JPH07151575A - Flow measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] To enable accurate measurement of the fluid flow rate even when noise is present in the flow rate pulse of fluid such as gas. A gas cutoff valve 12 for shutting off the gas flow path 11, a gas flow meter 13 for measuring the flow rate of gas passing through the gas flow path 11, and a gas flow path 1 are provided in the gas flow path 11.
A gas pressure detection sensor 14 for detecting the pressure of the gas in the gas generator 1 is sequentially arranged. In the control unit 15, when the fluid flow rate per unit time changes by a predetermined amount or more,
And when the fluctuation amount of the pressure measured at the same time is less than or equal to a predetermined amount, the fluid flow rate is determined to be noise, and the flow rate measured immediately before is approximately set as the fluid flow rate at that time.
Correct the fluid flow rate per unit time.

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 the flow rate of a fluid such as gas, and more particularly to measuring the time interval of flow rate pulses output from a flow rate sensor, The present invention relates to a flow rate measuring device for calculation.

[0002]

2. Description of the Related Art Conventionally, a flow rate measuring apparatus of this type, for example, a gas flow rate measuring apparatus for measuring the gas flow rate of city gas or the like is constructed as shown in FIG. This gas flow rate measuring device detects a gas flow rate and generates a flow rate pulse per unit metered volume, and this flow rate sensor 1
The time interval of the flow rate pulse is calculated by receiving the clock 2 for measuring the time interval of the flow rate pulse output from the flow rate sensor, the flow rate pulse output from the flow rate sensor 1 and the timing signal output from the clock 2, and calculating the unit time. The calculation device 3 for calculating the gas flow rate per hit.

As shown in FIG. 9, the gas flow meter 1 is composed of a gas meter 4 for measuring a unit flow volume, a magnet 5 and a reed switch 6. The reed switch 6 uses the reed piece 6a for the contact portion and is built in the glass tube 6b.
When the magnet 5 approaches, it turns on, and when the magnet 5 moves away, it turns off.

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

[0005]

As described above, in the conventional flow rate measuring device, the flow rate per unit time is calculated based on the outputs of the flow rate sensor 11 and the clock 2. However, in the flow rate measuring device having such a configuration, when the flow rate pulse has noise, 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 the above, there was a problem that the error was large because it was calculated as a very large flow rate.

Recently, as a gas meter for home use, a meter equipped with a microcomputer and a safety function in addition to the function of measuring the flow rate of passing gas has been put into practical use. Is detected or when a predetermined gas flow rate is detected for a predetermined time or longer, the gas cutoff valve is driven to cut off the gas flow path.
These functions detect leaks in pipes, outflows of unnatural gas, etc. to prevent accidents and ensure safety, and in order for such functions to operate correctly, Accurate measurement of gas flow rate is desired.

The present invention has been made in view of the above problems, and an object thereof is to measure a flow rate of a fluid accurately even when a flow pulse of a fluid such as gas has noise. To provide a device.

[0008]

According to a first aspect of the present invention, there is provided a flow rate measuring device which detects a flow rate of a fluid and outputs a flow rate pulse per unit measurement volume, and when the flow rate detecting means detects the fluid flow rate. At the same time, pressure detecting means for detecting the pressure of the fluid, time measuring means for measuring the time interval of the flow rate pulse output from the flow rate detecting means, flow rate pulse output from the flow rate detecting means and the time measuring means The calculating means for calculating the fluid flow rate per unit time from the time interval of the flow rate pulse, the fluid flow rate per unit time calculated by this calculating means and the pressure detected by the pressure detecting means are respectively detected by the flow rate detecting means. The storage means for storing the flow rate pulse each time it is detected, and the history of the 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 the flow rate pulse per unit measurement 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 detected by the timing means. The time interval of the flow rate pulse output from is measured. Then, the calculation means calculates the fluid flow rate per unit time from the flow rate pulse output from the flow rate detection means and the time interval of the flow rate pulse measured by the time measurement means, and the fluid flow rate per unit time calculated by this calculation 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 rate 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 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 used when the fluid flow rate per unit time changes by a predetermined amount or more and the fluctuation amount of the pressure measured at the same time is less than the predetermined amount. , Judge the fluid flow rate as noise,
The flow rate detected immediately before is approximately set as the fluid flow rate at that time, so that the fluid flow rate per unit time calculated by the calculating means is corrected.

[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 an embodiment of the present invention. The gas meter 10 has a safety function using a microcomputer. Inside the gas meter 10, a gas flow path 11 having a gas inlet 16 and a gas outlet 17 is provided. A gas 20 such as city gas flows into the gas passage 11 through a pipe (not shown), and the gas 20
Are supplied to a gas appliance such as a gas stove (not shown). A gas inlet 16 is provided in the gas passage 11.
A gas shutoff valve 12 for shutting off the gas passage 11, a gas flow meter 13 for measuring the flow rate of the gas passing through the gas passage 11, and a pressure of the gas in the gas passage 11 are detected in order from the side. A gas pressure detection sensor 14 is sequentially arranged.

A control unit 15 for controlling the gas cutoff valve 12 by inputting the output signals of the gas flow meter 13 and the gas pressure detection sensor 14 is provided in the gas meter 10.

FIG. 2 is a block diagram showing the configuration of the control unit 15 and its peripherals in the gas meter 10 of this embodiment.
As shown in this figure, the control unit 15 includes a CPU (Central Processing Unit) 30, a ROM (Read Only Memory) 31,
A RAM (random access memory) 32, a clock 33 for measuring time, and an input / output port 34 are provided,
These are connected to each other by a bus 35. A drive circuit 36 for driving the gas cutoff 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, safety functions such as accurate measurement of gas flow rate per unit time and inspection of gas leakage are 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 the functions of the flow rate measuring apparatus of this embodiment. As shown in this figure, the flow rate measuring device detects a flow rate of a fluid and outputs a flow rate pulse per unit volume, and a flow rate detecting means 41 detects the flow rate of the fluid and at the same time detects the pressure of the fluid. The pressure detecting means 42 for detecting and the time measuring means 43 for measuring the time interval of the flow rate pulse output from the flow rate detecting means 41 are provided. The flow rate detecting means 41 is realized by the gas flow meter 13, and the pressure detecting means 42 is the gas pressure detecting sensor 1.
4 and the clock means 43 is realized by the clock 33.

The flow rate measuring device further comprises a flow rate detecting means 41.
Calculating means 44 for calculating the fluid flow rate per unit time from the flow rate pulse output from the flow rate pulse and the time interval of the flow rate pulse measured by the timing means 43, and the fluid flow rate per unit time calculated by the calculating means 44 and A storage unit 45 that stores 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 pressure per unit time stored in this storage unit 45. And a flow rate correction means 46 for correcting the flow rate of the hit fluid. Computing means 4
4 is implemented by the control unit 15, the storage unit 45 is implemented by the RAM 32, and the flow rate correction unit 46 is implemented by the control unit 15.

In the flow rate correcting means 46, specifically, when the fluid flow rate per unit time changes by a predetermined amount or more, and the fluctuation amount of the pressure measured at the same time is less than the predetermined amount, the The flow rate is determined to be noise, and the flow rate detected immediately before is approximated to the flow rate at that time, instead of the flow rate at that time, and the calculation result of the calculation means is corrected. That is, in general, when the amount of gas used on the gas appliance side increases, the supply pressure temporarily decreases accordingly. Therefore, even if the flow rate change exceeds a certain predetermined range, if the pressure measured at the same time shows only a variation within a predetermined range or less, it is judged that the flow rate pulse at this time is noise, and therefore the immediately preceding The flow rate is approximately the flow rate at that time.

Next, the correcting operation by the flow rate correcting means of the flow rate measuring apparatus of this embodiment will be described with reference to the flow chart shown in FIG.

In this embodiment, the flow rate detecting means 41 measures the flow rate Q _i of the gas passing through the gas flow path 11 per unit time, and the pressure detecting means 42 measures the gas flow rate within the gas flow path 11 per unit time. The respective pressures P _i are detected and stored in the storage means 45 (step S100).
Next, the calculating means 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, respectively. It is calculated (step S101), and it is determined whether these ΔQ _i and ΔP _i satisfy the following expressions (step S10).
2).

[0020]

[Equation 1] | Q _i |> 300 liters / h | P _i | <3 mmH ₂ O / h

The change amount ΔQ _{i of} gas flow rate is larger than 300 liters / h, and the change amount ΔP _{i of} gas pressure is 3
If it is less than or equal to mmH ₂ O / h (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 process returns to step S100 and the flow rate at the next time point is measured. On the other hand, when the change amount ΔQ _i of the gas flow rate is larger than 300 liters / 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 correction means 46 determines that this 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 of a predetermined amount or more, or when a predetermined gas flow rate is detected for a predetermined time or more, the gas shutoff valve 12 is driven to open the gas flow path 11. Since the interruption is the same as the conventional one, its explanation is omitted.

5 to 7 each show an example of the measurement result by the fluid flow rate measuring apparatus of this embodiment. FIG. 5 is a gas flow rate including a noise component, FIG. 6 is a measurement result of the gas supply pressure, and FIG. 7 is a measurement result of the gas flow rate corrected by the noise component by the fluid flow rate measuring device of the present embodiment. Is represented.

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

In the above embodiment, the fluid to be measured was explained using the gas 20 flowing through the gas meter 10, but the present invention is not limited to this.
It is also applicable to other devices that measure the flow rate of liquid.

[0026]

As described above, according to the flow rate measuring device of the present invention, the fluid flow rate is detected, the fluid pressure is detected at the same time, and the fluid flow rate and the pressure are stored for each unit time, and the stored unit is stored. Since the fluid flow rate per unit time is corrected from the history of the fluid flow rate and pressure per time, it is possible to detect the accurate fluid flow rate even when the flow rate pulse has noise. .

[Brief description of drawings]

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

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

FIG. 3 is a block diagram showing functions of the flow rate measuring device of FIG. 1.

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

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

FIG. 6 is a diagram illustrating an example of a change over time in 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 is removed.

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

FIG. 9 is a block diagram for explaining a specific configuration of a conventional flow rate measuring device.

[Explanation of symbols]

 10 gas meter 12 gas cutoff 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)

Claims (2)

[Claims] 1. A flow rate detecting means for detecting a flow rate of a fluid and outputting a flow rate pulse per unit volume, a pressure detecting means for detecting a fluid flow rate by the flow rate detecting means and a pressure of the fluid at the same time; The fluid flow rate per unit time is calculated from the time measuring means for measuring the time interval of the flow rate pulse output from the detecting means, and the time interval of the flow rate pulse output from the flow rate detecting means and the flow rate pulse measured by the time measuring means. Calculating means for calculating, and storage means for storing the fluid flow rate per unit time calculated by the calculating means and the pressure detected by the pressure detecting means each time the flow rate detecting means detects a flow rate pulse, Fluid per unit time calculated by the calculating unit from the history of fluid flow rate and pressure per unit time stored in the storage unit Flow measuring apparatus characterized by comprising a flow rate correction means for correcting the amount. 2. The flow rate correcting means, when the fluid flow rate per unit time changes by a predetermined amount or more and when the fluctuation amount of the pressure measured at the same time is a predetermined amount or less, the fluid flow rate is regarded as noise. 2. The flow rate according to claim 1, wherein the fluid flow rate per unit time calculated by the calculation means is corrected by making a determination and approximating the flow rate detected immediately before to the fluid flow rate at that time point. measuring device.