JP2006308565A - Apparatus and method for measuring volume - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure volume with high accuracy, even when an item to be measured, such as a liquid fuel, etc. runs short in a container, as in a relatively big tank, including a liquid fuel tank. <P>SOLUTION: An apparatus for measuring a volume includes a second container arranged in a first container, in which the thing to be measured which is, for example, liquid fuel is held, a guide means which guides the item to be measured in the second container, a resonance tube which communicates with external space from an internal space of the second container, a sound wave generating means for generating sound wave in the internal space of the second container, and a processing means for obtaining the volume of the item to be measured in the internal space of the second container. The first container has an ejection port for ejecting the item to be measured, to the outside in a part that is included in the second container. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a volume measuring apparatus that measures the volume of liquid in a closed (closed) container in space environment technology, for example, in a vacuum environment such as under zero gravity, microgravity, or in an orbit of an artificial satellite. And a method. The present invention further relates to a volume measuring apparatus and method for measuring a liquid volume under, for example, gravity or normal gravity.

  As this type of volume measuring apparatus and method, there is a Helmholtz type measurement. Conventionally, volume measurement in an “open system” container is disclosed in Patent Documents 1 and 2, for example. According to these techniques, an open resonance tube (also referred to as an “acoustic tube”) is provided in a container, and sound waves are output from a speaker or the like into the container, and the Helmholtz resonance sound is collected by a microphone. Thus, the volume of the liquid is obtained from the resonance frequency.

  On the other hand, volume measurement in a “closed system” container among Helmholtz type measurements is disclosed in Patent Documents 3 to 6, for example. In these technologies, two closed containers are connected by a resonance tube, sound waves are output from a speaker or the like into the container, and the Helmholtz resonance sound is collected by a microphone. The volume is obtained.

  Patent Document 7 discloses a liquid quantity measuring device in a tank using a superconducting speaker.

Japanese Patent Laid-Open No. 08-327429 Japanese Patent Application Laid-Open No. 07-083730 JP 2003-004503 A Japanese Patent Laid-Open No. 06-201433 Japanese Patent Laid-Open No. 06-201434 JP 2003-004503 A JP 2002-291093 A

However, in the measurement method described above, in the case of a relatively large tank that stores liquid fuel, such as thousands of liters or tens of thousands of liters, as a container in which measurement is performed, the resonance frequency to be handled is significantly reduced. It becomes difficult to adapt. In particular, in a critical situation where the remaining amount of liquid fuel is low, it is technically difficult to measure the volume of a relatively small amount of liquid with high accuracy in a relatively large tank. Challenges arise.
In addition, when utilizing the resonance phenomenon in the measurement container separately provided outside the tank, it is difficult to directly or accurately measure the volume of the liquid in the actual tank.

  The present invention has been made in view of, for example, the above-described problems. For example, in a container such as a relatively large tank such as a liquid fuel tank, even when the measurement object such as liquid fuel is reduced, the It is an object of the present invention to provide a volume measuring apparatus and method capable of performing volume measurement with high accuracy.

  In order to solve the above problems, the first volume measuring device of the present invention is provided in the first container, the second container disposed in the first container in which the object to be measured is accommodated, Guiding means for guiding the object to be measured into the second container; a resonance tube communicating from the internal space of the second container to the external space of the second container; and a sound wave generating means for generating sound waves in the internal space; Processing means for obtaining a volume of the object to be measured in the internal space based on an acoustic signal relating to the generated sound wave, and the first container is placed at a location included in the second container. A discharge port for discharging the measurement object to the outside of the first container is provided.

  According to the first volume measuring apparatus of the present invention, the object to be measured which is typically a liquid such as liquid fuel is accommodated in the first container. The first container is provided with guiding means such as baffles, harnesses, and fins, which will be described in detail later. For example, under zero gravity, microgravity, or in a vacuum environment such as on an orbit of an artificial satellite. Even if it exists, the object to be measured is guided into the second container. And the to-be-measured object is discharged | emitted outside the 1st container through the discharge port of the 1st container provided in the location contained in a 2nd container. In other words, it is possible to supply an object to be measured such as liquid fuel to the outside from, for example, a first container as a fuel tank. Here, in particular, in such a first container, the second container is arranged as a measurement container for performing volume measurement. For example, a resonance tube, which is a neck tube, is connected from the internal space of the second container to the outside. It is provided to communicate with the space. Since such a resonance tube constructs a configuration in which two containers in a closed system are connected by a resonance tube, Helmholtz-type measurement is possible. The external space communicated with the internal space of the second container by the resonance tube typically coincides with a part or all of the internal space of the first container.

  The discharge port may also serve as an inflow port for introducing liquid fuel or the like into the first container, that is, an exit / inlet. Or the inflow port for putting liquid fuel etc. in the 1st container may be provided in a different place from the discharge port in the 1st container.

  During measurement by the first volume measuring device, sound waves are generated in the internal space of the second container by the sound wave generating means. And the volume of the to-be-measured object in the internal space of a 2nd container is calculated | required by a processing means based on the acoustic signal which concerns on this generated sound wave. For example, such a volume is determined by Helmholtz type measurement in a “closed system” container. More specifically, for example, when an electrodynamic loudspeaker outputs a sound wave from its sound wave output surface, for example, sweeps a sound of a predetermined frequency band, the sound wave is generated in the internal space of the second container as a measurement container. Is output. The processing means obtains the volume of the object to be measured in the second container, for example, by closed-type Helmholtz type measurement based on the acoustic signal related to the sound wave. At this time, the second container, the resonance tube, and the outside of the second container (that is, a part of the first container) in which these measured objects are accommodated are “sealed containers”, that is, a closed system. Therefore, measurement is possible even in a high vacuum atmosphere such as outer space.

  In particular, in liquid volume measurement under zero gravity or microgravity, a liquid volume measurement method using Helmholtz resonance, that is, Helmholtz type measurement is preferable. Helmholtz type measurement is one of the volume measurement methods for liquids, solids, fluids, viscous bodies, etc. by sound waves using the volume dependence of frequency, and has the feature that it is not affected by the shape of the object to be measured. It is.

Therefore, when the volume of the object to be measured that is housed in the first container and guided into the second container is less than the volume of the second container, the volume measuring device accommodates the object to be measured in the second container. The volume of the measured object can be measured. At this time, since the size of the second container is smaller than that of the first container, the wavelength handled in the Helmholtz type measurement is compared with the case where volume measurement is performed by the same method using the first container as the measurement container. Can be shortened.
As a result, it is possible to perform measurement with higher accuracy using the relatively small second container as the measurement container. That is, even in the case of a relatively large tank for accommodating liquid fuel, such as thousands of liters or tens of thousands of liters, it is possible to avoid a situation in which the resonance frequency handled when performing Helmholtz type measurement is significantly reduced. In other words, it is not necessary to use a large wavelength that is necessary when the measurement is performed by providing a resonance tube in a first container such as a large tank as the wavelength of the sound wave when resonating.

  In this way, the volume of a relatively small amount of liquid remaining in a relatively large tank can be measured with high accuracy. This is very advantageous in practice. Incidentally, if a Helmholtz type measurement is performed in a first container such as a relatively large tank, the capacity of the tank or the like is limited to about 1 cubic meter in a practical sense.

  In addition, the liquid volume in the first container such as an actual tank is directly measured in the vicinity of the discharge port as compared to using the resonance phenomenon in a measurement container separately provided outside the tank. Therefore, it is essentially easy to measure accurately. Furthermore, according to the present invention, it is possible to save space as compared with the case where the measurement container is separately provided outside the first container.

  In particular, since the size of the second container can be arbitrarily reduced, it corresponds to the volume range to be measured as much as possible in view of the actual use environment, the purpose of use, and the attributes of the measurement object such as liquid fuel to be measured. Thus, the size of the second container may be set so that a resonance wavelength with as high a measurement accuracy as possible can be obtained. In general, the Helmholtz resonance phenomenon has a drawback in that the amount of change in frequency with respect to the change in the liquid volume when the liquid volume is low is small. The present invention is extremely excellent.

  As a result of the above, according to the first volume measuring apparatus, even in a closed system container such as a relatively large tank such as a liquid fuel tank, even when the amount of objects to be measured such as liquid fuel is reduced, Volume measurement is possible.

  In addition, when performing volume measurement in the second container with high accuracy in this way, as long as the second container is fully filled with the object to be measured, the volume of the object to be measured accommodated in the first container. This situation is far from a critical situation where liquid fuel is running low. Therefore, in such a situation, it is sufficient to perform measurement with relatively low accuracy by using various existing measurement methods such as using light attenuation. Furthermore, when the second container is filled with the object to be measured, the measurement is selectively performed by another volume measuring device different from the volume measuring device, and the second container is measured. A combination in which measurement is selectively performed by the volume measuring device when it is not fully filled with an object is also one aspect of the first volume measuring device of the present invention.

  As described above, according to the first volume measuring apparatus, for example, storage or storage of cryogenic propellants such as liquid oxygen, liquid hydrogen, and liquefied methane (liquefied natural gas) in outer space, particularly in the earth or planetary orbit, in orbit. It is possible to measure the amount of liquid under weightlessness or microgravity, which is important during transfer. In addition, the present invention makes it possible to perform highly accurate measurement in a situation where accuracy is truly required, such as when the amount of objects to be measured such as fuel has been reduced. This is very useful for transporting, storing and resupplying fuel in outer space, and for supplying it to an interorbit space transport aircraft OTV (Orbit Transfer Vehicle).

  In one aspect of the first volume measuring apparatus of the present invention, the guiding means extends toward the second container in the first container, and guides the object to be measured in a weightless or microgravity state. Comprising at least one baffle.

  According to this aspect, it decreases as it is discharged from the discharge port by the guide means including one or a plurality of baffles that guides the object to be measured in a zero gravity or microgravity state in the first container. It becomes possible to always guide the object to be measured into the second container. Here, the “baffle” according to the present invention is a plate-like member or baffle plate that defines or regulates the flow path of an object to be measured such as a liquid, and extends from the inner wall of the first container to the inner side of the first container. This means that the object to be measured can be guided by the surface tension of the object to be measured. Here, in particular, since the baffle erected toward the inside of the first container extends toward the second container, the object to be measured accommodated in the first container It will act to guide into the two containers.

  As a result, the object to be measured is guided into the second container by the baffle and discharged through the discharge port, and the measurement of the volume of the object to be measured whose volume decreases with this is achieved with high accuracy by the present invention described above. Will be done.

  In addition, the guiding means replaces the baffle with a belt-like member extending toward the second container in the same manner as the baffle, such as 90 degrees, and the inner angle is a predetermined angle with the center line along the extending direction as the center. The harness created by bending toward the inner side of the first container may be included. Or it may replace with a baffle and may include the fin which protrudes toward the 2nd container like the baffle and protrudes to the inner side of the 1st container. In any case of the baffle, the harness, and the fin, the object to be measured can be guided in a weightless or microgravity state by using the surface tension.

  In another aspect of the first volume measuring apparatus of the present invention, the device to be measured, which is provided in the second container and is guided into the second container by the guiding means, is guided to the discharge port. And further guiding means.

  According to this aspect, since the object to be measured after being guided into the second container can be further guided to the discharge port by the other guiding means, the object to be measured is completely discharged through the discharge port. While enabling discharge, Helmholtz type volume measurement in the second container can be performed with high accuracy.

  Note that other guiding means provided in the second container may include baffles, harnesses, fins, and the like, similar to the guiding means provided in the first container.

  In order to solve the above-mentioned problem, the second volume measuring device of the present invention includes a second container disposed on the vertically lower side in the first container in which the object to be measured is accommodated, and an internal space of the second container. Based on a resonance tube communicating with the external space of the second container, sound wave generating means for generating sound waves in the internal space, and an acoustic signal relating to the generated sound waves, the volume of the object to be measured in the internal space The first container has a discharge port for discharging the object to be measured to the outside of the first container at a location included in the second container.

  According to the second volume measuring apparatus of the present invention, the object to be measured which is typically a liquid such as liquid fuel is accommodated in the first container. And after a to-be-measured object is guide | induced by gravity to the 2nd container arrange | positioned at the vertically downward side in a 1st container, it passes through the discharge port of the 1st container provided in the location contained in a 2nd container. , And discharged outside the first container. In other words, it is possible to supply an object to be measured such as liquid fuel to the outside using gravity. Here, in particular, in such a first container, the second container is arranged as a measurement container for performing volume measurement. For example, a resonance tube, which is a neck tube, is connected from the internal space of the second container to the outside. It is provided to communicate with the space. Since such a resonance tube constructs a configuration in which two containers in a closed system are connected by a resonance tube, Helmholtz-type measurement is possible.

  At the time of measurement by the second volume measuring device, sound waves are generated in the internal space of the second container by the sound wave generating means, as in the case of the first volume measuring device according to the present invention described above. And the volume of the to-be-measured object in the internal space of a 2nd container is calculated | required by a processing means based on the acoustic signal which concerns on this generated sound wave. Accordingly, when the volume of the object to be measured, which is contained in the first container and is induced by gravity, falls below the volume of the second container, the object to be contained in the second container. The volume of the measurement object can be measured with high accuracy.

  As a result of the above, according to the present invention, it is possible to measure the volume with high accuracy even in the case where the object to be measured such as liquid fuel is reduced in a relatively large tank such as a liquid fuel tank. .

  In addition, when the second container is fully filled with the object to be measured, relatively low-precision measurement is selectively performed by various existing volume measuring apparatuses different from the volume measuring apparatus, and the second container A combination in which measurement with a relatively high accuracy is selectively performed by the volume measuring device when the container is not fully filled with the object to be measured is also an aspect of the second volume measuring device of the present invention. is there.

  In another aspect of the first or second volume measuring device of the present invention, the sound wave generating means includes an electrodynamic speaker in which a sound wave output surface is disposed opposite to a wall of the second container, The processing means includes measurement means for measuring the voltage of the voice coil related to the electrodynamic speaker, and calculation means for calculating the volume of the device under test based on the measured voltage.

  According to this aspect, for example, the voltage of the voice coil related to the electrodynamic speaker is measured by the measurement unit while the electrodynamic speaker is driven at a constant current by the amplifier. Here, since the voltage of the voice coil is substantially proportional to the impedance of the voice coil, the volume of the object to be measured can be calculated by the calculation means based on the voltage of the voice coil. That is, as the acoustic signal used for measurement by the processing means, the “acoustic signal related to the sound wave output into the sealed space” is indirectly measured by measuring a voltage substantially proportional to the impedance of the voice coil of the electrodynamic speaker. Can be obtained. Therefore, the Helmholtz resonance frequency for the gas phase portion in the second container can be specified or identified.

  In addition, the electrodynamic speaker is driven at a constant voltage instead of being driven at a constant current, so that the anti-resonance frequency of the impedance curve relating to the voice coil of the electrodynamic speaker is specified or identified, and the volume is increased by this anti-resonance frequency. It is also possible to measure.

  In order to solve the above-mentioned problem, the first volume measuring method of the present invention is provided in the first container, the second container disposed in the first container in which the object to be measured is accommodated, Introducing means for guiding an object to be measured into the second container, and a resonance tube communicating from the internal space of the second container to the external space of the second container, the first container being the second container A volume measuring method in a volume measuring device having a discharge port for discharging the object to be measured to the outside of the first container at a location included therein, a sound wave generating step for generating sound waves in the internal space; And a processing step of obtaining a volume of the object to be measured in the internal space based on an acoustic signal relating to the generated sound wave.

  According to the first volume measuring method of the present invention, as in the case of the above-described first volume measuring device of the present invention, for example, by the Helmholtz type measurement in a closed system, the object to be measured under zero gravity or microgravity can be obtained. The volume can be determined relatively easily and with high accuracy.

In order to solve the above-mentioned problem, the second volume measuring method of the present invention includes a second container arranged on the vertically lower side in the first container in which the object to be measured is accommodated, and an internal space of the second container. A resonance tube communicating with the external space of the second container, and the first container has an outlet for discharging the object to be measured to the outside of the first container at a location included in the second container A volume measuring method in a volume measuring device having a sound wave generating step for generating sound waves in the internal space;
And a processing step of obtaining a volume of the object to be measured in the internal space based on an acoustic signal relating to the generated sound wave.

  According to the second volume measuring method of the present invention, as in the case of the above-described second volume measuring device of the present invention, for example, under a Helmholtz type measurement in a closed system or an open system, under gravity or under normal gravity. The volume of the object to be measured can be determined relatively easily and with high accuracy.

  In the first or second volume measuring method, various aspects corresponding to the various aspects of the first or second volume measuring apparatus can be employed.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A first embodiment of the volume measuring apparatus of the present invention will be described with reference to FIGS. The first embodiment is an embodiment of a first volume measuring apparatus according to the present invention.

  First, the principle of volume measurement according to the first embodiment will be described with reference to FIG. This principle is common to the second embodiment described later. FIG. 1 is a schematic conceptual diagram for explaining such a principle by taking a liquid volume measurement as an example.

In FIG. 1, a space that can store a liquid constructed in a tank as an example of a “first container” according to the present invention to be described later is a closed system space, and has a volume V ₁ and a pressure p _1. 1 and a second space 2 having a volume V ₂ and a pressure p ₂ . The first space 1 and the second space 2 are connected to each other by a resonance tube 3.

  Note that the internal space of the measurement container, which is an example of a “second container” according to the present invention described later, coincides with the second space 2, and the first space constituting the measurement container among the internal spaces of the tank described later. The space part excluding the space part 1 is the second space 2.

  The state of FIG. 1 shows a liquid phase / gas phase state in which volume measurement according to the present invention is effective. The first space 1 is occupied by the gas phase portion 30 and the second space 2 is The gas phase part 30 and the liquid phase part 40 are mixed. In the present embodiment, in particular, the separation of the gas phase portion 30 and the liquid phase portion 40 is performed by “guidance means” described later. Thereby, the measurement of the volume of the liquid phase part 40 by sound under microgravity is made possible as described below.

  For the sake of simplification, assuming an isothermal change and non-compression, and not considering nozzle part correction, the equation of motion is as follows.

ここで、変動圧力ｐ_１及びｐ_２は夫々、次の式（２）及び（３）と表すことができる。

Here, the fluctuating pressures p ₁ and p ₂ can be expressed by the following equations (2) and (3), respectively.

但し、γは比熱比、Ｐ_０は基準圧力、Ｌは共鳴管３の長さ、Ａは共鳴管３の断面積、ｕは速度、Ｖ_１及びＶ_２は第１空間１及び第２空間２の気相部３０の体積を夫々表す。これら圧力変動を計測することにより、体積Ｖ_１及びＶ_２を夫々求めることができる。

Where γ is the specific heat ratio, P ₀ is the reference pressure, L is the length of the resonance tube 3, A is the cross-sectional area of the resonance tube 3, u is the velocity, V ₁ and V ₂ are the first space 1 and the second space 2. Represents the volume of each gas phase part 30. By measuring these pressure fluctuations, the volumes V ₁ and V ₂ can be determined respectively.

  Next, the following formula (4) can be derived by substituting the formulas (2) and (3) into the formula (1).

ここで、ｕ＝Ｕｅ^ｉωｔとし、これを式（４）に代入すると、角速度ωについて以下の式（５）を導くことができる。

Here, when u = Ue ^iωt and this is substituted into the equation (4), the following equation (5) can be derived for the angular velocity ω.

ここで、音速Ｃは、

Here, the speed of sound C is

であるので、この場合のヘルムホルツ共鳴周波数ｆは、以下の式（６）のようになる。

Therefore, the Helmholtz resonance frequency f in this case is expressed by the following equation (6).

ここで、２πは定数であり、共鳴管３の断面積Ａ、共鳴管３の長さＬ及び容器１の気相部の体積Ｖ_１は既知の値である。音速Ｃは温度と圧力から求めることができる。よって、体積Ｖ_２の変化量が周波数ｆの変化として現れることから、この周波数を解析することにより第２空間２の液体量を求めることが可能となる。その際、微小重力下においては気相部３０及び液相部４０が混在することから、第１空間１や第２空間２内に、例えば、後述するバッフル等からなる表面張力を利用しての気液相分離機能を有する「誘導手段」を設置することにより、初めて微小重力下での音響による液体の体積計測が実用化できる。

Here, 2π is a constant, and the cross-sectional area A of the resonance tube 3, the length L of the resonance tube 3, and the volume V1 of the gas phase part of the container ₁ are known values. The speed of sound C can be obtained from temperature and pressure. Therefore, since the change amount of the volume V ₂ appears as a change of the frequency f, it is possible to obtain the liquid amount of the second space 2 by analyzing this frequency. At that time, since the gas phase part 30 and the liquid phase part 40 coexist under microgravity, the surface tension formed by, for example, a baffle described later is used in the first space 1 or the second space 2. By installing “guidance means” having a gas-liquid phase separation function, it is possible to practically measure the volume of a liquid by sound under microgravity for the first time.

  FIG. 1 schematically shows an installation position of an electrodynamic speaker 101 to be described in detail below, which enables measurement based on such a principle.

  A specific configuration and measurement operation of the volume measuring apparatus according to the first embodiment based on the measurement principle described above will be described with reference to FIGS. FIG. 2 is a schematic cross-sectional view showing the entire volume measuring apparatus including a tank for storing a liquid to be measured and a measuring device, and FIG. 3 is a plan view of the tank portion. 4 is a partially broken perspective view of the tank portion.

  As shown in FIGS. 2 to 4, the volume measuring apparatus according to this embodiment includes a tank 10, a measurement container 20, a resonance tube 3, a liquid inlet / outlet 50, a large baffle 51, a small baffle 52, and a liquid inlet 53. Prepare.

  The tank 10 constitutes an example of a “first container” according to the present invention, and includes a large tank that stores a liquid such as liquid fuel as an example of the “measurement object” according to the present invention. In FIG. 2, the liquid is taken in and out through the liquid inlet / outlet 50 provided at the lowermost end. For example, when refueling, liquid fuel is replenished into the tank 10 from the outside via the liquid inlet / outlet 50, and liquid fuel is supplied from the tank 10 to the outside via the liquid inlet / outlet 50 during fuel supply. In addition, the liquid inlet / outlet port 50 provided in the measurement container 20 may be dedicated to the outlet, and separately from this, the liquid inlet may be provided at an arbitrary location of the tank 10.

  The measurement container 20 constitutes an example of a “second container” according to the present invention, and is disposed in the tank 10. The space excluding the measurement container 20 in the large tank 10 corresponds to the first space 1 shown in FIG. 1, and the space in the measurement container 20 corresponds to the first space 1 shown in FIG. ing. The two spaces communicate with each other via a resonance tube 3 that is a neck tube, for example.

  The large baffles 51 constitute an example of the “guidance means” according to the present invention. In the present embodiment, four large baffles 51 are provided on the inner wall of the tank 10 so as to extend in the vertical direction in FIG. . The large baffle 51 guides the liquid in the tank 10 into the measurement container 10 through the liquid intake 53 using the surface tension of the liquid. In other words, the large baffle 51 can guide liquid into the measurement container 20 by surface tension even under a zero-gravity, microgravity, or vacuum environment such as on an orbit of an artificial satellite. . Thereby, as shown in FIG. 1, the vapor phase portion 30 and the liquid phase portion 40 are separated, and the liquid in the tank 10 is moved into the measurement container 20 (further, via the liquid inlet / outlet 50, the tank 10. Configured to guide out). The specific configuration of the large baffle 51 will be described later (see FIG. 5).

  The small baffle 52 constitutes an example of “another guiding means” according to the present invention. In this embodiment, four small baffles 52 are provided on the inner wall of the measurement container 20 so as to extend in the vertical direction in FIG. Is provided. The small baffle 52 guides the liquid in the measurement container 20 to the liquid inlet / outlet 50 using surface tension. That is, the small baffle 52 allows the liquid to enter and exit the liquid inlet / outlet 50 in the measuring container 20 due to surface tension even under a zero gravity, microgravity, or a vacuum environment such as on the orbit of an artificial satellite. Can be guided to. Thereby, as shown in FIG. 1, the gas phase part 30 and the liquid phase part 40 are separated, and the liquid in the tank 10 is guided to the outside of the tank through the liquid inlet / outlet 50.

  As shown in FIG. 3, the four large baffles 51 are provided at intervals of approximately 90 degrees with the liquid inlet / outlet 50 as the center, and the four small baffles 52 are approximately 90 degrees with the liquid inlet / outlet 50 as the center. It is provided at intervals. Further, the large baffle 51 and the small baffle 52 are attached at different azimuth angles around the liquid inlet / outlet port 50 so that the attachment positions do not overlap each other in the circumferential direction. The four liquid inlets 53 are provided at the same azimuth angle as the large baffle 51 around the liquid inlet / outlet 50 so that the liquid guided by the large baffle 51 can be taken in. The liquid inlet / outlet port 50 is formed by opening a part of the wall of the measurement container 20 so that the liquid guided by the large baffle 51 can be taken into the measurement container 20.

  As shown in FIG. 2, the volume measuring apparatus according to the present embodiment further includes an electrodynamic speaker 101 that generates sound waves in the second space 2 of the measurement container 20, and an acoustic signal related to the sound waves generated thereby. , A driving amplifier 102, a measurement amplifier 103, a transmission / reception controller 104, and an arithmetic unit that constitute an example of the “processing means” according to the present invention for obtaining the volume of the liquid existing in the second space 2 105.

  Next, a further detailed configuration of the volume measuring apparatus configured as described above will be described together with the measuring operation.

  At the time of measurement, the electrodynamic speaker 101 is driven by the driving amplifier 102 under the control of the transmission / reception controller 104 including a CPU, a system controller, a memory, and the like, so that the second space 2 as the internal space of the measurement container 20 is obtained. To generate sound waves. Then, under the control of the transmission / reception controller 104, the measurement amplifier 103 amplifies the acoustic signal related to the sound wave generated by the electrodynamic speaker 101, and further, under the control of the transmission / reception controller 104, the CPU, Based on this acoustic signal, the volume of the liquid in the second space 2 is obtained by a computing unit 105 including a system controller and a memory. Here, such a volume is obtained by Helmholtz type measurement in the “closed system” container described with reference to FIG.

  More specifically, at the time of measurement, the signal time is several tens of milliseconds to several seconds by the transmission / reception controller 104, and the first space 1, the resonance tube 3 and the measurement tube constructed in the tank 10 are used. When the second space 2 (see FIG. 1) in the container 20 is viewed as a “resonator”, a sweep wave in a band including the Helmholtz resonance frequency is output. At this time, the electrodynamic speaker 101 is driven with a constant current by using the driving amplifier 102.

  If the response of the “resonator” is detected by a microphone, external noise other than an acoustic signal is superimposed by the microphone, particularly when the volume is reduced to suppress heat generation by the electrodynamic speaker 101. Will be detected. Therefore, ultimately, the identification accuracy of the Helmholtz resonance frequency is lowered.

  However, in this embodiment, the driving amplifier 102 drives the electrodynamic speaker 101 with a constant current, and the voice coil voltage of the electrodynamic speaker 101 is transmitted to the transmission / reception controller 104 via the measurement amplifier 103. Receive. At this time, the volume is not reduced in order to suppress heat generation by the electrodynamic speaker 101.

  Subsequently, the arithmetic unit 105 receives the voltage signal related to the voice coil voltage corresponding to the acoustic signal in this way from the transmission / reception controller 104, and calculates the power spectrum using the maximum entropy (MEM) method. Subsequently, the dominant frequency peak is determined. At this time, the computing unit 104 can identify the peak frequency on the power spectrum with a frequency resolution of 1 Hz or less even if the signal time is as short as several seconds or less by using the MEM method. Subsequently, the frequency that gives this peak is substituted as the Helmholtz resonance frequency, for example, in the above-described equation (6), and the volume of the gas phase portion occupying the second space 2 of the measurement container 20 is determined. That is, the volume V2 of the gas phase portion in the measurement container 20 can be calculated by analyzing the frequency f. Since the total volume of the measurement container 20 is known (fixed value), the volume of the liquid stored in the measurement container 20 can be calculated after all.

  The volume value measured as a result of the above is displayed on, for example, a display panel (not shown) or recorded in a form associated with the type of liquid and time on a recording device such as a recorder.

  As described above, according to the first embodiment, the Helmholtz frequencies obtained by resonance are obtained in advance for each volume of the liquid stored in the measurement container 20, and these values are tabulated. Alternatively, if the relationship between each volume and the Helmholtz resonance frequency is approximated by a predetermined function, the actual measurement will be performed later from the Helmholtz resonance frequency obtained by measuring the voltage of the voice coil of the electrodynamic speaker 101. The volume of the liquid accommodated in the measurement container 20 can be uniquely specified.

  In the case of such measurement, the tank 10 including the resonance tube 3 and the measurement container 20 is a “sealed container”, that is, a closed system. Therefore, even in a high vacuum atmosphere such as outer space, Measurement is possible.

  Accordingly, when the volume of the liquid contained in the tank 10 and guided into the measurement container 20 by the large baffle 51 falls below the volume of the measurement container 20, the measurement container 20 is used by the volume measuring device. The volume of the liquid accommodated in the inside can be measured. At this time, even if the tank 10 is huge, for example, thousands of liters or tens of thousands of liters, the wavelength of the sound wave for performing Helmholtz-type measurement to be emitted from the electrodynamic speaker 101 is the same as that of the measurement container 20. A thing suitable for the size is sufficient. Here, the volume of the small amount of liquid remaining in the tank 10 can be obtained by setting the size of the measurement container 20 so as to obtain a resonance wavelength that preferably increases the measurement accuracy in the volume range to be measured. Can be measured with extremely high accuracy.

  As a result of the above, according to the present embodiment, it is possible to measure the volume with high accuracy even under the condition of zero gravity, microgravity, or when the liquid such as liquid fuel remains in the tank 10. Further, when the measurement container 20 is filled with the liquid, it may be separately measured by using various existing measurement methods such as light attenuation.

  In the above-described embodiment, a configuration in which no microphone is installed in the measurement container 20 is employed. In the case of a microphone, S / N ratio may decrease as a result of superimposing external noise on an acoustic signal. Therefore, measurement without using the microphone is advantageous from the viewpoint of improving measurement accuracy. However, a microphone may be arranged in the measurement container 20 and the volume of the liquid in the measurement container 20 may be obtained based on the acoustic signal related to the sound wave received thereby. In this case, when sound waves are output from the electrodynamic loudspeaker 101 during measurement, the sound waves are output into the measurement container 20, and the sound waves are received by the microphone. Based on the acoustic signals related to the received sound waves. For example, the volume of the liquid is obtained by Helmholtz type measurement.

  Furthermore, in the above-described embodiment, the electrodynamic speaker 101 is driven at a constant current, but by driving this at a constant voltage, the anti-resonance frequency of the impedance curve related to the voice coil of the electrodynamic speaker 101 can be specified or It is also possible to identify and measure the volume by this anti-resonance frequency.

  Next, with reference to FIG.4 and FIG.5, the detailed structure of the large baffle 51 as an example of the guidance means which concerns on this invention is demonstrated. FIG. 5 is an enlarged perspective view of one baffle used in the present embodiment shown in FIG.

  As shown in FIGS. 4 and 5, the large baffle 51, as an example of the “guidance means” according to the present invention, extends from the portion facing the liquid inlet / outlet 50 toward the liquid inlet / outlet 50 in the tank 10. The liquid contained in the tank 10 is guided in a weightless or microgravity state. The large baffle 51 is a plate-like member or baffle plate that defines or regulates the liquid flow path in the tank 10. And it is erected on the inner wall of the tank 10 toward the inner side of the tank 10. The material, surface state, width, thickness, etc. of the large baffle 51 are experimental and empirical so that induction by surface tension is efficiently performed according to the attributes of the liquid to be handled and the usage environment of the volume measuring device. Determined by simulation or the like. Here, the width of the portion facing the liquid inlet / outlet 50 is relatively wide, and the width of the portion close to the liquid inlet / outlet 50 is relatively narrow.

  In the present embodiment, only four large baffles 51 configured as described above are used as already shown in FIGS. 2 to 4, but less than four large baffles 51 may be used. More than one may be used.

  In addition, although the small baffle 52 provided in the measurement container 20 according to the present embodiment shown in FIGS. 2 to 4 is small according to the size of the measurement container 20, the same principle as the large baffle 51 is used. And has a shape for guiding the liquid. The material, surface state, width, thickness, etc. of the small baffle 52 are also experimental and empirical so that the induction by the surface tension is efficiently performed according to the attribute of the liquid to be handled and the usage environment of the volume measuring device. It is determined by simulation or the like.

(Deformation)
A modification of the first embodiment will be described with reference to FIGS. 6 and 7 are perspective views having the same concept as in FIG. 5 in the modified embodiment.

  In the first embodiment described above, the large baffle 51 and the small baffle 52 constitute one example of “guidance means” and “other guidance means” according to the present invention, respectively. Instead of at least one of the above, a harness or a fin can be used.

  That is, as illustrated in FIG. 6, in one modification, a harness 251 is provided instead of the large baffle 51. The small baffle 52 may be the same as that in the first embodiment or may be replaced with a harness. About another structure, it is the same as that of 1st Embodiment.

  As another example of the “guidance means” according to the present invention, the harness 251 includes, in the tank 10, a band-like member extending from the portion facing the liquid inlet / outlet 50 toward the liquid inlet / outlet 50 in the extending direction. It is created by bending toward the inner side of the tank 10 so that the inner angle becomes about 90 degrees with the center line along the center. The material, surface state, width, thickness, bending angle, etc. of the harness 251 are experimental so that the induction by the surface tension is efficiently performed according to the attribute of the liquid to be handled and the usage environment of the volume measuring device. Determined empirically and by simulation. Here, the width and thickness in the extending direction are configured uniformly. Such a harness 251 can also guide the liquid into the measurement container 20 by the surface tension of the liquid stored in the tank 10.

  Further, as illustrated in FIG. 7, in another modification, a fin 351 is provided instead of the large baffle 51. The small baffle 52 may be the same as in the first embodiment or may be replaced with fins. About another structure, it is the same as that of 1st Embodiment.

As another example of the “guidance means” according to the present invention, the fin 351 extends from the portion facing the liquid inlet / outlet 50 toward the liquid inlet / outlet 50 and protrudes toward the inside of the tank 10 in the tank 10. Created from a bar-shaped member. The material, surface state, width, thickness, etc. of the fin 351 are experimental, empirical, and simulation so that induction by surface tension is efficiently performed according to the attribute of the liquid to be handled and the usage environment of the volume measuring device. Etc. are determined.
Here, the width and thickness in the extending direction are configured uniformly. Also with such fins 351, the liquid can be guided into the measurement container 20 by the surface tension of the liquid stored in the tank 10.

(Second Embodiment)
A second embodiment of the volume measuring device will be described with reference to FIG. The volume measuring device of the second embodiment is an embodiment of the “second volume measuring device” according to the present invention, and is a Helmholtz type measuring device under gravity. FIG. 8 is a drawing having the same concept as in FIG. 2 according to the first embodiment, and is a schematic cross section showing the entire volume measuring device including a tank for storing a liquid as a measurement object and a measuring device. FIG. In FIG. 8, the same components as those in the first embodiment shown in FIGS. 1 to 7 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  As shown in FIG. 8, the volume measuring device according to the second embodiment is configured without a guiding means such as a baffle as compared with the first embodiment shown in FIGS. 1 to 5. The liquid inlet / outlet port 50 is different from the tank 101 and the second space 2 in the vertical direction Dg, and the other configurations are basically the same as those in the first embodiment. It is.

  Under gravity, the liquid in the tank 10 can be guided into the measurement container 20 by gravity without using a guiding means such as a baffle. Therefore, it is possible to measure the volume of the liquid in the measurement container 20 by using the same measurement principle as that of the first embodiment (see FIG. 1 and the like) without guiding means.

  As a result, according to the present embodiment, even when a liquid such as liquid fuel remains in the large tank 10 under gravity, the volume can be measured with high accuracy. In addition, when the measurement container 20 is filled with the liquid, it may be separately measured by using other existing measurement methods.

(Third embodiment)
A third embodiment of the volume measuring apparatus will be described with reference to FIGS. The volume measuring apparatus according to the third embodiment is another embodiment of the “first volume measuring apparatus” according to the present invention. FIG. 9 is a drawing having the same concept as in FIG. 2 according to the first embodiment, and is a schematic cross section showing the entire volume measuring device including a tank for storing a liquid as a measurement object and a measuring device. FIG. 10 is a plan view of the tank portion, and FIG. 11 is a partially cutaway perspective view of the tank portion. 9 to 11, the same reference numerals are given to the same components as those in the first embodiment shown in FIGS. 1 to 7, and description thereof will be omitted as appropriate.

  As shown in FIGS. 9 to 11, the volume measuring apparatus according to the third embodiment has a resonance container 25 on the distal end side of the resonance tube 3 as compared with the first embodiment shown in FIGS. 1 to 5. In addition, the electrodynamic type speaker 101 is provided in the resonance container 25, and the resonance container 25, not the tank 10, constitutes the “first container” for resonance according to the present invention. Furthermore, the point which has the groove | channel 55 in the inner wall of the resonance container 25 and the resonance tube 3 differs. Other configurations and operation principles are basically the same as those in the first embodiment.

That is, in FIGS. 9 to 11, the volume measuring device according to the present embodiment includes a tank 10, a measurement container 20, a resonance tube 3, a liquid inlet / outlet 50, a large baffle 51, a small baffle 52, and a liquid inlet 53. , A resonance container 25 defining a first space having a volume V ₁ and a pressure p ₁ therein, an electrodynamic speaker 101 arranged in the resonance container 25, and a groove 55 arranged on the inner wall of the resonance tube 3. With.

In this case, the measurement container 20 constitutes an example of a “second container” according to the present invention, in which a second space having a volume V ₂ and a pressure p ₂ is defined. It is arrange | positioned in the large sized tank 10 which accommodates liquids, such as liquid fuel. The resonance container 25 constitutes an example of the “first container” according to the present invention, and includes a resonance space defined inside the measurement container 20 and a resonance space defined inside the resonance container 25. These two spaces communicate with each other via a resonance tube 3 which is a neck tube, for example.

  In FIG. 9, the liquid fuel is replenished into the tank 10 from the outside through the liquid inlet / outlet 50 located at the lowermost end, and the liquid fuel is supplied from the tank 10 to the outside through the liquid inlet / outlet 50 when refueling.

  The large baffles 51 constitute an example of the “guidance means” according to the present invention. In the present embodiment, four large baffles 51 are provided on the inner wall of the tank 10 so as to extend in the vertical direction in the drawing. The large baffle 51 guides the liquid in the tank 10 into the measurement container 20 through the liquid intake 53 using the surface tension of the liquid.

  The small baffle 52 constitutes an example of “another guiding means” according to the present invention. In the present embodiment, four small baffles 52 are provided on the inner wall of the measurement container 20 so as to extend vertically in the drawing. ing. The small baffle 52 guides the liquid in the measurement container 20 to the liquid inlet / outlet 50 using surface tension.

  Particularly in the present embodiment, the groove 55 constitutes an example of “another guiding means” according to the present invention, and is disposed on the inner wall of the resonance vessel 25 and the resonance tube 3. The groove 55 guides the liquid in the resonance container 25 to the measurement container 20 by surface tension. When the liquid volume in the tank 10 is less than or equal to the volume of the measurement container 20, the resonance space 25 and the resonance tube 3 are occupied by the gas phase by the groove 55.

  Since it is configured as described above, at the time of volume measurement, a sound wave is generated in the resonance container 25 by the electrodynamic loudspeaker 101. The driving amplifier 102, the measurement amplifier 103, the transmission / reception controller 104, and the arithmetic unit 105, which constitute an example, are defined by the measurement container 20 in the same manner as in the first embodiment. The volume of the liquid existing in the second space can be obtained.

  As described above, according to the present embodiment, the volume is obtained by Helmholtz-type measurement in the “closed system” container described with reference to FIG. 1, so that the liquid amount is less than the volume of the measurement container 20. It is possible to accurately grasp the remaining amount of liquid.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. And methods are also within the scope of the present invention.

It is a schematic conceptual diagram explaining the measurement principle in the volume measuring apparatus according to the first embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing an entire volume measuring apparatus according to a first embodiment, including a tank for storing a liquid to be measured and a measuring device. FIG. 3 is a plan view of a tank portion in FIG. 2. FIG. 3 is a partially broken perspective view of a tank portion in FIG. 2. It is a perspective view which expands and shows one baffle used for this embodiment shown by FIG. It is a perspective view of the same meaning as FIG. 5 in one modification. It is a perspective view of the same meaning as FIG. 5 in another modification. FIG. 6 is a schematic cross-sectional view showing the entire volume measuring apparatus according to the second embodiment, including a tank for storing a liquid to be measured and a measuring device. FIG. 10 is a schematic cross-sectional view showing the entire volume measuring apparatus according to the third embodiment, including a tank for storing a liquid to be measured and a measuring device. FIG. 10 is a plan view of a tank portion in FIG. 9. FIG. 10 is a partially broken perspective view of a tank portion in FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st space 2 ... 2nd space 3 ... Resonance tube 10 ... Tank 20 ... Measurement container 30 ... Gas phase part 40 ... Liquid phase part 50 ... Liquid inlet / outlet 51 ... Large baffle 52 ... Small baffle 53 ... Liquid inlet 101 ... Electrodynamic type speakers,
102 ... Drive amplifier 103 ... Measurement amplifier 104 ... Transmission / reception controller 105 ... Calculator

Claims (7)

A second container disposed in the first container in which the object to be measured is stored;
Guidance means provided in the first container and guiding the object to be measured into the second container;
A resonance tube communicating from the internal space of the second container to the external space of the second container;
Sound wave generating means for generating sound waves in the internal space;
Processing means for obtaining a volume of the object to be measured in the internal space based on an acoustic signal relating to the generated sound wave, and
The first container has a discharge port for discharging the object to be measured to the outside of the first container at a location included in the second container.   The guiding means includes at least one baffle extending toward the second container in the first container and guiding the object to be measured in a weightless or microgravity state. The volume measuring apparatus according to claim 1.   The apparatus further comprises other guiding means that is provided in the second container and guides the object to be measured guided into the second container by the guiding means to the discharge port. Item 3. The volume measuring device according to Item 1 or 2. A second container disposed on the vertically lower side in the first container in which the object to be measured is accommodated;
A resonance tube communicating from the internal space of the second container to the external space of the second container;
Sound wave generating means for generating sound waves in the internal space;
Processing means for obtaining a volume of the object to be measured in the internal space based on an acoustic signal relating to the generated sound wave, and
The first container has a discharge port for discharging the object to be measured to the outside of the first container at a location included in the second container. The sound wave generating means includes an electrodynamic speaker in which a sound wave output surface is disposed to face the wall of the second container,
The processing means includes measurement means for measuring a voltage of a voice coil related to the electrodynamic speaker, and calculation means for calculating the volume of the object to be measured based on the measured voltage. Item 5. The volume measuring device according to any one of Items 1 to 4. A second container disposed in the first container in which the object to be measured is accommodated, guidance means provided in the first container, for guiding the object to be measured into the second container; A resonance tube communicating from the internal space of the two containers to the external space of the second container, wherein the first container places the object to be measured outside the first container at a location included in the second container. A volume measuring method in a volume measuring device having a discharge port for discharging,
A sound wave generating step for generating sound waves in the internal space;
And a processing step of obtaining a volume of the object to be measured in the internal space based on an acoustic signal relating to the generated sound wave. A second container disposed vertically below the first container in which the object to be measured is accommodated, and a resonance tube communicating from the internal space of the second container to the external space of the second container, One container is a volume measuring method in a volume measuring apparatus having a discharge port for discharging the object to be measured to the outside of the first container at a location included in the second container,
A sound wave generating step for generating sound waves in the internal space;
And a processing step of obtaining a volume of the object to be measured in the internal space based on an acoustic signal relating to the generated sound wave.

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