JPH09304164A - Measuring apparatus for liquid quantity in tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a measuring apparatus in which a signal processing means is used in common when a plurality of magnetostrictive level detectors are used and which automatically selects a measuring speed or a measuring accuracy according to whether a level is changed or not. SOLUTION: A magnetostrictive level detector 2 is constituted of a pulse transmission means 24 installed at the upper end part of a magnetostrictive wire 22, of a pulse reception means 25 and of a ring-shaped magnet 19 which is installed at the outer side of the magnetostrictive wire 22 so as to be freely movable. The magnet 19 is attached to a float 20 so as to be moved by following a level inside a tank 1 to be measured. In addition, the pulse transmission means 24 is constituted in such a way that it receives a signal from a driving- pulse generation circuit 16 and that it outputs an oscillating pulse used to excite the magnetostrictive wire 22 at a constant cycle T0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tank liquid amount measuring device for measuring the liquid level of a liquid contained in a tank or the like by moving a float.

[0002]

2. Description of the Related Art Liquid level measurement in a tank buried underground or in a tank mounted on a lorry or the like is usually performed using a measuring rod, but it is necessary to rely on human hands. Moreover, there is a problem that online surface level management is not possible. In order to solve such a problem, there has been proposed a liquid level measuring device that uses cylindrical electrodes arranged concentrically and that the capacitance between the two electrodes is proportional to the liquid level. There is a problem that the capacitance tends to change due to moisture, and the data processing circuit becomes complicated in order to ensure the measurement accuracy.

In order to solve such a problem, a receiving coil is wound around the magnetostrictive wire so as to cover the entire measuring region,
Further, there has been proposed a liquid level measuring device in which a float having a magnet built-in is provided so as to follow the liquid level in a displacement detecting means using an electrostrictive phenomenon having a transmission coil at the upper end (Japanese Patent Laid-Open No. 59-59).
-37418 publication).

According to this method, since the position of the float is detected, the liquid surface can be detected with high accuracy by a relatively simple measuring circuit. However, as shown in Japanese Patent Laid-Open No. 7-49256. The surface measuring device includes a driving pulse generating means for applying a driving pulse to the transmitting coil, a counting means for starting timing by the driving pulse, and a counting means for stopping timing by a signal from the receiving coil, and a measuring coil from the transmitting coil to the reference measuring point. Since a signal processing unit including a data correction unit that stores the clock count number is required, there is a problem that the cost of the system increases when the signal processing unit is installed in a plurality of tanks. In order to solve such a problem, it is conceivable to process the reception pulses from the plurality of liquid level detecting means by the common signal processing unit via the switching means.

[0005]

However, the received pulse is generated due to an extreme change in the acoustic impedance at the end of the magnetostrictive line or due to the magnetic distortion due to the float magnet. During the transmission of the pulse to the signal processing unit through the cable, it is easily affected by noise, and sometimes a large error may occur. In order to avoid this and ensure the reliability of measurement, there is no choice but to extend the measurement time and increase the number of data to be averaged to reduce the error.

However, in order to measure the liquid level of the size of an underground tank, it takes several milliseconds for one measurement, and empirically the data of about 1,000 times is required to ensure the measurement accuracy. Is required. Therefore, it takes several seconds to obtain the final measurement results from one liquid level detector, and for example, several tens of seconds until the final measurement results from all 10 liquid level detectors are obtained. It takes some time.

On the other hand, when unloading with a lorry, the amount of liquid in the tank changes rapidly, so it is necessary to obtain a timely measurement result even if the measurement accuracy is sacrificed to a certain extent. Highly accurate measurements are required to detect leaks. In order to meet such a trade-off requirement, it is possible to manually switch the measurement cycle, but there are problems such as a switching mistake due to forgetting and a switching operation, which makes the handling troublesome.

The present invention has been made in view of such circumstances, and an object thereof is to obtain liquid amount data by a plurality of liquid level detectors for measuring movement of a float by utilizing magnetostriction phenomenon. It is an object of the present invention to provide a magnetostrictive liquid amount measuring device capable of automatically switching an output cycle in response to a change in liquid level.

[0009]

In order to solve such a problem, according to the present invention, a magnetostrictive line vertically provided in a liquid level measurement region, and a float with a magnet which moves up and down along the magnetostrictive line, Pulse transmitting means for outputting an oscillation pulse of a constant cycle to the magnetostrictive line, pulse receiving means provided in the upper end region of the magnetostrictive line, passing wave of the oscillation pulse detected by the pulse receiving means, reflection by the magnet Wave, and a magnetostrictive liquid level detector that outputs a reflected wave at the lower end of the magnetic wire as a pulse signal, and the magnetostrictive liquid level detector connected to the magnetostrictive liquid level detector and scanning at a constant cycle. Switching means for taking in the pulse signal output from the detector, and counting of the clock by the pulse signal by the passing wave of the oscillation pulse, the reflected wave at the magnet, and the pulse due to the reflected wave at the lower end of the magnetostrictive line Based on the count values of the first counter, which performs a predetermined number of accumulation operations while stopping the counting operation by the number, the second counter which accumulates the count value of the first counter a predetermined number of times, and the first counter and the second counter. Calculates the liquid level, stores it as the previous liquid level in the storage means while updating it with the liquid level, and judges the liquid level change based on whether there is a difference between the previous liquid level and the current liquid level. When the level change is detected, the liquid level based on the count value of the first counter is output as final data, and when the level change is not detected, the liquid level based on the count value of the second counter is output as final data. A calculation determining means for outputting is provided.

[0010]

By detecting the change in the liquid amount and obtaining the final data based on either the count value of the first counter or the second counter, the measurement cycle can be shortened in the former case and the latter case in the latter case. To ensure accuracy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows an embodiment of an oil supply apparatus to which the present invention is applied.
An oil storage tank 1 is provided with magnetostrictive liquid level detectors 2, 2 and 2 to be described later, and these magnetostrictive liquid level detectors 2, 2 and 2 are switched by cables 3, 3 and 3. It is connected to the means 4. A common signal processing device 5 is connected to the switching means 4, and the signal processing device 5 has a PO.
S6 and the weighing machines 7, 7, 7 are connected.

FIG. 2 shows an embodiment of the present invention. In the figure, reference numeral 4 is the above-mentioned switching means, and pulse signals from a plurality of magnetostrictive liquid surface detectors 2, 2, 2 are supplied. A plurality of liquid level detectors 2 according to a scanning signal from the receiving and scanning control means 30,
The pulse signals from 2 and 2 are output to the common signal processing unit 5 while being switched.

The magnetostrictive liquid level detector 2 includes a pulse transmitting means 24 provided at the upper end of the magnetostrictive wire 22, a pulse receiving means 25, and a ring magnet 19 movably provided outside the magnetostrictive wire 22. It is composed of and. The magnet 19 is attached to the float 20 so as to move following the liquid level in the tank to be measured 1. The pulse transmission means 24 is configured to receive a signal from the drive pulse generation circuit 16 and output an oscillation pulse (FIG. 3 (I)) for exciting the magnetostrictive line 22 at a constant cycle T0.

The drive pulse generating circuit 16 reaches the lower end of the magnetostrictive line 22 after the output pulse has passed through the pulse receiving means 25 and pulses the pulse signal (pulse Z in FIG. 3 (II)) by the reflected wave. A time T1 until the receiving means 25 receives the signal, a time T0 which is more than three times 1.0 msec in this embodiment, and 5 msec in this embodiment is 5 ms as a cycle, and an oscillating pulse is output regardless of the presence or absence of the measurement operation. ing. Accordingly, the idle time T3 = 1.5 milliseconds (T3 <T2 (= T0−
T1)) (FIG. 3 (II)) can be set longer than the time interval of the pulse signal generated due to the passing wave and the reflected wave detected by the pulse receiving means 25.

Reference numeral 30 is a scanning control means, which is configured to switch the liquid level detector 2 at a constant cycle, 100 milliseconds in this embodiment. Reference numeral 31 denotes a receiving circuit, of the pulse signals input via the switching means 4, a pulse signal X generated when the oscillation pulse transmitted from the pulse transmitting means 24 passes through the pulse receiving means 25 (see FIG.
I)) is detected to determine the measurement start time. By positively utilizing the idle time described above, the pulse signal received at the time when the pulse signal cannot be received exceeds T3 is pulse-transmitted. The pulse transmitted from the means 24 is recognized as a pulse signal generated due to passing through the receiving means 25, and the next input pulse signal is float 2
The pulse signal Z generated by the reflected wave from the lower end 22a of the magnetostrictive line 22 is recognized as the pulse signal Y generated due to the reflected wave from the position of the magnet 19 of 0. Is configured to recognize as.

Reference numeral 32 is a counter, which is a pulse receiving circuit 31.
From the clock generation circuit 34 is started by the pulse signal X from the first pulse signal from the pulse transmission means 24, that is, the pulse output from the pulse transmission means 24 has passed through the pulse reception means 25. , The subsequent pulse signal, that is, the pulse signal Y generated due to the reflected wave at the position of the magnet 19 of the float 20 (see FIG.
I)) and the pulse signal Z (FIG. 3 (II)) generated by the reflected wave at the lower end 22a of the magnetostrictive line 22, and the counting operation is performed a fixed number of times by the measurement number counter 33, in this embodiment. At the stage of counting 16 times, the counting contents are calculated by the integration counter 35 and the operation judging means 3.
6 is output.

The integrating counter 35 has an area for the number of the liquid level detectors 2 connected to the switching means 4, and the count values of the counters 32 of the respective liquid level detectors 2 are added to each other for discrimination. 96 from the counter 32 that can be stored
It has a built-in clocking means for clocking the time T required to integrate the count value for zero times, 90 seconds in this embodiment, and is configured to be reset after the lapse of this time T.

Reference numeral 36 denotes a calculation determining means, which calculates the liquid level B and the liquid level E of each tank 2 from the integrated data stored in the respective areas of the counter 32 and the integrating counter 35, and further stores it in the storing means 37. The liquid level C of the tank 2 is compared with the previous liquid level C or the liquid level D obtained based on the counter 32 before the integration time in the integration counter 35 to determine whether there is a change, and the display means And outputs to 38.

Next, the operation of the above-mentioned apparatus will be described with reference to the flow charts shown in FIGS. When the data collection amount of the integration counter 35 reaches a specified value, which is 960 times in this embodiment, that is, when the accuracy switching time T elapses (see FIG. 4).
In step a), the calculation determination means 36 sets the liquid level change flag to OFF, resets the integration counter 35, and further starts a timer that defines the data sampling amount of the integration counter 35 (step B in FIG. 4).

On the other hand, the liquid level detector 2 selected by the switching means 4 always receives the oscillation pulse (FIG. 3 (I)) of the built-in drive pulse generating circuit 16. The transmitting means 24 that has received the oscillation pulse generates a sudden magnetic field that matches the time width of the oscillation pulse to cause mechanical strain in the magnetostrictive line 22.

This distortion becomes a compressional wave which propagates toward the lower end 22a of the magnetostrictive line 22 at a speed of about 5 Km / s, and the pulse receiving means 25 causes a passing wave and a reflected wave at the position of the magnet 19 of the float 20. And pulse signals X, Y, and Z generated due to the reflected wave at the lower end 22a of the magnetostrictive line 22 are output.

The receiving circuit 31 has three types of pulse signals X,
The counting operation of the counter 32 is started by the pulse signal received after the idle time T3 (1.5 milliseconds) during which neither Y nor Z can be received, that is, the pulse signal X of the passing wave. When the compression wave propagating toward the lower end reaches the position of the magnet 19 of the float 20 at the liquid surface position and the lower end 22a of the magnetostrictive line 22, pulse signals Y and Z are generated due to the reflected waves at these positions. To do. Receiver circuit 3
1 outputs these pulse signals Y and Z to the counter 32 to stop the counting operation and integrates the clocks within one measurement cycle.

Thereafter, the counter 3 is activated by the next pulse signal X.
The counting operation of 3 is restarted, the counting operation is stopped by the next pulse signals Y and Z, and the operation of integrating the clocks in one measurement period is repeated.

When the counting operation has reached 16 times set in the counting counter 33, that is, at the end of the measurement period of 100 milliseconds, the computing means 36 stores the 16 times stored in the counter 32. The first liquid level B of the tank 2 is calculated by calculating the average of the count values of the above, and the count value of 16 times stored in the counter 32 is output to the area of the liquid level detector 2 of the integrating counter 35. And add (step c in FIG. 4).

The calculation means 36 compares the liquid level B measured this time with the previous liquid level C measured in the previous scan and stored in the storage means 37, and when there is a difference equal to or greater than the error, (Fig. 4 step d), turn on the liquid level change flag of the tank 2 (Fig. 4 step
E) Then, the previous liquid level C in the storage means 37 is updated with the current liquid level B (step F in FIG. 4).

If they match within the error range (step D in FIG. 4), the liquid level B at this time is stored at the previous liquid level C in the storage means 37 without changing the flag of the tank 2.
Is updated (step F in Fig. 4).

In this way, until the number of additions of the count value in the integration counter 35 reaches the specified value, that is, until the time T elapses (step in FIG. 4), the calculation means 36 causes the liquid for all the tanks 2 to be discharged. The on / off of the surface change flag is detected (Fig. 5, step a), and when the liquid level change flag is off, the liquid level D 90 seconds before is compared with the current liquid level B, and they match within the error range. If you want to
At the stage when the accumulated data in 5 reached 960 times (Fig.
Step c), the average E of the count values E of the integration counter 35
/ 960 is calculated to calculate the liquid level F by highly accurate measurement (step 5 in FIG. 5).

On the other hand, as a result of comparing the current liquid level B and the liquid level D 90 seconds before, if they do not match (FIG. 5, step B), the measurement mode is set to the low accuracy mode (FIG. 5).
Step E), the liquid level data acquisition cycle switching means 4
It should be possible to monitor a sudden change in the liquid level when replenishing the liquid such as a lorry in accordance with the cycle of.

When the high precision mode is set (step F in FIG. 5), the average liquid level F of the count value of 960 times is output to the display means 38 as the liquid level data of this measurement (FIG. 5). 5 steps), and when the low-accuracy mode is selected, the average liquid level B of 16 count values in one measurement period T0 is output as the liquid level data X (step 5 in FIG. 5). Move to measurement of tank 2 (Fig. 5
Step).

In this case, since the accuracy switching time T has not elapsed (step B in FIG. 4), the liquid level change flag,
Without operating the integration counter 35, one measurement period T0
In-house measurement is performed (Fig. 4, Step C).

On the other hand, when the number of times of addition of the count value in the integration counter 35 reaches the specified value (step 4 in FIG. 4).
The liquid level change flag is turned on when the calculation determination unit 36 compares the liquid level D 90 seconds before in the storage unit 37 with the liquid level B measured this time (step S in FIG. 4). (Fig. 4 Step) Liquid level D measured 90 seconds before
Is updated (step 4 in Figure 4).

On the other hand, when the liquid level D 90 seconds before and the current liquid level B coincide with each other within the error range (step 4 in FIG. 4).
H)) Check if the current liquid level change flag is on, and if the liquid level change flag is off (Fig. 4 step), exit from the low precision mode to respond to the liquid level change. Then, set a high-accuracy mode that can detect minute changes in the liquid level due to leakage (Fig. 4 step), and move to measurement that prioritizes the measurement accuracy over the speed of liquid level data acquisition, 90 seconds before The measured liquid level D is updated (Fig. 4
Step e).

On the other hand, as a result of the inspection of the liquid level change flag, if the liquid level change flag is on (step 4 in FIG. 4), the liquid level D measured 90 seconds before is updated (step 4 in FIG. 4). ).

In this way, comparison with the value D in the high precision measurement mode for all the oil storage tanks 2 is performed (see FIG. 4).
Step w), at the stage where this process is completed, move to the above-mentioned step (a) in FIG. 6, and thereafter step (a) in FIG.
The steps from (i) to (i) are repeated and the process returns to step (ii) in FIG.

[0035]

As described above, in the present invention,
A magnetostrictive line vertically laid in the liquid level measurement region, a float with a magnet that moves up and down along the magnetostrictive line, pulse transmission means for outputting an oscillation pulse of a constant cycle to the magnetostrictive line, and an upper end region of the magnetostrictive line. A pulse receiving means, a magnetostrictive liquid level detector that outputs, as a pulse signal, a passing wave of an oscillation pulse detected by the pulse receiving means, a reflected wave by a magnet, and a reflected wave at a lower end of a magnetic wire; A switching means connected to the liquid level detector to take in a pulse signal output from the magnetostrictive liquid level detector while scanning at a constant period, and a pulse signal generated by a passing wave of an oscillation pulse to start clock counting, A first counter that performs a predetermined number of accumulation operations while stopping the counting operation with a pulse signal generated by the reflected wave at the bottom of the magnetostrictive line and the second reflected signal at the lower end of the magnetostrictive line; Cow And the first counter and the second counter, the liquid level is calculated and stored as the previous liquid level in the storage means while being updated with the liquid level, and the previous liquid level and the current liquid level. The liquid level change is determined based on the presence or absence of the difference with, and when the liquid level change is detected, the liquid level based on the count value of the first counter is output as final data,
Further, since a calculation determination means for outputting the liquid level based on the count value of the second counter as final data when the change in the liquid level is not detected is provided, it is possible to change the liquid level while sharing the signal processing means. Detects the first counter, or the second
It is possible to select whether to obtain the final data based on the count value of the counter and automatically select whether to shorten the measurement cycle or ensure the accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an oil supply device to which a tank liquid amount measuring device of the present invention is applied.

FIG. 2 is a configuration diagram showing one embodiment of a tank liquid level measuring device of the present invention.

FIG. 3 is a waveform diagram showing the operation of the above measuring device.

FIG. 4 is a flowchart showing an operation of the above device.

FIG. 5 is a flowchart showing an operation of the above device.

[Explanation of symbols]

 2 magnetostrictive liquid level detector 3 cable 4 switching means 5 measuring means 6 POS 7 weighing machine 16 drive pulse generating circuit 19 magnet 20 float 22 magnetostrictive line 24 pulse transmitting means 25 pulse receiving means

Claims (2)

[Claims] 1. A magnetostrictive line vertically provided in a liquid level measurement region, a float with a magnet that moves up and down along the magnetostrictive line, pulse transmitting means for outputting an oscillation pulse of a constant cycle to the magnetostrictive line, and Outputs a pulse receiving means provided in the upper end region of the magnetostrictive wire, a passing wave of the oscillation pulse detected by the pulse receiving means, a reflected wave by the magnet, and a reflected wave at the lower end of the magnetic wire as a pulse signal. A magnetostrictive liquid level detector, a switching unit that is connected to the magnetostrictive liquid level detector and that captures a pulse signal output from the magnetostrictive liquid level detector while scanning at a constant cycle; A first counter that starts counting clocks with a pulse signal of a passing wave and stops counting operation with a pulse signal of a reflected wave at the magnet and a reflected wave at a lower end of the magnetostrictive line, and performs a predetermined number of integration operations. A liquid level is calculated based on the count values of the second counter that accumulates the count value of the first counter a predetermined number of times, and the first counter and the second counter, and the storage means stores the previous value while updating the liquid level. The liquid level change is determined based on the difference between the previous liquid level and the current liquid level, and when the liquid level change is detected, the liquid based on the count value of the first counter is detected. A tank liquid amount measuring device comprising: a determination unit that outputs the level as final data, and outputs a liquid level based on the count value of the second counter as final data when a change in the liquid level is not detected. 2. The cycle of the oscillation pulse output from the pulse transmitting means is set to be twice or more the time difference between the passing wave of the oscillation pulse detected by the pulse receiving means and the reflected wave at the lower end of the magnetostrictive line. The tank liquid amount measuring device according to claim 1, wherein an idle time during which a pulse signal is not detected by the pulse receiving means is detected to identify a reference for starting counting by the first counter.