JP2002350205A - Flow measuring device using flow sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow measuring device using a flow sensor capable of precisely determining the abnormality of a sensor. SOLUTION: This flow sensor 1 is provided with a heater 4 for heating gas flowing through a gas passage, an upstream temperature sensor 8 disposed in the upstream of gas from the heater 4, a downstream temperature sensor 5 disposed in the downstream of gas from the heater 4, a right side temperature sensor 11 and left side temperature sensor 13 disposed substantially in the direction intersecting perpendicularly to the flowing direction of the gas to the heater 4, and a support board 2. This flow measuring device calculates a flow rate of gas according to the output of each temperature sensor in the on-state of the heater 4 using the flow sensor 1. The flow measuring device is provided with a determining means 48 for determining abnormality of one sensor of the respective temperature sensors when the calculated gas flow exceeds a designated threshold and pressure lowering of the gas passage is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow measuring device,
In particular, the present invention relates to a flow rate measuring device using a flow sensor capable of determining an abnormality of the flow sensor.

[0002]

2. Description of the Related Art Conventionally, a flow rate measuring device using a flow sensor is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-12988.

A flow sensor used in this type of flow rate measuring device is, for example, a micro-heater for heating a gas flowing in a gas flow path, and is disposed upstream of the gas with respect to the micro-heater, and detects the temperature of the gas. An upstream thermopile that acts as an upstream temperature sensor that outputs a temperature detection signal, and is disposed downstream of the gas with respect to the micro heater,
A downstream thermopile that functions as a downstream temperature sensor that detects the temperature of the gas and outputs a temperature detection signal, and is disposed in a direction substantially perpendicular to the gas flow direction with respect to the micro heater,
A right-side thermopile that functions as a right-side temperature sensor that detects the temperature of the gas and outputs a temperature detection signal, and a side facing the right-side thermopile across the microheater, in a direction substantially perpendicular to the gas flow direction with respect to the microheater. A left thermopile disposed as a left temperature sensor that detects a gas temperature and outputs a temperature detection signal, and a microheater, an upstream thermopile, a downstream thermopile, a right thermopile, and a support substrate that supports the left thermopile are provided. It is a micro flow sensor.

In this flow rate measuring device, the gas flow rate is calculated based on the temperature detection signals from the downstream thermopile and the upstream thermopile, and the gas flow rate is calculated based on the temperature detection signals from the right thermopile and the left thermopile. The species is determined.

FIG. 9 is a block diagram of an example of a flow rate measuring device using the above-mentioned micro flow sensor. The flow rate measuring device includes a differential amplifier 33 that amplifies a difference signal between a second temperature detection signal from the downstream thermopile 5 of the microflow sensor and a first temperature detection signal from the upstream thermopile 8 of the microflow sensor. An amplifier 35a for amplifying the right temperature detection signal from the right thermopile 11 of the microflow sensor, an amplifier 35b for amplifying the left temperature detection signal from the left thermopile 13 in the microflow sensor 1, and a microcomputer (hereinafter referred to as a microcomputer). ) 40.

The microcomputer 40 includes an adder 45 for adding the right temperature detection signal from the amplifier 35a and the left temperature detection signal from the amplifier 35b, a second temperature detection signal obtained by the differential amplifier 33, and a first temperature. A dividing unit 47 for dividing a difference signal from the detection signal by an addition signal output from the adding unit 45; a flow calculating unit 41 for calculating a gas flow rate based on the dividing signal output from the dividing unit 47; It is provided with a fluid property value calculation unit 43 that calculates property values such as thermal conductivity, specific heat, viscosity, and density of the gas based on the output addition signal.

Next, a flow rate measuring method realized by the flow rate measuring device shown in FIG. 9 will be described with reference to a flowchart shown in FIG.

First, the micro-heater is heated by a driving current based on an external pulse signal (step S5).
1), a second temperature detection signal is output from the downstream thermopile 5, and a first temperature detection signal is output from the upstream thermopile 8 (step S53). 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. Next, the differential amplifier 33 amplifies a difference signal between the second temperature detection signal from the downstream thermopile 5 and the first temperature detection signal from the upstream thermopile 8 (Step S55).

The adder 45 adds the right temperature detection signal from the amplifier 35a and the left temperature detection signal from the amplifier 35b to obtain an addition signal (step S57).
Next, the divider 47 divides the amplified difference signal obtained in step S55 by the addition signal obtained in step S57 to obtain a division signal (step S59).

[0010] Subsequently, the flow rate calculation unit 41 determines in step S5.
The accurate flow rate of the gas is calculated based on the division signal obtained in step 9 (step S61). Further, the fluid property value calculation unit 4
3 is the sum of the addition signal obtained in step S57 and step S57.
Based on the accurate flow rate of the gas calculated in 61, the physical properties of the gas, such as the thermal conductivity, specific heat, viscosity, and density of the gas, are calculated (step S63).

[0011]

However, in the conventional flow rate measuring apparatus using the above-mentioned flow sensor, each temperature sensor, that is, each thermopile fails due to some abnormality such as disconnection or the like, and a large flow rate that should not flow originally can be obtained. Even when measurement is performed, there is no means to notify the occurrence of abnormality,
There is a problem that users and gas utilities cannot notice.

Accordingly, an object of the present invention is to provide a flow rate measuring device using a flow sensor capable of accurately determining a sensor abnormality by focusing on the above-described problems.

[0013]

According to a first aspect of the present invention, there is provided a heater for heating a gas flowing through a gas flow path, the heater being disposed upstream of the gas with respect to the heater. An upstream temperature sensor, a downstream temperature sensor disposed downstream of the gas with respect to the heater, a right temperature sensor disposed substantially perpendicular to the gas flow direction with respect to the heater, and the heater A left-side temperature sensor disposed on the side opposite to the right-side temperature sensor in a direction substantially perpendicular to the gas flow direction with respect to the heater, the heater, the upstream-side temperature sensor, and the downstream-side temperature sensor A flow sensor including a right temperature sensor and a support substrate supporting the left temperature sensor, and calculating a gas flow rate based on an output of each temperature sensor when the heater is turned on. In the quantity measuring device, when the calculated gas flow rate exceeds a predetermined threshold value and there is no pressure drop in the gas flow path, a determination unit that determines that any of the temperature sensors is abnormal is provided. A flow rate measuring device using a flow sensor, comprising:

According to the first aspect of the present invention, a heater for heating the gas flowing through the gas flow path, an upstream temperature sensor disposed on the upstream side of the gas with respect to the heater, and a downstream of the gas with respect to the heater are provided. A downstream temperature sensor disposed on the side, a right temperature sensor disposed in a direction substantially orthogonal to the gas flow direction with respect to the heater, and a side opposed to the right temperature sensor with the heater interposed therebetween. Using a left side temperature sensor disposed in a direction substantially perpendicular to the gas flow direction, and a flow sensor including a heater, an upstream side temperature sensor, a downstream side temperature sensor, a right side temperature sensor, and a support substrate that supports the left side temperature sensor. In a flow rate measuring device that calculates the gas flow rate based on the output of each temperature sensor when the heater is turned on, the calculated gas flow rate exceeds a predetermined threshold value and the pressure in the gas flow path does not decrease. If, and a abnormality determination means any of the sensors in the temperature sensors.

[0015] This makes it possible to judge whether the flow sensor is abnormal and to prevent erroneous flow measurement due to the sensor abnormality.

The invention according to a second aspect of the present invention has been made to solve the above-mentioned problem, and further comprises an alarming means for alarming the sensor abnormality when the determining means determines that the sensor is abnormal. In a flow rate measuring device using a flow sensor.

According to the second aspect of the present invention, when the determination means determines that the sensor is abnormal, there is provided an alarm means for alarming the sensor abnormality.

This makes it possible to judge whether the flow sensor is abnormal, to prevent erroneous flow measurement due to the sensor abnormality,
The sensor abnormality can be notified to the user or the gas company, and the device can be operated safely.

According to a third aspect of the present invention, there is provided an electric vehicle comprising: a shut-off means for shutting off the gas flow path when the judgment means judges that the sensor is abnormal. 1. A flow measuring device using the flow sensor according to 1.

According to the third aspect of the present invention, there is provided the shutoff means for shutting off the gas flow path when the judgment means judges that the sensor is abnormal.

Thus, it is possible to judge the abnormality of the flow sensor, to prevent erroneous flow rate measurement due to the sensor abnormality,
It is possible to operate the device on the safe side.

According to a fourth aspect of the present invention, there is provided a heater for heating a gas flowing through a gas flow path, and an upstream temperature sensor disposed upstream of the gas with respect to the heater. A downstream temperature sensor disposed downstream of the gas with respect to the heater, a right temperature sensor disposed substantially perpendicular to the gas flow direction with respect to the heater, and the right side of the heater with the heater interposed therebetween. On the side facing the temperature sensor, a left temperature sensor disposed in a direction substantially perpendicular to the gas flow direction with respect to the heater, the heater, the upstream temperature sensor, the downstream temperature sensor, the right temperature sensor, and A flow measuring device that calculates a gas flow rate based on an output of each of the temperature sensors when the heater is turned on, using a flow sensor including a support substrate that supports the left temperature sensor. When the calculated flow rate of the gas exceeds a predetermined threshold, the shutoff means for shutting off the gas flow path, and when the flow rate is measured to be present after the shutoff by the shutoff means, A flow rate measuring device using a flow sensor, characterized by comprising a determination means for determining that one of the temperature sensors is abnormal.

According to the fourth aspect of the present invention, the heater for heating the gas flowing through the gas flow path, the upstream temperature sensor disposed on the upstream side of the gas with respect to the heater, and the downstream of the gas with respect to the heater A downstream temperature sensor disposed on the side, a right temperature sensor disposed in a direction substantially perpendicular to the gas flow direction with respect to the heater, and a side opposed to the right temperature sensor across the heater with respect to the heater. Using a left temperature sensor disposed in a direction substantially perpendicular to the gas flow direction, a heater, an upstream temperature sensor, a downstream temperature sensor, a flow sensor including a support substrate that supports the right temperature sensor and the left temperature sensor, In a flow rate measuring device that calculates a gas flow rate based on an output of each temperature sensor when a heater is turned on, shuts off a gas flow path when the calculated gas flow rate exceeds a predetermined threshold. And the step, if the flow rate is measured and there after interruption by blocking means, and an abnormality and determining means of any of the sensors in the temperature sensors.

Thus, it is possible to judge the abnormality of the flow sensor, and it is possible to prevent the erroneous flow rate measurement due to the sensor abnormality.

According to a fifth aspect of the present invention, there is provided an alarm device for alarming a sensor abnormality when the determination unit determines that the sensor is abnormal. In a flow rate measuring device using a flow sensor.

According to the fifth aspect of the present invention, when the determination means determines that the sensor is abnormal, there is provided an alarm means for alarming the sensor abnormality.

This makes it possible to judge whether the flow sensor is abnormal, to prevent erroneous flow rate measurement due to the sensor abnormality,
The sensor abnormality can be notified to the user or the gas company, and the device can be operated safely.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a flow rate measuring device using a flow sensor according to the present invention. This flow rate measuring device amplifies a difference signal between the second temperature detection signal from the downstream thermopile 5 in the microflow sensor and the first temperature detection signal from the upstream thermopile 8 in the microflow sensor when the heater is turned on. Dynamic amplifier 33 and an amplifier 35a for amplifying the right temperature detection signal from the right thermopile 11 of the micro flow sensor
And the left thermopile 13 in the micro flow sensor 1
35b that amplifies the left-side temperature detection signal from the microcomputer, the microcomputer 40, and the pressure sensor 5 that detects the pressure of the gas flow path.
1, a display unit 52 as a part of alarm means, and a memory 5
3, a shutoff valve 54 for shutting off the gas flow path, and a notification unit 55 as a part of alarm means for notifying the gas management center of the gas company.

The microcomputer 40 includes an adder 45 for adding the right temperature detection signal from the amplifier 35a and the left temperature detection signal from the amplifier 35b, a second temperature detection signal obtained by the differential amplifier 33, and a first temperature. A dividing unit 47 for dividing a difference signal from the detection signal by an addition signal output from the adding unit 45; a flow calculating unit 41 for calculating a gas flow rate based on the dividing signal output from the dividing unit 47; It is configured to include a fluid property value calculation unit 43 that calculates property values such as thermal conductivity, specific heat, viscosity, and density of a gas based on the added signal to be output, and a determination unit 48 as determination means.

FIG. 2 and FIG. 3 are a configuration diagram and a sectional view of a micro flow sensor used in the flow rate measuring device of FIG. In FIG. 2, a micro flow sensor 1 includes a Si substrate 2, a diaphragm 3, a micro heater 4 made of platinum or the like formed on the diaphragm 3, and a downstream temperature sensor formed on the diaphragm 3 downstream of the micro heater 4. A power supply terminal 6A for supplying a drive current from a power supply (not shown) to the downstream thermopile 5
6B, an upstream thermopile 8 as an upstream temperature sensor formed on the diaphragm 3 on the upstream side of the microheater 4, and first output terminals 9A and 9B for outputting a first temperature detection signal output from the upstream thermopile 8 And second output terminals 7A and 7B for outputting a second temperature detection signal output from the downstream thermopile 5.

The micro flow sensor 1 is disposed in a direction substantially perpendicular to the gas flow direction (the direction from arrow P to arrow Q in FIG. 3) with respect to the micro heater 4, and detects the physical property value of the gas. A right thermopile 11 serving as a right temperature sensor for outputting a right temperature detection signal (corresponding to a third temperature detection signal); a third output terminal 12A for outputting a right temperature detection signal output from the right thermopile 11;
12B and a left-side temperature sensor that is disposed in a direction substantially perpendicular to the gas flow direction with respect to the micro-heater 4, detects a physical property value of the gas, and outputs a left-side temperature detection signal (corresponding to a third temperature detection signal). Left thermopile 13, fourth output terminals 14A and 14B for outputting a left temperature detection signal output from left thermopile 13, resistors 15 and 16 for obtaining gas temperature, and gas temperature from resistors 15 and 16 Output terminals 17A and 17B for outputting signals are provided.

The upstream thermopile 8, the downstream thermopile 5, the right thermopile 11, and the left thermopile 13
Is composed of a thermocouple. This thermocouple is p ++-
It is composed of Si and Al, has a cold junction and a hot junction, detects heat, and generates a temperature detection signal by generating a thermoelectromotive force from a temperature difference between the cold junction and the hot junction. ing.

As shown in FIG. 3, a diaphragm 3 is formed on the Si substrate 2, and a micro heater 4, an upstream thermopile 8,
Each hot junction of the downstream thermopile 5, the right thermopile 11, and the left thermopile 13 is formed.

According to the micro flow sensor 1 configured as described above, when the micro heater 4 starts heating by an external drive current, the heat generated from the micro heater 4 is converted into a downstream thermopile using gas as a medium. 5 and the upstream thermopile 8 are transmitted to the respective hot junctions. The cold junction of each thermopile is a Si substrate (S
i.sub. substrate), the temperature is the substrate temperature. Each hot junction is on the diaphragm, so it is heated by the transmitted heat, and its temperature rises above the Si 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 8 and the downstream thermopile 5 by thermal diffusion, and the first temperature detection signal from the upstream thermopile 8 and the second temperature detection signal from the downstream thermopile 5 Is 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 8 increases due to the flow velocity, and the difference signal between the second temperature detection signal and the first temperature detection signal becomes the flow velocity. It will be a corresponding positive value.

On the other hand, when the micro-heater 4 starts heating with an external driving current, the heat generated from the micro-heater 4 is supplied to the micro-heater 4 only by the heat diffusion effect of the gas without being affected by the gas flow velocity. Right thermopile 11 arranged substantially perpendicular to the gas flow direction
Is transmitted to Further, the left thermopile 1 disposed in a direction substantially perpendicular to the gas flow direction with respect to the micro heater 4.
Similar heat is transmitted to the third. Therefore, the third output terminals 12A and 12B are generated by the electromotive force of the right thermopile 11.
The fourth output terminals 14A, 1A are output by the right temperature detection signal output from the
Based on the left-side temperature detection signal output from 4B, it becomes possible to calculate the physical properties of the gas such as the heat diffusion constant determined by the heat conduction, heat diffusion, specific heat and the like.

Further, according to the micro flow sensor 1, since the micro heater 4, the upstream thermopile 8, the downstream thermopile 5, the right thermopile 11, and the left thermopile 13 are formed on the diaphragm 3, the heat capacity thereof is reduced. Thus, power consumption can be reduced. In addition, since the configuration of the micro flow sensor 1 is simple, there is an effect that it can be manufactured at low cost.

Next, a flow rate measuring process realized by the flow rate measuring device of FIG. 1 will be described with reference to a flowchart shown in FIG.

First, the micro heater 4 is heated by a driving current based on a pulse signal from the outside (step S1).
1), a second temperature detection signal is output from the downstream thermopile 5, and a first temperature detection signal is output from the upstream thermopile 8 (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. 5 shows a response of the first temperature detection signal and the second temperature detection signal to the pulse signal.

Next, the differential amplifier 33 receives the second temperature detection signal from the downstream thermopile 5 and the upstream thermopile 8
The difference signal from the first temperature detection signal is amplified (step S15).

Then, the adding section 45 adds the right temperature detection signal from the amplifier 35a and the left temperature detection signal from the amplifier 35b to obtain an addition signal (step S17).
FIG. 6 shows a timing chart of the right temperature detection signal, the left temperature detection signal, and the addition signal. Next, the division unit 47
Obtains a divided signal by dividing the amplified difference signal obtained in step S15 by the addition signal obtained in step S17 (step S19).

Subsequently, the flow rate calculation unit 41 determines in step S1
The accurate flow rate of the gas is calculated based on the division signal obtained in step 9 (step S21). Further, the fluid property value calculation unit 4
3 is the sum of the addition signal obtained in step S17 and step S17.
Based on the accurate flow rate of the gas calculated in step 21, the physical properties of the gas, such as the thermal conductivity, specific heat, viscosity, and density of the gas, are calculated (step S23).

As described above, the right thermopile 11 and the left thermopile 13 arranged in a 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, the thermal diffusion constant is obtained from the temperature difference between the right thermopile 11, the left thermopile 13, and the microheater 4. 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 8 and the second temperature detection signal output by the downstream thermopile 5, and these values are used to determine the magnitude of the thermal diffusion constant. It changes according to. Therefore,
In principle, the first temperature detection signal and the second temperature detection signal are
Alternatively, by dividing these differences by the thermal diffusion constant, an accurate flow rate can be calculated even for gases having different thermal diffusion constants, that is, for any kind of gas.

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 11 and the left thermopile 13 decreases accordingly. That is, the heat diffusion around the right thermopile 11 and the left thermopile 13 is increased by the 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 8 and the downstream thermopile 5, the heat diffusion increases due to the gas flow in the same manner as around the right thermopile 11 and the left thermopile 13 (decrease in the amount of heat transferred from the micro heater 4). When the gas flow rate increases, the downstream thermopile 5
And the temperature of the gas around the upstream thermopile 8 becomes smaller.

Therefore, the difference between the second temperature detection signal from the downstream thermopile 5 and the first temperature detection signal from the upstream thermopile 8, which should normally increase in proportion to the increase in the gas flow velocity, is obtained. If the signal becomes smaller due to the increase in heat diffusion and the flow rate of the gas becomes too large, the decrease due to the increase in heat diffusion exceeds the increase due to the increase in flow velocity, and the signal increases despite the increase in flow rate. 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 added value of the right temperature detection signal output by the right thermopile 11 and the left temperature detection signal output by the left thermopile 13 is considered to be "1". The ratio of the added value of the right temperature detection signal and the left temperature detection signal in the case of there is imitated as a coefficient representing the rate of change of the amount of moving heat, this coefficient,
An operation of multiplying a difference signal between the second temperature detection signal from the downstream thermopile 5 and the first temperature detection signal from the upstream thermopile 8 is performed.

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 heat diffusion change is eliminated. Calculation becomes possible, and an accurate and high-resolution flow rate can be obtained.

In the above-described embodiment, the amplified difference signal between the second temperature detection signal from the downstream thermopile 5 and the first temperature detection signal from the upstream thermopile 8 obtained from the differential amplifier 33 is calculated as follows. In the divider 47, the influence of the change in heat diffusion is eliminated by dividing the right-side temperature detection signal from the amplifier 35a and the left-side temperature detection signal from the amplifier 35b by an addition signal obtained by the addition unit 45. The flow rate can be calculated.

In the above-described embodiment, the dividing unit 4
7 is performed prior to the calculation of the flow rate by the flow rate calculation unit 41. This is because of the thermal diffusion that appears in the amplified difference signal between the second temperature detection signal and the first temperature detection signal. This is because, in order to eliminate the influence of the change, it is not necessary 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 fluid physical property calculating unit 43 calculates 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 precision. The accurate flow rate of the gas excluding the influence of the change in heat diffusion is calculated in advance by the flow rate calculation unit 41, and this is reflected in the calculation of the physical property value by the fluid property value calculation unit 43.

However, the fluid property value calculation unit 4
Depending on the type of the factor calculated in step 3, the physical property value is calculated in advance by the fluid property value calculating unit 43, and the second temperature detection signal from the downstream thermopile 5 from the differential amplifier 33 and from this. Based on the amplified difference signal from the first temperature detection signal from the upstream thermopile 8 and the amplified temperature difference signal, the accurate flow rate of the gas excluding the influence of the change in heat diffusion may be calculated later.

As described above, in the above-described flow rate measuring device, the right thermopile 11 and the left thermopile 13 are arranged in the direction substantially perpendicular to the gas flow direction with respect to the microheater 4, and the right temperature detection signal and the left temperature detection signal are output. Since it is configured to output the gas, it is possible to accurately calculate the physical properties 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 flow direction of the gas. Can be specified.

Since the flow rate of the gas calculated by the flow rate calculation section 41 is corrected based on the calculated physical properties of the gas, the type and composition of the gas change without any special measures. Even in this case, the flow rate can be accurately measured.

Next, with reference to a flow chart shown in FIG. 7, an explanation will be given on the flow sensor abnormality determination processing in the flow rate measuring device shown in FIG.

In FIG. 7, first, the determination section 48 determines whether or not the gas flow rate calculated in step 21 of FIG. 4 exceeds a predetermined increased flow rate threshold value (step S3).
1). As an example, if a gas flow rate of, for example, 20 cubic meters / hour is measured in a home equipped with a No. 6 gas meter having the configuration of the gas flow rate measuring device of FIG. 1, such a flow rate cannot occur. Therefore, each temperature sensor of the flow sensor 1, that is, each thermopile may be abnormal.

Therefore, if the answer to step S31 is YES, the microcomputer 40 controls the shutoff valve 53 to be closed to perform an increased flow rate cutoff for cutting off the gas flow path (step S32). Next, the determination unit 48 checks the level of the pressure detection signal from the pressure sensor 51 (Step S33),
It is determined whether the pressure in the gas flow path is lower than a predetermined level (step S34).

Here, the work of confirming whether or not the pressure has dropped is performed in order to distinguish whether the above-mentioned interruption of the increased flow rate is caused by "sensor failure" or "hose dropout or pipe cracking". Will be When a large amount of gas flows in the gas flow channel due to a hose drop or a pipe crack, the downstream of the flow measurement device is in a state similar to the open state, and the pressure in the gas flow channel decreases.

On the other hand, when an abnormality occurs in the flow sensor 1, a large flow rate may be calculated without lowering the pressure in the gas flow path. As an example, the division operation is performed by the division unit 47 based on the output of each thermopile of the flow sensor 1. For example, when the downstream thermopile 5 or the upstream thermopile 8 becomes abnormal, the value of the numerator in the division operation becomes large. If it is, or the right thermopile 1
1 or the left thermopile 13 becomes abnormal, and when the denominator in the division operation becomes small, the flow rate calculation unit 41
May calculate abnormally large flow rates. As described above, the cause of the increase in the numerator is that the electromotive force of the downstream thermopile 5 or the upstream thermopile 8 becomes abnormally large, and the cause of the decrease in the denominator is the right thermopile 11 or the left thermopile 1.
3 may be damaged by open or short, or its electromotive force may become abnormally small.

Therefore, if the answer to step S34 is YES, the judging section 48 judges that the increased flow rate interruption has occurred due to a hose coming off or a pipe crack, etc.
The alarm of the pressure drop interruption is displayed on the display unit 52 to notify the user, and is notified to the gas management center of the gas company via the notification unit 55 (step S35), and then the process is terminated.

On the other hand, if the answer to step S34 is no,
The determination unit 48 determines that the increased flow rate interruption is an abnormality of each of the temperature sensors of the flow sensor 1, that is, any of the thermopiles, and the microcomputer 40 displays an alarm of the flow sensor abnormality on the display unit 52 to notify the user. At the same time, a notification is sent to the gas management center of the gas company via the notification unit 55 (step S36), and then the process is terminated.

As described above, when the calculated gas flow rate exceeds the predetermined increase flow rate threshold value and there is no pressure drop, the determination unit 48 determines that one of the temperature sensors is abnormal. Since the determination is made, erroneous flow rate measurement due to sensor abnormality can be prevented.

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 determination unit 48 determines that the sensor is abnormal based on the increase in the flow rate that is equal to or more than the predetermined threshold value and the absence of the pressure drop. The configuration may be such that, when the flow rate is measured after the interruption of the increased flow rate, it is determined that one of the temperature sensors is abnormal.

FIG. 8 is a flowchart showing an abnormality determination process of the flow sensor according to another embodiment of the present invention.

In FIG. 8, first, the determining unit 48 determines whether or not the gas flow rate calculated in step 21 of FIG. 4 exceeds a predetermined increased flow rate threshold value (step S4).
1). If the answer to step S41 is yes, the microcomputer 4
In step S42, the control unit controls the shutoff valve 53 to be closed to perform an increased flow rate cutoff that shuts off the gas flow path (step S42). Next, after the interruption of the increased flow rate, the determination section 48
The flow rate calculated in step 1 is confirmed (step S43), and then the determination unit 48 determines whether the flow rate calculated by the flow rate calculation unit 41 is zero.

Here, in the case where a large amount of gas flows in the gas flow path and the increased flow rate is cut off,
Is closed, the flow rate calculated by the flow rate calculation unit 41 becomes zero. On the other hand, when the increased flow rate interruption is performed due to “sensor abnormality”, the flow rate calculation unit 4
The flow rate calculated in 1 does not become zero but remains at a flow rate value exceeding a predetermined threshold value.

Therefore, if the answer to step S44 is YES, the judging unit 48 judges that the large flow of gas has actually flowed in the gas flow passage and the increased flow rate has been interrupted.
In the case of 0, the alarm of cutoff of the increased flow rate is displayed on the display unit 52 to notify the user, and the alarm is notified to the gas management center of the gas company via the notification unit 55 (step S35), and then the process is terminated.

On the other hand, if the answer to step S44 is no,
The determination unit 48 determines that the increased flow rate interruption is an abnormality of each of the temperature sensors of the flow sensor 1, that is, any of the thermopiles, and the microcomputer 40 displays an alarm of the flow sensor abnormality on the display unit 52 to notify the user. At the same time, a notification is sent to the gas management center of the gas company via the notification unit 55 (step S36), and then the process is terminated.

As described above, when the flow rate is measured after the interruption of the increased flow rate, the determination section 48 determines that one of the temperature sensors is abnormal, so that the erroneous flow rate measurement due to the sensor abnormality is prevented. it can.

[0074]

According to the first aspect of the present invention, it is possible to determine whether the flow sensor is abnormal, and to prevent erroneous flow rate measurement due to the sensor abnormality.

According to the second aspect of the present invention, the abnormality of the flow sensor can be determined, the erroneous measurement of the flow rate due to the sensor abnormality can be prevented, and the sensor abnormality can be notified to the user or the gas company. Can be operated.

According to the third aspect of the present invention, it is possible to determine the abnormality of the flow sensor, prevent erroneous measurement of the flow rate due to the sensor abnormality, and operate the apparatus on the safe side.

According to the fourth aspect of the present invention, it is possible to determine the abnormality of the flow sensor, and it is possible to prevent erroneous flow rate measurement due to the sensor abnormality.

According to the fifth aspect of the present invention, it is possible to judge the abnormality of the flow sensor, prevent erroneous measurement of the flow rate due to the sensor abnormality, and inform the user or the gas company of the sensor abnormality, thereby making the apparatus safer. Can be operated.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing an embodiment of a flow rate measuring device using a flow sensor according to the present invention.

FIG. 2 is a configuration diagram of a micro flow sensor used in the flow measurement device of FIG.

FIG. 3 is a cross-sectional view of a micro flow sensor used in the flow measuring device of FIG.

FIG. 4 is a flowchart showing a flow rate measuring process realized by the flow rate measuring device of FIG. 1;

FIG. 5 is a diagram showing a first temperature detection signal and a second temperature detection signal.

FIG. 6 is a diagram illustrating a right temperature detection signal and a left temperature detection signal.

FIG. 7 is a flowchart illustrating an abnormality determination process of a flow sensor in the flow rate measurement device of FIG. 1;

FIG. 8 is a flowchart illustrating an abnormality determination process of a flow sensor according to another embodiment of the present invention.

FIG. 9 is a configuration block diagram of an example of a flow measurement device using a conventional flow sensor.

FIG. 10 is a flowchart showing a flow rate measuring process realized by the flow rate measuring device of FIG. 9;

[Explanation of symbols]

 Reference Signs List 1 micro flow sensor (flow sensor) 2 Si substrate (support substrate) 4 micro heater (heater) 5 downstream thermopile (downstream temperature sensor) 8 upstream thermopile (upstream temperature sensor) 11 right thermopile (right temperature sensor) 13 Left thermopile (left temperature sensor) 48 Judgment unit (judgment unit) 52 Display unit (part of alarm unit) 54 Shutoff valve (cutoff unit) 55 Notification unit (part of alarm unit)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F030 CA10 CB04 CC13 CE02 CE27 CF05 CF11 CF20 2F035 EA02 EA05 EA08 EA09

Claims (5)

[Claims] 1. A heater for heating a gas flowing through a gas flow path, an upstream temperature sensor disposed on an upstream side of the gas with respect to the heater, and a downstream disposed on a downstream side of the gas with respect to the heater. A right-side temperature sensor, a right-side temperature sensor disposed in a direction substantially perpendicular to the gas flow direction with respect to the heater, and a side of the gas that is opposed to the right-side temperature sensor across the heater. A flow sensor comprising: a left temperature sensor disposed in a direction substantially perpendicular to the flow direction; and a support substrate that supports the heater, the upstream temperature sensor, the downstream temperature sensor, the right temperature sensor, and the left temperature sensor. In the flow rate measuring device that calculates the gas flow rate based on the output of each of the temperature sensors when the heater is turned on, the calculated gas flow rate exceeds a predetermined threshold, One case without the pressure drop of the gas flow path, the flow rate measuring device using a flow sensor comprising the abnormality determination means any of the sensors in each of the temperature sensors. 2. A flow rate measuring apparatus using a flow sensor according to claim 1, further comprising an alarming means for alarming the sensor abnormality when said judging means judges that the sensor is abnormal. 3. The flow rate measuring device using a flow sensor according to claim 1, further comprising a shutoff unit that shuts off the gas flow path when the determination unit determines that the sensor is abnormal. 4. A heater for heating a gas flowing through a gas flow path, an upstream temperature sensor disposed upstream of the gas with respect to the heater, and a downstream sensor disposed downstream of the gas with respect to the heater. A right-side temperature sensor, a right-side temperature sensor disposed in a direction substantially perpendicular to the gas flow direction with respect to the heater, and a side of the gas that is opposed to the right-side temperature sensor across the heater. A flow sensor comprising: a left temperature sensor disposed in a direction substantially orthogonal to the flow direction; and a support substrate that supports the heater, the upstream temperature sensor, the downstream temperature sensor, the right temperature sensor, and the left temperature sensor. A flow rate measuring device that calculates a gas flow rate based on an output of each of the temperature sensors when the heater is turned on, wherein the calculated gas flow rate exceeds a predetermined threshold value. In this case, there is provided a shutoff unit for shutting off the gas flow path, and a judging unit for judging that one of the temperature sensors is abnormal when the flow rate is measured to be present after the shutoff by the shutoff unit. A flow rate measuring device using a flow sensor. 5. The flow rate measuring device using a flow sensor according to claim 4, further comprising an alarm unit for alarming the sensor abnormality when the judgment unit judges that the sensor is abnormal.