WO2020080189A1 - Flow rate measuring device, and method for controlling flow rate measuring device - Google Patents

Flow rate measuring device, and method for controlling flow rate measuring device Download PDF

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Publication number
WO2020080189A1
WO2020080189A1 PCT/JP2019/039642 JP2019039642W WO2020080189A1 WO 2020080189 A1 WO2020080189 A1 WO 2020080189A1 JP 2019039642 W JP2019039642 W JP 2019039642W WO 2020080189 A1 WO2020080189 A1 WO 2020080189A1
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WIPO (PCT)
Prior art keywords
flow rate
fluid
output
unit
temperature
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PCT/JP2019/039642
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French (fr)
Japanese (ja)
Inventor
憲一 半田
秀之 中尾
克行 山本
工藤　卓也
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オムロン株式会社
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Publication of WO2020080189A1 publication Critical patent/WO2020080189A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/696—Circuits therefor, e.g. constant-current flow meters

Definitions

  • the present invention relates to a flow rate measuring device and a control method of the flow rate measuring device.
  • a measuring device that includes a heater and a sensor and calculates the flow velocity or the flow rate of the fluid by detecting the degree to which the temperature distribution caused by the heat generation of the heater changes due to the flow of the fluid.
  • a flow rate detection unit for detecting the flow rate of the measurement target fluid flowing through the main flow path, a heating unit for heating the measurement target fluid and a temperature detection unit for detecting the temperature of the measurement target fluid, and the characteristics of the measurement target fluid.
  • the flow rate of the measurement target fluid calculated based on the detection signal output from the flow rate detection unit using the characteristic value acquisition unit for acquiring the value and the characteristic value of the measurement target fluid acquired by the characteristic value acquisition unit.
  • the heating unit and the temperature detection unit are arranged side by side in a direction orthogonal to the flow direction of the fluid to be measured, and the characteristic value acquisition unit changes the temperature of the heating unit.
  • a flow rate measuring device that acquires a characteristic value based on a difference in temperature of a fluid to be measured detected by a temperature detection unit before and after (for example, refer to Patent Document 1).
  • the flow rate detection unit also has a heating unit that heats the measurement target fluid and a temperature detection unit that detects the temperature of the measurement target fluid.
  • the temperature detectors are arranged side by side in the flow direction of the fluid to be measured.
  • the measurement error may increase.
  • the flow rate of the fluid belongs to the range of medium flow rate to high flow rate, by measuring the flow rate based on the temperature obtained by the temperature detection unit arranged on the upstream side in the flow direction of the heating unit, It has been experimentally known that expansion of measurement error can be suppressed.
  • the flow rate of the fluid belongs to the region of medium flow rate to high flow rate
  • the flow rate can be measured based on the temperature obtained by the temperature detection unit arranged on the upstream side in the flow direction of the heating unit. The decrease in measurement accuracy was suppressed.
  • the present invention has been made in view of the above situation, and an object thereof is to have a heating unit that heats a measurement target fluid and a temperature detection unit that detects the temperature of the measurement target fluid, and the heating unit and the temperature.
  • the detection unit is arranged side by side in the flow direction of the fluid to be measured, even if there is a temperature difference between the fluid temperature and the environmental temperature, in the range of medium to large flow rate , It is to provide a technique capable of measuring a flow rate with higher accuracy.
  • the present invention for solving the above problems is a flow rate measuring device for measuring the flow rate of a fluid to be measured flowing through a flow path, A heating unit for heating the fluid to be measured, A plurality of temperature detection units arranged on both sides of the heating unit with the heating unit sandwiched in the flow direction of the measurement target fluid, for detecting the temperature of the measurement target fluid, A first flow rate calculation unit that calculates the flow rate of the fluid to be measured from the difference between the output values of the temperature detection units arranged on both sides of the heating unit, A second flow rate calculation unit for calculating the flow rate of the fluid to be measured from the output value of the temperature detection unit arranged on one side of the heating unit, Equipped with When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated by the second flow rate calculation unit is output, and the range of the flow rate of the measurement target fluid is the predetermined condition.
  • an output control unit that outputs the flow rate of the measurement target fluid calculated by the first flow rate calculation unit, It is a flow measuring device characterized by further comprising.
  • the heating unit for heating the measurement target fluid and the temperature detection unit for detecting the temperature of the measurement target fluid are provided, and the temperature detection unit has the heating units on both sides of the heating unit in the flow direction of the measurement target fluid. If the flow rate of the fluid to be measured satisfies a predetermined condition, the fluid to be measured calculated from the output value of the temperature detection unit placed on one side of the heating unit Output the flow rate of. Then, even when the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated from the output value of the temperature detection unit arranged on one side of the heating unit, and the heating unit.
  • the predetermined condition may be that the flow rate belongs to a predetermined medium to large flow rate region.
  • the accuracy required for the flow rate measuring device is set to be severe at a predetermined flow rate value (for example, 5 to 10 L / min) or more. It may be a predetermined flow rate value (for example, 5 to 10 L / min) or more at which the required accuracy in the industrial standard is improved. Under this condition, as long as the fluid temperature is stable and the temperature difference between the fluid temperature and the ambient temperature is small, the flow rate of the fluid to be measured can be calculated from the difference between the output values of the temperature detection units arranged on both sides of the heating unit.
  • the first flow rate calculation unit The difference between the output values of the temperature detection units arranged on both sides of the heating unit is corrected and calculated by using a conversion data table including conversion data set corresponding to a predetermined number of difference values, thereby determining the flow rate.
  • the second flow rate calculation unit The flow rate is calculated by correcting the output value of the temperature detecting unit arranged on one side of the heating unit using a conversion data table including conversion data set corresponding to a predetermined number of difference values.
  • Has a second correction calculation unit The output control unit, when the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated by the first polynomial calculation unit by the first flow rate calculation unit, and When the deviation between the flow rate of the fluid to be measured calculated by the second correction calculation section by the second flow rate calculation section is equal to or more than the predetermined value, the measurement target calculated by the first flow rate calculation section
  • the fluid flow rate may be output.
  • the first flow rate calculation unit calculates the flow rate using the first correction calculation unit
  • the second flow rate calculation unit uses the second correction calculation unit.
  • the flow rate is often calculated.
  • the difference between the output values of the temperature detection units arranged on both sides of the heating unit or the relationship between the output value of the temperature detection unit arranged on one side of the heating unit and the flow rate of the fluid is calculated by this correction calculation. This is to improve the accuracy of flow rate measurement by approaching a linear relationship that passes through.
  • the flow rate calculated from the output value of the temperature detection unit arranged on one side of the heating unit when the range of the flow rate of the fluid to be measured satisfies a predetermined condition, the flow rate calculated from the output value of the temperature detection unit arranged on one side of the heating unit, and the heating unit.
  • the deviation from the flow rate calculated from the difference between the output values of the temperature detectors arranged on both sides of the temperature difference is equal to or greater than a predetermined value, there is a temperature difference between the fluid temperature and the environmental temperature. Cannot be used as it is, and it is necessary to further store a dedicated conversion data table.
  • the flow rate is calculated by performing a polynomial operation on the difference between the output values of the temperature detection units arranged on both sides of the heating unit. According to this, conversion can be performed by storing the data corresponding to the coefficient of the polynomial used for the calculation, and the required memory capacity can be reduced as compared with the case of performing the correction calculation. As a result, the flow rate measuring device can be further simplified or the cost can be further reduced.
  • a heating unit for heating the fluid to be measured A plurality of temperature detection units arranged on both sides of the heating unit with the heating unit sandwiched in the flow direction of the measurement target fluid, for detecting the temperature of the measurement target fluid, A flow rate calculation unit that calculates the flow rate of the fluid to be measured from the output value of the temperature detection unit, A method of controlling a flow rate measuring device, comprising: A first flow rate calculating step of calculating the flow rate of the fluid to be measured from the difference between the output values of the temperature detecting sections arranged on both sides of the heating section, A second flow rate calculating step of calculating the flow rate of the fluid to be measured from the output value of the temperature detecting section arranged on one side of the heating section, When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated in the second flow rate calculation step is output, and the range of the flow rate of the measurement target fluid is the predetermined range.
  • the control method of the flow rate measuring device may be characterized by including the following.
  • the present invention may be the control method of the above flow rate measuring device, wherein the predetermined condition is that the flow rate belongs to a predetermined medium flow rate to high flow rate region.
  • the first flow rate calculation step is The difference between the output values of the temperature detection units arranged on both sides of the heating unit is corrected and calculated by using a conversion data table including conversion data set corresponding to a predetermined number of difference values, thereby determining the flow rate.
  • a first correction calculation step for calculating The difference between the output values of the temperature detection units arranged on both sides of the heating unit, by performing a polynomial calculation, a first polynomial calculation step of calculating the flow rate, and having a selectable,
  • the second flow rate calculation step The flow rate is calculated by correcting the output value of the temperature detecting unit arranged on one side of the heating unit using a conversion data table including conversion data set corresponding to a predetermined number of difference values.
  • Has a second correction calculation step In the output step, When the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated by the first polynomial calculation step in the first flow rate calculation step, and the second flow rate calculation If the deviation from the flow rate of the fluid to be measured calculated in the second correction calculation step in the step is not less than the predetermined value, it is calculated in the first polynomial calculation step in the first flow rate calculation step.
  • the control method of the above flow rate measuring device may be characterized in that the flow rate of the fluid to be measured is output.
  • the means for solving the above problems in the present invention can be used in combination as much as possible.
  • the heating unit for heating the measurement target fluid and the temperature detection unit for detecting the temperature of the measurement target fluid are provided, and the heating unit and the temperature detection unit are arranged side by side in the flow direction of the measurement target fluid.
  • the flow rate measuring device even when there is a temperature difference between the fluid temperature and the environmental temperature, the flow rate can be measured with higher accuracy in the range of medium flow rate to high flow rate. As a result, it is possible to realize a flow rate measuring device capable of maintaining measurement accuracy that can be practically used in a wider variety of measurement environments.
  • FIG. 1 It is an exploded perspective view showing an example of a flow measuring device in an example of the present invention. It is sectional drawing which shows an example of the flow measuring device in the Example of this invention. It is a top view which shows the sub flow path part in the Example of this invention. It is a perspective view which shows an example of the sensor element in the Example of this invention. It is sectional drawing for demonstrating the mechanism of the sensor element in the Example of this invention. It is a top view which shows schematic structure of the flow volume detection part in the Example of this invention. It is a top view showing a schematic structure of a physical property value detecting part in an example of the present invention. It is a block diagram which shows the function structure of the flow measuring device in the Example of this invention.
  • FIG. 6 is a diagram showing a change in output of a temperature detection unit on one side when a fluid temperature changes abruptly in an example of the present invention.
  • 3 is a flowchart showing the control contents of a flow rate measurement routine 1 in the first embodiment of the present invention. It is a graph which shows the output example of the flow measuring device in Example 1 of the present invention.
  • FIG. 7 is a diagram for explaining correction calculation of an output of the temperature detection unit in the second embodiment of the present invention.
  • the present invention is applied to, for example, a thermal type flow rate measuring device 1 as shown in FIG.
  • the flow rate measuring device 1 is installed in, for example, a gas meter, a combustion device, an internal combustion engine such as an automobile, a fuel cell, other industrial devices such as medical equipment, and a built-in device, and measures the amount of fluid passing through the flow path.
  • the flow rate measuring device 1 diverts the fluid flowing through the main flow path portion 2 and guides a part of the fluid to the flow rate detecting portion 11, which has a high correlation with the flow rate of the fluid in the main flow path portion 2.
  • the flow rate in the flow rate detector 11 is measured.
  • the sensor element used in the flow rate detection unit 11 has a configuration in which two thermopiles 102 are arranged with a microheater (heating unit) 101 interposed therebetween.
  • the correlation between the difference between the detected temperature values detected by the two thermopiles 102 and the flow rate of the fluid passing therethrough is used.
  • the output of the flow rate detection unit 11 is the detection value acquisition unit 131 of the control unit 13 realized by the CPU (Central Processing Unit) arranged on the circuit board 5.
  • the flow rate calculation unit 133 calculates the flow rate as the final output.
  • a storage unit (memory: not shown) for realizing the functions of the control unit 13 is also arranged on the circuit board 5.
  • This application example relates to control of the flow rate measuring device 1 as described above.
  • the fluid calculated from the output value of the thermopile 102 temperature detection unit 111 arranged on the upstream side of the microheater 101. It is assumed that the flow rate of is output. This is because it is known that under the above conditions, the accuracy of the fluid flow rate calculated from the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the microheater 101 decreases. Is.
  • the output value of the thermopile 102 (temperature detection unit 111) arranged on the upstream side of the microheater 101
  • the deviation between the calculated flow rate of the measurement target fluid and the flow rate of the measurement target fluid calculated from the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the micro-heater 101 is predetermined.
  • the flow rate of the fluid to be measured calculated based on the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the microheater 101 is output.
  • thermopile 102 temperature detecting unit arranged upstream of the micro heater 101 is used. This is because it can be determined that the accuracy of the flow rate of the fluid to be measured calculated from the output value of (111) has significantly decreased.
  • thermopile 102 temperature detection unit disposed on the upstream side of the microheater 101.
  • the difference between the output values of the thermopiles 102 temperature detection units 111 and 112 arranged on both sides of the microheater 101.
  • the calculated flow rate of the fluid to be measured can be output. As a result, the measurement accuracy of the flow rate measuring device 1 can be maintained in a wider variety of measurement environments.
  • the difference between the output values of the thermopiles 102 (temperature detecting units 111 and 112) arranged on both sides of the micro-heater 101 is as shown in FIG.
  • the flow rate is calculated by performing a correction calculation to perform the correction. This is because the correction calculation brings the relationship between the output of the flow rate measuring device 1 and the flow rate close to the linear relationship passing through the origin, as shown by the line (4) in FIG.
  • a dedicated conversion data table is further stored. You need to do it.
  • the flow rate is calculated by performing a polynomial calculation as shown in FIG. 15 on the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the microheater 101. And According to this, by storing the data corresponding to the coefficients a, b, c, and d of the polynomial used for the calculation, it is possible to reduce the required memory capacity as compared with the case where the correction calculation is performed. Become.
  • FIG. 1 is an exploded perspective view showing an example of a flow rate measuring device 1 according to this embodiment.
  • FIG. 2 is a sectional view showing an example of the flow rate measuring device 1.
  • the broken line arrows in FIGS. 1 and 2 exemplify the direction in which the fluid flows.
  • the flow rate measuring device 1 according to the present embodiment includes a main flow path portion 2, a sub flow path portion 3, a seal 4, a circuit board 5, and a cover 6.
  • the flow rate measuring device 1 has a sub-flow passage section 3 branched from the main flow passage section 2.
  • the sub-flow path unit 3 is provided with a flow rate detection unit 11 and a physical property value detection unit 12.
  • the flow rate detecting unit 11 and the physical property value detecting unit 12 are configured by a thermal type flow sensor including a heating unit formed by a micro heater and a temperature detecting unit formed by a thermopile. Further, in the present embodiment, the physical property value of the fluid is detected by using the physical property value detection unit 12, and the flow rate detected by the flow rate detection unit 11 is corrected based on the physical property value of the fluid.
  • the device 1 does not necessarily have to include the physical property value detection unit 12.
  • the main flow path part 2 is a tubular member through which a flow path of a fluid to be measured (hereinafter, also referred to as a main flow path) penetrates in the longitudinal direction.
  • a flow path of a fluid to be measured hereinafter, also referred to as a main flow path
  • an inlet (first inlet) 34A is formed on the upstream side and an outlet (first inlet) on the downstream side in the inner peripheral surface of the main flow path portion 2 in the flow direction of the fluid.
  • Outflow port) 35A is formed.
  • the length of the main flow path portion 2 in the axial direction is about 50 mm
  • the diameter of the inner peripheral surface (inner diameter of the main flow path portion 2) is about 20 mm
  • the outer diameter of the main flow path portion 2 is about 24 mm.
  • the dimensions of the main flow path portion 2 are not limited to these.
  • the orifice 21 is provided between the inflow port 34A and the outflow port 35A.
  • the orifice 21 is a resistor having an inner diameter smaller than that in the front and the rear of the main flow path portion 2, and the amount of fluid flowing into the sub flow path portion 3 can be adjusted by the size of the orifice 21.
  • the sub-flow passage portion 3 which is a portion including the sub-flow passage branched from the main flow passage therein is provided above the main flow passage portion 2 in the vertical direction.
  • the sub-flow paths in the sub-flow path portion 3 include an inflow flow path 34, a physical property value detection flow path 32, a flow rate detection flow path 33, and an outflow flow path 35. A part of the fluid flowing through the main flow path portion 2 branches into the sub flow path portion 3 and flows into the sub flow path portion 3.
  • the inflow passage 34 is a passage for inflowing the fluid flowing through the main passage portion 2 and splitting the fluid into the physical property value detecting passage 32 and the flow amount detecting passage 33.
  • the inflow passage 34 is formed along a direction perpendicular to the flow direction of the fluid in the main passage portion 2, one end thereof is connected to the inflow port 34A, and the other end is connected to the physical property value detection passage 32 and the flow amount detection. It is connected to the flow channel 33.
  • a part of the fluid flowing through the main flow path portion 2 is further divided into the physical property value detection flow path 32 and the flow rate detection flow path 33 via the inflow flow path 34.
  • the flow rate detection unit 11 can detect a value according to the amount of fluid flowing through the main flow path unit 2.
  • the physical property value detection flow channel 32 is formed vertically above the main flow channel portion 2, extends in a direction parallel to the main flow channel portion 2, and has a substantially U-shaped cross section when viewed from above. Is the flow path.
  • the physical property value detection flow path 32 has therein the physical property value detection unit 12 for detecting the physical property value of the fluid to be measured.
  • One end of the physical property value detection flow path 32 is connected to the inflow flow path 34, and the other end is connected to the outflow flow path 35.
  • the flow rate detecting flow path 33 is also a flow path that extends in a direction parallel to the flow direction of the fluid in the main flow path portion 2 and has a substantially U-shaped cross section as viewed from above.
  • the flow rate detection flow path 33 has therein a flow rate detection unit 11 for detecting the flow rate of the fluid. Further, one end of the flow rate detection flow path 33 is connected to the inflow flow path 34, and the other end is connected to the outflow flow path 35.
  • the physical property value detector 12 and the flow rate detector 11 are mounted on the circuit board 5, respectively. Then, the circuit board 5 covers the upper portions of the physical property value detection flow channel 32 and the flow rate detection flow channel 33, which are open at the top, and the physical property value detection unit 12 is located in the physical property value detection flow channel 32.
  • the flow rate detection unit 11 is arranged in the detection flow path 33.
  • the outflow channel 35 is a channel for allowing the measurement target fluid that has passed through the physical property value detection channel 32 and the flow rate detection channel 33 to flow out to the main channel section 2.
  • the outflow passage 35 is formed along the direction perpendicular to the main flow passage portion 2, one end thereof is connected to the outflow port 35A, and the other end is connected to the physical property value detection passage 32 and the flow amount detection passage 33. It is connected.
  • the measurement target fluid that has passed through the physical property value detection flow path 32 and the flow rate detection flow path 33 flows out to the main flow path unit 2 via the outflow flow path 35.
  • the fluid to be measured which has flowed in from one inflow port 34A, is split into the physical property value detection flow channel 32 and the flow rate detection flow channel 33. Accordingly, the flow rate detection unit 11 and the physical property value detection unit 12 can detect the physical property value and the flow rate of the fluid to be measured, based on the fluids having substantially the same conditions such as temperature and density.
  • the circuit board 5 is arranged after the seal 4 is fitted in the sub-flow passage portion 3, and the circuit board 5 is fixed to the sub-flow passage portion 3 by the cover 6, so that the side flow The airtightness of the inside of the road portion 3 is ensured.
  • FIG. 3 is a plan view of the sub-flow path portion 3 shown in FIG.
  • the physical property value detection flow path 32 and the flow rate detection flow path 33 are arranged symmetrically with respect to a line (not shown) connecting the inflow flow path 34 and the outflow flow path 35.
  • arrows P and Q schematically show the ratio of the flow rates of the fluids divided into the physical property value detection flow channel 32 and the flow rate detection flow channel 33.
  • the cross-sectional areas of the physical property value detection flow channel 32 and the flow rate detection flow channel 33 are determined such that the amount of the divided fluid is P: Q.
  • the amount of the fluid actually flowing through the physical property value detecting flow path 32 and the flow rate detecting flow path 33 varies depending on the flow rate of the fluid flowing through the main flow path portion 2.
  • the amount of fluid flowing through the passage 32 becomes a value within the detection range of the physical property value detection unit 12
  • the amount of fluid flowing through the flow rate detection flow channel 33 becomes a value within the detection range of the flow rate detection unit 11
  • the size of the sub-flow passage portion 3 with respect to the portion 2 and the size of the orifice 21, and the widths of the physical property value detection flow passage 32 and the flow rate detection flow passage 33 are set.
  • the widths of the physical property value detection flow channel 32 and the flow rate detection flow channel 33 are mere examples, and are not limited to the example shown in FIG.
  • the amount of fluid flowing through the physical property value detection flow channel 32 and the flow rate detection flow channel 33 is smaller than the amount of fluid flowing through the main flow channel unit 2, but the amount of fluid flowing through each of the main flow channel units 2 is large. Change according to. If the flow rate detection unit 11 and the physical property value detection unit 12 are arranged in the main flow channel unit 2, it is necessary to increase the scales of the flow rate detection unit 11 and the physical property value detection unit 12 according to the amount of fluid flowing through the main flow channel unit 2. However, in the present embodiment, by providing the sub-flow path section 3 that branches from the main flow path section 2, the flow rate of the fluid can be measured by the small-scale flow rate detection section 11 and the physical property value detection section 12.
  • FIG. 4 is a perspective view showing an example of a sensor element used in the flow rate detection unit 11 and the physical property value detection unit 12.
  • FIG. 5 is a cross-sectional view for explaining the mechanism of the sensor element.
  • the sensor element 100 includes a micro heater (also referred to as a heating unit) 101, and two thermopiles (also referred to as a temperature detection unit) 102 that are symmetrically provided with the micro heater 101 interposed therebetween. That is, the micro-heater 101 and the two thermopiles 102 are arranged so as to be aligned in a predetermined direction. As shown in FIG.
  • an insulating thin film 103 is formed above and below these, and the micro heater 101, the thermopile 102, and the insulating thin film 103 are provided on a silicon base 104. Further, a cavity 105 formed by etching or the like is provided in the silicon base 104 below the micro heater 101 and the thermopile 102.
  • the micro heater 101 is, for example, a resistor formed of polysilicon.
  • a dashed ellipse schematically shows the temperature distribution when the microheater 101 generates heat. The thicker the broken line, the higher the temperature.
  • the temperature distribution around the micro-heater 101 becomes substantially uniform as shown in FIG.
  • the sensor element 100 outputs a value indicating the flow rate by utilizing such uneven distribution of the heater heat.
  • the output voltage ⁇ V of the sensor element is expressed by the following equation (1), for example.
  • Th is the temperature of the microheater 101 (the temperature of the end of the thermopile 102 on the microheater 101 side)
  • Ta is the lower temperature of the end of the thermopile 102 on the side far from the microheater 101 (see FIG. In a), the temperature at the left end of the left thermopile 102 or the temperature at the right end of the right thermopile 102, and in FIG. 5B, the temperature at the left end of the left thermopile 102, which is the upstream end),
  • Vf Average values, A and b are predetermined constants.
  • FIG. 6 is a plan view showing a schematic configuration of the flow rate detection unit 11 shown in FIG. 1
  • FIG. 7 is a plan view showing a schematic configuration of the physical property value detection unit 12 shown in FIG.
  • the flow rate detection unit 11 includes a first thermopile (also referred to as a temperature detection unit) 111 and a second thermopile (also referred to as a temperature detection unit) 112 that detect the temperature of a measurement target fluid, and a measurement target fluid.
  • a micro-heater also referred to as a heating unit 113 for heating.
  • the heating unit 113, the temperature detecting unit 111, and the temperature detecting unit 112 are arranged in the flow rate detecting unit 11 side by side along the arrow P in the flow direction of the fluid to be measured.
  • the shapes of the heating unit 113, the temperature detecting unit 111, and the temperature detecting unit 112 are substantially rectangular in plan view, and the longitudinal direction of each is orthogonal to the arrow P of the flow direction of the fluid to be measured.
  • the temperature detection unit 111 is arranged on the upstream side of the heating unit 113, and the temperature detection unit 112 is arranged on the downstream side, so that the temperature at symmetrical positions with the heating unit 113 in between is detected.
  • the sensor element 100 having substantially the same structure is used for the flow rate detection unit 11 and the physical property value detection unit 12, and the arrangement angle of the sensor element 100 with respect to the flow direction of the fluid is determined by a plan view of the sensor element 100. They are arranged 90 degrees apart. Thereby, the sensor element 100 having the same structure can be used for the flow rate detection unit 11 and the physical property value detection unit 12, and the manufacturing cost of the flow rate measurement device 1 can be suppressed.
  • the physical property value detection unit 12 includes a first thermopile (also referred to as a temperature detection unit) 121 and a second thermopile (also referred to as a temperature detection unit) 122 that detect the temperature of the fluid to be measured. , And a micro heater (also referred to as a heating unit) 123 for heating the fluid to be measured.
  • the heating unit 123, the temperature detecting unit 121, and the temperature detecting unit 122 are arranged in the physical property value detecting unit 12 side by side in a direction orthogonal to the flow direction Q of the fluid to be measured.
  • the shapes of the heating unit 123, the temperature detecting unit 121, and the temperature detecting unit 122 are substantially rectangular in a plan view, and the longitudinal direction of each is along the flow direction Q of the fluid to be measured. Further, the temperature detection unit 121 and the temperature detection unit 122 are arranged symmetrically with the heating unit 123 in between, and detect temperatures at symmetrical positions on both sides of the heating unit 123. Therefore, the measured values of the temperature detection unit 121 and the temperature detection unit 122 are almost the same, and the average value may be adopted, or either one of them may be adopted.
  • FIG. 8 is a functional block diagram showing an example of the functional configuration of the flow rate measuring device 1.
  • the flow rate measurement device 1 includes a flow rate detection unit 11, a physical property value detection unit 12, a control unit 13, and a communication unit 15.
  • the flow rate detection unit 11 includes a temperature detection unit 111 and a temperature detection unit 112.
  • the physical property value detection unit 12 includes a temperature detection unit 121 and a temperature detection unit 122. It should be noted that the heating unit 113 shown in FIG. 6 and the heating unit 123 shown in FIG. 7 are not shown.
  • the control unit 13 also includes a detection value acquisition unit 131, a characteristic value calculation unit 132, a flow rate calculation unit 133, and an output control unit 135.
  • the flow rate detection unit 11 outputs a signal according to the temperature detected by the temperature detection unit 111 and a signal according to the temperature detected by the temperature detection unit 112 to the detection value acquisition unit 131 of the control unit 13.
  • the physical property value detection unit 12 outputs a signal corresponding to the temperature detected by the temperature detection unit 121 to the characteristic value calculation unit 132.
  • the physical property value detection unit 12 may obtain an average value of signals according to the temperatures detected by the temperature detection unit 121 and the temperature detection unit 122 and output the average value to the characteristic value calculation unit 132. Alternatively, either the temperature detecting unit 121 or the temperature detecting unit 122 may be used to acquire a signal according to the temperature.
  • the detection value acquisition unit 131 acquires the detection value of the temperature output by the temperature detection unit 111 and the temperature detection unit 112 in the flow rate detection unit 11 at a predetermined measurement interval, and the detection value of the temperature by the temperature detection unit 111 or the temperature The difference between the temperature detection values of the detection unit 111 and the temperature detection unit 112 is output.
  • the characteristic value calculation unit 132 calculates the characteristic value based on the detection value of at least one of the temperature detection unit 121 and the temperature detection unit 122 of the physical property value detection unit 12.
  • the characteristic value calculation unit 132 changes the temperature of the micro heater of the physical property value detection unit 12, and a predetermined coefficient is used for the difference between the temperatures of the fluid to be measured detected by the temperature detection unit 121 and the temperature detection unit 122 before and after the change.
  • the characteristic value may be calculated by multiplying by.
  • the flow rate calculation unit 133 calculates the flow rate of the fluid based on the output of the detection value acquisition unit 131. At this time, the flow rate calculation unit 133 may correct the flow rate by using the characteristic value calculated by the physical property value detection unit 12.
  • the output control unit 135 calculates a flow rate calculated from either the temperature detection value output by the detection value acquisition unit 131 by the temperature detection unit 111 or the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112. Is output from the flow rate calculation unit 133.
  • the communication unit 15 wirelessly or wiredly transmits the information processed by the control unit 13 to the outside, receives commands or set values from the outside wirelessly or by wire, and transmits them to the control unit 13.
  • FIG. 9 shows a more detailed functional block diagram of the flow rate calculation unit 133.
  • the flow rate calculation unit 133 is provided with a first flow rate calculation unit 136 and a second flow rate calculation unit 137.
  • the first flow rate calculation unit 136 has a function of calculating the flow rate of the fluid from the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112.
  • the second flow rate calculation unit 137 has a function of calculating the flow rate of the fluid based on the temperature detection value of the temperature detection unit 111 arranged on the upstream side of the heating unit 113.
  • the first flow rate calculation unit 136 corrects the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112 using a conversion data table including conversion data set corresponding to the difference value.
  • the first correction calculation unit 136a that calculates the flow rate of the fluid and the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112 are calculated by polynomial calculation.
  • the second flow rate calculation unit 137 uses the conversion data table including the conversion data set for the output value of the temperature detection unit 111 arranged on the upstream side of the heating unit 113, corresponding to the difference value.
  • a second correction calculation unit 137a that calculates the flow rate by performing the correction calculation is provided.
  • the flow rate calculation unit 133 of the flow rate measurement device 1 basically calculates the flow rate of the fluid based on the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112.
  • the flow rate of TA1 output that is the detection value of the temperature detection unit 111, TB1 output that is the detection value of the temperature detection unit 112, and FV1 output that is the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112. Shows the change with respect to.
  • the output control unit 135 calculates the flow rate in the flow rate calculation unit 133 using only the TA1 output that is the detection value of the temperature detection unit 111, I was trying to output. This is because, when the flow rate of the fluid belongs to the region of medium flow rate to high flow rate, it is more accurate to use the TA1 output, which is the detection value of the temperature detection unit 111, as the detection value than the FV1 output as the detection value. This is because it was experimentally known that a good flow rate of Here, when the flow rate belongs to a medium flow rate to high flow rate region such as the region B and the region C, it corresponds to the predetermined condition in the present embodiment.
  • the temperature The output of the detection unit 111 may be extremely unstable and may change.
  • FIG. 11A the horizontal axis represents time and the vertical axis represents fluid temperature.
  • the fluid temperature is stable until time t1, but the fluid temperature rises sharply between times t1 and t2, and time t2.
  • the following shows the case where it becomes stable again. In such a case, the fluid temperature is equal to the environmental temperature until the time t1.
  • the fluid temperature rises sharply to cause a temperature difference between the fluid temperature and the environment temperature, and after time t2, the environment temperature rises similarly to the fluid temperature, so that the fluid temperature is increased again.
  • the temperature is the same as the ambient temperature.
  • FIG. 11B shows a change in the TA1 output which is the output of the temperature detection unit 111 in the above state. Note that here, the case where the range of the flow rate is the region B is shown. As shown in FIG. 11B, when the fluid temperature changes abruptly and a temperature difference occurs between the fluid temperature and the ambient temperature, the TA1 output becomes extremely unstable, and accurate flow rate measurement is performed. In some cases, it became impossible.
  • the fluid flow rate is calculated based on the FV1 output, which is the difference between the TA1 output and the TB1 output, instead of the TA1 output. Further, it is detected that the TA1 output is extremely unstable as indicated by t1 to t2 in FIG. 11B by the deviation between the TA1 output and the FV1 output being equal to or more than a predetermined threshold value. I chose
  • FIG. 12 shows a flow chart of the flow rate measurement routine 1 in this embodiment.
  • This routine is a program stored in the memory provided in the circuit board 5, and is executed by the flow rate calculation unit 133 of the control unit 13 at predetermined time intervals.
  • step S101 it is determined in step S101 whether the flow rate of the fluid belongs to the area A.
  • the fluid flow rate is low, and based on the FV1 output that is the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112. , It is determined that there is no problem even if the flow rate of the fluid is calculated, so the process proceeds to step S103.
  • the fluid flow rate belongs to the area B or the area C, and the FV1 output that is the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112 is output. If the flow rate of the fluid is calculated based on this, it is determined that the measurement accuracy will decrease, so the process proceeds to step S102.
  • step S102 the flow rate calculation unit 133 calculates the flow rate FVO (TA1) based only on the TA1 output that is the detection value of the temperature detection unit 111.
  • step S104 the flow rate calculation unit 133 calculates the flow rate FVO (FV1) based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112.
  • step S108 the process proceeds to step S108 described below.
  • step S104 if the flow rate calculation unit 133 calculates the flow rate FVO (TA1) based only on the TA1 output that is the detection value of the temperature detection unit 111, the TA1 output becomes unstable due to the temperature change of the fluid. In preparation for this, the flow rate calculation unit 133 also calculates the flow rate FVO (FV1) based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. When the process of step S104 ends, the process proceeds to step S105.
  • FVO flow rate
  • step S105 it is determined whether or not the fluid flow rate belongs to region B.
  • the process proceeds to step S107.
  • the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 and the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 are calculated. It is determined whether the deviation from the calculated flow rate FVO (FV1) is equal to or more than the threshold value 1.
  • step S108 when the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is determined to be equal to or greater than the threshold value 1, it is determined that the TA1 output is unstable due to the rapid change in the fluid temperature. , And proceeds to step S108. On the other hand, if it is determined that the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is less than the threshold value 1, it is determined that the TA1 output is stable, and the process proceeds to step S109.
  • step S106 based on the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 and the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. It is determined whether or not the deviation from the calculated flow rate FVO (FV1) is greater than or equal to the threshold value 2.
  • step S108 when it is determined that the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is equal to or greater than the threshold value 2, it is determined that the TA1 output is unstable due to the rapid change in the fluid temperature. , And proceeds to step S108. On the other hand, if it is determined that the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is less than the threshold value 2, it is determined that the TA1 output is stable, and the process proceeds to step S109.
  • step S105 a positive determination is made and a negative determination is made. Since the flow rate region to which the flow rate of the fluid belongs is different, it is assumed that the threshold value that can be used to determine whether or not the TA1 output is unstable is different, and the different threshold values are used in the processing of step S106 and the processing of step S107. Is used.
  • the threshold 1 and the threshold 2 correspond to the predetermined values of the present invention.
  • step S108 the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 is output.
  • step S109 the flow rate FVO (FV1) calculated based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 is output.
  • this routine ends once.
  • the flow rate FVO (calculated only based on the TA1 output of the temperature detection unit 111) TA1) is output.
  • the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 and the difference FV1 between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112.
  • the deviation from the flow rate FVO (FV1) calculated based on the output is equal to or more than the threshold value, it is calculated based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112.
  • the flow rate FVO (FV1) is output.
  • steps S103 and S104 in the flow rate measurement routine 1 correspond to the first flow rate calculation step in the present invention.
  • Step S102 corresponds to the second flow rate calculating step in the present invention.
  • S108 and S109 correspond to the output step in the present invention.
  • FIG. 13 shows an example of changes in the output of the flow rate measuring device 1 when the control in this embodiment is performed.
  • the flow rate of the fluid belongs to the region of medium flow rate to high flow rate.
  • the horizontal axis of FIG. 13 is time, and the vertical axis is the error of the output value by the flow rate measuring device 1 (error from the true flow rate value) and the fluid temperature.
  • the fluid temperature is stable in the time zone of less than 1 hour.
  • the flow rate measuring device 1 outputs the flow rate FVO (TA1) as an output, and sufficiently accurate measurement is performed.
  • the error value of the flow rate FVO (TA1) changes rapidly and falls below -20%.
  • the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) becomes greater than or equal to the threshold value, and the output of the flow rate measuring device 1 is switched from FVO (TA1) to FVO (FV1).
  • the value of the error is recovered to a value that is about the deviation between FVO (FV1) and FVO (TA1).
  • the value of the flow rate FVO (TA1) is extremely reduced and unstable as indicated by a thin broken line in the figure.
  • Example 2 Next, a second embodiment of the present invention will be described.
  • the capacity of the memory that the flow rate measurement device 1 should have can be reduced as much as possible in carrying out the present invention.
  • the flow rate FVO (TA1) when the flow rate FVO (TA1) is calculated from the TA1 output of the temperature detection unit 111, or when the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 is FV1.
  • the values of the TA1 output and the FV1 output were corrected and calculated using the conversion data. Therefore, it is necessary to prepare a conversion data table for a plurality of gas temperatures for correcting the values of the TA1 output and the FV1 output to the flow rate FVO (TA1) and the flow rate FVO (FV1).
  • FIG. 14 shows an example of a correction calculation using a conversion data table that has been conventionally used.
  • FIG. 14 shows a correction calculation when calculating the flow rate FVO (FV1) from the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112.
  • the curve (1) shows the relationship between the FV1 output and the flow rate.
  • an offset is added to the curve of (1) to convert it into a curve (2) that passes through the origin, and further it is multiplied by a gain to be converted into a highly sensitive curve (3).
  • conversion is performed so that the curve (3) and the output coincide with the straight line (4).
  • conversion data of several hundred points is stored for the flow rate range, and such conversion data is stored for a plurality of types of environmental temperatures and a plurality of types of fluid types.
  • the numerical value of several hundreds of points corresponds to a predetermined number of differences in the present invention.
  • the flow rate FVO (FV1) is acquired by performing a polynomial operation on the FV1 output.
  • This polynomial calculation will be described with reference to FIG.
  • a solid line in FIG. 15 is a curve of the relationship between the FV1 output and the flow rate obtained experimentally.
  • this curve is approximated by a cubic polynomial as in the following equation (2).
  • y ax 3 + bx 2 + cx + d (2) Where a, b, c and d are coefficients.
  • x is the FV1 output value
  • y is the flow rate FVO (FV1) value.
  • the coefficients a, b, c, d are stored for three kinds of environmental temperatures and three kinds of fluids.
  • the memory capacity required for calculating the flow rate FVO (FV1) from the FV1 output can be reduced in each stage, and the device cost can be reduced.
  • conversion is performed so that the relationship between FVO (FV1) or FVO (TA1) and the actual flow rate is approximately linear, but in the present embodiment, the FV1 output and the flow rate are changed.
  • the curve of the relationship between and is approximated by a third-order polynomial, and the linearity is not particularly improved. This is because the case where the control in this embodiment is applied corresponds to an emergency situation, so that reduction of the memory capacity is prioritized.
  • FIG. 16 shows a flowchart of the flow rate measurement routine 2 in this embodiment.
  • the difference between this routine and the flow rate measurement routine 1 described in the first embodiment is that the process of step S202 is replaced by the process of step S102, the process of step S203 is replaced by the process of step S103, and the process of step S104.
  • the point is that the process of step S204 is executed instead of.
  • step S101 when it is determined in step S101 that the fluid flow rate does not belong to the area A, that is, the fluid flow rate belongs to the area B or the area C, the process proceeds to step S202 and TA1 of the temperature detection unit 111 is detected.
  • the flow rate FVO (TA1) is calculated by correcting the output using the correction data table.
  • step S203 When it is determined that the flow rate of the fluid belongs to the region A in step S101, the process proceeds to step S203, and the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 is corrected data.
  • the flow rate FVO (FV1) is calculated by performing a correction calculation using the table.
  • step S204 the flow rate FVO (FV1) is calculated by polynomial calculation of the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. To calculate. Since the processing after step S105 is the same as that of the flow rate measurement routine 1, the description is omitted here. As described above, in the present embodiment, when the flow rate of the fluid belongs to the region of medium flow rate to high flow rate, the TA1 output of the temperature detection unit 111 is corrected and calculated by the correction data table, and the flow rate FVO (TA1 ) Is calculated.
  • the flow rate FVO (FV1) is calculated by performing a polynomial operation on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. Then, by determining whether the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is greater than or equal to a threshold value, it is determined whether the TA1 output is unstable due to the influence of the temperature change of the fluid. .
  • step S203 corresponds to the first correction calculation step in the present invention.
  • step S204 corresponds to the first polynomial calculation step.
  • Step S202 corresponds to the second correction calculation step.
  • a flow rate measuring device (1) for measuring a flow rate of a measurement target fluid flowing through a flow path comprising: A heating unit (113) for heating the fluid to be measured, A plurality of temperature detection units (111, 112) arranged on both sides of the heating unit (113) so as to sandwich the heating unit (113) in the flow direction of the fluid to be measured, and to detect the temperature of the fluid to be measured; A first flow rate calculation unit (136) for calculating the flow rate of the fluid to be measured from the difference between the output values of the temperature detection units (111, 112) arranged on both sides of the heating unit (113); A second flow rate calculation unit (137) for calculating the flow rate of the fluid to be measured from the output value of the temperature detection unit (111) arranged on one side of the heating unit (113); Equipped with When the flow rate of the measurement target fluid
  • the output control unit (135) that outputs the flow rate of the measurement target fluid calculated by the first flow rate calculation unit (136) is A flow measuring device, further comprising: ⁇ Invention 4> A heating unit (113) for heating the fluid to be measured, A plurality of temperature detection units (111, 112) arranged on both sides of the heating unit (113) so as to sandwich the heating unit (113) in the flow direction of the fluid to be measured, and to detect the temperature of the fluid to be measured; A flow rate calculation unit (133) that calculates the flow rate of the fluid to be measured from the output values of the temperature detection units (111, 112); A method for controlling a flow rate measuring device (1), comprising: A first flow rate calculation step (S103, S104) of calculating the flow rate of the fluid to be measured from the difference between the output values of the temperature detection sections (111, 112) arranged on both sides of the heating section (113), A second flow rate calculation step (S102) of calculating the flow rate of
  • Flow rate measuring device 11 Flow rate detection part 111: Temperature detection part 112: Temperature detection part 113: Heating part 12: Physical property value detection part 121: Temperature detection part 122: Temperature detection part 123: Heating part 13: Control part 131: Detection value acquisition unit 132: Characteristic value calculation unit 133: Flow rate calculation unit 135: Output control unit 136: First flow rate calculation unit 136a: First correction calculation unit 136b: First polynomial calculation unit 137: Second flow rate calculation unit 137a: Second correction calculation unit

Abstract

In a flow rate measuring device including a heating unit for heating a fluid, and temperature detecting units for detecting the temperature of the fluid, wherein the heating unit and the temperature detecting units are arranged side by side in the direction of flow of the fluid, flow rate measurement is performed more accurately in a flow rate region from a medium flow rate to a high flow rate, even if a temperature difference arises between the fluid temperature and ambient temperature. If the fluid flow rate satisfies a prescribed condition, the fluid flow rate calculated using an output value of the temperature detecting unit disposed on one side of the heating unit is output. Even if the range of the fluid flow rate satisfies the prescribed condition, if a difference between the fluid flow rate calculated using the output value of the temperature detecting unit disposed on one side of the heating unit, and the fluid flow rate calculated using the difference between the output values of the temperature detecting units disposed on both sides of the heating unit is equal to or greater than a prescribed value, the fluid flow rate calculated using the difference between the output values of the temperature detecting units disposed on both sides of the heating unit is output.

Description

流量測定装置及び、流量測定装置の制御方法Flow rate measuring device and control method of flow rate measuring device
　本発明は、流量測定装置及び、流量測定装置の制御方法に関する。 The present invention relates to a flow rate measuring device and a control method of the flow rate measuring device.
　従来より、ヒータおよびセンサを備え、ヒータの発熱によって生じる温度分布が流体の流れによって変化した度合いをセンサで検知することにより、流体の流速又は流量を算出する測定装置が提案されていた。 Conventionally, there has been proposed a measuring device that includes a heater and a sensor and calculates the flow velocity or the flow rate of the fluid by detecting the degree to which the temperature distribution caused by the heat generation of the heater changes due to the flow of the fluid.
　また、主流路を流れる測定対象流体の流量を検出するための流量検出部と、測定対象流体を加熱する加熱部および測定対象流体の温度を検出する温度検出部を有し、測定対象流体の特性値を取得するための特性値取得部と、特性値取得部によって取得された測定対象流体の特性値を用いて、流量検出部から出力された検出信号に基づいて算出された測定対象流体の流量を補正する流量補正部とを備え、加熱部および温度検出部は、測定対象流体の流れ方向と直交する方向に並んで配置されており、特性値取得部は、加熱部の温度を変化させた前後における、温度検出部により検出された測定対象流体の温度の差により、特性値を取得する、流量測定装置が提案されている（例えば、特許文献１を参照）。 Further, it has a flow rate detection unit for detecting the flow rate of the measurement target fluid flowing through the main flow path, a heating unit for heating the measurement target fluid and a temperature detection unit for detecting the temperature of the measurement target fluid, and the characteristics of the measurement target fluid. The flow rate of the measurement target fluid calculated based on the detection signal output from the flow rate detection unit using the characteristic value acquisition unit for acquiring the value and the characteristic value of the measurement target fluid acquired by the characteristic value acquisition unit The heating unit and the temperature detection unit are arranged side by side in a direction orthogonal to the flow direction of the fluid to be measured, and the characteristic value acquisition unit changes the temperature of the heating unit. There has been proposed a flow rate measuring device that acquires a characteristic value based on a difference in temperature of a fluid to be measured detected by a temperature detection unit before and after (for example, refer to Patent Document 1).
　ここで、上述のような従来の熱式の流量測定装置では、流量検出部についても、測定対象流体を加熱する加熱部および測定対象流体の温度を検出する温度検出部を有し、加熱部および温度検出部は、測定対象流体の流れ方向に並んで配置されている構成がとられていた。しかしながら、このような流量測定装置においては、流体の流量が中流量～大流量の領域に属する場合には、測定誤差が大きくなる場合があった。これに対し、流体の流量が中流量～大流量の領域に属する場合には、加熱部の流れ方向上流側に配置された温度検出部で得られた温度に基づいて流量を測定することで、測定誤差の拡大を抑制できることが実験的に分かっていた。そのため、従来より、流体の流量が中流量～大流量の領域に属する場合には、加熱部の流れ方向上流側に配置された温度検出部で得られた温度に基づいて流量を測定することで測定精度の低下を抑制していた。 Here, in the conventional thermal type flow rate measuring device as described above, the flow rate detection unit also has a heating unit that heats the measurement target fluid and a temperature detection unit that detects the temperature of the measurement target fluid. The temperature detectors are arranged side by side in the flow direction of the fluid to be measured. However, in such a flow rate measuring device, when the flow rate of the fluid belongs to the range of medium flow rate to high flow rate, the measurement error may increase. On the other hand, when the flow rate of the fluid belongs to the range of medium flow rate to high flow rate, by measuring the flow rate based on the temperature obtained by the temperature detection unit arranged on the upstream side in the flow direction of the heating unit, It has been experimentally known that expansion of measurement error can be suppressed. Therefore, conventionally, when the flow rate of the fluid belongs to the region of medium flow rate to high flow rate, the flow rate can be measured based on the temperature obtained by the temperature detection unit arranged on the upstream side in the flow direction of the heating unit. The decrease in measurement accuracy was suppressed.
　しかしながら、この方法で測定精度の低下を抑制した場合においては、測定対象流体の温度が変化し、環境温度（流量測定装置の内部温度を含む）との温度差が生じた場合に、加熱部の流れ方向上流側に配置された温度検出部の出力値が極端に変化してしまう不都合があることが分かってきた。 However, when the decrease in measurement accuracy is suppressed by this method, when the temperature of the fluid to be measured changes and a temperature difference from the ambient temperature (including the internal temperature of the flow rate measuring device) occurs, the heating unit It has been found that there is a disadvantage that the output value of the temperature detection unit arranged on the upstream side in the flow direction changes extremely.
特開２０１７－１２９４７０号公報JP, 2017-129470, A
　本発明は、上記のような状況に鑑みてなされたものであり、その目的は、測定対象流体を加熱する加熱部および測定対象流体の温度を検出する温度検出部を有し、加熱部および温度検出部が、測定対象流体の流れ方向に並んで配置される流量測定装置において、流体温度と環境温度に温度差が生じたような場合であっても、中流量から大流量の流量の領域において、より精度よく、流量測定を行うことが可能な技術を提供することである。 The present invention has been made in view of the above situation, and an object thereof is to have a heating unit that heats a measurement target fluid and a temperature detection unit that detects the temperature of the measurement target fluid, and the heating unit and the temperature. In the flow rate measuring device in which the detection unit is arranged side by side in the flow direction of the fluid to be measured, even if there is a temperature difference between the fluid temperature and the environmental temperature, in the range of medium to large flow rate , It is to provide a technique capable of measuring a flow rate with higher accuracy.
　上記の課題を解決するための本発明は、流路を流れる測定対象流体の流量を測定する流量測定装置であって、
　測定対象流体を加熱する加熱部と、
　前記加熱部の両側に該加熱部を前記測定対象流体の流れ方向に挟んで配置され、前記測定対象流体の温度を検出する複数の温度検出部と、
　前記加熱部の両側に配置された温度検出部の出力値の差分より測定対象流体の流量を算出する第一流量算出部と、
　前記加熱部の片側に配置された温度検出部の出力値より前記測定対象流体の流量を算出する第二流量算出部と、
　を備え、
　前記測定対象流体の流量が所定の条件を満たす場合には、前記第二流量算出部が算出した前記測定対象流体の流量を出力するとともに、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合であっても、前記第一流量算出部が算出した前記測定対象流体の流量と、前記第二流量算出部が算出した前記測定対象流体の流量との間の偏差が所定値以上の場合には、前記第一流量算出部が算出した前記測定対象流体の流量を出力する出力制御部を、
　さらに備えることを特徴とする、流量測定装置である。 The present invention for solving the above problems is a flow rate measuring device for measuring the flow rate of a fluid to be measured flowing through a flow path,
A heating unit for heating the fluid to be measured,
A plurality of temperature detection units arranged on both sides of the heating unit with the heating unit sandwiched in the flow direction of the measurement target fluid, for detecting the temperature of the measurement target fluid,
A first flow rate calculation unit that calculates the flow rate of the fluid to be measured from the difference between the output values of the temperature detection units arranged on both sides of the heating unit,
A second flow rate calculation unit for calculating the flow rate of the fluid to be measured from the output value of the temperature detection unit arranged on one side of the heating unit,
Equipped with
When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated by the second flow rate calculation unit is output, and the range of the flow rate of the measurement target fluid is the predetermined condition. Even when satisfying, the deviation between the flow rate of the measurement target fluid calculated by the first flow rate calculation unit and the flow rate of the measurement target fluid calculated by the second flow rate calculation unit is a predetermined value or more. In this case, an output control unit that outputs the flow rate of the measurement target fluid calculated by the first flow rate calculation unit,
It is a flow measuring device characterized by further comprising.
　すなわち、本発明では、測定対象流体を加熱する加熱部および測定対象流体の温度を検出する温度検出部を有し、温度検出部は、加熱部の両側に該加熱部を測定対象流体の流れ方向に挟んで配置される構成をとる流量測定装置において、測定対象流体の流量が所定の条件を満たす場合には、加熱部の片側に配置された温度検出部の出力値より算出された測定対象流体の流量を出力する。そして、測定対象流体の前記流量の範囲が前記所定の条件を満たす場合であっても、加熱部の片側に配置された温度検出部の出力値より算出された測定対象流体の流量と、加熱部の両側に配置された温度検出部の出力値の差分より算出された測定対象流体の流量との間の偏差が所定値以上の場合には、加熱部の両側に配置された温度検出部の出力値の差分より算出された測定対象流体の流量を出力する。これは、この場合には、流体温度と環境温度との間に温度差が生じ、加熱部の片側に配置された温度検出部の出力値より算出された測定対象流体の流量の精度が低下していると判断できるからである。 That is, in the present invention, the heating unit for heating the measurement target fluid and the temperature detection unit for detecting the temperature of the measurement target fluid are provided, and the temperature detection unit has the heating units on both sides of the heating unit in the flow direction of the measurement target fluid. If the flow rate of the fluid to be measured satisfies a predetermined condition, the fluid to be measured calculated from the output value of the temperature detection unit placed on one side of the heating unit Output the flow rate of. Then, even when the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated from the output value of the temperature detection unit arranged on one side of the heating unit, and the heating unit. If the deviation from the flow rate of the fluid to be measured calculated from the difference between the output values of the temperature detection units located on both sides of the The flow rate of the measurement target fluid calculated from the difference between the values is output. This means that in this case, a temperature difference occurs between the fluid temperature and the ambient temperature, and the accuracy of the flow rate of the fluid to be measured calculated from the output value of the temperature detection unit arranged on one side of the heating unit decreases. This is because it can be determined that
　これによれば、測定対象流体の流量が前記所定の条件を満たす場合であっても、流体温度と環境温度との温度差が生じ、加熱部の片側に配置された温度検出部の出力値より算出された測定対象流体の流量の測定精度が低下するような場合には、加熱部の両側に配置された温度検出部の出力値の差分より算出された測定対象流体の流量を出力することができる。その結果、より多様な測定環境において、実用に耐えうる測定精度を維持可能な流量測定装置を実現できる。 According to this, even when the flow rate of the fluid to be measured satisfies the predetermined condition, a temperature difference between the fluid temperature and the environmental temperature is generated, and the output value of the temperature detection unit arranged on one side of the heating unit is used. If the measurement accuracy of the calculated flow rate of the fluid to be measured decreases, it is possible to output the flow rate of the fluid to be measured calculated from the difference between the output values of the temperature detection units located on both sides of the heating unit. it can. As a result, it is possible to realize a flow rate measuring device that can maintain the measurement accuracy that can withstand practical use in a wider variety of measurement environments.
　また、本発明においては、前記所定の条件は、前記流量が所定の中流量～大流量の領域に属することであってもよい。工業規格（例えば、ＥＮ１４２３６）では、流量測定装置に求められる精度が、所定流量値（例えば、５～１０Ｌ／ｍｉｎ）以上で厳しくなるように定められているところ、中流量～大流量は、この工業規格における要求精度が高められる所定流量値（例えば、５～１０Ｌ／ｍｉｎ）以上としてもよい。この条件では、流体温度が安定しており、流体温度と環境温度の温度差が小さい限り、加熱部の両側に配置された温度検出部の出力値の差分より測定対象流体の流量を算出させるよりも、加熱部の片側に配置された温度検出部の出力値より測定対象流体の流量を算出させる方が高精度な測定が可能である点が分かっている。従って、これによれば、流体温度が安定している限り、高精度な流量測定が可能となる。 Further, in the present invention, the predetermined condition may be that the flow rate belongs to a predetermined medium to large flow rate region. According to the industrial standard (for example, EN14236), the accuracy required for the flow rate measuring device is set to be severe at a predetermined flow rate value (for example, 5 to 10 L / min) or more. It may be a predetermined flow rate value (for example, 5 to 10 L / min) or more at which the required accuracy in the industrial standard is improved. Under this condition, as long as the fluid temperature is stable and the temperature difference between the fluid temperature and the ambient temperature is small, the flow rate of the fluid to be measured can be calculated from the difference between the output values of the temperature detection units arranged on both sides of the heating unit. Also, it is known that highly accurate measurement can be performed by calculating the flow rate of the fluid to be measured from the output value of the temperature detection unit arranged on one side of the heating unit. Therefore, according to this, as long as the fluid temperature is stable, highly accurate flow rate measurement becomes possible.
　また、本発明においては、
　前記第一流量算出部は、
　前記加熱部の両側に配置された温度検出部の出力値の差分を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第一補正演算部と、
　前記加熱部の両側に配置された温度検出部の出力値の差分を、多項式演算することで、流量を算出する第一多項式演算部と、を有し、
　前記第二流量算出部は、
　前記加熱部の片側に配置された温度検出部の出力値を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第二補正演算部を有し、
　前記出力制御部は、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合において、前記第一流量算出部が前記第一多項式演算部によって算出した前記測定対象流体の流量と、前記第二流量算出部が前記第二補正演算部によって算出した前記測定対象流体の流量との間の偏差が前記所定値以上の場合には、前記第一流量算出部が算出した前記測定対象流体の流量を出力するようにしてもよい。 Further, in the present invention,
The first flow rate calculation unit,
The difference between the output values of the temperature detection units arranged on both sides of the heating unit is corrected and calculated by using a conversion data table including conversion data set corresponding to a predetermined number of difference values, thereby determining the flow rate. A first correction calculation unit for calculating,
A difference between the output values of the temperature detection units arranged on both sides of the heating unit, a first polynomial calculation unit for calculating a flow rate by performing a polynomial calculation,
The second flow rate calculation unit,
The flow rate is calculated by correcting the output value of the temperature detecting unit arranged on one side of the heating unit using a conversion data table including conversion data set corresponding to a predetermined number of difference values. Has a second correction calculation unit,
The output control unit, when the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated by the first polynomial calculation unit by the first flow rate calculation unit, and When the deviation between the flow rate of the fluid to be measured calculated by the second correction calculation section by the second flow rate calculation section is equal to or more than the predetermined value, the measurement target calculated by the first flow rate calculation section The fluid flow rate may be output.
　ここで、流量測定装置においては、流量を算出する際には、第一流量算出部は第一補正演算部を用いて流量を算出し、第二流量算出部は第二補正演算部を用いて流量を算出することが多い。これは、この補正演算によって、加熱部の両側に配置された温度検出部の出力値の差分あるいは、加熱部の片側に配置された温度検出部の出力値と流体の流量との関係を、原点を通過する直線的な関係に近づけることで、流量測定の精度を向上させるためである。しかし、このような補正演算においては、多数の測定点に対する変換データを格納した変換データテーブルを複数種類記憶しておく必要があり、流量測定装置に必要なメモリの容量を増大させてしまう場合があった。 Here, in the flow rate measuring device, when calculating the flow rate, the first flow rate calculation unit calculates the flow rate using the first correction calculation unit, and the second flow rate calculation unit uses the second correction calculation unit. The flow rate is often calculated. The difference between the output values of the temperature detection units arranged on both sides of the heating unit or the relationship between the output value of the temperature detection unit arranged on one side of the heating unit and the flow rate of the fluid is calculated by this correction calculation. This is to improve the accuracy of flow rate measurement by approaching a linear relationship that passes through. However, in such a correction calculation, it is necessary to store a plurality of types of conversion data tables storing conversion data for a large number of measurement points, which may increase the capacity of the memory required for the flow rate measuring device. there were.
　さらに、本発明のように、測定対象流体の前記流量の範囲が所定の条件を満たす場合であって、加熱部の片側に配置された温度検出部の出力値より算出された流量と、加熱部の両側に配置された温度検出部の出力値の差分より算出された流量との偏差が所定値以上という状況では、流体温度と環境温度との温度差が生じているので、上記の変換データテーブルをそのまま用いることができず、専用の変換データテーブルをさらに記憶しておく必要がある。 Further, as in the present invention, when the range of the flow rate of the fluid to be measured satisfies a predetermined condition, the flow rate calculated from the output value of the temperature detection unit arranged on one side of the heating unit, and the heating unit. In the situation where the deviation from the flow rate calculated from the difference between the output values of the temperature detectors arranged on both sides of the temperature difference is equal to or greater than a predetermined value, there is a temperature difference between the fluid temperature and the environmental temperature. Cannot be used as it is, and it is necessary to further store a dedicated conversion data table.
　これに対し、本発明においては、上記の状況においては、加熱部の両側に配置された温度検出部の出力値の差分を多項式演算することで流量を算出することとした。これによれば、演算に使用する多項式の係数に相当するデータを記憶しておけば変換が可能で、補正演算する場合と比較して必要なメモリ容量を低減することが可能である。その結果、流量測定装置をより簡素化し、あるいはコストをより低減することが可能となる。 On the other hand, in the present invention, in the above situation, the flow rate is calculated by performing a polynomial operation on the difference between the output values of the temperature detection units arranged on both sides of the heating unit. According to this, conversion can be performed by storing the data corresponding to the coefficient of the polynomial used for the calculation, and the required memory capacity can be reduced as compared with the case of performing the correction calculation. As a result, the flow rate measuring device can be further simplified or the cost can be further reduced.
　また、本発明は、測定対象流体を加熱する加熱部と、
　前記加熱部の両側に該加熱部を前記測定対象流体の流れ方向に挟んで配置され、前記測定対象流体の温度を検出する複数の温度検出部と、
　前記温度検出部の出力値より測定対象流体の流量を算出する流量算出部と、
　を備え、流路を流れる測定対象流体の流量を検出する流量測定装置の制御方法であって、
　前記加熱部の両側に配置された温度検出部の出力値の差分より測定対象流体の流量を算出する第一流量算出ステップと、
　前記加熱部の片側に配置された温度検出部の出力値より前記測定対象流体の流量を算出する第二流量算出ステップと、
　前記測定対象流体の流量が所定の条件を満たす場合には、前記第二流量算出ステップにより算出された前記測定対象流体の流量を出力するとともに、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合であっても、前記第一流量算出ステップにおいて算出した前記測定対象流体の流量と、前記第二流量算出ステップにおいて算出した前記測定対象流体の流量との間の偏差が所定値以上の場合には、前記第一流量算出ステップにおいて算出した前記測定対象流体の流量を出力する出力ステップと、
　を有することを特徴とする、流量測定装置の制御方法であってもよい。 Further, the present invention, a heating unit for heating the fluid to be measured,
A plurality of temperature detection units arranged on both sides of the heating unit with the heating unit sandwiched in the flow direction of the measurement target fluid, for detecting the temperature of the measurement target fluid,
A flow rate calculation unit that calculates the flow rate of the fluid to be measured from the output value of the temperature detection unit,
A method of controlling a flow rate measuring device, comprising:
A first flow rate calculating step of calculating the flow rate of the fluid to be measured from the difference between the output values of the temperature detecting sections arranged on both sides of the heating section,
A second flow rate calculating step of calculating the flow rate of the fluid to be measured from the output value of the temperature detecting section arranged on one side of the heating section,
When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated in the second flow rate calculation step is output, and the range of the flow rate of the measurement target fluid is the predetermined range. Even when the condition is satisfied, the deviation between the flow rate of the measurement target fluid calculated in the first flow rate calculation step and the flow rate of the measurement target fluid calculated in the second flow rate calculation step is equal to or more than a predetermined value. In the case of, an output step of outputting the flow rate of the measurement target fluid calculated in the first flow rate calculation step,
The control method of the flow rate measuring device may be characterized by including the following.
　また、本発明は、前記所定の条件は、前記流量が所定の中流量～大流量の領域に属することであることを特徴とする、上記の流量測定装置の制御方法であってもよい。 The present invention may be the control method of the above flow rate measuring device, wherein the predetermined condition is that the flow rate belongs to a predetermined medium flow rate to high flow rate region.
　また、本発明は、前記第一流量算出ステップは、
　前記加熱部の両側に配置された温度検出部の出力値の差分を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第一補正演算工程と、
　前記加熱部の両側に配置された温度検出部の出力値の差分を、多項式演算することで、流量を算出する第一多項式演算工程と、を選択可能に有し、
　前記第二流量算出ステップは、
　前記加熱部の片側に配置された温度検出部の出力値を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第二補正演算工程を有し、
　前記出力ステップでは、
　前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合において、前記第一流量算出ステップにおいて前記第一多項式演算工程によって算出した前記測定対象流体の流量と、前記第二流量算出ステップにおいて前記第二補正演算工程によって算出した前記測定対象流体の流量との間の偏差が前記所定値以上の場合には、前記第一流量算出ステップにおいて前記第一多項式演算工程によって算出した前記測定対象流体の流量を出力することを特徴とする、上記の流量測定装置の制御方法であってもよい。 In the present invention, the first flow rate calculation step is
The difference between the output values of the temperature detection units arranged on both sides of the heating unit is corrected and calculated by using a conversion data table including conversion data set corresponding to a predetermined number of difference values, thereby determining the flow rate. A first correction calculation step for calculating,
The difference between the output values of the temperature detection units arranged on both sides of the heating unit, by performing a polynomial calculation, a first polynomial calculation step of calculating the flow rate, and having a selectable,
The second flow rate calculation step,
The flow rate is calculated by correcting the output value of the temperature detecting unit arranged on one side of the heating unit using a conversion data table including conversion data set corresponding to a predetermined number of difference values. Has a second correction calculation step,
In the output step,
When the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated by the first polynomial calculation step in the first flow rate calculation step, and the second flow rate calculation If the deviation from the flow rate of the fluid to be measured calculated in the second correction calculation step in the step is not less than the predetermined value, it is calculated in the first polynomial calculation step in the first flow rate calculation step. The control method of the above flow rate measuring device may be characterized in that the flow rate of the fluid to be measured is output.
　なお、本発明における上記の課題を解決するための手段は、可能な限り組み合わせて使用することが可能である。 The means for solving the above problems in the present invention can be used in combination as much as possible.
　本発明によれば、測定対象流体を加熱する加熱部および測定対象流体の温度を検出する温度検出部を有し、加熱部および温度検出部が、測定対象流体の流れ方向に並んで配置される流量測定装置において、流体温度と環境温度に温度差が生じたような場合であっても、中流量から大流量の流量の領域において、より精度よく、流量測定を行うことが可能となる。その結果、より多様な測定環境において、実用に耐えうる測定精度を維持可能な流量測定装置を実現することができる。 According to the present invention, the heating unit for heating the measurement target fluid and the temperature detection unit for detecting the temperature of the measurement target fluid are provided, and the heating unit and the temperature detection unit are arranged side by side in the flow direction of the measurement target fluid. In the flow rate measuring device, even when there is a temperature difference between the fluid temperature and the environmental temperature, the flow rate can be measured with higher accuracy in the range of medium flow rate to high flow rate. As a result, it is possible to realize a flow rate measuring device capable of maintaining measurement accuracy that can be practically used in a wider variety of measurement environments.
本発明の実施例における流量測定装置の一例を示す分解斜視図である。It is an exploded perspective view showing an example of a flow measuring device in an example of the present invention. 本発明の実施例における流量測定装置の一例を示す断面図である。It is sectional drawing which shows an example of the flow measuring device in the Example of this invention. 本発明の実施例における副流路部を示す平面図である。It is a top view which shows the sub flow path part in the Example of this invention. 本発明の実施例におけるセンサ素子の一例を示す斜視図である。It is a perspective view which shows an example of the sensor element in the Example of this invention. 本発明の実施例におけるセンサ素子の仕組みを説明するための断面図である。It is sectional drawing for demonstrating the mechanism of the sensor element in the Example of this invention. 本発明の実施例における流量検出部の概略構成を示す平面図である。It is a top view which shows schematic structure of the flow volume detection part in the Example of this invention. 本発明の実施例における物性値検出部の概略構成を示平面図である。It is a top view showing a schematic structure of a physical property value detecting part in an example of the present invention. 本発明の実施例における流量測定装置の機能構成を示すブロック図である。It is a block diagram which shows the function structure of the flow measuring device in the Example of this invention. 本発明の実施例における流量算出部の詳細な機能構成を示すブロック図である。It is a block diagram which shows the detailed functional structure of the flow volume calculation part in the Example of this invention. 各温度検出部の温度検出値の挙動を示すグラフである。It is a graph which shows the behavior of the temperature detection value of each temperature detection part. 本発明の実施例において、流体の温度が急激に変化した場合の、片側の温度検出部の出力の変化について示す図である。FIG. 6 is a diagram showing a change in output of a temperature detection unit on one side when a fluid temperature changes abruptly in an example of the present invention. 本発明の実施例１における、流量測定ルーチン１の制御内容を示すフローチャートである。3 is a flowchart showing the control contents of a flow rate measurement routine 1 in the first embodiment of the present invention. 本発明の実施例１における流量測定装置の出力例を示すグラフである。It is a graph which shows the output example of the flow measuring device in Example 1 of the present invention. 本発明の実施例２における、温度検出部の出力の補正演算を説明するための図である。FIG. 7 is a diagram for explaining correction calculation of an output of the temperature detection unit in the second embodiment of the present invention. 本発明の実施例２における、温度検出部の出力の多項式演算を説明するための図である。FIG. 9 is a diagram for explaining polynomial calculation of an output of the temperature detection unit in the second embodiment of the present invention. 本発明の実施例２における、流量測定ルーチン２の制御内容を示すフローチャートである。6 is a flowchart showing the control contents of a flow rate measurement routine 2 in Example 2 of the present invention.
〔適用例〕
　以下、本発明の適用例について、図面を参照しつつ説明する。本発明は例えば、図１に示すような熱式の流量測定装置１に適用される。流量測定装置１は、例えばガスメータや燃焼機器、自動車等の内燃機関、燃料電池、その他医療等の産業機器、組込機器に組み込まれ、流路を通過する流体の量を測定する。流量測定装置１は、図２に示すように、主流路部２を流れる流体を分流し、その一部を流量検出部１１に導いて、主流路部２の流体の流量と高い相関を有する、流量検出部１１における流量を測定するものである。流量検出部１１に用いられるセンサ素子は、図４に示すように、マイクロヒータ（加熱部）１０１を挟んで二つのサーモパイル１０２が配置された構成を有する。測定原理としては、図５に示すように、二つのサーモパイル１０２で検出される温度の検出値の差分と、その上を通過する流体の流量との間の相関関係を利用したものである。 [Application example]
Hereinafter, application examples of the present invention will be described with reference to the drawings. The present invention is applied to, for example, a thermal type flow rate measuring device 1 as shown in FIG. The flow rate measuring device 1 is installed in, for example, a gas meter, a combustion device, an internal combustion engine such as an automobile, a fuel cell, other industrial devices such as medical equipment, and a built-in device, and measures the amount of fluid passing through the flow path. As shown in FIG. 2, the flow rate measuring device 1 diverts the fluid flowing through the main flow path portion 2 and guides a part of the fluid to the flow rate detecting portion 11, which has a high correlation with the flow rate of the fluid in the main flow path portion 2. The flow rate in the flow rate detector 11 is measured. As shown in FIG. 4, the sensor element used in the flow rate detection unit 11 has a configuration in which two thermopiles 102 are arranged with a microheater (heating unit) 101 interposed therebetween. As the measurement principle, as shown in FIG. 5, the correlation between the difference between the detected temperature values detected by the two thermopiles 102 and the flow rate of the fluid passing therethrough is used.
　また、流量測定装置１の機能ブロック図８に示すように、流量検出部１１の出力は、回路基板５に配置されたＣＰＵ（Central Processing Unit）により実現される制御部１３の検出値取得部１３１に送信され、流量算出部１３３において最終的な出力としての流量が算出される。なお、回路基板５には、ＣＰＵの他、制御部１３の機能を実現するための記憶部（メモリ：不図示）も配置されている。 Further, as shown in the functional block diagram 8 of the flow rate measurement device 1, the output of the flow rate detection unit 11 is the detection value acquisition unit 131 of the control unit 13 realized by the CPU (Central Processing Unit) arranged on the circuit board 5. And the flow rate calculation unit 133 calculates the flow rate as the final output. In addition to the CPU, a storage unit (memory: not shown) for realizing the functions of the control unit 13 is also arranged on the circuit board 5.
　本適用例は、上述のような流量測定装置１の制御に関する。本適用例では、流体の流量が図１０に示す領域Ｂまたは領域Ｃに属する場合には、マイクロヒータ１０１の上流側に配置されたサーモパイル１０２（温度検出部１１１）の出力値より算出された流体の流量を出力することを前提としている。これは、上記の条件では、マイクロヒータ１０１の両側に配置されたサーモパイル１０２（温度検出部１１１、１１２）の出力値の差分より算出された流体の流量の精度が低下することが分かっているからである。 This application example relates to control of the flow rate measuring device 1 as described above. In this application example, when the flow rate of the fluid belongs to the region B or the region C shown in FIG. 10, the fluid calculated from the output value of the thermopile 102 (temperature detection unit 111) arranged on the upstream side of the microheater 101. It is assumed that the flow rate of is output. This is because it is known that under the above conditions, the accuracy of the fluid flow rate calculated from the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the microheater 101 decreases. Is.
　そして、本適用例では、流体の流量が図１０に示す領域Ｂまたは領域Ｃに属する場合であっても、マイクロヒータ１０１の上流側に配置されたサーモパイル１０２（温度検出部１１１）の出力値より算出された測定対象流体の流量と、マイクロヒータ１０１の両側に配置されたサーモパイル１０２（温度検出部１１１、１１２）の出力値の差分より算出された測定対象流体の流量との間の偏差が所定値以上の場合には、マイクロヒータ１０１の両側に配置されたサーモパイル１０２（温度検出部１１１、１１２）の出力値の差分より算出された測定対象流体の流量を出力する。これは、この場合には、流体温度と環境温度との間に温度差が生じており、図１１（ｂ）に示す様に、マイクロヒータ１０１の上流側に配置されたサーモパイル１０２（温度検出部１１１）の出力値より算出された測定対象流体の流量の精度が著しく低下していると判断できるからである。 Then, in this application example, even when the flow rate of the fluid belongs to the region B or the region C shown in FIG. 10, the output value of the thermopile 102 (temperature detection unit 111) arranged on the upstream side of the microheater 101 The deviation between the calculated flow rate of the measurement target fluid and the flow rate of the measurement target fluid calculated from the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the micro-heater 101 is predetermined. When the value is equal to or larger than the value, the flow rate of the fluid to be measured calculated based on the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the microheater 101 is output. In this case, there is a temperature difference between the fluid temperature and the environmental temperature, and as shown in FIG. 11B, the thermopile 102 (temperature detecting unit) arranged upstream of the micro heater 101 is used. This is because it can be determined that the accuracy of the flow rate of the fluid to be measured calculated from the output value of (111) has significantly decreased.
　これによれば、流量が領域Ｂまたは領域Ｃに属するような場合であっても、流体温度と環境温度との温度差が生じ、マイクロヒータ１０１の上流側に配置されたサーモパイル１０２（温度検出部１１１）の出力値より算出された測定対象流体の流量の測定精度が低下するような場合には、マイクロヒータ１０１の両側に配置されたサーモパイル１０２（温度検出部１１１、１１２）の出力値の差分より算出された測定対象流体の流量を出力することができる。その結果、より多様な測定環境において、流量測定装置１の測定精度を維持することが可能となる。 According to this, even when the flow rate belongs to the region B or the region C, a temperature difference between the fluid temperature and the environmental temperature is generated, and the thermopile 102 (temperature detection unit disposed on the upstream side of the microheater 101). When the measurement accuracy of the flow rate of the measurement target fluid calculated from the output value of 111) decreases, the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the microheater 101. The calculated flow rate of the fluid to be measured can be output. As a result, the measurement accuracy of the flow rate measuring device 1 can be maintained in a wider variety of measurement environments.
　なお、流量測定装置１において流量を算出する際には、例えば、マイクロヒータ１０１の両側に配置されたサーモパイル１０２（温度検出部１１１、１１２）の出力値の差分に、図１４に示したような補正を行う補正演算を行うことで流量を算出する。これは、この補正演算によって、流量測定装置１の出力と流量との関係を、図１４の（４）のラインに示すような、原点を通過する直線的な関係に近づけるためである。しかし、このような補正演算においては、図１４の横軸に対して数百ポイントに上る変換データを格納した変換データテーブルを複数記憶しておく必要があり、流量測定装置１のメモリ容量を増大させてしまう場合があった。さらに、本適用例のように、図１１に示したように、流体の温度が急激に変化するような状況で、上記のような補正演算を行うためには、専用の変換データテーブルをさらに記憶しておく必要がある。 When calculating the flow rate in the flow rate measuring device 1, for example, the difference between the output values of the thermopiles 102 (temperature detecting units 111 and 112) arranged on both sides of the micro-heater 101 is as shown in FIG. The flow rate is calculated by performing a correction calculation to perform the correction. This is because the correction calculation brings the relationship between the output of the flow rate measuring device 1 and the flow rate close to the linear relationship passing through the origin, as shown by the line (4) in FIG. However, in such a correction calculation, it is necessary to store a plurality of conversion data tables storing conversion data of several hundred points on the horizontal axis of FIG. 14, which increases the memory capacity of the flow rate measuring device 1. There was a case to let it. Further, as in the present application example, as shown in FIG. 11, in order to perform the correction calculation as described above in a situation where the temperature of the fluid changes rapidly, a dedicated conversion data table is further stored. You need to do it.
　これに対し、本適用例では、マイクロヒータ１０１の両側に配置されたサーモパイル１０２（温度検出部１１１、１１２）の出力値の差分を図１５に示すような多項式演算することで流量を算出することとした。これによれば、演算に使用する多項式の係数ａ、ｂ、ｃ、ｄに相当するデータを記憶しておくことで、補正演算する場合と比較して必要なメモリ容量を低減することが可能となる。 On the other hand, in this application example, the flow rate is calculated by performing a polynomial calculation as shown in FIG. 15 on the difference between the output values of the thermopiles 102 (temperature detection units 111 and 112) arranged on both sides of the microheater 101. And According to this, by storing the data corresponding to the coefficients a, b, c, and d of the polynomial used for the calculation, it is possible to reduce the required memory capacity as compared with the case where the correction calculation is performed. Become.
〔実施例１〕
　以下では、本発明の実施例に係る流量測定装置について、図面を用いて、より詳細に説明する。 [Example 1]
Hereinafter, a flow rate measuring device according to an embodiment of the present invention will be described in more detail with reference to the drawings.
＜装置構成＞
　図１は、本実施例に係る流量測定装置１の一例を示す分解斜視図である。図２は、流量測定装置１の一例を示す断面図である。なお、図１及び図２の破線の矢印は、流体の流れる方向を例示している。図１に示すように、本実施例に係る流量測定装置１は、主流路部２と、副流路部３と、シール４と、回路基板５と、カバー６とを備えている。図１及び図２に示すように、本実施例では、流量測定装置１は主流路部２から分岐した副流路部３を有する。また副流路部３には、流量検出部１１と、物性値検出部１２が備えられる。流量検出部１１及び物性値検出部１２は、マイクロヒータによって形成される加熱部とサーモパイルによって形成される温度検出部とを含む熱式のフローセンサによって構成されている。また、本実施例では、物性値検出部１２を利用して流体の物性値を検出し、流量検出部１１によって検出される流量を流体の物性値に基づいて補正するものとするが、流量測定装置１は、必ずしも物性値検出部１２を備えていなくてもよい。 <Device configuration>
FIG. 1 is an exploded perspective view showing an example of a flow rate measuring device 1 according to this embodiment. FIG. 2 is a sectional view showing an example of the flow rate measuring device 1. The broken line arrows in FIGS. 1 and 2 exemplify the direction in which the fluid flows. As shown in FIG. 1, the flow rate measuring device 1 according to the present embodiment includes a main flow path portion 2, a sub flow path portion 3, a seal 4, a circuit board 5, and a cover 6. As shown in FIG. 1 and FIG. 2, in this embodiment, the flow rate measuring device 1 has a sub-flow passage section 3 branched from the main flow passage section 2. In addition, the sub-flow path unit 3 is provided with a flow rate detection unit 11 and a physical property value detection unit 12. The flow rate detecting unit 11 and the physical property value detecting unit 12 are configured by a thermal type flow sensor including a heating unit formed by a micro heater and a temperature detecting unit formed by a thermopile. Further, in the present embodiment, the physical property value of the fluid is detected by using the physical property value detection unit 12, and the flow rate detected by the flow rate detection unit 11 is corrected based on the physical property value of the fluid. The device 1 does not necessarily have to include the physical property value detection unit 12.
　主流路部２は、測定対象である流体の流路（以下、主流路ともいう）が長手方向に貫通した管状の部材である。図２に示すように、主流路部２の内周面には、流体の流れ方向に対して、上流側に流入口（第１流入口）３４Ａが形成され、下流側に流出口（第１流出口）３５Ａが形成されている。例えば主流路部２の軸方向の長さは約５０ｍｍであり、内周面の直径（主流路部２の内径）は約２０ｍｍであり、主流路部２の外径は約２４ｍｍであるが、主流路部２の寸法はこれらに限定されない。また、主流路部２には、流入口３４Ａと流出口３５Ａとの間にオリフィス２１が設けられている。オリフィス２１は、主流路部２においてその前後よりも内径が小さくなった抵抗体であり、オリフィス２１の大きさによって副流路部３へ流入する流体の量を調整することができる。 The main flow path part 2 is a tubular member through which a flow path of a fluid to be measured (hereinafter, also referred to as a main flow path) penetrates in the longitudinal direction. As shown in FIG. 2, an inlet (first inlet) 34A is formed on the upstream side and an outlet (first inlet) on the downstream side in the inner peripheral surface of the main flow path portion 2 in the flow direction of the fluid. Outflow port) 35A is formed. For example, the length of the main flow path portion 2 in the axial direction is about 50 mm, the diameter of the inner peripheral surface (inner diameter of the main flow path portion 2) is about 20 mm, and the outer diameter of the main flow path portion 2 is about 24 mm. The dimensions of the main flow path portion 2 are not limited to these. Further, in the main flow path portion 2, the orifice 21 is provided between the inflow port 34A and the outflow port 35A. The orifice 21 is a resistor having an inner diameter smaller than that in the front and the rear of the main flow path portion 2, and the amount of fluid flowing into the sub flow path portion 3 can be adjusted by the size of the orifice 21.
　図１及び図２においては、主流路から分岐した副流路を内部に含む部分である副流路部３は主流路部２の鉛直上方に設けられている。また、副流路部３内の副流路は、流入用流路３４と、物性値検出用流路３２と、流量検出用流路３３と、流出用流路３５とを含む。副流路部３には、主流路部２を流れる流体の一部が分岐して流入する。 In FIGS. 1 and 2, the sub-flow passage portion 3 which is a portion including the sub-flow passage branched from the main flow passage therein is provided above the main flow passage portion 2 in the vertical direction. Further, the sub-flow paths in the sub-flow path portion 3 include an inflow flow path 34, a physical property value detection flow path 32, a flow rate detection flow path 33, and an outflow flow path 35. A part of the fluid flowing through the main flow path portion 2 branches into the sub flow path portion 3 and flows into the sub flow path portion 3.
　流入用流路３４は、主流路部２を流れる流体を流入させて、物性値検出用流路３２および流量検出用流路３３に分流させるための流路である。流入用流路３４は、主流路部２における流体の流れ方向と垂直な方向に沿って形成されており、一端が流入口３４Ａに接続され、他端は物性値検出用流路３２および流量検出用流路３３に接続されている。主流路部２を流れる流体の一部は、流入用流路３４を介して、さらに物性値検出用流路３２および流量検出用流路３３に分流する。このような物性値検出用流路３２及び流量検出用流路３３には、主流路部２を流れる流体の量に応じた量の流体が流入する。したがって、流量検出部１１は、主流路部２を流れる流体の量に応じた値を検出することができる。 The inflow passage 34 is a passage for inflowing the fluid flowing through the main passage portion 2 and splitting the fluid into the physical property value detecting passage 32 and the flow amount detecting passage 33. The inflow passage 34 is formed along a direction perpendicular to the flow direction of the fluid in the main passage portion 2, one end thereof is connected to the inflow port 34A, and the other end is connected to the physical property value detection passage 32 and the flow amount detection. It is connected to the flow channel 33. A part of the fluid flowing through the main flow path portion 2 is further divided into the physical property value detection flow path 32 and the flow rate detection flow path 33 via the inflow flow path 34. An amount of fluid corresponding to the amount of fluid flowing through the main flow path portion 2 flows into the physical property value detection flow path 32 and the flow rate detection flow path 33. Therefore, the flow rate detection unit 11 can detect a value according to the amount of fluid flowing through the main flow path unit 2.
　図１に示すように、物性値検出用流路３２は、主流路部２の鉛直上方に形成され、主流路部２と平行な方向に延在する、上側から見た断面が略コ字型の流路である。物性値検出用流路３２は、その内部に、測定対象流体の物性値を検出するための物性値検出部１２が配置されている。物性値検出用流路３２の一端は、流入用流路３４に接続されており、他端は、流出用流路３５接続されている。 As shown in FIG. 1, the physical property value detection flow channel 32 is formed vertically above the main flow channel portion 2, extends in a direction parallel to the main flow channel portion 2, and has a substantially U-shaped cross section when viewed from above. Is the flow path. The physical property value detection flow path 32 has therein the physical property value detection unit 12 for detecting the physical property value of the fluid to be measured. One end of the physical property value detection flow path 32 is connected to the inflow flow path 34, and the other end is connected to the outflow flow path 35.
　流量検出用流路３３も、主流路部２における流体の流れ方向と平行な方向に延在する、上側から見た断面が略コの字型の流路である。流量検出用流路３３には、その内部に、流体の流量を検出するための流量検出部１１が配置されている。また、流量検出用流路３３の一端は、流入用流路３４に接続されており、他端は、流出用流路３５に接続されている。なお、物性値検出部１２、流量検出部１１は、それぞれ回路基板５上に実装される。そして、回路基板５は、上部が開放された物性値検出用流路３２、流量検出用流路３３の上部を覆うと共に、物性値検出用流路３２に物性値検出部１２が位置し、流量検出用流路３３に流量検出部１１が位置するように配置される。 The flow rate detecting flow path 33 is also a flow path that extends in a direction parallel to the flow direction of the fluid in the main flow path portion 2 and has a substantially U-shaped cross section as viewed from above. The flow rate detection flow path 33 has therein a flow rate detection unit 11 for detecting the flow rate of the fluid. Further, one end of the flow rate detection flow path 33 is connected to the inflow flow path 34, and the other end is connected to the outflow flow path 35. The physical property value detector 12 and the flow rate detector 11 are mounted on the circuit board 5, respectively. Then, the circuit board 5 covers the upper portions of the physical property value detection flow channel 32 and the flow rate detection flow channel 33, which are open at the top, and the physical property value detection unit 12 is located in the physical property value detection flow channel 32. The flow rate detection unit 11 is arranged in the detection flow path 33.
　流出用流路３５は、物性値検出用流路３２および流量検出用流路３３を通過した測定対象流体を、主流路部２に流出させるための流路である。流出用流路３５は、主流路部２と垂直な方向に沿って形成されており、一端が流出口３５Ａに接続され、他端は物性値検出用流路３２および流量検出用流路３３に接続されている。物性値検出用流路３２および流量検出用流路３３を通過した測定対象流体は、流出用流路３５を介して、主流路部２に流出する。 The outflow channel 35 is a channel for allowing the measurement target fluid that has passed through the physical property value detection channel 32 and the flow rate detection channel 33 to flow out to the main channel section 2. The outflow passage 35 is formed along the direction perpendicular to the main flow passage portion 2, one end thereof is connected to the outflow port 35A, and the other end is connected to the physical property value detection passage 32 and the flow amount detection passage 33. It is connected. The measurement target fluid that has passed through the physical property value detection flow path 32 and the flow rate detection flow path 33 flows out to the main flow path unit 2 via the outflow flow path 35.
　本実施例では、上述のように、１つの流入口３４Ａから流入させた測定対象流体を、物性値検出用流路３２および流量検出用流路３３に分流させている。これにより、流量検出部１１および物性値検出部１２は、それぞれ温度、密度などの条件がほぼ等しい流体に基づいて、測定対象の流体の物性値や流量を検出することができる。なお、流量測定装置１は、副流路部３にシール４を嵌め込んだ後、回路基板５が配置され、さらにカバー６によって回路基板５を副流路部３に固定することで、副流路部３の内部の気密性を確保している。 In the present embodiment, as described above, the fluid to be measured, which has flowed in from one inflow port 34A, is split into the physical property value detection flow channel 32 and the flow rate detection flow channel 33. Accordingly, the flow rate detection unit 11 and the physical property value detection unit 12 can detect the physical property value and the flow rate of the fluid to be measured, based on the fluids having substantially the same conditions such as temperature and density. In the flow rate measurement device 1, the circuit board 5 is arranged after the seal 4 is fitted in the sub-flow passage portion 3, and the circuit board 5 is fixed to the sub-flow passage portion 3 by the cover 6, so that the side flow The airtightness of the inside of the road portion 3 is ensured.
　図３は、図１に示される副流路部３の平面図である。図３に示すように、物性値検出用流路３２と流量検出用流路３３とは、流入用流路３４と流出用流路３５を結ぶ線（不図示）に対して対称に配置されている。また、矢印Ｐ及びＱは、物性値検出用流路３２および流量検出用流路３３に分流する流体の流量の比率を模式的に表している。本実施例では、分流される流体の量がＰ対Ｑの割合になるように、物性値検出用流路３２および流量検出用流路３３の断面積が定められている。 FIG. 3 is a plan view of the sub-flow path portion 3 shown in FIG. As shown in FIG. 3, the physical property value detection flow path 32 and the flow rate detection flow path 33 are arranged symmetrically with respect to a line (not shown) connecting the inflow flow path 34 and the outflow flow path 35. There is. Further, arrows P and Q schematically show the ratio of the flow rates of the fluids divided into the physical property value detection flow channel 32 and the flow rate detection flow channel 33. In the present embodiment, the cross-sectional areas of the physical property value detection flow channel 32 and the flow rate detection flow channel 33 are determined such that the amount of the divided fluid is P: Q.
　実際に物性値検出用流路３２および流量検出用流路３３を流れる流体の量は、主流路部２を流れる流体の流量に応じて変動するが、通常の使用態様において、物性値検出用流路３２を流れる流体の量は物性値検出部１２の検出レンジ内の値となり、流量検出用流路３３を流れる流体の量は流量検出部１１の検出レンジ内の値となるように、主流路部２に対する副流路部３の大きさやオリフィス２１の大きさ、物性値検出用流路３２および流量検出用流路３３の幅がそれぞれ設定されている。なお、物性値検出用流路３２及び流量検出用流路３３の幅は例示であり、図３に示す例には限定されない。 The amount of the fluid actually flowing through the physical property value detecting flow path 32 and the flow rate detecting flow path 33 varies depending on the flow rate of the fluid flowing through the main flow path portion 2. The amount of fluid flowing through the passage 32 becomes a value within the detection range of the physical property value detection unit 12, and the amount of fluid flowing through the flow rate detection flow channel 33 becomes a value within the detection range of the flow rate detection unit 11 The size of the sub-flow passage portion 3 with respect to the portion 2 and the size of the orifice 21, and the widths of the physical property value detection flow passage 32 and the flow rate detection flow passage 33 are set. The widths of the physical property value detection flow channel 32 and the flow rate detection flow channel 33 are mere examples, and are not limited to the example shown in FIG.
　以上のように、物性値検出用流路３２および流量検出用流路３３を流れる流体の量は、主流路部２を流れる流体の量よりも少ないが、それぞれ主流路部２を流れる流体の量に応じて変化する。仮に流量検出部１１や物性値検出部１２を主流路部２に配置する場合は、主流路部２を流れる流体の量に応じて流量検出部１１および物性値検出部１２の規模を大きくする必要が生じるが、本実施形態では主流路部２から分岐する副流路部３を設けることにより、規模の小さい流量検出部１１および物性値検出部１２によって流体の流量を測定できるようにしている。 As described above, the amount of fluid flowing through the physical property value detection flow channel 32 and the flow rate detection flow channel 33 is smaller than the amount of fluid flowing through the main flow channel unit 2, but the amount of fluid flowing through each of the main flow channel units 2 is large. Change according to. If the flow rate detection unit 11 and the physical property value detection unit 12 are arranged in the main flow channel unit 2, it is necessary to increase the scales of the flow rate detection unit 11 and the physical property value detection unit 12 according to the amount of fluid flowing through the main flow channel unit 2. However, in the present embodiment, by providing the sub-flow path section 3 that branches from the main flow path section 2, the flow rate of the fluid can be measured by the small-scale flow rate detection section 11 and the physical property value detection section 12.
　図４は、流量検出部１１及び物性値検出部１２に用いられるセンサ素子の一例を示す斜視図である。また、図５は、センサ素子の仕組みを説明するための断面図である。センサ素子１００は、マイクロヒータ（加熱部ともいう）１０１と、マイクロヒータ１０１を挟んで対称に設けられた二つのサーモパイル（温度検出部ともいう）１０２とを備える。すなわち、マイクロヒータ１０１と二つのサーモパイル１０２とは、所定の方向に並ぶように配置されている。これらの上下には、図５に示すように絶縁薄膜１０３が形成され、マイクロヒータ１０１、サーモパイル１０２及び絶縁薄膜１０３はシリコン基台１０４上に設けられている。また、マイクロヒータ１０１及びサーモパイル１０２の下方のシリコン基台１０４には、エッチング等により形成されるキャビティ（空洞）１０５が設けられている。 FIG. 4 is a perspective view showing an example of a sensor element used in the flow rate detection unit 11 and the physical property value detection unit 12. Further, FIG. 5 is a cross-sectional view for explaining the mechanism of the sensor element. The sensor element 100 includes a micro heater (also referred to as a heating unit) 101, and two thermopiles (also referred to as a temperature detection unit) 102 that are symmetrically provided with the micro heater 101 interposed therebetween. That is, the micro-heater 101 and the two thermopiles 102 are arranged so as to be aligned in a predetermined direction. As shown in FIG. 5, an insulating thin film 103 is formed above and below these, and the micro heater 101, the thermopile 102, and the insulating thin film 103 are provided on a silicon base 104. Further, a cavity 105 formed by etching or the like is provided in the silicon base 104 below the micro heater 101 and the thermopile 102.
　マイクロヒータ１０１は、例えばポリシリコンで形成された抵抗である。図５においては、破線の楕円によって、マイクロヒータ１０１が発熱した場合の温度分布を模式的に示している。なお、破線が太いほど温度が高いことを示すものとする。流体の流れがない場合、図５（ａ）に示すようにマイクロヒータ１０１の周囲の温度分布はほぼ均等になる。一方、例えば図５（ｂ）において破線の矢印で示す方向に流体が流れた場合、周囲の空気が移動するため、マイクロヒータ１０１の上流側よりも下流側の方が温度は高くなる。センサ素子１００は、このようなヒータ熱の分布の偏りを利用して、流量を示す値を出力する。 The micro heater 101 is, for example, a resistor formed of polysilicon. In FIG. 5, a dashed ellipse schematically shows the temperature distribution when the microheater 101 generates heat. The thicker the broken line, the higher the temperature. When there is no fluid flow, the temperature distribution around the micro-heater 101 becomes substantially uniform as shown in FIG. On the other hand, for example, when the fluid flows in the direction indicated by the dashed arrow in FIG. 5B, the surrounding air moves, so the temperature becomes higher on the downstream side than on the upstream side of the microheater 101. The sensor element 100 outputs a value indicating the flow rate by utilizing such uneven distribution of the heater heat.
　センサ素子の出力電圧ΔＶは、例えば次のような式（１）で表される。
Figure JPOXMLDOC01-appb-M000001
 　なお、Ｔｈはマイクロヒータ１０１の温度（サーモパイル１０２におけるマイクロヒータ１０１側の端部の温度）、Ｔａはサーモパイル１０２におけるマイクロヒータ１０１から遠い側の端部の温度のうち低い方の温度（図５（ａ）では左側のサーモパイル１０２の左端の温度又は右側のサーモパイル１０２の右端の温度であり、図５（ｂ）では上流側の端部である左側のサーモパイル１０２の左端の温度）、Ｖｆは流速の平均値、Ａ及びｂは所定の定数である。 The output voltage ΔV of the sensor element is expressed by the following equation (1), for example.
Figure JPOXMLDOC01-appb-M000001
 Note that Th is the temperature of the microheater 101 (the temperature of the end of the thermopile 102 on the microheater 101 side), and Ta is the lower temperature of the end of the thermopile 102 on the side far from the microheater 101 (see FIG. In a), the temperature at the left end of the left thermopile 102 or the temperature at the right end of the right thermopile 102, and in FIG. 5B, the temperature at the left end of the left thermopile 102, which is the upstream end), Vf Average values, A and b are predetermined constants.
＜流量検出部及び物性値検出部＞
　図６は、図１に示した流量検出部１１の概略構成を示す平面図であり、図７は、図１に示した物性値検出部１２の概略構成を示す平面図である。図６に示すように、流量検出部１１は、測定対象の流体の温度を検出する第１サーモパイル（温度検出部ともいう）１１１および第２サーモパイル（温度検出部ともいう）１１２と、測定対象流体を加熱するマイクロヒータ（加熱部ともいう）１１３とを備えている。加熱部１１３と、温度検出部１１１および温度検出部１１２とは、流量検出部１１内において、測定対象流体の流れ方向の矢印Ｐに沿って並べて配置されている。また、加熱部１１３、温度検出部１１１、および温度検出部１１２の形状は、平面視においてそれぞれ略矩形であり、各々の長手方向は測定対象流体の流れ方向の矢印Ｐと直交する。 <Flow rate detector and physical property value detector>
FIG. 6 is a plan view showing a schematic configuration of the flow rate detection unit 11 shown in FIG. 1, and FIG. 7 is a plan view showing a schematic configuration of the physical property value detection unit 12 shown in FIG. As shown in FIG. 6, the flow rate detection unit 11 includes a first thermopile (also referred to as a temperature detection unit) 111 and a second thermopile (also referred to as a temperature detection unit) 112 that detect the temperature of a measurement target fluid, and a measurement target fluid. And a micro-heater (also referred to as a heating unit) 113 for heating. The heating unit 113, the temperature detecting unit 111, and the temperature detecting unit 112 are arranged in the flow rate detecting unit 11 side by side along the arrow P in the flow direction of the fluid to be measured. The shapes of the heating unit 113, the temperature detecting unit 111, and the temperature detecting unit 112 are substantially rectangular in plan view, and the longitudinal direction of each is orthogonal to the arrow P of the flow direction of the fluid to be measured.
　温度検出部１１１および温度検出部１１２は、加熱部１１３の上流側に温度検出部１１１が配置され、下流側に温度検出部１１２が配置されて、加熱部１１３を挟んで対称な位置の温度を検出する。流量測定装置１では、流量検出部１１および物性値検出部１２に、実質的に同一構造のセンサ素子１００が用いられており、流体の流れ方向に対する配置角度を、センサ素子１００の平面視上、９０度異ならせて配置されている。これにより、同一構造のセンサ素子１００を流量検出部１１及び物性値検出部１２に使用することができ、流量測定装置１の製造コストを抑制することができる。 In the temperature detection unit 111 and the temperature detection unit 112, the temperature detection unit 111 is arranged on the upstream side of the heating unit 113, and the temperature detection unit 112 is arranged on the downstream side, so that the temperature at symmetrical positions with the heating unit 113 in between is detected. To detect. In the flow rate measurement device 1, the sensor element 100 having substantially the same structure is used for the flow rate detection unit 11 and the physical property value detection unit 12, and the arrangement angle of the sensor element 100 with respect to the flow direction of the fluid is determined by a plan view of the sensor element 100. They are arranged 90 degrees apart. Thereby, the sensor element 100 having the same structure can be used for the flow rate detection unit 11 and the physical property value detection unit 12, and the manufacturing cost of the flow rate measurement device 1 can be suppressed.
　一方、図７に示すように、物性値検出部１２は、測定対象流体の温度を検出する第１サーモパイル（温度検出部ともいう。）１２１および第２サーモパイル（温度検出部ともいう。）１２２と、測定対象流体を加熱するマイクロヒータ（加熱部ともいう。）１２３とを備えている。加熱部１２３と、温度検出部１２１および温度検出部１２２とは、物性値検出部１２内において、測定対象流体の流れ方向Ｑと直交する方向に並んで配置されている。また、加熱部１２３、温度検出部１２１、および温度検出部１２２の形状は、平面視においてそれぞれ略矩形であり、各々の長手方向は測定対象流体の流れ方向Ｑに沿っている。また、温度検出部１２１および温度検出部１２２は、加熱部１２３を挟んで左右対称に配置されており、加熱部１２３の両側の対称な位置の温度を検出する。したがって、温度検出部１２１および温度検出部１２２の測定値はほぼ同一であり、平均値を採用するようにしてもよいし、いずれか一方の値を採用するようにしてもよい。 On the other hand, as shown in FIG. 7, the physical property value detection unit 12 includes a first thermopile (also referred to as a temperature detection unit) 121 and a second thermopile (also referred to as a temperature detection unit) 122 that detect the temperature of the fluid to be measured. , And a micro heater (also referred to as a heating unit) 123 for heating the fluid to be measured. The heating unit 123, the temperature detecting unit 121, and the temperature detecting unit 122 are arranged in the physical property value detecting unit 12 side by side in a direction orthogonal to the flow direction Q of the fluid to be measured. The shapes of the heating unit 123, the temperature detecting unit 121, and the temperature detecting unit 122 are substantially rectangular in a plan view, and the longitudinal direction of each is along the flow direction Q of the fluid to be measured. Further, the temperature detection unit 121 and the temperature detection unit 122 are arranged symmetrically with the heating unit 123 in between, and detect temperatures at symmetrical positions on both sides of the heating unit 123. Therefore, the measured values of the temperature detection unit 121 and the temperature detection unit 122 are almost the same, and the average value may be adopted, or either one of them may be adopted.
＜機能構成＞
　図８は、流量測定装置１の機能構成の一例を示す機能ブロック図である。流量測定装置１は、流量検出部１１と、物性値検出部１２と、制御部１３と、通信部１５とを備えている。流量検出部１１は、温度検出部１１１と、温度検出部１１２とを備える。物性値検出部１２は、温度検出部１２１と、温度検出部１２２とを備える。なお、図６に示した加熱部１１３及び図７に示した加熱部１２３は、図示を省略している。また、制御部１３は、検出値取得部１３１と、特性値算出部１３２と、流量算出部１３３及び、出力制御部１３５を含む。 <Functional configuration>
FIG. 8 is a functional block diagram showing an example of the functional configuration of the flow rate measuring device 1. The flow rate measurement device 1 includes a flow rate detection unit 11, a physical property value detection unit 12, a control unit 13, and a communication unit 15. The flow rate detection unit 11 includes a temperature detection unit 111 and a temperature detection unit 112. The physical property value detection unit 12 includes a temperature detection unit 121 and a temperature detection unit 122. It should be noted that the heating unit 113 shown in FIG. 6 and the heating unit 123 shown in FIG. 7 are not shown. The control unit 13 also includes a detection value acquisition unit 131, a characteristic value calculation unit 132, a flow rate calculation unit 133, and an output control unit 135.
　流量検出部１１は、温度検出部１１１において検出された温度に応じた信号と温度検出部１１２において検出された温度に応じた信号を、制御部１３の検出値取得部１３１に出力する。物性値検出部１２は、温度検出部１２１において検出された温度に応じた信号を特性値算出部１３２に出力する。なお、物性値検出部１２は、温度検出部１２１および温度検出部１２２において検出された温度に応じた信号の平均値を求め、特性値算出部１３２に出力するようにしてもよい。また、温度検出部１２１又は温度検出部１２２のいずれか一方を用いて温度に応じた信号を取得するようにしてもよい。 The flow rate detection unit 11 outputs a signal according to the temperature detected by the temperature detection unit 111 and a signal according to the temperature detected by the temperature detection unit 112 to the detection value acquisition unit 131 of the control unit 13. The physical property value detection unit 12 outputs a signal corresponding to the temperature detected by the temperature detection unit 121 to the characteristic value calculation unit 132. The physical property value detection unit 12 may obtain an average value of signals according to the temperatures detected by the temperature detection unit 121 and the temperature detection unit 122 and output the average value to the characteristic value calculation unit 132. Alternatively, either the temperature detecting unit 121 or the temperature detecting unit 122 may be used to acquire a signal according to the temperature.
　検出値取得部１３１は、所定の測定間隔で、流量検出部１１における温度検出部１１１及び温度検出部１１２が出力する温度の検出値を取得し、温度検出部１１１による温度の検出値または、温度検出部１１１及び温度検出部１１２の温度の検出値の差分を出力する。特性値算出部１３２は、物性値検出部１２の温度検出部１２１及び温度検出部１２２の少なくともいずれかの検出値に基づいて特性値を算出する。なお、特性値算出部１３２は、物性値検出部１２のマイクロヒータの温度を変化させ、変化の前後において温度検出部１２１や温度検出部１２２が検出した測定対象流体の温度の差に所定の係数を乗じて特性値を算出するようにしてもよい。 The detection value acquisition unit 131 acquires the detection value of the temperature output by the temperature detection unit 111 and the temperature detection unit 112 in the flow rate detection unit 11 at a predetermined measurement interval, and the detection value of the temperature by the temperature detection unit 111 or the temperature The difference between the temperature detection values of the detection unit 111 and the temperature detection unit 112 is output. The characteristic value calculation unit 132 calculates the characteristic value based on the detection value of at least one of the temperature detection unit 121 and the temperature detection unit 122 of the physical property value detection unit 12. The characteristic value calculation unit 132 changes the temperature of the micro heater of the physical property value detection unit 12, and a predetermined coefficient is used for the difference between the temperatures of the fluid to be measured detected by the temperature detection unit 121 and the temperature detection unit 122 before and after the change. The characteristic value may be calculated by multiplying by.
　流量算出部１３３は、検出値取得部１３１の出力に基づいて、流体の流量を算出する。このとき、流量算出部１３３は、物性値検出部１２が算出した特性値を用いて流量を補正するようにしてもよい。また、出力制御部１３５は、検出値取得部１３１が出力した、温度検出部１１１による温度の検出値または、温度検出部１１１及び温度検出部１１２の温度の検出値の差分の何れから算出した流量を、流量算出部１３３から出力するかを決定する。通信部１５は、制御部１３において処理した情報を外部に対して無線または有線で送信し、外部から指令や設定値を無線または有線で受信し制御部１３に伝達する。 The flow rate calculation unit 133 calculates the flow rate of the fluid based on the output of the detection value acquisition unit 131. At this time, the flow rate calculation unit 133 may correct the flow rate by using the characteristic value calculated by the physical property value detection unit 12. In addition, the output control unit 135 calculates a flow rate calculated from either the temperature detection value output by the detection value acquisition unit 131 by the temperature detection unit 111 or the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112. Is output from the flow rate calculation unit 133. The communication unit 15 wirelessly or wiredly transmits the information processed by the control unit 13 to the outside, receives commands or set values from the outside wirelessly or by wire, and transmits them to the control unit 13.
　図９には、流量算出部１３３のより詳細な機能ブロック図を示す。流量算出部１３３には、第一流量算出部１３６と第二流量算出部１３７が設けられている。この第一流量算出部１３６は、温度検出部１１１及び温度検出部１１２の温度の検出値の差分より流体の流量を算出する機能を有する。また、第二流量算出部１３７は、加熱部１１３の上流側に配置された温度検出部１１１による温度の検出値より流体の流量を算出する機能を有する。 FIG. 9 shows a more detailed functional block diagram of the flow rate calculation unit 133. The flow rate calculation unit 133 is provided with a first flow rate calculation unit 136 and a second flow rate calculation unit 137. The first flow rate calculation unit 136 has a function of calculating the flow rate of the fluid from the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112. Further, the second flow rate calculation unit 137 has a function of calculating the flow rate of the fluid based on the temperature detection value of the temperature detection unit 111 arranged on the upstream side of the heating unit 113.
　また、第一流量算出部１３６には、温度検出部１１１及び温度検出部１１２の温度の検出値の差分を、差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流体の流量を算出する第一補正演算部１３６ａと、温度検出部１１１及び温度検出部１１２の温度の検出値の差分を、多項式演算することで、流量を算出する第一多項式演算部１３６ｂと、が備えられている。さらに、第二流量算出部１３７には、加熱部１１３の上流側に配置された温度検出部１１１の出力値を、差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第二補正演算部１３７ａが設けられている。 Further, the first flow rate calculation unit 136 corrects the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112 using a conversion data table including conversion data set corresponding to the difference value. The first correction calculation unit 136a that calculates the flow rate of the fluid and the difference between the temperature detection values of the temperature detection unit 111 and the temperature detection unit 112 are calculated by polynomial calculation. And a term expression calculation unit 136b. Further, the second flow rate calculation unit 137 uses the conversion data table including the conversion data set for the output value of the temperature detection unit 111 arranged on the upstream side of the heating unit 113, corresponding to the difference value. A second correction calculation unit 137a that calculates the flow rate by performing the correction calculation is provided.
　流量測定装置１の流量算出部１３３においては、基本的に、温度検出部１１１及び温度検出部１１２の検出値の差分に基づいて、流体の流量を算出している。図１０には、温度検出部１１１の検出値であるＴＡ１出力、温度検出部１１２の検出値であるＴＢ１出力、温度検出部１１１及び温度検出部１１２の検出値の差分であるＦＶ１出力の、流量の変化に対する推移を示す。しかしながら、特に、流量が図１０に示す領域Ｂ及び領域Ｃのような中流量～大流量の領域に属する場合には、ＦＶ１出力を検出値としたときに、流量を正確に検出することが困難となる場合があった。これに対し、従来より、このような状況が生じた場合には、出力制御部１３５は、温度検出部１１１の検出値であるＴＡ１出力のみを用いて、流量算出部１３３において流量を算出し、出力するようにしていた。これは、流体の流量が中流量～大流量の領域に属する場合には、ＦＶ１出力を検出値とするよりも、温度検出部１１１の検出値であるＴＡ１出力を検出値とした方が、精度の良い流量が得られることが実験的に分かっていたからである。ここで、流量が領域Ｂ及び領域Ｃのような中流量～大流量の領域に属する場合は、本実施例における所定の条件に相当する。 The flow rate calculation unit 133 of the flow rate measurement device 1 basically calculates the flow rate of the fluid based on the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112. In FIG. 10, the flow rate of TA1 output that is the detection value of the temperature detection unit 111, TB1 output that is the detection value of the temperature detection unit 112, and FV1 output that is the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112. Shows the change with respect to. However, it is difficult to accurately detect the flow rate when the FV1 output is used as the detection value, particularly when the flow rate belongs to a medium flow rate to high flow rate region such as the regions B and C shown in FIG. There were cases where On the other hand, conventionally, when such a situation occurs, the output control unit 135 calculates the flow rate in the flow rate calculation unit 133 using only the TA1 output that is the detection value of the temperature detection unit 111, I was trying to output. This is because, when the flow rate of the fluid belongs to the region of medium flow rate to high flow rate, it is more accurate to use the TA1 output, which is the detection value of the temperature detection unit 111, as the detection value than the FV1 output as the detection value. This is because it was experimentally known that a good flow rate of Here, when the flow rate belongs to a medium flow rate to high flow rate region such as the region B and the region C, it corresponds to the predetermined condition in the present embodiment.
　しかしながら、上記のような状況でさらに、流体温度が急激に変化し、流体温度と環境温度（例えば、流量測定装置１内の温度を含む）の間に温度差が生じるような場合には、温度検出部１１１の出力が極端に不安定となり変化してしまう場合があった。図１１を用いて、この状況についてより詳細に説明する。図１１（ａ）は横軸が時間、縦軸が流体温度を示しており、時刻ｔ１までは流体温度が安定しているが、時刻ｔ１～ｔ２の間では、流体温度が急上昇し、時刻ｔ２以降は再度安定する場合について示している。このような場合には、時刻ｔ１までの時間は、流体温度と環境温度が同等の温度である。そして、時刻ｔ１～ｔ２においては、流体温度が急激に上昇して流体温度と環境温度の間に温度差が生じ、さらに時刻ｔ２以降は、環境温度が流体温度と同様に上昇するため再度、流体温度と環境温度が同等の温度となる。 However, in the above situation, when the fluid temperature further rapidly changes and a temperature difference occurs between the fluid temperature and the environmental temperature (including the temperature inside the flow rate measuring device 1), the temperature The output of the detection unit 111 may be extremely unstable and may change. This situation will be described in more detail with reference to FIG. In FIG. 11A, the horizontal axis represents time and the vertical axis represents fluid temperature. The fluid temperature is stable until time t1, but the fluid temperature rises sharply between times t1 and t2, and time t2. The following shows the case where it becomes stable again. In such a case, the fluid temperature is equal to the environmental temperature until the time t1. Then, from time t1 to t2, the fluid temperature rises sharply to cause a temperature difference between the fluid temperature and the environment temperature, and after time t2, the environment temperature rises similarly to the fluid temperature, so that the fluid temperature is increased again. The temperature is the same as the ambient temperature.
　図１１（ｂ）には、上記のような状態における温度検出部１１１の出力であるＴＡ１出力の変化を示す。なお、ここでは流量の範囲が領域Ｂである場合について示している。図１１（ｂ）に示すように、流体温度が急激に変化し、流体温度と環境温度との間に温度差が生じる状態では、ＴＡ１出力が極端に不安定になってしまい、正確な流量測定が不可能となってしまう場合があった。 FIG. 11B shows a change in the TA1 output which is the output of the temperature detection unit 111 in the above state. Note that here, the case where the range of the flow rate is the region B is shown. As shown in FIG. 11B, when the fluid temperature changes abruptly and a temperature difference occurs between the fluid temperature and the ambient temperature, the TA1 output becomes extremely unstable, and accurate flow rate measurement is performed. In some cases, it became impossible.
　このような問題に対し、本実施例においては、流量が図１０に示す領域Ｂまたは領域Ｃの中流量～大流量の領域に属している場合であっても、ＴＡ１出力の値が極端に不安定になっている場合には、ＴＡ１出力ではなく、ＴＡ１出力とＴＢ１出力の差であるＦＶ１出力に基づいて流体の流量を算出することとした。また、ＴＡ１出力が図１１（ｂ）のｔ１～ｔ２に示すように極端に不安定になっていることを、ＴＡ１出力とＦＶ１出力の間の偏差が所定の閾値以上であることで検出することにした。 To deal with such a problem, in the present embodiment, even if the flow rate belongs to the region B or the region C shown in FIG. When it is stable, the fluid flow rate is calculated based on the FV1 output, which is the difference between the TA1 output and the TB1 output, instead of the TA1 output. Further, it is detected that the TA1 output is extremely unstable as indicated by t1 to t2 in FIG. 11B by the deviation between the TA1 output and the FV1 output being equal to or more than a predetermined threshold value. I chose
　図１２には、本実施例における流量測定ルーチン１のフローチャートを示す。本ルーチンは、回路基板５に備えられたメモリに記憶されたプログラムであり、制御部１３の流量算出部１３３により、所定時間毎に実行される。 FIG. 12 shows a flow chart of the flow rate measurement routine 1 in this embodiment. This routine is a program stored in the memory provided in the circuit board 5, and is executed by the flow rate calculation unit 133 of the control unit 13 at predetermined time intervals.
　本ルーチンが実行されると、ステップＳ１０１において、流体の流量が領域Ａに属するか否かが判定される。ここで、流体の流量が領域Ａに属すると肯定判定された場合には、流体の流量が低流量であり、温度検出部１１１及び温度検出部１１２の検出値の差であるＦＶ１出力に基づいて、流体の流量を算出しても問題ないと判断されるので、ステップＳ１０３に進む。一方、流体の流量が領域Ａに属しないと判定された場合には、流体の流量が領域Ｂまたは領域Ｃに属し、温度検出部１１１及び温度検出部１１２の検出値の差であるＦＶ１出力に基づいて、流体の流量を算出した場合には、測定精度が低下すると判断されるので、ステップＳ１０２に進む。 When this routine is executed, it is determined in step S101 whether the flow rate of the fluid belongs to the area A. Here, when it is positively determined that the fluid flow rate belongs to the region A, the fluid flow rate is low, and based on the FV1 output that is the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112. , It is determined that there is no problem even if the flow rate of the fluid is calculated, so the process proceeds to step S103. On the other hand, when it is determined that the fluid flow rate does not belong to the area A, the fluid flow rate belongs to the area B or the area C, and the FV1 output that is the difference between the detection values of the temperature detection unit 111 and the temperature detection unit 112 is output. If the flow rate of the fluid is calculated based on this, it is determined that the measurement accuracy will decrease, so the process proceeds to step S102.
　ステップＳ１０２においては、温度検出部１１１の検出値であるＴＡ１出力のみに基づいて、流量算出部１３３において流量ＦＶＯ（ＴＡ１）を算出する。ステップＳ１０２の処理が終了するとＳ１０４に進む。また、ステップＳ１０３においては、温度検出部１１１のＴＡ１出力と温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力に基づいて、流量算出部１３３において流量ＦＶＯ（ＦＶ１）を算出する。ステップＳ１０３の処理が終了すると後述するステップＳ１０８に進む。 In step S102, the flow rate calculation unit 133 calculates the flow rate FVO (TA1) based only on the TA1 output that is the detection value of the temperature detection unit 111. When the process of step S102 ends, the process proceeds to S104. In step S103, the flow rate calculation unit 133 calculates the flow rate FVO (FV1) based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. When the process of step S103 ends, the process proceeds to step S108 described below.
　ステップＳ１０４においては、温度検出部１１１の検出値であるＴＡ１出力のみに基づいて、流量算出部１３３において流量ＦＶＯ（ＴＡ１）を算出した場合には、流体の温度変化によって、ＴＡ１出力が不安定化することに備え、ここでも温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力に基づいて、流量算出部１３３において流量ＦＶＯ（ＦＶ１）を算出する。ステップＳ１０４の処理が終了するとステップＳ１０５に進む。 In step S104, if the flow rate calculation unit 133 calculates the flow rate FVO (TA1) based only on the TA1 output that is the detection value of the temperature detection unit 111, the TA1 output becomes unstable due to the temperature change of the fluid. In preparation for this, the flow rate calculation unit 133 also calculates the flow rate FVO (FV1) based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. When the process of step S104 ends, the process proceeds to step S105.
　ステップＳ１０５においては、流体の流量が領域Ｂに属するか否かが判定される。ここで、流体の流量の範囲が領域Ｂに属すると肯定判定された場合には、ステップＳ１０７に進む。一方、流体の流量の範囲が領域Ｂでないと否定判定された場合には、流体の流量が領域Ｃに属すると判断されるので、ステップＳ１０６に進む。ステップＳ１０６では、温度検出部１１１のＴＡ１出力のみに基づいて算出された流量ＦＶＯ（ＴＡ１）と、温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力に基づいて算出された流量ＦＶＯ（ＦＶ１）との偏差が閾値１以上か否かを判定する。 In step S105, it is determined whether or not the fluid flow rate belongs to region B. Here, if it is determined that the range of the flow rate of the fluid belongs to the region B, the process proceeds to step S107. On the other hand, when the negative determination is made that the range of the flow rate of the fluid is not in the region B, it is determined that the flow rate of the fluid belongs to the region C, and the process proceeds to step S106. In step S106, the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 and the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 are calculated. It is determined whether the deviation from the calculated flow rate FVO (FV1) is equal to or more than the threshold value 1.
　ここで、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）との偏差が閾値１以上と判定された場合には、流体温度の急激な変化によりＴＡ１出力が不安定になっていると判断されるので、ステップＳ１０８に進む。一方、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）との偏差が閾値１未満と判定された場合には、ＴＡ１出力が安定していると判断されるので、ステップＳ１０９に進む。 Here, when the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is determined to be equal to or greater than the threshold value 1, it is determined that the TA1 output is unstable due to the rapid change in the fluid temperature. , And proceeds to step S108. On the other hand, if it is determined that the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is less than the threshold value 1, it is determined that the TA1 output is stable, and the process proceeds to step S109.
　また、ステップＳ１０６では、温度検出部１１１のＴＡ１出力のみに基づいて算出された流量ＦＶＯ（ＴＡ１）と、温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力に基づいて算出された流量ＦＶＯ（ＦＶ１）との偏差が閾値２以上か否かを判定する。 Further, in step S106, based on the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 and the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. It is determined whether or not the deviation from the calculated flow rate FVO (FV1) is greater than or equal to the threshold value 2.
　ここで、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）との偏差が閾値２以上と判定された場合には、流体温度の急激な変化によりＴＡ１出力が不安定になっていると判断されるので、ステップＳ１０８に進む。一方、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）との偏差が閾値２未満と判定された場合には、ＴＡ１出力が安定していると判断されるので、ステップＳ１０９に進む。 Here, when it is determined that the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is equal to or greater than the threshold value 2, it is determined that the TA1 output is unstable due to the rapid change in the fluid temperature. , And proceeds to step S108. On the other hand, if it is determined that the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is less than the threshold value 2, it is determined that the TA1 output is stable, and the process proceeds to step S109.
　なお、本ルーチンにおいては、ステップＳ１０５において、肯定判定された場合と否定判定された場合とでは、
流体の流量が属する流量領域が異なるので、ＴＡ１出力が不安定になっているか否かが判定可能な閾値の値が異なることを想定して、ステップＳ１０６の処理とステップＳ１０７の処理とで異なる閾値を用いている。この閾値１及び閾値２は本発明の所定値に相当する。 In this routine, in step S105, a positive determination is made and a negative determination is made.
Since the flow rate region to which the flow rate of the fluid belongs is different, it is assumed that the threshold value that can be used to determine whether or not the TA1 output is unstable is different, and the different threshold values are used in the processing of step S106 and the processing of step S107. Is used. The threshold 1 and the threshold 2 correspond to the predetermined values of the present invention.
　次に、ステップＳ１０８においては、温度検出部１１１のＴＡ１出力のみに基づいて算出された流量ＦＶＯ（ＴＡ１）を出力する。ステップＳ１０９においては、温度検出部１１１のＴＡ１出力と、温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力に基づいて算出された流量ＦＶＯ（ＦＶ１）を出力する。Ｓ１０８またはＳ１０９の処理が終了すると本ルーチンを一旦終了する。 Next, in step S108, the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 is output. In step S109, the flow rate FVO (FV1) calculated based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 is output. When the process of S108 or S109 ends, this routine ends once.
　以上のように、従来の流量測定装置においては、本来は、流体の流量が中流量から大流量の領域に属する場合には、温度検出部１１１のＴＡ１出力のみに基づいて算出された流量ＦＶＯ（ＴＡ１）を出力する。これに対し本実施例においては、温度検出部１１１のＴＡ１出力のみに基づいて算出された流量ＦＶＯ（ＴＡ１）と、温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力に基づいて算出された流量ＦＶＯ（ＦＶ１）との偏差が閾値以上である場合には、温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力に基づいて算出された流量ＦＶＯ（ＦＶ１）を出力することとした。 As described above, in the conventional flow rate measuring device, when the flow rate of the fluid originally belongs to the region of medium flow rate to high flow rate, the flow rate FVO (calculated only based on the TA1 output of the temperature detection unit 111) TA1) is output. On the other hand, in the present embodiment, the flow rate FVO (TA1) calculated based only on the TA1 output of the temperature detection unit 111 and the difference FV1 between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. When the deviation from the flow rate FVO (FV1) calculated based on the output is equal to or more than the threshold value, it is calculated based on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. The flow rate FVO (FV1) is output.
　これにより、流体の温度が急激に変化し、温度検出部１１１の検出値であるＴＡ１出力が不安定になった場合には、ＦＶＯ（ＴＡ１）と比較して、より安定した流量ＦＶＯ（ＦＶ１）を出力することで、より多様な環境条件でも流量測定装置１の測定精度を高く維持することが可能となった。 As a result, when the temperature of the fluid suddenly changes and the TA1 output, which is the detection value of the temperature detection unit 111, becomes unstable, a more stable flow rate FVO (FV1) compared to FVO (TA1). By outputting, it becomes possible to maintain high measurement accuracy of the flow rate measuring device 1 even under various environmental conditions.
　なお、本実施例においては、流体の流量が領域Ｂに属するか領域Ｃに属するかで、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）との偏差と比較する閾値を変更する例について説明したが、必ずしも、流体の流量が領域Ｂに属するか領域Ｃに属するかで閾値を変更する必要はない。なお、流量測定ルーチン１におけるステップＳ１０３、Ｓ１０４は本発明における第一流量算出ステップに相当する。ステップＳ１０２は本発明における第二流量算出ステップに相当する。Ｓ１０８及びＳ１０９は本発明における出力ステップに相当する。 In the present embodiment, an example in which the threshold value to be compared with the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is changed depending on whether the flow rate of the fluid belongs to the region B or the region C has been described. It is not always necessary to change the threshold depending on whether the fluid flow rate belongs to the region B or the region C. Note that steps S103 and S104 in the flow rate measurement routine 1 correspond to the first flow rate calculation step in the present invention. Step S102 corresponds to the second flow rate calculating step in the present invention. S108 and S109 correspond to the output step in the present invention.
　図１３には、本実施例における制御を行った場合の、流量測定装置１の出力の変化の例を示す。なお、図１３の前提として、流体の流量は中流量～大流量の領域に属するものとする。図１３の横軸は時間、縦軸は、流量測定装置１による出力値の誤差（真の流量値からの誤差）及び、流体温度である。 FIG. 13 shows an example of changes in the output of the flow rate measuring device 1 when the control in this embodiment is performed. As a premise of FIG. 13, it is assumed that the flow rate of the fluid belongs to the region of medium flow rate to high flow rate. The horizontal axis of FIG. 13 is time, and the vertical axis is the error of the output value by the flow rate measuring device 1 (error from the true flow rate value) and the fluid temperature.
　図１３を見ると、時間が１時間未満の時間帯においては、流体温度は安定している。その状態では、流量測定装置１は出力として流量ＦＶＯ（ＴＡ１）を出力しており、充分に精度のよい測定が行われている。その後、流体温度が急激に変化し始めると、流量ＦＶＯ（ＴＡ１）の誤差の値が急激に変化し、－２０％を下回る。そのタイミングで、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）の偏差が閾値以上となり、流量測定装置１の出力がＦＶＯ（ＴＡ１）からＦＶＯ（ＦＶ１）に切換えられる。そのことにより、誤差の値は回復し、ＦＶＯ（ＦＶ１）とＦＶＯ（ＴＡ１）の偏差程度の値となる。なお、この際、流量ＦＶＯ（ＴＡ１）の値は、図中細い破線で示すように極端に低下し不安定になっている。 Looking at FIG. 13, the fluid temperature is stable in the time zone of less than 1 hour. In that state, the flow rate measuring device 1 outputs the flow rate FVO (TA1) as an output, and sufficiently accurate measurement is performed. After that, when the fluid temperature starts to change rapidly, the error value of the flow rate FVO (TA1) changes rapidly and falls below -20%. At that timing, the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) becomes greater than or equal to the threshold value, and the output of the flow rate measuring device 1 is switched from FVO (TA1) to FVO (FV1). As a result, the value of the error is recovered to a value that is about the deviation between FVO (FV1) and FVO (TA1). At this time, the value of the flow rate FVO (TA1) is extremely reduced and unstable as indicated by a thin broken line in the figure.
　そして、時間とともに流体温度の変化が緩やかになると、流量ＦＶＯ（ＴＡ１）の値が急回復し、ＦＶＯ（ＴＡ１）の誤差の値が－２０％を超える。そのタイミングで、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）の偏差が閾値未満となり、流量測定装置１の出力がＦＶＯ（ＦＶ１）からＦＶＯ（ＴＡ１）に再度切換えられる。図１３より、流量測定装置１の出力をＦＶＯ（ＴＡ１）に固定した場合と比較して、本実施例の制御によれば、流体温度の変化に拘わらず、流量測定装置１の出力を安定化することができ、より高精度な流量測定ができていることが理解できる。 Then, when the change in fluid temperature becomes gradual with time, the value of the flow rate FVO (TA1) rapidly recovers, and the error value of FVO (TA1) exceeds -20%. At that timing, the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) becomes less than the threshold value, and the output of the flow rate measuring device 1 is switched from FVO (FV1) to FVO (TA1) again. From FIG. 13, compared with the case where the output of the flow rate measuring device 1 is fixed to FVO (TA1), according to the control of this embodiment, the output of the flow rate measuring device 1 is stabilized regardless of the change of the fluid temperature. Therefore, it can be understood that the flow rate can be measured with higher accuracy.
〔実施例２〕
　次に、本発明の実施例２について説明する。本実施例においては、本発明を実施するにあたり、流量測定装置１が備えるべきメモリの容量を可及的に低減することを可能とした例について説明する。 [Example 2]
Next, a second embodiment of the present invention will be described. In the present embodiment, an example in which the capacity of the memory that the flow rate measurement device 1 should have can be reduced as much as possible in carrying out the present invention will be described.
　ここで、従来の流量測定装置においては、温度検出部１１１のＴＡ１出力から流量ＦＶＯ（ＴＡ１）を算出する際や、温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力から流量ＦＶＯ（ＦＶ１）を算出する際には、ＴＡ１出力やＦＶ１出力の値を変換データにより補正演算していた。よって、ＴＡ１出力やＦＶ１出力の値を流量ＦＶＯ（ＴＡ１）や流量ＦＶＯ（ＦＶ１）に補正演算するための変換データテーブルを、複数のガス温度に対して準備する必要があった。この変換データテーブルについては、ＴＡ１出力あるいはＦＶ１出力と流量の関係の曲線を想定した場合に、流量の領域について数百ポイント×環境温度に関して複数種類×流体の種類に関して複数種類のデータ、すなわち、合計数千のデータを記憶しておく必要があった。 Here, in the conventional flow rate measuring device, when the flow rate FVO (TA1) is calculated from the TA1 output of the temperature detection unit 111, or when the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 is FV1. When calculating the flow rate FVO (FV1) from the output, the values of the TA1 output and the FV1 output were corrected and calculated using the conversion data. Therefore, it is necessary to prepare a conversion data table for a plurality of gas temperatures for correcting the values of the TA1 output and the FV1 output to the flow rate FVO (TA1) and the flow rate FVO (FV1). Regarding this conversion data table, assuming a curve of the relationship between TA1 output or FV1 output and flow rate, several hundred points of flow rate region x multiple types of environmental temperature x multiple types of fluid type, that is, total Thousands of data had to be stored.
　図１４には、従来から用いられている変換データテーブルによる補正演算の例について示す。図１４は、温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力から流量ＦＶＯ（ＦＶ１）を算出する際の補正演算について示している。図１４において、（１）の曲線は、ＦＶ１出力と流量との関係を示す。そして、この補正演算においては、（１）の曲線に対して、オフセットを加えて原点を通過する曲線（２）に変換し、さらに、ゲインを乗じて高感度の曲線（３）に変換し、最終的には、流量範囲における最小と最大の流量において、曲線（３）と出力が一致する直線（４）になるような変換を行っている。この変換を行うために、流量範囲に関して、数百ポイントの変換データが記憶され、このような変換データが、環境温度に関して複数種類分、流体の種類に関して複数種類分記憶されていることになる。この数百ポイントという数値は、本発明における所定数の差分に相当する。 FIG. 14 shows an example of a correction calculation using a conversion data table that has been conventionally used. FIG. 14 shows a correction calculation when calculating the flow rate FVO (FV1) from the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. In FIG. 14, the curve (1) shows the relationship between the FV1 output and the flow rate. Then, in this correction calculation, an offset is added to the curve of (1) to convert it into a curve (2) that passes through the origin, and further it is multiplied by a gain to be converted into a highly sensitive curve (3). Finally, at the minimum and maximum flow rates in the flow rate range, conversion is performed so that the curve (3) and the output coincide with the straight line (4). In order to perform this conversion, conversion data of several hundred points is stored for the flow rate range, and such conversion data is stored for a plurality of types of environmental temperatures and a plurality of types of fluid types. The numerical value of several hundreds of points corresponds to a predetermined number of differences in the present invention.
　このように、例えばＦＶ１出力を流量ＦＶＯ（ＦＶ１）に変換するために、多くのデータを含む変換データテーブルが記憶されているのであるが、本実施例において流量ＦＶＯ（ＴＡ１）が不安定となり流量ＦＶＯ（ＦＶ１）を出力する場合には、流体の温度変化が大きい状況であるので、既にメモリに記憶されている変換データテーブルは使えない状況となっていた。そして、そのために、既にメモリに記憶されている変換データテーブルとは異なるテーブルをメモリに新たに記憶することは、流量測定装置１として備えるべきメモリの容量を拡張する事に繋がり、装置のコストダウンの妨げになる虞があった。 Thus, for example, in order to convert the FV1 output into the flow rate FVO (FV1), a conversion data table containing a large amount of data is stored. However, in the present embodiment, the flow rate FVO (TA1) becomes unstable and the flow rate is In the case of outputting FVO (FV1), since the temperature change of the fluid is large, the conversion data table already stored in the memory cannot be used. Therefore, for that reason, newly storing a table different from the conversion data table already stored in the memory in the memory leads to expansion of the capacity of the memory to be provided as the flow rate measuring device 1, which leads to cost reduction of the device. Could hinder the
　それに対し、本実施例では、ＦＶ１出力から流量ＦＶＯ（ＦＶ１）を算出する際には、ＦＶ１出力に対して多項式演算を行うことで流量ＦＶＯ（ＦＶ１）を取得することとした。図１５を用いて、この多項式演算について説明する。図１５において実線で示されるのは、実験的に求められたＦＶ１出力と流量の関係の曲線である。本実施例では、この曲線を以下の式（２）のように３次多項式で近似する。
　　　　　　　　　ｙ＝ａｘ３＋ｂｘ２＋ｃｘ＋ｄ・・・・・（２）
　ここで、ａ、ｂ、ｃ、ｄは係数。ｘはＦＶ１出力の値、ｙは流量ＦＶＯ（ＦＶ１）の値である。 On the other hand, in this embodiment, when calculating the flow rate FVO (FV1) from the FV1 output, the flow rate FVO (FV1) is acquired by performing a polynomial operation on the FV1 output. This polynomial calculation will be described with reference to FIG. A solid line in FIG. 15 is a curve of the relationship between the FV1 output and the flow rate obtained experimentally. In the present embodiment, this curve is approximated by a cubic polynomial as in the following equation (2).
y = ax 3 + bx 2 + cx + d (2)
Where a, b, c and d are coefficients. x is the FV1 output value, and y is the flow rate FVO (FV1) value.
　そして、温度検出部１１１のＴＡ１出力及び温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力が取得されると、このＦＶ１出力に対して（２）式による多項式演算を行うことで、流量ＦＶＯ（ＦＶ１）を算出する。 When the FV1 output, which is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112, is acquired, the flow rate FVO ( FV1) is calculated.
　本実施例においては、このような多項式演算を様々なＦＶ１に対して行うため、係数ａ、ｂ、ｃ、ｄを３種類の環境温度と、３種類の流体種類について記憶させておく。これにより、ＦＶ１出力から流量ＦＶＯ（ＦＶ１）を算出するために必要なメモリ容量を各段に少なくすることができ、装置コストの低減を図ることができる。なお、従来の変換データテーブルでは、ＦＶＯ（ＦＶ１）またはＦＶＯ（ＴＡ１）と実際の流量との間の関係が概略リニアになるような変換を行っていたが、本実施例においてはＦＶ１出力と流量との関係の曲線を３次多項式で近似し、特に直線性の向上を図っていない。これは、本実施例における制御が適用される場合は緊急事態に対応するものであるので、メモリ容量の低減を優先したことによる。 In this embodiment, since such a polynomial operation is performed on various FV1, the coefficients a, b, c, d are stored for three kinds of environmental temperatures and three kinds of fluids. As a result, the memory capacity required for calculating the flow rate FVO (FV1) from the FV1 output can be reduced in each stage, and the device cost can be reduced. In the conventional conversion data table, conversion is performed so that the relationship between FVO (FV1) or FVO (TA1) and the actual flow rate is approximately linear, but in the present embodiment, the FV1 output and the flow rate are changed. The curve of the relationship between and is approximated by a third-order polynomial, and the linearity is not particularly improved. This is because the case where the control in this embodiment is applied corresponds to an emergency situation, so that reduction of the memory capacity is prioritized.
　図１６には、本実施例における流量測定ルーチン２のフローチャートを示す。本ルーチンと、実施例１で説明した流量測定ルーチン１との相違点は、ステップＳ１０２の処理の代わりにステップＳ２０２の処理を、ステップＳ１０３の処理の代わりにステップＳ２０３の処理を、ステップＳ１０４の処理の代わりにステップＳ２０４の処理を実行する点である。 FIG. 16 shows a flowchart of the flow rate measurement routine 2 in this embodiment. The difference between this routine and the flow rate measurement routine 1 described in the first embodiment is that the process of step S202 is replaced by the process of step S102, the process of step S203 is replaced by the process of step S103, and the process of step S104. The point is that the process of step S204 is executed instead of.
　本実施例においては、ステップＳ１０１で流体の流量が領域Ａに属しない、すなわち流体の流量が領域Ｂまたは領域Ｃに属すると判定された場合には、ステップＳ２０２に進み、温度検出部１１１のＴＡ１出力を補正データテーブルを用いて補正演算することで、流量ＦＶＯ（ＴＡ１）を算出する。また、ステップＳ１０１で流体の流量が領域Ａに属すると判定された場合には、ステップＳ２０３に進み、温度検出部１１１のＴＡ１出力と温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力を補正データテーブルを用いて補正演算することで、流量ＦＶＯ（ＦＶ１）を算出する。 In the present embodiment, when it is determined in step S101 that the fluid flow rate does not belong to the area A, that is, the fluid flow rate belongs to the area B or the area C, the process proceeds to step S202 and TA1 of the temperature detection unit 111 is detected. The flow rate FVO (TA1) is calculated by correcting the output using the correction data table. When it is determined that the flow rate of the fluid belongs to the region A in step S101, the process proceeds to step S203, and the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112 is corrected data. The flow rate FVO (FV1) is calculated by performing a correction calculation using the table.
　そして、ステップＳ２０２の処理が終了するとＳ２０４に進み、ここでは、温度検出部１１１のＴＡ１出力と温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力を、多項式演算することで、流量ＦＶＯ（ＦＶ１）を算出する。ステップＳ１０５以降の処理は、流量測定ルーチン１と同等であるので、ここでは説明を割愛する。以上のように、本実施例においては、流体の流量が中流量から大流量の領域に属する場合には、温度検出部１１１のＴＡ１出力を補正データテーブルによって補正演算することで、流量ＦＶＯ（ＴＡ１）を算出する。そして、温度検出部１１１のＴＡ１出力と温度検出部１１２のＴＢ１出力の差分であるＦＶ１出力を、多項式演算することで、流量ＦＶＯ（ＦＶ１）を算出する。そして、流量ＦＶＯ（ＴＡ１）と流量ＦＶＯ（ＦＶ１）の偏差が閾値以上か否かを判定することにより、流体の温度変化の影響を受けてＴＡ１出力が不安定になっているか否かを判断する。 When the process of step S202 ends, the process proceeds to step S204, in which the flow rate FVO (FV1) is calculated by polynomial calculation of the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. To calculate. Since the processing after step S105 is the same as that of the flow rate measurement routine 1, the description is omitted here. As described above, in the present embodiment, when the flow rate of the fluid belongs to the region of medium flow rate to high flow rate, the TA1 output of the temperature detection unit 111 is corrected and calculated by the correction data table, and the flow rate FVO (TA1 ) Is calculated. Then, the flow rate FVO (FV1) is calculated by performing a polynomial operation on the FV1 output that is the difference between the TA1 output of the temperature detection unit 111 and the TB1 output of the temperature detection unit 112. Then, by determining whether the deviation between the flow rate FVO (TA1) and the flow rate FVO (FV1) is greater than or equal to a threshold value, it is determined whether the TA1 output is unstable due to the influence of the temperature change of the fluid. .
　よって、本実施例では、ＴＡ１出力が流体の温度変化の影響を受けて不安定になっているか否かの判断を、可及的に少ない容量のデータを用いて実施することができ、流量測定装置１に必要なメモリ容量を低減でき、装置のコストダウンを促進することが可能である。なお、流量測定ルーチン２において、ステップＳ２０３は本発明における第一補正演算工程に相当する。ステップＳ２０４は第一多項式演算工程に相当する。ステップＳ２０２は第二補正演算工程に相当する。 Therefore, in this embodiment, it is possible to determine whether or not the TA1 output is unstable due to the influence of the temperature change of the fluid by using the data of the smallest possible volume, and the flow rate measurement. The memory capacity required for the device 1 can be reduced, and the cost of the device can be reduced. In the flow rate measurement routine 2, step S203 corresponds to the first correction calculation step in the present invention. Step S204 corresponds to the first polynomial calculation step. Step S202 corresponds to the second correction calculation step.
　なお、上記の実施例においては、流体の流量が中流量～大流量の領域に属するときには、加熱部１１３の上流側に配置された温度検出部１１１の検出値であるＦＶＯ（ＴＡ１）のみを用いて流量を算出する場合に、本発明を適用する例について説明した。しかしながら、本発明は、流体の流量が中流量～大流量の領域に属するときには、加熱部１１３の下流側に配置された温度検出部１１２の検出値であるＦＶＯ（ＴＢ１）のみを用いて流量を算出する場合に、適用しても構わない。 In the above embodiment, when the flow rate of the fluid belongs to the range of medium flow rate to high flow rate, only FVO (TA1) which is the detection value of the temperature detection unit 111 arranged on the upstream side of the heating unit 113 is used. An example in which the present invention is applied to the case of calculating the flow rate by using the above has been described. However, according to the present invention, when the flow rate of the fluid belongs to the region of medium flow rate to high flow rate, the flow rate is changed by using only the FVO (TB1) which is the detection value of the temperature detection section 112 arranged on the downstream side of the heating section 113. It may be applied when calculating.
　なお、以下には本発明の構成要件と実施例の構成とを対比可能とするために、本発明の構成要件を図面の符号付きで記載しておく。
＜発明１＞
　流路を流れる測定対象流体の流量を測定する流量測定装置（１）であって、
　測定対象流体を加熱する加熱部（１１３）と、
　前記加熱部（１１３）の両側に該加熱部（１１３）を前記測定対象流体の流れ方向に挟んで配置され、前記測定対象流体の温度を検出する複数の温度検出部（１１１、１１２）と、
　前記加熱部（１１３）の両側に配置された温度検出部（１１１、１１２）の出力値の差分より測定対象流体の流量を算出する第一流量算出部（１３６）と、
　前記加熱部（１１３）の片側に配置された温度検出部（１１１）の出力値より前記測定対象流体の流量を算出する第二流量算出部（１３７）と、
　を備え、
　前記測定対象流体の流量が所定の条件を満たす場合には、前記第二流量算出部（１３７）が算出した前記測定対象流体の流量を出力するとともに、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合であっても、前記第一流量算出部（１３６）が算出した前記測定対象流体の流量と、前記第二流量算出部（１３７）が算出した前記測定対象流体の流量との間の偏差が所定値以上の場合には、前記第一流量算出部（１３６）が算出した前記測定対象流体の流量を出力する出力制御部（１３５）を、
　さらに備えることを特徴とする、流量測定装置。
＜発明４＞
　測定対象流体を加熱する加熱部（１１３）と、
　前記加熱部（１１３）の両側に該加熱部（１１３）を前記測定対象流体の流れ方向に挟んで配置され、前記測定対象流体の温度を検出する複数の温度検出部（１１１、１１２）と、
　前記温度検出部（１１１、１１２）の出力値より測定対象流体の流量を算出する流量算出部（１３３）と、
　を備え、流路（２）を流れる測定対象流体の流量を検出する流量測定装置（１）の制御方法であって、
　前記加熱部（１１３）の両側に配置された温度検出部（１１１、１１２）の出力値の差分より測定対象流体の流量を算出する第一流量算出ステップ（Ｓ１０３、Ｓ１０４）と、
　前記加熱部の片側に配置された温度検出部の出力値より前記測定対象流体の流量を算出する第二流量算出ステップ（Ｓ１０２）と、
　前記測定対象流体の流量が所定の条件を満たす場合には、前記第二流量算出ステップにより算出された前記測定対象流体の流量を出力する（Ｓ１０９）とともに、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合であっても、前記第一流量算出ステップにおいて算出した前記測定対象流体の流量と、前記第二流量算出ステップにおいて算出した前記測定対象流体の流量との間の偏差が所定値以上の場合には、前記第一流量算出ステップにおいて算出した前記測定対象流体の流量を出力する（Ｓ１０８）出力ステップと、
　を有することを特徴とする、流量測定装置の制御方法。 In order to make it possible to compare the constituent features of the present invention with the constituent features of the embodiments, constituent features of the present invention will be described with reference numerals in the drawings.
<Invention 1>
A flow rate measuring device (1) for measuring a flow rate of a measurement target fluid flowing through a flow path, comprising:
A heating unit (113) for heating the fluid to be measured,
A plurality of temperature detection units (111, 112) arranged on both sides of the heating unit (113) so as to sandwich the heating unit (113) in the flow direction of the fluid to be measured, and to detect the temperature of the fluid to be measured;
A first flow rate calculation unit (136) for calculating the flow rate of the fluid to be measured from the difference between the output values of the temperature detection units (111, 112) arranged on both sides of the heating unit (113);
A second flow rate calculation unit (137) for calculating the flow rate of the fluid to be measured from the output value of the temperature detection unit (111) arranged on one side of the heating unit (113);
Equipped with
When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated by the second flow rate calculation unit (137) is output, and the range of the flow rate of the measurement target fluid is Even when a predetermined condition is satisfied, the flow rate of the measurement target fluid calculated by the first flow rate calculation unit (136) and the flow rate of the measurement target fluid calculated by the second flow rate calculation unit (137). When the deviation between the two is greater than or equal to a predetermined value, the output control unit (135) that outputs the flow rate of the measurement target fluid calculated by the first flow rate calculation unit (136) is
A flow measuring device, further comprising:
<Invention 4>
A heating unit (113) for heating the fluid to be measured,
A plurality of temperature detection units (111, 112) arranged on both sides of the heating unit (113) so as to sandwich the heating unit (113) in the flow direction of the fluid to be measured, and to detect the temperature of the fluid to be measured;
A flow rate calculation unit (133) that calculates the flow rate of the fluid to be measured from the output values of the temperature detection units (111, 112);
A method for controlling a flow rate measuring device (1), comprising:
A first flow rate calculation step (S103, S104) of calculating the flow rate of the fluid to be measured from the difference between the output values of the temperature detection sections (111, 112) arranged on both sides of the heating section (113),
A second flow rate calculation step (S102) of calculating the flow rate of the fluid to be measured from the output value of the temperature detection unit arranged on one side of the heating unit,
When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated in the second flow rate calculation step is output (S109), and the range of the flow rate of the measurement target fluid is Even when the predetermined condition is satisfied, the deviation between the flow rate of the measurement target fluid calculated in the first flow rate calculation step and the flow rate of the measurement target fluid calculated in the second flow rate calculation step is If it is equal to or more than a predetermined value, the flow rate of the fluid to be measured calculated in the first flow rate calculating step is output (S108), an output step,
A method for controlling a flow rate measuring device, comprising:
１　　　：流量測定装置
１１　　：流量検出部
１１１　：温度検出部
１１２　：温度検出部
１１３　：加熱部
１２　　：物性値検出部
１２１　：温度検出部
１２２　：温度検出部
１２３　：加熱部
１３　　：制御部
１３１　：検出値取得部
１３２　：特性値算出部
１３３　：流量算出部
１３５　：出力制御部
１３６　：第一流量算出部
１３６ａ：第一補正演算部
１３６ｂ：第一多項式演算部
１３７　：第二流量算出部
１３７ａ：第二補正演算部 1: Flow rate measuring device 11: Flow rate detection part 111: Temperature detection part 112: Temperature detection part 113: Heating part 12: Physical property value detection part 121: Temperature detection part 122: Temperature detection part 123: Heating part 13: Control part 131: Detection value acquisition unit 132: Characteristic value calculation unit 133: Flow rate calculation unit 135: Output control unit 136: First flow rate calculation unit 136a: First correction calculation unit 136b: First polynomial calculation unit 137: Second flow rate calculation unit 137a: Second correction calculation unit

Claims (6)

  1. 　流路を流れる測定対象流体の流量を測定する流量測定装置であって、
    　前記測定対象流体を加熱する加熱部と、
    　前記加熱部の両側に該加熱部を前記測定対象流体の流れ方向に挟んで配置され、前記測定対象流体の温度を検出する複数の温度検出部と、
    　前記加熱部の両側に配置された温度検出部の出力値の差分より測定対象流体の流量を算出する第一流量算出部と、
    　前記加熱部の片側に配置された温度検出部の出力値より前記測定対象流体の流量を算出する第二流量算出部と、
    　を備え、
    　前記測定対象流体の流量が所定の条件を満たす場合には、前記第二流量算出部が算出した前記測定対象流体の流量を出力するとともに、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合であっても、前記第一流量算出部が算出した前記測定対象流体の流量と、前記第二流量算出部が算出した前記測定対象流体の流量との間の偏差が所定値以上の場合には、前記第一流量算出部が算出した前記測定対象流体の流量を出力する出力制御部を、
    　さらに備えることを特徴とする、流量測定装置。     A flow rate measuring device for measuring the flow rate of a fluid to be measured flowing through a flow path,
    A heating unit for heating the fluid to be measured,
    A plurality of temperature detection units arranged on both sides of the heating unit with the heating unit sandwiched in the flow direction of the measurement target fluid, for detecting the temperature of the measurement target fluid,
    A first flow rate calculation unit that calculates the flow rate of the fluid to be measured from the difference between the output values of the temperature detection units arranged on both sides of the heating unit,
    A second flow rate calculation unit for calculating the flow rate of the fluid to be measured from the output value of the temperature detection unit arranged on one side of the heating unit,
    Equipped with
    When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated by the second flow rate calculation unit is output, and the range of the flow rate of the measurement target fluid is the predetermined condition. Even when satisfying, the deviation between the flow rate of the measurement target fluid calculated by the first flow rate calculation unit and the flow rate of the measurement target fluid calculated by the second flow rate calculation unit is a predetermined value or more. In this case, an output control unit that outputs the flow rate of the measurement target fluid calculated by the first flow rate calculation unit,
    A flow measuring device, further comprising:
  2. 　前記所定の条件は、前記流量が所定の中流量～大流量の領域に属することであることを特徴とする、請求項１に記載の流量測定装置。 The flow rate measuring device according to claim 1, wherein the predetermined condition is that the flow rate belongs to a predetermined medium to large flow rate region.
  3. 　前記第一流量算出部は、
    　前記加熱部の両側に配置された温度検出部の出力値の差分を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第一補正演算部と、
    　前記加熱部の両側に配置された温度検出部の出力値の差分を、多項式演算することで、流量を算出する第一多項式演算部と、を有し、
    　前記第二流量算出部は、
    　前記加熱部の片側に配置された温度検出部の出力値を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第二補正演算部を有し、
    　前記出力制御部は、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合において、前記第一流量算出部が前記第一多項式演算部によって算出した前記測定対象流体の流量と、前記第二流量算出部が前記第二補正演算部によって算出した前記測定対象流体の流量との間の偏差が前記所定値以上の場合には、前記第一流量算出部が算出した前記測定対象流体の流量を出力することを特徴とする、請求項１または２に記載の流量測定装置。     The first flow rate calculation unit,
    The difference between the output values of the temperature detection units arranged on both sides of the heating unit is corrected and calculated by using a conversion data table including conversion data set corresponding to a predetermined number of difference values, thereby determining the flow rate. A first correction calculation unit for calculating,
    A difference between the output values of the temperature detection units arranged on both sides of the heating unit, a first polynomial calculation unit for calculating a flow rate by performing a polynomial calculation,
    The second flow rate calculation unit,
    The flow rate is calculated by correcting the output value of the temperature detecting unit arranged on one side of the heating unit using a conversion data table including conversion data set corresponding to a predetermined number of difference values. Has a second correction calculation unit,
    The output control unit, when the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated by the first polynomial calculation unit by the first flow rate calculation unit, and When the deviation between the flow rate of the fluid to be measured calculated by the second correction calculation section by the second flow rate calculation section is equal to or more than the predetermined value, the measurement target calculated by the first flow rate calculation section The flow rate measuring device according to claim 1 or 2, wherein the flow rate of the fluid is output.
  4. 　測定対象流体を加熱する加熱部と、
    　前記加熱部の両側に該加熱部を前記測定対象流体の流れ方向に挟んで配置され、前記測定対象流体の温度を検出する複数の温度検出部と、
    　前記温度検出部の出力値より測定対象流体の流量を算出する流量算出部と、
    　を備え、流路を流れる測定対象流体の流量を検出する流量測定装置の制御方法であって、
    　前記加熱部の両側に配置された温度検出部の出力値の差分より測定対象流体の流量を算出する第一流量算出ステップと、
    　前記加熱部の片側に配置された温度検出部の出力値より前記測定対象流体の流量を算出する第二流量算出ステップと、
    　前記測定対象流体の流量が所定の条件を満たす場合には、前記第二流量算出ステップにより算出された前記測定対象流体の流量を出力するとともに、前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合であっても、前記第一流量算出ステップにおいて算出した前記測定対象流体の流量と、前記第二流量算出ステップにおいて算出した前記測定対象流体の流量との間の偏差が所定値以上の場合には、前記第一流量算出ステップにおいて算出した前記測定対象流体の流量を出力する出力ステップと、
    　を有することを特徴とする、流量測定装置の制御方法。     A heating unit for heating the fluid to be measured,
    A plurality of temperature detection units arranged on both sides of the heating unit with the heating unit sandwiched in the flow direction of the measurement target fluid, for detecting the temperature of the measurement target fluid,
    A flow rate calculation unit that calculates the flow rate of the fluid to be measured from the output value of the temperature detection unit,
    A method of controlling a flow rate measuring device, comprising:
    A first flow rate calculating step of calculating the flow rate of the fluid to be measured from the difference between the output values of the temperature detecting sections arranged on both sides of the heating section,
    A second flow rate calculating step of calculating the flow rate of the fluid to be measured from the output value of the temperature detecting section arranged on one side of the heating section,
    When the flow rate of the measurement target fluid satisfies a predetermined condition, the flow rate of the measurement target fluid calculated in the second flow rate calculation step is output, and the range of the flow rate of the measurement target fluid is the predetermined range. Even when the condition is satisfied, the deviation between the flow rate of the measurement target fluid calculated in the first flow rate calculation step and the flow rate of the measurement target fluid calculated in the second flow rate calculation step is equal to or more than a predetermined value. In the case of, an output step of outputting the flow rate of the measurement target fluid calculated in the first flow rate calculation step,
    A method for controlling a flow rate measuring device, comprising:
  5. 　前記所定の条件は、前記流量が所定の中流量～大流量の領域に属することであることを特徴とする、請求項４に記載の流量測定装置の制御方法。 The method for controlling a flow rate measuring device according to claim 4, wherein the predetermined condition is that the flow rate belongs to a predetermined medium to large flow rate region.
  6. 　前記第一流量算出ステップは、
    　前記加熱部の両側に配置された温度検出部の出力値の差分を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第一補正演算工程と、
    　前記加熱部の両側に配置された温度検出部の出力値の差分を、多項式演算することで、流量を算出する第一多項式演算工程と、を選択可能に有し、
    　前記第二流量算出ステップは、
    　前記加熱部の片側に配置された温度検出部の出力値を、所定数の差分の値に対応して設定された変換データを含む変換データテーブルを用いて補正演算することで、流量を算出する第二補正演算工程を有し、
    　前記出力ステップでは、
    　前記測定対象流体の前記流量の範囲が前記所定の条件を満たす場合において、前記第一流量算出ステップにおいて前記第一多項式演算工程によって算出した前記測定対象流体の流量と、前記第二流量算出ステップにおいて前記第二補正演算工程によって算出した前記測定対象流体の流量との間の偏差が前記所定値以上の場合には、前記第一流量算出ステップにおいて前記第一多項式演算工程によって算出した前記測定対象流体の流量を出力することを特徴とする、請求項４または５に記載の流量測定装置の制御方法。     The first flow rate calculation step,
    The difference between the output values of the temperature detection units arranged on both sides of the heating unit is corrected and calculated by using a conversion data table including conversion data set corresponding to a predetermined number of difference values, thereby determining the flow rate. A first correction calculation step for calculating,
    The difference between the output values of the temperature detection units arranged on both sides of the heating unit, by performing a polynomial calculation, a first polynomial calculation step of calculating the flow rate, and having a selectable,
    The second flow rate calculation step,
    The flow rate is calculated by correcting the output value of the temperature detecting unit arranged on one side of the heating unit using a conversion data table including conversion data set corresponding to a predetermined number of difference values. Has a second correction calculation step,
    In the output step,
    When the range of the flow rate of the measurement target fluid satisfies the predetermined condition, the flow rate of the measurement target fluid calculated by the first polynomial calculation step in the first flow rate calculation step, and the second flow rate calculation If the deviation from the flow rate of the fluid to be measured calculated in the second correction calculation step in the step is not less than the predetermined value, it is calculated in the first polynomial calculation step in the first flow rate calculation step. The control method of the flow rate measuring device according to claim 4, wherein the flow rate of the fluid to be measured is output.
PCT/JP2019/039642 2018-10-17 2019-10-08 Flow rate measuring device, and method for controlling flow rate measuring device WO2020080189A1 (en)

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Publication number Priority date Publication date Assignee Title
JP2001249040A (en) * 2000-03-06 2001-09-14 Omron Corp Fluid detecting sensor and its manufacturing method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001249040A (en) * 2000-03-06 2001-09-14 Omron Corp Fluid detecting sensor and its manufacturing method

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