JP2002090188A - Gas measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas measuring device for measuring by converting a gas flow rate from a mass flow rate into a volume flow rate. SOLUTION: This gas measuring device has a gas measuring means A and a conversion means B for converting the quantity of consumed gas determined by the gas measuring means. The gas measuring means A is a mass flow type gas measuring means A1 for measuring the mass flow rate of gas flow flowing in a gas supply route, determining a gas flow value based on the measured mass flow rate, and measuring the quantity of consumed gas by integrating the determined gas flow value. The conversion means B includes a conversion part 15a11 for converting the mass flow determined by the mass flow type gas measuring means A1 into the volume flow rate and a correction part 15a12 for correcting the volume flow rate converted by the conversion part 15a11 corresponding to surrounding circumstances (outside air temperature information from a temperature detection means 18 and outside air pressure information from an absolute pressure detection means 18).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas metering device for measuring gas consumption, and more particularly to a gas metering device for converting a gas flow rate from a mass flow rate to a volume flow rate for measurement.

[0002]

2. Description of the Related Art This type of gas metering device is generally called a microcomputer gas meter. In addition to its main function of measuring gas usage, various functions used in gas supply include functions important for security. In addition, a function for convenience of consumers and a function for rationalization of LP gas distributors are incorporated.

On the other hand, as a microcomputer gas meter, a so-called membrane gas meter is generally used.
This membrane gas meter has a membrane metering section that measures gas flowing into the gas inlet and flowing out of the gas outlet, and the switching valve is switched every time a constant flow rate flows to alternately into the room partitioned by the diaphragm. The diaphragm is reciprocated by flowing gas and discharging gas in a room already filled with gas, and the metering display section comprising a counter is driven in conjunction with the reciprocation of the diaphragm to accumulate gas usage. And display it.

[0004]

However, in this membrane gas meter, the amount of gas used is measured by measuring the "volume" flow rate of the gas by the above-described configuration, and the "volume" is determined by the surrounding volume. It could not be said that the gas usage was accurately measured because it changes with temperature and pressure.

That is, in a membrane gas meter using a security block having a total flow rate cutoff function, the temperature changes according to the season, and therefore the volume of gas changes. It cannot always be said that security is at the same level. Further, since there is a temperature difference between different regions, for example, between Hokkaido and Okinawa, it cannot be said that even membrane gas meters having the same structure installed in different regions have the same level of security. Similarly, there is a pressure difference between high and low altitude areas, so it cannot be said that security is at the same level.

[0006] Further, regarding security, if there are many erroneous shut-offs despite the safe use, the general user must open the valve one by one, which is troublesome. On the other hand, even if it is in a really dangerous state, if it is not cut off or if the cut off is delayed, it may lead to an accident such as explosion or poisoning, which is dangerous.

For example, when the temperature is high, the gas expands,
Due to the reduced density, even if the same volume leaks, the room may not reach the explosive limit concentration. Conversely, if the temperature is low, the gas is compressed and the density becomes high, so even if the same volume is leaked, the room may exceed the explosive limit concentration, which is dangerous.

As described above, in order to perform security logic with high accuracy, there is a limit in a microcomputer gas meter based on "volume flow rate" such as a membrane gas meter.

On the other hand, in recent electronic gas meters,
Some gas flow rates can be measured by "mass" instead of "volume". A sensor that can measure “mass” includes, for example, a flow sensor. The flow rate of the gas measured using the flow sensor is not a “volume” flow rate but a “mass” flow rate. As will be understood from the measurement principle of the flow sensor described later, the way of transmitting heat depends on the density of gas.
If you use a flow sensor, instead of measuring based on “volume”, you can measure “mass” with high accuracy and high reliability.
Security can be enforced. That is, since the current gas flow rate does not fluctuate depending on the use environment (temperature, pressure, etc.) and can be measured with a substantial mass, it is accurate for security.

However, in the current gas industry, there is no problem in performing security at a mass flow rate, but performing gas consumption at a mass flow rate is still the basis (infrastructure).
Is not maintained. Ideally, security is based on "mass" flow and gas usage is based on "volume".

[0011] As an example, a major gas company sets a gas usage fee according to a region. For example, in Hokkaido, where the temperature is low, the same volume will use more gas than in regions with high temperatures, so the gas usage fee per unit volume will be set slightly higher than in other regions. are doing.

In the transition period from a volume flow meter to a mass flow meter, it is difficult to manage two types of fees depending on the type of meter (for example, a membrane gas meter and a flow sensor gas meter).

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas metering device that measures a gas flow rate by converting the gas flow rate from a mass flow rate to a volume flow rate.

[0014]

In view of the above-mentioned object,
The gas metering device according to the first aspect of the present invention measures a gas flow rate flowing through a gas supply path and integrates the measured gas flow rates as shown in the basic configuration diagram of FIG. Gas measuring means A for measuring the gas flow rate, and a conversion means B for converting the amount of gas used obtained by the gas measuring means, wherein the gas measuring means A is provided for measuring a gas flow flowing through a gas supply path. A mass flow type gas measuring means A1 for measuring a mass flow rate, obtaining a gas flow value based on the measured mass flow rate, integrating the obtained gas flow value and measuring a gas usage amount, wherein the conversion means B is A conversion unit 15a11 for converting the mass flow rate obtained by the mass flow type gas metering means A1 into a volume flow rate, and a correction unit 1 for correcting the volume flow rate converted by the conversion unit 15a11 according to the surrounding environment.
5a12.

According to the first aspect of the present invention, the gas metering device measures the flow rate of the gas flowing through the gas supply path, and integrates the measured gas flow to measure the gas usage of the combustion appliance. Means A and conversion means B for converting the gas usage determined by the gas metering means are provided. The gas measuring means A measures a mass flow rate of a gas flow flowing through the gas supply path, and obtains a gas flow rate value based on the measured mass flow rate,
This is a mass flow type gas measuring means A1 for integrating the obtained gas flow values and measuring the gas usage. The conversion unit B includes a conversion unit 15a11 that converts the mass flow rate obtained by the mass flow type gas metering unit A1 into a volume flow rate, and a conversion unit 15a11.
And a correction unit 15a12 for correcting the volume flow rate converted in accordance with the surrounding environment.

According to a second aspect of the present invention, there is provided the gas metering device of the first aspect, further comprising temperature detecting means 15n for detecting an outside air temperature in the surrounding environment.

According to the second aspect of the present invention, the gas metering device further includes temperature detecting means 15n for detecting an outside air temperature in the surrounding environment.

According to a third aspect of the present invention, in the gas metering apparatus according to the second aspect of the present invention, an absolute pressure detecting means 15o for detecting an external pressure in the surrounding environment is further provided.

According to the third aspect of the present invention, the gas metering device further includes an absolute pressure detecting means 15o for detecting an external atmospheric pressure in the surrounding environment.

According to a fourth aspect of the present invention, in the gas measuring device according to any one of the first to third aspects, the mass flow type gas measuring means includes a flow sensor. .

According to the fourth aspect of the present invention, the mass flow type gas metering means includes a flow sensor.

According to a fifth aspect of the present invention, in the gas metering apparatus of the fourth aspect, the flow sensor includes a heater for heating the gas flowing through the gas supply path;
An upstream temperature sensor that is disposed upstream of the gas with respect to the heater and detects a temperature of the gas and outputs a first temperature detection signal; and an upstream temperature sensor that is disposed downstream of the gas with respect to the heater,
It is characterized by comprising a downstream temperature sensor for detecting a gas temperature and outputting a second temperature detection signal, and a support substrate for supporting the heater, the upstream temperature sensor and the downstream temperature sensor.

According to the fifth aspect of the present invention, the flow sensor includes a heater for heating the gas flowing through the gas supply path;
An upstream temperature sensor that is disposed upstream of the gas with respect to the heater and detects the temperature of the gas and outputs a first temperature detection signal, and is disposed downstream of the gas with respect to the heater and detects the temperature of the gas A second temperature detection signal, and a support substrate that supports the heater, the upstream temperature sensor, and the downstream temperature sensor.

According to a sixth aspect of the present invention, in the gas metering device of the fourth aspect, the flow sensor includes a heater for heating the gas flowing through the gas supply path;
An upstream temperature sensor that is disposed upstream of the gas with respect to the heater and detects a temperature of the gas and outputs a first temperature detection signal; and an upstream temperature sensor that is disposed downstream of the gas with respect to the heater,
A downstream temperature sensor that detects the temperature of the gas and outputs a second temperature detection signal; and a third temperature detection signal that is disposed in a direction substantially perpendicular to the gas flow direction with respect to the heater and detects the gas temperature. And a support substrate that supports the heater, the upstream temperature sensor, the downstream temperature sensor, and the horizontal temperature sensor.

According to the invention described in claim 6, the flow sensor includes a heater for heating the gas flowing through the gas supply path,
An upstream temperature sensor that is disposed upstream of the gas with respect to the heater and detects the temperature of the gas and outputs a first temperature detection signal, and is disposed downstream of the gas with respect to the heater and detects the temperature of the gas A downstream temperature sensor that outputs a second temperature detection signal, and a lateral temperature sensor that is disposed in a direction substantially perpendicular to the gas flow direction with respect to the heater, detects the temperature of the gas, and outputs a third temperature detection signal. Sensor, heater, upstream temperature sensor,
A support substrate that supports the downstream temperature sensor and the lateral temperature sensor.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In summary, the present invention uses a mass flow rate gas measuring means for measuring a gas flow rate as a mass flow rate as a gas measuring means, and uses a mass flow rate gas measuring means which measures the gas flow rate as a mass flow rate. This is converted into a volume flow rate by a conversion means and displayed. Here, the mass flow rate corresponds to the mass of the gas flowing through the gas passage per unit time, and the unit thereof is kilogram / hour (Kg / h). The volume flow rate means that the gas flows through the gas passage per unit time. It corresponds to the volume of gas, and its unit is liter / hour (L / h).

According to Boyle-Charles' law, (PV)
/ T = constant value. Where P: pressure, V: volume,
T: temperature. For example, LP gas is a mixed gas of propane and butane, and 1 kg (Kg) = 500 liters (L) under a use environment condition of an external temperature of 0 ° C. and 1 atm. Therefore, the mass flow rate of the gas, for example, the LP gas measured by the mass flow rate gas measuring means can be easily converted to the volume flow rate at 0 ° C. and 1 atm by multiplying the conversion rate by 500. When the use environment condition becomes the outside temperature 0 ° C. and the outside air pressure which are different from 1 atm, the correction according to the temperature and the pressure is performed at the time of conversion, so that the mass can be obtained under any use environment condition. The flow rate can be converted to a volume flow rate.

An embodiment of a gas metering device according to the present invention will be described below with reference to the drawings. An electronic gas meter, which is a gas metering device according to the present embodiment, is configured to be applied to an LP gas supply facility as shown in FIG. In FIG. 2, an electronic gas meter 1 controls a high-pressure LP gas stored in an LP gas container 2 by a pressure regulator 3.
The pressure is adjusted to the supply pressure by the gas bath kettle 4 and the stove 5
It is installed in a pipe 6 in a gas supply path for supplying gas to a combustion appliance, and measures the amount of gas consumed in the combustion appliance. The piping to the gas stove 5 etc.
A closing valve 7 is provided.

The electronic gas meter 1 is, as shown in FIG.
A shutoff valve 11 provided in a gas passage (not shown) connected to a pipe of a gas supply passage (not shown) for shutting off gas supply by closing the valve, a seismic sensor 12 for sensing a seismic intensity equal to or higher than a predetermined value, , A flow sensor 14 for obtaining a signal that changes according to the flow velocity of the gas flow flowing through the gas path, a temperature sensor 17 for detecting the outside air temperature as temperature detecting means, and an absolute pressure detecting means as An absolute pressure gauge 18 for detecting the outside air pressure and a controller 15 as a control unit are built in.

The controller 15 has a microcomputer (μCO) operating according to a predetermined program.
M) It has 15a. The microcomputer 15a
As is well known, a central processing unit (CPU) 15a that performs various processes and controls according to a predetermined program.
1. Built-in ROM 15a2, which is a read-only memory storing programs and the like for the CPU, and RAM 15a3, which is a readable and writable memory that stores various data and has an area necessary for processing by the CPU. .

The controller 15 includes the shut-off valve 11,
Connector 15 to which seismic sensor 12, pressure sensor 13, flow sensor 14, temperature sensor 17, and absolute pressure gauge 18 are connected
b and a drive signal for opening and closing the shut-off valve 11 in accordance with the open / close signal output from the μCOM 15a.
Valve driving circuit 15c that outputs the signal through
5b input from the seismic sensor 12, the pressure sensor 13, the temperature sensor 17, and the absolute pressure gauge 18
Interface circuit 15d for input to M15a
And the flow sensor 14 via the interface circuit 15d and the connector 15b, respectively.
And a sensor circuit 15e that amplifies the detection output of the flow sensor 14.

The controller 15 further has a terminal block 15f to which various external devices outside the electronic gas meter 1 are connected, and transmits and receives signals between the μCOM 15a and the external device via the terminal block 15f. Interface circuit 15g. Specifically, the controller 1
5, via a terminal block 15 f, for example, an in-home display panel 21 provided in the house for performing various displays related to the gas meter, a home operation device 22 for performing various remote operations on the gas meter, and in the house A gas alarm 23 that detects a gas above an alarm level and issues an alarm, a function similar to that of the gas alarm 23, and a CO second gas alarm / CO alarm that detects a CO gas above the alarm level and issues an alarm 24, an automatic switching regulator 25 for automatically outputting a signal corresponding to the switching operation of the automatic switching type pressure regulator for automatically switching a plurality of LP gas containers, a management center of a gas distributor via a public line such as a telephone line. A network control unit (NCU) 26 for controlling communication with the network is connected.

The controller 15 further comprises a μCO
A liquid crystal display (LCD) 15h connected to the M15a for displaying various information such as an integrated value of gas consumption and an alarm; a lithium battery 15i for supplying operating power to each unit in the controller 15; 1
A container replacement switch 15j, which is connected to the μCOM 15a via the 5d and is operated when replacing the LP gas container, a shutoff valve open switch 15k which is turned on when the closed shutoff valve 11 is opened, and a battery 15i. Voltage drop of μ
The COM 15a has a battery voltage detection circuit 15m for detecting the voltage for monitoring.

The CPU 15a1 of the μCOM 15a performs processing in accordance with a predetermined program, and
4 and a sensor circuit 15e, gas measuring means,
It constitutes a conversion unit including a conversion unit and a correction unit.

The CPU 15a1 of the μCOM 15a also
By performing the processing according to the specified program, the total flow rate cutoff, the increase flow rate cutoff, the use time cutoff, the leak cutoff during the return safety check, the gas leak alarm interlocking cutoff, the seismic sensor operation cutoff, the flow rate minute leak warning, the pressure type It functions as a functional means for performing a number of functions including security functions, such as a micro leak warning, an adjustment pressure abnormality warning, a blockage pressure abnormality warning, a pressure drop cutoff, an ignition registration, a test cutoff, an automatic meter reading, and a remaining amount management.

First, gas measurement will be described. Specifically, the flow sensor 14 is a micro flow sensor that measures a gas flow rate as a mass flow rate.
As shown in (1), it is arranged on the inner wall of the gas passage 16 in the gas meter 1. The flow sensor 14 and the sensor circuit 15
e, the gas measuring means functions as a mass flow type gas measuring means, and the CPU 15a1 determines the flow rate of the LP gas flowing through the gas path 16 based on the detection output from the flow sensor 14 and the sensor circuit 15e as the mass flow rate Qm (Kg / h). ).

Next, the CPU 15a1 functions as a conversion unit, and converts the calculated LP gas mass flow rate Qm (Kg / h)
Multiplying by the gas conversion rate 500, the volume flow rate of LP gas Ql
(L / h).

Next, the CPU 15a1 functions as a correction unit, and reads the outside air temperature information from the temperature sensor 17 and the absolute pressure gauge 18
Is converted based on the outside air pressure information from
/ H). The value of the corrected volume flow rate Ql (L / h) is displayed on the in-home display panel 1 as the gas usage.

On the other hand, the mass flow rate Qm (Kg / h) of the LP gas obtained as described above is used in a security function such as a total flow rate cutoff and a flow rate type minute leak warning.

As described above, the gas metering is measured based on the mass flow rate, but is converted into the volume flow rate at the stage of displaying the gas usage amount, so that the volume display becomes familiar with a conventional membrane gas meter or the like. , Do not be mistaken. In addition, since the security function is performed using the measured mass flow rate, the security function is more accurate than when the volume flow rate is used.

Next, a detailed structure of the flow sensor (micro flow sensor) 14 and a flow rate measuring method using the flow sensor 14 will be described with reference to FIGS.

As shown in FIG. 4, the micro flow sensor 14 includes a micro heater 104 formed on a Si substrate 102, a downstream thermopile 105 formed downstream of the micro heater 104, and a micro heater 104.
Gas flow direction (X direction) on both sides of the upstream thermopile 108 formed on the upstream side of the
Right and left thermopiles 11 which are arranged in a direction substantially perpendicular to the axis and which detect a physical property value of gas and output a temperature detection signal.
1 and 113.

As described in detail below, the downstream thermopile 105 and the upstream thermopile 108
The right thermopile 111 and the left thermopile 113 help to detect the gas flow rate, and help to detect the gas type.

FIGS. 5 and 6 are a structural view and a sectional view of the micro flow sensor of FIG. In FIG. 5, a micro flow sensor 14 includes a Si substrate 102, a diaphragm 103, a micro heater 104 formed on the diaphragm 103 and made of platinum or the like, and a micro heater 104.
Power supply terminals 106A and 106 for supplying a drive current from a power supply (not shown) to a downstream thermopile 105 formed on the diaphragm 103 on the downstream side of the
B, diaphragm 10 upstream of micro heater 104
3, an upstream thermopile 108, first output terminals 109A and 109B for outputting a first temperature detection signal output from the upstream thermopile 108, and a second temperature detection signal output from the downstream thermopile 105. And second output terminals 107A and 107B. The downstream thermopile 105 and the upstream thermopile 108 constitute a temperature sensor.

The micro flow sensor 14 is disposed in a direction substantially perpendicular to the gas flow direction (the direction from arrow P to arrow Q in FIG. 5) with respect to the micro heater 104, and detects the physical property value of the gas. Right thermopile 111 that outputs right temperature detection signal (corresponding to third temperature detection signal)
And third output terminals 12A and 12B for outputting a right temperature detection signal output from the right thermopile 111;
A left thermopile 113 that is disposed in a direction substantially perpendicular to the gas flow direction with respect to the microheater 104 and detects a physical property value of the gas and outputs a left temperature detection signal (corresponding to a third temperature detection signal); Fourth output terminal 14 for outputting left-side temperature detection signal output from 113
A, 14B and resistors 15, 16 for obtaining gas temperature
And output terminals 17A and 17B for outputting gas temperature signals from the resistors 15 and 16. The right thermopile 111 and the left thermopile 113 constitute a temperature sensor.

The upstream thermopile 108, the downstream thermopile 105, the right thermopile 111 and the left thermopile 113 are composed of thermocouples. This thermocouple is made of p ++-Si and Al, has a cold junction and a hot junction, detects heat, and generates a thermoelectromotive force from a temperature difference between the cold junction and the hot junction, A temperature detection signal is output.

Further, as shown in FIG.
, A diaphragm 103 is formed, and the diaphragm 103 is formed with respective hot junctions of a microheater 104, an upstream thermopile 108, a downstream thermopile 105, a right thermopile 111, and a left thermopile 113.

According to the micro flow sensor 14 configured as described above, when the micro heater 104 starts heating with an external drive current, the micro heater 10
The heat generated from 4 is transferred to the respective hot junctions of the downstream thermopile 105 and the upstream thermopile 108 using gas as a medium. Since the cold junction of each thermopile is on the Si substrate (Si substrate) 102, the temperature is at the substrate temperature.
05, it is heated by the transferred heat,
The temperature rises above the substrate temperature. Each thermopile generates a thermoelectromotive force based on the temperature difference between the hot junction and the cold junction, and outputs a temperature detection signal.

The heat transmitted by using the gas as a medium is transmitted to each thermopile by a synergistic effect of a thermal diffusion effect of the gas and a flow velocity of the gas flowing from P to Q. That is, when there is no flow velocity, the heat is uniformly transmitted to the upstream thermopile 108 and the downstream thermopile 105 by thermal diffusion, and the first thermopile 108 from the upstream thermopile 108
The difference signal between the temperature detection signal and the second temperature detection signal from the downstream thermopile 105 becomes zero.

On the other hand, when the flow velocity is generated in the gas, the amount of heat transmitted to the hot junction of the upstream thermopile 108 increases due to the flow velocity, and the difference signal between the second temperature detection signal and the first temperature detection signal is reduced to the flow velocity. It will be a corresponding positive value.

On the other hand, when the microheater 104 starts heating with an external drive current, the microheater 10
The heat generated from 4 is transmitted to the right thermopile 111 arranged in the direction substantially perpendicular to the gas flow direction with respect to the micro heater 104 only by the heat diffusion effect of the gas without being affected by the gas flow velocity. Micro heater 1
Similar heat is transmitted to the left thermopile 113 disposed substantially perpendicular to the gas flow direction with respect to the thermopile 04.
For this reason, the third thermopile 111 generates
Based on the right temperature detection signals output from the output terminals 112A and 112B and / or the left temperature detection signals output from the fourth output terminals 114A and 114B by the electromotive force of the left thermopile 113, heat conduction, heat diffusion, specific heat, etc. It is possible to calculate a physical property value of the gas such as a thermal diffusion constant determined by the above.

Further, according to the micro flow sensor 14, the micro heater 104,
Upstream thermopile 108, Downstream thermopile 10
5. Right thermopile 111 and left thermopile 1
Since the 13 is formed, these heat capacities can be reduced and power consumption can be reduced. Further, since the configuration of the micro flow sensor 14 is simple, there is an effect that the micro flow sensor 14 can be manufactured at low cost.

Next, the aforementioned micro flow sensor 14
Even if the type or composition of the gas changes,
Regardless of this, a gas metering means that can always measure the gas flow rate with high accuracy will be described.

FIG. 7 is a block diagram showing the construction of a gas metering means using the micro flow sensor 14 shown in FIGS. In FIG. 5, the sensor circuit 15e is a differential amplifier 3
3 and amplifiers 35a and 35b. Differential amplifier 33
Amplifies the difference signal between the second temperature detection signal from the downstream thermopile 105 in the microflow sensor 14 and the first temperature detection signal from the upstream thermopile 108 in the microflow sensor 14, and the amplifier 35a The right temperature detection signal from the right thermopile 111 in the microflow sensor 14 is amplified, and the amplifier 35b amplifies the left temperature detection signal from the left thermopile 113 in the microflow sensor 14.

The CPU 15a1 of the μCOM 15a includes an adder 15a1-1 for adding the right temperature detection signal from the amplifier 35a and the left temperature detection signal from the amplifier 35b,
A division 15a1-2 for dividing a difference signal between the second temperature detection signal and the first temperature detection signal obtained by the differential amplifier 33 by an addition signal output from the addition section 15a1-1;
A flow rate calculator 15a1-3 that calculates the gas flow rate based on the division signal output by a1-2, and physical properties such as heat conductivity, specific heat, viscosity, and density of the gas based on the addition signal output by the addition section 15a1-1. Fluid property value calculation unit 15a for calculating the value
1-4.

Next, a flow rate measuring method realized by the gas measuring means of FIG. 7 will be described with reference to a flowchart shown in FIG.

First, when the microheater 104 is heated by a driving current based on a pulse signal from the outside (step S11), a second temperature detection signal is output from the downstream thermopile 105, and a first temperature detection signal is output from the upstream thermopile 108. It is output (step S13). The second temperature detection signal is output to the differential amplifier 33, and the first temperature detection signal is output to the differential amplifier 33. FIG. 9 shows a response of the first temperature detection signal and the second temperature detection signal to the pulse signal.

Next, the differential amplifier 33 amplifies a difference signal between the second temperature detection signal from the downstream thermopile 105 and the first temperature detection signal from the upstream thermopile 108 (step S15).

The adder 15a1-1 is connected to the amplifier 3
5a and the left-side temperature detection signal from the amplifier 35b are added to obtain an addition signal (step S).
17). FIG. 10 shows a timing chart of the right temperature detection signal, the left temperature detection signal, and the addition signal. next,
The division 15a1-2 divides the amplified difference signal obtained in step S15 by the addition signal obtained in step S17 to obtain a division signal (step S19).

Subsequently, the flow rate calculator 15a1-3 calculates an accurate gas flow rate based on the division signal obtained in step S19 (step S21). Further, based on the addition signal obtained in step S17 and the accurate flow rate of the gas calculated in step S21, the fluid property value calculator 15a1-4 calculates the physical properties of the gas such as the thermal conductivity, specific heat, viscosity, and density of the gas. A value is calculated (step S23).

As described above, the right thermopile 111 and the left thermopile 113 arranged in the direction orthogonal to the gas flow direction detect the physical properties of the gas to measure the thermal conductivity of the gas. Become. When the flow velocity of the gas is zero, the speed at which heat is transmitted by the gas depends on the thermal conductivity and the thermal diffusion constant (one of the physical properties of the gas) determined by thermal diffusion, specific heat, and the like. When the flow velocity is zero, a thermal diffusion constant is obtained from a temperature difference between the right thermopile 111, the left thermopile 113, and the microheater 104. The larger the temperature difference, the smaller the thermal diffusion constant.

The magnitude of the thermal diffusion constant also affects the first temperature detection signal output by the upstream thermopile 108 and the second temperature detection signal output by the downstream thermopile 105,
These values change according to the magnitude of the thermal diffusion constant. Therefore, in principle, by dividing the first temperature detection signal and the second temperature detection signal or the difference between them by the thermal diffusion constant, even if the gases have different thermal diffusion constants, Even if the type of gas is used, an accurate flow rate can be calculated.

On the other hand, when the flow rate is not zero, heat is carried downstream by the gas flow, and the amount of heat reaching the right thermopile 111 and the left thermopile 113 decreases accordingly. That is, the right thermopile 1
11 and the heat diffusion around the left thermopile 113
Increased by gas flow. Here, it is generally known that the rate of increase of the thermal diffusion is proportional to the square root of the flow velocity of the gas, and in principle, the thermal diffusion constant of the gas is such that even if the flow rate of the gas is known in some way, In this case, it can be estimated at any flow rate.

On the other hand, also around the upstream thermopile 108 and the downstream thermopile 105, the right thermopile 111 and the left thermopile 1
13, the increase in thermal diffusion (micro heater 10
4), and when the gas flow rate increases, the heat diffusion increases,
The difference between the temperature of the gas around the downstream thermopile 105 and the temperature of the gas around the upstream thermopile 108 becomes smaller.

For this reason, the downstream thermopile 10, which should normally increase in proportion to the increase in the gas flow velocity,
5 and the upstream thermopile 108
If the difference signal from the first temperature detection signal is smaller due to the increase in the thermal diffusion, and the flow rate of the gas becomes too large, the increase due to the increase in the flow velocity exceeds the decrease due to the increase in the heat diffusion. May increase, but the difference signal between the second temperature detection signal and the first temperature detection signal may decrease.

Therefore, when the flow rate is zero, the sum of the right temperature detection signal output by the right thermopile 111 and the left temperature detection signal output by the left thermopile 113 is considered to be “1”, and If there is, the ratio of the added value of the right temperature detection signal and the left temperature detection signal,
The operation is multiplied by a coefficient representing the rate of change of the moving amount of heat, and the coefficient is multiplied by a difference signal between the second temperature detection signal from the downstream thermopile 105 and the first temperature detection signal from the upstream thermopile 108. .

That is, by dividing the difference signal between the second temperature detection signal and the first temperature detection signal by the sum of the right temperature detection signal and the left temperature detection signal, the flow rate excluding the influence of the change in heat diffusion is eliminated. Calculation becomes possible, and an accurate and high-resolution flow rate can be obtained.

In the above-described embodiment, the second thermopile 105 from the downstream thermopile 105
The amplified difference signal between the temperature detection signal and the first temperature detection signal from the upstream thermopile 108 is added to the division 15a1-2 by adding the right temperature detection signal from the amplifier 35a and the left temperature detection signal from the amplifier 35b. Part 15a1-1
By dividing by the addition signal obtained by adding in the above, the flow rate calculation excluding the influence of the change in the heat diffusion can be performed.

In the embodiment described above, the division 15
The acquisition of the division signal in a1-2 is performed by the flow rate calculation unit 15a1.
-3 is performed prior to the calculation of the flow rate. However, in order to eliminate the influence of a change in thermal diffusion that appears in the amplified difference signal between the second temperature detection signal and the first temperature detection signal, This is because there is no need to grasp the physical properties of the gas as strictly accurate values such as thermal conductivity, specific heat, viscosity, and density.

That is, in the above-described embodiment, the thermal conductivity, specific heat, viscosity, and density of a gas that cannot be specified unless the state of thermal diffusion is understood with high accuracy are calculated as physical property values by the fluid property value calculation units 15a1-4. In order to do so, the exact flow rate of the gas excluding the influence of the change in thermal diffusion is calculated in advance by the flow rate calculation unit 15a1-3, and this is calculated by the fluid property value calculation unit 15a1-4. Is reflected in.

However, the fluid property value calculation unit 1
Depending on the type of the factor calculated in 5a1-4, the calculation of the physical property value by the fluid physical property value calculating unit 15a1-4 is performed in advance, and the calculation of the physical property value from the downstream thermopile 105 from the differential amplifier 33 is performed. (2) On the basis of the amplified difference signal between the temperature detection signal and the first temperature detection signal from the upstream thermopile 108, the accurate flow rate of the gas excluding the influence of the change in heat diffusion is calculated later. Is also good.

As described above, according to the above-described gas metering means, the right thermopile 111 and the left thermopile 113 are arranged in the direction substantially perpendicular to the gas flow direction with respect to the micro heater 104, and the right temperature detection signal and the left temperature detection signal are provided. Since it is configured to output a signal, it is possible to accurately calculate the physical property values of the gas such as the thermal diffusion constant based on the right temperature detection signal and the left temperature detection signal without being affected by the gas flow direction, Therefore, the type of gas can be specified.

The flow rate of the gas calculated by the flow rate calculating section 15a1-3 is corrected based on the calculated physical properties of the gas. Therefore, the gas type and composition can be changed without any special measures. Even if it changes, the flow rate can be accurately measured.

As described above, the embodiment of the present invention has been described. However, the present invention is not limited to this, and various modifications and applications are possible.

For example, in the above-described embodiment, the correction relating to the outside air pressure is performed by using the absolute pressure gauge 18.
Even if the external pressure is fixed at 1 atm and only the correction for the temperature change is performed, the conversion can be roughly performed.
May be omitted. When the electronic gas meter 1 is used at a considerably high altitude, the provision of the absolute pressure gauge 18 provides a more accurate configuration.

In the above-described embodiment, the temperature correction is performed using the temperature sensor 17. However, the temperature sensor 17 is omitted, and the right thermopile 111 and the left thermopile 113 of the flow sensor 14 are replaced with the temperature sensor 17. You may divert instead of.

As a sensor capable of measuring the mass used in the mass flow type gas measuring means, another sensor such as a hot wire sensor or a thermocouple sensor is used instead of the flow sensor in the above-described embodiment. Is also good.

Further, the flow sensor 14 in the above-described embodiment may have a structure in which the right thermopile 111 and the left thermopile 113 constituting the temperature sensor are deleted.

[0079]

According to the first aspect of the present invention, the gas flow rate is measured as a mass flow rate, and the gas usage amount is measured as a volume flow rate and can be accurately measured and displayed regardless of the use environment.

According to the second aspect of the present invention, it is possible to accurately measure and display the gas usage regardless of a change in the outside air temperature.

According to the third aspect of the present invention, it is possible to accurately measure and display the gas usage regardless of a change in the outside air pressure.

According to the fourth aspect of the present invention, the mass flow type gas measuring means can be realized by using a flow sensor.

According to the fifth aspect of the present invention, the mass flow rate of the gas can be accurately measured.

According to the sixth aspect of the present invention, the mass flow rate of the gas can be measured with high accuracy, and the flow rate can be measured with high accuracy even when the type or composition of the gas changes.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing gas supply equipment to which the gas metering device according to the present invention is applied.

FIG. 3 is a circuit diagram showing an embodiment of a gas metering device according to the present invention.

FIG. 4 is a schematic diagram illustrating a schematic configuration of a flow sensor constituting a gas metering unit in FIG. 3;

FIG. 5 is a configuration diagram of the flow sensor of FIG. 4;

FIG. 6 is a cross-sectional view of the micro flow sensor of FIG.

FIG. 7 is a block diagram showing a configuration of a gas metering unit using the micro flow sensor of FIG. 4;

FIG. 8 is a flowchart showing a flow rate measuring method realized by the gas measuring means of FIG. 7;

FIG. 9 is a diagram showing a first temperature detection signal and a second temperature detection signal.

FIG. 10 is a diagram showing a right temperature detection signal and a left temperature detection signal.

[Explanation of symbols]

 A gas measuring means A1 mass flow type gas measuring means B converting means 15a11 converting part 15a12 correcting part 17 temperature detecting means 18 absolute pressure detecting means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G01F 1/696 G01F 15/04 3/22 15/06 15/04 1/68 104A 15/06 104B 201Z F Term (reference) 2F030 CA10 CB01 CC13 CD15 CD17 CE02 CE04 CE09 CE22 CE25 CE27 CF05 CF11 2F031 AB01 AC01 AC03 AE07 AF04 AF10 2F035 EA02 EA05 EA08

Claims (6)

[Claims] 1. A gas measuring means for measuring a flow rate of a gas flow flowing through a gas supply path, and integrating the measured gas flow rates to measure a gas usage amount of a combustion appliance. A gas measuring device having a converting means for converting an amount, wherein the gas measuring means measures a mass flow rate of a gas flow flowing through a gas supply path, and obtains a gas flow rate value based on the measured mass flow rate. Mass flow rate gas measuring means for integrating the determined gas flow rate value and measuring the gas usage amount, wherein the conversion means converts the mass flow rate determined by the mass flow rate gas measurement means into a volume flow rate. And a correction unit that corrects the volume flow rate converted by the conversion unit according to the surrounding environment. 2. The apparatus according to claim 1, further comprising a temperature detecting means for detecting an outside air temperature in the surrounding environment.
A gas metering device as described. 3. The gas metering device according to claim 2, further comprising absolute pressure detecting means for detecting an outside air pressure in the surrounding environment. 4. The gas metering device according to claim 1, wherein said mass flow type gas metering means includes a flow sensor. 5. A flow sensor, comprising: a heater for heating a gas flowing through the gas supply path; and a flow sensor disposed upstream of the gas with respect to the heater, detecting a temperature of the gas and outputting a first temperature detection signal. An upstream temperature sensor that is disposed downstream of the gas with respect to the heater, and a downstream temperature sensor that detects the temperature of the gas and outputs a second temperature detection signal; and the heater, the upstream temperature sensor, and The gas metering device according to claim 4, further comprising a support substrate that supports the downstream-side temperature sensor. 6. A heater for heating a gas flowing through the gas supply path, wherein the flow sensor is disposed upstream of the gas with respect to the heater, and detects a temperature of the gas and outputs a first temperature detection signal. An upstream temperature sensor that is disposed downstream of the gas with respect to the heater, and a downstream temperature sensor that detects the temperature of the gas and outputs a second temperature detection signal; and a flow direction of the gas with respect to the heater. And a lateral temperature sensor that is disposed in a direction substantially orthogonal to and detects a gas temperature and outputs a third temperature detection signal; and the heater, the upstream temperature sensor, the downstream temperature sensor, and the lateral temperature sensor. A supporting substrate for supporting,
The gas metering device according to claim 4, comprising: