JP3152824B2 - Flow measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring device for measuring a flow rate of a fluid such as a gas, and more particularly to measuring a time interval of a flow rate pulse output from a flow rate sensor and measuring a fluid flow rate from the time interval. The present invention relates to a flow rate measuring device for calculating.

[0002]

2. Description of the Related Art Conventionally, a flow measuring device of this type, for example, a gas flow measuring device for measuring a gas flow of city gas or the like, is configured as shown in FIG. This gas flow measuring device detects a gas flow and generates a flow pulse per unit metering volume.
A clock 2 for measuring a time interval of a flow pulse output from the CPU, a flow pulse output from the flow sensor 1 and a time signal output from the clock 2 are received, and a time interval of the flow pulse is calculated. And an arithmetic unit 3 for calculating a gas flow per hit.

The gas flow meter 1 comprises a gas meter 4, a magnet (magnet) 5, and a reed switch 6 for measuring a unit flow volume, as shown in FIG. The reed switch 6 uses a reed piece 6a for a contact portion and is built in a glass tube 6b.
Are turned on when approaching, and turned off when the magnet 5 separates.

In this conventional flow measuring device, each time the gas meter 4 measures a unit flow volume, the magnet 5 is separated from the reed switch 6, and as a result, the reed switch 6 is switched from on to off. It is sent to the arithmetic unit 3. The arithmetic unit 3 to which the flow pulse has been input measures the time interval of the flow pulse by the clock 2. That is, a time interval T from the time when the reed switch 6 is first turned on to off to the next time when the reed switch 6 is turned on from off is measured by the clock 2,
From the time interval T and the unit metering volume q of the gas meter 6, a flow rate Q per unit time (= q / T) is calculated.

[0005]

As described above, in the conventional flow measuring device, the flow per unit time is calculated based on the outputs of the flow sensor 11 and the clock 2. However, in the flow rate measuring apparatus having such a configuration, when noise is added to the flow rate pulse, for example, when the flow rate pulse is continuously detected in a short time, the calculated gas flow rate per unit time is the actual flow rate. Unlike this, there is a problem that the flow rate is calculated as a very large flow rate and an error increases.

[0006] Recently, in addition to a function of measuring the flow rate of gas passing therethrough, a home gas meter equipped with a microcomputer and provided with a safety function has been put into practical use. When the pressure is detected or when a predetermined gas flow rate is detected for a predetermined time or more, the gas shutoff valve is driven to shut off the gas flow path.
These functions detect leaks in pipes and unnatural gas leaks, prevent accidents before they occur, and ensure safety.To ensure that such functions operate correctly, Therefore, accurate measurement of the gas flow rate is desired.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to measure a flow rate of a fluid such as a gas, which can accurately measure a fluid flow rate even when noise is applied to the pulse. It is to provide a device.

[0008]

According to a first aspect of the present invention, there is provided a flow rate measuring device for detecting a flow rate of a fluid and outputting a flow rate pulse per unit volume, and detecting the flow rate of the fluid. At the same time, a pressure detecting means for detecting the pressure of the fluid, a time measuring means for measuring a time interval of a flow pulse outputted from the flow detecting means, a flow pulse outputted from the flow detecting means and the time measured by the time measuring means. Calculating means for calculating the fluid flow rate per unit time from the time interval of the flow pulse, and the flow rate detecting means calculates the fluid flow rate per unit time calculated by the calculating means and the pressure detected by the pressure detecting means, respectively. Storage means for storing each time a flow rate pulse is detected; and a history of fluid flow rate and pressure per unit time stored in the storage means. It is obtained by a flow correction means for correcting the fluid flow rate per unit computed time by means.

In this flow rate measuring device, the flow rate of the fluid is detected by the flow rate detecting means and a flow rate pulse per unit weighing volume is output. At the same time, the pressure of the fluid is detected by the pressure detecting means, and the flow rate detecting means is measured by the timing means. The time interval of the flow pulse output from is measured. In the calculating means, a fluid flow rate per unit time is calculated from the flow rate pulse output from the flow rate detecting means and the time interval of the flow rate pulse measured by the timing means, and the fluid flow rate per unit time calculated by the calculating means is calculated. The fluid flow rate and the pressure detected by the pressure detection means are stored in the storage means each time the flow rate detection means detects a flow pulse.
The flow rate correction means corrects the fluid flow rate per unit time calculated by the calculation means from the history of the fluid flow rate and the pressure per unit time stored in the storage means.

In the flow rate measuring device according to the second aspect, the flow rate correcting means is provided when the fluid flow rate per unit time changes by a predetermined amount or more and when the simultaneously measured pressure fluctuation amount is a predetermined amount or less. , Judge the fluid flow as noise,
The flow rate detected immediately before is approximated to the fluid flow rate at that time, thereby correcting the fluid flow rate per unit time calculated by the calculation means.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing a schematic configuration of a gas meter 10 according to one embodiment of the present invention. The gas meter 10 is provided with a safety function using a microcomputer. A gas flow path 11 having a gas inlet 16 and a gas outlet 17 is provided inside the gas meter 10. A gas 20 such as city gas flows into the gas passage 11 through a pipe (not shown).
Are supplied to a gas appliance such as a gas stove (not shown). A gas inlet 16 is provided in the gas passage 11.
In order from the side, a gas shutoff valve 12 for shutting off the gas flow path 11, a gas flow meter 13 for measuring a flow rate of gas passing through the gas flow path 11, and detecting a pressure of the gas in the gas flow path 11. Pressure detection sensors 14 are sequentially arranged.

The gas meter 10 is provided with a control unit 15 for inputting each output signal of the gas flow meter 13 and the gas pressure detection sensor 14 and controlling the gas shut-off valve 12.

FIG. 2 is a block diagram showing the configuration of the control unit 15 and its periphery in the gas meter 10 of the present embodiment.
As shown in this figure, the control unit 15 includes a CPU (central processing unit) 30, a ROM (read only memory) 31,
A random access memory (RAM) 32, a clock 33 for time measurement, and an input / output port 34;
These are connected to each other by a bus 35. A drive circuit 36 for driving the gas shutoff valve 12 is connected to the input / output port 34 in addition to the gas flow meter 13 and the gas pressure detection sensor 14 described above. In this control unit 15,
The CPU 30 uses the RAM 32 as a working area
By executing the program stored in the ROM 31, a safety function such as accurate measurement of the gas flow rate per unit time and inspection for gas leakage is realized. The RAM 32 stores the fluid flow rate per unit time and the pressure detected by the pressure detection sensor 14 for each unit time.

FIG. 3 is a functional block diagram showing functions of the flow rate measuring device of the present embodiment. As shown in this figure, the flow measuring device detects a flow rate of a fluid and outputs a flow rate pulse per unit weighing volume, and a flow rate detecting means 41. The apparatus includes a pressure detecting means 42 for detecting, and a time measuring means 43 for measuring a time interval of the flow pulse output from the flow detecting means 41. The flow detecting means 41 is realized by the gas flow meter 13, and the pressure detecting means 42 is provided by the gas pressure detecting sensor 1.
4 and the clocking means 43 is realized by the clock 33.

The flow measuring device further comprises a flow detecting means 41
Calculating means 44 for calculating the fluid flow rate per unit time from the flow rate pulse output from and the time interval of the flow rate pulse measured by the timer means 43, and the fluid flow rate per unit time calculated by the calculating means 44 A storage unit 45 for storing each pressure detected by the pressure detection unit 42 for each unit time, and a unit time calculated by the calculation unit 44 from the history of the fluid flow rate and the pressure per unit time stored in the storage unit 45 And a flow rate correcting means 46 for correcting the flow rate of the fluid per hit. Calculation means 4
4 is realized by the control unit 15, the storage unit 45 is realized by the RAM 32, and the flow rate correction unit 46 is realized by the control unit 15.

Specifically, the flow rate correcting means 46 determines whether the fluid flow rate per unit time has changed by a predetermined amount or more and the simultaneously measured pressure fluctuation amount is a predetermined amount or less. The flow rate is determined to be noise, and instead of the flow rate at that time, the flow rate detected immediately before is approximately used as the flow rate at that time, thereby correcting the calculation result of the calculation means. That is, in general, as the amount of gas used on the gas appliance side increases, the supply pressure temporarily decreases accordingly. Therefore, even though the flow rate change exceeding a certain predetermined range occurs, if the pressure measured at the same time shows only a fluctuation below a certain predetermined range, the flow pulse at this time is determined to be noise, and the immediately preceding flow pulse is therefore noise. The flow rate is approximately the flow rate at that time.

Next, a correction operation by the flow rate correction means of the flow rate measuring apparatus of the present embodiment will be described with reference to a flowchart shown in FIG.

[0019] In this embodiment, the flow rate Q _i for each unit of gas through the gas passage 11 by the flow detecting means 41 times is measured, the unit of the gas time in the gas flow path 11 by the pressure detecting means 42 Each pressure P _i is detected, and these are stored in the storage means 45 (step S100).
Next, the arithmetic unit 44 calculates the gas flow rate change amount ΔQ _i (= Q _i −Q _i−1 ) per unit time and the gas pressure change amount ΔP _i (= P _i −P _i−1 ) per unit time. It is calculated (step S101), and it is determined whether these ΔQ _i and ΔP _i satisfy the following equations (step S10).
2).

[0020]

| Q _i |> 300 l / h | P _i | <3 mmH ₂ O / h

The gas flow rate change ΔQ _i is greater than 300 l / h, and the gas pressure change ΔP _i is 3
mmH ₂ O / h or less (Step S102;
Y), the flow rate Q _i when the flow rate correction means 46 this is determined to be noise, corrects the flow rate Q _i-1, which is measured immediately before the flow rate Q _i of this time (step S10
3) Then, the flow returns to step S100 to measure the flow rate at the next time point. On the other hand, if the change amount ΔQ _i of the gas flow rate is larger than 300 liter / h and the change amount ΔP _{i of the} gas pressure does not satisfy the condition of 3 mmH ₂ O / h or less (step S102; N), the flow rate The correction unit 46 determines that the flow rate is not noise, returns to step S100 without correction, and performs the next measurement.

When the flow rate detecting means 41 detects a gas flow rate equal to or more than a predetermined amount or when a predetermined gas flow rate is detected for a predetermined time or more, the gas shut-off valve 12 is driven to open the gas flow path 11. The blocking is the same as in the prior art, and a description thereof will be omitted.

FIGS. 5 to 7 each show an example of the measurement results obtained by the fluid flow measuring device of this embodiment. FIG. 5 shows the gas flow rate including the noise component, FIG. 6 shows the measurement result of the gas supply pressure, and FIG. 7 shows the measurement result of the gas flow rate after the noise component has been removed and the correction process has been performed by the fluid flow rate measuring apparatus of this embodiment. Is represented.

As described above, in this embodiment, the flow rate detecting means 4
1, the gas supply pressure is detected by the pressure detection means 42, and the gas flow rate and the pressure are stored in the storage means 43 per unit time, and the stored fluid flow rate per unit time and The presence or absence of noise is determined based on the pressure history, and the fluid flow rate per unit time is corrected. Therefore, even when noise is present on the flow rate pulse output from the flow rate detecting means 41, the noise component can be removed to detect an accurate fluid flow rate, and thus gas leakage can be detected with high accuracy. , The safety function is improved.

In the above embodiment, the fluid to be measured is described using the gas 20 flowing through the gas meter 10, but the present invention is not limited to this.
In addition, the present invention can be applied to an apparatus for measuring the flow rate of a liquid.

[0026]

As described above, according to the flow rate measuring device of the present invention, the fluid flow rate is detected at the same time as the fluid flow rate is detected, and the fluid flow rate and the pressure are stored for each unit time. Since the fluid flow rate per unit time is corrected based on the history of the fluid flow rate and the pressure per time, an effect can be obtained in which even if the flow rate pulse includes noise, an accurate fluid flow rate can be detected. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a gas meter in a flow measurement device according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit and its periphery in FIG. 1;

FIG. 3 is a block diagram showing functions of the flow measuring device of FIG.

FIG. 4 is a flowchart for explaining a flow rate correction operation in the flow rate measuring device of FIG. 1;

FIG. 5 is a diagram illustrating an example of a temporal change of a gas flow rate including a noise component.

FIG. 6 is a diagram illustrating an example of a temporal change of a gas supply pressure.

FIG. 7 is a diagram illustrating an example of a measurement result of a gas flow rate from which a noise component has been removed.

FIG. 8 is a block diagram for explaining the principle of a conventional flow measurement device.

FIG. 9 is a block diagram illustrating a specific configuration of a conventional flow measurement device.

[Explanation of symbols]

 Reference Signs List 10 gas meter 12 gas shut-off valve 13 gas flow meter 14 gas pressure sensor 15 control unit 30 CPU (central processing unit) 32 RAM (random access memory) 33 clock (time measuring means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01F 3/22 G01F 1/00

Claims (2)

(57) [Claims] 1. Flow rate detecting means for detecting a flow rate of a fluid and outputting a flow rate pulse per unit volume, pressure detecting means for detecting a fluid flow rate and detecting a fluid pressure at the same time; Time measuring means for measuring the time interval of the flow pulse output from the detecting means, and the fluid flow per unit time from the flow pulse output from the flow detecting means and the time interval of the flow pulse measured by the time measuring means Calculation means for calculating; and a storage means for storing the fluid flow rate per unit time calculated by the calculation means and the pressure detected by the pressure detection means each time the flow rate detection means detects a flow rate pulse. The fluid per unit time calculated by the calculating means from the history of the fluid flow rate and the pressure per unit time stored in the storage means Flow measuring apparatus characterized by comprising a flow rate correction means for correcting the amount. 2. The method according to claim 1, wherein the flow rate correction unit determines that the fluid flow rate is a noise when the fluid flow rate per unit time has changed by a predetermined amount or more and the simultaneously measured pressure fluctuation amount is a predetermined amount or less. 2. The flow rate according to claim 1, wherein the fluid flow rate per unit time calculated by said calculation means is corrected by making a judgment and making the flow rate detected immediately before approximately the fluid flow rate at that time. measuring device.