JPH11281428A - Method and device for ultrasonic flow velocity measuring, ultrasonic flow rate measuring device and ultrasonic electronic ags meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for ultrasonic flow velocity measuring capable of measuring a flow velocity neglecting a flow velocity change caused of a pulsating flow, a flow rate measuring device and an ultrasonic electronic gas meter. SOLUTION: In a main flow path 2a where fluid flows, by first acoustic means TD11 and TD12, a first time t1 for the propagation of an ultrasonic wave within a first specified distance L1 in the main flow path is measured. In a sub-flow path 2b constructed in such a manner that both ends thereof are communicated with the upstream and downstream sides of the main flow path, but no fluid is allowed to flow therein, and the pressure change of the upstream and downstream sides of the main flow path is transmitted to both ends thereof, by second acoustic means TD13 and TD14, a second time t4 for the propagation of an ultrasonic wave within a second specified distance L2 in the sub-flow path is measured. The second time is set as a propagation time changed by an amount equivalent to the change of the propagation time caused by a pulsating flow contained in the first time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flow velocity measuring method and apparatus for measuring the flow velocity of a fluid such as gas using an acoustic transducer, and a flow rate based on the gas flow velocity measured by the method and apparatus. And an ultrasonic electronic gas meter that integrates the flow rates and displays the integrated flow rate.

[0002]

2. Description of the Related Art Conventionally, as this kind of flow velocity measuring method, there is known a method called a time difference method described in Japanese Patent Publication No. 7-19638. An ultrasonic electronic gas meter that implements the proposed method, as shown in FIG.
Two acoustic transducers TD1 and TD2 composed of, for example, piezoelectric vibrators, which operate at an ultrasonic frequency and are disposed at a fixed distance L in a gas flow path 2 formed inside a housing 1 having a gas inlet 1a and an outlet 1b. And the operation of causing the other transducer TD2 or TD1 to receive the ultrasonic signal generated by one of the transducers TD1 or TD2 is performed alternately so that the ultrasonic signal becomes
The time t1 propagated in the gas flow direction and the time t2 propagated in the opposite direction to the gas flow direction between D1 and TD2 are measured, and the gas flows through the gas flow path 2 based on the two measured propagation times. The flow velocity V of the gas is determined intermittently.

[0003] Specifically, assuming that the propagation speed (sound speed) of sound in a stationary gas is c, the propagation speed of the ultrasonic signal in the forward direction of the gas flow is (c + V). Transducer TD1
The time T1 at which the ultrasonic signal from the TD1 travels in the same direction as the gas flow and reaches the transducer TD2, and the time T2 at which the ultrasonic signal from the transducer TD2 travels in the opposite direction to the gas flow and reaches the transducer TD1 are: T1 = L / (c + V) (1) T2 = L / (c−V) (2) From formulas (1) and (2), V = (L / 2) · (1 / T1-1 / T2) = (L / 2) · ((T2−T1) / (T2 · T1)) (3) , L are known, the flow velocity V can be obtained by measuring T1 and T2.

Note that T2 · T1 = L ² / (c + V) ·
Since (c−V) = L ² / (c ² −V ² ), and the flow velocity V is an extremely small value compared to the sound velocity c, V ^{2 in} the equation
Is negligibly small compared to c ² , and T2 · T1 = L
² / c ² . Then, the above equation (3) eventually, V = ((T2-T1 ) · c 2) / 2L = (T2-T1) · (c 2) · can be rewritten (1 / 2L) and. Here, Td = (T2-T
Assuming 1), V = Td · (c ² / 2L) = Td · k where k = c ² / 2L (4)

The sound velocity c in the stationary gas in the above equation (4) is communicated with the gas flow path 2 as shown in FIG. 3, but is not affected by the gas flow in the gas flow path 2. In the gas space 1c, the third acoustic transducer TD3
Is measured until the ultrasonic signal emitted from the transmitter is reflected by the wall surface 1d and returns to the transducer, and the reciprocation distance 2l from the transducer TD3 to the wall surface 1d is divided by this time, and a calculation of c = 2l / T3 is performed. Therefore, the sound speed c obtained by appropriately performing this measurement may be used, and k is 2 (1 / T).
3) It becomes ² .

When the flow velocity V is obtained, the instantaneous flow rate Q
When i is a correction coefficient that changes depending on the structure of the object or the like, Qi = Td · α · A · k = K (T3) · Td (5), and the instantaneous flow rate Qi is obtained. Here, K (T3) = α · A · k (6). Note that K (T3) is a coefficient for correction including many factors such as sound speed, gas temperature, and gas pressure, as is apparent from the above description.

The passing flow rate Qt is obtained by multiplying the instantaneous flow rate Qi obtained as described above by the intermittent time, and the integrated flow rate Q obtained by integrating the passing flow rate Qt is displayed on a display (not shown). Thereby, an ultrasonic electronic gas meter can be configured. Reference numeral 3 denotes a microcomputer (μCOM) housed in the housing 1, which controls the generation and reception of ultrasonic waves by the above-described acoustic transducers TD1 to TD3, and controls the propagation times T1 to T3 based on the received ultrasonic waves. Measurement, calculation of flow velocity, instantaneous flow rate, passing flow rate, integrated flow rate, and the like based on the measured propagation time are performed.

[0008]

The ultrasonic electronic gas meter described above is based on the premise that the flow velocity V does not fluctuate. However, some combustors that consume gas supplied through the ultrasonic electronic gas meter include: Some devices cause pressure fluctuations in the supply gas pressure during use. For example, G
In the case of an HP (gas heat pump), its use causes a variation in gas pressure of about 15 mm H ₂ O at a frequency of 10-20 Hz, which causes a pulsating flow in the gas flow, the gas flow rate changing with time. . When the flow velocity V of the gas flow in which such a pulsating flow is generated is measured intermittently by the above-described method, and the flow rate is obtained based on the measured flow rate, the error becomes large, and the flow rate is integrated. The integrated flow rate obtained as described above is a value different from the actual gas usage.

The problem of such an error becomes even greater when a pulsating flow having a period shorter than the intermittently measured period, that is, a sampling period is generated. In order to solve such a problem, the sampling period should be always reduced, but this would increase the current consumption, and if the battery was used as a power source, the period during which the battery would need to be replaced , A new problem that the length becomes shorter.

In view of the above circumstances, it is an object of the present invention to provide a novel ultrasonic flow velocity measuring method and apparatus capable of measuring a flow velocity ignoring a flow velocity change due to a pulsating flow. I have.

Another object of the present invention is to provide an ultrasonic flow rate measuring apparatus capable of measuring a flow rate ignoring a change in a flow rate caused by a pulsating flow in view of the above-mentioned situation.

In view of the above-mentioned situation, the present invention further provides an ultrasonic electronic gas meter which integrates and displays a gas flow rate estimated and measured from intermittent flow velocity measurement. It is an object of the present invention to provide an ultrasonic electronic gas meter capable of accurately integrating and displaying the gas consumption by reducing the amount of gas.

[0013]

According to the first aspect of the present invention, there is provided a method for controlling a first time in which ultrasonic waves propagate during a first predetermined distance in a main flow path through which a fluid flows. And both ends are respectively connected to the upstream side and the downstream side of the main flow path, but the fluid does not flow, and the pressure changes on the upstream side and the downstream side of the main flow path are transmitted to both ends, respectively. The second time during which the ultrasonic wave propagates between the second predetermined distances in the sub flow path is simultaneously measured, respectively, and based on the first and second times and the first and second predetermined distances. And determining the flow velocity of the fluid flowing through the main flow path.

In the method for measuring flow rate according to the first aspect,
In the main flow path through which the fluid flows, a first time during which the ultrasonic wave propagates for a first predetermined distance is measured, and almost simultaneously with this measurement, both ends are respectively connected to the upstream side and the downstream side of the main flow path. However, the fluid does not flow, and the ultrasonic wave propagates for a second predetermined distance in the sub-flow path in which the pressure changes on the upstream side and the downstream side of the main flow path are transmitted to both ends, respectively. Since the second time is measured and the second time is a propagation time that is changed by an amount corresponding to a change in the propagation time due to the pulsating flow included in the first time, the first and second times are measured. The flow velocity of the fluid flowing in the main flow path obtained based on the first and second predetermined distances may be a flow velocity that is canceled by the flow velocity due to the pulsating flow.

According to a second aspect of the present invention, the main flow path through which the fluid flows and the upstream and downstream ends of the main flow path communicate with each other, but the fluid does not flow, and the main flow path is connected to the upstream side of the main flow path. A first channel for measuring a first time during which the ultrasonic wave propagates between a sub-flow path in which the pressure change on the downstream side is transmitted to both ends and a first predetermined distance in the main flow path. An acoustic means, a second acoustic means for measuring a second time during which the ultrasonic wave propagates between a second predetermined distance in the sub-flow path, the first and second times, An ultrasonic flow velocity measuring device comprising: flow velocity calculating means for determining a flow velocity of a fluid flowing through the main flow path based on the first and second predetermined distances.

In the apparatus according to the second aspect, in the main flow path through which the fluid flows, the first acoustic means measures a first time during which the ultrasonic wave propagates for a first predetermined distance in the main flow path. The upstream and downstream ends of the main flow path communicate with each other, but no fluid flows, and the pressure changes in the upstream and downstream sides of the main flow path are transmitted to both ends of the sub flow path. , The second acoustic means measures a second time during which the ultrasonic wave propagates during a second predetermined distance in the sub-flow path, and the second time is a pulsating flow included in the first time. Of the fluid flowing through the main flow path determined by the flow velocity calculating means based on the first and second times and the first and second predetermined distances. The flow velocity may be such that the flow velocity due to the pulsating flow is canceled.

According to a third aspect of the present invention, in the device according to the second aspect, the main flow path and the sub flow path communicate with each other on the upstream side and the downstream side, but substantially restrict the flow of fluid. It has a through opening, and is partitioned by a film-shaped partition plate that can be displaced by the pressure change so as to transmit the pressure change on the upstream side and the downstream side of the main flow path to the upstream side and the downstream side of the sub flow path. The present invention resides in an ultrasonic flow velocity measuring device.

In the method according to the third aspect, the second aspect is provided.
In addition to the operation of the described invention, the main flow path and the sub flow path communicate with each other on the upstream side and the downstream side, but are partitioned by a membrane-shaped partition plate having an opening for communication that substantially restricts the flow of fluid, The main flow path and the sub flow path are usually the same because the partition plate can be displaced by the pressure change so as to transmit the pressure change on the upstream side and the downstream side of the main flow path to the upstream side and the downstream side of the sub flow path. When a pulsating flow is generated in the main flow path when the gas is filled with the gas having the same temperature and the same pressure, the pressure accompanying the pulsating flow is transmitted, and a flow corresponding to only the pulsating flow is generated in the sub flow path. The second time, which is a measured value of the propagation time of the ultrasonic wave in the flow path, is a value reflecting the pulsating flow.

According to a fourth aspect of the present invention, in the device according to the second or third aspect, the first and second acoustic means are arranged at the first and second predetermined distances from each other. Two acoustic transducers, each of the first
The time required for the second acoustic transducer to receive the ultrasonic waves emitted by the second acoustic transducer and for the second acoustic transducer to receive the ultrasonic waves after the first acoustic transducer emits the ultrasonic waves To measure the first and second time periods.

In the apparatus according to the fourth aspect, the second aspect is provided.
In addition to the operation of the invention described in the third aspect, the first and second acoustic means include first and second acoustic transducers arranged at a first and second predetermined distances, respectively,
The second acoustic transducer receives the ultrasonic waves emitted by the second acoustic transducer, and measures the time required from when the first acoustic transducer emits the ultrasonic waves to when the second acoustic transducer receives the ultrasonic waves. Since the first and second time periods are measured, the first acoustic transducer may be operated only for transmission and the second acoustic transducer may be operated exclusively for reception. Transmission and reception operations can be performed.

According to a fifth aspect of the present invention, the main flow path through which the fluid flows and the upstream and downstream ends of the main flow path communicate with each other, but the fluid does not flow, and the main flow path is connected to the upstream side of the main flow path. A first channel for measuring a first time during which the ultrasonic wave propagates between a sub-flow path in which the pressure change on the downstream side is transmitted to both ends and a first predetermined distance in the main flow path. An acoustic means, a second acoustic means for measuring a second time during which the ultrasonic wave propagates between a second predetermined distance in the sub-flow path, the first and second times, Flow rate calculating means for determining a flow rate of the fluid flowing through the main flow path based on the first and second predetermined distances, and multiplying the determined flow rate by a cross-sectional area of the means flow path to obtain a flow rate. It exists in the ultrasonic type flow measurement device.

In the apparatus according to the fifth aspect, in the main flow path through which the fluid flows, the first acoustic means measures a first time during which the ultrasonic wave propagates for a first predetermined distance in the main flow path. The upstream and downstream ends of the main flow path communicate with each other, but no fluid flows, and the pressure changes in the upstream and downstream sides of the main flow path are transmitted to both ends of the sub flow path. , The second acoustic means measures a second time during which the ultrasonic wave propagates during a second predetermined distance in the sub-flow path, and the second time is a pulsating flow included in the first time. , And the flow velocity calculating means calculates the first and second times and the first and second times.
Since the flow velocity of the fluid flowing through the main flow path determined based on the predetermined distance can be obtained by canceling the flow velocity due to the pulsating flow, the flow rate obtained by multiplying the flow velocity by the cross-sectional area of the main flow path includes: The flow rate change due to the pulsation is not included.

According to a sixth aspect of the present invention, the main flow path through which the fluid flows and the upstream and downstream ends of the main flow path are communicated with each other, but the fluid does not flow, and the main flow path is connected to the upstream side of the main flow path. A first channel for measuring a first time during which the ultrasonic wave propagates between a sub-flow path in which the pressure change on the downstream side is transmitted to both ends and a first predetermined distance in the main flow path. A second acoustic means for measuring a second time during which an ultrasonic wave propagates between a second predetermined distance in the sub-flow path, and the first and second acoustic means. A control unit for performing control for intermittently measuring the first and second times; and a control unit for controlling the flow of the fluid flowing through the main flow path based on the first and second times and the first and second predetermined distances. The flow velocity is determined intermittently, and the cross-sectional area of the means flow path and the circumference of the intermittent measurement are added to the determined flow velocity. Multiplying the calculated flow rate by passing through the main flow path, integrating the obtained flow rates to obtain an integrated flow rate, and an integrated flow rate calculating means for displaying the integrated flow rate obtained by the integrated flow rate calculating means. An ultrasonic electronic gas meter is provided.

In the apparatus according to the sixth aspect, in the main flow path through which the fluid flows, the first acoustic means measures a first time during which the ultrasonic wave propagates for a first predetermined distance in the main flow path. The upstream and downstream ends of the main flow path communicate with each other, but no fluid flows, and the pressure changes in the upstream and downstream sides of the main flow path are transmitted to both ends of the sub flow path. , The second acoustic means measures a second time during which the ultrasonic wave propagates during a second predetermined distance in the sub-flow path, and the second time is a pulsating flow included in the first time. And the flow velocity calculating means calculates the first and second times and the first and second times.
The flow velocity of the fluid flowing through the main flow path intermittently obtained based on the predetermined distance can be obtained by canceling the flow velocity due to the pulsating flow. Since the flow rate obtained by multiplying the periodic measurement cycle does not include the flow rate change due to pulsation, even if this flow rate is integrated by the integrated flow rate calculation means, the integrated flow rate displayed on the display means is the pulsating flow rate. Can be accurate without errors due to

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an ultrasonic electronic gas meter incorporating an ultrasonic flow velocity measuring device that implements the ultrasonic flow velocity measuring method of the present invention. Are denoted by the same reference numerals, and a detailed description thereof will be omitted in the following description.

In the illustrated ultrasonic electronic gas meter, the housing 1 has a gas inlet 1a and an outlet 1b, similar to the conventional one described above with reference to FIG. The other end is communicated with the gas outlet 1b, and a first gas flow path 2a is formed as a main flow path through which gas flows in from the gas inlet 1a and flows out of the gas outlet 1b. A second gas flow path 2b as a sub flow path is formed in the housing 1 in parallel with the first gas flow path 2a. However, both ends of the second gas flow path 2b are connected to the gas inlet 1a.
And the gas outlet 1b, but the communication opening 3 so that the gas flowing from the gas inlet 1a and flowing out of the gas outlet 1b does not substantially flow through the second gas flow path 2b.
The gas is separated from the gas inlet 1a and the gas outlet 1b by partition plates 3 and 4 having a and 4a.

The gas inlet 1a and the gas outlet 1b
Side, that is, when a pressure fluctuation occurs on the upstream side and the downstream side of the first gas flow path 2a, the amount of gas flowing through the communication openings 3a and 4a is limited, so that the second gas flow path 2b Although the pressure at both ends cannot follow the fluctuation, a pressure difference occurs between the two, and the partition plates 3 and 4 receive a pressure corresponding to the pressure difference.
At this time, the partition plates 3 and 4 are formed in a film shape from an elastic material such as, for example, nitrile butadiene rubber, so that the partition plates 3 and 4 are displaced to lower pressures and fluctuate in pressure. Therefore, the pressure fluctuation on the first gas flow path 2a side, which cannot be followed by the amount of gas flowing through the openings 3a and 4a of the partition plates 3 and 4, causes the displacement of the partition plates 3 and 4 to cause the second gas flow path 2b Will be transmitted to both ends.

In the first gas flow path 2a, a fixed distance L1
Acoustic transducers TD11 and TD, for example consisting of piezoelectric transducers, operating at ultrasonic frequencies separated by
12 are arranged. In the second gas flow path 2b, two similar acoustic transducers TD13 and TD14 are arranged at a fixed distance L1 or L2. The acoustic transducers TD11 and TD13 disposed upstream of the gas flow paths 2a and 2b are exclusively used for transmitting ultrasonic waves, and are operated to simultaneously emit ultrasonic waves. Gas flow paths 2a and 2b
The acoustic transducers TD12 and TD14 arranged downstream of the acoustic transducers TD11 and TD
It is exclusively used for receiving the ultrasonic waves emitted from 13.

A microcomputer (μCOM) 13 is provided in a space in the casing 1 isolated from the gas flow paths 2a and 2b.
Is provided. The μCOM 13 applies a drive signal for driving the upstream acoustic transducers TD11 and TD13 substantially simultaneously to emit ultrasonic waves almost simultaneously, and the upstream acoustic transducer TD
The operation of receiving the ultrasonic waves from the TD 11 and the TD 13 and taking in the reception signals generated by the acoustic transducers TD 12 and TD 14 on the downstream side is performed intermittently. Then, the ultrasonic waves emitted by the upstream acoustic transducers TD11 and TD13 are converted to the downstream acoustic transducers TD12 and TD13.
14 are measured so that the flow velocity V of the gas flowing in the first gas flow path 2a is intermittently calculated based on the two propagation times t1 and t4. Operate.

With the configuration described above, the gas always flows exclusively in the main flow path 2a and hardly flows in the sub flow path 2b. However, when a pulsating flow occurs due to pressure fluctuations in the main flow path 2a, the gas flows through the sub flow path 2b. Is affected by this pressure fluctuation, and a flow corresponding to a pulsating flow is generated. Now, the flow velocity of the main flow path 2a is V,
Assuming that the flow velocity is Vo, the ultrasonic wave propagation time t1 between the acoustic transducers TD11 and TD12 in the main flow path 2a.
And the propagation time t4 of the ultrasonic wave between the acoustic transducers TD13 and TD14 in the sub flow path 2b is t1 = L1 / (c + V) t4 = L2 / (c + Vo), but Vo is almost 0, so that t4 = L2 / c. From these equations, V = (L1 / t1)-(L2 / t4) is obtained.

When L1 = L2, that is, the main flow path 2a
When the propagation distance of the ultrasonic wave is equal to that of the sub flow path 2b, V = L1 · ((t4−t1) / t1t4). In this formula, T1t4 is expressed as t1t4 = ((L1 / (c + V)) · (L1 / c) = L1 2 / (c 2 + cV), since V wherein is extremely small compared to c, t1t4 = L1 ² / c ² become. When this is substituted into the above equation, V = (t4-t1) · (c 2 / L1) = however K (t4) · (t4- t1), K (t4) = (c 2 / L1), which is a coefficient that can be determined by the time t4.

Accordingly, the difference between the propagation time t1 of the main flow path 2a and the propagation time t4 of the sub flow path 2b is obtained, and the flow velocity V is obtained by multiplying the difference by a coefficient K (t4) determined by the time t4. The coefficient K (t4) is equal to the time t4
Can be determined by reading from a data table prepared in advance in a memory in the μCOM. Note that time t1
And t4 include a change due to pressure fluctuation,
By taking the difference between them, the fluctuation is canceled,
The instantaneous flow velocity V not including the pulsating flow due to the pressure fluctuation is obtained.

Specifically, the flow velocity waveform of the main flow path 2a in which the pulsating flow is superimposed on the flow and the flow velocity waveform of the sub flow path 2b due to only the pulsating flow generated by the pressure transmission without the flow are shown in FIG. And b, the differences between the propagation times t1 and t4 measured at approximately the same time in both flow paths, as indicated by crosses and black circles, allow the change in sound velocity due to the pulsating flow to be different from each other. Then, the instantaneous flow velocity V when there is no pulsating flow indicated by the dotted line is obtained.

By multiplying the instantaneous flow velocity V determined by the μCOM 13 by the above equation by the cross-sectional area A of the main flow path 2a, that is, by performing the calculation of Qi = A · K (t4) · (t4-t1) by the μCOM13 Instantaneous flow Q
i is required. Therefore, the μCOM 13 functions as a flow rate calculating means. Then, the μCOM 13 performs control for intermittently measuring the first and second times by the acoustic transducers TD11 to TD14, and performs an operation of multiplying the instantaneous flow rate Qi by the elapsed time T from the previous measurement, thereby obtaining the passing flow rate. Qt is obtained as Qt = Qi · T. Therefore, the μCOM 13 functions as a control unit that performs control for intermittently measuring the first and second times, and as an integrated flow calculation unit that obtains an integrated flow by integrating the passing flow. Further, the integrated flow rate is obtained by integrating the passing flow rate Qt, and the obtained integrated flow rate is displayed on the display 5 as an integrated value of the gas usage amount. The display 5 is actually fitted and arranged on the front of the housing 1.

In the above description, the main flow path 2a and the sub flow path 2b
It is assumed that the propagation distances of the ultrasonic waves are equal, but when the distances are not equal and L1 ≠ L2, the following arithmetic processing is performed.

That is, when L1 ≠ L2, V = (L1 / t1) − (L2 / t4) = L1 · ((t4− (L2 / L1) t1) / t1t4) In this equation, t1t4 becomes t1t4 = L1 ² / c ² as described above. Therefore, when this is substituted into the above equation, V = (t4− (L2 / L1) t1) · (c ² / L2) = K (t4) · (t4−K1t1) where K (t4) = (c ² / L2), which is a coefficient that can be determined by time t4, and K1 = (L2 / L1), a constant determined by the ratio of the propagation distances It is.

Accordingly, the difference between the propagation time t1 of the main flow path 2a and the propagation time t4 of the sub flow path 2b is obtained, and the flow velocity V is obtained by multiplying the difference by a coefficient K (t4) determined by the time t4. Note that the coefficient K (t4) can be determined by reading from the data table in the same manner as in the above example.
K1 is stored as data in a predetermined area of the memory as a fixed value according to the size of the apparatus. Of course, the flow rate Qi, the passing flow rate Qt, and the integrated flow rate are sequentially obtained based on the flow velocity V obtained as described above, as in the above-described example.

In the flow velocity measuring method according to the above-described embodiment, the predetermined distance L1
The time t1 during which the ultrasonic wave propagates between the predetermined distance L2 is measured in the sub flow path 2b at substantially the same time as measuring the time t1 during which the ultrasonic wave propagates between
Since the time t4 is a propagation time that is changed by an amount corresponding to a change in the propagation time due to the pulsating flow included in the time t1, the gas flowing through the main flow path 2a obtained based on the times t1 and t4 and the predetermined distances L1 and L2. Can be obtained by canceling the flow rate due to the pulsating flow.

In the flow velocity measuring device according to the above-described embodiment, the ultrasonic transducers TD11 and TD12 function as the first acoustic means in the main flow path 2a through which the gas flows so that the ultrasonic waves propagate between the predetermined distances L1 in the main flow path 2a. The acoustic transducers TD13 and TD14 as the second acoustic means measure the time t4 during which the ultrasonic wave propagates between the predetermined distances L2 in the sub flow path 2b in the sub flow path 2b. Since the time t4 is a propagation time that is changed by an amount corresponding to the change in the propagation time due to the pulsating flow included in the time t1, the μCOM 13 is set to the time t1 and the time t4.
Main flow path 2a calculated based on the distance L1 and the predetermined distances L1 and L2
The flow velocity of the gas flowing through the air can be such that the flow velocity due to the pulsating flow is canceled.

The main and sub flow paths 2a and 2b communicate with each other on the upstream side and the downstream side, but have membrane-like partition plates 3 having communication openings 3a and 4a for substantially restricting the flow of fluid. 4, the partition plates 3 and 4 can be displaced by the pressure change so as to transmit the pressure change on the upstream side and the downstream side of the main flow path 2a to the upstream side and the downstream side of the sub flow path 2b. The main flow path 2a and the sub flow path 2b are usually filled with a gas having the same temperature and the same pressure, and when a pulsating flow is generated in the main flow path 2a, the pressure accompanying the pulsating flow is transmitted to the sub flow path 2b. A flow corresponding to only the pulsating flow is generated, and the time t4, which is the measured value of the propagation time of the ultrasonic wave in the sub flow path 2b, is a value reflecting the pulsating flow.

Further, the second acoustic transducer TD12 or TD14 receives the ultrasonic wave emitted by the acoustic transducer TD11 or TD13, and the first acoustic transducer TD11 or TD13 emits the ultrasonic wave before the second acoustic transducer TD12. Alternatively, since the times t1 and t4 required until the TD 14 receives the ultrasonic wave are measured, the acoustic transducers TD11 and TD1 are measured.
3 is for transmission only, the acoustic transducers TD12 and T
Since D14 may be operated only for reception, it is possible to cause each acoustic transducer to reliably perform the transmission and reception of ultrasonic waves.

In the flow rate measuring device according to the above-described embodiment, in the main flow path 2a through which the gas flows, the ultrasonic transducers TD11 and TD12, which are the first acoustic means, transmit ultrasonic waves during a predetermined distance L1 in the main flow path 2a. The propagation time t1 is measured, and in the sub flow path 2b, the acoustic transducers TD13 and TD14, which are the second acoustic means, measure the time t4 during which the ultrasonic wave propagates for a predetermined distance L2 in the sub flow path 2b. The time t4 is a propagation time that is changed by an amount corresponding to a change in the propagation time due to the pulsating flow included in the time t1, and the main channel determined by the μCOM 13 based on the times t1 and t4 and the predetermined distances L1 and L2. Since the flow velocity of the gas flowing through the flow path 2a can be obtained by canceling the flow velocity due to the pulsating flow, the flow velocity is obtained by multiplying the flow velocity by the cross-sectional area of the main flow path 2a. The flow rate, will not be included the flow rate change due to pulsation.

In the electronic gas meter according to the above-described embodiment, the μCOM 13 is set at the times t1 and t4 and the predetermined distance L1.
The flow velocity of the gas flowing through the main flow path 2a intermittently obtained based on the flow rate and L2 can be obtained by canceling the flow rate due to the pulsating flow. Since the flow rate obtained by multiplying the intermittent measurement cycle does not include the flow rate change due to pulsation,
Even if this passing flow rate is integrated by the integrated flow rate calculating means, the integrated flow rate displayed on the display 5 can be accurate without including an error due to the pulsating flow.

In the above-described embodiment, the sub flow path 2
b. Transmitter and receiver acoustic transducer TD13 in b
And the TD14. Of these, the transmitting acoustic transducer TD13 is used for both transmitting and receiving, and a reflecting surface is disposed in place of the receiving transducer TD14. The transmitting and receiving acoustic transducer emits and reflects from the reflecting surface. The round-trip propagation time may be measured by causing the user to receive the sound wave.

Further, in the embodiment, the gas flow rate is measured. However, the method and apparatus of the present invention can be equally applied to those for measuring the flow rate and flow rate of a pulsating fluid.

[0046]

As described above, according to the first or second aspect of the present invention, the flow velocity of the fluid flowing through the main flow path determined based on the first and second times and the first and second predetermined distances. Can cancel the flow velocity component due to the pulsating flow, so that a new ultrasonic flow velocity measuring method and apparatus capable of measuring the flow velocity ignoring the flow velocity change due to the pulsating flow can be obtained.

Further, according to the third aspect of the present invention, when the main flow path and the sub flow path are normally filled with gas having the same temperature and the same pressure, and a pulsating flow is generated in the main flow path,
The pressure accompanying the pulsating flow is transmitted, and a flow corresponding to only the pulsating flow is generated in the sub-flow passage. The second time, which is the measured value of the propagation time of the ultrasonic wave in the sub-flow passage, Is reflected, so that an ultrasonic flow velocity measuring device in which both the change in the propagation time of the ultrasonic wave and the pulsation due to the environment are canceled is obtained.

According to the fourth aspect of the present invention, since the first acoustic transducer only needs to operate for transmission and the second acoustic transducer only needs to operate for reception, reliable transmission of ultrasonic waves to each acoustic transducer is ensured. Since the receiving operation is performed, an ultrasonic flow velocity measuring device capable of performing accurate flow velocity measurement can be obtained.

According to the fifth aspect of the present invention, the flow rate obtained by multiplying the flow velocity by the cross-sectional area of the main flow path does not include the flow rate change due to the pulsation. And an ultrasonic flow rate measuring device can be obtained.

According to the sixth aspect of the invention, the flow velocity of the fluid flowing through the main flow path intermittently determined can be obtained by canceling the flow velocity due to the pulsating flow. The flow rate obtained by multiplying the cross-sectional area of the flow path and the intermittent measurement cycle does not include the flow rate change due to pulsation, and the integrated flow rate displayed by integrating this flow rate includes the error due to the pulsation flow It is possible to reduce the error in the flow rate due to the pulsating flow, even if the flow rate of the gas estimated from the intermittent flow rate measurement is integrated and displayed. An ultrasonic electronic gas meter capable of accurately integrating and displaying gas consumption can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a flow velocity measuring device implementing an ultrasonic flow velocity measuring method according to the present invention and an ultrasonic electronic gas meter incorporating the flow measuring device.

FIG. 2 is an explanatory diagram for explaining the principle of flow velocity measurement according to the present invention.

FIG. 3 is a diagram showing a configuration of an apparatus for performing a conventional method.

[Explanation of symbols]

13 Flow velocity calculating means, flow calculating means, control means, flow integrating means (μCOM) 2a Main flow path (first gas flow path) 2b Sub flow path (second gas flow path) 3, 4 Partition plate 3a, 4a Opening 5 display means (display) TD11, TD12 First sound means (sound transducer) TD13, TD14 Second sound means (sound transducer)

Claims (6)

[Claims] A first time during which an ultrasonic wave propagates during a first predetermined distance in a main flow path through which a fluid flows, and both ends of which are communicated upstream and downstream of the main flow path, respectively. A second fluid in which the fluid does not flow, and the ultrasonic wave propagates for a second predetermined distance in the sub-flow path in which the pressure changes on the upstream side and the downstream side of the main flow path are transmitted to both ends, respectively. And measuring a flow rate of the fluid flowing through the main flow path based on the first and second times and the first and second predetermined distances, respectively. Method. 2. A main flow path through which a fluid flows, and both ends of the main flow path are connected to an upstream side and a downstream side of the main flow path, but the fluid does not flow, and a pressure change on the upstream side and the downstream side of the main flow path is reduced. Sub-channels that are respectively transmitted to both ends; first acoustic means for measuring a first time during which ultrasonic waves propagate during a first predetermined distance in the main channel; A second acoustic means for measuring a second time during which the ultrasonic wave propagates during a second predetermined distance in the sub-flow path, the first and second times, and the first and second times An ultrasonic flow velocity measuring device comprising: flow velocity calculating means for determining a flow velocity of a fluid flowing through the main flow path based on a predetermined distance. 3. The main flow path and the sub flow path communicate with each other on an upstream side and a downstream side, but have a communication opening for substantially restricting a flow of a fluid. The ultrasonic wave according to claim 2, wherein the ultrasonic wave is partitioned by a film-shaped partition plate displaceable by the pressure change so as to transmit a pressure change on the downstream side to the upstream side and the downstream side of the sub flow path. Type flow velocity measuring device. 4. The first and second acoustic means comprise first and second acoustic transducers spaced apart from each other by the first and second predetermined distances, respectively, and the first acoustic transducer emits light. The second acoustic transducer receives the ultrasonic wave, and measures the time required from when the first acoustic transducer emits an ultrasonic wave to when the second acoustic transducer receives the ultrasonic wave. The ultrasonic flow velocity measuring device according to claim 2 or 3, wherein the first and second times are measured. 5. A main flow path through which a fluid flows, and both ends are respectively connected to an upstream side and a downstream side of the main flow path, but the fluid does not flow, and a pressure change between the upstream side and the downstream side of the main flow path is reduced. Sub-channels that are respectively transmitted to both ends; first acoustic means for measuring a first time during which ultrasonic waves propagate during a first predetermined distance in the main channel; A second acoustic means for measuring a second time during which the ultrasonic wave propagates during a second predetermined distance in the sub-flow path, the first and second times, and the first and second times An ultrasonic flow rate calculating means for determining a flow rate of the fluid flowing through the main flow path based on a predetermined distance, and multiplying the obtained flow rate by a cross-sectional area of the means flow path to obtain a flow rate. Measuring device. 6. A main flow path through which a fluid flows, and both ends of the main flow path are connected to an upstream side and a downstream side of the main flow path, but the fluid does not flow, and a pressure change between the upstream side and the downstream side of the main flow path is reduced. Sub-channels that are respectively transmitted to both ends; first acoustic means for measuring a first time during which ultrasonic waves propagate during a first predetermined distance in the main channel; A second acoustic means for measuring a second time during which the ultrasonic wave propagates during a second predetermined distance in the sub flow path; and a first and a second acoustic means by the first and the second acoustic means. Control means for performing control for intermittently measuring time; and intermittently obtaining the flow velocity of the fluid flowing through the main flow path based on the first and second times and the first and second predetermined distances. Multiplying the obtained flow velocity by the cross-sectional area of the main flow path and the period of the intermittent measurement, And a display means for displaying the integrated flow rate obtained by the integrated flow rate calculating means for obtaining the integrated flow rate by calculating the passing flow rate passing through and calculating the integrated flow rate by integrating the obtained passing flow rates. Ultrasonic electronic gas meter.