JP6434238B2

JP6434238B2 - Flow meter and correction value calculation method

Info

Publication number: JP6434238B2
Application number: JP2014140721A
Authority: JP
Inventors: 久夫清田
Original assignee: Azbil Corp
Current assignee: Azbil Corp
Priority date: 2014-07-08
Filing date: 2014-07-08
Publication date: 2018-12-05
Anticipated expiration: 2034-07-08
Also published as: JP2016017844A

Description

本発明は、流量計および補正値算出方法に関する。 The present invention relates to a flow meter and a correction value calculation method.

従来、ガスや空気等の流体の温度を計測する流量計として、抵抗Ｒ１１、Ｒ１２、ヒータＲｈおよび周囲温度センサＲｒからなるブリッジ回路が平衡状態となるように供給電位を制御し、所定の温度分布が得られるようにヒータＲｈを駆動するヒータ駆動手段１１Ｂと、供給電位Ｖ１とブリッジ回路の出力電位Ｖ２とに基づき、シリコンチップなどの基材からなる基台５０の表面に埋め込まれた周囲温度センサＲｒの温度を流体の温度として算出する流体温度算出手段１４Ｂと、を備える流量計が知られていた（特許文献１）。 Conventionally, as a flow meter for measuring the temperature of a fluid such as gas or air, a supply potential is controlled so that a bridge circuit including resistors R11 and R12, a heater Rh, and an ambient temperature sensor Rr is in an equilibrium state, and a predetermined temperature distribution is obtained. The ambient temperature sensor embedded in the surface of the base 50 made of a base material such as a silicon chip based on the heater driving means 11B for driving the heater Rh and the supply potential V1 and the output potential V2 of the bridge circuit so as to obtain There has been known a flow meter including fluid temperature calculation means 14B that calculates the temperature of Rr as the temperature of the fluid (Patent Document 1).

また、上述したような流量計は、周囲温度センサで計測された流体の温度より一定温度だけ高くなるようにヒータで被測定流体を加熱し、所定の温度分布を発生させ、その温度分布から被測定流体の流速を算出し、その流速に基づいて流体流量を計測することが知られていた（特許文献２）。 In addition, the flow meter as described above heats the fluid to be measured with a heater so that the fluid temperature is higher than the temperature of the fluid measured by the ambient temperature sensor, generates a predetermined temperature distribution, and the temperature distribution is obtained from the temperature distribution. It has been known that the flow rate of the measurement fluid is calculated and the fluid flow rate is measured based on the flow rate (Patent Document 2).

特開２００４−１１７１５９号公報JP 2004-117159 A 特開２００４−１１７１５７号公報JP 2004-117157 A

しかしながら、上述したような流量計においては、周囲温度センサは基台の表面に埋め込まれているため、周囲温度センサの温度を、被測定流体の温度として算出するよりも、基台の温度として算出するおそれがあり、被測定流体の正確な温度を算出することができないおそれがあった。このように、被測定流体の正確な温度を算出することができない結果、被測定流体の流量を正確に計測することができないおそれがあった。 However, since the ambient temperature sensor is embedded in the surface of the base in the flow meter as described above, the temperature of the ambient temperature sensor is calculated as the temperature of the base rather than as the temperature of the fluid to be measured. There is a risk that the accurate temperature of the fluid to be measured cannot be calculated. As described above, the accurate temperature of the fluid to be measured cannot be calculated. As a result, the flow rate of the fluid to be measured may not be accurately measured.

そこで、本発明は、被測定流体の流量を正確に計測することを目的の一つとし得る。 Therefore, the present invention can be one of the objects to accurately measure the flow rate of the fluid to be measured.

上記課題を解決するために、本発明の一側面に係る流量計は、被測定流体の流量を計測する流れセンサと、計測された前記流量を補正するための補正値を算出する補正値算出部と、を備え、前記流れセンサは、基板と、前記被測定流体の温度に強く影響を受けるように配置された第１抵抗体と、前記基板の温度に強く影響を受けるように配置された第２抵抗体と、を備え、前記流れセンサは、前記第１抵抗体を含む周囲温度センサで計測される温度よりも一定温度高くなるように制御されるヒータで加えられた熱が前記被測定流体の流れ下流方向に運ばれる運搬効果によって、前記ヒータより前記被測定流体の流れ上流側に設けられた上流側測温抵抗素子の温度よりも、前記ヒータより前記被測定流体の流れ下流側に設けられた下流側測温抵抗素子の温度が高くなった場合における、前記上流側測温抵抗素子の電気抵抗と前記下流側測温抵抗素子の電気抵抗との間の差に基づいて被測定流体の流量を計測し、前記補正値算出部は、前記第１抵抗体の抵抗値と前記第２抵抗体の抵抗値との差の変化量に対応づけられる、前記流量を補正するための補正値を算出する。 In order to solve the above problem, a flow meter according to one aspect of the present invention includes a flow sensor that measures the flow rate of a fluid to be measured, and a correction value calculation unit that calculates a correction value for correcting the measured flow rate. And the flow sensor is disposed so as to be strongly influenced by the temperature of the substrate, a first resistor disposed so as to be strongly influenced by the temperature of the fluid to be measured. And the flow sensor receives heat applied by a heater that is controlled to be a certain temperature higher than a temperature measured by an ambient temperature sensor including the first resistor. Is provided downstream of the flow of the fluid under measurement from the heater than the temperature of the upstream resistance temperature element provided upstream of the flow of the fluid under measurement from the heater. The downstream temperature measuring resistor When the temperature of the element becomes high, and measures the flow rate of the fluid to be measured based on the difference between the electrical resistance of the electrical resistance of the upstream-side temperature measuring resistance element downstream temperature measuring resistive element, the correction The value calculation unit calculates a correction value for correcting the flow rate, which is associated with a change amount of a difference between the resistance value of the first resistor and the resistance value of the second resistor.

上記課題を解決するために、本発明の一側面に係る補正値算出方法は、流れセンサにより被測定流体の流量を計測する工程と、計測された前記流量を補正するための補正値を算出する工程と、を含み、前記流れセンサは、基板と、前記被測定流体の温度に強く影響を受けるように配置された第１抵抗体と、前記基板の温度に強く影響を受けるように配置された第２抵抗体と、を備え、前記流量を計測する工程は、前記第１抵抗体を含む周囲温度センサで計測される温度よりも一定温度高くなるように制御されるヒータで加えられた熱が前記被測定流体の流れ下流方向に運ばれる運搬効果によって、前記ヒータより前記被測定流体の流れ上流側に設けられた上流側測温抵抗素子の温度よりも、前記ヒータより前記被測定流体の流れ下流側に設けられた下流側測温抵抗素子の温度が高くなった場合における、前記上流側測温抵抗素子の電気抵抗と前記下流側測温抵抗素子の電気抵抗との間の差に基づいて被測定流体の流量を計測する工程を含み、前記補正値を算出する工程は、前記第１抵抗体の抵抗値と前記第２抵抗体の抵抗値との差の変化量に対応づけられる、前記流量を補正するための補正値を算出する工程を含む。 In order to solve the above-described problem, a correction value calculation method according to one aspect of the present invention calculates a flow rate of a fluid to be measured by a flow sensor and calculates a correction value for correcting the measured flow rate. The flow sensor is arranged to be strongly influenced by the temperature of the substrate, the first resistor arranged to be strongly influenced by the temperature of the fluid to be measured, and the substrate. A step of measuring the flow rate, wherein the heat applied by the heater controlled to be a constant temperature higher than the temperature measured by the ambient temperature sensor including the first resistor. The flow of the fluid to be measured from the heater is higher than the temperature of the upstream resistance temperature element provided on the upstream side of the flow of the fluid to be measured from the heater due to the transport effect that is conveyed in the downstream direction of the flow of the fluid to be measured. Provided on the downstream side When the temperature of the measured resistance element on the downstream side becomes high, based on the difference between the electric resistance of the upstream resistance element and the electrical resistance of the downstream resistance element, the fluid to be measured The step of calculating the correction value includes a step of measuring a flow rate, and the step of calculating the correction value corrects the flow rate associated with a change amount of a difference between a resistance value of the first resistor and a resistance value of the second resistor. Calculating a correction value for this.

本発明によれば、基板と、上記基板上に配置され、上記基板から熱絶縁された第１抵抗体と、を備える流れセンサにより計測された被測定流体の流量を、補正値算出部により上記第１抵抗体の抵抗値の変化量に対応づけられる、上記流量を補正するための補正値を算出することにより、当該補正値に基づいて被測定流体の流量を補正することができ、被測定流体の流量を正確に計測することにつなげることができる。 According to the present invention, the flow rate of the fluid to be measured measured by the flow sensor including the substrate and the first resistor disposed on the substrate and thermally insulated from the substrate is calculated by the correction value calculation unit. By calculating a correction value for correcting the flow rate, which is associated with the amount of change in the resistance value of the first resistor, the flow rate of the fluid to be measured can be corrected based on the correction value. This can lead to accurate measurement of the fluid flow rate.

本発明の第１実施形態に係る流量計の構成を示す構成図である。It is a block diagram which shows the structure of the flowmeter which concerns on 1st Embodiment of this invention. 本発明の第１実施形態に係る流量計の熱式流れセンサの構成を説明するための斜視図である。It is a perspective view for demonstrating the structure of the thermal type flow sensor of the flowmeter which concerns on 1st Embodiment of this invention. 図２に示すI−I線に沿った断面図である。It is sectional drawing along the II line shown in FIG. 本発明の第１実施形態に係る２つの周囲温度測温抵抗素子の出力電圧（抵抗値の差）と温度差との関係を示すグラフである。It is a graph which shows the relationship between the output voltage (difference of resistance value) and temperature difference of two ambient temperature measuring resistance elements which concern on 1st Embodiment of this invention. 本発明の第１実施形態に係る流量計の回路構成例である。It is a circuit structural example of the flowmeter which concerns on 1st Embodiment of this invention. 本発明の第１実施形態に係る流量計の流量補正機能を説明するためのフローチャートである。It is a flowchart for demonstrating the flow volume correction function of the flowmeter which concerns on 1st Embodiment of this invention. 本発明の第２実施形態に係る流量計の熱式流れセンサの構成を説明するための斜視図である。It is a perspective view for demonstrating the structure of the thermal type flow sensor of the flowmeter which concerns on 2nd Embodiment of this invention. 図７に示すI−I線に沿った断面図である。It is sectional drawing along the II line shown in FIG. 本発明の第２実施形態に係る流量計の回路構成例である。It is a circuit structural example of the flowmeter which concerns on 2nd Embodiment of this invention.

以下、図面を参照して本発明の実施の形態を説明する。以下の図面の記載において、同一又は類似の部分には同一又は類似の符号を付して表している。図面は模式的なものであり、必ずしも実際の寸法や比率等とは一致しない。図面相互間においても互いの寸法の関係や比率が異なる部分が含まれていることがある。 Embodiments of the present invention will be described below with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are schematic and do not necessarily match actual dimensions and ratios. In some cases, the dimensional relationships and ratios may be different between the drawings.

＜第１実施形態＞
図１〜図６を用いて、本発明の第１実施形態に係る流量計１（第１実施形態においては１Ａ）について説明する。図１は、本発明の第１実施形態に係る流量計１Ａの構成を示す構成図である。図１に示すように、本実施形態に係る流量計１Ａは、例示的に、ガスなどの被測定流体が流通する図示していない配管の一部に取り付けられる流路保持体２と、流路保持体２に一体的に接続される計測ユニット３と、を備えて構成されている。 <First Embodiment>
A flow meter 1 (1A in the first embodiment) according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram showing a configuration of a flow meter 1A according to the first embodiment of the present invention. As shown in FIG. 1, a flow meter 1A according to the present embodiment exemplarily includes a flow path holding body 2 attached to a part of a pipe (not shown) through which a fluid to be measured such as gas flows, and a flow path And a measurement unit 3 integrally connected to the holding body 2.

流路保持体２の内部には、被測定流体が矢印の方向に流通する流路２ａが形成されている。計測ユニット３は、流路２ａ内を流通する被測定流体の流量を計測するものである。なお、図１は、流路保持体２の断面図と、計測ユニット３の機能的構成を説明するためのブロック図と、を複合的に示した構成図である。 Inside the flow path holder 2, a flow path 2a through which the fluid to be measured flows in the direction of the arrow is formed. The measuring unit 3 measures the flow rate of the fluid to be measured flowing through the flow path 2a. FIG. 1 is a configuration diagram in which a cross-sectional view of the flow path holding body 2 and a block diagram for explaining a functional configuration of the measurement unit 3 are combined.

流路保持体２には、上流側の端部に流入口４が、下流側の端部に流出口５が、各々設けられており、流路２ａは、流入口４及び流出口５の各々に取り付けられる図示していない配管と連通している。また、流路２ａの内壁には、流路２ａ内を流通する被測定流体の流量を計測するための熱式流れセンサ１０が設置されている。 The flow path holding body 2 is provided with an inflow port 4 at an upstream end and an outflow port 5 at a downstream end, and the flow path 2a includes the inflow port 4 and the outflow port 5, respectively. It communicates with a pipe (not shown) attached to the pipe. A thermal flow sensor 10 for measuring the flow rate of the fluid to be measured flowing through the flow path 2a is installed on the inner wall of the flow path 2a.

図２は、図１に示す流量計１Ａの熱式流れセンサ１０（第１実施形態においては１０Ａ）の構成を説明するための斜視図である。また、図３は、図２に示すI−I線に沿った断面図である。図２及び図３に示すように、熱式流れセンサ１０Ａは、例示的に、キャビティ１２及びキャビティ１９が設けられた基板１１と、基板１１上にキャビティ１２及びキャビティ１９を覆うように配置された絶縁膜１３と、絶縁膜１３に設けられたヒータ１４と、ヒータ１４より上流側に設けられた上流側測温抵抗素子１５と、ヒータ１４より下流側に設けられた下流側測温抵抗素子１６と、上流側測温抵抗素子１５より上流側に設けられた周囲温度測温抵抗素子１７及び周囲温度測温抵抗素子１８（第１抵抗体）と、ヒータ１４より下流側に設けられた周囲温度測温抵抗素子１００と、を備えて構成されている。 FIG. 2 is a perspective view for explaining the configuration of the thermal flow sensor 10 (10A in the first embodiment) of the flow meter 1A shown in FIG. 3 is a cross-sectional view taken along the line II shown in FIG. As shown in FIGS. 2 and 3, the thermal flow sensor 10 </ b> A is illustratively disposed on the substrate 11 provided with the cavity 12 and the cavity 19, and on the substrate 11 so as to cover the cavity 12 and the cavity 19. Insulating film 13, heater 14 provided on insulating film 13, upstream temperature measuring resistor element 15 provided upstream of heater 14, and downstream temperature measuring resistor element 16 provided downstream of heater 14 The ambient temperature resistance element 17 and the ambient temperature resistance element 18 (first resistor) provided on the upstream side of the upstream temperature resistance element 15, and the ambient temperature provided on the downstream side of the heater 14. And a resistance thermometer element 100.

絶縁膜１３のうち、キャビティ１２を覆う部分は、断熱性の第１ダイヤフラムを構成している。また、絶縁膜１３のうち、キャビティ１９を覆う部分は、断熱性の第２ダイヤフラムを構成している。ここで、ヒータ１４、上流側測温抵抗素子１５、および下流側測温抵抗素子１６は、第１ダイヤフラムに設けられている。このように、ヒータ１４、上流側測温抵抗素子１５、および下流側測温抵抗素子１６は、基板１１から熱的に遮断（熱絶縁）されている。また、周囲温度測温抵抗素子１８（第１抵抗体）は、第２ダイヤフラムに設けられている。このように、周囲温度測温抵抗素子１８（第１抵抗体）は、基板１１から熱的に遮断（熱絶縁）されている。また、図２に示すように、周囲温度測温抵抗素子１８（第１抵抗体）は、ヒータ１４と同一基板１１上に設けられながらも、ヒータ１４から出来るだけ離し、且つ、被測定流体の流れ上流側に配置するとよい。さらに、上述したとおり、周囲温度測温抵抗素子１８（第１抵抗体）は、ヒータ１４が設けられるダイヤフラム（第１ダイヤフラム）とは異なるダイヤフラム（第２ダイヤフラム）に設けられる。このような構成を採用するのは、ヒータ１４の周辺はヒータ１４により加熱されており、周囲温度測温抵抗素子１８がヒータ１４の近くに設置され、周囲温度測温抵抗素子１８が、ヒータ１４が設けられるダイヤフラムと同一のダイヤフラムに設けられ、又は、周囲温度測温抵抗素子１８が被測定流体の流れ下流側に配置されると、周囲温度測温抵抗素子１８（第１抵抗体）を含む周囲温度センサ（不図示）の被測定流体の温度測定に誤差が生じるおそれがある。このような被測定流体の温度測定の誤差を防ぐためである。 A portion of the insulating film 13 covering the cavity 12 constitutes a heat insulating first diaphragm. Moreover, the part which covers the cavity 19 among the insulating films 13 comprises the 2nd heat-insulating diaphragm. Here, the heater 14, the upstream temperature measuring resistance element 15, and the downstream temperature measuring resistance element 16 are provided in the first diaphragm. As described above, the heater 14, the upstream temperature measuring resistance element 15, and the downstream temperature measuring resistance element 16 are thermally insulated (thermally insulated) from the substrate 11. In addition, the ambient temperature measuring resistance element 18 (first resistor) is provided in the second diaphragm. As described above, the ambient temperature measuring resistance element 18 (first resistor) is thermally insulated (thermally insulated) from the substrate 11. As shown in FIG. 2, the ambient temperature measuring resistance element 18 (first resistor) is provided on the same substrate 11 as the heater 14, but is separated from the heater 14 as much as possible, and the fluid to be measured is It may be arranged on the upstream side of the flow. Further, as described above, the ambient temperature measuring resistance element 18 (first resistor) is provided on a diaphragm (second diaphragm) different from the diaphragm (first diaphragm) on which the heater 14 is provided. Such a configuration is adopted because the heater 14 is heated around the heater 14, the ambient temperature measuring resistance element 18 is installed near the heater 14, and the ambient temperature measuring resistance element 18 is connected to the heater 14. If the ambient temperature measuring resistance element 18 is arranged on the downstream side of the flow of the fluid to be measured, the ambient temperature measuring resistance element 18 (first resistor) is included. An error may occur in the temperature measurement of the fluid to be measured by an ambient temperature sensor (not shown). This is to prevent such an error in temperature measurement of the fluid to be measured.

基板１１に設けられている周囲温度測温抵抗素子１７を含む周囲温度センサ（不図示）は、周囲温度を計測する。また、基板１１に設けられている周囲温度測温抵抗素子１００を含む周囲温度センサ（不図示）は、周囲温度を計測する。ヒータ１４は、キャビティ１２を覆う絶縁膜１３の略中心に配置されており、流路２ａを流通する被測定流体を、周囲温度センサが計測した温度よりも一定温度高くなるように加熱する。上流側測温抵抗素子１５はヒータ１４より上流側の温度を検出するために用いられ、下流側測温抵抗素子１６はヒータ１４より下流側の温度を検出するために用いられる。 An ambient temperature sensor (not shown) including the ambient temperature resistance element 17 provided on the substrate 11 measures the ambient temperature. An ambient temperature sensor (not shown) including the ambient temperature measuring resistance element 100 provided on the substrate 11 measures the ambient temperature. The heater 14 is disposed substantially at the center of the insulating film 13 covering the cavity 12, and heats the fluid to be measured flowing through the flow path 2a so as to be higher than the temperature measured by the ambient temperature sensor. The upstream resistance temperature sensor 15 is used to detect the temperature upstream of the heater 14, and the downstream temperature resistance element 16 is used to detect the temperature downstream of the heater 14.

ここで、流路２ａ内における被測定流体の流量が零の場合、ヒータ１４で加えられた熱は、上流方向と下流方向へ対称的に拡散する。従って、上流側測温抵抗素子１５の温度と下流側測温抵抗素子１６との温度は等しくなり、上流側測温抵抗素子１５の電気抵抗と下流側測温抵抗素子１６の電気抵抗とは等しくなる。これに対し、流路２ａ内における被測定流体が上流側から下流側へと流通している場合、ヒータ１４で加えられた熱は下流方向に運ばれる（運搬効果）。 Here, when the flow rate of the fluid to be measured in the flow path 2a is zero, the heat applied by the heater 14 is diffused symmetrically in the upstream direction and the downstream direction. Accordingly, the temperature of the upstream resistance thermometer element 15 and the temperature of the downstream resistance thermometer element 16 are equal, and the electrical resistance of the upstream resistance thermometer element 15 and the electrical resistance of the downstream resistance thermometer element 16 are equal. Become. On the other hand, when the fluid to be measured in the flow path 2a flows from the upstream side to the downstream side, the heat applied by the heater 14 is conveyed in the downstream direction (transport effect).

従って、上流側測温抵抗素子１５の温度よりも下流側測温抵抗素子１６の温度が高くなり、上流側測温抵抗素子１５の電気抵抗と下流側測温抵抗素子１６の電気抵抗との間に差が生じる。この電気抵抗の差は、流路２ａ内を流通する被測定流体の速度や流量と相関関係があることが知られている。このため、上流側測温抵抗素子１５の電気抵抗と下流側測温抵抗素子１６の電気抵抗との差に基づいて、流路２ａ内を流通する被測定流体の速度や流量を算出（計測）することができる。 Accordingly, the temperature of the downstream resistance element 16 becomes higher than the temperature of the upstream resistance element 15, and between the electrical resistance of the upstream resistance element 15 and the electrical resistance of the downstream resistance element 16. There will be a difference. This difference in electrical resistance is known to correlate with the speed and flow rate of the fluid to be measured flowing through the flow path 2a. For this reason, the speed and flow rate of the fluid to be measured flowing in the flow path 2a are calculated (measured) based on the difference between the electrical resistance of the upstream resistance thermometer element 15 and the electrical resistance of the downstream resistance thermometer element 16. can do.

なお、基板１１の材料としては、シリコン(Ｓｉ)等が使用可能である。絶縁膜１３の材料としては、酸化ケイ素(ＳｉＯ₂)、シリコンナイトライド（Ｓｉ₃Ｎ₄）等が使用可能である。キャビティ１２は、異方性エッチング等により形成される。また、ヒータ１４、上流側測温抵抗素子１５、下流側測温抵抗素子１６、周囲温度測温抵抗素子１７及び周囲温度測温抵抗素子１８の各々の材料としては、白金(Ｐｔ)等が使用可能であり、これらは、リソグラフィ法等により形成可能である。 As the material of the substrate 11, silicon (Si) or the like can be used. As a material of the insulating film 13, silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), or the like can be used. The cavity 12 is formed by anisotropic etching or the like. Further, platinum (Pt) or the like is used as the material of each of the heater 14, the upstream side resistance temperature sensor 15, the downstream side resistance temperature sensor 16, the ambient temperature resistance element 17, and the ambient temperature resistance element 18. These can be formed by a lithography method or the like.

図１に戻り、計測ユニット３は、例示的に、熱式流れセンサ１０Ａに電気的に接続された中央演算装置２０と、中央演算装置２０に電気的に接続された記憶装置３０及び表示装置４０と、を備えて構成されている。 Returning to FIG. 1, the measurement unit 3 exemplarily includes a central processing unit 20 electrically connected to the thermal flow sensor 10 </ b> A, and a storage device 30 and a display device 40 electrically connected to the central processing unit 20. And is configured.

記憶装置３０は、例えばＤＲＡＭ等の揮発性メモリから構成することができる。記憶装置３０には、各種制御プログラムに加えて、熱式流れセンサ１０Ａのセンサ出力に基づいて被測定流体の流量を算出するための情報（演算式、テーブル等）や、後述する、算出された被測定流体の流量を補正するための情報、即ち、周囲温度測温抵抗素子１８（第１抵抗体）の抵抗値の変化量と、算出された被測定流体の流量を補正するための補正値と、の相関関係を示す関係式又はテーブルなどが記憶されている。 The storage device 30 can be composed of a volatile memory such as a DRAM, for example. In the storage device 30, in addition to various control programs, information (calculation formula, table, etc.) for calculating the flow rate of the fluid to be measured based on the sensor output of the thermal flow sensor 10A, calculated later, and calculated Information for correcting the flow rate of the fluid to be measured, that is, the amount of change in the resistance value of the ambient temperature resistance element 18 (first resistor) and the correction value for correcting the calculated flow rate of the fluid to be measured And a relational expression or a table indicating the correlation.

表示装置４０は、例えば液晶ディスプレイ等の画像表示部と、入力キー等を有して各種設定や情報入力が可能な操作部と、などを備えて構成される。 The display device 40 includes, for example, an image display unit such as a liquid crystal display, an operation unit that has input keys and the like and can perform various settings and information input.

中央演算装置２０は、例えばＣＰＵ等から構成されており、記憶装置３０に記憶された各種情報や各種制御プログラムを読み込み、各種演算処理を実行して流量計１Ａの各種機器を統合制御する。本実施形態における中央演算装置２０は、熱式流れセンサ１０Ａを用いて算出した被測定流体の流量を、後述する補正値に基づいて補正する装置であり、機能的に、流量計測部２２、補正値算出部２４、及び流量補正部２６を備えて構成されている。 The central processing unit 20 includes, for example, a CPU and the like, reads various information and various control programs stored in the storage device 30, executes various arithmetic processes, and integrally controls various devices of the flow meter 1A. The central processing unit 20 in the present embodiment is a device that corrects the flow rate of the fluid to be measured calculated using the thermal flow sensor 10A based on a correction value to be described later. A value calculation unit 24 and a flow rate correction unit 26 are provided.

ここで、熱式流れセンサ１０Ａは、上述したとおり、周囲温度測温抵抗素子１７及び周囲温度測温抵抗素子１８（第１抵抗体）を備えている。そして、周囲温度測温抵抗素子１７は、基板１１上に設けられており、周囲温度測温抵抗素子１８は、第２ダイヤフラムに設けられている。本願発明者は、周囲温度測温抵抗素子１７を含む周囲温度センサは、基板１１の温度に強く影響を受け、基板１１の温度を計測し、周囲温度測温抵抗素子１８を含む周囲温度センサは、被測定流体の温度に強く影響を受け、被測定流体の温度を計測することを見出した。これは、周囲温度測温抵抗素子１７は、基板１１に設けられている一方で、周囲温度測温抵抗素子１８は、第２ダイヤフラムに設けられているため、基板１１から熱絶縁され、そして、第２ダイヤフラム下に位置するキャビティ１９内では被測定流体が流通していることによって、より被測定流体の温度の影響を受け易いためである。 Here, as described above, the thermal flow sensor 10A includes the ambient temperature measurement resistance element 17 and the ambient temperature resistance measurement element 18 (first resistor). The ambient temperature measuring resistance element 17 is provided on the substrate 11, and the ambient temperature measuring resistance element 18 is provided on the second diaphragm. The inventor of the present application is that the ambient temperature sensor including the ambient temperature measurement resistance element 17 is strongly influenced by the temperature of the substrate 11, measures the temperature of the substrate 11, and the ambient temperature sensor including the ambient temperature measurement resistance element 18 is It was found that the temperature of the fluid to be measured was measured by being strongly influenced by the temperature of the fluid to be measured. This is because the ambient temperature measuring resistance element 17 is provided on the substrate 11, while the ambient temperature resistance measuring element 18 is provided on the second diaphragm, so that it is thermally insulated from the substrate 11, and This is because the fluid to be measured circulates in the cavity 19 located below the second diaphragm, so that it is more susceptible to the temperature of the fluid to be measured.

また、例えば、被測定流体の温度が一定である場合において、抵抗素子の抵抗値は一定であるため、周囲温度測温抵抗素子１７の抵抗値と、周囲温度測温抵抗素子１８の抵抗値と、の差は一定であり、周囲温度測温抵抗素子１７を含む周囲温度センサと、周囲温度測温抵抗素子１８を含む周囲温度センサと、が算出する温度の差も一定である。しかしながら、被測定流体の温度が変化した場合、当該被測定流体の温度の変化に対応して、周囲温度測温抵抗素子１７及び周囲温度測温抵抗素子１８の抵抗値の差（出力電圧）は変動する。また、被測定流体の温度が変化した場合、当該被測定流体の温度の変化に対応して、周囲温度測温抵抗素子１７を含む周囲温度センサと、周囲温度測温抵抗素子１８を含む周囲温度センサと、が算出する温度の差も変動する。具体的には、被測定流体の温度が変化した場合、周囲温度測温抵抗素子１８の抵抗値は変化する。一方で、周囲温度測温抵抗素子１７の抵抗値は、被測定流体の温度の変化に関わらず、一定である。また、被測定流体の温度が変化した場合、周囲温度測温抵抗素子１８を含む周囲温度センサは、被測定流体の変化後の温度を計測する。一方で、周囲温度測温抵抗素子１７を含む周囲温度センサは、被測定流体の温度の変化に関わらず、基板１１の温度を計測するため、計測温度は一定である。よって、被測定流体の温度の変化前後で、周囲温度測温抵抗素子１７及び周囲温度測温抵抗素子１８の抵抗値の差（出力電圧）も変動し、周囲温度測温抵抗素子１８を含む周囲温度センサと周囲温度測温抵抗素子１７を含む周囲温度センサとが算出する温度の差も変動する。 For example, when the temperature of the fluid to be measured is constant, the resistance value of the resistance element is constant. Therefore, the resistance value of the ambient temperature measurement resistance element 17 and the resistance value of the ambient temperature measurement resistance element 18 are The temperature difference calculated by the ambient temperature sensor including the ambient temperature measuring resistance element 17 and the ambient temperature sensor including the ambient temperature resistance measuring element 18 is also constant. However, when the temperature of the fluid to be measured changes, the difference (output voltage) between the resistance values of the ambient temperature resistance element 17 and the ambient temperature resistance element 18 corresponds to the change in the temperature of the fluid to be measured. fluctuate. In addition, when the temperature of the fluid to be measured changes, the ambient temperature sensor including the ambient temperature resistance element 17 and the ambient temperature including the ambient temperature resistance element 18 corresponding to the temperature change of the fluid to be measured. The temperature difference calculated by the sensor also varies. Specifically, when the temperature of the fluid to be measured changes, the resistance value of the ambient temperature measuring resistance element 18 changes. On the other hand, the resistance value of the ambient temperature measuring resistance element 17 is constant regardless of the change in temperature of the fluid to be measured. Further, when the temperature of the fluid under measurement changes, the ambient temperature sensor including the ambient temperature measuring resistance element 18 measures the temperature after the change of the fluid under measurement. On the other hand, since the ambient temperature sensor including the ambient temperature measuring resistance element 17 measures the temperature of the substrate 11 regardless of the change in the temperature of the fluid to be measured, the measured temperature is constant. Therefore, before and after the temperature change of the fluid to be measured, the difference in resistance value (output voltage) between the ambient temperature resistance element 17 and the ambient temperature resistance element 18 also varies, and the ambient temperature resistance element 18 includes the ambient temperature resistance element 18. The temperature difference calculated by the temperature sensor and the ambient temperature sensor including the ambient temperature measuring resistance element 17 also varies.

図４は、本発明の第１実施形態に係る周囲温度センサに含まれる周囲温度測温抵抗素子１７及び周囲温度測温抵抗素子１８（第１抵抗体）の出力電圧（抵抗値差）と温度差との関係を示すグラフである。上述したとおり、被測定流体の温度が変化すると、図４に示すように、周囲温度測温抵抗素子１７の抵抗値と、周囲温度測温抵抗素子１８の抵抗値と、の差（出力電圧）の変化に対応して、周囲温度測温抵抗素子１７を含む周囲温度センサと、周囲温度測温抵抗素子１８を含む周囲温度センサと、が算出する温度の差も変化する。より具体的には、図４に示すように、上記温度差と上記出力電圧との関係は、一次相関関係である。 FIG. 4 shows the output voltage (resistance value difference) and temperature of the ambient temperature measurement resistance element 17 and the ambient temperature measurement resistance element 18 (first resistor) included in the ambient temperature sensor according to the first embodiment of the present invention. It is a graph which shows the relationship with a difference. As described above, when the temperature of the fluid to be measured changes, as shown in FIG. 4, the difference (output voltage) between the resistance value of the ambient temperature measurement resistance element 17 and the resistance value of the ambient temperature measurement resistance element 18. In response to this change, the difference between the temperatures calculated by the ambient temperature sensor including the ambient temperature measurement resistance element 17 and the ambient temperature sensor including the ambient temperature resistance measurement element 18 also changes. More specifically, as shown in FIG. 4, the relationship between the temperature difference and the output voltage is a primary correlation.

本実施形態における中央演算装置２０は、上述したとおり、被測定流体の温度の変化がある場合に、周囲温度測温抵抗素子１７の抵抗値は一定であることから、周囲温度測温抵抗素子１８（第１抵抗体）の抵抗値の変化量を被測定流体の温度変化として算出する。そして、中央演算装置２０は、周囲温度測温抵抗素子１８（第１抵抗体）の抵抗値の変化量に対応づけられる、被測定流体の流量を補正するための補正値を算出し、当該補正値に基づいて流量を補正する。 As described above, the central processing unit 20 in the present embodiment has a constant resistance value of the ambient temperature resistance thermometer element 17 when there is a change in the temperature of the fluid to be measured. The amount of change in the resistance value of the (first resistor) is calculated as the temperature change of the fluid to be measured. Then, the central processing unit 20 calculates a correction value for correcting the flow rate of the fluid to be measured, which is associated with the amount of change in the resistance value of the ambient temperature measurement resistance element 18 (first resistor), and performs the correction. The flow rate is corrected based on the value.

図１に戻り、流量計測部２２は、熱式流れセンサ１０Ａの上流側測温抵抗素子１５の電気抵抗と下流側測温抵抗素子１６の電気抵抗との差（出力電圧）に対応するセンサ出力に基づいて流路２ａ内を流通する被測定流体の流量（補正前流量）を計測する機能ブロックである。 Returning to FIG. 1, the flow rate measurement unit 22 outputs the sensor output corresponding to the difference (output voltage) between the electrical resistance of the upstream temperature measurement resistance element 15 and the electrical resistance of the downstream temperature measurement resistance element 16 of the thermal flow sensor 10A. Is a functional block for measuring the flow rate of the fluid to be measured (flow rate before correction) flowing through the flow path 2a.

補正値算出部２４は、被測定流体の流量を補正するための補正値を算出する機能ブロックである。補正値算出部２４は、上述したとおり、周囲温度測温抵抗素子１８（第１抵抗体）と周囲温度抵抗素子１７との抵抗値差の変化量、すなわち、上記第１抵抗体の抵抗値の変化量に対応づけられる、被測定流体の流量を補正するための補正値を算出する。より具体的には、補正値算出部２４は、周囲温度測温抵抗素子１８（第１抵抗体）と周囲温度抵抗素子１７との抵抗値差の変化量（上記第１抵抗体の抵抗値の変化量）と、被測定流体の流量を補正するための補正値と、の相関関係を示す関係式又はテーブルをあらかじめ作成し、そして、たとえば被測定流体の温度変化があった際に、上記関係式又はテーブルを参照することによって補正値を算出する。なお、上記補正値は、被測定流体の温度の変化（変化量）に対応づけられるものであってもよく、上記関係式又はテーブルは、被測定流体の温度の変化（変化量）と、被測定流体の流量を補正するための補正値と、の相関関係を示すものであってもよい。 The correction value calculation unit 24 is a functional block that calculates a correction value for correcting the flow rate of the fluid to be measured. As described above, the correction value calculation unit 24 changes the amount of change in the resistance value difference between the ambient temperature resistance element 18 (first resistor) and the ambient temperature resistor element 17, that is, the resistance value of the first resistor. A correction value for correcting the flow rate of the fluid to be measured, which is associated with the amount of change, is calculated. More specifically, the correction value calculation unit 24 changes the amount of change in the resistance value between the ambient temperature resistance element 18 (first resistor) and the ambient temperature resistor element 17 (the resistance value of the first resistor). Change amount) and a correction value or a correction value for correcting the flow rate of the fluid to be measured, a relational expression or a table showing the correlation is created in advance, and when the temperature of the fluid to be measured changes, for example, the above relationship The correction value is calculated by referring to the formula or the table. The correction value may be associated with a change (change amount) in the temperature of the fluid to be measured. It may indicate a correlation with a correction value for correcting the flow rate of the measurement fluid.

流量補正部２６は、補正値算出部２４により算出された補正値に基づいて、被測定流体の流量を補正する機能ブロックである。流量補正部２６は、流量計測部２２が計測した被測定流体の流量（補正前流量）を、たとえば、被測定流体の温度変化があった際に、補正値算出部２４により算出された補正値に基づいて補正前流量を補正し、被測定流体の補正後の流量を得ることができる。 The flow rate correction unit 26 is a functional block that corrects the flow rate of the fluid to be measured based on the correction value calculated by the correction value calculation unit 24. The flow rate correction unit 26 uses the correction value calculated by the correction value calculation unit 24 when the flow rate of the fluid under measurement (flow rate before correction) measured by the flow rate measurement unit 22 changes, for example, when the temperature of the fluid under measurement changes. Based on this, the flow rate before correction can be corrected, and the corrected flow rate of the fluid to be measured can be obtained.

図５は、本発明の第１実施形態に係る流量計１Ａの回路構成例である。上記回路は、例示的に、ヒータ１４に含まれる抵抗素子Ｒｈと、ヒータ１４を駆動するヒータ駆動部５０Ａと、熱式流れセンサ１０Ａに含まれる周囲温度測温抵抗素子１７（ＴＲｒ）、周囲温度測温抵抗素子１８（ＤＲｒ）、抵抗素子Ｒ１、および抵抗素子Ｒ２で構成されるブリッジ回路と、熱式流れセンサ１０Ａを駆動するセンサ駆動部５０Ｂと、計装アンプＵ１と、を備えて構成されている。 FIG. 5 is a circuit configuration example of the flow meter 1A according to the first embodiment of the present invention. The circuit exemplarily includes a resistance element Rh included in the heater 14, a heater driving unit 50A for driving the heater 14, an ambient temperature measuring resistance element 17 (TRr) included in the thermal flow sensor 10A, and an ambient temperature. It comprises a bridge circuit composed of a resistance temperature detector 18 (DRr), a resistance element R1, and a resistance element R2, a sensor driver 50B that drives the thermal flow sensor 10A, and an instrumentation amplifier U1. ing.

ヒータ１４の一端は、ヒータ駆動部５０Ａと接続されており、他端は、ＧＮＤ電位に接続されている。ヒータ駆動部５０Ａは、ヒータ１４の温度が、図２及び図３に示す周囲温度測温抵抗素子１００（図５には不図示）を含む周囲温度センサで計測される温度よりも一定温度高くなるように、ヒータ１４を駆動・制御する。 One end of the heater 14 is connected to the heater driving unit 50A, and the other end is connected to the GND potential. In the heater driving unit 50A, the temperature of the heater 14 is higher than the temperature measured by the ambient temperature sensor including the ambient temperature measuring resistance element 100 (not shown in FIG. 5) shown in FIGS. Thus, the heater 14 is driven and controlled.

計装アンプＵ１の非反転入力端子は、周囲温度測温抵抗素子１７（ＴＲｒ）および周囲温度測温抵抗素子１８（ＤＲｒ）に接続されている。周囲温度測温抵抗素子１７（ＴＲｒ）の他端は、ＧＮＤ電位に接続され、周囲温度測温抵抗素子１８（ＤＲｒ）の他端は、センサ駆動部５０Ｂに接続されている。 The non-inverting input terminal of the instrumentation amplifier U1 is connected to the ambient temperature resistance thermometer element 17 (TRr) and the ambient temperature resistance thermometer element 18 (DRr). The other end of the ambient temperature measurement resistance element 17 (TRr) is connected to the GND potential, and the other end of the ambient temperature measurement resistance element 18 (DRr) is connected to the sensor driving unit 50B.

また、計装アンプＵ１の反転入力端子は、抵抗素子Ｒ１およびＲ２に接続されている。抵抗素子Ｒ１の他端は、センサ駆動部５０Ｂに接続されており、センサ駆動部５０Ｂからブリッジ回路への電位が供給される。抵抗素子Ｒ２の他端は、ＧＮＤ電位に接続されている。 The inverting input terminal of the instrumentation amplifier U1 is connected to the resistance elements R1 and R2. The other end of the resistance element R1 is connected to the sensor driving unit 50B, and a potential is supplied from the sensor driving unit 50B to the bridge circuit. The other end of the resistance element R2 is connected to the GND potential.

ここで、上述したとおり、周囲温度測温抵抗素子１７（ＴＲｒ）、周囲温度測温抵抗素子１８（ＤＲｒ）、抵抗素子Ｒ１、および抵抗素子Ｒ２はブリッジ回路を構成しており、周囲温度測温抵抗素子１７（ＴＲｒ）および周囲温度測温抵抗素子１８（ＤＲｒ）の抵抗値の比と、抵抗素子Ｒ１およびＲ２の抵抗値の比とが等しくなるよう、抵抗素子Ｒ１およびＲ２の値が設定されている。 Here, as described above, the ambient temperature measurement resistance element 17 (TRr), the ambient temperature measurement resistance element 18 (DRr), the resistance element R1, and the resistance element R2 form a bridge circuit. The values of resistance elements R1 and R2 are set so that the ratio of the resistance values of resistance element 17 (TRr) and ambient temperature measuring resistance element 18 (DRr) is equal to the ratio of the resistance values of resistance elements R1 and R2. ing.

計装アンプＵ１は、被測定流体の温度の変化を、周囲温度測温抵抗素子１７（ＴＲｒ）の抵抗値と周囲温度測温抵抗素子１８（ＤＲｒ）の抵抗値との差の変化量、即ち、上述したとおり、周囲温度測温抵抗素子１８（ＤＲｒ）の抵抗値の変化量から検出する。そして、計装アンプＵ１は、周囲温度測温抵抗素子１８（ＤＲｒ）の抵抗値の変化量に対応づけられる、被測定流体の流量を補正するための補正値についての補正値信号を出力する。 The instrumentation amplifier U1 determines the change in the temperature of the fluid to be measured as the amount of change in the difference between the resistance value of the ambient temperature measurement resistance element 17 (TRr) and the resistance value of the ambient temperature measurement resistance element 18 (DRr). As described above, it is detected from the amount of change in the resistance value of the ambient temperature measuring resistance element 18 (DRr). The instrumentation amplifier U1 outputs a correction value signal for a correction value for correcting the flow rate of the fluid to be measured, which is associated with the amount of change in the resistance value of the ambient temperature measuring resistance element 18 (DRr).

図６は、本発明の第１実施形態に係る流量計の流量補正機能を説明するためのフローチャートである。 FIG. 6 is a flowchart for explaining the flow rate correction function of the flow meter according to the first embodiment of the present invention.

図６に示すように、まず、被測定流体の流量（補正前流量）を計測する（ステップＳ１）。 As shown in FIG. 6, first, the flow rate of the fluid to be measured (flow rate before correction) is measured (step S1).

次に、被測定流体の流量を補正するための補正値を算出する（ステップＳ２）。 Next, a correction value for correcting the flow rate of the fluid to be measured is calculated (step S2).

次に、上記補正値に基づいて補正前流量を補正する（ステップＳ３）。 Next, the flow rate before correction is corrected based on the correction value (step S3).

＜第２実施形態＞
図７は、本発明の第２実施形態に係る流量計１（第２実施形態においては１Ｂ）の熱式流れセンサ１０（第２実施形態においては１０Ｂ）の構成を説明するための斜視図である。図８は、図７に示すI−I線に沿った断面図である。 Second Embodiment
FIG. 7 is a perspective view for explaining the configuration of the thermal flow sensor 10 (10B in the second embodiment) of the flow meter 1 (1B in the second embodiment) according to the second embodiment of the present invention. is there. 8 is a cross-sectional view taken along the line II shown in FIG.

図７及び図８に示すように、熱式流れセンサ１０Ｂは、例示的に、キャビティ１２及びキャビティ１９が設けられた基板１１と、基板１１上にキャビティ１２及びキャビティ１９を覆うように配置された絶縁膜１３と、絶縁膜１３に設けられたヒータ１４と、ヒータ１４より上流側に設けられた上流側測温抵抗素子１５と、ヒータ１４より下流側に設けられた下流側測温抵抗素子１６と、上流側測温抵抗素子１５より上流側に設けられた周囲温度測温抵抗素子１７及び周囲温度測温抵抗素子１８（第１抵抗体）と、を備えて構成されている。以下では、第１実施形態と異なる点について特に説明し、他の点については説明を省略する。 As shown in FIGS. 7 and 8, the thermal flow sensor 10 </ b> B is illustratively disposed on the substrate 11 provided with the cavity 12 and the cavity 19, and on the substrate 11 so as to cover the cavity 12 and the cavity 19. Insulating film 13, heater 14 provided on insulating film 13, upstream temperature measuring resistor element 15 provided upstream of heater 14, and downstream temperature measuring resistor element 16 provided downstream of heater 14 And an ambient temperature resistance thermometer element 17 and an ambient temperature resistance thermometer element 18 (first resistor) provided on the upstream side of the upstream resistance thermometer element 15. Below, a different point from 1st Embodiment is demonstrated especially and description is abbreviate | omitted about another point.

図７及び図８に示す本発明の第２実施形態に係る熱式流れセンサ１０Ｂの構成と、図２及び図３に示す本発明の第１実施形態に係る熱式流れセンサ１０Ａの構成との相違点は、熱式流れセンサ１０Ｂが、熱式流れセンサ１０Ａが例示的に備える構成のうち、周囲温度測温抵抗素子１００を備えていない点である。 The configuration of the thermal flow sensor 10B according to the second embodiment of the present invention shown in FIGS. 7 and 8 and the configuration of the thermal flow sensor 10A according to the first embodiment of the present invention shown in FIGS. The difference is that the thermal flow sensor 10B does not include the ambient temperature measuring resistance element 100 in the configuration that the thermal flow sensor 10A exemplarily includes.

図９は、本発明の第２実施形態に係る流量計１Ｂの回路構成例である。上記回路は、例示的に、ヒータ１４に含まれる抵抗素子Ｒｈと、ヒータ１４を駆動するヒータ駆動部５０Ａと、周囲温度測温抵抗素子１７（ＴＲｒ）と、周囲温度測温抵抗素子１８（ＤＲｒ）と、抵抗素子Ｒ１、Ｒ２、Ｒ６、Ｒ７と、熱式流れセンサ１０Ａを駆動するセンサ駆動部５０Ｂと、計装アンプＵ１と、増幅制御部５０Ｃと、を備えて構成されている。図９に示すように、流量計１Ｂの回路構成は、図５に示す本発明の第１実施形態に係る流量計１Ａの回路構成に、増幅制御部５０Ｃと、抵抗素子Ｒ６及びＲ７とをさらに備えるものである。 FIG. 9 is a circuit configuration example of a flow meter 1B according to the second embodiment of the present invention. The circuit exemplarily includes a resistance element Rh included in the heater 14, a heater driving unit 50A that drives the heater 14, an ambient temperature resistance temperature sensor 17 (TRr), and an ambient temperature resistance resistance element 18 (DRr). ), Resistance elements R1, R2, R6, R7, a sensor driving unit 50B for driving the thermal flow sensor 10A, an instrumentation amplifier U1, and an amplification control unit 50C. As shown in FIG. 9, the circuit configuration of the flow meter 1B is the same as the circuit configuration of the flow meter 1A according to the first embodiment of the present invention shown in FIG. 5, except that an amplification control unit 50C and resistance elements R6 and R7 are further provided. It is to be prepared.

図９に示すように、増幅制御部５０Ｃは、例示的に、計装アンプＵ２と、計装アンプＵ２に接続された抵抗素子Ｒ３，Ｒ４，Ｒ５を備えて構成されている。また、抵抗素子Ｒ５の他端は、ＧＮＤ電位に接続されている。また、増幅制御部５０Ｃの計装アンプＵ２の非反転入力端子は、抵抗素子Ｒ１、抵抗素子Ｒ６、及び周囲温度測温抵抗素子１８（ＤＲｒ）と接続されている。さらに、増幅制御部５０Ｃの抵抗素子Ｒ３及びＲ４のそれぞれは、ヒータ駆動部５０Ａと接続されている。 As illustrated in FIG. 9, the amplification control unit 50C is configured to include, for example, an instrumentation amplifier U2 and resistance elements R3, R4, and R5 connected to the instrumentation amplifier U2. The other end of the resistance element R5 is connected to the GND potential. The non-inverting input terminal of the instrumentation amplifier U2 of the amplification controller 50C is connected to the resistance element R1, the resistance element R6, and the ambient temperature measurement resistance element 18 (DRr). Further, each of the resistance elements R3 and R4 of the amplification control unit 50C is connected to the heater driving unit 50A.

図９に示すように、抵抗素子Ｒ６は、センサ駆動部５０Ｂと抵抗素子Ｒ１との間に配置されている。抵抗素子Ｒ６の一端は、センサ駆動部５０Ｂと接続され、他端は、抵抗素子Ｒ１に接続されている。また、抵抗素子Ｒ７は、ヒータ駆動部５０Ａとヒータ１４との間に配置されている。抵抗素子Ｒ７の一端は、ヒータ駆動部５０Ａと接続され、他端は、ヒータ１４に接続されている。 As shown in FIG. 9, the resistance element R6 is disposed between the sensor drive unit 50B and the resistance element R1. One end of the resistance element R6 is connected to the sensor driving unit 50B, and the other end is connected to the resistance element R1. Further, the resistance element R7 is disposed between the heater driving unit 50A and the heater 14. One end of the resistance element R7 is connected to the heater driving unit 50A, and the other end is connected to the heater 14.

流量計１Ｂの上記回路は、周囲温度測温抵抗素子１７（ＴＲｒ）の抵抗値と周囲温度測温抵抗素子１８（ＤＲｒ）の抵抗値との合成抵抗値と抵抗素子Ｒ６の抵抗値との比が、抵抗素子Ｒ７の抵抗値とヒータ１４に含まれる抵抗素子Ｒｈの抵抗値との比と等しくなるように、構成されている。 The above circuit of the flow meter 1B is the ratio of the combined resistance value of the resistance value of the ambient temperature measuring resistance element 17 (TRr) and the resistance value of the ambient temperature measuring resistance element 18 (DRr) and the resistance value of the resistance element R6. Is configured to be equal to the ratio between the resistance value of the resistance element R7 and the resistance value of the resistance element Rh included in the heater 14.

ここで、周囲温度測温抵抗素子１８（ＤＲｒ）は断熱性のダイヤフラム上に設けられる抵抗素子であるため、自己加熱が想定よりも進んでしまうおそれがある。周囲温度測温抵抗素子１８（ＤＲｒ）の自己加熱を所定の範囲内に抑えるためには、周囲温度測温抵抗素子１８（ＤＲｒ）に加わる電圧を下げる必要がある。しかしながら、単に周囲温度測温抵抗素子１８（ＤＲｒ）に加わる電圧を下げてしまうと、ヒータ１４での加熱を十分行うことができなくなる。そこで、増幅制御部５０Ｃは、周囲温度測温抵抗素子１８（ＤＲｒ）に加わる電圧を下げた分だけ増幅して、上記増幅した電圧に対応する制御信号をヒータ駆動部５０Ａに送る。そして、ヒータ駆動部５０Ａは、その制御信号に応じてヒータ１４に電圧を加える。 Here, since the ambient temperature measuring resistance element 18 (DRr) is a resistance element provided on a heat-insulating diaphragm, the self-heating may proceed more than expected. In order to suppress the self-heating of the ambient temperature measurement resistance element 18 (DRr) within a predetermined range, it is necessary to reduce the voltage applied to the ambient temperature measurement resistance element 18 (DRr). However, if the voltage applied to the ambient temperature measuring resistance element 18 (DRr) is simply lowered, the heater 14 cannot be sufficiently heated. Therefore, the amplification control unit 50C amplifies the voltage applied to the ambient temperature measuring resistance element 18 (DRr) by a reduced amount, and sends a control signal corresponding to the amplified voltage to the heater driving unit 50A. Then, the heater driving unit 50A applies a voltage to the heater 14 in accordance with the control signal.

以上説明したように、本発明の第１及び第２実施形態によれば、基板と、上記基板上に配置され、上記基板から熱絶縁された第１抵抗体と、を備える流れセンサにより計測された被測定流体の流量を、補正値算出部により上記第１抵抗体の抵抗値の変化量に対応づけられる、上記流量を補正するための補正値を算出することにより、当該補正値に基づいて被測定流体の流量を補正することができ、被測定流体の流量を正確に計測することができる。 As described above, according to the first and second embodiments of the present invention, the measurement is performed by the flow sensor including the substrate and the first resistor disposed on the substrate and thermally insulated from the substrate. By calculating a correction value for correcting the flow rate, in which the flow rate of the measured fluid is associated with the amount of change in the resistance value of the first resistor by the correction value calculation unit, based on the correction value. The flow rate of the fluid to be measured can be corrected, and the flow rate of the fluid to be measured can be accurately measured.

なお、本発明において、上述した各実施形態は、あくまでも例示であり、明示しない種々の変形や技術の適用を排除する意図はない。即ち、本発明は、その趣旨を逸脱しない範囲で種々変形（各実施形態を組み合わせる等）して実施することができる。 In the present invention, each of the above-described embodiments is merely an example, and there is no intention of excluding various modifications and technical applications that are not explicitly shown. That is, the present invention can be implemented with various modifications (combining the embodiments) without departing from the spirit of the present invention.

１、１Ａ、１Ｂ流量計
２流路保持体
２ａ流路
３計測ユニット
４流入口
５流出口
１０、１０Ａ、１０Ｂ熱式流れセンサ
１１基板
１２キャビティ
１３絶縁膜
１４ヒータ
１５上流側測温抵抗素子
１６下流側測温抵抗素子
１７周囲温度測温抵抗素子
１８周囲温度測温抵抗素子
１９キャビティ
２０中央演算装置
２２流量計測部
２４補正値算出部
２６流量補正部
３０記憶装置
４０表示装置
５０Ａヒータ駆動部
５０Ｂセンサ駆動部
５０Ｃ増幅制御部
Ｒ１〜Ｒ７抵抗
Ｕ１、Ｕ２計装アンプ 1, 1A, 1B Flow meter 2 Flow path holder 2a Flow path 3 Measurement unit 4 Inlet 5 Outlet 10, 10A, 10B Thermal flow sensor 11 Substrate 12 Cavity 13 Insulating film 14 Heater 15 Upstream temperature measuring resistance element 16 Downstream temperature measuring resistance element 17 Ambient temperature resistance resistance element 18 Ambient temperature resistance resistance element 19 Cavity 20 Central processing unit 22 Flow rate measurement unit 24 Correction value calculation unit 26 Flow rate correction unit 30 Storage device 40 Display device 50A Heater drive unit 50B Sensor drive unit 50C Amplification control unit R1-R7 Resistors U1, U2 Instrumentation amplifier

Claims

A flow sensor that measures the flow rate of the fluid to be measured, and a correction value calculation unit that calculates a correction value for correcting the measured flow rate,
The flow sensor is
A substrate,
A first resistor arranged to be strongly influenced by the temperature of the fluid to be measured;
A second resistor disposed so as to be strongly influenced by the temperature of the substrate,
The flow sensor conveys heat applied by a heater controlled so as to be higher than a temperature measured by an ambient temperature sensor including the first resistor in a downstream direction of the flow of the fluid to be measured. Due to the effect, the downstream resistance element provided on the downstream side of the flow of the fluid to be measured from the heater rather than the temperature of the upstream resistance element provided on the upstream side of the flow of the fluid to be measured from the heater. The flow rate of the fluid to be measured is measured based on the difference between the electrical resistance of the upstream resistance temperature sensor element and the electrical resistance of the downstream resistance temperature sensor element when the temperature of
The correction value calculation unit calculates a correction value for correcting the flow rate, which is associated with a change amount of a difference between the resistance value of the first resistor and the resistance value of the second resistor.
Flowmeter.

A flow rate correction unit for correcting the flow rate;
The flow rate correction unit corrects the flow rate based on the correction value.
The flow meter according to claim 1.

A storage unit that stores a relational expression or a table indicating a correlation between the amount of change in the resistance value of the first resistor and the correction value;
The flow meter according to claim 1 or 2.

Measuring the flow rate of the fluid to be measured with a flow sensor;
Calculating a correction value for correcting the measured flow rate,
The flow sensor is
A substrate,
A first resistor arranged to be strongly influenced by the temperature of the fluid to be measured;
A second resistor disposed so as to be strongly influenced by the temperature of the substrate,
In the step of measuring the flow rate, the heat applied by the heater controlled so as to be higher than the temperature measured by the ambient temperature sensor including the first resistor is in the downstream direction of the flow of the fluid to be measured. Due to the transport effect carried, the downstream side measurement provided on the downstream side of the flow of the fluid to be measured from the heater rather than the temperature of the upstream resistance temperature element provided on the upstream side of the flow of the fluid to be measured from the heater. A step of measuring the flow rate of the fluid to be measured based on the difference between the electrical resistance of the upstream resistance temperature measuring element and the electrical resistance of the downstream temperature sensing resistance element when the temperature of the temperature resistance element becomes high Including
The step of calculating the correction value is a step of calculating a correction value for correcting the flow rate, which is associated with a change amount of a difference between the resistance value of the first resistor and the resistance value of the second resistor. including,
Correction value calculation method.