is connected with the secondary coils S1 and S2, and the difference between the driving forces Es1 and Es2 is secondary. It is a principle that can be obtained by voltage, and the probe rod 10 is constructed by using the principle of a differential transformer that operates on this principle, where the core is used as the float 20.

Figure 3 is a cross-sectional view of the probe rod, which is an element of the water level measuring device using a differential transformer according to the present invention, (a) is a longitudinal cross-sectional view of the probe rod, (b) is a cross-sectional view of the probe rod, Figure 4 (b) A section enlarged cross-sectional view.

That is, a first insulating layer 12 such as an insulating tape or a paper tape is formed outside the first cylinder 11, and the primary coil 13 of the differential transformer is continuously formed outside the first insulating layer 12. A second insulating layer 14, such as insulating tape or paper tape, is formed outside the primary coil 13, and the secondary coil 15 of the differential transformer is constant outside the second insulating layer 14. A plurality of windings are formed at a length and a predetermined interval, and a third insulating layer 16 is stacked outside the secondary coil 15.

In addition, an output terminal of each of the plurality of secondary coils 15 is exposed to the outside of the third insulating layer 16, and a plurality of output terminals of the secondary coils 15 exposed to the outside of the third insulating layer 16 are illustrated in FIG. 2. As shown in FIG. 1, the cable 1 is connected to the electronic control device 30 through the cable outlet 2 and connected to the electronic control device 30. The molding process is performed between the third insulating layer 16 and the second cylinder 18. As the molding layer 17 is formed, the first and second cylinders 11 and 18 and the cable 1 are fixed and bound, and liquid materials are not introduced.

In addition, the float 20, as shown in Figure 3 is provided with a cylindrical body 21 is blocked on one side, one side of the body 21 is provided with an air coupler 22 that can inject and discharge air The float 20 is introduced into the space portion 19 inside the first cylinder 11 of the probe rod 10 to rise and fall according to the level of the liquid material, and the 의 of the float 20 is The high magnetic flux permeability and low specific gravity were used to submerge below the surface of the liquid and to float above the surface of the liquid.

The winding length and winding spacing of the plurality of secondary coils 15 are equal to the length of float 20 floating above the surface of the liquid.

In addition, the air coupler 22 is used to check whether the air is sealed by injecting air into the float 20. After the air is injected through the air coupler 22, the air coupler is immersed in water to check whether there is an outflow of air. When the fully sealed state of (20) is confirmed, the injected air is discharged and maintained at the same state as atmospheric pressure.

FIG. 5 is a block diagram of an electronic controller in a water level measurement apparatus using a differential transformer according to the present invention. One side of the primary coil 13 is connected to a frequency generator 42 through a drive relay 41 to drive the drive. Each of the secondary coils 15, which are configured to apply an alternating current power of 1,000 Hz output from the frequency generator 42 to the primary coil 13 through the relay 41, and are wound at a predetermined length and at predetermined intervals. On one side of the output terminal, relay switches SW1 to SWn contacted by a relay operation are connected.

And the other end of the relay switch (SW1 ~ SWn) is connected to the amplifier 36 for amplifying its signal to a predetermined level when AC power flowing in the primary coil 13 is induced to the secondary coil 15, The output terminal of the amplifier 36 is connected to a stabilization circuit 43 for removing noise and shaping a stable signal by passing only a specific frequency band of the input signal.

The stabilization circuit 43 may include a first filter 37 for passing only a frequency of a predetermined band, a shaping circuit 38 for shaping the output of the filter 37, and an output terminal of the shaping circuit 38. The second filter 39 is connected to pass a very low frequency band than the first filter 37 to make a direct current. The output terminal of the second filter 39 converts the input analog signal into a digital signal proportional thereto. The A / D converter 40 to convert is connected.

In addition, a control unit 34 is connected to the output terminal of the A / D converter 40 to analyze the water level by input data, and a control unit 34 is connected to the output terminal of the control unit 34. The plurality of relays RL1 to RLn for turning on and off the relay switches SW1 to SWn connected to the respective output contacts of the driving relay 41 and the secondary coil 15 through the drive 33 are controlled. The other output terminal of the control unit 34 is connected to a display unit 35 which displays a numerical value, a character, or a graphic of the result of being calculated and analyzed by an input signal, stored data, and a program, that is, a liquid material stored in a storage tank. do.

The controller 34 sequentially drives the plurality of relays RL1 to RLn constituting the relay array 32, and the driving time and the A / D converters of the relays RL1 to RLn which are sequentially driven. There is a built-in program to measure the water level by comparing and analyzing the data input from 40).

The operation of the water level measuring apparatus using the differential transformer according to the present invention configured as described above will be described in detail with reference to FIGS. 1 to 5.

First, as shown in FIG. 1, the probe rod 10 is built into the protection tube 4, the float 20 is introduced into the space 19 of the probe rod 10, and the cap 3 and the cable outlet 2 are provided. The cable (1) connected to the probe rod 10 through the electronic control device 30 through. At this time, according to the level of the liquid material 6 stored in the storage tank 5, the float 20 is submerged below the surface of the liquid, and the remaining liquid is floated above the surface of the liquid.

In this state, when power is supplied to the electronic control apparatus 30 shown in FIG. 5, the controller 34 initializes the system, and operates the drive relay 41 through the drive 33 in the frequency generator 42. The generated AC power of 1,000 Hz is applied to the primary coil 13 wound on the outside of the first cylinder 11 of the probe rod 10, while the control unit 34 controls the drive 33 by a built-in program. By outputting a signal to sequentially drive a plurality of relays RL1 to RLn constituting the relay array 32, each switch constituting the switch array 31 interoperating with the relays RL1 to RLn ( SW1 to SWn) are sequentially connected in the ON state.

Therefore, when the plurality of relays RL1 to RLn are sequentially driven and the corresponding switches SW1 to SWn are sequentially connected in the on state, the plurality of windings 2 outside the first cylinder 18 of the probe rod 10 are wound. The output of the differential coil 15 is transmitted to the amplifier 36 in the order of the contacts of the switches SW1 to SWn, where the output level of the secondary coil 15 is different depending on the position of the float 20.

That is, according to the characteristics of the differential transformer, the magnetic flux generated by the AC power flowing through the primary coil 13 is bridged at the point where the float 20 is located, and is induced to the secondary coil 15, and the float 20 is positioned. If not, the magnetic flux of the primary coil 13 is not induced to the secondary coil 15 so that the output of the secondary coil 14 appears only at the point where the prot 20 is located.

Therefore, the signal output from the secondary coil 15 is amplified to a certain level in the amplifier 36 and then applied to the first filter 37 to make a direct current by passing only a specific frequency band, and then through the shaping circuit 38. The shaped signal is passed through the second filter 39 to remove noise, and the DC voltage from which the noise is removed is input to the A / D converter 40 to be a digital signal proportional to the DC voltage level. The output will be converted.

Meanwhile, when the switches SW1 to SWn are sequentially connected, the controller 34 recognizes the position of the project 20 when there is an output from the A / D converter 40 at that time, and stores the internally stored program and The level of the liquid substance 6 stored in the storage tank 5 is recognized by the data, and the recognized level is displayed as a number or a letter through the display unit 35, and when connected to the computer 50, Can be saved and output to the printer.

In the water level measuring apparatus using the differential transformer according to the present invention operated in such a process, it is assumed that the float 20 is located at the portion where the third switch SW3 of the secondary coil 15 is connected as shown in FIG. 5. In detail, for example as follows.

First, when the third relay RL3 is driven while the plurality of relays RL1 to RLn are sequentially controlled, the third switch SW3 is connected in an on state, thereby winding the outside of the first cylinder 11 of the probe rod 10. The magnetic flux generated by the alternating current power flowing through the primary coil 13 is bridged by a float 20 floating above the surface of the thin liquid and wound outside the second cylinder 18 where the float 20 is located. Induced by the secondary coil 15c, this induced AC power is input to the amplifier 36 through the third switch SW3.

Therefore, the amplifier 36 amplifies the AC power output from the secondary coil 15c to a predetermined level, and is then transmitted to the first filter 37 to make a DC level by passing only a frequency of 1,000 Hz. It is shaped by passing through 38), and this signal is again removed from the second filter 39, and then input to the A / D converter 40 to be converted into a digital signal proportional to the DC voltage level and output.

Therefore, the controller 34 reads data output from the A / D converter 40 when the third switch SW3 is connected, and at this time, when the output from the A / D converter 40 is greater than or equal to a predetermined value. Recognizing that the prot 20 is at the position of the secondary coil 15c to which the third switch SW3 is connected, the level of the liquid substance 6 stored in the storage tank 5 can be checked by an internally stored program. This result is displayed on the display unit 35.

On the other hand, assuming that the float 20 is located between two secondary coils 15b and 15c as shown by the dotted line in FIG. 5, the magnetic flux generated in the primary coil 13 is interlinked by the float 20. Simultaneously induced by the two secondary coils 15b and 15c in which the float 20 is located, the induced AC power is second and third when the second and third relays RL2 and RL3 are sequentially controlled. It is input to the amplifier 36 through the switches SW2 and SW3.

Therefore, when the controller 34 sequentially controls the second and third relays RL2 and RL3, if the output is output from the A / D converter 40 by a signal of a predetermined level or more, the prot 20 may have two secondary coils. The water level of the liquid substance 6 stored in the storage tank 5 can be checked by the internally stored program by judging that it is at the points (15b) and 15c, and the result is displayed on the display unit 35.

Float according to the leak amount of the liquid material when the probe rod 10 and the prot 20 using the principle of the differential transformer used in the present invention more precisely manufactured and used in the leak detection device of the liquid material stored in the closed space ( 20) the rise and fall displacement is changed, and the change amount of 0.01 μm or more can be detected due to the characteristics of the differential transformer, so that the leakage amount of the liquid substance can be detected more precisely.

As described above, two ends are penetrated and provided with two cylinders having different diameters, and the two primary cylinders are formed by winding primary and secondary coils having a function of a differential transformer between the two cylinders having different diameters. A secondary rod of a differential transformer installed in the probe rod is provided with a round rod-shaped probe rod, and has a high saturation magnetic flux density and a low specific gravity flows into the probe rod, and floats up and down according to the water level. By detecting the output change of the coil in the electronic control device, not only can the water level be precisely measured, but it can be installed and operated at a low cost, and the semi-permanent life can be maintained.

Claims (4)

In the water level measuring device of the liquid substance 6 stored in the storage tank 5, A float 20 having a core function of a differential transformer and having a high magnetic flux transmittance and a low specific gravity so that a part of the liquid floats; Probe rods 10 for winding the primary and secondary coils of the differential transformer and the float 20 is introduced therein and outputs a level detection signal to the secondary coil as the float 20 rises and falls, Recognize the position of the float 20 by the water level detection signal output from the secondary coil of the probe rod 10, characterized in that it is composed of an electronic control device 30 to calculate the water level by calculating with an internally stored program Level measurement device using a differential transformer. The method of claim 1, wherein the probe rod 10, First and second cylinders 11 and 18 having different diameters are provided, The primary and secondary coils 13 and 15 of the differential transformer are wound around the outer circumference of the first cylinder 11 having a smaller diameter than the second cylinder 18, but the primary coil 13 is continuously The secondary coils 15 are wound at predetermined lengths and predetermined intervals, respectively. An insulating layer 12, 14, 16 is formed between the first cylinder 11 and the primary and secondary coils 13, 15, A plurality of output terminals of the primary coil 13 and the secondary coil 15 are connected by cables to draw out the first and second cylinders 11 and 18, Leveling device using a differential transformer, characterized in that the molding layer 17 is formed between the first and second cylinders (11) (18) to block the inflow of the fixed and the liquid material. The method of claim 1 wherein the float 20, It is provided with a cylindrical body 21 having a high magnetic flux transmittance and a low specific gravity, a part of which floats in the liquid material. Water level measurement apparatus using a differential transformer, characterized in that the air coupler 22 is installed on one side of the body (21). The method of claim 1, wherein the electronic control device 30, A frequency generator 42 for outputting an AC power source of 500 to 2,000 Hz, A driving relay 41 for applying the frequency output from the frequency generator 42 to the primary coil 13; A plurality of switches SW1 to SWn connected to each output terminal of the secondary coil 15; A plurality of relays RL1 to RLn for controlling the contacts of the plurality of switches SW1 to SWn, An amplifier 36 connected to the other end of the plurality of switches SW1 to SWn and amplifying a signal output from each output end of the secondary coil 15; A stabilization circuit 43 connected to an output terminal of the amplifier 36 to pass a DC component of a specific frequency band of a signal to be input to remove noise and shape and output a stable signal; An A / D converter 40 for converting the output signal of the stabilization circuit 43 into a digital signal proportional thereto; A control unit 34 for sequentially controlling the control of the driving relay 41 and the plurality of relays RL1 to RLn and reading the output signal of the A / D converter 40 to detect the water level by a built-in program; Measuring device using a differential transformer, characterized in that consisting of a display unit 35 for displaying the water level detected by the control unit (34).