JPH11118569A - Gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a flow rate correctly corresponding to a flammable gas by using an operation rule corresponding to the air until a gas flow measurement function is inspected and using an operation rule corresponding to a gas flow when the gas flow of a different kind is measured. SOLUTION: A heat flow rate-detecting means 101 outputs an electric signal corresponding to a change of a thermal state based on a gas flow, a gas flow rate-operating means 102 operates a gas flow rate corresponding to the signal, and a gas flow rate-integrating means 103 integrates the gas flow rates. An operation rule-holding means 201 of the gas flow rate-operating means 102 holds a plurality of operation rules corresponding to a plurality of gas kinds including the air. The operation rule corresponding to the air as the gas kind is used until a gas flow measurement function is inspected before the gas meter is shipped from a factory. When a flow of a gas different from the air is to be measured, the operation rule corresponding to the gas kind is used. An operation rule-switching means switches the rules. For instance, LPG gas or the like flammable gas can be calculated by the operation rule correctly corresponding thereto in actual use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a gas meter,
In particular, the present invention relates to a gas meter using measuring means such as a thermal mass flow meter.

[0002]

2. Description of the Related Art In general, a flow rate measuring device of a thermal mass flow meter type uses a temperature difference between a temperature detected on the upstream side of a fluid such as gas and a temperature detected on the downstream side after applying heat to the fluid. Measuring the mass flow rate of the fluid based on
Conversely, there is a method of measuring a mass flow rate of a fluid by using a phenomenon in which a heating wire or the like is cooled (or heated) by a fluid such as the gas. In any case, such thermal mass flow meter type flow measuring devices are used in a wide range of fields of fluid flow measurement, from those measuring relatively small flows to those having relatively large flows applied to general industrial processes. It has been used over a wide range. The use of gas meters is also expected to be promising, and research and development for its utilization are being actively conducted. This is considered to be due to the excellent features of the thermal mass flow meter in particular in terms of the measurement principle.

That is, a thermal mass flow meter generally detects the flow rate of a fluid such as a gas as its mass flow rate or mass flow rate. Therefore, for example, when measuring the flow rate of an LPG with a gas meter, the final measurement of the flow rate of the LPG is performed. It is a great feature that the flow rate converted to the standard state required as required can be measured without being affected by the pressure.

Moreover, the thermal mass flow meter has a feature that it can measure over a wide flow rate range from a measurement in a small flow rate range to a measurement in a relatively large scale and a high flow rate range.
For example, accurate measurement performance is required over a wide flow rate range from a small flow rate range such as a pilot water heater to a high flow rate gas usage by a relatively large-scale gas appliance such as a bath kettle. The technology is also attracting attention as a suitable technology for household gas meters.

In general, when a conventional gas meter is completed and shipped on a production line, the gas meter is generally referred to as a so-called "shipping time" in order to confirm whether or not the gas meter functions normally without any measurement failure. Product test evaluations have been performed. For example, in the case of a so-called membrane gas meter that mechanically detects a gas flow rate, which is the most common gas meter in the past, at the time of product evaluation at the time of shipment, such as LPG that is flowed during actual use, Since the use of flammable gas is too dangerous and reckless and uneconomical, instead, conduct a product test evaluation at the time of shipment using air that has no danger and is available free of charge. ing.

That is, the gas meter before the test evaluation, which has just been completed and does not know whether it functions normally as a gas meter or does not know whether there is a danger such as gas leakage or the like, is handled at the time of actual use. Real flammable L
Conducting PG and the like has extremely serious problems, such as a high risk of explosion due to gas leakage and the like, and a high risk of gas poisoning of the inspector.

Alternatively, it is conceivable to produce and use a non-flammable dummy gas having characteristics very close to physicochemical characteristics such as density and heat capacity of a real LPG handled in actual use. It is technically difficult to produce such non-flammable gas that has very similar physicochemical properties to LPG,
In addition, there is another problem in that the production and use of such a special noncombustible dummy gas causes another major inconvenience in that the material cost increases. In particular, in terms of manufacturing costs, it is strictly required to cut down the costs for incidental processes such as shipping inspection as much as possible, and shipping inspection methods that further increase such expensive costs are required. It has to be said that adoption is extremely inconvenient.

[0008] Therefore, at the time of product evaluation at the time of shipment, air that can be used safely and that is inexpensive (at least in terms of material costs) has been preferably used. This applies not only to conventional membrane gas meters, but also to so-called guess type gas meters, such as other ultrasonic systems and the above-mentioned thermal mass flow system, and is generally used in gas meters. In the product test evaluation at the time of shipment, product test evaluation was performed using air instead of flammable gas such as LPG in actual use.

[0009]

However, in the case of a gas meter using a thermal mass flow meter as described above, the value measured by the temperature sensor used in such a gas meter, such as the LPG, is particularly important. It was found that the measured value when measuring the flammable gas actually used and the measured value when measuring the air used at the time of the test evaluation were greatly different.

That is, as a characteristic of temperature detection in a temperature sensor used in a thermal mass flow meter, more specifically, in general, the output of a temperature sensor increases or decreases substantially linearly in accordance with the heat flow rate. Further, between the flow of LPG and the flow of air at the same flow velocity, the output from the temperature sensor always shows a larger value in the case of LPG than in the case of air.
In other words, in gas meters of the thermal mass flow meter type,
The heat flow rate of the fluid to be measured is calculated in accordance with the output of the temperature sensor, and the flow rate of the fluid is further calculated based on the heat flow rate. The flow rate value measured by flowing air through the gas meter is significantly different from the flow rate value measured by flowing LPG in actual use, and is always lower than that of LPG.

As described above, in the conventional gas meter of the thermal mass flow meter system in particular, there is a problem that the measured value at the time of product test evaluation and the measured value at the time of actual use are significantly different. In addition, a function used in calculating the flow rate from the output of the temperature sensor or a constant used in the calculation is used for the LPG in actual use and the air in shipping (inspection evaluation). Although it is conceivable, if this switching can be easily operated manually from the outside of the gas meter, the gas meter is generally installed outdoors so that anyone can touch it. When input, the flow rate calculation corresponding to the LPG actually used is switched to the flow rate calculation corresponding to the air, and there is a problem that a flow rate value significantly different from a normal LPG usage amount is calculated. .

Alternatively, for example, it is conceivable that a person involved in the work inputs the above-mentioned switching operation at the time of installation work or the like, but in any case, the inside of the gas meter is not visible from the outside after the factory shipment. Simply relying on the switching of arithmetic rules in software used in circuit systems depending on manual input operations often results in so-called human factor errors, such as forgetting the switching operation or input errors. There was also a problem that lacked.

The present invention has been made to solve such a problem. According to the present invention, air can be used instead of flammable gas such as LPG in actual use during product test evaluation at the time of shipment, and flammable gas such as LPG is always used in actual use. It is an object of the present invention to provide a thermal mass flow meter type gas meter capable of accurately measuring a flow rate of a reactive gas.

[0014]

First, a gas meter according to the present invention comprises a heat flow detecting means for outputting an electric signal in response to a change in a thermal state caused by a gas flow; In a gas meter having gas flow rate calculating means for calculating the flow rate of the gas flow in response to the output electric signal, and gas flow rate integrating means for integrating the flow rate of the gas flow, the gas flow rate calculating means includes at least air Is a gas flow rate calculation means holding a plurality of calculation rules respectively corresponding to a plurality of different gas types, including at least until the inspection of a function of measuring the gas flow before factory shipment as the gas meter. An arithmetic rule corresponding to air is used as the gas type, and when measuring a gas flow of a gas type different from the air, an arithmetic rule corresponding to the gas type is used. Wherein such gas flow rate calculation means performs the calculation, is characterized by comprising a calculating rule switching means for switching the operation rule in the calculation rule corresponding to the gas type.

That is, a gas meter is generally manufactured at a factory and completed as a gas meter, and then inspected at the time of shipment to determine whether it operates correctly as a meter. In this case, air is used instead of gas such as LPG. The gas flow rate calculation means can calculate the gas flow rate by using the calculation rule corresponding to the air since the inspection is performed instead.

When the malfunction and the proper function as a measuring instrument are confirmed, the gas meter is shipped as an official product. In this way, the gas meter is installed at the place of use and is actually used. From this time, a real combustible gas such as LPG flows through the gas meter. Therefore, at this time, that is, at the time of installation, the calculation rule switching means switches to the calculation rule corresponding to the gas type in actual use, and causes the gas flow rate calculation means to calculate the gas flow rate.

[0017] Thus, in the case of product test evaluation at the time of shipment, air can be used instead of flammable gas such as LPG at the time of actual use.
It becomes possible to measure the flow rate accurately corresponding to a combustible gas such as PG. However, switching of the operation rule as described above is
It is preferable that the switching operation itself be automated or an operation such as inputting an instruction for switching the operation rule be performed before the gas meter is actually used. Alternatively, it is more desirable that such an operation rule switching operation is not performed alone, but is performed together with an operation that must be performed between factory shipment and installation.

Therefore, secondly, in the gas meter according to the first aspect of the present invention, when a command to stop the operation is input from the outside, the operation is stopped by at least the heat flow rate detecting means and the gas flow rate calculating means. And when the command to start the operation is input from the outside, the operation is started at least for the heat flow rate detecting means, the gas flow rate calculating means, and the gas flow rate integrating means. The operation rule switching unit further includes: an operation rule switching unit that, when the operation stop command or the operation start command is input, changes the operation rule used in the gas flow rate calculation unit to the air. A calculation rule switching means for switching from the calculated calculation rule to a calculation rule corresponding to one of gas types different from the air. That.

Thirdly, in the gas meter according to the first or second aspect of the present invention, the gas meter is supplied with a gas different from the air (conducted).
When the gas flow rate calculation means uses a calculation rule corresponding to the air when the flow rate is calculated, the flow rate value calculated according to the calculation rule is compared with a predetermined threshold value, and the flow rate value is If it is determined that the value is larger than the threshold value, the calculation rule used in the gas flow rate calculation means corresponds to one of gas types different from the air from the calculation rule corresponding to the air. The gas meter further includes a gas calculation rule abnormality determination unit that switches to the calculated calculation rule by the calculation rule switching unit.

That is, the electric signal detected by the heat flow rate detecting means used in the gas meter generally differs greatly between the fuel gas such as LPG when the gas meter is actually used and the air during the shipping inspection. Characteristic. The difference is the same (true) between the electrical signals detected by the temperature sensor, for example, between LPG and air.
With respect to the flow rate, the output of LPG will be three times that of air. As described above, since the measurement results are significantly different, it is necessary to switch the operation rule as described above according to the present invention. If the calculation rule corresponding to the air is used in spite of the actual use, rather than utilizing the remarkably significant difference from
It can be determined automatically by the described technique. In other words, for the heat flow rate detecting means, even if the flow rate is the same, for example, in the case of the flow of the LPG gas, the flow rate is measured as about three times the flow rate of the air. In other words, L
Using air as a substitute for PG gas, to perform a flow measurement test that is almost equivalent to that in actual use, the measured value calculated from the electric signal detected by the heat flow detecting means should be approximately three times the measured value. As described above, it is necessary to calculate the LPG flow rate without changing the calculation rule corresponding to air. As a result, the calculation rule for normal gas is used. That is, a flow rate value that is three times as large as a normal operation value in the case where the flow rate has occurred is calculated.
Therefore, the flow rate of the gas actually used, such as LPG, is calculated using the operation rule corresponding to air without switching the operation rule (or coefficient) corresponding to air due to some operation error or disturbance. In the case of calculation, even if the gas flow rate at that time is small, it is not air but LP
Just because it is a gas like G, a flow rate value, that is, an abnormal value that cannot be considered in a normal state should be calculated immediately. Therefore, when such an abnormal value is calculated, it is determined as abnormal by the gas calculation rule abnormality determination means, and automatically switched to the calculation rule (or coefficient) corresponding to the original gas. be able to.

However, at this time, although a large number of gas leaks occur due to, for example, damage to the gas pipe on the downstream side, despite the fact that the calculation rules are for gas, the above-mentioned rules are used. Another abnormal situation in which an abnormal value is calculated can be considered, but even in such a case, there is no problem if the gas meter is equipped with a conventional gas leak alarm. Because even if such a gas leak occurs,
In this case, the gas leak can be detected by the conventional gas leak alarm and the gas flow can be stopped, while the operation according to the present invention switches from the air-based operation rule to the gas-based operation rule. Is executed, or if the operation rule has already been switched to the correct gas-corresponding operation rule, the switching is not performed, and the above-described measure against the gas leak is merely executed by the gas leak alarm.

Fourth, the gas meter according to the present invention has the above-described second aspect.
In the gas meter described above, the operation control means, after inspecting the function of measuring the gas flow as the gas meter,
The operation control means for performing the operation stop by the time of factory shipment, and after starting the operation stop, performing the operation start when the gas meter is installed in an installation place and actually started to be used. After the operation stop instruction or the operation start instruction is input and the operation rule is switched once, the rule switching means may be connected to the input even if the operation stop instruction or the operation start instruction is input again. On the other hand, it is characterized in that it is an operation rule switching means that does not perform the switching.

That is, in general, after the gas meter has completed its inspection at the time of shipment and is determined to be normal, at the time of shipment, the consumption of the built-in battery during transportation as a product or storage in stock is prevented. For this reason, the operation is stopped in a so-called shipping mode. When the product is purchased as a product and installed at a predetermined installation location, the operation stop state, that is, the shipping mode is released, and the gas meter starts operating again. The operation of inputting a command to shift to the shipping mode and release the shipping mode should be performed by a skilled worker in the factory in order to prevent the consumption of the built-in battery. Can be prevented from being forgotten or erroneously operated to switch the operation rule.

Further, the electromagnetic key device is generally disposed at a position where the operation for inputting the command to shift to and release the shipping mode as described above cannot be performed from the gas meter outer casing (so-called body). However, since the input operation is performed from outside using an electromagnetic key that is compatible with the electromagnetic key device, the risk of mischief from the outside is extremely low even when the device is installed outdoors during actual use. .

As described above, the command input for shifting to the shipping mode or the command input for canceling the shipping mode can be suitably used as the command input to the operation control means. Fifth, the gas meter according to the present invention is the gas meter according to any one of the first to fourth aspects,
The calculation rule switching means includes input means for inputting a command for switching the calculation rule. Through the input means, a plurality of different types of inputs are combined and input in a predetermined combination. A calculation rule switching unit that switches the calculation rule used by the gas flow rate calculation unit from the calculation rule corresponding to one of the gas types different from the air to the calculation rule corresponding to the air only when the calculation is performed. It is characterized by:

That is, all of the techniques described in the first to fourth aspects switch the operation rule corresponding to air to the operation rule corresponding to gas, but conversely, for example, the measurement function of a certain gas meter becomes unstable, and When the seal is closed and re-used, such as when the seal is opened and the internal circuit system is repaired, it is generally required to conduct an inspection again for the suitability as a weighing instrument, similar to the shipping inspection. However, in such a case, it is necessary to switch to the air-based operation rule again. However, if the input operation for such switching can be easily accessed and operated from the outside, the wrong operation rule is easily switched due to mischief, for example.

Therefore, according to the technology described in the fifth aspect, when switching to the operation rule corresponding to air again, a plurality of different types of inputs are set according to a predetermined combination so that no one can operate it. Only when they are combined and input, the switching command is accepted by the gas meter side. That is, a so-called encryption method input is used for the switching command input.

Sixth, the gas meter according to the present invention has the first
5. The gas meter according to any one of claims 4 to 4, wherein the operation rule switching unit includes an input unit for inputting an instruction for switching the operation rule via a communication unit, and the operation rule switching unit transmits the instruction via the communication unit. Only when it is input, the operation rule used in the gas flow rate operation unit is changed from the operation rule corresponding to one of the gas types different from the air to the operation rule corresponding to the air again by the operation rule switching unit. There is provided a gas meter.

In other words, for the same reason as described in the fifth aspect, it is necessary to prevent the operation for switching to the air-based operation rule from being easily operated from the outside. The technique is such that the input operation of the switching command can be performed only through a communication means connected to the gas meter.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the gas meter according to the present invention will be described below in detail with reference to the drawings. (Embodiment 1) As shown in FIG.
A heat flow detecting means for outputting an electric signal in response to a change in a thermal state caused by the gas flow; and calculating a flow rate of the gas flow in accordance with the electric signal output from the heat flow detecting means. A gas meter having a gas flow rate calculating means 102 and a gas flow rate integrating means 103 for integrating the flow rate of the gas flow, wherein the gas flow rate calculating means 102 corresponds to each of a plurality of different gas types including at least air. The gas flow rate calculation means 102 includes a calculation rule holding means 201 for selectively reading out the plurality of calculation rules and holding them so that they can be used. Further, at the time of inspection of at least the function of measuring the gas flow before shipment from the factory as the gas meter, more specifically, until the mode is shifted to a so-called shipping mode, an arithmetic rule corresponding to air is used as the gas type. When measuring the gas flow of a gas type different from the air, more specifically, when the shipping mode is canceled, the gas flow rate calculation means 102 uses the calculation rule corresponding to the gas type. An operation rule switching means 104 for switching the operation rule to an operation rule corresponding to the gas type so as to perform the operation is provided.

Further, the shift to the shipping mode and the release thereof are executed by the operation control means 105. That is, when a command to stop the operation is input from the outside of the gas meter for shifting to the shipping mode, the stop of the operation is notified to the heat flow rate detecting means 101, the gas flow rate calculating means 102, and the gas flow rate integrating means 103. (Ie, it is actually equivalent to stopping the entire function of the gas meter), and when a command to start operation is input to cancel the shipping mode thereafter, the start of operation is determined by the heat flow rate detecting means. The gas meter according to the present embodiment includes an operation control means 105 for executing the operation on the gas flow rate calculation means 101 and the gas flow rate calculation means 102 and the gas flow rate integration means 103. When the operation stops or the operation starts,
In other words, the shift to the shipping mode and its release are executed.

Further, the operation rule switching means 10
4, when the operation stop command is input, the operation rule used in the gas flow rate calculation means is changed from the operation rule corresponding to the air to the operation rule corresponding to one gas of a gas type different from air. Switch. Alternatively, when the operation start command is input, the operation rule may be switched. However, in the present embodiment, it is considered that the probability of occurrence of an operation error or the like is small because the process is closer to the manufacturing site of the gas meter. The above-mentioned switching is employed when shifting to the shipping mode immediately before the transfer.

In this embodiment, as shown in FIG. 2, the heat flow detecting means 101 detects the temperature (T
An upstream temperature sensor 2 for detecting an electric signal (this output is denoted by P1) corresponding to 1), a heater 3 for generating heat by supplying minute electric power and applying the heat to the gas flow 1; A downstream temperature sensor 4 for detecting an electric signal (this output is P2) corresponding to a temperature (T2) of the gas flow 1 heated by the heater 3 on the downstream side of the heater 3; The heater drive circuit 5 that supplies power (that is, passes a current) to drive it (generates heat), and the difference between the electric signals P1 and P2 detected from the two temperature sensors 2 and 4, respectively. ΔP = P2
The main part is constituted by the output difference calculation circuit 6 for calculating -P1. In the present embodiment, such a general configuration is used as the heat flow rate detecting means 101. In addition, for example, a heating wire (not shown) is provided so as to cross the gas flow 1, A minute current is caused to flow through the heating wire, and a change in the resistance value or the like of the heating wire due to the cooling action of the gas flow changes the minute current flowing through the heating wire. It is needless to say that the heat flow detecting means of the method of measuring the flow rate of the gas flow 1 may be used as the heat flow detecting means 101 according to the present invention. Or, more generally, any heat flow detecting means of the so-called thermal mass flow meter type can be used as the heat flow detecting means 101 according to the present invention.

The gas flow rate calculating means 102 calculates the flow rate Q of the gas flow 1 corresponding to the difference between the outputs; ΔP (= P2−P1).
Is the operation rule (Q = Fx (Δ
P)). In the present embodiment, since the output characteristics of the heat flow rate detecting means 101 show extremely good linearity with respect to the flow rate of the gas flow 1, the above calculation rule; Q = Fx (ΔP) Is assumed to follow the simplest proportional equation or linear function. That is,
In a formula, Q = k · ΔP or Q = k · ΔP + b. Here, k is each straight line 301, in the graph of FIG.
It is a coefficient indicating the slope of 302 and 303, and b is the y-intersection in the graph. However, in the following description, for the sake of simplicity, the case where b is omitted and the simplest proportional equation Q = k · ΔP is used as the above-mentioned calculation rule will be described.

Here, the straight line 301 in FIG.
Is a graph when the flow of LPG is measured, and a straight line 302 is a graph when the flow of the same LPG is measured under a condition different from that of the straight line 301, and a straight line 303 is when the flow of air is the straight line 302. Graphs when measured under the same conditions as in FIG. The horizontal axis of the coordinates of the graph shows the flow rate Ql / h. The vertical axis shows the output difference ΔP as a dimensionless quantity using ΔP at the maximum value of the flow rate Q of 21 l / h as a reference value.

As is apparent from FIG. 3, the gas flow 1
Are equal, for example, the actual (true) flow rate Qr = 9 l / h plotted on the horizontal axis in FIG.
Looking at the case of the above, in the measurement of air, the temperature sensor 2,
4 (vertical axis) is about 50, while LP
In the measurement of G, the output from the temperature sensors 2 and 4 is about 1
It is clearly visible that it is 50. Therefore,
In order to fulfill the substitute of flowing gas by flowing air through the gas meter and measuring and calculating the flow rate, the above calculation rule; the coefficient k in Q = k · ΔP; That is, it must be set to be three times the coefficient. That is, if the coefficient used in LPG is kg and the coefficient used in air is ka, then k
Both are set so that the relationship of a = 3 kg holds. That is, the coefficient used in the LPG; kg may be a conventional one, whereas the coefficient which is switched by the switching operation according to the present invention and is used corresponding to the air; ka = 3
kg. Such data is held (stored) in the arithmetic rule holding means 201 described above.

The operation rules held (stored) in the operation rule holding means 201, that is, the information of the coefficients ka and kg in the present embodiment, correspond to the air before shifting to the so-called shipping mode. The arithmetic rule or coefficient k
a is selected and used by the gas flow rate calculation means 102 in the calculation. Then, when an input of an instruction to shift to the shipping mode is input from the outside, based on the input, the operation rule switching unit 104 causes the other operation rule held (stored) in the operation rule holding unit 201, A coefficient used in the LPG; kg is read out, and is switched so as to be used for the calculation in the gas flow rate calculation means 102.

At this time, as an input means for inputting a command to stop operation from outside the gas meter for shifting to the shipping mode, an electromagnetic key device is generally placed at a position where it cannot be operated from the gas meter outer casing (so-called body). The electromagnetic key device 501 is provided from outside.
Since the input operation is performed using the electromagnetic key 502 that conforms to the above, the gas meter according to the present invention also uses such input means as an instruction input to the operation control means 105 and uses the input means as the operation rule switching. It can also be suitably used as an input of an instruction for causing the means 104 to execute the above-described switching of the operation rule.

Then, once the switching from the air-based operation rule to the gas-based operation rule is performed, the operation rule switching means 104 records the execution of the switching as a history, and thereafter, the same operation as described above is performed. Even if the input of the command to shift to the shipping mode is input from outside, the command is not accepted and the switching of the arithmetic rule is not executed.

The gas flow rate calculating means 102, the gas flow rate integrating means 103, the calculation rule switching means 104, the operation control means 105, and the calculation rule holding means 201 are built in a gas meter which has been widely used in recent years. CPU (not shown) such as a microcomputer and its peripheral circuit (EE
A storage element such as a PROM). In the present embodiment, such a CPU and peripheral devices are used. Alternatively, it goes without saying that the above-described outline configuration may be constructed by combining discrete circuit elements and the like.

The gas meter according to the present embodiment has, of course, a lighter amount of gas used as the original gas meter and further detailed mechanisms for displaying the gas amount and an arithmetic circuit system. Details and illustrations of the same functions as those of the conventional gas meter are omitted for simplification of the description. Although not shown and described, other than the configuration of the main part according to the present invention shown in FIG. 1, for example, a mechanical numerical counter for displaying an integrated value of gas consumption, a segment type for displaying digital numerical values, or a dot type. Display means such as a matrix type liquid crystal panel, gas leak alarm device that detects the occurrence of an abnormality such as gas leakage and warns of it, or shuts off gas supply in response to it Needless to say, it also has the same devices and circuits as the conventional gas meter.

Next, an outline of the operation of the gas meter of the first embodiment according to the present invention, in which the main parts are configured as described above, will be mainly described, particularly focusing on the switching operation of its operation rule.
This will be described based on the flowchart of FIG. This gas meter is first completed in a manufacturing factory as hardware of the gas meter itself. The built-in CPU (not shown) is in a state where an OS (operation software) is already installed. However, at this stage, it is needless to say that the operation program has not yet been installed in terms of the function as the measuring instrument, and therefore, the appropriateness of the function as the measuring instrument has not been checked.

Subsequently, software for operating as a gas meter, that is, an operation program is installed in the CPU. That is, the gas flow rate calculation means 102, the gas flow rate integration means 103, the calculation rule switching means 104, the operation control means 105, and the calculation rule holding means 20 described above.
The operation program is installed in a peripheral device such as a CPU and its external storage element, which substantially constructs the device 1 therein. Thus, a gas meter that can actually function is completed.

The operation program installed at this time is determined such that an operation rule corresponding to air is selected as an operation rule used when performing a flow rate calculation in the gas flow rate calculation means 102 as an initial state (initial value). Information is also written. That is, in the operation program installed at this time, the gas flow rate calculating means 102 is included.
Calculation rule holding means 201 as a calculation rule used in the calculation by
A flag F = 0, which is information for designating that the operation rule corresponding to air is first selected, read, and used from among the operation rules held in the program, is written. When this operation program is installed, (S1), the flag F
= 0 is set (s2).

Subsequently, the gas meter is inspected for proper functioning as a measuring instrument. That is, when air is used as a substitute for a gas such as LPG and the air is supplied to the gas meter, the gas flow rate is calculated by the gas flow rate calculating means 102 by the gas flow rate calculating means 102. As a calculation rule (coefficient in this case) used at the time of execution, the calculation rule switching means 104 selects a coefficient ka which is a calculation rule corresponding to air (s4), and using this coefficient ka, a relational expression: Q = ka Calculation of the flow rate value is performed based on ΔP (s5), and a measurement value almost equivalent to the case where measurement is performed by actually flowing LPG is calculated. Then, the inspector determines whether or not the measured value is within a proper range (within an allowable error).

In this manner, the inspection as to whether the function as a measuring instrument is appropriate, that is, the so-called shipping test evaluation inspection is performed, and the gas meter determined to be appropriate here is switched to the shipping mode, and Go, shipped. When the mode is switched to the shipping mode, a switching command for shifting to the shipping mode is input to the operation control means 105 as described above.
Also in step 04, the operation rule is diverted as the input for switching the operation rule (Y in s6), and the selected operation rule is changed from the above ka to k.
Switch to g (s7).

Further, in order to leave a history that the switching from ka to kg has been performed, F = 1 is set instead of the flag F = 0 (s8). Then, the operation control means 105 follows the original switching command.
Are the heat flow rate detecting means 101 and the gas flow rate calculating means 10
2, gas flow integrating means 103, arithmetic law switching means 104,
The operation of the entire gas meter such as the arithmetic rule holding means 201 is stopped (s9), and the system enters a so-called shipping mode.

When the gas meter is shipped and installed at the place of use, a switching command for canceling the shipping mode is input (Y in s10), and the gas meter starts operating again (s11). Until then, it is needless to say that the switching command input is awaited and the shipping mode, that is, the operation stop state is continued (N in s10).

When the operation of the gas meter is restarted in this way, it is first determined whether the value set as the flag F is 0 or 1 (s3), and the set value is set;
If F = 1, it is assumed that the switching of the calculation rule has already been executed, and the calculation rule switching means 104 selects a coefficient kg such as LPG, which is a calculation rule corresponding to a genuine actually used gas ( s12) Using this coefficient kg, the flow rate value of the actually used gas is calculated based on the relational expression; Q = kg · ΔP (s13), and the actually measured flow rate value actually measured by flowing the LPG is calculated. You. Then, the flow value is further integrated by the gas flow integration means 103 to calculate the integrated usage amount of the gas (s14). As a method of calculating the integrated value of the gas, a method similar to the conventional technique may be suitably used. For example, it goes without saying that the flow value may be monitored at specific time intervals, and the flow value at that time may be sequentially integrated to calculate and update the integrated value of the gas flow.

(Embodiment 2) In the gas meter of the first embodiment, based on the input of the switching command input to the operation control means 105, the calculation rule switching means 104 performs the flow rate calculation in the gas flow rate calculation means 102. Although the operation rule used when performing was changed,
In the second embodiment, in addition to the input of the switching command from the outside via the operation control means 105 as described above, even if such a switching command is input, the operation rule is changed from the air handling. The characteristic point is that the calculation rule switching means 104 automatically switches to the calculation rule corresponding to gas even when the operation rule cannot be switched to gas.

That is, in the gas meter according to the second embodiment, as shown in FIG. 5, in the gas meter according to the first embodiment, the gas flow rate calculation means 102 uses a calculation rule corresponding to the air. Sometimes, the operation rule ka
Is compared with a predetermined threshold value Qth to determine that the flow rate value Q is equal to the threshold value Qt.
If it is determined that the value is greater than h, the calculation rule kx used in the gas flow rate calculation means 102 is calculated from the calculation rule ka corresponding to the air by a calculation corresponding to one appropriate gas type different from air. The calculation rule switching means 1 to the rule kg
Gas operation law abnormality determining means 1 to be switched by the control unit 04
06 is a gas meter further provided. That is, in the gas meter of the present embodiment, the switching of the operation rule depends not only on the external input, but also when the switching by the external input is not performed, or the switching operation failure due to some disturbance or the like. In the case where an error occurs, the calculation rule switching means 104 automatically determines a gas flow such as LPG which is different from air and automatically switches to a calculation rule corresponding to the gas. It has been added further. Other configurations and functions are the same as those in the first embodiment. Note that, for simplification of description, the same reference numerals are given to the components and operation steps in the present embodiment that are the same as those in the first embodiment.

As shown in the schematic flowchart of FIG.
In the gas meter according to the second embodiment, s1 to s
Up to 9, that is, until it is manufactured at a factory, installed with an operation program, subjected to inspection, determined to be appropriate, and shipped, it is handled and functions in the same manner as in the first embodiment.

When the gas meter is installed at the place of use and the operation is resumed (s11), the operation rule (this is kx) corresponding to the already set flag (this is Fx) is calculated. The switching means 104 selects and reads out from the calculation rule holding means 201 (s15), and the gas flow rate calculation means 102 calculates the gas flow rate Q using this. That is, at this time, the gas flow rate calculation means 102 calculates the flow rate value using the calculation rule kx corresponding to Fx, ie, ka or kg; Q = kx · ΔP (s16). Originally, at this time, kx = kg should have been uniquely determined. However, in this embodiment, it is assumed that kx becomes ka instead of kg due to some cause such as disturbance. In s15, kx is deliberately described as kx = kg, which is not definitive.

Subsequently, the flow value Q calculated by the above calculation is compared with a threshold value Qth predetermined as an upper limit value within a normal flow value range (s17), and the calculated flow value Q When Q satisfies Q ≧ Qth (Y in s17), an abnormal value exceeding the range of the normal flow rate value is calculated, and the calculation which caused such abnormal value calculation is performed. It is determined that the rule, that is, the coefficient kx, actually uses ka here (s18).

Furthermore, the fact that such an erroneous coefficient is used (selected) means that the flag Fx is also likely to have an erroneous value, so that F = 1 is also set for this flag Fx. It is concluded that it is necessary to set securely. Therefore, when Q ≧ Qth as described above, F = 1 is set again as in s7 (s1
9). As a result, F = 1 can be surely set, and the operation can be reliably switched to the appropriate calculation rule, that is, the coefficient kg.

In addition, as described above, in this case, the integrated flow value is reset (s20). Therefore, the integrated flow value of the erroneous flow value calculated by using the inappropriate coefficient ka up to that time is calculated as Can be erased. Then, after s3, a new appropriate operation rule, that is, a coefficient kg, is used (s1
2) When the gas flow rate integration is started (s13), the improper integrated value up to that point is automatically deleted in s20 as described above, and thereafter, the flow rate calculated based on the correct calculation rule Only the integrated value of the values can be recorded.

On the other hand, if the calculated flow rate value Q satisfies Q ≦ Qth in s17 (N of s17), the calculated value is a normal value.
Is determined to have already been used, and the measurement, calculation, and integration of the gas flow rate based on the calculation rule are continued (s
13-).

Here, the threshold value Qth predetermined as the upper limit value within the range of the normal flow rate value will be described. Heat flow detecting means 10 used in gas meter
The electric signal detected by 1 generally has significantly different numerical characteristics between fuel gas such as LPG at the time of actual use of the gas meter and air at the time of shipping inspection. The difference is, for example, between LPG and air,
With respect to the electric signal (that is, the output difference in this embodiment; ΔP) detected by (the temperature sensors 2, 4, etc.), the output difference of LPG is three times as large as that of air for the same actual flow rate. Will be. As described above, since the measurement results are significantly different, it is necessary to switch the operation rule as described above according to the present invention. The operation rule k corresponding to the air, even when the gas such as LPG is actually used, is actively utilized by utilizing the remarkably significant difference from the above.
If a is used, it can be determined to be abnormal with considerable accuracy.

That is, in the case of the flow of the LPG gas, for example, the heat flow detecting means 101 detects ΔP about three times as large as the flow of the air as shown in FIG. In other words, to use air as a substitute for LPG and perform a flow measurement test that is almost equivalent to actual use,
The measured value (ΔP) calculated on the basis of the electric signal detected by the heat flow detecting means 101 must be approximately three times the value. If the calculation rule ka corresponding to such air is used, When the flow rate of the LPG is measured and calculated using the LPG as it is without switching to kg, the flow rate value Q calculated at that time is first determined even if the actual flow rate Qr of the actual gas is the same as that of the air. Flow rate detecting means 1
The electric signal (output difference; ΔP) detected at 01 is three times that of the air. Moreover, by using the calculation rule ka corresponding to air, a value that is three times the value of the electric signal (ΔP) is finally calculated as a calculation value of the flow rate Q. This means that the flow rate value Q is always calculated to be three times that when the gas flow is normally calculated using the calculation rule corresponding to the gas. In other words, three times the abnormal value that cannot be considered in a normal state should always be calculated. Therefore, when such an abnormal value is calculated, it is determined to be abnormal by the gas calculation rule abnormality determination means 106, and the calculation rule kg is automatically switched to the calculation rule kg corresponding to the original gas.

For example, taking the case shown in FIG. 3 as an example, when the gas flow rate calculating means 102 calculates the LPG flow rate using the coefficient ka, the gas flow rate calculating means 102 calculates the LPG gas flow rate using the coefficient kg. The flow rate value is calculated three times as much as that in the case of performing the operation. Therefore, when considered conversely, the true flow rate Qr of the LPG is equal to the measurement limit (here, 21
If the value exceeds 1/3 of 1 / h), the calculated flow rate value must be an abnormal value exceeding the measurement limit of the gas meter. The probability that the gas will be used at the time of actual use at a flow rate exceeding 1/3 (that is, 7 l / h) of the measurement limit (21 l / h) with such a gas meter is considerably high. ka
When the calculation is performed using the above, an abnormal value exceeding the measurement limit as described above and which is impossible in a normal state should be generated with high probability and continuously. Therefore, the threshold value Qth for determining such an abnormal value
For example, in the example of FIG. 3, the measurement limit of the gas meter may be set to 21 l / h, that is, Qth = 21 l / h. Or a value less than that, for example, 18 l
Considering, for example, that the chance of using gas in the flow rate range of / l / h or more is actually small, the coefficient ka is used even when such a flow value of 18 l / h or more is calculated. L
It is highly likely that the PG flow rate is calculated. Therefore, in consideration of such matters, the threshold value Qth is set to a value lower than the above-mentioned value of 21 l / h, for example, Qth = 181
Needless to say, it may be set to / h.

In this embodiment, as described above, the automatic switching function is activated from the start of the shipping mode after the shipment inspection. However, the automatic switching function is already activated from the factory inspection time. You may do it. However, in this case, if Qth is set to be equal to or less than the measurement limit of the gas meter, the flow rate value calculated using the calculation rule corresponding to air at the time of inspection using the air as a substitute is 18 l / h. In this case, the above-described automatic switching function may function while the inspection is being performed, and a situation may occur in which the calculation rule corresponding to the gas is switched during the inspection. In such a case, the Qth may be used. May be set to be equal to or more than the measurement limit of the gas meter (that is, 21 l / h in this case).

In the second embodiment, the case where the gas operation law abnormality judging means 106 is additionally provided as a so-called fail-safe function to the configuration of the gas meter of the first embodiment has been described. The command input for the switching operation of the operation rule does not depend on the external input such as the switching of the shipping mode, and the actual use of the gas is automatically determined by using the gas operation rule abnormality judging means 106. It is needless to say that the calculation rule of the flow rate may be automatically switched based on (not depending on the external input).

In each of the above-described embodiments, as is clear from the flowcharts described above, the operation rule switching unit 104 receives an instruction to stop the operation or an instruction to start the operation and changes the operation rule from ka to kg. After switching once, even if the operation stop instruction or the operation start instruction is input again, the input is not switched. That is, the first and second embodiments according to the present invention
Once the gas meter according to the embodiment is shipped, installed at the place of use, and started to be used, the operation rule cannot be rewritten from ka to kg by an external operation.

However, on the contrary, there is a case where it is necessary to return the operation rule from kg to ka again to carry out a retest or the like. Therefore, in such a case, the arithmetic rule switching means 104 is provided with an input means (not shown) for inputting a command for switching the arithmetic rule, and a plurality of different types of input are provided through the input means. Is changed from the calculation rule kg corresponding to the gas to the calculation rule ka corresponding to the air only when the calculation rule kx used in the gas flow rate calculation means 102 is input only in combination with a predetermined combination. Good. That is, by adopting such an encryption method, the operation rule cannot be easily switched from outside. As the input means of the above-mentioned encryption method,
For example, by suitably using a numeric keypad using a touch sensor, the order of the input data is compared with a predetermined order of cryptographic data, and when the order matches, the instruction is switched to an operation rule switching instruction. What is necessary is just to recognize it as an input, and to switch it. Conventional technology can be suitably used for such an encryption function itself. Alternatively, in order to prevent the operation rule from being easily switched from the outside, the operation rule switching unit 104 inputs a command for switching the operation rule kx via the communication unit (not shown). An input unit (not shown) is further provided, and only when the command is input via the communication unit, the operation rule kx used in the gas flow rate operation unit 102 is changed from the operation rule kg corresponding to the gas to the The calculation rule ka corresponding to the air may be switched again.

In each of the above embodiments, the case where the coefficients ka and kg are actually switched as an operation rule has been described. However, this is because the measurement characteristics of the heat flow rate detecting means 101 used in the above embodiments are extremely low. Since it has good linear characteristics (linearity), it was possible to calculate the flow rate using the simplest calculation rule as described above, ie, the proportional equation; Q = kx · ΔP. This is because the switching of the rule should have been substantially effected by switching only the coefficient kx. In other words, the measurement characteristics of the heat flow rate detection means 101 do not always show extremely good linearity as in the above-described embodiment, and may show non-linear characteristics. As an operation rule, it is necessary to use an operation rule expressed as Q = Fx (ΔP) as a function of a general relationship of ΔP → Q, instead of the proportional expression as described above. Therefore, in such a case, assuming that the calculation rule corresponding to air is Q = Fa (ΔP) and the calculation rule corresponding to gas is Q = Fg (ΔP), these calculation rules are shown in the above embodiments. Needless to say, the switching may be performed in the same manner as the switching of the coefficient kx.

[0066]

As described in the detailed description above, according to the present invention, at the time of product test evaluation at the time of shipment, a flammable gas such as LPG at the time of actual use is not used, but is used. It is possible to provide a gas meter of the thermal mass flow meter type, which can substitute for air and can always calculate the flow rate using an operation rule that accurately corresponds to combustible gas such as LPG in actual use. it can.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an outline of a configuration of a gas meter according to a first embodiment.

FIG. 2 is a diagram showing an outline of a configuration of a heat flow detecting unit 101.

FIG. 3 is a diagram showing a comparison between air and LPG each having an output (output difference; ΔP) detected by a temperature sensor corresponding to an actual fluid flow rate Qr.

FIG. 4 is a flowchart illustrating an outline of an operation of the gas meter according to the first embodiment.

FIG. 5 is a diagram illustrating an outline of a configuration of a gas meter according to a second embodiment.

FIG. 6 is a flowchart illustrating an outline of an operation of the gas meter according to the second embodiment.

[Explanation of symbols]

 Reference Signs List 101 heat flow detecting means 102 gas flow calculating means 103 gas flow integrating means 104 calculation rule switching means 105 operation control means 201 calculation law holding means

Claims (6)

[Claims] 1. A heat flow detecting means for outputting an electric signal in response to a change in a thermal state caused by a gas flow, and a flow rate of the gas flow in response to an electric signal output from the heat flow detecting means And a gas flow rate integrating means for integrating the flow rate of the gas flow, wherein the gas flow rate calculating means includes a plurality of gas types respectively corresponding to a plurality of different gas types including at least air. Gas flow rate calculating means that holds the calculation rule of the above, and uses a calculation rule corresponding to air as the gas type at least until an inspection of a function of measuring the gas flow before shipment from a factory as the gas meter. When measuring a gas flow of a gas type different from the air, the gas flow rate calculation means may perform the calculation using a calculation rule corresponding to the gas type. , Gas meter, characterized by comprising a calculating rule switching means for switching the operation rule in the calculation rule corresponding to the gas type. 2. The gas meter according to claim 1, wherein when an operation stop command is input from outside, the operation stop is notified to at least the heat flow rate detection means, the gas flow rate calculation means, and the gas flow rate integration means. Executing, further comprising an operation control means for executing the operation start at least to the heat flow rate detection means, the gas flow rate calculation means, and the gas flow rate integration means when an operation start instruction is input from the outside. When the operation stop command or the operation start command is input, the operation rule switching unit changes the operation rule used by the gas flow rate operation unit from the operation rule corresponding to the air to the air. A gas meter, which is a calculation rule switching unit that switches to a calculation rule corresponding to one of gas types. 3. The gas meter according to claim 1, wherein the gas flow rate calculating means conducts a gas different from the air and measures a flow rate of the gas when the gas flow rate calculating means measures a flow rate of the gas. When calculating the flow rate by using the flow rate value calculated according to the calculation rule and a predetermined threshold, the calculated flow value is a value larger than the threshold value When it is determined that there is, the calculation rule used in the gas flow rate calculation means is changed from the calculation rule corresponding to the air to the calculation rule corresponding to one of the gas types different from the air. A gas meter further comprising a gas calculation law abnormality determining means for switching by a law switching means. 4. The gas meter according to claim 2, wherein the operation control means has a function of measuring a gas flow as the gas meter, and receives an instruction to execute the operation stop by the time of shipment from a factory. An operation control means for executing an operation stop and executing the operation start when the operation start instruction is inputted when the operation stop is executed and the gas meter is installed in an installation place and the actual use is started. The operation rule switching means may be configured such that after the operation stop instruction or the operation start instruction is input and the operation rule is switched once, the operation stop instruction or the operation start instruction is input again. A gas meter, which is an operation rule switching unit that does not perform the switching for the input. 5. The gas meter according to claim 1, wherein the operation rule switching unit includes an input unit that inputs a command for switching the operation rule, and Only when a plurality of different types of inputs are combined and input according to a predetermined combination, the calculation rule used by the gas flow rate calculation means is calculated according to one of the gas types different from the air. A gas meter as a calculation rule switching means for switching again from a rule to a calculation rule corresponding to the air. 6. The gas meter according to claim 1, wherein the operation rule switching unit includes an input unit that inputs a command for switching the operation rule through a communication unit, and the communication unit switches the operation rule. Only when the command is input through the means, the calculation rule used in the gas flow rate calculation means is changed from the calculation rule corresponding to one of the gas types different from the air to the calculation rule corresponding to the air. A gas meter, which is an operation rule switching unit that switches again.