JPH0219719A - Method and device for measuring volume - Google Patents

Abstract

PURPOSE:To improve easiness in detection and economy in equipment by connecting plural tanks through a pipe and providing a means for changing the volume of the tank in any one of the tanks. CONSTITUTION:A tank 31 for compensation is connected to a main tank 30 through a connecting pipe 32. A vent 35 having a small diameter penetrates through the upper part of the tank 30 and a volume changing means 33 is provided on the upper part of the tank 31, then the volume of the inside of the tank 31 can be changed with the action of said means 33. A gauge pressure sensor 34 for detecting the internal pressure of the tank 31 is also provided. The means 33 is driven at the frequency of the kinds as many as the tanks 30 and 31 and the variation of the pressure is detected by the sensor 34. The volume of the substance housed in at least one tank out of the plural tanks 30 and 31 can be calculated based on the detection output from the sensor 34.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to liquids, powders, granules,
The present invention relates to a volume measuring method and apparatus for measuring the volume of irregularly shaped objects, etc.

[Prior art] Conventional volume measuring devices of this type are shown in FIGS. 7 to 11.
There is something like the one shown in the figure. This conventional example will be specifically described below.

FIG. 7 shows the initial state at the start of liquid level measurement, and FIG. 8 shows the state during the process of measuring the liquid level, in which the piston (volume change means) 7 is moved to the cylinder (volume change amount) 8.
This shows the state when the object is moved to the deepest part, that is, when it is moved by the maximum stroke.

In FIG. 7, the volume of the tank 3 is v, the volume of its hollow portion, that is, the portion not filled with liquid 4, is V2, and the volume corresponding to the maximum volume change of the cylinder 8 is V. ((V,
, Vl) - Assuming that the volume of the correction chamber 9 is vl, the pressure inside the tank 3 is 20, and the valve 10 is open, P based on Poisson's law
O(Vl+VO+Vl)γ=nRT.

holds true. Note that n is the number of moles of gas in the cavity of the cylinder 8, the correction chamber 9, and the tank 3, R is the gas constant, To is the absolute temperature of the gas, and γ is the ratio of the specific heat at constant pressure to the specific heat at constant volume.

Here, when the piston 7 is moved to the maximum stroke while maintaining insulation, as shown in FIG. 8, < v0 = O and the pressure inside the tank 3 increases by ΔP0, (Pa + APo ) (Vl + Vl) γ = n RT
.

holds true. From this, P, (V2+ v(, + Vl)γ −(Po+ A
Pa) (Vl''Vl)γ...(1) Equation (1) becomes approximately, and the volume v2 of the hollow portion of the tank 3 becomes.

Next, when the valve 1o is closed in FIGS. 7 and 8, the ventilation between the correction chamber 9 and the tank 3 is completely cut off, and as described above, in FIG. 7, Po (Vo +V+)γ = n RT(.

holds true, and in FIG. 8, V. = 0, and the pressure inside the tank 3 increases by ΔPo", so (po + ΔP0°)v+γ = n RT.

holds true. As a result, P, (v, +V,)γ=(P0+ΔPa')V+γ
- (3) Equation (3) becomes approximately. Here, the volume v0 corresponding to the maximum volume change of the cylinder 8 and the volume Vl of the correction chamber 9 are known, and ΔP0
Since ° can be measured, the value of TPO can be determined. As a result, the volume (2) of the hollow portion of the tank 3 in equation (2) can be calculated, and the volume vL of the liquid 4 can be determined by VT-Vl.

Note that 3a shown in FIGS. 7 and 8 is a pipe that supplies liquid 4 such as gasoline to the engine.

Next, the structure of a specific example of an apparatus based on the principle of the invention explained above will be explained with reference to FIGS. 9 and 10. In FIG. 9, parts having the same configuration as those in FIG. 7 are designated by the same reference numerals, and their explanations will be omitted.

A piston 7 is made of a disk-shaped permanent magnet having a magnetic pole on its curved surface, and a magnetic fluid 7a is attracted to the circumferential surface of the piston.
It closes the gap with the cylinder 8, which will be described later, to prevent ventilation and reduce the friction when the piston 7 slides inside the cylinder 8. Note that ventilation may be prevented by attaching an O-ring to the circumferential surface of the piston 7. Reference numeral 8 denotes a cylinder, whose one end opening 8a communicates with the correction chamber 9, and the other end is open. 9 is the correction chamber, its volume ■1
is set to be sufficiently small with respect to the total volume v7 of the tank 3, and is set to a volume that is, for example, 10 times the maximum volume change amount of the cylinder 8, that is, the maximum volume v0 that changes due to the sliding of the piston 7. With one reciprocation of the piston 7, the internal pressure changes sinusoidally (
The correction chamber 9 is connected near the opening edge of the liquid inlet 5 of the tank 3 via the electromagnetic valve 10 and the first pipe 11 in series, and the correction chamber 9 is is set so that it can flow between the tank 3 and the correction chamber 9. Note that a part of the first pipe 11 between the liquid inlet 5 and the electromagnetic valve 10 is positioned higher than the opening edge of the liquid inlet, so that the liquid 4 is injected up to the opening edge of the liquid inlet 5. Also, the liquid 4 is set so as not to flow into the correction chamber 9. 12 is a pressure sensor;
A reference pressure chamber 12a, a detection pressure chamber 12b, a strain plate 12c that partitions both pressure chambers 12a and 12b, and is distorted in proportion to the difference in pressure between the two pressure chambers, and a strain gauge attached to the strain plate. Pressure sensor body 12d such as
The reference pressure chamber 12a is connected to the first pipe 11 in series with the cavity chamber 13''EL and the second pipe 14 of the microtube, and the cavity chamber 13 and the second pipe 14 are connected to the inside of the tank 3. The detection pressure chamber 12b is communicated with the correction chamber 9, and the pressure sensor main body 12d detects the pressure difference between the pressure chambers 12a and 12b which is applied to the strain plate 12c. 15 is a disc, which is provided with a through hole 15a,
Crank 15b for linearly reciprocating the piston 7
One end of is connected. Further, the disc 15 is connected to a rotating shaft of a motor 16, which will be described later, via a reduction gear (not shown).

Reference numeral 17 denotes an optical sensor, which is provided so as to face the through hole 15a at the maximum retracted position of the piston 7.
The through hole 15a is detected. Reference numeral 18 denotes a motor drive control circuit which receives a signal for rotating the motor 16 from an arithmetic processing circuit 21 (described later) immediately after power is turned on, and which controls the optical sensor 1.
A signal for aligning the through hole 15a of the disc 15 with the position 7 is supplied to the motor 16. Also, the drive control circuit 18
receives a signal different from the above signal from an arithmetic processing circuit 21, which will be described later, and drives the motor 16 at a constant angular velocity ω. A drive signal for rotationally driving the motor 16 is supplied to the motor 16. Reference numeral 19 denotes a band pass filter, which is set to extract and output only the frequency component corresponding to the angular velocity ω0 of the motor 16. Drift components and the like generated in the pressure sensor 12 are removed. 20 is an amplitude detection circuit which manually inputs the output of the bandpass filter 19 and detects its peak value. 21 is an arithmetic processing circuit, CPU (CENTRALP
ROCESSORUNIT), ROM (READ 0
NLY MEMORY), etc., and the amplitude detection circuit 20
The liquid level in the tank 3 is calculated by manually inputting the output and executing the following arithmetic processing, and the calculation result is supplied to the display unit 22 for display.

Next, the operation of the arithmetic processing circuit 21 will be explained based on the flowchart shown in FIG.

In FIG. 11, when the power is turned on, the process proceeds from a start step 100 to an initial setting step 101, where the CPU, etc. that constitute the arithmetic processing circuit 21 are initialized, and after a predetermined period of time has elapsed after the initial setting, the valve is closed. In the signal output start step 102, a signal for closing the valve 10 is supplied from the arithmetic processing circuit 21 to the valve 10 via a drive circuit (not shown). Next, coefficient estimation step 103
Then, the coefficient TPo value in equation (4) is estimated by reciprocating the piston 7 a plurality of times. That is, the volume ■1 of the correction chamber 9 stored in the ROM, the volume v0 corresponding to the maximum volume change of the cylinder 8, and the pressure change width Δ in the correction chamber 9 measured by the pressure sensor 12.
γPo is calculated using the formula (4), γPo=Δ
Calculate based on P o' V 1 / V 6. After the calculation, the process proceeds to step 104 for stopping the output of the valve closing signal, in which the supply of the valve closing signal to the valve 10 is stopped in order to open the valve 10, and the process proceeds to step 105 for calculating the next tank internal cavity volume. By reciprocating the piston 7 a greater number of times than the number of reciprocating movements of the piston 7 in the coefficient estimating step LQ3, in step 105, the coefficient γPo obtained in the previous step 103 is calculated from the cylinder 8 stored in the ROM. The volume corresponding to the maximum volume change of ■
. , based on the volume v1 of the correction chamber 9 stored in the ROM in the same way as the volume v0, and the pressure detected by the pressure sensor 12 P0 (average value of pressure change width of multiple reciprocating movements of the piston 7) The volume v2 of the hollow part in the tank 3 is calculated, and the process proceeds to the next liquid level calculation step 106, where the volume 2 of the hollow part in the tank 3 calculated in the previous step 105 is calculated as the total volume vT of the tank 3 stored in the ROM. The volume vL of the liquid 4 is calculated by subtracting from . Further, the process proceeds to the next liquid level signal generation step 107, and this step 10
At step 7, a signal for displaying the liquid level on the display section 22 is supplied from the arithmetic processing circuit 21, and then the process returns to step 102 for starting output of the valve closing signal. After that, the above operation is repeated periodically or non-periodically. Note that a cancel step (not shown) is provided between the step 105 of calculating the volume of the cavity inside the tank and the step 106 of calculating the liquid level, in case the volume of the cavity inside the tank 3 changes significantly.

[Operation] Next, the operation of the above configuration will be explained. When the power is turned on, the through hole 15a is connected from the optical sensor 17 to the motor drive control circuit 18.
A signal for aligning the position of the optical sensor 17 with the position of the optical sensor 17 is supplied, and the motor 16 is rotated to align the through hole 15a of the disc 15 with the position of the optical sensor 17. Note that this operation is completed within a predetermined time immediately after power is turned on. Thereafter, the valve closing signal is supplied from the arithmetic processing circuit 21 to the valve 10 to close the valve 10, and furthermore, the arithmetic processing circuit 21 sends the motor drive control circuit 18 to the motor 1.
A signal instructing the start of multiple rotations of 6 is supplied. When the signal is supplied, the motor drive control circuit 18 causes the motor 16 to rotate by the specified number of rotations in one direction at a constant angular velocity ω0, and rotates the disk 15 connected to the rotating shaft of the motor 16.
is rotated, the piston 7 reciprocates inside the cylinder 8 via the crank 15b, and sends air in a volume v1 corresponding to the maximum volume change of the cylinder 8 into the correction chamber 9. When the pressure inside the correction chamber 9 changes sinusoidally by sucking in air, the pressure in the pressure chamber 12b detected by the pressure sensor 12 changes sinusoidally as the pressure in the correction chamber 9 is transmitted, and the pressure inside the tank 3 changes in a sinusoidal manner. The difference between the pressure and the equal pressure in the reference pressure chamber 12a is detected by the pressure sensor body 12c and converted into a sinusoidal electrical signal. The signal is supplied to an amplitude detection circuit 20 via a bandpass filter 19, and its peak value is detected. The detected peak values are supplied to the arithmetic processing circuit 21 and averaged, thereby calculating the coefficient γpo.
It is stored in a register or the like within the CPU. Thereafter, the supply of the valve closing signal from the arithmetic processing circuit 21 to the valve 10 is stopped, the valve 10 is opened, and the motor 16 is rotated more times than when calculating the coefficient γpo, so that the equation (2) ) is performed, the volume of the liquid 4 in the tank 3 is calculated, and the calculation result is displayed on the display unit 22. Thereafter, the above operation is repeated, and the valve 10
Each time the coefficient γP0 is closed, the coefficient γP0 is updated and stored, and a new liquid level is calculated again.

[Problems to be Solved by the Invention] However, in such a conventional volume measuring device, in order to estimate the coefficient γP0, the tank and the correction chamber 9 are connected via the valve 10, which reduces the overall efficiency of the device. There was a problem that the shape became large.

Furthermore, if a valve 10 with a small opening cross-sectional area is used, the flow resistance becomes large, and when the valve 1° is opened and pressurized, the correction chamber 9 is connected to the cavity in the tank 3. There is a problem that the piston 7 is not regarded as a space but becomes a separate space, which causes measurement errors.To avoid this, the drive angular frequency ω of the piston 7 is changed. There is a problem in that if the value is made very small, the measurement time becomes long. Therefore, it may be possible to use a valve with a large opening cross-sectional area, but this poses the problem of increased costs.

[Means for Solving the Problems] The present invention has been made by focusing on such conventional problems. A means for changing the volume is provided, and the means is driven at the same number of frequencies as the number of the tanks, the pressure fluctuation is detected by a pressure sensor, and based on the detection output, the number of the plurality of tanks is changed. An object of the present invention is to provide a volume measuring method and device for calculating the volume of at least one content in a tank.

Embodiments] Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 6.

30 is an irregularly shaped main tank that stores, for example, liquid, powder, granules, irregularly shaped objects, etc., and this main tank 3
0 is connected to a correction tank 31 via a connecting pipe 32. Further, a small diameter ventilation hole 35 is bored in the upper part of the irregularly shaped main tank 30. A volume changing means (mechanism) 33 such as a piston, a bellows, a diaphragm, etc. is provided in the upper part of the correction tank 31,
Due to the operation of this volume change mechanism 33, the correction tank 31
The volume inside can be changed.

In addition, in FIG. 5, a gauge pressure sensor 34 for detecting the internal pressure within the correction tank 31 is provided.

[The above is the configuration of this embodiment, and next, the principle of measurement using the configuration will be explained.

Measurement principle (1) Consider a connected tank system as shown in Figure 1. It consists of two types of tanks with volumes,V,,,V,. The tanks 31.30 are connected by a pipe 32 with a flow resistance rl and a flow resistance r2 of the vent 35 of the tank 30. Let γ be the specific heat ratio of the gases in both tanks 30 and 31, R be the gas constant, and τ be the thermal time constant of the tank 31. A volume change mechanism 33 using a piston, diaphragm, bellows, etc. is attached to the tank 31, and the amount of volume change actually generated by this volume change mechanism 33 is expressed as v (t
).

If the tank 30.31 is a rigid body, the tank 30.31 will not be distorted when the tank is pressurized and depressurized, so the amount of volume change of the piston, diaphragm, bellows, etc. vo(t) and the amount of volume change that actually occurs v(t) are equal. If the tank 30 is flexible, the tank 30 will be distorted when the tank is pressurized and depressurized, so that +-)v(t) will be smaller than VO(t) according to the volume change due to its contraction or expansion.

When v(t)=O, the absolute pressure, temperature, and solubility of the gas in the tank 31 are P, respectively. ,T,,n,,Tank 3
po, T2. Let it be n2. If the measurement environment does not change significantly, the gas circulates in and out of the tank 31.30 through the vent hole 35, so that the absolute pressure p0 is equal to the outside pressure, and its change is very slow and equal to the outside pressure.

When v (t)≠0, the pressure, temperature, and number of moles also change depending on the situation of the volume change mechanism, and in the tank 31, the pressure is p. +Δp+(t).

The temperature is T1+Δ”r+(t), the number of moles is nt −Δn,
x (t).

In the tank 30, the pressure is p0+Δp2 (t).

The temperature is T2◆ΔT2 (t), the number of moles is n2”Δn
l 2 (t) −Δn2 (t). Δn+
2(t) is the number of moles of air that flowed from the tank 31 to the tank 30, and Δn2ft) is the number of moles of air that leaked from the tank 30 to the outside via the vent hole 35.

We now make the following assumptions about this system.

1) The gas in the tank is an ideal gas.

2) v (t) < (V+, V2) 3) The heat capacity of the tank 30 is large <, the temperature change inside the tank due to the pressure change ΔP2 (t) is the rate of change of the volume change v (t) It is very slow and can be ignored.

4) The rate of change of the volume change amount v (t) is such that the pressure that changes accordingly is the same throughout the tank 30.31.

5) Even if an object to be measured is placed in the tank 30, the object does not create two or more closed gas spaces, that is, a hollow portion, in the tank 30.

The above assumptions do not pose any significant restrictions.

Δp+(t), Δpz(
t), ΔT l (t), ΔT2(t), Δn+2(t
) The change in Δrlz(t) is originally expressed by a nonlinear equation, but according to assumption 2), its magnitude is p. ,TI,T2,
It is very small with respect to nl and n2, so it can be approximated by a linear equation. In a static state, the relationship between the pressure, temperature, and number of moles of gas in the tank 30.31 is expressed by the following algebraic equation.

11oV+=n+RT+, 9oVz=n2RT2(
la) Also, from assumptions 1), 3), 4), and 5), in the dynamic state, the relationship between the pressure, temperature, and number of moles of the gas in the tank 30.31 is expressed by the following linear ordinary differential equation. .

(lb) (ldl Flow resistance r1 In the above equation, rl.rz is determined from the length I and diameter d of the pipe 32 as shown in the following equation.

This formula shows that the length 1 is 50 to 650 mml, and the diameter d is 2
．． This was experimentally determined using an aluminum pipe of 0 to 9.0 [ml/1 liter].

Further, the volume change v (t) is expressed as follows.

v (t) = Vo (t) − Δv (t)
(xh) ΔV is a tank-specific constant determined from the material, shape, volume, etc. of the tank, and Δv (t) is the volume due to expansion and contraction of the tank due to changes in the volume change amount Vo (t) of the volume change mechanism 33. It is the amount of change.

Applying Laplace transform to equations (1a) to (11), input v(
The transfer function from t) to the output Δp+(t) is determined as follows.

ΔT, (,0)=0 (1f) (2a) The coefficient r2Vz/RT2. r+Vi/RTa
, r, V+/RT+ is the time constant of pressure change. For example, r2V2/RT2 is a time constant of pressure attenuation when gas at the absolute temperature T2 in the hollow portion of the tank 30 flows out of the tank 30 through the vent hole 35 having a flow resistance r2. The correction coefficient 2 (s, r, rz, Vt, V,) changes depending on the volume v2 of the main tank 30, but as shown in FIG. ) In the frequency characteristics, select an appropriate frequency, for example, 4× of section A.
By choosing a frequency of 4 to 10-' Hz, it can be approximately regarded as a constant.

``r <<< j 2 (r 2 is the flow resistance of the ventilation hole 35 for air, etc.) and rz (V + ◆ old nV
, )/RT, have similar values, the following angular frequencies exist.

(2c) Under this condition, the correction coefficient is 2 (S+rl+r2+VI
.

V2) is approximated as follows.

l k, (ia+, rl, rz, V,, V2) l
41jk2 (ia+, rl, rz, Vl, V2)
= O(2d) Therefore, when the condition of equation (2c) is satisfied, the transfer function from the human power v (t) to the output Δp+(t) is γpo / (V + +v2+ΔV).

Note that when the volume change mechanism 33 is driven in a sinusoidal manner at an angular frequency ω0, it is considered to be equivalent to a state in which is occluded. pipe 32
This is considered to be equivalent to a state in which the area is blocked.

That is, the frequency of the volume change mechanism 33) (28) may be sufficient.

(2) Next, consider a single tank system as shown in Figure 3. This corresponds to a case in which the cross-sectional area of the pipe 32 connecting the tanks 31 and 30 in FIG. From this, from v (t) in Fig. 3, Δp2
The transfer function up to (t) is rl−0 in equation (2a)
, T2-T1, Δp2=Δp1, v2'=v, +V2, as follows.

here, (2g) becomes. Consider the following angular frequency ω.

For example, in the frequency characteristics of Fig. 4, 10""H shown at A
The frequency is higher than z. By setting such a frequency, the correction coefficient (iω, T2°V,°) is approximated as follows.

kl (Iω+r2+v3°) l #1. .

l kl (iω, T2.V3') 40
(2h) At this time, the transfer function is γI)O/(V2'
+ΔV).

Next, the above principle will be explained based on a specific example shown in FIG.

In FIG. 5, the correction tank 31 corresponds to the tank 31 in FIG.
, ) at the same time (VoSinωut+vosinωHt)
, or alternately (Vosinωsitv(,sinω1.
t) At high angular frequency ω□, the flow resistance r1 becomes very large according to equation (2e), so the pressure change is not transmitted to the main tank 30, and the pipe 32 is substantially connected to the correction tank 31 and the main tank 30. Since the pipe 32 becomes an air vent with extremely large flow resistance, pressure changes in only the correction tank 31 can be measured, and in this case, the theory of the single tank system shown in FIG. 3 is applied.

Here, the volume of the correction tank 31 is Vl, and the volume of the gas in the main tank 30 is V2. The volume of the liquid in the main tank 30 is V L , the correction tank 31 and the main tank 30
Let the sum of the volumes be ■7.

The pressure change Δp'+(t) in the correction tank 31 is expressed by the formula (2h)
Using an angular frequency ωH that satisfies the following, 9°Δ9+ (t) = y l kl l vos
in(ωHt+φl)■+ΔV O = y v(, sinωHt (3a)
becomes. In addition, the main tank 30 is a rigid body, that is, Δv
= 0, and when the angular frequency ω satisfies equation (2C), Δ
p+(t) becomes as follows.

At the next lowest angular frequency ω, the flow resistance of the pipe 32 becomes smaller, and the correction tank 31 and the main tank 30 are connected by a very thick pipe, so the pressure change in the correction tank 31 is caused by the main tank 30. The pressure changes in both tanks 30 and 31 can be measured.

The principle of the single tank system shown in FIG. 3 also applies in this case.

Therefore, when v(t) is driven at the angular frequency ωL, Δp+
When the amplitude of '(t) is measured, Δp+'(t) = Here, the amplitude of Δp+(t) when driven by ω□ is A1
, ω, and the amplitude of Δp+(t) of the cylinder driven by You are asked to do so.

I V+ = V++V2 (3d) A2 The night amount VL is determined as follows.

νL=v+V, -V, -(3e)82 In addition, when the main tank is flexible, the value C of the ratio of A, A2 is as follows.

In this case, in order to find the liquid ball, it is necessary to find 21 in AV and l kl l / by calibration. For calibration, a liquid whose volume has been correctly measured is poured into the main tank 30, and v2 and C are determined. This is done twice for different volumes, and the obtained values are substituted into equation (3f) to obtain AV, I kl I / l k21.

At this time, the liquid volume vL is determined as follows.

=VT+ AV -C-V+ (3g)
I kl + The signal processing for the rigid tank and flexible tank in the above principle explanation is as follows.

(a) In the case of a rigid tank (Fig. 6) The volume change mechanism 33 is (vosinωLt◆v(, sin
When driven by the driving force of ωHt)(ω, <ωH), the resulting pressure change is detected by the gauge pressure sensor 34, and the two parallel-connected bandpass filters 36.3
7. One bandpass filter 36 has a center angular frequency ω.

The other bandpass filter 37 is set to extract only the signal component of angular frequency ω, and the other bandpass filter 37 is set to extract only the signal component of angular frequency ω8, with center angular frequency ωH. These bandpass filters 36
．． The respective output signals of 37 are connected to each other, and the amplitudes are detected by amplitude detectors 38 and 39 having the same gain. The output γPOVO is the higher angular frequency ωH
The amplitude of the signal component of is divided by the divider 40, and the volume v2 of the cavity in the main tank 30 and the correction tank 3
The sum (V1+v2) of the volume of 1 and 1 is calculated.

The calculation results V, +V are the volume VT of the main tank 3o set in subtraction 41 and the volume v1 of the correction tank 31.
As a result, the volume of the liquid, etc., stored in the main tank 3o is calculated. Note that the gain of one bandpass filter 36 is set to 71 times the gain of the other bandpass filter 37.

(b) In the case of a flexible tank (Fig. 5) The volume change mechanism 33 is (V(ISlnωLt+Vos1nωHt)(
When driven by a driving force of ω (ωH), the resulting pressure change is detected by the gauge pressure sensor 34 and supplied to the two band-pass filters 36 and 37 described above. One band-pass filter 36 extracts a signal component with an angular frequency ω, and the other band-pass filter 37 extracts a signal component with an angular frequency ω□, and each output signal is connected to the above-mentioned amplitude The amplitudes are detected in the detectors 38 and 39, the output of the one amplitude detector 38 detecting the amplitude of the signal component of the lower angular frequency ω, γl kl I P
(, vo is the other one that detects the amplitude of the signal component of the higher angular frequency ω□.

1 to 11 The calculation result (Vpaper Δv) li + zl is amplified by an amplification factor 42 of 1 kz/+l corresponding to the correction coefficient calculated from the coefficient of the pressure transfer function. Thereafter, the amplified signal is subtracted from the value (Vl''V2+ΔV) set by the subtracter 41, and as a result, the volume VL of the liquid or other material stored in the main tank 30 is calculated. Note that AV and Ik21/Ikl+ are determined in advance through calibration.

[Effects of the Invention] As described above, the present invention allows a correction tank to be internally communicated with a main tank, and also provides a volume changing means that can vary the internal volume of the correction tank, and furthermore, the volume changing means By measuring the internal pressure inside the correction tank that occurs when the volume inside the correction tank changes due to The remaining amount of stored material can be detected very easily and accurately using pressure and electrical signals, and the weight can be reduced. Therefore, since the contents in the tank can be detected by an extremely simple and compact mechanism, there are advantages such as improved ease of detection and economical efficiency of the equipment.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the present invention, and FIG. 2 is a state in which the coefficient of the transfer function changes by 2 when the driving frequency of the volume change mechanism 33 and the volume of the contents in the tank 30 are changed in FIG. 1. FIG. 3 is a principle explanatory diagram for explaining FIG. FIG. 5 is a detailed explanatory diagram of the present invention; FIG. 6 is an explanatory diagram of other embodiments of the present invention; FIGS. 7 to 11 The figure is an explanatory diagram of a conventional example. 30... Main tank 31... Correction tank 32... Connection pipe 33... Volume change mechanism 34... Gauge pressure sensor 35... Vent hole 36.
37...Band pass filter 38.39...Amplitude detector 40...Divider 41...Subtractor 42.
...Amplifier Figure 1 Figure 2 67 - Figure Va (t) Figure size + 2b Figure 1C Figure 11 Size correction form

Claims (1)

[Claims] 1. A plurality of tanks (30, 31) are connected by a pipe (32), and one of the plurality of tanks is provided with means (33) for changing its volume, and Means (33)
is driven at the same number of frequencies as the number of tanks (30, 31), the pressure fluctuation is detected by a pressure sensor (34), and based on the detection output, at least one of the plurality of tanks is driven. A volume measurement method that calculates the volume of contents in a tank. 2 A plurality of tanks (30, 31) and the tank (30
, 31), and any one tank (3) among the plurality of tanks (30, 31).
0 or 31), and is installed in a tank equipped with the volume changing means, and detects the internal pressure of the tank (30 or 31) having at least the volume changing means. pressure sensor (34)
A volume measuring device comprising: