JPS6210367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring an increase or decrease in liquid in a container such as a tank.

One way to measure the increase or decrease of the liquid contained in a tank is to install a pressure switch on the bottom of the tank and check the fluctuations in the liquid level, but this method depends on the accuracy of the sensor and the measurement accuracy. It has the disadvantage that it is greatly affected. In addition, as shown in Fig. 1, an auxiliary tank 2 is provided separately from the tank 1 to be measured, and pressure switches 3 and 4 for detecting the liquid level are attached to the bottom of each tank.
When measuring the decrease in , the solenoid valve 6 is opened in response to a command from the calculation and control unit 5 to guide the liquid in the auxiliary tank 2 to the tank 1, and the liquid level in the tank 1 is returned to its original height. There is also a method of detecting the required decrease in the auxiliary tank 2 with the pressure sensor 4 and measuring the decrease in the tank 1. In this method, accuracy can be improved by using a tank with a small cross-sectional area as the auxiliary tank 2, but on the other hand, it takes time to measure because tank 1 must be replenished by the amount reduced, and the auxiliary tank 2 has a large capacity. The disadvantage is that it requires a sufficiently large size.

This invention was made in view of the above points,
In a method of measuring the increase or decrease of liquid in a tank by replenishing the liquid to the tank to be measured,
It is an object of the present invention to provide a device for measuring the increase or decrease in liquid in a container, which allows the amount of increase or decrease in liquid to be determined without replenishing the entire amount.

Hereinafter, the present invention will be described in detail based on one embodiment of the accompanying drawings.

In FIG. 2, a tank 10 contains a liquid to be measured and has a predetermined cross-sectional area. The tank 11 is an auxiliary tank containing a liquid to be used for measurement up to an appropriate height, and has a predetermined cross-sectional area. The measurement target tank 10 and the auxiliary tank 11 are connected by an oil supply pipe 12, and a reversible rotary pump (servo pump) 13 inserted in the middle allows the liquid contained in each to be exchanged between them. It's summery.

Here, the principle of measuring increase/decrease in the present invention will be explained based on FIG. 3.

In this invention, when measuring the increase or decrease of the liquid in the tank 10, one tank is removed until the difference in the height of the liquid in both tanks 10 and 11 returns to the initial state (the reference state for measurement of increase or decrease). By replenishing the other tank with liquid and detecting the amount of replenishment at that time, the increase or decrease in the tank 10 is calculated. That is, if initially the difference in the height of the liquid in both tanks 10 and 11 is L _p as shown in FIG. 3a, then the height of the liquid in tank 10 decreases for some reason. Assuming that the state shown in Figure b is reached (the height of the liquid level at that time is indicated by Hb), when measuring the amount of loss △W, the liquid level of both tanks 10 and 11 is as shown in Figure c. The liquid is replenished from the tank 11 to the tank 10 until the difference in height returns to the initial state (that is, L _p ) shown in FIG.
Find W. Here, supply amount △W′ and decrease amount △W
The relationship is determined as follows.

As mentioned above, the tank 1 is kept in the tank 1 until the difference in the liquid level between the tanks 10 and 11 reaches the initial state L _p .
1 to tank 10, Ha: Initial height of liquid level in tank 10 (standard height for measurement of increase/decrease) Hc: Height of liquid level after replenishment in tank 10 ha: Tank 11 When hc is the height of the liquid level after replenishment in the tank 11, Ha, Hc, ha, and hc satisfy the following equation (1).

ha−Ha=hc−Hc…(1) Here, the cross-sectional area of tanks 10 and 11 is
Assuming S ₁₀ and S ₁₁ , tank 11 according to supply amount △W'
The fluctuation (decrease) in the height of the liquid level is ΔW'/S ₁₁ .
Therefore, the height hc of the liquid level after replenishment is expressed as hc=ha-ΔW'/S ₁₁ (2). Also, tank 1 due to the decrease amount △W
The fluctuation (decrease) in the height of the liquid level at 0 is △W/S ₁₀ ,
The fluctuation (increase) in the height of the liquid level in the tank 10 due to the replenishment amount ΔW' is ΔW'/ _S10 . Therefore, the height Hc of the liquid level in the tank 10 after replenishment is expressed as Hc=Ha−ΔW/S ₁₀ +ΔW′/S ₁₀ (3). Here, by substituting the above equations (2) and (3) into the first equation, ha−Ha=ha−△W′/S ₁₁ −(Ha−△W/S ₁₀ +△
W'/S ₁₀ ), and if this equation is rearranged, the relationship △W=S ₁₀ +S ₁₁ /S ₁₁ ·△W′ (6) holds true. Therefore, the supply amount△
By detecting W' and multiplying it by the coefficient S ₁₀ +S ₁₁ /S ₁₁ , the amount of decrease ΔW can be obtained. From this, it can be seen that in order to determine the amount of decrease ΔW, it is not necessary to replenish by that amount. For example, in order to find the decrease amount ΔW with a small supply amount ΔW', the value of the coefficient S ₁₀ +S ₁₁ /S ₁₁ should be set large, that is, the cross-sectional area of the tank 11 should be made smaller than that of the tank 10. . Further, even if the amount of liquid in the tank 10 increases for some reason and the amount of increase is to be determined, the amount of increase can be detected using a similar method. That is, in this case, contrary to the case of decreasing, tank 10 is refilled to tank 11 so that the height of the liquid level is the same as the initial state, the amount of replenishment at that time is detected, and a coefficient is applied to it. The amount of increase can be found by multiplying S ₁₀ +S ₁₁ /S ₁₁ .

In FIG. 2, the flowmeter 14 inserted into the oil supply pipe 12 indicates the amount of replenishment △ during the above measurement.
It detects W' and the direction of replenishment. The detection signal for the replenishment amount ΔW' is, for example, a pulse signal generated every predetermined flow rate, and the replenishment direction detection signal is, for example, a signal that has a different polarity depending on the replenishment direction.

Pipes 15 and 16 extend from the bottoms of the measurement target tank 10 and the auxiliary tank 11, respectively.
The liquid in the tanks 10 and 11 is led to a differential pressure transducer 17 through the pipes 15 and 16. The differential pressure transducer 17 has a built-in diaphragm 19 to which a strain gauge 18 is attached, as shown in FIG. Detects the difference in the height of the liquid level.

The control circuit 23 drives and controls the reversible pump 13 based on the detection signal from the differential pressure transducer 17 when performing measurements.
That is, the control circuit 13 has a built-in memory (not shown), for example, and stores the detected value of the differential pressure transducer 17 in the initial state (the state that serves as a reference for measurement) (that is, the tanks 10 and 1 in the initial state).
During measurement, the reversible rotary pump 1 is stored until the detected value of the differential pressure transducer 17 matches the stored value.
3 to replenish liquid from one tank to the other.

The counter 20 is for detecting how much liquid has been replenished from which tank to which tank during measurement. That is, a pulse generated from the flow meter 14 is applied to the count input of the counter 20 according to the amount of liquid to be replenished, and an output from the flow meter 14 is applied to the up/down input according to the direction of liquid replenishment. A signal is added thereto, and the above-mentioned detection is performed by up-counting or down-counting the pulses according to the signal.

The arithmetic circuit 21 stores the coefficient S ₁₀ +S ₁₁ /S ₁₁ and calculates the decrease in the liquid in the tank 10 by multiplying the replenishment amount ΔW′ detected by the counter by the coefficient S ₁₀ +S ₁₁ /S ₁₁ . Find the quantity ΔW. Incidentally, instead of the arithmetic circuit 21, a memory such as a read-only memory may be used to read the decrease amount ΔW corresponding to the supply amount ΔW'.

The display 22 is for displaying the amount of decrease ΔW determined by the arithmetic circuit 21.

Incidentally, in the above embodiment, the case where the liquid in the tank 10 decreases has been explained, but even when the liquid increases conversely, the amount of increase can be measured in the same way. That is, in this case, the reversible rotary pump 13
is reversely rotated, liquid is supplied from tank 10 to tank 11 until the height difference matches the initial state, and the increase amount can be found by multiplying the flow rate at that time by the coefficient S ₁₀ +S ₁₁ /S ₁₁ . can.

Further, in the above embodiment, a case has been described in which the liquid levels of the tanks 10 and 11 are set to different heights in the initial state, but the configuration can be simplified by setting the liquid levels in the initial state to be equal. I can do it. That is, in this invention, it is sufficient to replenish liquid from one tank to the other tank until the difference in height matches the initial state. This is because gravity can automatically return it to its initial state simply by opening it.
In this way, the differential pressure transducer 17 shown in FIG. 2 becomes unnecessary, and the reversible pump 13 can also be a simple valve.

As explained above, according to the present invention, liquid is pumped from one tank to the other tank until the difference in liquid level between the tank to be measured and the auxiliary tank matches the difference in height in the initial state. If the liquid is replenished, the increase or decrease in the liquid in the tank to be measured can be determined, so even if the amount of replenishment is small, the increase or decrease can be measured. Therefore, the capacity of the auxiliary tank can be reduced, and the measurement time can also be shortened. Further, if the height difference in the initial state is set to 0, the mechanism for returning the height difference to the initial state during measurement can be simplified. In particular, since no means for detecting the height of the liquid level is required, measurement accuracy is also improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional liquid increase/decrease measuring device, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a diagram for explaining the measurement principle of the present invention. FIG. 4 is a sectional view showing an example of the internal structure of the differential pressure transducer shown in FIG. 2. 10...tank to be measured, 11...auxiliary tank, 12...piping, 13...forward/reverse rotation pump, 1
4...Flowmeter, 17...Differential pressure transducer,
18...Strain gauge, 19...Diaphragm,
21...Arithmetic circuit, 22...Display device, 23...Control circuit.

Claims (1)

[Claims] 1. A main container containing a liquid and having a uniform cross-sectional area;
An auxiliary container with a uniform cross-sectional area containing a liquid of the same quality as the liquid, and the height of the main container and auxiliary container at the time of measurement, based on the difference in liquid level between the main container and the auxiliary container in the initial state. means for supplying the liquid from one container to the other container until the difference between the amounts matches the reference; means for detecting the supply amount at that time; and means for detecting the amount of liquid in the main container based on the detected supply amount. and an output means for outputting a signal corresponding to an increase or decrease in liquid in a container. 2. The output means calculates the main container by adding the cross-sectional area of the main container and the cross-sectional area of the auxiliary container and dividing the result by the cross-sectional area of the auxiliary container as a coefficient, and multiplying the detected supply amount by the coefficient. 2. The apparatus for measuring increase and decrease in liquid in a container according to claim 1, which is means for determining increase and decrease in liquid in the container.