JP3348764B2 - Gas 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 gas flow measuring device, and more particularly to a gas flow measuring device for measuring a flow rate of a gas flowing in a gas flow path.

[0002]

2. Description of the Related Art Conventionally, as a general application example of this type of apparatus, there is a gas meter for measuring the amount of LP gas or city gas used. Conventionally, as a gas meter, referred to as a membrane gas meter, two rooms each having a gas inlet and a gas outlet, a reciprocating diaphragm that separates the two rooms,
It operates according to the reciprocating motion of the diaphragm and alternately closes one of the gas inlet and the gas outlet of the room, and moves the diaphragm to the other room by the gas pressure of the gas flowing into one of the rooms, and the other one. A device having a switching valve for discharging gas in a room and a reciprocating-rotation converting mechanism for converting reciprocating motion of a diaphragm into rotational motion is generally used. In order to determine the gas usage, this film-type gas meter rotates the rotating shaft by the rotation obtained by the reciprocating-rotating mechanism, drives the integration counter, and displays the gas usage in an integrated manner.

[0003] Such a membrane-type gas meter drives an integration counter utilizing the fact that a diaphragm reciprocates according to a gas flow rate, and mechanically measures the volume of a room defined by the diaphragm. An electric signal corresponding to the gas flow rate cannot be obtained.

Therefore, an NS-magnetized magnet is attached to a rotating shaft that is rotated by the rotation obtained by the reciprocating-rotating mechanism, and a reed switch arranged close to the NS is turned on and off by the rotation of the magnet to adjust the reed switch according to the gas flow rate. There is also a method in which a flow pulse signal having a predetermined cycle is generated, and an arithmetic processing is performed using a volume per pulse, for example, 0.7 l (liter), so that the integrated flow rate can be recognized. Also, the gas flow rate (l / h or m ³ / h) can be obtained by measuring the pulse period.

[0005]

The above-mentioned membrane gas meter aims at knowing only the integrated gas amount (l or m ³ ) for a certain period of time on a daily, weekly or monthly basis from a measured value. Since it is not necessary to recognize the change in flow rate that occurs during the period in which the pulse is generated, a large volume per pulse and low resolution do not pose a significant problem.

However, when the current gas usage state is continued, it is not possible to know how much the gas usage will be during a certain period of time, for example, in hours or minutes. For this purpose, the current instantaneous flow rate (l / h or m ³
/ H) can be easily known.

In order to obtain the instantaneous flow rate, the resolution may be increased. However, as a method of increasing the resolution in the above-mentioned membrane gas meter, it is considered that the number of magnetized poles of the magnet is increased and the volume per pulse is reduced accordingly. Can be
However, there is a limit to increasing the number of poles of the magnet.

In view of the above, an encoder plate having reflection surfaces and non-reflection surfaces alternately formed on a rotating shaft rotated by reciprocating motion of a diaphragm, instead of a magnet, a light emitting element and a light receiving device arranged opposite to the encoder plate It is also conceivable to generate a pulse signal with higher resolution by using an encoder constituted by an optical sensor composed of elements. However, also in this case, the reflection surface and the non-reflection surface must be formed on the encoder plate, so that the resolution is naturally limited.

To solve the problem of the limitation of the resolution,
For example, a flow sensor described in Japanese Patent Publication No. 6-43906, which generates an electric signal whose magnitude, frequency, and the like continuously changes according to the gas flow rate, may be used. However, this type of sensor generally has a very narrow flow rate detection range that depends on the cross-sectional area of the flow path in which the sensor is installed. This is because accuracy is deteriorated even if the flow velocity is too large or small. For this reason, this type of sensor cannot be applied to a sensor whose gas flow rate changes in a wide range, such as a gas meter.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a gas flow measuring device capable of measuring a wide range of instantaneous flow in view of the above-mentioned conventional problems.

Another object of the present invention is to provide a gas flow measuring device capable of measuring an instantaneous flow rate in a wide range and measuring an integrated flow rate in view of the above-mentioned conventional problems.

Another object of the present invention is to provide a gas flow rate measuring device capable of measuring and displaying a wide range of instantaneous flow rates in view of the above-mentioned conventional problems.

It is still another object of the present invention to provide a gas flow measuring device capable of measuring an instantaneous flow rate in a wide range and measuring and displaying an integrated flow rate in view of the above-mentioned conventional problems. .

[0014]

According to a first aspect of the present invention, there is provided a gas flow measuring device, comprising: a gas inlet IN and a gas outlet OUT, as shown in FIG. Between each of which are set in advance
A plurality of gas flow paths 12A to 12C having different flow path cross-sectional areas partially overlapping each other are provided near the gas inlet of the plurality of gas flow paths, and one of the plurality of gas flow paths is provided. Flow path switching means 11 for selecting and flowing gas from the gas inlet to the gas outlet through the selected gas flow path; and a gas flowing in the gas flow path provided in each of the plurality of gas flow paths. Flow detecting means 13A to 13C for outputting a signal corresponding to the flow velocity of the gas, a signal from the flow detecting means provided in the gas flow path selected by the flow path switching means, and a flow path of the gas flow path The instantaneous flow rate calculating means 14A-1 for calculating the instantaneous flow rate based on the cross-sectional area and the flow rate detecting means provided in the gas flow path currently selected by the flow path switching means. Performed by arithmetic means When there is another gas flow path provided with the flow detecting means suitable for generating a signal corresponding to the flow rate of the gas at the instantaneous flow rate, the flow is performed so as to flow the gas through the other gas flow path. Flow path switching control means 14A-2 for outputting a switching signal to the path switching means , wherein the flow path switching control means
Therefore, the calculated instantaneous flow rate is provided in the gas flow path.
Flow detection means for each of the flow detection means
The calculated instantaneous flow rate is the highest by comparison with the output range.
Small flow rate detection range and adjacent flow rate detection range
Or within the flow rate detection range overlapping with
Large flow rate detection range and adjacent flow rate detection range
When within the flow rate detection range overlapping with
Selecting the gas flow path having a flow rate detection range,
The instantaneous flow rate is increasing and within the overlap range
The gas flow path having a large flow rate detection range.
The calculated instantaneous flow rate is decreasing and the
When it is within the multiple range, it has a small flow rate detection range.
A switching signal for selecting the gas flow path,
Is output .

[0015] In the above structure, disposed between the gas inlet IN and gas outlet OUT, the flow set in advance to each
A plurality of gas passages 12A to 12C having a part of the amount detection range overlapping each other have different passage cross-sectional areas, and the passage switching means 11 provided near the gas inlet of the plurality of gas passages. However, one of the plurality of gas flow paths is selected, and the gas flows from the gas inlet to the gas outlet through the selected gas flow path. The flow detecting means 13A to 13C provided in each of the plurality of gas flow paths output a signal corresponding to the flow velocity of the gas flowing in the gas flow path. Instantaneous flow rate calculation means 14A-1
Calculates the instantaneous flow rate based on the signal from the flow detection means provided in the gas flow path selected by the flow path switching means and the flow path cross-sectional area of the gas flow path. Flow detection means suitable for generating a signal corresponding to the gas flow rate of the instantaneous flow rate calculated by the instantaneous flow rate calculation means, rather than the flow detection means provided in the gas flow path currently selected by the flow path switching means When there is another gas flow path provided with the flow path, the flow path switching control means 14A-2 outputs a switching signal to the flow path switching means so that the gas flows through the other gas flow path. Therefore, even if the flow rate changes greatly in the plurality of gas flow paths, the flow detection means 13A to 13A to 1
An instantaneous flow rate gas suitable for the 3C to generate a signal corresponding to the flow rate of the instantaneous flow rate gas always flows. Channel
The switching control means 14A-2 is operated by the instantaneous flow rate calculating means.
The calculated instantaneous flow rate and the flow detection
Comparison with the flow rate detection range predetermined for each of the output means
, The calculated instantaneous flow rate is the smallest flow rate detected
Overlapping flow detection between the range and the adjacent flow detection range
When the flow rate is within the output range or when the flow rate is the largest
Overlapping flow detection between the range and the adjacent flow detection range
When it is within the output range, a gas with an adjacent flow rate detection range
Output a switching signal to select the flow path to the flow path switching means
I do. The flow path switching control unit 14A-2 also performs the calculated instantaneous
When the hourly flow rate is increasing and within the overlapping range,
Switching signal for selecting gas flow path with flow rate detection range
Output to the flow path switching means. Channel switching control means
14A-2 shows that the calculated instantaneous flow rate is
When the flow rate is within
The switching signal for selecting the gas flow path provided is sent to the flow path switching means.
And output.

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of a gas flow measuring device according to the present invention configured as a gas meter.

FIG. 1 shows the whole of a gas meter from a gas inlet IN to a gas outlet OUT. The gas inlet IN and the gas outlet OUT are flow paths through which a maximum flow rate of gas to be measured can be supplied. It consists of a gas passage with a cross-sectional area. The gas inlet IN is connected to a switching valve 11 composed of a plurality of electromagnetic on-off valves (not shown), and is branched via the switching valve 11 into three gas channels 12A to 12C having different channel cross-sectional areas. Assuming that the cross-sectional areas of the gas flow paths 12A to 12C are Sa to Sc, they have a relationship of Sa <Sb <Sc.

The gas flow paths 12A to 12C are provided with flow sensors 13A to 13C for outputting flow velocity signals of magnitudes corresponding to the flow velocity of the gas flowing in the gas flow paths. The flow velocity signals v1, v2, and v32 output from the flow sensors 13A to 13C are input to an arithmetic processing unit 14 including, for example, a microcomputer (μCOM), where they are converted into gas flow rates. This conversion is performed by an operation of Q = αSv based on the fact that the flow rate Q is proportional to the flow velocities v1 to v3 and the flow path cross-sectional areas Sa to Sc when the gas pressure is constant. The three gas channels 12A to 12C are:
They are brought together downstream of the flow sensors 13A to 13C and connected to the gas flow path 12.

ΜCOM constituting the arithmetic processing unit 14
Is a central processing unit (CPU) 14A that operates according to a predetermined program, and a read-only memory (ROM) 14B that stores a predetermined program and data.
In addition to a read / write memory (RAM) 14C for storing data and the like generated in the course of processing, flow rate signals from the flow sensors 13A to 13C are sampled under the control of the CPU 14A, and analog-digital Convert to C
It has an A / D converter 14D for inputting to the PU 14A. C
In addition to the display unit 15 and the selection switch 16, the PU 14A
A non-volatile memory 17 serving as an integrated flow rate holding means composed of an EEPROM capable of holding stored contents without a power supply is connected, and a result selected by the selection switch 16 is displayed on the display unit 15.

The arithmetic processing unit 14 samples the flow velocity signals from the flow sensors 13A to 13C at a predetermined cycle, converts the sampled flow velocity signals from analog to digital (A / D), reads the flow velocity signals, and reads the read flow velocity signals. Calculate the instantaneous flow rate (l / h, m ³ / h, etc.) based on the signal,
Always integrated flow rate by integrating the instantaneous flow rate (l, such as m ³⁾
Is calculated. The calculated integrated flow rate is stored and held in the form of an exponent by incrementing the counter value configured in the nonvolatile memory 17 every time the unit flow rate is integrated. When the integrated flow rate is selected by the selection switch 16, the display 1
5, the integrated flow rate is displayed, and when the instantaneous flow rate is selected, the display section 15 displays the instantaneous flow rate.

As shown in FIG. 3, the detection ranges of the flow sensors 13A to 13C are Q0 to Q1 and Q2 to Q2, respectively.
3, Q4 to Q5, and Q0 to Q5
There is a relationship of <Q2 <Q1 <Q4 <Q3 <Q5, and the flow sensors 13A and 13B and 13B and 13C partially overlap the detection range.

Then, the arithmetic processing unit 14 outputs a switching control signal to the switching valve 11 based on the measured gas flow rate, and connects one of the gas flow paths 12A to 12C to the gas inlet IN. Specifically, when the gas flow rate is increasing, the gas flow path is switched from the gas flow path 12A to the gas flow path 12B when the flow rate becomes Q2. Flow path 12B to gas flow path 12C
And outputs a switching control signal for switching to.

Conversely, when the gas flow rate is decreasing,
When the flow rate reaches Q3, the gas flow path is switched from the gas flow path 12C to the gas flow path 12B, and the gas flow rate further decreases and the flow rate becomes Q
When it becomes 1, a switching control signal for switching from the gas flow path 12B to the gas flow path 12A is output. As described above, by giving hysteresis to the control for switching the gas flow path when the gas flow rate increases and when the gas flow rate decreases, chattering of the switching operation due to the flow rate variation can be prevented.

As the flow sensor, the above-mentioned Japanese Patent Publication No.
4 to 6 described in JP-A-43906 can be applied. That is, as shown in FIG. 4, a through hole 4 communicating the left and right openings 2 and 3 is formed at the center of the semiconductor substrate 1 by anisotropic etching. A bridge portion 5 is formed, which is spatially isolated from the base 1 like a bridge, and is consequently thermally insulated from the semiconductor base 1. On the surface of the bridging portion 5, a thin-film heater element 7 and thin-film temperature-measuring resistance elements 8, 9 sandwiching the heater element 7 are formed in an array. A thin-film temperature measuring resistance element 10 is formed at a corner of the semiconductor base 1. Reference numeral 6 denotes a protective film made of a material having low thermal conductivity.

The operation will be described with reference to FIGS. 5 (a) and 5 (b) showing the cross section and the temperature distribution. The heater element 7 is set to a certain temperature th5, th6 higher than the ambient temperature.
(For example, 63 ° C .: ambient temperature reference), the temperatures t 6 and t 7 (for example, 3
5 ° C .: ambient temperature reference) is the temperature t of the heater element 7 as shown in FIG.
It is substantially symmetric about h5 and th6. At this time, FIG.
When the gas moves in the direction of arrow 11, the temperature measuring resistance element 8 on the upstream side is cooled and its temperature is decreased by ΔT6. On the other hand, in the temperature measuring resistance element 9 on the downstream side, heat conduction from the heater element 7 is promoted by using a gas flow as a medium, and the temperature rises by ΔT7, so that a temperature difference occurs. Therefore, by incorporating the heater elements 8 and 9 into the Wheatstone bridge circuit, the temperature difference can be converted into a voltage, a voltage output corresponding to the flow velocity can be obtained, and the flow velocity of the gas can be detected as shown in FIG. .

As another flow sensor, there is a fluid flow sensor utilizing the fact that the frequency of occurrence of Karman vortex is proportional to the flow velocity. In the case of this flow sensor, the frequency is converted into a voltage and the flow rate is changed according to the flow velocity. Voltage output is obtained, and the flow velocity of the gas can be detected. However, even in the case of this sensor, the flow velocity cannot be detected accurately even if the flow velocity is too large or too small, and the flow rate range that can be detected by one sensor is limited.

Hereinafter, μC constituting the arithmetic processing unit 14 will be described.
The operation will be described in detail with reference to the flowchart of FIG. 7 showing the processing performed by the CPU 14A in the OM. In the figure, the CPU 14A starts the operation by turning on the power, waits for the elapse of a predetermined sampling cycle time in the first step S1, and when the sampling time elapses and the determination in step S1 becomes YES, the step S1 is started.
Proceed to 2. In step S2, the current gas inlet I
The flow rate signals from the flow sensors 13A to 13C provided in the gas flow paths 12A to 12C that communicate the gas with the N and the gas outlet OUT are read and read via the A / D converter 14D. Based on the flow rate signal from the flow sensor, the flow rate Qn is calculated by the above equation Q = αSv, and the process proceeds to step S3. The current gas inlet IN
And the gas outlet OUT communicates with the gas outlet OUT.
By switching the switching valve 11 in accordance with a switching control signal from the CPU 14A, a selection is made from among the gas flow paths 12A to 12C.

In step S3, an integrated flow rate process for integrating the flow rate Qn calculated in step S2 is performed, and then the process proceeds to step S4. In step S4,
The calculation result of step S2 is stored in the current flow rate Qn storage area formed in a predetermined area in the RAM 14C, and the flow rate Qn-1 previously stored in the current flow rate Qn storage area is stored in a predetermined area in the RAM 14C. Step S5 after storing in the flow rate Qn-1 storage area
Proceed to.

In step S5, it is determined whether or not the gas flow path selected to flow gas by the switching valve 11 is the gas flow path 12A. If the determination in step S5 is YES, the flow proceeds to step S6. Then, the flow rate Qn calculated in step S2 becomes equal to the predetermined flow rate value Q.
It is determined whether it is less than 2. Immediately when the determination in step S6 is YES, and when the determination is NO, the process proceeds to step S7, in which a switching control signal for switching the gas flow path through which the gas flows from 12A to the gas flow path 12B is output to the switching valve 11, and Proceed to S8.

The flow advances to step S8 to determine whether the selection switch 16 has selected the instantaneous flow rate or the integrated flow rate. If the instantaneous flow rate has been selected, the flow advances to step S9 to store the current flow rate Qn storage area in step S4. The current flow rate Qn stored in the display unit 15 is used as the instantaneous flow rate.
And then returns to step S1. on the other hand,
When the integrated flow rate is selected, the process proceeds to step S10, and the value stored in the integrated flow rate counter provided in the nonvolatile memory 17 obtained in the integrated flow rate processing described later in detail in step S3 is displayed as the integrated flow rate. After outputting to the unit 15, the process returns to the step S1.

When the determination in step S5 is NO, that is, when the gas flow path selected to flow the gas by the switching valve 11 is not the gas flow path 12A, the process proceeds to step S11, where the switching valve 11 controls the gas flow. It is determined whether or not the gas flow path selected to flow is the gas flow path 12B. If the determination in step S11 is YES, the process proceeds to step S12, and the flow rate Qn calculated in step S2 is the previous flow rate. It is determined whether or not the flow rate Qn-1 stored in the Qn-1 storage area is exceeded. When the determination in step S12 is N0, that is,
When the flow rate Qn measured this time does not exceed the flow rate Qn-1 measured last time, and the gas flow rate does not change or is decreasing, the process proceeds to step S13.

In step S13, the flow rate Qn calculated in step S2 is equal to the predetermined flow rate value Q1.
It is determined whether it is less than. Immediately when the determination in step S13 is N0, and when the determination is YES, the process proceeds to step S14, in which a switching control signal for switching the gas flow path through which the gas flows from 12B to the gas flow path 12A is output to the switching valve 11, and Proceed to step S8.

When the determination in step S12 is YES, that is, when the flow rate Qn calculated in step S2 exceeds the flow rate Qn-1 stored in the previous flow rate Qn-1 storage area, the gas flow rate increases. If there is a tendency, the process proceeds to step S15, and it is determined whether or not the flow rate Qn calculated in step S2 is less than a predetermined flow rate value Q4. When the determination in step S13 is YES, immediately, when the determination is N0, the process proceeds to step S16 to change the gas flow path through which the gas flows from 12B to the gas flow path 12C.
Is output to the switching valve 11, and the process proceeds to step S8.

When the determination in step S11 is NO,
That is, when the gas flow path selected to flow the gas by the replacement valve 11 is the gas flow path 12C, the process proceeds to step S17, and the flow rate Qn calculated in step S2 is stored in the previous flow rate Qn-1 storage area. It is determined whether the flow rate is equal to or more than the flow rate Qn-1. Step S
When the determination in Step 17 is YES, the above step S8 is immediately performed.
Proceed to. When the determination in step S17 is NO, that is, when the flow rate Qn measured this time is less than the flow rate Qn-1 measured last time and the gas flow rate is decreasing, the process proceeds to step S18.

In step S18, step S18
It is determined whether the flow rate Qn calculated in step 2 is less than a predetermined flow rate value Q3. Immediately when the determination in step S118 is N0, and when the determination is YES, the process proceeds to step S119, in which a switching control signal for switching the gas flow path through which the gas flows from 12C to the gas flow path 12B is output to the switching valve 11, and Proceed to step S8.

As is clear from the description given above with reference to the flowchart, the CPU 14A determines the signals from the flow sensors 13A to 13C provided in the gas passages 12A to 12C selected by the switching valve 11 and the signals from the flow sensors 13A to 13C. In addition to acting as an instantaneous flow rate calculating means 14A-1 for calculating the instantaneous flow rate based on the flow path cross-sectional area of the flow path, the flow sensors 13A to 13A suitable for generating a signal corresponding to the flow rate of the calculated instantaneous flow rate gas are provided. When there is another gas flow path provided with 13C, it functions as flow path switching control means 14A-2 that outputs a switching signal to the switching valve 11 so that gas flows through the other gas flow path.

C serving as flow path switching control means 14A-2
The PU 14A selects the current flow rate by comparing the instantaneous flow rate calculated by the instantaneous flow rate calculation means 14A-1 with a flow rate detection range predetermined for each of the flow sensors 13A to 13C provided in the gas flow paths 12A to 12C. A flow sensor 13A suitable for generating a signal corresponding to the flow rate of the calculated instantaneous flow rate gas is determined based on the determination result as to whether the calculated gas flow path is suitable for flowing the calculated instantaneous flow rate gas. It is determined whether there is another gas flow path provided with .about.13C.

C serving as channel switching control means 14A-2
The PU 14A also determines whether or not the calculated instantaneous flow is suitable for flowing the gas at the calculated instantaneous flow rate when the calculated instantaneous flow rate is within the overlapped flow rate detection range. It is determined whether there is another gas flow path provided with the flow sensors 13A to 13C suitable for generating a signal corresponding to the above.

C serving as flow path switching control means 14A-2
Further, the PU 14A is further configured such that when the calculated instantaneous flow rate is within the flow rate detection range where the flow rate detection range with the smallest flow rate and the flow rate detection range adjacent thereto are overlapped, or the flow rate detection range with the largest flow rate and the flow rate detection range adjacent thereto. When the flow rate detection range overlaps with the flow rate detection range, select a gas flow path with an adjacent flow rate detection range, and when the calculated instantaneous flow rate is increasing and within the overlap range, the flow rate of the large flow rate When a gas flow path having a detection range is selected and the calculated instantaneous flow rate is in a decreasing trend and within the overlapping range, a switching signal for selecting a gas flow path having a flow rate detection range with a small flow rate is sent to the switching valve 11. Output to

The flow rate integration process in step S3 will be described with reference to a flowchart of FIG. 8 showing a specific example. First, in the first step S3a, the flow rate Qn calculated in step S2 is formed in the RAM 14C. It is added to the value Qx in the flow rate accumulation area. Next, in step S3b, it is determined whether or not the value Qx in the flow rate integration area has become equal to or greater than the unit volume Q0.
In the case of, the process returns to step S4 of the main flowchart. When the determination in step S3b is YES, the process proceeds to step S3c and is added to the value Qx in the flow rate integration area. Next, the process proceeds to step S3b, in which -Q0 is subtracted from Qx by adding -Q0 to the value Qx in the flow rate accumulation area, and then proceeds to step S3d, where the integrated flow counter formed in the nonvolatile memory 17 is incremented. Then, the process returns to step S4 of the main flowchart.

As is clear from the description given above with reference to the flowchart, the CPU 14a determines that the instantaneous flow rate calculating means 14A-1 is provided in the gas flow channels 12A to 12C selected by the switching valve 11 in the flow sensor 13A. ~
An integrated flow rate calculating means 14A-3 which reads the signal from 13C at a predetermined cycle, integrates the calculated instantaneous flow rate, and calculates the integrated value of the gas flow rate based on the integrated instantaneous flow rate and cycle.
Work as

Since the value of Qx is obtained by adding the instantaneous flow rate Qn obtained at each sampling period of ΔT as shown in the graph of FIG. 9, the value of Q0 is calculated by comparing the known sampling period ΔT × Qx with, for example, 0.1. Q that becomes l (liter)
Set to the value of x. Note that the shaded portions in the graph represent errors, but the polarities of the errors at the time of increasing the flow rate and at the time of decreasing the flow rate are reversed and cancel each other, so that the overall value is not so large.

The gas flow measuring device of the present invention described above measures an instantaneous flow rate that changes over a wide range, and
For example, as shown in FIG. 10, a heating gas combustor can be used for a controller that performs combustion control according to a set temperature by gas flow control instead of on / off control.

That is, the controller is disposed at a gas inlet of a combustor (not shown), and the gas flow measuring device 10 of the present invention built in the controller measures an instantaneous flow rate that changes over a wide range. The instantaneous flow signal from the gas flow measurement device 10 is input to the opening degree calculation unit 30 to which the set flow signal from the flow setting unit 20 is input. Opening degree calculation unit 30
Compares the instantaneous flow rate signal and the set flow rate signal, outputs an opening degree signal corresponding to the magnitude of the difference between the two, and outputs the opening degree signal from a proportional control valve disposed on the upstream side of the gas flow rate measuring device 10. It is supplied to the valve 40 to control the opening of the flow control valve 40.
The flow rate setting section 20 compares the set temperature set by the temperature setting device 50 with the temperature detected by the temperature sensor 60, and generates a set flow rate signal having a magnitude corresponding to the magnitude of the difference between the two.

As described above, when the difference between the temperature set by the temperature setting device 50 and the actual temperature detected by the temperature sensor 60 is large, the flow rate setting section 20 outputs a flow rate setting signal corresponding to the magnitude. The opening degree calculation unit 30 to which the flow rate setting signal is input compares the flow rate setting signal with an instantaneous flow rate signal corresponding to the current gas flow rate input from the gas flow rate measuring device 10. The output opening signal is continuously output thereafter. When the flow rate setting signal is greater than the instantaneous flow rate signal, the opening degree signal corresponding to the current opening degree of the flow control valve 40 is increased. On the contrary, the flow rate setting signal is smaller than the instantaneous flow rate signal. When there is a signal relationship, an opening signal corresponding to the current opening degree of the flow control valve 40 is output to reduce the opening degree. As a result, it becomes possible to perform combustion control according to the set temperature of the gas combustor for heating by gas flow rate control, and it is possible to perform excellent control of temperature control quality and combustion efficiency as compared with on / off control. .

In the above embodiment, when the integrated flow rate is selected by the selection switch 16, the integrated flow rate is displayed on the display unit 15, and when the instantaneous flow rate is selected, the instantaneous flow rate is displayed on the display unit 15. Although the display is performed, the selection switch 16 may be omitted, and both the integrated flow rate and the instantaneous flow rate may be displayed on the display unit 15 at the same time. Without displaying the integrated flow rate and instantaneous flow rate,
It may be used for various controls, or may be notified to a remote location by a communication line.

[0059]

As described above, according to the first aspect of the present invention, a portion of the flow rate detection range which is provided between the gas inlet IN and the gas outlet OUT is set in advance.
Selects one of a plurality of gas flow paths having different flow path cross-sectional areas overlapping each other to flow gas from a gas inlet to a gas outlet, and the flow rate of the gas flowing through this one gas flow path The instantaneous flow rate is calculated based on the corresponding signal and the flow path cross-sectional area of the gas flow path, and there is another gas flow path suitable for generating a signal corresponding to the calculated flow rate of the gas at the instantaneous flow rate. At this time, since the other gas flow path is selected to flow the gas, even if the flow rate greatly changes, a plurality of gases suitable for generating a signal corresponding to the instantaneous flow rate of the gas flow rate are provided. Since the gas always flows through one of the gas flow paths, a wide range of instantaneous flow rate can be measured. Calculated instantaneous flow rate
And a comparison with a predetermined flow rate detection range.
The flow rate detection range where the instantaneous flow rate is the smallest and adjacent to it
Is within the flow rate detection range that overlaps the
Or the flow rate detection range with the largest flow rate and adjacent to it
Is within the flow rate detection range that overlaps the
Select a gas flow path with an adjacent flow detection range
The calculated instantaneous flow rate is increasing and is within the overlap range.
Gas flow path with a large flow rate detection range
And the calculated instantaneous flow rate is decreasing and the overlap range
Within a gas flow rate with a small flow rate detection range.
The flow path changes because the flow path is selected.
Also eliminates unnecessary judgment and switching operation, and
Gas whose flow rate is within the predetermined flow rate detection range
Flow through the gas flow path at all times,
Generates a signal corresponding to the instantaneous flow rate of the gas.
So that the appropriate gas always flows through one of the gas flow paths
And the instantaneous flow rate in a wide range can be measured.

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a gas flow measuring device according to the present invention.

FIG. 2 is a block diagram showing one embodiment of a gas flow measuring device according to the present invention.

FIG. 3 is a view showing a flow rate detection range of a flow sensor provided in each gas flow path in FIG. 2;

FIG. 4 is a perspective view showing an example of a flow sensor in FIG.

5 is a diagram showing a cross section and a temperature distribution of the flow sensor of FIG.

6 is a graph showing a flow velocity-output characteristic of the flow sensor of FIG.

FIG. 7 is a flowchart illustrating a process performed by a CPU in FIG. 2;

FIG. 8 is a flowchart showing details of a process in FIG. 7;

FIG. 9 is a graph for explaining the contents of the processing in FIG. 8;

FIG. 10 is a block diagram showing an application example of the gas flow measurement device according to the present invention.

[Explanation of symbols]

IN Gas inlet OUT Gas outlet 11 Flow path switching means (switching valve) 12A to 12C Gas flow path 13A to 13C Flow detection means (flow sensor) 14A-1 Instantaneous flow rate calculation means (CPU) 14A-2 Flow path switching control Means (CPU) 14A-3 Cumulative flow rate calculating means (CPU) 15 Display means (display unit) 17 Cumulative flow rate holding means (Non-volatile memory)

Continuation of the front page (56) References JP-A-8-1559839 (JP, A) JP-A-8-75511 (JP, A) JP-A-8-136315 (JP, A) JP-A-2-93716 (JP) , U) Japanese Utility Model Showa 60-29231 (JP, U) Japanese Patent Publication No. 6-103199 (JP, B2) Japanese Patent Publication No. 62-35605 (JP, B1) Japanese Patent Publication No. 61-52409 (JP, B1) 6-35139 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 7/00 G01F 15/075

Claims (1)

(57) [Claims] 1. A method according to claim 1, wherein a portion of a flow rate detection range which is provided between a gas inlet and a gas outlet is set in advance.
A plurality of overlapping gas flow paths having different cross-sectional areas; a plurality of gas flow paths provided near the gas inlet of the plurality of gas flow paths; selecting one of the plurality of gas flow paths; Flow path switching means for causing gas to flow from the gas inlet to the gas outlet through a gas passage provided in each of the plurality of gas passages, and outputting a signal corresponding to a flow rate of the gas flowing in the gas passage. A flow detecting means, an instant that calculates an instantaneous flow rate based on a signal from the flow detecting means provided in the gas flow path selected by the flow path switching means and a flow path cross-sectional area of the gas flow path. A signal corresponding to the flow rate of the gas at the instantaneous flow rate calculated by the instantaneous flow rate calculation means, from the flow rate calculation means and the flow detection means provided in the gas flow path currently selected by the flow path switching means. Suitable to produce before When there is another gas flow path provided with the flow detection means, a flow path switching control means for outputting a switching signal to the flow path switching means so as to flow gas through the other gas flow path; The channel cut
Change control means calculated by the instantaneous flow rate calculation means.
An instantaneous flow rate and the flow detection provided in the gas flow path.
Comparison with the flow rate detection range predetermined for each of the output means
By the above, the calculated instantaneous flow rate is the smallest flow rate
Overlapping flow between the detection range and the adjacent flow detection range
When the flow rate is within the detection range or when the flow rate is the largest
Overlapping flow between the detection range and the adjacent flow detection range
When within the volume detection range, the adjacent flow rate detection range
The selected gas flow path is selected, and the calculated instantaneous flow rate is
Large flow rate when increasing and within the overlap range
The gas flow path having a flow rate detection range of
The calculated instantaneous flow rate is decreasing and within the overlap range
When the gas flow path has a small flow detection range
Output to the flow path switching means.
Gas flow measuring device, characterized in that that.