JP3671307B2 - Liquid level measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a take-up type liquid level measuring device suitable for measuring a liquid level in a large tank.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a winding type liquid level measuring device using a constant tension spring is known as a liquid level measuring device for measuring the liquid level in a large tank. This liquid level measuring device is configured by attaching a float to the tip of a wire (or tape), providing a spring and sprocket for winding the wire at a constant tension in the body, and directly connecting a counter display to the sprocket. The This level gauge makes the spring tension change by the weight of the wire just above the float so that the float follows the top and bottom of the liquid level, and the length of the wire above the float is adjusted to the liquid level. Is displayed on the counter display section.
[0003]
[Problems to be solved by the invention]
However, this type of liquid level measuring device can measure the liquid level in a large tank relatively accurately without the need for auxiliary power such as electricity or air pressure. When measuring with a drop, or when the liquid level fluctuates significantly, the wire is easily detached from the sprocket or drum due to the inertia of the wire drum or sprocket, and the wire is likely to loosen. There was a problem that it was difficult to measure.
[0004]
The present invention has been made in view of the above points, and provides a take-up type liquid level measuring device capable of measuring the liquid level with high accuracy and preventing the wire from coming off. Objective.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the liquid level measuring device of the present invention has a winding drum in which a wire is wound in the measuring device main body, and the wire is drawn out from above to the liquid level to reach the liquid level. In the liquid level measuring device for measuring the distance of the wire, a wire feeding length signal generating means for generating a signal indicating the feeding length of the wire, and a liquid level detection signal are generated when connected to the tip of the wire and reach the liquid level. A liquid level detector, a rising edge detector that detects that the liquid level detector is at the rising edge, and a liquid level that is provided in the liquid level detector and transmits the liquid level detection signal toward the measuring instrument main body. Detection signal transmission means, liquid level detection signal reception means provided on the measuring instrument main body side for receiving the liquid level detection signal sent from the liquid level detection signal transmission means, and the rising end detector is a liquid level detector The wire is fed out from the state where the rising end of the liquid is detected, and the liquid level detector Until it reaches the capture wire feeding length signal from the wire feeding length signal generating means, and operation control means for calculating the distance to the liquid surface from the instrument body on the basis of the wire feeding length data, the And a power storage means provided so as to be rechargeable in a power source in the liquid level detector and charged when the liquid level detector is located at the rising end .
[0006]
[Action / Effect]
In the liquid level measuring device having such a configuration, when the liquid level is measured, the wire is fed from the winding drum, and the liquid level detector at the tip of the wire is lowered toward the liquid level. At this time, the wire feeding length signal generating means generates a signal indicating the feeding length of the wire, and the calculation control means starts the wire feeding length from the state where the rising edge detector detects the rising edge of the liquid level detector. The signal indicating is taken in. When the liquid level detector reaches the liquid level, the liquid level detection signal is transmitted from the liquid level detection signal transmitting means of the liquid level detector to the liquid level detection signal receiving means on the main body side, and the feeding of the wire is stopped. The
[0007]
The arithmetic control means is configured to feed the wire from the wire feeding length signal generating means until the wire is fed from the state where the rising edge detector detects the rising edge of the liquid level detector until the liquid level detector reaches the liquid level. The long signal is taken in, and the distance from the measuring instrument body to the liquid level is calculated based on the wire feed length data.
[0008]
In this way, instead of detecting loosening of the wire when the float arrives at the liquid level, the wire level detector is electrically detected when the liquid level detector has reached the liquid level and stops feeding the wire. It is difficult to loosen, and the distance to the liquid level can be measured with high accuracy. In addition, if a wire looseness detector that detects the looseness of the wire is provided in the measuring instrument body, even if the wire is loosened, the looseness can be detected. Thus, the wire can be prevented from coming off or entangled.
[0009]
In addition, if signal transmission is performed between the liquid level detection signal transmission unit and the liquid level detection signal reception unit by a spatial transmission unit using radio waves, light rays, or ultrasonic waves, it is not necessary to provide a wired transmission unit for the wire. It is possible to simplify the structure and prevent detachment and entanglement.
[0010]
In addition, chargeable power storage means is provided in the power supply in the liquid level detector, and when the liquid level detector is located at the rising end, the power storage means is charged, so the battery in the liquid level detector can be easily managed. Can be Further, if a capacitor is used as the power storage means, maintenance such as battery replacement becomes unnecessary.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 shows a longitudinal sectional view of the liquid level measuring device, and FIG. 2 shows a transverse sectional view thereof. Reference numeral 1 denotes a case of the measuring instrument main body, and an opening 1 a for receiving the liquid level detector 10 is formed at the bottom of the case 1.
[0013]
A winding drum 3 for winding the wire 2 is attached in the case 1, and the winding drum 3 is rotationally driven by a winding motor 4 via a speed reducer 4a. Further, the pulley 5 is rotatably mounted next to the winding drum 3, and the wire 2 drawn from the winding drum 3 is hung on the pulley 5. A liquid level detector 10 is connected to the tip of the wire 2. The wire 2 may be a tape-shaped wire.
[0014]
The pulley 5 is provided with a rotary encoder 24 that outputs a frequency signal corresponding to the rotation angle of the pulley 5 as a wire feed length signal generating means. As the rotary encoder 24, one using a magnetic sensor, an optical sensor, or the like is used, and a magnetic pole portion, an opening portion, a reflection portion, and the like are provided at predetermined intervals on the peripheral portion of the pulley 5 corresponding to these sensors.
[0015]
A storage unit 6 for storing the liquid level detector 10 is provided above the opening 1a at the bottom of the case, and one of the storage unit 6 for charging the charging unit of the liquid level detector 10 is provided in the storage unit 6. The charging terminal 7 is provided by a metal having spring elasticity. A guide pulley 9 that guides the wire 2 drawn from the pulley 5 is disposed above the storage unit 6.
[0016]
The guide pulley 9 is made of an insulated conductive metal, and a voltage is applied between the wire 2 and the guide pulley 9 to determine whether or not the wire 2 is loosened by determining a conduction state therebetween. The wire looseness detector 26 is configured. The other side of the charging terminal is formed by the wire 2 and the guide pulley 9. Further, a limit switch or the like for detecting that the liquid level detector 10 is in the rising end, that is, in the storage portion 6, is provided as the rising end detector 25 at the upper portion of the storage portion 6.
[0017]
As the upper end detector, one spring metal of the charging terminal 7 and the terminal portion 11 of the liquid level detector 10 are used, and the rising edge of the liquid level detector 10 is detected by detecting the voltage therebetween. You can also.
[0018]
A battery 30 is built in the case 1 as a power source for charging and a power source for various detection circuits. Further, a light receiving element 19 for receiving an optical signal output from the liquid level detector 10 at the time of liquid level detection is provided on the bottom of the case 1 downward. This light receiving element 19 constitutes a liquid level detection signal receiving means.
[0019]
As shown in FIG. 3, the liquid level detector 10 connected to the tip of the wire 2 is formed in a weight shape, and a terminal portion 11 that contacts the charging terminal 7 in the storage portion 6 is formed on the outer peripheral portion. Provided. Further, an electrode 13 protrudes from the bottom end of the liquid level detector 10, and a change in resistance value between the electrode 13 and one terminal portion 11 is detected to detect the liquid level. In addition, a light emitting element 14 that outputs an optical signal at the time of detection is attached upward as liquid level detection signal transmitting means on the upper part of the liquid level detector 10.
[0020]
In the liquid level detector 10, as shown in the block diagram of FIG. 4, a liquid level detection circuit 15 that detects a change in the resistance value between the electrode 13 and the terminal portion 11 and detects the liquid level, and a liquid level detection circuit 15. A circuit board including an oscillation circuit 16 that oscillates in response to a detection signal from the light source, a light-emitting circuit 17 that emits light from the light-emitting element 14 in response to an output from the oscillation circuit 16, and a power supply circuit 18 that serves as a power source for each circuit. Built in. These circuits and the light projecting element 14 constitute a liquid level detection signal transmitting means. A capacitor or a secondary battery that can be charged and stored can be used for the power supply circuit 18. Charging is performed through the charging terminal 7 and the terminal portion 11, the wire 2, and the guide pulley 9 at the rising end of the detector 10. I do.
[0021]
The measuring instrument main body having the above-described configuration is attached to the inner upper part of the large tank, and is installed so that the liquid level detector 10 is lowered from above toward the liquid level in the tank. On the other hand, a control panel of a measuring instrument that receives signals from the light receiving element 19, which is a liquid level detection signal receiving means, an encoder 24, etc., and calculates and displays measured values is separately installed.
[0022]
As shown in the block diagram of FIG. 5, the control circuit of the control panel is configured with a microcomputer as a main part, and includes a CPU 20, a ROM 21, a RAM 22, and an input / output circuit 29. The winding motor 4, the rotary encoder 24, the upper end detector 25, the wire looseness detector 26, the operation switch 27, and the light receiving element 19 are connected to an input / output circuit 29.
[0023]
The CPU 20 takes in the liquid level detection signal and the output signal of the encoder 24 based on the program data stored in the ROM 21 in advance, calculates the distance to the liquid level, and displays the measured value on the display unit 23. To do. Further, in the ROM 21, a correction coefficient corresponding to the distance data is stored in advance as table data or the like in order to correct the calculated distance data. The correction coefficient is calculated in advance from an actual measurement value and stored in accordance with, for example, the slippage of the pulley and the wire and the elongation of the wire.
[0024]
Next, the operation of the liquid level measuring device having the above configuration will be described.
[0025]
When a predetermined operation switch 27 is turned on in order to measure the distance to the liquid level in the tank, the CPU 20 enters the liquid level measurement process of FIG. 6. First, in step 100, the liquid level detector 10 is raised. It is determined whether it is at the end. If the ascending end detector 25 detects the ascending end, next, at step 110, the winding motor 4 is driven to the descending side, and at step 120, data acquisition from the encoder 24 is started.
[0026]
Thereby, the winding drum 3 is rotationally driven in the wire feeding direction, and the liquid level detector 10 at the tip of the wire 2 descends in the tank by its own weight. At this time, the pulley 5 is driven to rotate in accordance with the feeding of the wire 2, and a signal indicating the rotation angle is output from the encoder 24, and the signal is captured by the CPU 20. The distance to the surface detector 10 is calculated, and the distance is displayed on the display 23 in step 140. Such processing is repeated every predetermined time (several hundred milliseconds), and the display distance is incremented.
[0027]
On the other hand, if the wire 2 is loosened while the liquid level detector 10 is descending, the wire looseness detector 26 detects it and sends it to the CPU 20. Then, the driving of the winding drum 3 is stopped.
[0028]
When the lower part of the liquid level detector 10 reaches the liquid level, the resistance value between the electrode 13 and the terminal portion 11 changes due to the liquid, the liquid level detection circuit 15 detects the arrival of the liquid level, and the oscillation circuit 16 emits light. The circuit 17 operates, and the light projecting element 14 provided on the upper part of the detector performs a light projecting operation.
[0029]
At this time, the light receiving element 19 on the measuring instrument body side receives the optical signal indicating the liquid level detection from the light projecting element 14 and sends the received light signal (liquid level detection signal) to the CPU 20. When this liquid level detection signal is input, the CPU 20 determines that the liquid level is detected, proceeds from step 160 to step 170, stops the winding motor 4 immediately, and stops the descent of the liquid level detector 10. Then, in step 180, the distance data at that time is corrected to calculate the distance data to the final liquid level. In step 190, the distance data, that is, the distance from the upper end of the tank to the liquid level is calculated. This is displayed on the display 23.
[0030]
Thereafter, in step 200, the CPU 20 drives the winding motor 4 to the winding side, winds the wire 2 around the winding drum 3, raises the liquid level detector 10, and in step 210, the liquid level detector. 10 rises to the storage 6 of the measuring instrument main body, and when the rising end detector 25 detects the rising end, the process proceeds from step 210 to step 220 to stop the lifting operation by the winding motor 4 and the liquid of this time Complete the surface measurement.
[0031]
In a state where the liquid level detector 10 is housed in the housing portion 6, the terminal portion 11 on the outer peripheral portion thereof is connected to the charging terminal 7 of the housing portion 6, and a predetermined charging is performed between the charging terminal 7 and the wire 2. Since a voltage is applied, in this state, the charging current is supplied to the power supply circuit 18 of the liquid level detector 10 through the charging terminal 7 and the terminal portion 11 of the storage unit 6, the wire 2 and the guide pulley 9, and the power supply circuit The 18 capacitors are charged with power. The electric power charged in this capacitor is used for the next liquid level measurement.
[0032]
Thus, in order not to detect the looseness of the wire when the float arrives at the liquid level, but to electrically detect that the liquid level detector 10 has reached the liquid level and stop the winding motor 4, It is difficult for the wire 2 to loosen, and the distance to the liquid surface can be measured with high accuracy. Further, even if the wire 2 is loosened, the wire looseness detector 26 can detect the looseness of the wire. When the looseness is detected, the winding motor 4 is emergency-stopped to prevent the wire from coming off or entangled. can do.
[0033]
In the above embodiment, the liquid level detection signal detected by the liquid level detector 10 is transmitted as an optical signal to the measuring instrument main body. However, in addition to the optical signal, radio waves and ultrasonic waves can be used. By using such a space transmission means, it is not necessary to provide a wire transmission means on the wire, and the wire can be wound and fed out satisfactorily.
[0034]
Moreover, in the said Example, when the liquid level detector 10 was accommodated in the accommodating part, the capacitor | condenser for power supplies of the liquid level detector was charged through the contact charging terminal 7, but the accommodating part 6 side and liquid level detection were carried out. An electromagnetic coil that can be electromagnetically coupled is provided opposite to the measuring instrument 10 side, and the capacitor for the power supply of the liquid level detector can be charged in a non-contact manner from the measuring instrument main body side through the electromagnetic coupling of the two adjacent electromagnetic coils. it can.
[0035]
Of course, a secondary battery may be used in addition to the capacitor as the power storage power source of the liquid level detector 10.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a measuring device main body showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the measuring instrument main body.
FIG. 3 is a cross-sectional view of a liquid level detector.
FIG. 4 is a block diagram of a circuit in the liquid level detector. It is a block diagram of a control circuit.
FIG. 5 is a block diagram of a control circuit of the liquid level measuring device.
FIG. 6 is a flowchart showing a liquid level measurement operation.
[Explanation of symbols]
2-wire 3-winding drum 4-winding motor 5-pulley 6-housing portion 7-charging terminal 10-liquid level detector 11-terminal portion 13-electrode 14-light projecting device 19-light receiving device 20-CPU
24-Rotary encoder 25-Up end detector 26-Wire looseness detector

Claims (4)

In a liquid level measuring instrument that has a winding drum in which a wire is wound in the measuring instrument main body and measures the distance to the liquid level by feeding and lowering the wire from above with respect to the liquid level,
Wire feeding length signal generating means for generating a signal indicating the feeding length of the wire;
A liquid level detector connected to the tip of the wire and generating a liquid level detection signal when reaching the liquid level;
A rising edge detector for detecting that the liquid level detector is at the rising edge;
A liquid level detection signal transmitting means provided in the liquid level detector, for transmitting the liquid level detection signal toward the measuring instrument body;
A liquid level detection signal receiving means provided on the measuring device main body for receiving the liquid level detection signal sent from the liquid level detection signal transmitting means;
From the state where the rising end detector detects the rising end of the liquid level detector until the wire is drawn and the liquid level detector reaches the liquid level, the wire feeding length signal from the wire feeding length signal generating means Calculation control means for calculating the distance from the measuring instrument body to the liquid level based on the wire feed length data;
A power storage means provided so as to be rechargeable in a power source in the liquid level detector, and charged when the liquid level detector is located at the rising end; and
A liquid level measuring device comprising:   The liquid level measuring device according to claim 1, wherein a wire looseness detector for detecting looseness of the wire is provided in the measuring device main body.   3. The liquid level measurement according to claim 1, wherein signal transmission is performed between the liquid level detection signal transmitting means and the liquid level detection signal receiving means by a spatial transmission means using radio waves, light rays, or ultrasonic waves. vessel. Liquid level measuring device according to claim 1, wherein the capacitor is used to power circuitry in the liquid level detector as the accumulator unit.

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