KR0153480B1 - Tank liquid level measuring device - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention provides an oil price strain line type liquid level measurement device capable of detecting the amount of fuel oil or the amount of humans at the bottom of the tank with fuel oil.

To this end, one end of the magnetostriction line has a coil unit in which the transmitting coil has a receiving coil installed in the measuring area. The receiving coil area is sealed with the lower end sealed in a non-magnetic metal pipe. The first float and the magnet are attached to the upper end of the pipe to seal the head of the explosion-proof structure for accommodating the circuit board, and to have a magnet on the outside of the pipe and the specific gravity of the whole is smaller than that of oil. And a second float having a specific gravity smaller than water and larger than oil is inserted in a flowable manner. The first float moves in line with the liquid level of the fuel oil, and the second float moves in correspondence with the liquid level of the water. When the ultrasonic wave is generated by exciting the transmission coil in this state, electromotive force due to the reverse magnetostriction effect is generated at the other positions where these two floats are located, so that the time until the input of these two electromotive forces is counted by a counter. If the amount of fuel oil and water are standing, the amount can be measured.

Description

Magnetostrictive tank liquid level measuring device

1 is a cross-sectional view of an apparatus showing one embodiment of liquid level detecting means used in the present invention.

2 is an enlarged cross-sectional view of the liquid level detecting means.

3 is a block diagram showing an embodiment of a liquid level measuring device using in-phase liquid level detecting means.

4 is a timing diagram showing the operation of the in-phase device.

(A) and (b) of FIG. 5 are explanatory drawing which shows operation | movement of the liquid level measuring device, respectively.

* Explanation of symbols for main parts of the drawings

1 head 3 detection unit

3: expected 4: cover

6, 7, 8: circuit board 10: cable

11: pipe 12: flange

13: float 13a: magnet

14: float 14a: magnet

15: coil unit 20: magnetostriction line

22: Transmission coil 23: Reception coil

30 measuring circuit 31 signal processing unit

33: power supply means 34: power supply line

35: transmission line

[Industrial use]

The present invention relates to an apparatus for measuring the liquid level or liquid level of a liquid contained in a tank or the like by the movement of a float.

[Prior art]

Liquid level measurement of tanks installed underground is usually carried out using a depth measuring rod, but there is a problem that it is not only necessary to rely on human hands, but also does not allow online level management. In particular, in underground tanks that store a certain amount of fuel oil at all times, there is a problem that moisture in the air condenses in the tank due to respiration, resulting in corrosion of the tank and measurement error of the storage amount of fuel oil.

In order to solve this problem, the liquid level of the fuel oil is measured by arranging the cylindrical electrodes in a concentric manner and measuring the amount of fuel oil by the capacitance between the two electrodes. As a result of the change in permittivity due to oil type or microdroplets suspended in oil, not only measurement error occurs, but also two types of detection electrodes for fuel oil detection and water detection are needed. Since the insulating electrode requires an insulation treatment, there is a problem of causing an increase in the price of the device (Japanese Patent Publication No. Hei 3-1245).

In addition, a magnet is embedded in the displacement detection means using an electric strain phenomenon by winding the receiving coil all over the measurement area around the magnetostriction line and installing the transmitting coil at the upper end. A liquid level measuring device has been proposed (a Japanese Patent Laid-Open Publication No. 59-37418) that allows a float to be tracked on the liquid level. However, if the depth to be measured is shallow, it is possible to fix both ends to the aircraft. It is difficult to apply to things that are difficult to enter and work inside, such as an installed tank, and contain a reactance component. Therefore, when measuring flammable liquids, severe explosion-proof treatment is required.

[Problem to Solve Invention]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is that magnetic deformation (self-distortion) that solves a problem at a time for practical use when converting a float movement into an electric signal using a magnetostriction phenomenon. It is to provide a wire level measurement device.

The present invention also provides a liquid level measurement device capable of detecting the liquid level measurement of fuel oil and the amount of water accumulated in the bottom portion by the same liquid level detection means.

[Means for solving the problem]

In order to solve such a problem, in the present invention, a coil is provided with a transmitting coil at one end of the magnetostriction line and a receiving coil is installed in the measuring area, and the receiving coil area is enclosed in a non-magnetic metal pipe sealed with a lower end, The upper end is sealed by molding, and the head part of the explosion-proof explosion-proof structure for accommodating the circuit board is attached to the upper end of the pipe in an airtight manner, and the float is attached to the pipe with a magnet. The first float set smaller than the oil of the total specific gravity and the second float set smaller than the water and larger than the oil were placed in a flowable manner.

[Action]

By sealing the coil of the coil of the coil unit to prevent the flammable liquid from coming into contact with the coil of the coil unit, it is also isolated from the external environment by cooperating with the head of the pressure-resistant explosion-proof structure attached to the pipe to prevent explosion. To realize.

The first float moves in correspondence with the liquid level of the fuel oil, and the second float moves in correspondence with the liquid level of water accumulated under the fuel oil.

When the ultrasonic wave is generated by exciting the transmission coil in this state, the electromotive force due to the reverse magnetic deformation effect is generated between the positions of the two floats, so the time between the excitation point and the electromotive force generated at different times at the positions of the two floats is measured. By doing so, the level of fuel oil and the level of water can be measured.

EXAMPLE

The following describes the details of the present invention based on examples.

FIG. 1 shows an embodiment of the liquid level measuring apparatus of the present invention, which is composed of two parts, a head part 1 and a detection part 2. As shown in FIG.

The head part 1 is configured as a case of explosion-proof structure by fixing the base 3 and the cover 4, which hold the detection part 2, with the packing 5 therebetween, and having a signal processing circuit described later inside. The printed circuit boards 6, 7 and 8 are connected to a control device to be described later by a cable 10 which is hermetically pulled out by the packing 9.

Reference numeral 2 has a pipe 11, which will be described later, and a flange 12 formed on the upper side as a detection unit, and is hermetically fixed to the base 3 of the head 1 with the flange 12 therebetween. Outside the pipe 2, the 1st, 2nd float is provided so that a movement to an axial direction is possible.

The first float 13 and the second float 14 are each provided with ring-shaped permanent magnets 13a and 14a, and the first float 13 has its apparent specific gravity, that is, the specific gravity as a whole to be measured. It is selected to be smaller than fuel oil, and the second float 14 is set so that its apparent specific gravity is smaller than water and larger than fuel oil. The lower limit of the first float 13 is set above the second float 14 by the stopper 13b, and the second float 14 is attached to this float 14 in the present embodiment. The lower limit is set by the stopper so that the attached magnet 14a is located further below the lower end of the coil unit 15, which will be described later, and even in the case where the fuel oil is minimal, the floats 13 and 14 are provided. The magnet 13a of the first float 13 has a second float on top of the float 13 to prevent mutual interference of the magnetic fields by the magnets 13a and 14a so that fuel oil and water can be reliably detected. The magnet 14a of 14 is attached to the lower part of the float 14. As shown in FIG.

The coil unit 15 is inserted into the pipe 11 via the thread-shaped body 16 which also functions as a damper member, and the coil unit 15 is arrange | positioned on the substantially centerline of the pipe 11.

2 is an enlarged view of the above-described detection unit 2, 20 is a magnetostriction line made of nickel alloy, and the surface thereof is covered with a tubing 21 of synthetic resin serving as an insulator, and the surface thereof is disposed on the upper side. The reception coil 23 is wound around the transmission coil 22 over the entire length with a constant pitch from the transmission coil 22 to the front end side. The surface of these coils 22 and 23 is covered with a heat shrinkable synthetic resin tube 24 for fixing the coil, and integrated into the coil unit 15.

In the drawing, reference numeral 11 denotes the pipe described above, which is made of a non-magnetic metal having a sensitivity enough to cope with an external force, and in this embodiment is made of stainless steel, and an opening 25 at one end thereof is a metallic plug 26. ) Is inserted and fixed by solder, and the other end is inserted into the through hole of the flange 12 so that the front end of the pipe 11 is positioned to be almost the same as the face of the flange 12, and then the top of the flange 12 is The surface 12a and the lower end surface 12b are fixed together with the pipe 11 by soldering.

In the pipe 11 configured as described above, the coil unit 15 is wound on its surface with a relatively thick and elastic yarn shape at a rough pitch, so that at least a part of the receiving coil 23 and the transmitting coil 22 are wound. ) Is pulled out to the extent that it is exposed to the top, and the upper end of the pipe 11 is molded with a synthetic resin sealant 27, and the tip of the coil unit 15 is also sealed by a synthetic resin 28 having the same shape. The internal and external environment of the pipe 11 is blocked.

These transmitting coils 22 and receiving coils 23 are connected to the measuring circuits of the circuit boards 6, 7 and 8 via the flexible cables C, respectively. Reference numeral 29 in the figure denotes a ring-shaped permanent magnet for bias provided on the surface of the transmission coil 22.

3 shows an example of a signal processing circuit accommodated in the head unit 1 for driving the apparatus. In the drawing, reference numeral 30 is a measuring circuit, and the signal processing unit 31 and the starting circuit 32 It is composed by. The starter circuit 32 receives power supply from the power supply unit 33 by the power supply line 34 to maintain the always operating state, and the power supply means when the start pulse is input from the transmission line 35 to be described later. The electric power of 33 is supplied to the signal processing part 31, and it is comprised so that it may be started.

On the other hand, the signal processing unit 31 is always configured to be in a stopped state, start waiting for power supply from the start circuit 32, and stop at the end of the measurement operation.

Next, the signal processor 31 will be described again.

In the figure, reference numeral 36 denotes a driving pulse generation circuit, which outputs an excitation pulse having a constant period, for example, a pulse width of 5 microseconds, at a repetition period of 10 milliseconds, and (37) by an inverse magnetic deformation effect. The first detection circuit detects the first electromotive force induced by the receiving coil 23 (FIG. 4, R ₁ ), that is, the first float 13. Reference numeral 38 denotes a first flip-flop circuit, which is set at the time point at which the driving pulse is output and is reset by a signal from the first detection circuit 37. Numeral 39 is a first gate circuit, and the time signal from the time clock generator 40 is output in accordance with the duration of the pulse output in the set state of the first flip-flop circuit 38. It is configured to output to the counter 41. Reference numeral 42 denotes the number of time counters from the transmission coil 22 stored in the first data storage means 43 to the reference measurement point, for example, the lower surface 12b of the flange 12 as the first calculation means. The liquid level or the liquid level of the fuel oil is calculated on the basis of predetermined data such as the length per count, and the result is output to the control device 57 via the interface 44.

Reference numeral 50 in the figure denotes the second (fourth, R ₂ ), i.e., when two electromotive force is generated in the receiving coil 23 by one drive pulse as the second detection circuit. It is comprised so that the thing by the float 14 of 2 may be detected. Numeral 51 is a second flip-flop circuit, set at the time when the drive pulse is output, and configured to be reset by the signal from the second detection circuit 50. Reference numeral 52 denotes a second gate circuit, which counts the time signal from the time generation circuit 40 in accordance with the duration of the pulse output in the set state of the second flip-flop circuit 51, and the second counter. It is configured to output to 53. Reference numeral 54 denotes a second calculation means based on predetermined data such as the count time from the transmission coil 22 stored in the second data storage means 55 to the reference measurement point, the length per one count, or the like. It is configured to calculate the liquid level or the liquid level of water accumulated in the lower part of the tank and output the result to the controller 57 via the interface 44.

57 is a control device connected to the measuring circuit 30 by a transmission line capable of common bidirectional communication with one or more liquid level measuring devices, for example, a transmission line 35 of RS-485, and manually operated by a switch. each measurement cycle T ₀ and a predetermined operation is configured to output the activation signal (FIG. 4 I).

Next, the operation of the apparatus configured as described above will be described.

The head 1 is fixed to the upper end of the tank via the head 1 so that the pipe 11 is in a vertical state. Thereby, the coil unit 15 is arrange | positioned in the state positioned on the center axis line of the pipe 11 by the thread-shaped body 16. As shown in FIG. In this state, since the pipe 11 is sealed by the stopper 26, the liquid end state is maintained, and the other end is kept in the airtight state by the synthetic resin sealant 27 and the head part 1. Therefore, intrusion of flammable gas in the atmosphere into the pipe 11 or the head space is prevented. When the attachment of the liquid level detecting means is completed, it is connected to the control device 57 and the power supply means 33 by the transmission line 35 and the power supply line 34.

In the normal operation state, only the start circuit 32 operates, and the signal processing circuit 31 maintains a pause (stop) state.

If the start signal (FIG. 4I) is output based on the measurement period or the switch of the control device 57 is operated in such a state of rest, the start circuit 32 supplies the electric power supplied by the power supply line 34. Is supplied to the signal processing circuit 31. As a result, the driving pulse S is outputted from the driving pulse generating circuit 36 at a predetermined period (Fig. 4 II), and a magnetic field is generated in the transmission coil 22 so that mechanical deformation is instantaneously generated in the magnetostriction line 20. Occurs. This deformation becomes a small wave, that is, ultrasonic vibration, and transfers the magnetostriction line 20 at a speed of about 5 km / s toward the other end. At the same time, the first and second counters 41 and 53 are reset to return to zero, and the first and second flip-flops 38 and 51 are set so that a signal is output and the first and second counters 41 and 53 are set. The gate circuits 39 and 52 are opened so that the time signal from the time generation circuit 40 is input to the first and second counters 41 and 53.

When the ultrasonic wave reaches the float 13 located in accordance with the liquid level O of the fuel oil, it receives the magnetic field by the magnet 13a attached to the float 13 and receives the magnetic field by the reverse magnetic deformation effect. Generates electromotive force. This electromotive force is detected by the first detection circuit 37 as the received signal R1 (Fig. III) and output to the first flip-flop 38. As a result, the first flip-flop 38 is reset, the gate circuit 39 is closed, and the counting of the time signal (Fig. 4V) by the first counter 41 ends.

On the other hand, the ultrasonic vibration reaching the first float 13 transfers the magnetostriction line 20 downward again. In this case, since there is no water at the bottom of the tank T (FIG. 5 a), the second float 14 is located at the lower limit, and the magnet 14a thereof is the receiving coil 23. Since it is located outside of the detectable region of E, the electromotive force by the second float 14 does not occur (Fig. 4 VI). The count time count of the first counter 41 is based on the basic data stored in the first data storage circuit 43, and the distance from the first measurement reference point to the position of the float 14, that is, the liquid level L1. Or is converted into a liquid amount and output from the input / output interface 44 to the control device 57 via the transmission line 35.

On the other hand, since the electromotive force based on the 2nd float 14 does not generate | occur | produce as mentioned above, the 2nd counter 53 counts up to an upper limit (FIG. 4VI). The second calculating means 54 judges that substantially no water exists in the tank bottom part based on this count value, and outputs this determination result to the control apparatus 57. As shown in FIG.

When the measurement period ends, the start signal stops from the control device 57, the power supply by the start circuit 32 is stopped, and the consumption of power in the signal processing circuit 31 is suppressed. Hereinafter, the start signal is output from the control device 57 at a predetermined period T ₀ , and the process described above is executed intermittently.

On the other hand, when water accumulates in the tank T, as shown in FIG. 5 (b), the first float 13 moves in accordance with the liquid level 0 of the fuel oil, and the second float 14 ) Is the boundary between the top of the water and the bottom of the fuel oil ( Go to). As a result, the magnet 14a of the second float 14 is located in the detectable area of the receiving coil 23.

In this state, the driving pulse S is output and ultrasonic vibration occurs in the magnetostriction line 20. When the ultrasonic vibration reaches the first float 13 located at the liquid level of the fuel oil, the first received signal R1 is generated and a time pulse corresponding to the time required to move this distance (Fig. 4 V). Is counted by the first counter 41. Ultrasonic vibration that has passed through the first float 13 is conveyed back to the lower side to give a liquid level of water ( A second float 14 located at) is reached. Thereby, the electromotive force based on the reverse magnetostriction effect is generated in the receiving coil 23 by the magnet 14a of the 2nd float 14 again. This electromotive force is detected by the second detection circuit 50 as the second received signal R2 (FIG. 4) and resets the second flip-flop 51, so that the second counter 53 Water level from the reference point The number of times corresponding to the time required for the ultrasonic vibration to move is counted.

The second calculating means 54 is controlled via the interface 44 in terms of the liquid level L2 or the quantity of water from the bottom of the tank T based on the data of the second data storing means 55. Output to device 57.

By intermittently repeating such an operation at a constant period T ₀ , the amount of fuel oil in the tank T and the amount of human standing in the tank bottom can be detected simultaneously with as little operating power as possible.

[Effects of the Invention]

As described above, in the present invention, a coil unit provided with a transmitting coil at one end of the magnetostriction line and a receiving coil at the measurement area is housed in a non-magnetic metal pipe which is sealed with a lower end of the receiving coil area and the upper end is molded. By sealing and attaching the head part of the pressure-resistant explosion-proof structure accommodating the circuit board at the upper end of the pipe in an airtight manner so that the magnetic float can be inserted into the pipe so that the bottom end of the coil unit does not need to be fixed. Not only can be easily installed in the existing tank, but also the explosion-proof structure can be realized with a relatively simple structure by the pipe and the head.

In addition, the first float with the specific gravity less than the oil and the second float with the specific gravity less than the water and larger than the oil are inserted into the pipe so that the float and the tank bottom part representing the liquid level of the fuel oil. Not only can the position of the float indicating the liquid level of the human body be detected by the same coil unit, but the amount of fuel oil can be accurately measured irrespective of its dielectric constant.

Claims (6)

A transmission coil is installed at one end of the magnetostriction line, and a coil unit having a reception coil is installed in the measurement area. The area of the reception coil is enclosed in a closed non-magnetic metal pipe with a sealed lower end, and the upper end is It is sealed by molding and attached to the upper end of the pipe so as to seal the head of the explosion-proof explosion-proof structure, and the first and second floats having magnetic flux are inserted into the pipe so as to be able to flow therethrough, and can flow upward. The first float to be fitted is moved to match the liquid level of the fuel oil is set smaller than the total specific gravity of the oil, the second float fitted to flow in the downward direction of the first float has a specific gravity of less than water It is set larger than oil so that it moves in accord with the liquid level of water, and also excites the transmitting coil to generate ultrasonic waves. A circuit comprising a measuring circuit for measuring the amount of fuel oil and the amount of humans at the bottom of the tank by measuring the time from the difference between the vertical position of the two floats to the input of two electromotive forces generated by the reverse magnetic deformation effect. A magnetostrictive tank liquid level measuring device characterized in that the substrate is accommodated in the head unit so that the amount of fuel oil and the amount of standing water can be accurately measured irrespective of permittivity. 2. The magnetostriction according to claim 1, wherein the coil unit is covered by a heat shrinkable rigid resin and the outer periphery of the coil unit is inserted into the pipe by winding a thread-like body at a rough pitch in the receiving coil region. Wire tank liquid level measuring device. 2. The magnetostrictive tank liquid level measuring apparatus according to claim 1, wherein a flange is fixed to the head of the pipe and is fixed to the head by a screw through the flange. 2. The magnetostrictive tank liquid level measurement device according to claim 1, wherein the magnet is provided at an upper side in the first float and at a lower side in the second float. The circuit board according to claim 1, wherein the circuit board starts driving pulses for applying driving pulses to the transmission coils, and starts the clocking by the driving pulses and stops the clocking by the signal from the receiving coils. And a counting means for converting the counted number of the counting means into a liquid amount by the liquid amount calculating means. 2. The circuit board of claim 1, wherein the circuit board comprises: driving pulse generating means for applying a driving pulse to the transmitting coil, starting time by means of the driving pulse and stopping time by a first signal from the receiving coil; One counter means and a second counter means for starting time counting by the driving pulse and stopping time counting by a second signal from the receiving coil, wherein the count number of both counter means is determined by the liquid quantity calculating means. Magnetostrictive tank liquid level measurement device, characterized in that converted to the amount of liquid.