JP3557538B2 - Liquid level measurement device - Google Patents

Description

[0001]
[Industrial applications]
The present invention is related to a liquid level measuring device, which and measured continuously variable to the liquid surface level (height) in real time depending on, for example, more details liquid amount and the flow rate in the line in the vessel related to.
[0002]
[Prior Art and Problems to be Solved by the Invention]
Conventionally, various devices have been used for detecting the liquid level in a container. For example, there is a device that measures a liquid level by attaching a ball tap to a valve and causing a ball that floats on the liquid surface to move up and down according to the liquid level. However, this device has a drawback that the accuracy of the indication may be poor due to the wear of the bearing portion of the ball tap, and it is difficult to accurately check the liquid level, and it is difficult to perform the checking work due to climate (rain, snow). Had.
[0003]
In addition, a transparent pipe for checking the liquid level is attached to the side of the container, and a device that visually checks the liquid level in the transparent pipe, or a float is floated on the liquid level in the transparent pipe, and the liquid level is set at the float position There is also a device for detecting the height of an object. However, these were also difficult to confirm accurately, and were difficult to confirm due to the weather (rain, snow). In addition, the liquid level and the position of the float and the like in the transparent pipe for confirming the liquid level are difficult to see, and there is a drawback that continuous measurement cannot be performed.
[0004]
Furthermore, a device with switches at equal intervals inside the container, a device for passing an electric current to the liquid inside the container and detecting the current with a fixed terminal provided inside, a pressure switch on the bottom of the container, A device for detecting a liquid level by detecting a pressure has also been put to practical use. However, all of these methods are dangerous because there is a switch inside the container or current flows to the liquid inside the container. In addition, there is a case where dust or the like adheres to a fixed terminal or the like inside the container, causing conduction failure, and measurement cannot be performed.
[0005]
For this reason, the present inventor has made intensive research and development in order to solve the above-mentioned problems and to provide a novel liquid level measuring apparatus capable of accurately and safely measuring the liquid level accurately. As a result, as shown in FIG. 7, when the U-shaped detection conductor 3 is immersed in the liquid 2 of the container 1 and high-frequency power is supplied between the two branched detection conductors 3 by the high-frequency oscillator 4, A short circuit between the two detection conductors 3 in a portion immersed in the liquid 2 causes a measuring device 5 to measure a changing impedance or the like, and thus conceive a method of obtaining a liquid level. The present applicant has disclosed a liquid level meter using such a measuring method or a liquid level meter using substantially the same measuring method as disclosed in JP-A-59-136622, JP-A-63-210627, and JP-A-2-49119. JP-A-4-168325 and JP-A-4-168326 were found.
[0006]
However, in such a method, the measured impedance or the like has a sine waveform, and linearity cannot be obtained. Therefore, the liquid level cannot be immediately obtained from the measured impedance or the like. That is, it is very difficult to measure the liquid level in real time and continuously, for example, it is necessary to apply the measured values of the impedance and the like to a certain conversion formula to determine the liquid surface position.
[0007]
Therefore, in order to solve the above-mentioned problem, in order to obtain a measuring device having a linear relationship with the liquid level , further research and development have been made. As a result, it is of the liquid level measuring device according to the present invention led to Ru obtained.
[0008]
[Means for Solving the Problems]
The gist of the liquid level measuring device according to the present invention is a high-frequency output unit that outputs a high-frequency current, a coil containing an open magnetic circuit type core to which a high-frequency current output from the high-frequency output unit is applied, A sensing conductor extending from one end of the open magnetic path type core and at least a part of the other end is disposed in a fluid whose liquid level is to be measured, and a change in magnetic flux passing through the sensing conductor is electromagnetically detected. Measuring means for measuring.
[0009]
In this liquid level measuring device, a coil is connected in series to the other end of the detection conductor and to a wiring connecting the other end to the measuring means.
[0010]
In the liquid level measuring device, the high-frequency output means includes an oscillator and a transformer having a toroidal core, and the high-frequency current output from the oscillator is input to a primary side wound around the toroidal core. , And output from the secondary side.
[0011]
Further, in this liquid level measuring device, a gap is provided in the toroidal core.
[00 12 ]
[Action]
The liquid level measuring device according to the present invention applies a high-frequency current output from high-frequency output means to a coil containing an open magnetic circuit type core to generate a magnetic flux, and the magnetic flux is applied from one end of the open magnetic circuit type core. The detection conductor is led to the extending detection conductor, and the detection conductor functions as a kind of antenna. On the other hand, a part of the other end side of the sensing conductor extending from the core is preferably arranged in a vertical direction in the fluid whose liquid level is to be measured, and the sensing conductor is immersed as the liquid level rises and falls. It is configured to be variable in length. Therefore, when the immersion length of the sensing conductor changes as the liquid level rises and falls, the magnetic flux passing through the sensing conductor changes, and the changed magnetic flux is measured electrically or magnetically by the measuring means. At this time, the change in the liquid level, that is, the change in the immersion length of the detection conductor, and the change in the magnetic flux of the detection conductor can be measured with linearity. Then, by previously verifying and setting the immersion position of the detection conductor, that is, the liquid level and the measurement result, the liquid level can be measured more completely immediately from the magnetic flux measurement result. This measurement can be performed continuously and in real time.
[00 13 ]
Further, in such a liquid level measuring device, by connecting a coil in series to the other end of the detection conductor and a wiring connecting the other end to the measurement means, the measured value of the change in magnetic flux passing through the detection conductor and the liquid The relationship with the surface level, i.e., the immersion length of the sensing conductor, can be displayed such that the liquid level increases with increasing measured values. Similarly, a coil is connected in series to the other end of the sensing conductor, to the wiring connecting the other end and the measuring means, and the inductance of the coil is appropriately set, so that the coil can be shortened for one type of antenna. That is, the length of the sensing conductor can be arbitrarily set. Therefore, the measurement range of the liquid level can be set appropriately.
[00 14 ]
Further, in this liquid level measuring device, the high-frequency output means is constituted by an oscillator for outputting a high-frequency current and a transformer comprising a toroidal core, and the number of turns of the primary and secondary coils in the toroidal core is appropriately set. By doing so, the magnitude of the output current can be arbitrarily set. Further, by providing a gap in the toroidal core, the magnetic flux density passing through the toroidal core can be reduced. On the other hand, the magnetic flux density passing through the toroidal core through the gap can be controlled by the coil wound around the open magnetic circuit type core provided in the vicinity of the gap provided in the toroidal core.
[00 15 ]
【Example】
It will now be described in detail with reference to the drawings liquid level measuring device according to the present invention.
[00 16]
First, as shown in FIG. 1, a liquid level measuring apparatus 10 according to one embodiment of the present invention includes an oscillator 12 for outputting a high-frequency current, a high-frequency output means including a transformer 16 including a toroidal core 14, A coil 20 wound around an open-magnetic-path core 18 to which a high-frequency current output from a high-frequency output means is applied. The coil 20 extends from one end of the open-magnetic-path core 18 and at least a part of the other end is at a liquid level. A sensing conductor 24 disposed in the fluid 22 whose level is to be measured, measuring means 26 for electromagnetically measuring a change in magnetic flux passing through the sensing conductor 24, and the other end of the sensing conductor 24, It is provided with a coil 30 connected in series to a wire 28 connecting the other end and the measuring means 26.
[00 17]
Here, the oscillator 12 constituting the high-frequency output means for outputting a high-frequency current may be any oscillator as long as it oscillates a high frequency, and particularly an oscillator that stably oscillates a high-frequency waveform having a small distortion and a constant frequency. preferable. For example, an LC oscillation circuit is particularly preferable as the oscillator 12, and an oscillation circuit using a ceramic vibrator or a crystal vibrator can be used. The high-frequency current output from the oscillator 12 is input to a primary side of a transformer 16 including a toroidal core 14. The transformer 16 composed of the toroidal core 14 is composed of a primary winding 32 and a secondary winding 34, and a high-frequency current input to the primary winding 32 is transmitted from the secondary winding 34. Output.
[00 18 ]
On the other hand, a gap 36 is formed in a part of the toroidal core 14 around which the secondary winding 34 is wound, and the secondary winding 34 extends outside through the gap 36 and opens. A coil 20 wound around the magnetic path type core 18 is formed. The width of the gap 36 formed in the toroidal core 14 is not particularly limited, and is preferably selected, for example, in a range of about 0.1 mm to 4 mm, particularly about 1 to 2 mm. The open magnetic path type core 18 is formed of a non-magnetic metal such as aluminum, and may have a shape of a pipe, that is, a hollow round bar, a solid round bar, or a square bar. is not.
[00 19 ]
One end of the open magnetic circuit type core 18 is disposed near the gap 36 of the toroidal core 14 and is fixed to a substrate or the like, and the other end is connected to the detection conductor 24. The detection conductor 24 is formed of a nonmagnetic metal such as copper, copper alloy, or stainless steel, and is formed of a material that is electrically good and is not corroded by the fluid whose liquid level is to be measured. The length of the sensing conductor 24 is set by the wavelength λ of the high-frequency current, and more specifically, the length that can resonate with the wavelength λ of the high-frequency current is set as the maximum dimension. Note that the length of the detection conductor 24 is also affected by the thickness, that is, the diameter, of the detection conductor 24.
[00 20 ]
The maximum length of the detection conductor 24 is set by the wavelength λ of the high-frequency current, and this length is arbitrarily set by the value of the coil 30 connected in series to the tip side of the detection conductor 24. That is, the detection conductor 24 functions as one type of antenna, whereas the coil 30 functions as a so-called extension coil. Therefore, by arbitrarily setting the value of the coil 30, the length of the detection conductor 24 can be arbitrarily shortened, and the measurement range of the liquid level can be arbitrarily adjusted.
[00 21 ]
The coil 30 connected to the tip of the detection conductor 24 is connected to a wiring 28, and the wiring 28 is connected to the output wiring of one of the windings 34 on the secondary side of the transformer 16, and the output wiring is connected to the secondary wiring. The other output wiring of the side winding 34 is connected to the measuring means 26. The measuring unit 26 is not particularly limited as long as it is a unit that measures high-frequency power generated on the secondary side of the toroidal core 14, and is configured by, for example, a device that measures the voltage or current on the secondary side. It is sufficient that the measuring means 26 for measuring the voltage is provided with a voltmeter. For example, as shown in FIG. 2, the measuring means 26 comprises a filter detecting circuit 38, a buffer circuit 40, a stabilizing circuit 42, and a voltmeter 44. A configuration may be adopted in which noise included in the output voltage on the secondary side is removed and the change in voltage is measured. The configuration of the measuring unit 26 is an example, and is not particularly limited.
[00 22 ]
In the liquid level measuring device 10 according to the above configuration, first, the detection conductor 24 is disposed in a tank 46 in which the fluid 22 whose liquid level is to be measured is put, or in a water channel through which the fluid 22 flows. At the same time, the oscillator 12, the transformer 16, and the measuring means 26 are arranged at predetermined positions. The tank 46 that is possibly insulated, such as the one installed on the ground, is grounded. Here, the detecting conductor 24 and the transformer 16 following the detecting conductor 24 are disposed at an upper portion of the tank 46 or the like. However, it is preferable that the oscillator 12 and the measuring means 26 are disposed at an arbitrary position away from the tank 46.
[00 23 ]
After each component is set in this manner, the oscillator 12 is operated to output a substantially constant and stable high-frequency current, which is input to the primary winding 32 of the transformer 16. The high frequency current I ₀ which is then input to the primary side winding 32 is a high-frequency current I ₁ from the winding 34 of the secondary side through the toroidal core 14 is output, is input to the measuring means 26, its voltage Read. On the other hand, the high-frequency current I ₁ flowing through the winding 34 on the secondary side of the toroidal core 14 flows through the coil 20 of the open magnetic circuit type core 18 to generate a magnetic flux, and the magnetic flux is guided to the detection conductor 24. At the same time, the magnetic flux passing from the other end of the open magnetic circuit core 18 to the gap 36 provided in the toroidal core 14 is affected.
[00 24 ]
Therefore, by immersing the tip end of the sensing conductor 24 in the fluid 22, the same effect as when the length of the sensing conductor 24 is shortened is obtained. It varies the high frequency current I ₁ is the output current. Further, the high-frequency current I ₁ output from one of the secondary windings 34 is guided to the detection conductor 24 through the coil 30 through the wiring 28, but the detection conductor 24 and the distal end of the wiring 28 , The high frequency current I ₁ is short-circuited by the fluid 22, flows through the sensing conductor 24, changes the coil 20 via the open magnetic circuit core 18, and changes the magnetic flux passing through the gap 36. . As a result, the magnetic flux change in the gap 36 is amplified by the magnetic flux passing through the toroidal core 14 is varied, a high frequency current I ₁ output from the winding 34 of the secondary side will vary greatly. Therefore, along with the read as a voltage by the high-frequency current I ₁ of the measuring means 26 which is output from the winding 34 of the secondary side, by measuring the liquid level of the fluid 22 at that location, previously determined their correspondence relationship, By performing the verification, the liquid level of the fluid 22 can be immediately measured by reading the voltage by the measuring means 26.
[00 25]
As shown in FIG. 3, the relationship between the voltage read by the measuring means 26 and the liquid level of the fluid 22 increases as the voltage increases, and the liquid level increases, and both appear linearly. That is, when the sensing conductor 24 is not immersed in the fluid 22, the reference liquid level is 0 (zero), and the voltage is measured at the lowest value. Then, the detection conductor 24 is immersed in the fluid 22, and the reference liquid level rises, and accordingly, the length of the detection conductor 24 in a portion functioning as an antenna is shortened, and at the same time, the wiring 28 and the detection conductor 24 is short-circuited by the fluid 22, and the voltage measured by the measuring means 26 increases.
[00 26]
As described above in detail, since the relationship between the measured value measured by the measuring means 26 and the liquid level of the fluid 22 is obtained with linearity, there is no need for conversion or the like, and the liquid level is measured in real time. can do. In addition, the measuring means 26 and the oscillator 12 can be installed at any positions irrespective of the liquid level measurement position, and remote measurement and remote operation can be performed. Further, it can be linked with another operating device, for example, a valve device for controlling the flow rate of a fluid, together with the measuring means 26 or in place of the measuring means 26, so that the equipment can be automated.
[00 27]
The embodiment of the liquid level measuring device according to the present invention has been described above, but the present invention is not limited to the above-described embodiment.
[00 28 ]
For example, as shown in a liquid level measuring device 48 in FIG. 4, the coil 30 shown in FIG. 1 may be removed from the tip of the detection conductor 24, and the detection conductor 24 and the wiring 28 may be directly connected. . This is because such a coil 30 shown in FIG. 1 functions as an extension coil for shortening the length of the sensing conductor 24 with respect to the sensing conductor 24 functioning as one kind of antenna, and a magnetic flux passing through the sensing conductor 24. Had the function of inverting.
[00 29 ]
Therefore, by removing the coil 30, the length of the detection conductor 24 can be increased, for example, to several meters. Therefore, the measurement range of the liquid level is widened. Also, by removing the coil 30, the magnetic flux passing through the sensing conductor 24 does not reverse, so that as shown in FIG. 5, the liquid level rises, while the voltage measured by the measuring means 26 has linearity. Will appear to decrease.
[00 30 ]
Above, the liquid level measuring device according to the present invention has been described with reference to FIG surface, the present invention is not limited to the illustrated embodiment described above of course.
[00 31 ]
For example, as the conductive material used for the detection conductor, various metals other than aluminum can be used, and examples thereof include silver, gold, copper, iron, and stainless steel. In particular, copper and aluminum are preferably used because they are moderate in price and conductivity and are difficult to rust. These metals may be used as a single metal. For example, copper may be used as an alloy obtained by appropriately mixing tin, zinc, phosphorus, or the like, or brass or copper-plated iron may be used. Further, depending on the liquid to be measured, there are cases where it is better to use a metal that is resistant to rust even at high temperatures even in the presence of an acid or alkali, and is not particularly limited. The conductive material used for these sensing conductors is more preferably a non-magnetic material.
[00 32]
In addition, as the high-frequency current output from the high-frequency output means, an alternating current generally called a high frequency may be used, and the length of the detection conductor, that is, a high-frequency current necessary to secure a measurement range of the liquid level is used. Well, there is no particular limitation.
[00 33 ]
The embodiment of the liquid level measuring device according to the present invention has been described above. Further, various additional devices such as an automatic valve opening / closing device for always keeping the liquid level constant, It becomes more convenient by incorporating an automatic opening / closing valve that can be freely adjusted, or a device that notifies the liquid level. In addition, the fluid that can be measured is not limited to water, and may be any fluid such as seawater and chemicals.In addition, the present invention is based on the knowledge of those skilled in the art without departing from the spirit thereof, and various improvements and changes are made. , In a modified form.
[00 34]
EXAMPLE An example performed using the liquid level measuring device 10 having the configuration shown in FIG. 1 will be described below. First, the oscillator 12 was adjusted to output a high-frequency current of 600 KHz and 12 V using a stabilized DC power supply. Further, using a T-200 as the toroidal core 14, a part thereof was cut to form a gap having a width of 1.6 mm, and an enamel wire having a diameter of 0.69 mm was wound 32 times on the primary winding 32. , The secondary winding 34 was wound 32 times, 32 times, 32 times, a total of 96 times. Further, an aluminum pipe having a diameter of 5 mm and a length of 107 mm was used as the open magnetic circuit type core 18, and the enameled wire was wound 92 times around a length of 87 mm around the aluminum pipe. A copper wire was used as the detection conductor 24 and the wiring 28, and a 180 μH coil was connected to the tip of the detection conductor 24. Then, the output was obtained by voltage display using KT3S manufactured by OMRON Corporation through a detection circuit as the measuring means 26.
[00 35]
Next, an empty tank 46 was placed on the floor, and the tank 46 was grounded. On the other hand, the detection conductor 24 and the like are disposed in the tank 46 so that the detection conductor 24, the coil 30, and the wiring 28 do not contact the tank 46. Thereafter, water was put into the tank 46, and the output voltage at that position was measured based on the position where the coil 30 was sufficiently immersed in the water. Next, water was poured into the tank 46, and the output voltage was measured every time the water level rose by 1 cm. The measurement results are shown in a graph and are shown in FIG. As can be seen from FIG. 6, it shows almost linearity, and a slight variation is considered to be caused by a measurement error, heat generation of the oscillator 12, an influence of an external electromagnetic wave, and the like.
[00 36]
【The invention's effect】
The liquid level measuring device according to the present invention can accurately measure the liquid level of a container or a water channel simply by switching on a measuring device installed at an arbitrary position, and includes a control device and other switches. Can be installed indoors to know the amount of liquid in a container or the like outdoors. In addition, accurate measurement results can be obtained immediately, the handling of the device is extremely simple, and safety is excellent. Furthermore, there is no conduction failure due to dust or the like, and the present invention can exhibit much higher utility than conventional liquid level measuring means.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining an embodiment of a liquid level measuring device according to the present invention.
It is a block diagram showing one embodiment of a measuring device which need use the liquid level measuring device according to the invention; FIG.
3 is a graph showing the relationship between the liquid level and the measured voltage measured I by the liquid level measuring device shown in FIG.
FIG. 4 is an explanatory diagram for explaining another embodiment of the liquid level measuring device according to the present invention.
5 is a graph showing the relationship between the liquid level measured I by the liquid level measuring device shown in FIG. 4 and the measured voltage.
FIG. 6 is a graph showing a relationship between a liquid level and a measured voltage in one example actually measured by the liquid level measuring device shown in FIG. 1;
[7] The present inventors have is a cross-sectional view for explanation of the liquid level measuring device research and development before reaching the present invention.
[Explanation of symbols]
10, 48; liquid level measurement device 12, oscillator 14, toroidal core 16, transformer 18, open magnetic circuit cores 20, 30, coil 22, fluid 24, sensing conductor 26, measuring means 28, wiring 32, primary side Winding 34; secondary winding 36; gap

Claims (4)

High-frequency output means for outputting a high-frequency current, a coil containing an open-magnetic-path-type core to which the high-frequency current output from the high-frequency output means is applied; A liquid level, comprising: a sensing conductor disposed in a fluid whose liquid level is to be measured; and measuring means for electromagnetically measuring a change in magnetic flux passing through the sensing conductor. Level measuring device. The liquid level measuring device according to claim 1, wherein a coil is connected in series to the other end of the detection conductor and a wiring connecting the other end and the measuring means. The high-frequency output means includes an oscillator and a transformer including a toroidal core, and a high-frequency current output from the oscillator is input to a primary side wound around the toroidal core, and output from the secondary side. The liquid level measuring device according to claim 1 or 2, wherein the liquid level measuring device is configured as follows. The liquid level measuring device according to claim 3, wherein a gap is provided in the toroidal core.

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