JP2002328054A - Method for measuring gas flow and gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas meter with a safety function to accurately measure a flow in a short time. SOLUTION: A crank shaft 39 is interlocked with a rubber diaphragm 21A and rotates. Twenty magnetic poles in an outer circumference of a circular magnet attached to a lower end of the crank shaft 39 act on a magnetic sensor 47 and output twenty flow pulses per rotation of the crank shaft. A constant flow flows in the gas meter. Intervals T1 -T20 and pulse numbers are concurrently measured. A correspondence table of the pulse numbers and pulse width ratios 20.Tn/ΣTn is stored in a memory. The pulse numbers are continuously counted. An unknown flow Q is calculated from the pulse interval T when the unknown flow flows, the pulse width ratio Pn corresponding to the pulse number in the table and a volume K of a measuring chamber per rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas flow measuring method and a gas meter used for measuring city gas and the like.

[0002]

2. Description of the Related Art A membrane gas meter constantly monitors a gas flow rate by a built-in microcomputer, and when a flow rate abnormality (excessive use) or abnormal use of gas for a long time occurs, a shut-off valve is automatically closed to supply gas. If the flow rate is stopped or a minute flow rate is detected continuously for 30 days or more, it is determined that there is gas leakage from the gas pipe etc. downstream of the gas meter, and a safety function such as turning on the LED and displaying an alarm is provided. ing.

In FIG. 7, a gas flowing from an inlet 2 of a gas meter 1 as shown by an arrow is measured by a measuring mechanism 3 and output from an outlet 4.
Spill out of. A flow sensor 7 composed of a reed switch which is turned on / off by the movement of a magnet 6 attached to a small elbow 5 of the measuring mechanism 3 is provided with a pulse signal (hereinafter referred to as a flow pulse) for each volume of the measuring chamber, that is, for each rotation of the meter. Say)
Put out. The interval (cycle) of the flow pulse is monitored by the microcomputer 9 mounted on the printed circuit board 8. Microcomputer 9
Various abnormal use states during gas use are programmed, and when an abnormal use of gas such as an abnormal flow rate occurs, the microcomputer judges and shuts off the shutoff valve 10 to shut off the gas. Further, when the seismic sensor 11 built in the meter detects a large earthquake, when the pressure sensor 12 detects an abnormal decrease in the supply pressure, or when an external signal 1 from a gas leak alarm or the like is detected.
3 also closes the shut-off valve 10 to prevent the danger of a gas accident. 14 is a red LED for displaying an alarm, 15 is a test switch for checking the operation of the shut-off valve 10, and 16 is a battery for operating an electronic circuit such as a microcomputer.

When the shutoff valve 10 is closed and the gas supply is stopped, the return button 1 is used to restart the gas supply.
7 is manually operated, and the shutoff valve 10 is opened by pushing rightward in the figure.
Return. The microcomputer 9 monitors whether or not gas flows when the shut-off valve 10 is opened / returned.
When the gas flows during two minutes (that is, when a flow pulse is generated), a shut-off function for automatically re-closing the shut-off valve on the assumption that there is a gas leak downstream of the meter is also provided. In this way, the shut-off function based on the leak at the time of return of the shut-off valve prevents the release of raw gas at the time of return of the shut-off valve, thereby avoiding danger.

FIGS. 8 to 12 show a weighing mechanism for generating a flow pulse by turning on / off a flow sensor 7 composed of a reed switch every rotation of the meter. As shown in FIG. 10, the inside of the housing 18 of the gas meter is
A, 20B. For example, regarding the room 20A, a film plate 22A is provided on the inner wall of the housing 18 via a rubber film 21A. One end (left end in the figure) of the wing 25A is connected to the membrane plate 22A via a hinge base 23A and a pin 24A, and the other end of the wing 25A is fixed to a wing shaft 26A rotatably provided on the housing 18. . When the gas flows, the membrane plate 22
A reciprocates in the directions of arrows G1 and G2, and in conjunction therewith, the blade 25A swings in the directions of arrows H1 and H2, and the blade shaft 26A reciprocates. The configuration of the room 20B is the same as that of the room 20A.

As shown in FIGS. 8, 9 and 12, large elbows 27A and 27B are provided at the upper ends of the blade shafts 26A and 26B, respectively.
7B is fixed at one end, and the other ends of the large elbows 27A and 27B are connected to the small elbows 2 via pins 28A and 28B, respectively.
9A and 29B are connected to the right ends of the figures. The other ends (left ends in the drawing) of the elbows 29A and 29B are loosely connected to pins 31 implanted in the adjustment plate 30. Adjustment plate 30
The upper end of the shaft 33 implanted in the crank arm 32 is inserted into the hole 30a (see FIG. 12) and fixed by caulking. One end (right end in the figure) of each of the crank rods 34A and 34B is loosely connected to the shaft 33. The other ends of the crank rods 34A and 34B are pins 35A and 3 respectively.
It is connected to valves 36A and 36B via 5B.
Valves 36A and 36B are shafts 37A erected on the housing 18.
And 37B. The right end of the crank arm 32 is shown in FIGS.
As shown in the figure, the crankshaft 39 is fixed to the upper end of a crankshaft 39 rotatably supported by the crankshaft 38. The small elbow 29B corresponds to the small elbow 5 in FIG.

A worm 40 is fitted on the crankshaft 39 and meshes with a worm wheel 41. As shown in FIG. 9, a bent rod portion 41b is formed at one end of a shaft 41a of the worm wheel 41, and engages with a hook 42 to transmit the rotation of the worm wheel 41. The hook 42 transmits the rotation of the crankshaft 39 via a gear mechanism 43 to a display unit 44 composed of a numeral wheel for displaying the gas usage.

When the gas flows, the reciprocating rotation of the blade shafts 26A and 26B causes the large elbows 27A and 27B to swing, and this movement is caused by the small elbows 29A and 29B, the adjustment plate 30, the shaft 33,
The crankshaft 39 is rotated via the crank arm 32. One revolution of the crankshaft 39 corresponds to the first rotation of the gas meter.
Rotation. The valves 36A and 36B swing open and close in conjunction with these movements.

[0009]

In the above prior art,
In order to achieve the safety function, the microcomputer monitors a flow rate pulse generated every one rotation of the meter, and recognizes and measures the gas flow rate. The volume of gas flowing per one rotation of the meter is the volume of the metering chamber of the meter, and is set to a predetermined value for each number of the meter. For example, in the case of the No. 15 meter, since the volume of the measuring chamber is 4 [L / rev], the next flow pulse is not generated unless 4 [L] flows. Therefore, as a gas meter with a safety function, it takes at least the time interval of the flow pulse to determine the abnormal use of gas.
It takes a long time to determine the cutoff at the time of the abnormal flow rate, and there is a demand to further reduce the determination time. There is also a demand for further shortening the time of 2 minutes for leak detection at the time of return from shutdown.

In order to realize such a shortening of the time, instead of generating a flow pulse by the movement of a magnet attached to a small elbow which makes one reciprocation per rotation of the meter, the meter rotates in conjunction with the small elbow. It is conceivable to attach a multi-pole circular magnet to the crankshaft and generate a flow pulse for each magnetic pole of the circular magnet by a rotation sensor arranged in proximity to the circular magnet. Thus, for example, if 20 flow pulses are generated per rotation of the crankshaft, it seems as if the flow pulses are obtained at 1/20 intervals (period) of the prior art. However, even when the gas flow rate does not fluctuate and the gas flow rate is constant, the rotation of the crankshaft is unequal speed, and the angular velocity changes during one rotation. There is a fold difference. Therefore, there is a problem that a large measurement error occurs in the flow rate measured in this way, and it cannot be put to practical use as it is.

Accordingly, an object of the present invention is to provide a gas flow measuring method and a gas meter capable of solving such a problem and accurately measuring a gas flow in a short time.

[0012]

In order to achieve the above object, a first aspect of the present invention is a rotation detecting apparatus which generates a plurality of flow rate pulses per rotation of a crankshaft which rotates in conjunction with a reciprocating movement of a rubber film. With a membrane gas meter provided with means, A constant flow rate Q ₀ is supplied, and the pulse No.
n and its pulse No. 1. a table creation mode for creating a correspondence table of numerical values corresponding to the ratio Tn / ΔTn between the pulse width Tn of the flow rate pulse and ΔTn; The pulse width T and the pulse No. of the flow pulse when the unknown flow Q flows. 2. This pulse No. Of the pulse No. in the correspondence table. 3. Read the numerical value corresponding to the ratio Tn / ΣTn corresponding to from the correspondence table; A gas flow measuring method comprising a measurement mode for calculating an unknown flow rate Q from this numerical value and the pulse width T.

According to a second aspect of the present invention, there is provided a film-type gas meter provided with rotation detecting means for generating a plurality of flow pulses per rotation of a crankshaft which rotates in conjunction with the reciprocating movement of a rubber film. A constant flow rate Q ₀ is supplied, and the pulse No.
n and its pulse No. 1. a table creation mode for creating a correspondence table of numerical values corresponding to the ratio Tn / ΔTn between the pulse width Tn of the flow rate pulse and ΔTn; The pulse width T and the pulse No. of the flow pulse when the unknown flow Q flows. 2. This pulse No. Of the pulse No. in the correspondence table. 3. Read the numerical value corresponding to the ratio Tn / ΣTn corresponding to from the correspondence table; A gas flow measurement method comprising: a measurement mode for calculating a true pulse width T ′ corresponding to an unknown flow rate Q from the numerical value and the pulse width T.

[0014] The invention according to claim 3, a rotation detecting means for generating a plurality of flow pulses per one rotation of the crank shaft to rotate in conjunction with the reciprocating movement of the rubber film, when a current of a constant flow rate Q _0, flow rate Pulse No. of the pulse Pulse N for counting n
o. A counter for measuring a pulse width Tn of each flow pulse; n, pulse width Tn and ΔTn
Table creating means for creating a correspondence table with a numerical value corresponding to the ratio Tn / ΣTn to the table, storage means for storing the correspondence table, and a pulse No. when an unknown flow rate Q flows. And the pulse width T, respectively. Pulse No. obtained by measuring with a counter and a timer. Is read from a correspondence table of the storage means, and a calculating means for calculating an unknown flow rate Q from the numerical value and the pulse width T is provided. .

[0015] The invention according to claim 4, a rotation detecting means for generating a plurality of flow pulses per one rotation of the crank shaft to rotate in conjunction with the reciprocating movement of the rubber film, when a current of a constant flow rate Q _0, flow rate Pulse No. of the pulse Pulse N for counting n
o. A counter for measuring a pulse width Tn of each flow pulse; n, pulse width Tn and ΔTn
Table creating means for creating a correspondence table with a numerical value corresponding to the ratio Tn / ΣTn to the table, storage means for storing the correspondence table, and a pulse No. when an unknown flow rate Q flows. And the pulse width T, respectively. Pulse No. obtained by measuring with a counter and a timer. And a calculating means for reading a numerical value corresponding to the ratio Tn / ΣTn corresponding to the above from the correspondence table of the storage means and calculating a true pulse width T ′ corresponding to the unknown flow rate Q from the numerical value and the pulse width T. It is a gas meter characterized by comprising:

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described with reference to some examples.

FIG. 1B is a perspective view of the gas meter according to the first embodiment with the upper case removed.
FIG. 2A is an exploded perspective view of a part of FIG. The measuring mechanism shown in FIGS. 1A and 1B has a structure in which the crankshaft makes one rotation for each reciprocation of the rubber film in conjunction with the reciprocating movement of the rubber film. The same portions are denoted by the same reference numerals and description thereof will be omitted.

In the first embodiment, a crankshaft 39 is extended downward instead of a reed switch as a flow sensor provided on a small elbow 29a, and a multi-pole circular magnet 46 is provided at the lower end thereof. And a rotation detecting means 48 comprising a magnetic sensor 47 disposed close to the outer periphery of the circular magnet. The outer periphery of the circular magnet 46 is magnetized to 20 poles at equal intervals. Then, the magnetic pole is detected by the magnetic sensor 47 to generate an electric signal (flow rate pulse). Magnetic sensor 47
Is composed of, for example, a ferromagnetic magnetoresistive element and a Schmitt trigger circuit that shapes the output and converts it into a rectangular pulse signal, and functions as a flow sensor.

The magnetic sensor 47 as a flow sensor is
Per revolution of the rank shaft 39 (ie, per reciprocation of the rubber film)
Generates 20 flow pulses, but turns the crankshaft 39
In the rotation, the angular velocity is not constant during one rotation but fluctuates.
You. Therefore, even when flowing a constant flow rate that does not fluctuate,
The period (interval) of the flow pulse is not constant and varies. K
During the time A of one rotation of the rank axis, the pulse No. From 1
Lus No. 20 flow pulses up to 20 as shown in FIG.
Occurs. T₁, T_Two, T_Three, ..., Tn, ..., T₂₀Is
This corresponds to the cycle (interval) of each flow pulse. Note that these
T₁, ..., T₂₀Is hereinafter referred to as a pulse width. The pulse width is
Usually, the time indicated by the symbol τ in FIG. 2 is usually expressed.
However, here, the period (interval) T₁, T_Two, T_Three, ..., T
n, ..., T ₂₀Is called a pulse width.

[0020] when a current of constant flow rate, the pulse width _{T 1, T 2, T 3} , ..., Tn, ..., shown in FIG. 3 or T ₂₀ is how to change. FIG. 3 shows the pulse numbers on the horizontal axis.
The pulse width ratio Pn or Pn / 20 is graduated on the vertical axis. The pulse width ratio Pn is a ratio of the pulse width Tn to A / 20, and is represented by Pn = Tn / (A / 20).

[0021] Time A for one rotation of the crankshaft, a pulse width _{T 1, T 2, T 3} , ..., Tn, ..., the sum of the _{T 20, A = A 1 +} A 2 + ... An + ... + A 20 = ΣTn. Therefore, Pn can be expressed as Pn = 20Tn / ΣTn. In FIG. 3, the pulse width ratio Pn corresponds to the pulse No. 2 and a minimum of 0.72, pulse no. 13, the maximum is 1.61, and the ratio between the maximum and the minimum is 1.61 / 0.7.
At 2 = 2.2, there is almost twice as much difference. Therefore, as described above, when a plurality of flow pulses are generated in one rotation of the crankshaft, the correspondence between the pulse width and the flow rate is lost due to the uneven rotation of the crankshaft, and the pulse widths T ₁ , T ₂ , T
_3, ..., Tn, ..., in T _20, it is not possible to measure the immediate flow rate.

Therefore, in the first embodiment, a constant flow Q ₀ is supplied to the gas meter measuring mechanism shown in FIG. 1, and the pulse width of the flow pulse at that time is measured first. It has been experimentally confirmed that the pulse width ratio Pn in FIG. 3 has the same value at any flow rate if there is no fluctuation in the flow rate. Therefore, the constant flow rate Q ₀ is convenient in a gas meter production line. The flow rate may be determined.

The constant flow rate Q ₀ is supplied, and pulse Nos. And each pulse No. Pulse width _{T 1, T 2, T 3} , ..., Tn, per ..., the T ₂₀ was measured by the timer 50, create the following Table 1, is stored in the memory of the microcomputer 49. Pulse No. Is the pulse No. It counts using the counter 51.

[0024]

[Table 1]

At the time when this Table 1 is completed, T ₁ ,
..., to create a Table 2 using the T _20. At this point, Table 1 is no longer needed. 52 is a table creation means, and 53 is a table of Table 2 stored in the memory.

[0026]

[Table 2]

At this point, the microcomputer 49 changes from the table creation mode to the normal measurement mode.

Next, the operation when the unknown flow rate Q is applied will be described mainly with reference to FIGS. Microcomputer 4
When a transition from the table creation mode to the normal measurement mode is made, a pulse interrupt is applied to the microcomputer 49 at the rising edge of the flow rate pulse from the magnetic sensor. The pulse width (period) T is obtained. The timer 50 measures the pulse width T by counting up the reference clock. Pulse No. Continue from the table creation mode, and the pulse No. No. 1 to No. 20, no. 1 to No. 2
Repeated as 0, the microcomputer always recognizes. Thus, the number of the next flow pulse is always recognized.

Next, in step 61, the timer is reset, and the process proceeds to the next pulse width (cycle) measurement. In step 62, the pulse No. The pulse width ratio Pn indicated by the counter is read out from the table 53, and the pulse N
o. The content of the counter is incremented by one. In step 64, the pulse No. Judge whether the value of the counter has reached 21 and YES
In the case of pulse no. The value of the counter is set to 1 (step 65), and the flow proceeds to the flow rate calculation of step 66. Also, when the determination in step 64 is NO, the flow proceeds to flow rate calculation in step 66. In the flow rate calculation of step 66, step 60
The unknown flow rate Q is obtained from the pulse width T read in step (2) and the pulse width ratio Pn read in step 62 by Q = (K / 2
0) · (Pn / T). Here, K is the volume of the measuring chamber per one revolution of the crankshaft, and is 4 [L] for the No. 15 meter as described above. In FIG. 4A, reference numeral 54 denotes an operation means.

By the way, the pulse No. The counter 51
When an interrupt occurs at the rising edge of the flow rate pulse, the pulse width ratio Pn is read in step 62, and immediately thereafter, the value is incremented by 1 in step 63, and the pulse No. of the next pulse is read. (FIG. 4B).

In this way, the microcomputer 49 is set to the table creation mode by flowing the constant flow rate Q ₀ in the final line in the gas meter manufacturing stage, and the pulse No. of the flow rate pulse during one rotation of the crankshaft. And a table 53 of the pulse width ratio Pn. Pulse No. No. continues without interruption. 1 to No. 20, no. 1 to N
o. Continued with 20. When the table 53 is created, the mode shifts to a normal measurement mode, and the pulse width T is measured as described above. , The corresponding pulse width ratio is read out, and the unknown flow rate Q is calculated.

Incidentally, if the crankshaft rotates at a constant speed, the unknown flow rate Q can be simply calculated from the pulse width T as Q = (K / 20) / T. Since the movement of the rubber film is transmitted to the crankshaft via the link mechanism, large fluctuations in the angular velocity of the crankshaft are inevitable. By calculating, accurate flow rate measurement can be performed in a short time.

In this manner, the pulse interval of the flow rate pulse from the magnetic sensor 47 and the pulse No. stored in the table 53 are set. The flow rate Q calculated from the correspondence table between the pulse width ratio and the metering chamber volume per one rotation of the meter is used for the safety function of the gas meter. The amount of gas used as a reference for calculating the gas fee is displayed on the display unit 44 composed of a numeral wheel which is rotated and displayed via the hook 42 engaged with the worm wheel shaft 41a as described in the related art. In the gas meter as a whole, the microcomputer 49 of FIG.
The microcomputer 9 described in FIG. 7 used for the safety function
And can be used by modifying the conventional program of the microcomputer 9.

Embodiment 2 In Embodiment 1, the pulse width ratio Pn is adopted as a numerical value corresponding to the ratio Tn / ΔTn between the pulse width Tn and ΔTn. A correspondence table between n and the pulse width ratio Pn is created as shown in Table 2 and stored in the memory of the microcomputer 49 as the table 53. In the second embodiment, instead of the pulse width ratio Pn, Pn ′ = Tn / By adopting ΣTn = Pn / 20, the unknown flow rate Q is calculated by Q = k · Pn ′ / T.

In this case, the following Table 3 is created instead of Table 2 and stored in the memory of the microcomputer 49 as a table.

[0036]

[Table 3]

[Embodiment 3] Since the flow rate is inversely proportional to the pulse width (period) of the flow rate pulse, the flow rate exceeds a predetermined value in order to judge the limit such as the flow rate over using a gas meter with a safety function. Instead of checking whether or not the pulse width (period) of the flow rate pulse has become smaller than a predetermined value, it may be monitored. In this case, the pulse width also changes even if the flow rate is constant during one revolution of the crankshaft. Therefore, the pulse widths (periods) T ₁ , T ₂ ,.
n, ..., by creating the table 2 from the T _20, and the pulse width T that is stored in the memory, measured by the measurement mode as a table 53 in the case and similarly FIG. 4 of the first embodiment, pulse N at that time
o. , A true pulse width T ′ corresponding to the unknown flow rate Q is calculated as T ′ = T / Pn.

[Fourth Embodiment] The fourth embodiment differs from the first embodiment only in the configuration of the rotation detecting means. That is, as shown in FIG. 6, a speed-increasing second wheel 45b meshed with a speed-increasing first wheel 45a fitted and fixed to a lower extension of the crankshaft 39, and a pinion 45c serving as a speed-increasing third wheel in mesh with this. Speed increasing gear train 45A and pinion 45c
The rotary magnet 46A provided on the axis of the shaft and a reed switch 47A as a magnetic sensor disposed in proximity to the rotary magnet 46A constitute a rotation detecting means 48A. The gear ratio of the speed-up gear train 45A is 10, and the reed switch 47A generates 20 flow pulses per rotation of the crankshaft 39. Since other structures are the same as those of the first embodiment, the same portions are denoted by the same reference numerals and description thereof will be omitted.

[0039]

Since the gas flow measuring method and gas meter of the present invention are constructed as described above, a plurality of flow pulses can be obtained per one rotation of the crankshaft, and each flow pulse corresponds to the flow rate Q or the flow rate. As a result, the gas flow rate can be accurately measured in a short time.

[Brief description of the drawings]

FIG. 1A is an exploded perspective view of a main part, and FIG. 1B is a perspective view of a weighing mechanism in an embodiment of the present invention.

FIG. 2 shows a waveform of a flow pulse and a pulse N according to an embodiment of the present invention.
o. FIG.

FIG. 3 is a diagram showing a change in a pulse width ratio according to the embodiment of the present invention.

4A is a block diagram of a main part of an embodiment of the present invention, FIG.
(B) is a timing chart.

FIG. 5 is a flowchart of an embodiment of the present invention.

FIG. 6 is an exploded perspective view of a main part of the embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating a configuration of a safety function unit according to the related art.

FIG. 8 is a front view of a conventional gas meter.

FIG. 9 is a plan view of a conventional gas meter.

FIG. 10 is a sectional view taken along the line AA in FIG. 8 of the prior art.

FIG. 11 is a perspective view of a conventional technique.

FIG. 12 is an exploded perspective view showing a part of the related art.

[Explanation of symbols]

 21A, 21B Rubber film 39 Crankshaft 48, 48A Rotation detecting means 50 Timer 51 Pulse No. Counter 52 Table creation means 53 Table (table) 54 Calculation means

Claims (4)

[Claims] 1. A film-type gas meter provided with rotation detecting means for generating a plurality of flow pulses per rotation of a crankshaft which rotates in conjunction with the reciprocating movement of a rubber film. A constant flow rate Q ₀ is supplied, and the pulse No.
n and its pulse No. 1. a table creation mode for creating a correspondence table of numerical values corresponding to the ratio Tn / ΔTn between the pulse width Tn of the flow rate pulse and ΔTn; The pulse width T and the pulse No. of the flow pulse when the unknown flow Q flows. 2. This pulse No. Of the pulse No. in the correspondence table. 3. Read the numerical value corresponding to the ratio Tn / ΣTn corresponding to from the correspondence table; A gas flow measurement method, comprising: a measurement mode for calculating an unknown flow rate Q from the numerical value and the pulse width T. 2. A film-type gas meter provided with rotation detecting means for generating a plurality of flow pulses per rotation of a crankshaft which rotates in conjunction with reciprocal movement of a rubber film. A constant flow rate Q ₀ is supplied, and the pulse No.
n and its pulse No. 1. a table creation mode for creating a correspondence table of numerical values corresponding to the ratio Tn / ΔTn between the pulse width Tn of the flow rate pulse and ΔTn; The pulse width T and the pulse No. of the flow pulse when the unknown flow Q flows. 2. This pulse No. Of the pulse No. in the correspondence table. 3. Read the numerical value corresponding to the ratio Tn / ΣTn corresponding to from the correspondence table; A gas flow measuring method, comprising: a measurement mode for calculating a true pulse width T ′ corresponding to an unknown flow rate Q from the numerical value and the pulse width T. 3. A rotation detecting means for generating a plurality of flow pulses per one rotation of the crank shaft to rotate in conjunction with the reciprocating movement of the rubber film, when a current of a constant flow rate Q _0, the flow pulse pulse No. n to count the pulse No. A counter,
A timer for measuring the pulse width Tn of each flow pulse; n and the ratio Tn / ΔT of the pulse width Tn to ΔTn
n, a storage unit for storing a correspondence table, and a pulse No. when an unknown flow rate Q flows. And pulse width T
Of each of the pulse Nos. Measured with a counter and a timer and found. A gas meter comprising a calculating means for reading a numerical value corresponding to a ratio Tn / ΣTn corresponding to the following from a correspondence table of the storing means and calculating an unknown flow rate Q from the numerical value and the pulse width T. 4. A rotation detecting means for generating a plurality of flow pulses per rotation of a crankshaft which rotates in conjunction with a reciprocating movement of a rubber film, and a pulse N of a flow pulse when a constant flow Q ₀ is supplied.
o. n to count the pulse No. A counter, a timer for measuring the pulse width Tn of each flow pulse, and a pulse No. n, and the ratio of the pulse width Tn to ΔTn, Tn /
表 Table creation means for creating a correspondence table with numerical values corresponding to Tn, storage means for storing the correspondence table, and pulse No. when an unknown flow rate Q flows. And pulse width T
Of each of the pulse Nos. Measured with a counter and a timer and found. And a calculating means for reading a numerical value corresponding to the ratio Tn / ΣTn corresponding to the above from the correspondence table of the storage means and calculating a true pulse width T ′ corresponding to the unknown flow rate Q from the numerical value and the pulse width T. A gas meter, comprising: