JP3383577B2 - Ultrasonic flow meter and ultrasonic flow measurement method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flow meter and an ultrasonic sound meter for measuring a flow rate used in an electronic gas meter or the like.
Relates to a wave type flow measuring method, in particular, ultrasonic type flow rate to reduce pulsation of the ultrasonic flowmeter to infer intermittently measured by integrated flow the flow velocity in the flow channel (pressure fluctuations, flow rate fluctuations) the effect of It relates to an improvement of the total and ultrasonic flow measuring method.

[0002]

2. Description of the Related Art Conventionally, as a flow meter used for measuring a flow rate of an electronic gas meter, an ultrasonic type or fluidic type flow meter has been widely used. For example,
The basic principle of the ultrasonic gas flow meter will be briefly described. As shown in FIG. 6, the ultrasonic flow meter 20 operates at an ultrasonic frequency arranged in the gas flow path at a certain distance. , Has two acoustic transducers 21 and 23 made of, for example, piezoelectric vibrators, and a propagation line 22 through which ultrasonic waves propagate. For example, first, an ultrasonic signal is generated from the transducer 21 on the gas inflow side, and the gas outflow is generated. The transducer 23 on the side receives and measures the propagation time t1 of the ultrasonic signal in the gas flow direction between the transducers.

Next, the two transducers are switched to generate an ultrasonic signal from the transducer 23 on the gas outflow side, and the transducer 21 on the gas inflow side receives the ultrasonic wave signal to obtain the propagation time t2 in the direction opposite to the gas flow direction. measure. An instantaneous flow rate is obtained by intermittently obtaining the flow velocity v of the gas flowing in the propagation conduit 22 based on the difference in the propagation times of the two measured propagation times t1 and t2, and multiplying this flow velocity v by the cross-sectional area of the propagation path 22. Ask for. Then, the instantaneous flow rate is multiplied by a sampling time which is a constant measurement interval to obtain the passing flow rate, and the passing flow rate is integrated to display the integrated flow rate obtained.

[0004]

By the way, a combustor such as a gas heat pump (GHP) which consumes fluid such as gas supplied through a flow meter of this kind is subject to fluctuations in pressure and flow velocity of the supplied gas during use. Some cause pulsation.
For example, as shown in FIG. 7 (a), the gas pressure fluctuates due to the use of the combustor 30, and the pulsation 25 of the gas pressure fluctuates.
It propagates from the downstream side of 0 into the flow meter 20 and causes a measurement error. That is, as shown in FIG.
If there is a sudden pressure change due to P operation or gas shutoff,
The pressure difference ΔP between the inflow side pressure Pin and the outflow side pressure Pout of the flow meter 20 varies depending on the measurement time (ΔP1 ≠ ΔP
2). As a result, the flow velocity changes, causing a measurement error.

In addition, as shown in FIG.
In the flowmeter 20B of the two flowmeters 20A and 20B, as described above, the pulsation 25B from the combustor 30B propagates from the downstream side, and the pulsation 25A from the combustor 30A propagates from the upstream side into the flowmeter. This causes a larger measurement error. That is, in an extreme case, as shown in FIG. 8B, the outflow side pressure Pout becomes larger than the inflow side pressure Pin depending on the measurement time (ΔP3 <0), and a backflow occurs and further. There has been a problem that a large measurement error occurs, and particularly the calculation of the integrated value is greatly affected.

More specifically, when a pressure fluctuation or the like occurs as shown in FIG. 9, this causes a pulsating flow in the gas flow in which the gas flow velocity changes with time. The flow velocity v of the gas flow in which such a pulsating flow is generated is determined by the flow meter as described above at a constant sampling interval Δt
When the measured flow velocity v is multiplied by the sampling time Δt to obtain the passing flow rate, the shaded area in the figure is an error, and the cumulative flow rate obtained by integrating the passing flow rate is the actual gas usage fee. It will be a different integrated value.

The problem of such a measurement error becomes even greater when a pulsating flow having a cycle shorter than the sampling time Δt occurs. In order to solve such a problem, the sampling time Δt may be shortened, but this will increase the current consumption. Therefore, when a battery is used as a power source, there is a problem that the interval for battery replacement is shortened.

The present invention has been made in view of the above-mentioned problems, and an object thereof is an ultrasonic flowmeter capable of reducing the influence of pulsating flow and performing accurate flow measurement, and
An object is to provide an ultrasonic flow rate measuring method.

[0009]

In order to achieve the above-mentioned object, the ultrasonic flowmeter of the present invention is, as described in claim 1, arranged at a certain distance in the flow direction in the flow path.
Has two acoustic transducers in the flow path,
Generate and receive ultrasonic signals alternately between the transducers
Flow rate measurement by measuring the propagation time of ultrasonic signals
Ultrasonic flowmeter equipped with ultrasonic flowmeter
There are a pressure measuring means for detecting a pressure difference between the pressure of the pressure and the outlet near the inlet vicinity of the ultrasonic flowmeter, a conversion table for converting the pressure difference by the pressure measuring means on the flow rate value, the Flow rate measurement result by ultrasonic flow rate measuring means
Flow rate change amount detecting means for detecting the flow rate change amount based on
And the change amount of the flow rate by the flow rate change amount detecting means is predetermined.
When the amount is equal to or more than the amount, the flow rate value obtained by the conversion table is used as a flow rate measurement result of the ultrasonic flowmeter, and a control means.

The ultrasonic flowmeter according to claim 2 is
Two placed at a certain distance in the flow direction in the flow path
With the acoustic transducer of
The ultrasonic signals are generated and received alternately between the
An ultrasonic wave that measures the flow rate by measuring the propagation time of
In an ultrasonic flow meter equipped with a flow rate measuring means,
And pressure measuring means for detecting a pressure difference between the pressure of the pressure and the outlet near the inlet vicinity of the ultrasonic flowmeter, a conversion table for converting the pressure difference by the pressure measuring means on the flow rate value, before
Flow based on the flow rate measurement result by the ultrasonic flow rate measuring means.
Flow rate change amount detection means for detecting a change amount of the flow rate, and the flow rate
When the change amount of the flow rate by the change amount detection means is more than a predetermined amount
The flow rate value obtained by the conversion table
As the flow rate measurement result of the ultrasonic type flow meter , or
The flow rate measurement result by the wave type flow rate measuring means is below the predetermined flow rate.
Sometimes, the flow rate value obtained by the conversion table is
A control unit which is a flow rate measurement result of the ultrasonic flow meter ,
It is equipped with.

[0011]

In the ultrasonic type flow rate measuring method according to a third aspect of the invention, the ultrasonic flow rate measuring method is arranged with a certain distance in the flow direction in the flow path.
With two acoustic transducers in the flow path
Ultrasonic signals are generated and received alternately between the juicers.
Flow rate is measured by measuring the propagation time of wave signal
Ultrasonic flow rate measuring means, pressure measuring means for detecting the pressure difference between the pressure near the inlet and the pressure near the outlet of the flow path ,
In the ultrasonic flow rate measuring method for an ultrasonic flow meter including: a converting step for converting a pressure difference by the pressure measuring means into a flow rate value based on a conversion table; and the ultrasonic flow rate measuring means. Flow rate change amount detecting step for detecting a flow rate change amount based on the flow rate measurement result, a second determining step for determining whether or not the flow rate change amount by the flow rate change amount detecting step is a predetermined amount or more, and the second And an output step of setting the flow rate value obtained in the conversion step as a flow rate measurement result of the ultrasonic flowmeter when it is determined that the flow rate value is equal to or larger than a predetermined amount in the determination step.

Further, in the ultrasonic type flow rate measuring method according to the fourth aspect, the ultrasonic flow rate measuring method is arranged with a certain distance in the flow direction in the flow path.
With two acoustic transducers in the flow path
Ultrasonic signals are generated and received alternately between the juicers.
Flow rate is measured by measuring the propagation time of wave signal
Ultrasonic flow rate measuring means, pressure measuring means for detecting the pressure difference between the pressure near the inlet and the pressure near the outlet of the flow path ,
In the ultrasonic flow rate measuring method for an ultrasonic flow meter including: a converting step for converting a pressure difference by the pressure measuring means into a flow rate value based on a conversion table; and the ultrasonic flow rate measuring means. A first determination step for determining whether or not the flow rate measurement result by the flow rate is less than or equal to a predetermined flow rate, a flow rate change amount detection step for detecting a flow rate change amount based on the flow rate measurement result by the ultrasonic flow rate measurement means, and the flow rate change A second determination step of determining whether or not the amount of change in the flow rate by the amount detection step is equal to or more than a predetermined amount, and whether the flow rate is less than or equal to a predetermined flow rate in the first determination step, or greater than or equal to a predetermined amount in the second determination step. When determined, the flow rate value obtained by the conversion step is used as a flow rate measurement result of the ultrasonic flow meter, and an output step is provided.

[0014]

An ultrasonic flowmeter and an ultrasonic flowmeter according to claim 1 of the present invention.
In the ultrasonic flow rate measuring method according to the pre claim 3, ultrasonic
The flow rate in the flow path is intermittently measured by the flow rate measuring means to estimate the integrated flow rate, and in parallel, the pressure near the inlet and the pressure near the outlet of the ultrasonic flow meter are measured by the pressure measuring means. The pressure difference by the pressure measuring means is converted into a flow rate value by a conversion table (conversion step), and the flow rate change amount detecting means detects the flow rate by the ultrasonic type flow rate measuring means. After detecting the amount of change in the flow rate (flow rate change detecting step) based on the above, when the amount of change in the flow rate by the flow rate change detecting means is equal to or larger than a predetermined amount (second determination step), the control table uses the conversion table. The obtained flow rate value is used as the flow rate measurement result of the flow meter (output step). As described above, when the pulsating flow of the pressure fluctuation or the flow velocity fluctuation is particularly remarkable based on the detection of the flow rate change amount, the measurement method that is hardly affected by the pulsating flow of the pressure fluctuation or the flow velocity fluctuation, that is, the pressure measuring means detects the pulsating flow. Since the flow rate is obtained by using the measuring method for converting the pressure difference into the flow rate value by the conversion table, the measurement accuracy of the flow rate measurement and the flow rate integration can be improved.

Further, an ultrasonic flow according to claim 2 of the present invention
In the meter and the ultrasonic flow rate measuring method according to claim 4 ,
The ultrasonic flow rate measuring means intermittently measures the flow velocity in the flow path to estimate the integrated flow rate, and at the same time, the pressure measuring means simultaneously measures the pressure near the inlet and the vicinity of the outlet of the ultrasonic flow meter. The pressure difference with the pressure is detected, the pressure difference by the pressure measuring means is converted into a flow rate value based on the conversion table in the converting step, and the flow rate is measured by the ultrasonic flow rate measuring means in the first determining step. It is determined whether or not the result is less than or equal to a predetermined flow rate, and in the flow rate change amount detection step, the change amount of the flow rate is detected based on the flow rate measurement result by the ultrasonic flow rate measuring means,
In the second determination step, it is determined whether or not the flow rate change amount in the flow rate change amount detection step is greater than or equal to a predetermined amount, and in the output step, it is determined that the flow rate is less than or equal to the predetermined flow rate in the first determination step, or in the second determination step. When it is determined that the flow rate is equal to or more than the predetermined amount, the flow rate value obtained in the conversion step is used as the flow rate measurement result of the flow meter. As described above, when the pulsating flow of the pressure fluctuation or the flow velocity fluctuation is considered to be particularly remarkable at a low flow rate, or when the pulsating flow of the pressure fluctuation or the flow velocity fluctuation is particularly remarkable based on the detection of the flow rate change amount. almost not subjected measurement method the effect of the pulsating flow of the pressure variation and flow rate fluctuations, that is, determining the flow rate using a measurement technique to convert the flow rate value by the conversion table the pressure difference detected by the pressure measuring means, ultrasonic type flow rate It is possible to improve the measurement accuracy of measurement and flow rate integration. Especially when it is applied to an electronic gas meter or the like having a pressure monitoring function, it is possible to suppress the issuance of an erroneous warning due to the pulsating flow at a low flow rate, and to enhance the reliability of the pressure monitoring function. .

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An ultrasonic flowmeter according to the present invention (hereinafter simply referred to as "flowmeter" or "ultrasonic flowmeter")
Flow meter ". ) And ultrasonic flow rate measurement method (below
After that, we simply call it "flow rate measurement method" or "ultrasonic method".
Flow measurement method ”. 1) to 5 will be described in detail with reference to FIGS. Here, FIG. 1 is a configuration diagram showing a basic configuration of a flow meter according to an embodiment of the present invention, FIG. 2 is a configuration diagram illustrating a configuration example of a flow meter of the embodiment, and FIG. 3 is an embodiment. FIG. 4 is an explanatory view for explaining the contents of the conversion table of the flow meter, FIG. 4 is a flow chart for explaining the procedure of the flow rate measuring method of the flow meter of the embodiment, and FIG. 5 is detected when a pulsating flow of pressure fluctuation or flow speed fluctuation occurs. It is an explanatory view explaining the characteristics of the pressure difference and the flow velocity.

The flow meter of this embodiment will be described with reference to FIG. 1. The flow meter is an ultrasonic flow rate measuring means 1.
(Hereinafter, simply referred to as "flow rate measuring means 1" or
Sound wave type flow rate measuring means 1 ". ) , Pressure measuring means 2,
The conversion table 3, the flow rate change amount detecting means 4, and the control means 5 are provided.

The flow rate measuring means 1 is an ultrasonic type flow meter equivalent to the conventional example (see FIG. 6 ), which intermittently measures the flow velocity in the flow path and estimates the integrated flow rate. That is, as shown in FIG. 2, two acoustic transducers 21 and 23, which are piezoelectric transducers arranged at a certain distance in the flow path 10 and operate at ultrasonic frequencies, and a propagation tube through which ultrasonic waves propagate. The basic principle of measurement is the same as that described in the conventional example.

The pressure measuring means 2 detects the pressure difference between the pressure in the vicinity of the inlet 11 and the pressure in the vicinity of the outlet 12 of the flow meter, and is realized by a pressure sensor or the like.
Even in the conventional example (see FIG. 6 ), this pressure sensor is arranged near the inlet, and when the flow meter is applied to an electronic gas meter or the like, the gas pressure in the gas flow path is monitored to improve safety. It realizes the pressure monitoring function.
This pressure monitoring function includes, for example, pressure type micro leak warning,
Adjustment pressure abnormality warning, blockage pressure abnormality warning, pressure drop cutoff,
There are leak inspection, adjustment pressure data storage, etc.

That is, in the flow meter of this embodiment, a pressure sensor or the like conventionally arranged in the flow meter is provided separately from the flow rate measuring chamber 7 for measuring the flow rate by the flow rate measuring means 1 as shown in FIG. The pressure measuring means 2 is arranged in the pressure measuring chamber 6 provided, and the inflow side pressure Pin and the outflow side pressure Pout are set.
It is intended to detect the pressure difference ΔP (pressure loss) between and. The pressure sensor and the like are also utilized as pressure monitoring means for realizing the pressure monitoring function as in the conventional example. In addition, the structure of the flow meter of the present embodiment shown in FIG.
Since the conventional upstream chamber and the downstream chamber are fitted with the measuring unit and the conventional two chambers, the pressure measuring chamber 6 is added to the conventional upstream chamber and the downstream chamber. Therefore, it is possible to manufacture without significantly increasing the manufacturing cost as compared with the conventional flowmeter.

Next, the conversion table 3 includes the pressure measuring means 2
The pressure difference due to is converted into a flow rate value.
It is realized by tabular data stored in M.
That is, the relationship between the pressure difference ΔP between the inflow side pressure Pin and the outflow side pressure Pout and the flow rate PQ has a characteristic as shown in FIG. 3, and the characteristic is expressed in tabular data as the conversion table 3. Becomes Note that the characteristics shown in FIG. 3 can be obtained by an experiment, and tabular data is formed based on the characteristic data obtained by an experiment conducted in advance, and this is stored in the ROM or RAM. You can leave it.

Further, the flow rate change amount detection means 4 is based on the flow rate measurement result SQ by the flow rate measurement means 1 and the flow rate change amount Δ.
The control means 5 detects the SQ, and when the flow rate measurement result SQ by the flow rate measuring means 1 is less than or equal to a predetermined flow rate, or the flow rate change amount ΔSQ by the flow rate change amount detecting means 4.
Is a predetermined amount or more, the flow rate value PQ obtained by the conversion table 3 is used as the flow rate measurement result Q of the flow meter. The flow rate change amount detection means 4 and the control means 5 are
It is realized by a software program executed on a microprocessor (MPU).

Next, a flow rate measuring method in the flow meter of this embodiment will be described with reference to the flowchart of FIG.
First, in step S401, the flow rate measuring means 1 intermittently measures the flow velocity in the flow path 10. In parallel with this, in step S411, the pressure measuring means 2 detects the pressure difference ΔP between the inflow side pressure Pin near the inflow port 11 and the outflow side pressure Pout near the outflow port 12 of the flow meter. Sampling interval Δt for measuring the flow velocity by the flow rate measuring means 1
Is preferably set as short as possible in consideration of power consumption. The sampling interval Δt may be fixed as in the conventional example or may be variable (for example, randomly changed within a predetermined range).

Next, in step S402 (first determining step), it is determined whether or not the flow rate measurement result SQ by the flow rate measuring means 1 is less than or equal to a predetermined flow rate, and if it is less than or equal to the predetermined flow rate, the flow rate exceeds the predetermined flow rate in step S412. If so, the process proceeds to step S403. Here, the predetermined flow rate is, for example, 0.05 Qma when applied to an electronic gas meter or the like.
x (Qmax is the maximum flow rate), and when it is 0.05 Qmax or less, it is determined to be a low flow rate. Specifically, for example, 2.5 m ³
In the / h type, 125 L / h or less is treated as a low flow rate.

Further, in step S403 (flow rate change amount detection step), the flow rate change amount Δ based on the flow rate measurement result SQ of the flow rate measurement means 1 by the flow rate change amount detection means 4.
Detect SQ. Then, in step S404 (second determination step), it is determined whether or not the detected flow rate change amount ΔSQ is equal to or more than a predetermined amount. If the amount of change ΔSQ is equal to or more than the predetermined amount, the process proceeds to step S412, and if the amount is less than the predetermined amount, to step S405. move on. That is, the flow rate change amount ΔSQ becomes equal to or larger than the predetermined amount when a pulsating flow having a large speed fluctuation value is generated, and it is determined in the second determination step whether or not the pulsating flow is generated.

Therefore, if it is determined that the flow rate is low or pulsating flow is generated, the process proceeds to step S412. In step S412 (conversion step), the pressure difference ΔP by the pressure measuring means 2 is converted. Table 3
Is converted to a flow rate value PQ based on
In (output step), the converted flow rate value PQ is used as the flow rate measurement result Q of the flow meter. On the other hand, when it is determined that the flow rate is not low or that the pulsating flow is not generated, the process proceeds to step S405, and the flow rate measurement result SQ by the flow rate measuring means 1 is set as the flow rate measurement result Q of the flow meter.
Then, after further integrating the flow rate Q of the measurement result in step S406, the process returns to steps S401 and S411 again.

As described in detail above, in the flowmeter and the flowrate measuring method of this embodiment, the flowrate measuring means 1 intermittently measures the flow velocity in the flow path to estimate the integrated flowrate, and in parallel, The inflow side pressure Pin near the inflow port 11 and the outflow side pressure Pou near the outflow port 12 are measured by the pressure measuring means 2.
The pressure difference ΔP from t is detected, and the conversion step (step S
412), the pressure difference ΔP by the pressure measuring means 2 is converted into the flow rate value PQ based on the conversion table 3, and in the flow rate change amount detecting step (step S403), the flow rate change amount detecting means 4 determines the flow rate based on the flow rate measurement result SQ. Of the flow rate measurement result SQ by the flow rate measurement means 1 is determined by the control means 5 in the first determination step (step 402), and the second determination step (step 402). In S404), the flow rate change amount Δ
It is determined whether SQ is equal to or more than a predetermined amount, and further, when it is determined in the output step (step S413) that the flow rate is less than or equal to the predetermined amount in the first determination step, or in the second determination step that it is greater than or equal to the predetermined amount, The flow rate value PQ obtained by the conversion step is used as the flow rate measurement result of the flow meter.

As described above, in the flow meter and the flow rate measuring method of the present embodiment, it is possible to detect the flow rate change amount ΔSQ at a low flow rate when the influence of the pulsating flow such as the pressure fluctuation and the flow velocity fluctuation is particularly remarkable. When it is determined that the pulsating flow due to the pressure fluctuation or the flow velocity fluctuation is generated based on the measurement method, that is, the pressure difference ΔP detected by the pressure measuring means 2 is hardly affected by the pulsating flow due to the pressure fluctuation or the flow velocity fluctuation. Since the flow rate is obtained by using the measurement method of converting the flow rate value PQ by the conversion table 3, the measurement accuracy of flow rate measurement and flow rate integration can be improved.

The explanation of FIG. 5 shows that the measuring method for converting the pressure difference ΔP detected by the pressure measuring means 2 into the flow rate value PQ by the conversion table 3 is hardly affected by the pulsating flow of pressure fluctuation and flow speed fluctuation. Is clear from. That is, in contrast to the occurrence of pulsating flow (pressure fluctuation) as shown in FIG. 5A, the fluctuation of the flow velocity is remarkable as shown in FIG. 5C, but the pressure difference ΔP = Pin−Pout is As shown in FIG. 5B, they are averaged and have almost no temporal fluctuation. That is, in principle, the pressure difference ΔP is the difference between two physical quantities, and it is easy to obtain an average value as compared with the flow rate measurement result SQ by the flow rate measuring means 1 that is measured as it is as one physical quantity. It is a thing. That is, since the flow rate measuring means 1 does not measure the flow velocity as the velocity difference, it is difficult to average it.

Further, particularly when the flowmeter of this embodiment is applied to an electronic gas meter or the like having a pressure monitoring function, as described above, the pressure measuring means (pressure sensor or the like) 2 is used in the gas flow path. Although the gas pressure is monitored and secured by the pressure monitoring function, if the gas pressure and the flow rate value or the integrated flow rate value according to the flow rate measuring method of the present embodiment are also monitored to realize the pressure monitoring function. Further, it is possible to suppress the issuance of an erroneous warning and the erroneous forced shutoff operation at a low flow rate where the influence of the pulsating flow is particularly remarkable, and it is possible to enhance the reliability of the pressure monitoring function.

In the flow meter of this embodiment described above, ultrasonic flow rate measuring means is assumed as shown in FIGS. 1 and 2, but the flow meter is not limited to the ultrasonic type. It is also applicable to a flow meter provided with other flow rate measuring means such as a fluidic type or an impeller or a turbine type. This is because it is obvious that the output of the other flow rate measuring means also varies as long as the pulsating flow is transmitted.

[0033]

As described above, the ultrasonic wave of the present invention is used.
According to equation flowmeter and ultrasonic type flow measuring method, ultrasonic
The flow rate in the flow path is intermittently measured by the flow rate measuring means to estimate the integrated flow rate, and in parallel, the pressure near the inlet and the pressure near the outlet of the ultrasonic flow meter are measured by the pressure measuring means. Is detected and the pressure difference by the pressure measuring means is converted into a flow rate value by a conversion table (conversion step), and the control means that the influence of pulsating flow such as pressure fluctuation and flow velocity fluctuation is particularly remarkable. At low flow rate
Of the flow rate fluctuation based on the detection of the flow rate change amount.
When the pulsating flow is particularly remarkable, the flow rate is measured using a measurement method that is hardly affected by the pulsating flow due to pressure fluctuations and flow velocity fluctuations, that is, a measurement method that converts the pressure difference detected by the pressure measuring means into a flow rate value using a conversion table. Therefore, it is possible to improve the measurement accuracy of ultrasonic flow rate measurement and flow rate integration, especially when applied to an electronic gas meter equipped with a pressure monitoring function, etc. It is possible to suppress the issuance of an erroneous warning due to, and it is possible to enhance the reliability of the pressure monitoring function.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a basic configuration of a flow meter according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a configuration example of a flow meter according to an embodiment.

FIG. 3 is an explanatory diagram illustrating contents of a conversion table of the flow meter according to the embodiment.

FIG. 4 is a flowchart illustrating a procedure of a flow rate measuring method of the flow meter according to the embodiment.

FIG. 5 is an explanatory diagram illustrating characteristics of a pressure difference and a flow velocity detected when a pulsating flow due to a pressure change or a flow velocity change occurs.

FIG. 6 is an explanatory diagram illustrating the basic principle of an ultrasonic gas flow meter.

FIG. 7 is an explanatory diagram for explaining generation of a pulsating flow due to pressure fluctuation and flow speed fluctuation.

FIG. 8 is an explanatory diagram illustrating occurrence of a measurement error when pressure changes.

FIG. 9 is an explanatory diagram illustrating characteristics of pulsating flow such as pressure fluctuation and flow speed fluctuation.

[Explanation of symbols]

1 Flow rate measuring means 2 Pressure measuring means (pressure sensor) 3 Conversion table (RAM, ROM) 4 Flow rate change amount detection unit (MPU) 5 Control means (MPU) 6 Flow rate measurement room 7 Pressure measurement room 10 channels 11 Inlet 12 Outlet Pin Inflow side pressure Pout Outflow side pressure ΔP Pressure difference (pressure loss) SQ, PQ flow rate ΔSQ Flow rate change Q Flow rate measurement result 20, 20A, 20B Flowmeter 21,23 acoustic transducer 22 Propagation pipeline 25, 25A, 25B pulsating flow 30,30A, 30B Combustor

Claims (4)

(57) [Claims] 1. A fixed distance in the flow direction in the flow path
Has two acoustic transducers placed in the flow path,
Ultrasonic signals are alternately generated and received between the transducers.
By measuring the propagation time of the ultrasonic signal,
Ultrasonic flowmeter equipped with ultrasonic flowmeter for measuring
In a conversion table for converting a pressure measuring means for detecting a pressure difference between the pressure of the pressure and the outlet near the inlet vicinity of the ultrasonic flowmeter, a pressure difference by the pressure measuring means on the flow rate value, the Based on the flow rate measurement result by ultrasonic type flow rate measuring means
The flow rate change amount detecting means for detecting the flow rate change amount, and the flow rate change amount by the flow rate change amount detecting means are equal to or more than a predetermined amount.
When the above ultrasonic flowmeter, characterized in that and a control means for the flow rate measurement result of the said flow rate value determined by the conversion table ultrasonic flowmeter. 2. A certain distance in the flow direction in the flow path
Has two acoustic transducers placed in the flow path,
Ultrasonic signals are alternately generated and received between the transducers.
By measuring the propagation time of the ultrasonic signal,
Ultrasonic flowmeter equipped with ultrasonic flowmeter for measuring
In a conversion table for converting a pressure measuring means for detecting a pressure difference between the pressure of the pressure and the outlet near the inlet vicinity of the ultrasonic flowmeter, a pressure difference by the pressure measuring means on the flow rate value, the Based on the flow rate measurement result by ultrasonic type flow rate measuring means
The flow rate change amount detecting means for detecting the flow rate change amount, and the flow rate change amount by the flow rate change amount detecting means are equal to or more than a predetermined amount.
When the above, the flow rate value obtained by the conversion table as the flow rate measurement result of the ultrasonic flow meter , or,
The flow rate measurement result by the ultrasonic flow rate measuring means is a predetermined flow rate.
When less than the amount, calculated by the conversion table
An ultrasonic flow meter, comprising: a control unit that sets a flow rate value as a flow rate measurement result of the ultrasonic flow meter. 3. A certain distance in the flow direction in the flow path
Has two acoustic transducers placed in the flow path,
Ultrasonic signals are alternately generated and received between the transducers.
By measuring the propagation time of the ultrasonic signal,
Ultrasonic flow rate of an ultrasonic flow meter equipped with an ultrasonic flow rate measuring means for measuring the pressure and a pressure measuring means for detecting a pressure difference between the pressure near the inlet and the pressure near the outlet of the flow path. In the measuring method, a conversion step of converting a pressure difference by the pressure measuring means into a flow rate value based on a conversion table, and a flow rate change amount detecting step of detecting a flow rate change amount based on a flow rate measurement result by the ultrasonic flow rate measuring means. And a second determination step of determining whether or not the flow rate change amount by the flow rate change amount detection step is equal to or greater than a predetermined amount; The flow rate value
Ultrasonic flow measuring method characterized by comprising an output step of the flow rate measurement result of the ultrasonic flowmeter, the. 4. A certain distance in the flow direction in the flow path
Has two acoustic transducers placed in the flow path,
Ultrasonic signals are alternately generated and received between the transducers.
By measuring the propagation time of the ultrasonic signal,
Ultrasonic flow rate of an ultrasonic flow meter equipped with an ultrasonic flow rate measuring means for measuring the pressure and a pressure measuring means for detecting a pressure difference between the pressure near the inlet and the pressure near the outlet of the flow path. In the measurement method, a conversion step of converting the pressure difference by the pressure measurement means into a flow rate value based on a conversion table, and a first determination step of determining whether or not the flow rate measurement result by the ultrasonic flow rate measurement means is less than or equal to a predetermined flow rate. And a flow rate change amount detecting step of detecting a flow rate change amount based on a flow rate measurement result by the ultrasonic flow rate measuring means, and determining whether or not the flow rate change amount by the flow rate change amount detecting step is a predetermined amount or more. Whether the flow rate is below a predetermined flow rate in the second determination step and the first determination step,
Or an output step of setting the flow rate value obtained in the conversion step as a flow rate measurement result of the ultrasonic flow meter when it is determined in the second determination step that the amount is equal to or more than a predetermined amount. Ultrasonic flow measurement method.