阅读说明：本技术 流量测量装置、具备流量测量装置的燃气表及用于燃气表的流量测量装置单元 (Flow rate measuring device, gas meter provided with flow rate measuring device, and flow rate measuring device unit for gas meter ) 是由 山本克行 于 2020-03-04 设计创作，主要内容包括：本发明具备对测量对象流体进行加热的加热部和对测量对象流体的温度进行检测的温度检测部,基于温度检测部的检测值随时间经过的变化趋势,对在主流路上流动的测量对象流体的流量进行修正。(The present invention includes a heating unit that heats a fluid to be measured and a temperature detection unit that detects a temperature of the fluid to be measured, and corrects a flow rate of the fluid to be measured flowing through a main flow path based on a trend of a change in a detection value of the temperature detection unit with time.)

1. A flow rate measurement device for detecting a flow rate of a fluid to be measured flowing through a main flow path, comprising:

a heating unit that heats a fluid to be measured;

a temperature detection unit that detects a temperature of the fluid to be measured;

and a flow rate correction unit that corrects the flow rate of the fluid to be measured flowing through the main flow path based on a change tendency of the detection value of the temperature detection unit with the passage of time.

2. The flow measuring device of claim 1,

the flow rate correction unit includes a correction unit that corrects the flow rate of the fluid to be measured flowing through the main path based on a first elapsed period from the start of heating of the fluid to be measured to the start of heating until the detected value exceeds a first predetermined ratio of a heat equilibrium temperature of the heated fluid to be measured in the vicinity of the temperature detection unit.

3. The flow measuring device of claim 1,

the flow rate correction unit includes a correction unit that corrects the flow rate of the fluid to be measured flowing through the main path based on a slope of a temporal change when the detected value reaches a second predetermined proportion of a heat equilibrium temperature of the heated fluid to be measured in the vicinity of the temperature detection unit from the start of heating the fluid to be measured.

4. A flow measuring device according to claim 2 or 3,

the flow rate correction unit includes a correction unit that corrects the flow rate of the measurement target fluid flowing through the main path based on a second elapsed period from when heating of the measurement target fluid is stopped until the detected value of the thermal equilibrium temperature becomes lower than a third predetermined ratio of the thermal equilibrium temperature.

5. The flow measuring device of claim 1,

the flow rate correction unit includes a correction unit that corrects the flow rate of the measurement target fluid flowing through the main path based on the detection value at a time when a third elapsed period has elapsed since the start of heating the measurement target fluid.

6. A flow measuring device according to any one of claims 1 to 5,

the flow rate correction unit acquires information indicating a change tendency of the detection value with time to correct the flow rate of the measurement target fluid flowing through the main path when the flow of the measurement target fluid is in a stopped state.

7. A flow measuring device according to any one of claims 1 to 6,

the heating portion and the temperature detection portion are arranged in a direction crossing a flow direction of the fluid to be measured.

8. The flow measuring device of claim 7,

the temperature detection unit includes a plurality of temperature detection units, and at least two of the temperature detection units are arranged at positions across the heating unit.

9. Flow measuring device according to claim 7 or 8,

the temperature detection unit includes a cold junction located on an upstream side with respect to a flow direction of the fluid to be measured, and a warm junction located on a downstream side with respect to the flow direction of the fluid to be measured.

10. A flow rate measurement unit is characterized by comprising:

a flow rate measuring device according to any one of claims 1 to 9;

a display unit that displays the flow rate corrected by the flow rate correction unit;

and an integrated control unit that controls the flow rate measurement device and the display unit.

11. A gas meter is characterized by comprising:

a flow rate measuring device according to any one of claims 1 to 9;

a display unit that displays the flow rate measured by the flow rate measurement device;

an integrated control unit that controls the flow rate measurement device and the display unit;

a power supply unit that supplies power to the flow rate measuring device, the display unit, and the integrated control unit;

a housing capable of housing the flow rate measurement device, the display unit, and the integrated control unit;

and an operation unit capable of performing setting relating to an operation of the flow rate measurement device from outside the casing.

Technical Field

The present invention relates to a flow rate measurement device, a gas meter provided with the flow rate measurement device, and a flow rate measurement device unit used for the gas meter.

Background

Conventionally, a measuring apparatus has been proposed which includes a heater and a sensor, and calculates a flow velocity or a flow rate of a fluid by detecting a temperature distribution that changes with the flow of the fluid with the sensor.

Further, a flow rate measurement device has been proposed in which a heating unit and a temperature detection unit are arranged in a direction orthogonal to the flow direction of a fluid to be measured, and the flow rate detection unit is arranged at a position other than a physical energy value detection flow path (for example, see patent document 1).

In the conventional flow rate measurement device as described above, the flow rate dependency can be dealt with by providing the physical property value detection sections arranged in a direction orthogonal to the flow direction of the fluid to be measured. However, when the composition or the kind of the fluid to be measured is similar, it may be difficult to suppress the flow rate dependency.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012-233776

Disclosure of Invention

The present invention has been made in view of the above problems, and an object thereof is to provide a technique for measuring a flow rate in a flow rate measuring apparatus with further improved accuracy.

In order to solve the above problem, a flow rate measurement device according to the present invention is a flow rate measurement device for detecting a flow rate of a measurement target fluid flowing through a main flow path, the flow rate measurement device including:

a heating unit that heats a fluid to be measured;

a temperature detection unit that detects a temperature of the fluid to be measured;

and a flow rate correction unit that corrects the flow rate of the fluid to be measured flowing through the main flow path based on a change tendency of the detection value of the temperature detection unit with the passage of time.

According to the flow rate measuring device, the output of the temperature detecting unit can be controlled to have an influence due to physical properties of fluids having similar compositions or types based on a trend of change with the passage of time from the start of heating of the fluid to be measured, and an accurate flow rate that is less affected by flow rate dependency can be output.

In the present invention, the flow rate correction unit may include correction means for correcting the flow rate of the fluid to be measured flowing through the main path based on a first elapsed period from the start of heating of the fluid to be measured to a point at which the detected value exceeds a first predetermined proportion of a heat equilibrium temperature of the heated fluid to be measured in the vicinity of the temperature detection unit.

Here, the first predetermined ratio is an index indicating a relative degree of the heat balance of the fluid heated by the heating unit to the outputs of the plurality of temperature detection units during the heating period, for example, as 100%. As described above, by correcting the flow rate of the fluid to be measured based on the first elapsed time from the start of heating of the fluid to be measured until the output of the temperature detection unit exceeds the first predetermined ratio of the heat equilibrium temperature of the heated fluid to be measured, it is possible to output a flow rate in which the dependency on the physical properties on the influence of the thermal diffusion of the fluid having an approximate composition or kind is reduced.

In the present invention, the flow rate correction unit may include correction means for correcting the flow rate of the fluid to be measured flowing through the main path based on a slope of a change with time from the start of heating the fluid to be measured when the detected value reaches a second predetermined proportion of a heat equilibrium temperature of the heated fluid to be measured in the vicinity of the temperature detection unit.

Here, the second predetermined ratio is an index indicating the relative degree of the heat balance of the fluid heated by the heating unit to the outputs of the plurality of temperature detection units during the heating period, which is 100% as in the first predetermined ratio. As described above, by correcting the output of the temperature detection unit based on the slope of the change with time from the start of heating the fluid to be measured to the time when the output reaches the second predetermined ratio of the thermal equilibrium temperature of the heated fluid to be measured, it is possible to output a flow rate in which the dependency on the physical properties on the thermal diffusion influence of the fluids having similar compositions or types is reduced.

In the present invention, the flow rate correction unit may include correction means for correcting the flow rate of the fluid to be measured flowing through the main path based on a second elapsed period from when heating of the fluid to be measured is stopped until the detected value of the heat equilibrium temperature becomes lower than a third predetermined proportion of the heat equilibrium temperature.

Here, the third predetermined ratio is an index indicating the relative degree, which represents the thermal equilibrium state as 100% as in the first predetermined ratio. As described above, by correcting the fluid in which the supply of heat is stopped by stopping the heating of the fluid to be measured based on the second elapsed period until the output of the temperature detection unit becomes lower than the third predetermined proportion of the heat equilibrium temperature, it is possible to output a flow rate in which the dependency of the physical properties on the influence of the thermal diffusion of the fluid is reduced.

In the present invention, the flow rate correction unit may include correction means for correcting the flow rate of the fluid to be measured flowing through the main path based on the detection value at a time point when a third elapsed period has elapsed since the start of heating the fluid to be measured. This allows the flow rate of the fluid to be measured flowing through the main path to be directly corrected based on the output of the temperature detection unit at the time when the third elapsed period has elapsed. As a result, the load on the arithmetic device can be reduced, and higher-speed processing can be realized.

In the present invention, the flow rate correction unit may acquire information indicating a change tendency of the detection value with time to correct the flow rate of the measurement target fluid flowing through the main path when the flow of the measurement target fluid is in a stopped state. This can suppress flow rate dependency of physical properties that affect thermal diffusion of the fluid, and therefore can improve the accuracy of flow rate measurement.

In the present invention, the heating unit and the temperature detection unit may be arranged in a direction crossing a flow direction of the fluid to be measured. In addition, the temperature detection unit may be provided in plurality, and at least two of the temperature detection units may be arranged at positions across the heating unit. The temperature detection unit may include a cold junction located upstream in the flow direction of the fluid to be measured, and a warm junction located downstream in the flow direction of the fluid to be measured. Even with such a configuration, the flow rate dependency of the physical properties that affect the thermal diffusion of the fluid can be suppressed, and the accuracy of the flow rate measurement can be improved.

The flow rate measurement unit of the present invention may further include:

the flow rate measuring device described above;

a display unit that displays the flow rate corrected by the flow rate correction unit;

and an integrated control unit that controls the flow rate measurement device and the display unit.

In this way, a gas meter capable of outputting and displaying the flow rate of the fluid to be measured can be manufactured more easily or efficiently.

Further, the gas meter of the present invention may include:

the flow rate measuring device described above;

a display unit that displays the flow rate measured by the flow rate measurement device;

an integrated control unit that controls the flow rate measurement device and the display unit;

a power supply unit that supplies power to the flow rate measuring device, the display unit, and the integrated control unit;

a housing capable of housing the flow rate measurement device, the display unit, and the integrated control unit;

and an operation unit capable of performing setting relating to an operation of the flow rate measurement device from outside the casing.

Thus, a gas meter capable of measuring flow with higher accuracy can be provided.

Effects of the invention

According to the present invention, in the flow rate measuring apparatus, flow rate measurement with higher accuracy can be performed.

Drawings

Fig. 1 is an exploded perspective view showing an example of a flow rate measurement device according to embodiment 1 of the present invention.

Fig. 2 is a cross-sectional view showing an example of a flow rate measuring device according to example 1 of the present invention.

Fig. 3 is a plan view showing a sub-flow path portion in example 1 of the present invention.

Fig. 4 is a perspective view showing an example of a sensor element according to embodiment 1 of the present invention.

Fig. 5 is a sectional view for explaining the composition of the sensor element of embodiment 1 of the present invention.

Fig. 6 is a plan view showing a schematic configuration of a flow rate detecting unit according to example 1 of the present invention.

Fig. 7 is a plan view showing a schematic configuration of a physical property value detection section in example 1 of the present invention.

Fig. 8 is a block diagram showing a functional configuration of a circuit board according to embodiment 1 of the present invention.

Fig. 9 is a graph showing the relationship between each fluid and the transition time for each fluid to reach a thermal equilibrium state.

Fig. 10 is a graph showing a relationship between a rise time and a thermal conductivity of each fluid.

Fig. 11 is a flowchart of flow measurement processing of embodiment 1 of the present invention.

Fig. 12 is a flowchart of flow measurement processing of embodiment 2 of the present invention.

Fig. 13 is a flowchart of flow measurement processing of embodiment 3 of the present invention.

Fig. 14 is a flowchart of flow measurement processing of embodiment 4 of the present invention.

Fig. 15 is a block diagram showing a functional configuration of a gas meter according to embodiment 5 of the present invention.

Detailed Description

(application example)

Hereinafter, an application example 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 measurement device 1 shown in fig. 1. As shown in fig. 2, the flow rate measurement device 1 branches a fluid flowing through the main channel portion 2, introduces a part of the fluid into the flow rate detection portion 11, and measures a flow rate in the flow rate detection portion 11 having a high correlation with the flow rate of the fluid in the main channel portion 2. As shown in fig. 4, the sensor element used in the flow rate detection unit 11 has a structure in which two temperature detection units 102 are arranged with a micro heater (heating unit) 101 interposed therebetween.

As a measurement principle, when there is no flow of the fluid, the temperature distribution around the micro-heater 101 is substantially uniform as shown in fig. 5 (a). On the other hand, for example, in the case where the fluid flows in the direction indicated by the broken-line arrow in fig. 5B, the unheated fluid moves, and therefore, the temperature on the downstream side becomes higher than on the upstream side of the micro-heater 101. In this way, the correlation between the temperature difference Δ T between the temperatures detected by the two temperature detection portions 102 and the flow rate of the fluid passing therethrough, which is caused by the variation in the distribution of the heater heat, is utilized.

As shown in fig. 8, which is a functional block of the flow rate measurement device 1, the output of the flow rate detection unit 11 is sent to a detection value acquisition unit 131 of the control unit 13 implemented by a cpu (central Processing unit) disposed on the circuit board 5, and after necessary correction or the like is performed in the flow rate calculation unit 133, the flow rate as the final output is calculated.

However, when the composition or the type of the fluid to be measured is similar, the fluid having the similar composition or the similar type may be included in a predetermined range of the temperature difference Δ T between the temperatures detected by the two temperature detectors 102. For example, when a fluid in which a plurality of substances having close specific heat values are mixed is measured, it is difficult to suppress flow rate dependency from the correction performed by the flow rate calculation unit 133 because it depends on physical characteristics such as the mass of the fluid and the ease of movement.

However, as shown in fig. 9, it is understood that the transient response characteristic accompanying the lapse of time from the start of heating of the micro-heater 101 to the thermal equilibrium state has a correlation with the physical properties of the constituent fluid. As shown in fig. 10, it is understood that the rise time from the start of heating to the thermal equilibrium state has a correlation with the physical properties of the fluid. Here, the physical properties of the fluid are, for example, properties relating to thermal diffusion such as thermal conductivity, specific heat, viscosity, and density.

In view of the above, the present invention includes a flow rate correction unit that corrects the flow rate of the fluid to be measured flowing through the main flow path based on the trend of changes in the outputs of the plurality of temperature detection units with time. This makes it possible to perform correction based on transient response characteristics associated with the elapse of time from the start of heating to a thermal equilibrium state, thereby suppressing the influence of physical properties of fluids having similar compositions or types, and outputting an accurate flow rate that is less susceptible to the influence of flow rate dependency.

The present invention can be applied to the thermal type flow rate measurement device 1 as described above, and can also be applied to a gas meter 150 shown in fig. 15 including the flow rate measurement device 1. The gas meter 150 includes a display unit 151, a power supply unit 152, an operation unit 153, a vibration detection unit 154, a shutoff unit 155, a gas meter control unit 156, a gas meter storage unit 157, and a gas meter communication unit 158, in addition to the flow rate measurement device 1.

In fig. 15, the present invention can be applied to a flow rate measurement device unit 150a in which elements including the flow rate measurement device 1, the display unit 151, the power supply unit 152, and the gas meter control unit 156 are unitized and which is easily assembled when manufacturing the gas meter 150.

(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.

(device construction)

Fig. 1 is an exploded perspective view showing an example of a flow rate measurement device 1 according to the present embodiment. Fig. 2 is a cross-sectional view showing an example of the flow rate measurement device 1. The flow rate measurement device 1 is incorporated in, for example, a gas meter, a combustion device, an internal combustion engine such as an automobile, a fuel cell, other industrial equipment such as medical equipment, or an assembly device, and measures the amount of fluid passing through a flow path. The arrows of the broken lines in fig. 1 and 2 illustrate the flow direction of the fluid.

As shown in fig. 1, a flow rate measuring device 1 of 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 2, in the present embodiment, the flow rate measurement device 1 includes a sub-flow path portion 3 branched from a main flow path portion 2. The secondary flow path section 3 includes a flow rate detection section 11 and a physical energy value detection section 12. The flow rate detection unit 11 and the physical energy value detection unit 12 are each constituted by a thermal flow rate sensor including a heating unit formed by a micro heater and a temperature detection unit formed by a thermopile. In the present embodiment, the physical property value of the fluid is detected by the physical property value detecting section 12, and the flow rate detected by the flow rate detecting section 11 is corrected based on the physical property value of the fluid, but the flow rate measuring device 1 may not include the physical property value detecting section 12.

The main channel section 2 is a tubular member through which a channel of a fluid to be measured (hereinafter also referred to as a main channel) passes in a longitudinal direction. As shown in fig. 2, an inlet port (first inlet port) 34A is formed on the upstream side and an outlet port (first outlet port) 35A is formed on the downstream side with respect to the fluid flow direction on the inner peripheral surface of the main channel portion 2. For example, the axial length of the main channel portion 2 is about 50mm, the diameter of the inner peripheral surface (the inner diameter of the main channel portion 2) is about 20mm, and the outer diameter of the main channel portion 2 is about 24mm, but the size of the main channel portion 2 is not limited thereto. In the main channel portion 2, an orifice 21 is provided between the inflow port 34A and the outflow port 35A. The orifice 21 is a resistance body having an inner diameter smaller than that of the front and rear sides of the main flow path portion 2, and the amount of fluid flowing into the sub flow path portion 3 can be adjusted according to the size of the orifice 21.

In fig. 1 and 2, a sub-flow path portion 3, which is a portion including a sub-flow path branched from a main flow path, is provided vertically above the main flow path portion 2. The sub-channel in the sub-channel section 3 includes an inflow channel 34, a physical energy value detection channel 32, a flow rate detection channel 33, and an outflow channel 35. A part of the fluid flowing through the main channel 2 branches and flows into the sub channel 3.

The inflow channel 34 is a channel for allowing the fluid flowing through the main channel section 2 to flow therein and to be branched into the physical property value detection channel 32 and the flow rate detection channel 33. The inflow channel 34 is formed in a direction perpendicular to the flow direction of the fluid in the main channel portion 2, and has one end communicating with the inflow port 34A and the other end communicating with the physical energy value detection channel 32 and the flow rate detection channel 33. A part of the fluid flowing through the main channel section 2 is further branched into the physical property value detection channel 32 and the flow rate detection channel 33 via the inflow channel 34. In the physical property value detection flow path 32 and the flow rate detection flow path 33, a fluid of an amount corresponding to the amount of the fluid flowing through the main flow path section 2 flows. Therefore, the flow rate detecting unit 11 can detect a value corresponding to the amount of the fluid flowing through the main channel unit 2.

As shown in fig. 1, the physical property value detection flow channel 32 is a flow channel formed vertically above the main flow channel section 2, extending in a direction parallel to the main flow channel section 2, and having a substantially U-shaped cross section when viewed from above. The physical property value detection flow path 32 has a physical property value detection section 12 disposed therein for detecting a physical property value of the fluid to be measured. One end of the physical property value detection channel 32 communicates with the inlet 34A via the inflow channel 34, and the other end communicates with the outlet 35A via the outflow channel 35.

The flow rate detection flow path 33 is also a flow path extending in a direction parallel to the flow direction of the fluid in the main flow path portion 2 and having a substantially U-shaped cross section when viewed from above. A flow rate detection unit 11 for detecting the flow rate of the fluid is disposed in the flow rate detection flow path 33. One end of the flow rate detection channel 33 communicates with the inlet 34A via the inflow channel 34, and the other end communicates with the outlet 35A via the outflow channel 35. The physical energy value detection unit 12 and the flow rate detection unit 11 are mounted on the circuit board 5, respectively. The circuit board 5 is disposed so as to cover the upper portions of the physical property value detection flow path 32 and the flow rate detection flow path 33, which have openings at the upper portions, and the physical property value detection section 12 is located in the physical property value detection flow path 32 and the flow rate detection section 11 is located in the flow rate detection flow path 33.

The outflow channel 35 is a channel for allowing the fluid to be measured, which 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 channel 35 is formed in a direction perpendicular to the main channel section 2, and has one end communicating with the outflow port 35A and the other end communicating with the physical property value detection channel 32 and the flow rate detection channel 33. The fluid to be measured 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 section 2 through the outflow flow path 35.

In the present embodiment, as described above, the fluid to be measured flowing in from the one inflow port 34A is branched into the physical property value detection flow path 32 and the flow rate detection flow path 33. Thus, 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 fluid having the conditions such as temperature and density that are substantially equal to each other. In the flow rate measuring device 1, the sealing member 4 is fitted into the sub-flow path portion 3, the circuit board 5 is disposed, and the circuit board 5 is fixed to the sub-flow path portion 3 by the cover 6, thereby ensuring airtightness inside the sub-flow path portion 3.

Fig. 3 is a plan view of the secondary flow path portion 3 shown in fig. 1. 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 position of the central axis of the inflow flow path 34 and the position of the central axis of the outflow flow path 35 in a plan view. Arrows P and Q schematically show the ratio of the flow rate of the fluid that has been branched into the physical property value detection flow path 32 and the flow rate detection flow path 33. In the present embodiment, the cross-sectional areas of the physical property value detection flow path 32 and the flow rate detection flow path 33 are determined so that the amount of the fluid to be branched is the ratio of P to Q.

In practice, the amount of fluid flowing through the physical property value detection flow path 32 and the flow rate detection flow path 33 varies depending on the flow rate of fluid flowing through the main flow path section 2, but in a normal usage mode, the size of the sub flow path section 3 with respect to the main flow path section 2, the size of the orifice 21, and the widths of the physical property value detection flow path 32 and the flow rate detection flow path 33 are set so that the amount of fluid flowing through the physical property value detection flow path 32 is a value within the detection range of the physical property value detection section 12, and the amount of fluid flowing through the flow rate detection flow path 33 is a value within the detection range of the flow rate detection section 11, respectively. The widths of the physical property value detection flow path 32 and the flow rate detection flow path 33 are examples, and are not limited to the example shown in fig. 3.

In this way, in the flow rate measuring apparatus 1, the flow rates of the fluids branched to the physical property value detection flow path 32 and the flow rate detection flow path 33 can be controlled by adjusting the respective widths. Therefore, the flow rate of the fluid flowing through the physical property value detection flow path 32 can be controlled according to the detection range of the physical property value detection unit 12, and the flow rate of the fluid flowing through the flow rate detection flow path 33 can be controlled according to the detection range of the flow rate detection unit 11.

The physical property value detection flow path 32 and the flow rate detection flow path 33 are not limited to those which are formed in a substantially U-shape in plan view. That is, the physical property value detection flow path 32 and the flow rate detection flow path 33 may have other shapes as long as the widths (cross-sectional areas) of the flow rates of the fluids passing through the physical property value detection flow path 32 and the flow rate detection flow path 33 are controllable.

In addition, in the physical property value detection flow path 32 and the flow rate detection flow path 33, the shape of the space in which the physical property value detection section 12 and the flow rate detection section 11 are arranged is substantially square in a plan view, but the present invention is not limited thereto. The shapes of the physical property value detection channel 32 and the flow rate detection channel 33 may be determined according to the shapes of the physical property value detection section 12 and the flow rate detection section 11, and the like, as long as the physical property value detection section 12 and the flow rate detection section 11 can be arranged.

Therefore, for example, when the size of the physical property value detection section 12 is smaller than the width of the physical property value detection flow path 32, the width of the space in which the physical property value detection section 12 is arranged in the physical property value detection flow path 32 may be made equal to the width of the other part of the physical property value detection flow path 32. That is, in this case, the portion extending in the longitudinal direction of the physical property value detection flow channel 32 has a substantially constant width. The same applies to the flow rate detection flow path 33.

As described above, the amount of the fluid flowing through the physical property value detection flow path 32 and the flow rate detection flow path 33 is smaller than the amount of the fluid flowing through the main flow path section 2, but varies depending on the amount of the fluid flowing through the main flow path section 2. If the flow rate detection unit 11 and the physical property value detection unit 12 are disposed in the main channel unit 2, the flow rate detection unit 11 and the physical property value detection unit 12 need to be increased in scale according to the amount of fluid flowing through the main channel unit 2. However, in the present embodiment, by providing the sub-channel portion 3 branched from the main channel portion 2, the flow rate of the fluid can be measured by the small-scale flow rate detection portion 11 and the physical property value detection portion 12.

In the present embodiment, the cross-sectional area of the physical property value detection flow path 32 is smaller than the cross-sectional area of the flow rate detection flow path 33, and as indicated by the size of arrows P and Q in fig. 3, the amount of fluid flowing through the physical property value detection flow path 32 is smaller than the amount of fluid flowing through the flow rate detection flow path 33. By reducing the amount of fluid flowing through the physical property value detection unit 12 as compared with the amount of fluid flowing through the flow rate detection unit 11 in this way, it is possible to reduce errors caused by the influence of the flow rate when the physical property value detection unit 12 detects the physical property value or the temperature of the fluid.

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 sectional view for explaining the composition 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 temperature detection units) 102 symmetrically disposed with the micro-heater 101 interposed therebetween. That is, the micro-heater 101 and the two thermopiles 102 are arranged in a predetermined direction. On the top and bottom of these, as shown in fig. 5, an insulating film 103 is formed, and the micro-heater 101, the thermopile 102, and the insulating film 103 are provided on a silicon base 104. Further, a cavity (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 a resistor formed of, for example, polysilicon. In fig. 5, the temperature distribution when the micro-heater 101 generates heat is schematically shown by a dotted ellipse. The thicker the broken line, the higher the temperature. When there is no fluid flow, the temperature distribution around the micro-heater 101 is substantially uniform as shown in fig. 5 (a). On the other hand, for example, in the case where the fluid flows in the direction indicated by the arrow of the broken line in fig. 5(b), the fluid moves, and therefore, the unheated fluid flows into the upstream side of the micro-heater 101, and the temperature of the downstream side becomes higher than that of the upstream side of the micro-heater 101. The sensor element 100 outputs a value indicating a flow rate by using such a deviation of the heater heat distribution.

The output voltage Δ V of the sensor element is represented by, for example, the following equation (1).

Further, Th is a temperature of the micro-heater 101 (a temperature of an end portion on the micro-heater 101 side in the thermopile 102), Ta is a lower one of temperatures of an end portion on the side away from the micro-heater 101 in the thermopile 102 (a temperature on the left side in the left thermopile 102 in fig. 5 a), Ta is a lower one of temperatures of an end portion on the side away from the micro-heater 101 in the thermopile 102 (a temperature on the left end on the left side in fig. 5a or a temperature on the right end on the right side in the thermopile 101 side in fig. 5b, a temperature on the left end of the left thermopile 102 as an end portion on the upstream side in fig. 5 b), Vf is an average value of flow rates, and a and b are predetermined constants.

The circuit board 5 of the flow rate measurement device 1 includes a control unit (not shown) implemented by an ic (integrated circuit) or the like, and calculates the flow rate from the output of the flow rate detection unit 11. The circuit board 5 may calculate a predetermined characteristic value from the output of the physical property value detection unit 12 and correct the flow rate using the characteristic value.

(flow rate detecting section and physical energy value detecting section)

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. 1. As shown in fig. 6, the flow rate detector 11 includes: a first thermopile (also referred to as a temperature detecting unit) 111 and a second thermopile (also referred to as a temperature detecting unit) 112 that detect the temperature of a fluid to be measured, and a micro-heater (also referred to as a heating unit) 113 that heats the fluid to be measured. The heating unit 113, the temperature detection unit 111, and the temperature detection unit 112 are arranged in the flow detection unit 11 along the flow direction P of the fluid to be measured. The heating unit 113, the temperature detection unit 111, and the temperature detection unit 112 are each substantially rectangular in shape in plan view, and the longitudinal direction thereof is perpendicular to the flow direction P of the fluid to be measured.

Of the temperature detection unit 111 and the temperature detection unit 112, the temperature detection unit 112 is disposed upstream of the heating unit 113, and the temperature detection unit 111 is disposed downstream, and detects temperatures at positions symmetrical across the heating unit 113.

In the flow rate measuring apparatus 1, the sensor element 100 having substantially the same configuration is used for the physical property value detecting section 12 and the flow rate detecting section 11. The sensor element 100 of the physical property value detection unit 12 and the sensor element 100 of the flow rate detection unit 11 are arranged such that the arrangement angle with respect to the flow direction of the fluid differs by 90 degrees in a plan view of the sensor element 100. Accordingly, the sensor elements 100 having the same configuration can be used for the physical property value detection unit 12 and the flow rate detection unit 11, and the manufacturing cost of the flow rate measurement device 1 can be reduced.

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 that heats the fluid to be measured. The heating unit 123, the temperature detection unit 121, and the temperature detection unit 122 are arranged in the physical property value detection unit 12 in a direction orthogonal to the flow direction Q of the fluid to be measured. The heating unit 123, the temperature detection unit 121, and the temperature detection unit 122 are each substantially rectangular in shape in plan view, and the longitudinal direction thereof is along the flow direction Q of the fluid to be measured. The temperature detection units 121 and 122 are disposed symmetrically with respect to the heating unit 123, and detect the temperatures of symmetrical positions on both sides of the heating unit 123. Therefore, the measurement values of the temperature detector 121 and the temperature detector 122 are substantially the same, and an average value or one of the values may be used.

Here, since the temperature distribution is shifted to the downstream side by the flow of the fluid, the change in the temperature distribution in the direction orthogonal to the flow direction is smaller than the change in the temperature distribution in the flow direction of the fluid. Therefore, by arranging the temperature detection unit 121, the heating unit 123, and the temperature detection unit 122 in this order in a direction orthogonal to the flow direction of the fluid to be measured, it is possible to reduce the change in the output characteristics of the temperature detection unit 121 and the temperature detection unit 122 due to the change in the temperature distribution. Therefore, the influence of the change in the temperature distribution due to the flow of the fluid can be reduced, and the detection accuracy of the physical property value detection unit 12 can be improved.

Further, since the longitudinal direction of the heating portion 123 is arranged along the flow direction of the fluid to be measured, the heating portion 123 can heat the fluid to be measured over a wide range of the flow direction of the fluid to be measured. Therefore, even when the temperature distribution is shifted to the downstream side by the flow of the fluid to be measured, the variation in the output characteristics of the temperature detection unit 121 and the temperature detection unit 122 can be reduced. Also, in the case of measuring the fluid temperature, the error of the measurement value due to the flow velocity can be reduced. The fluid temperature may be determined by subtracting the amount of temperature increase during heating by the heating unit 123 from the temperatures detected by the temperature detection unit 121 and the temperature detection unit 122, or may be detected in a state where the heating unit 123 is not heating. According to the physical property value detection unit 12, the influence of the change in the temperature distribution due to the flow of the fluid to be measured can be suppressed, and the detection accuracy of the physical property value and the fluid temperature can be improved.

Further, since the longitudinal directions of the temperature detector 121 and the temperature detector 122 are arranged along the flow direction of the fluid to be measured, the temperature detector 121 and the temperature detector 122 can detect the temperature over a wide range in the flow direction of the fluid to be measured. Therefore, even when the temperature distribution is shifted to the downstream side by the flow of the fluid to be measured, the variation in the output characteristics of the temperature detection unit 121 and the temperature detection unit 122 can be reduced. Therefore, the influence of the change in the temperature distribution due to the flow of the fluid to be measured can be reduced, and the detection accuracy of the physical property value detection unit 12 can be improved.

(functional Structure)

Fig. 8 is a block diagram showing an example of a functional configuration of the flow rate measurement 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, a storage unit 14, and a communication unit 15. The flow rate detector 11 includes a temperature detector 111 and a temperature detector 112. The physical property value detection unit 12 includes a temperature detection unit 121 and a temperature detection unit 122. The heating unit 113 shown in fig. 6 and the heating unit 123 shown in fig. 7 are not shown. The control unit 13 includes a detection value acquisition unit 131, a characteristic value calculation unit 132, and a flow rate calculation unit 133. The storage unit 14 includes storage media such as a flash memory, a ram (random Access memory), and a rom (read Only memory), and holds the correction table 141.

The flow rate detecting unit 11 calculates a difference between a signal corresponding to the temperature detected by the temperature detecting unit 111 and a signal corresponding to the temperature detected by the temperature detecting unit 112, and outputs the difference to the detection value acquiring 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 corresponding 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. In addition, a signal corresponding to the temperature may be acquired by using either one of the temperature detector 121 and the temperature detector 122.

The detection value acquisition unit 131 acquires a detection value corresponding to the flow rate of the fluid output from the flow rate detection unit 11 at predetermined measurement intervals. The characteristic value calculation unit 132 calculates a 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 may calculate the characteristic value by multiplying a predetermined coefficient by the temperature difference of the fluid to be measured detected by the temperature detection unit 121 or the temperature detection unit 122 before and after the change in the temperature of the micro heater of the physical property value detection unit 12.

The flow rate calculation unit 133 calculates the flow rate based on the detection value acquired by the detection value acquisition unit 131. At this time, the flow rate calculation unit 133 may correct the flow rate using the characteristic value calculated by the physical property value detection unit 12. The communication unit 15 transmits information processed by the control unit 13 to the outside in a wireless or wired manner, receives a command or a setting value from the outside in a wireless or wired manner, and transmits the command or the setting value to the control unit 13. The setting value received from the outside contains data stored in the fix-up table 141 of the storage section 14. The correction table 141 stores, for example, a correction coefficient corresponding to a measured value of the transient response characteristic.

However, the conventional flow rate calculation unit 133 calculates the volume flow rate (l/min) of the fluid based on Δ V obtained by equation (1). When there is no fluid flow, the temperature distribution around the micro-heater 101 is substantially uniform as shown in fig. 5 (a). The temperature distribution around the micro-heater 101 reaches a thermal equilibrium state according to the amount of heat supplied from the micro-heater 101 and the physical properties (thermal conductivity, specific heat, viscosity, density, etc.) of the fluid.

Fig. 9 is a graph illustrating transient response characteristics with time passing in the vicinity of a thermal equilibrium state with respect to sensor outputs SV detected by two thermopiles 102 symmetrically disposed across the micro-heater 101 from the start of heating of the micro-heater 101 to the thermal equilibrium state. In fig. 9, the vertical axis represents the output SV of the temperature detector 121 or 122 of the physical property value detector 12, and the horizontal axis represents the elapsed time (ms) from the start of heating by the heater 123. The output SV of the physical property value detection unit 12 is normalized by 100% of the sensor output value in the thermal equilibrium state. The output SV of the physical property value detection unit 12 may be the output of either the temperature detection unit 121 or the temperature detection unit 122, or may be the average of the output of the temperature detection unit 121 and the output of the temperature detection unit. Hereinafter, the output of either one of the temperature detector 121 and the temperature detector 122, and the average value of the output of the temperature detector 121 and the output of the temperature detector will be simply referred to as the output of the temperature detector 121 and the like.

As shown in fig. 9, it is understood that the elapsed time until the thermal equilibrium state is reached differs depending on the physical properties of the constituent fluid. For example, since the elapsed time until the sensor output SV reaches a value indicating 95% with respect to the thermal equilibrium state is influenced by physical properties (thermal conductivity, specific heat, viscosity, density, and the like) related to thermal diffusion of the fluid, it is known that 3 types of gas (air, city gas 13A, C12) are different from each other. In the example of fig. 9, the elapsed time t1 of air is longer than the elapsed time t2 of the city gas 13A, and the elapsed time t3 of C12 is shorter than the city gas 13A.

FIG. 10 is a graph showing the relationship between the elapsed time and the thermal conductivity λ (mW/m · K) of the 3 types of gases in FIG. 9. In fig. 10, the vertical axis represents elapsed time (ms), and the horizontal axis represents thermal conductivity. As shown in fig. 10, it is understood that the thermal conductivity is relatively lowest in the air with the longest elapsed time. Further, it is found that the thermal conductivity is relatively highest in the gas C12 in which the elapsed time is the shortest. It is understood that in the city gas 13A having the elapsed time longer than that of the gas C12 and shorter than that of the air, the thermal conductivity is relatively higher than that of the air and relatively lower than that of the gas C12. As described above, in these fluids, the longer the elapsed time from the start of heating to a predetermined ratio (95%) of the thermal equilibrium state, the lower the thermal conductivity.

Therefore, the relationship between the transient response characteristic and the thermal conductivity as described above is experimentally measured in advance, and the measurement result subjected to statistical processing such as an average value or a standard deviation distribution is held in a memory or the like as a correction table, whereby the physical property value of the fluid to be measured can be directly corrected based on the output SV from the physical property value detection unit 12 or the like. As a result, flow measurement that is less susceptible to the composition of the fluid can be performed.

As an example of the transient response characteristic, as shown in fig. 9, a sensor rise time, which is an elapsed time from the start of heater heating until the sensor output (SV) reaches a predetermined ratio of the equilibrium state, can be exemplified. Further, the gradient (Δ SV/Δ t) of the change in the sensor output (SV) in the process of passing from the start of heating of the heater to the equilibrium state may be measured as the transient response characteristic. This is because the physical property value corresponding to the kind of fluid is reflected in the slope of the change in the sensor output.

Further, as shown in the graph of fig. 9, the sensor output corresponding to a predetermined elapsed time may be measured as the transient response characteristic. Similarly, the sensor fall time, which is the elapsed time from when the heater stops heating until the sensor output (SV) falls below a predetermined ratio of the equilibrium state, may be measured as the transient response characteristic. In any case, the physical property value corresponding to the kind of the fluid is reflected in the transient response of the measurement object.

(flow rate measurement processing)

Fig. 11 is a process flowchart showing an example of flow rate measurement processing in the flow rate measurement device 1. This process is executed by sending a command from a CPU (not shown) provided in the circuit board 1 of the flow rate measurement device 1 to the flow rate detection unit 11, the physical property value detection unit 12, and the control unit 13. When this process is executed, first, in step S101, time measurement is started when the heating unit 123 of the physical property value detection unit 12 is turned on. In S102, the time (t0) is set to be the time when the application of the current for driving the heating portion 123 is started, and the elapsed time (t) is measured. If the process of S102 ends, the process proceeds to S103.

In S103, it is determined that the detected value (SV) of the temperature detector 121 or the like of the physical property value detector 12 exceeds a first predetermined ratio. Here, the first predetermined ratio is a predetermined threshold value for determining a rise time normalized by a heat balance value of the fluid to be measured. As such a first predetermined ratio, for example, a value corresponding to approximately 95% is exemplified with the thermal equilibrium value of the fluid to be measured for flow being 100%.

In the processing of S103, the output signal of the temperature detector 121 of the physical property value detector 12 or the like is transmitted to the characteristic value calculator 132 of the controller 13, and the sensor output (SV) is detected by the characteristic value calculator 132. Then, if the detected SV exceeds the first predetermined ratio (S103, yes), the process proceeds to S104, and if not (S103, no), the process proceeds to S102.

In step S104, the elapsed time is measured (t 1). When the process of S104 ends, the flow proceeds to S105. In S105, the sensor output rise time is determined. More specifically, the sensor output rise time (t2) relating to the fluid to be flow-measured is determined by the difference between the time (t1) at which the time measurement has elapsed and the time (t0) at which the time measurement started. If the process of S105 ends, the process proceeds to S106.

In S106, a characteristic correction value of the fluid to be measured is determined using a correction coefficient between a sensor rise time and a thermal conductivity (W/m · K). More specifically, the flow rate calculation unit 132 accesses the correction table 141 stored in advance in the storage unit 14 on the circuit board 5, and obtains a characteristic correction value corresponding to the sensor rise time (t 2). If the process of S106 ends, the process proceeds to S107. In S107, the flow rate calculation unit 132 performs gas correction based on the output from the characteristic value calculation unit 132 in which the characteristic correction value is reflected, as necessary, and outputs the final volume flow rate (l/min) of the fluid. When the processing in S107 ends, the present routine is once ended.

As described above, in the present embodiment, the physical property characteristic of the fluid is corrected based on the relationship between the sensor output rise time and the thermal conductivity (W/m · K) at which the normalized detection value (SV) of the temperature detection unit 121 and the like outputted from the physical property value detection unit 12 reaches the first predetermined ratio, and the volume flow rate (L/min) is outputted. Thus, the difference in physical properties due to the approximation of the composition or type of the fluid to be measured can be determined using the sensor rise time as the transient response characteristic, and flow measurement with higher accuracy can be performed without being affected by the physical properties of the fluid. Further, the correction content in the flow rate calculation unit 133 can be further simplified, and the calculation load in the control unit 13 can be reduced.

(example 2)

Next, as example 2, an example in which characteristic correction based on the slope of the rising change in the sensor output can be performed will be described. Fig. 12 is a process flow chart showing another example of the flow rate measurement process in the flow rate measurement device 1. The following processing shown in fig. 12 to 14 is performed in the same manner as in embodiment 1.

First, in step S111, time measurement is started when the heating unit 123 in the physical property value detection unit 12 is turned on, and in step S112, the elapsed time (t) is measured when the current for driving the heating unit 123 starts to be applied (t 0). In S113, it is determined that the detected value (SV) of the temperature detection unit or the like of the physical property value detection unit 12 has reached the second predetermined ratio. The second predetermined ratio is a predetermined threshold value for determining a slope of the rising change normalized by the thermal equilibrium value of the fluid to be measured. As the second predetermined ratio, for example, a value corresponding to approximately 90% is exemplified with the heat balance value of the fluid to be measured being 100%. However, the value set as the second predetermined ratio may be selected from a region in which the ratio per unit time of the rising change is approximated within the error range, for example.

In the process of S113, the output signals of the temperature detector 121 and the temperature detector 122 of the physical property value detector 12 are transmitted to the characteristic value calculator 132 of the controller 13, and the sensor output (SV) is detected by the characteristic value calculator 132. Then, when the detected sensor output (SV) reaches the second predetermined ratio (S113, yes), the process proceeds to S114, and when not (S113, no), the process proceeds to S112.

In step S114, the elapsed time is measured (t 3). In S115, the slope of the sensor output change is determined. More specifically, the slope of the change in the sensor output is determined by dividing the sensor output (SV) by the elapsed time (t 3). In S116, a characteristic correction value of the fluid to be measured for flow rate measurement is determined using a correction coefficient between the slope (SV/t3) of the change in sensor output and the thermal conductivity (W/m · K). In S117, gas correction based on the output from the characteristic value calculation unit 132 in which the correction value obtained from the slope of the change in the sensor output is reflected is performed, and the final volume flow rate (l/min) of the fluid is output.

As described above, in example 2, the physical property characteristic of the fluid is corrected based on the relationship between the slope of the change in sensor output and the thermal conductivity (W/m · K) at which the normalized detection value (SV) of the temperature detection unit 121 and the like reaches the second predetermined ratio, and the volume flow rate (L/min) is output. Thus, the difference in physical properties due to the approximation of the composition or type of the fluid to be measured can be determined using the slope of the change in sensor output. Even in the system using such transient response characteristics, flow measurement with higher accuracy can be performed without being affected by the physical properties of the fluid.

(example 3)

Next, as example 3, an example in which characteristic correction based on the sensor output fall time can be performed will be described. Fig. 13 is a process flow chart showing another example of the flow rate measurement process in the flow rate measurement device 1. First, in step S121, the measurement of the time is started when the heating unit 123 in the physical property value detection unit 12 is turned off, and in step S122, the elapsed time (t) is measured when the application of the current for driving the heating unit 123 is stopped (t 0). In S123, it is determined that the detected value (SV) of the temperature detector 121 or the like of the physical property value detector 12 is lower than the third predetermined ratio. The third predetermined ratio is a predetermined threshold value for determining the rise time, which is normalized by the heat balance value of the fluid to be measured. As the third predetermined ratio, for example, a value corresponding to approximately 95% is exemplified, assuming that the heat balance value of the fluid to be measured is 100%.

In the processing of S123, the output signal of the temperature detector 121 of the physical property value detector 12 or the like is transmitted to the characteristic value calculator 132 of the controller 13, and the sensor output SV is detected by the characteristic value calculator 132. Then, if the detected sensor output SV exceeds the third predetermined ratio (S123, yes), the process proceeds to S124, and if not (S123, no), the process proceeds to S122.

In step S124, the elapsed time is measured (t 4). In S125, the sensor output fall time is determined. More specifically, the sensor output fall time (t5) is determined based on the difference between the time (t4) at which the elapsed time measurement is made and the time (t0) at which the time measurement is started. In S126, a characteristic correction value of the fluid to be measured is determined using a correction coefficient between the sensor fall time and the thermal conductivity (W/m · K). In S127, gas correction based on the output from the characteristic value calculation unit 132 reflecting the correction value obtained from the sensor output fall time is performed, and the final volume flow rate (l/min) of the fluid is output.

As described above, in example 3, the physical performance characteristics of the fluid are corrected based on the relationship between the sensor output fall time and the thermal conductivity (W/m · K) in which the normalized detection value (SV) of the temperature detection unit 121 and the like is lower than the third predetermined ratio, and the volume flow rate (L/min) is output. Thus, the difference in physical properties due to the approximation of the composition or type of the fluid to be measured can be determined using the sensor output fall time as the transient response characteristic. Even in this manner, flow measurement with higher accuracy can be performed without being affected by the physical properties of the fluid.

(example 4)

Next, as example 4, an example in which the characteristic correction based on the sensor output (SV) with the passage of time can be performed will be described. Fig. 14 is a process flow chart showing another example of the flow rate measurement process in the flow rate measurement device 1. First, in step S131, the measurement of the elapsed time (t) is started at the timing when the heating unit 123 in the physical property value detection unit 12 is determined to be defective, and in step S132, the application of the current for driving the heating unit 123 is stopped (t 0). In S133, it is determined that the elapsed time during measurement has reached a predetermined time (t 6). In the processing of S133, when the elapsed time during measurement reaches a predetermined time (t6) (S133, yes), the routine proceeds to S134, and when the elapsed time does not reach the predetermined time (S133, no), the routine proceeds to S132.

In S134, the output signal of the temperature detector 121 of the physical property value detector 12 and the like is transmitted to the characteristic value calculator 132 of the controller 13, and the sensor output (SV) for a predetermined time (t6) is determined. In S135, a characteristic correction value of the fluid to be measured for flow rate measurement is determined using the determined correction coefficient between the sensor output (SV) and the thermal conductivity (W/m · K). In S136, gas correction based on the output from the characteristic value calculation unit 132 reflecting the correction value obtained from the sensor output (SV) is performed, and the final volume flow rate (l/min) of the fluid is output.

As described above, in example 4, the physical property characteristics of the fluid are corrected based on the relationship between the normalized detected value (SV) of the temperature detector 121 or the like after the elapse of the predetermined time and the thermal conductivity (W/m · K), and the volume flow rate (L/min) is output. Thus, the difference in physical properties due to the approximation of the composition or type of the fluid to be measured can be determined using the sensor output after the elapse of a predetermined time as the transient response characteristic. Even in this manner, flow measurement with higher accuracy can be performed without being affected by the physical properties of the fluid.

(example 5)

Next, a gas meter and a flow rate measurement device unit each equipped with the flow rate measurement device of embodiments 1 to 4 will be described as embodiment 5. The present embodiment is an example in which the flow rate measurement device 1 of embodiment 1 is incorporated in a gas meter for measuring the amount of gas used. Fig. 15 is a block diagram showing an example of a functional configuration of a gas meter 150 in which the flow rate measurement device 1 is incorporated. The gas meter 150 includes a display unit 151, a power supply unit 152, an operation unit 153, a vibration detection unit 154, a shutoff unit 155, a gas meter control unit 156 as an integrated control unit, a gas meter storage unit 157, and a gas meter communication unit 158, in addition to the flow rate measurement device 1. In addition, these components are housed in the case 150b except for the operation portion 153.

Here, the display unit 151 is a display for displaying the amount of gas used and the date and the presence or absence of a shut-off process (described later) based on the flow rate (the heat flow rate (J/min), the volume flow rate (l/min), or both) measured and output by the flow rate measuring device 1, and a liquid crystal display panel or the like may be used. The power supply unit 152 is a part that supplies power to other structures of the flow rate measuring device 1 and the gas meter 150, and may be configured by a storage battery such as an alkaline battery. The operation unit 153 is provided outside the gas meter 150 and operated by a gas contractor, an inspector, or the like. For example, operations such as resetting of the gas meter 150, adjustment of the timing, switching of the flow rate (the heat flow rate or the volume flow rate, or both) to be displayed and release of the shut-off state described later may be performed.

The vibration detection unit 154 includes, for example, an acceleration sensor (not shown) and detects the vibration of the gas meter 150 itself. The shutoff unit 155 has an actuator such as a solenoid and a valve for closing the main flow path unit 2, and when vibration equal to or greater than a threshold value is detected by the vibration detection unit 154, it is determined that an earthquake has occurred, and the gas passing through the main flow path unit 2 is shut off. The gas meter control unit 156 is electrically connected to the flow rate measuring device 1, the display unit 151, the power supply unit 152, the operation unit 153, the vibration detection unit 154, the shutoff unit 155, the gas meter storage unit 157, and the gas meter communication unit 158, and controls the respective units. For example, input information from the operation unit 153 is received, and a command corresponding to the input information is transmitted to each unit. When the vibration detection unit 154 detects an acceleration signal equal to or greater than the threshold value, a cutoff signal is transmitted to the cutoff unit 155. The gas meter storage unit 157 is a portion that stores the outputs from the flow rate measuring device 1 and the vibration detection unit 154 in time series over a predetermined period, and may be configured by a storage element such as an SRAM or a DRAM. The gas meter communication unit 158 can transmit various information processed by the gas meter control unit 156 to the outside in a wireless or wired manner, and can receive an external command or a set value and transmit the command or the set value to the gas meter control unit 156. Further, the communication unit 15 included in the flow rate measurement device 1 may communicate with the flow rate measurement device 1 to receive information processed by the control unit 13 of the flow rate measurement device 1, or may transmit a control signal or a set value to the flow rate measurement device 1.

In the configuration of the gas meter 150, for example, the flow rate measuring device 1, the display unit 151, the power supply unit 152, the vibration detection unit 154, the gas meter control unit 156, the gas meter storage unit 157, and the gas meter communication unit 158 may be unitized, and the gas meter 150 may be configured by electrically connecting the operation unit 153 and the shutoff unit 155 to the flow rate measuring device unit 150a and incorporating them into the housing 150 b. This enables the gas meter 150 to be manufactured more efficiently.

In the present embodiment, the configuration of the gas meter 150 and the flow rate measuring device unit 150a is an example, and can be changed according to the function of the gas meter 150 and the conditions in manufacturing. The flow rate measuring device of the present invention is not limited to the configuration shown in the above-described embodiment. The configurations of the above embodiments may be combined as much as possible without departing from the subject and technical idea of the present invention.

In the above-described embodiment, the description has been given of the modified example of the transient response of the detection values of the temperature detection units 121 and 122 using the physical property value detection unit 12 in the flow rate measurement device 1, but the same contents are also true for the detection values from the flow rate detection unit 11. That is, the flow rate measurement device 1 is configured by only the flow rate detection unit 11 without including the physical property value detection unit 12. In this case, the characteristic value calculation unit 132 of the control unit 13 may use the transient response of the detection values of the temperature detection units 111 and 112 of the flow rate detection unit 11 instead of the temperature detection units 121 and 122 of the physical property detection unit 12. For example, when the correction process is executed, the flow rate measurement value 1 is notified to a higher-level control unit such as a gas meter through the communication unit 15, and the flow path of the flow rate detection unit 11 is retained. The retention is performed by, for example, a valve that closes the main channel section 2 by the blocking section 155. In a state where the flow channel of the flow rate detection unit 11 is stagnant, the fluid flowing through the flow channel is in a calm state, and therefore the heat distribution by the heating unit 113 is in a state shown in fig. 5 (a). The flow rate measurement value 1 may be subjected to characteristic correction of transient response characteristics described with reference to fig. 11 to 14, based on the detection values of the temperature detection units 111 and 112 of the flow rate detection unit 11.

In the following, the constituent elements of the present invention are described with reference numerals in order to make it possible to compare the constituent elements with the configurations of the embodiments.

(invention 1)

A flow rate measurement device (1) that detects the flow rate of a fluid to be measured flowing through a main flow path (2), is characterized by comprising:

a heating unit (113) that heats a fluid to be measured;

temperature detection units (111, 112) that detect the temperature of the fluid to be measured;

and a flow rate correction unit (133) that corrects the flow rate of the fluid to be measured flowing through the main flow path based on a trend of change over time in the detection value of the temperature detection unit.

(invention 2)

The flow rate measurement device according to claim 1, wherein the flow rate correction unit (133) includes a correction unit (133), and the correction unit (133) corrects the flow rate of the measurement target fluid flowing in the main path based on a first elapsed period from a start of heating of the measurement target fluid to a point at which the detected value exceeds a first predetermined proportion of a thermal equilibrium temperature of the heated measurement target fluid in the vicinity of the temperature detection unit.

(invention 3)

The flow rate measurement device according to claim 1, wherein the flow rate correction unit (133) has a correction unit (133), and the correction unit (133) corrects the flow rate of the measurement target fluid flowing in the main path based on a slope of a change with time when the detection value reaches a second predetermined ratio in the vicinity of the temperature detection unit from the start of heating of the measurement target fluid.

(invention 4)

The flow rate measurement device according to claim 2 or 3, wherein the flow rate correction unit (133) has a correction means (133), and the correction means (133) corrects the flow rate of the measurement target fluid flowing in the main path based on a second elapsed period from when heating of the measurement target fluid is stopped until the detected value of the thermal equilibrium temperature becomes lower than a third predetermined proportion of the thermal equilibrium temperature.

(invention 5)

The flow rate measurement device according to claim 1, wherein the flow rate correction unit (133) has a correction unit (133), and the correction unit (133) corrects the flow rate of the measurement target fluid flowing through the main path based on the detection value at a time when a third elapsed period has elapsed since the start of heating of the measurement target fluid.

(invention 6)

The flow rate measurement device according to any one of claims 1 to 5, wherein the flow rate correction unit (133) acquires information indicating a change tendency of the detection value with time for correcting the flow rate of the measurement target fluid flowing in the main path when the flow of the measurement target fluid is in a stopped state.

(invention 7)

The flow rate measurement device according to any one of claims 1 to 6, characterized in that the heating portion and the temperature detection portion are arranged in a direction crossing a flow direction of the fluid to be measured.

(invention 8)

The flow rate measurement device according to claim 7, wherein a plurality of the temperature detection portions are provided, and at least two of the temperature detection portions are arranged at positions across the heating portion.

(invention 9)

The flow rate measurement device according to claim 7 or 8, wherein the temperature detection portion has a cold junction and a warm junction, the cold junction being located on an upstream side with respect to a flow direction of the measurement target fluid, and the warm junction being located on a downstream side with respect to the flow direction of the measurement target fluid.

(invention 10)

A flow rate measurement unit (150a) is provided with:

a flow measuring device (1) according to any of claims 1 to 9;

a display unit (151) that displays the flow rate corrected by the flow rate correction unit;

and an integrated control unit (156) that controls the flow rate measurement device and the display unit.

(invention 11)

A gas meter (150) is provided with:

a flow measuring device (1) according to any of claims 1 to 9;

a display unit (151) that displays the flow rate measured by the flow rate measurement device;

an integrated control unit (156) that controls the flow rate measurement device and the display unit;

a power supply unit (152) that supplies power to the flow rate measurement device (1), a display unit (151), and an integrated control unit (156);

a case (150b) that can house the flow rate measurement device (1), a display unit (151), and an integrated control unit (156);

and an operation unit (153) that enables setting relating to the operation of the flow rate measurement device from outside the housing (150 b).

Description of the symbols

1: flow rate measuring device

11: flow rate detecting unit

111: temperature detection unit

112: temperature detection unit

113: heating part

12: physical property value detecting part

121: temperature detection unit

122: temperature detection unit

123: heating part

13: control unit

131: detection value acquisition unit

132: characteristic value calculating section

133: flow rate calculating part

14: storage unit

141: correction table

15: communication unit

2: main flow path part

21: throttle hole

3: sub flow path part

32: flow path for detecting physical property value

33: flow path for flow rate detection

34: inflow channel

35: outflow channel

4: sealing element

5: circuit board

6: cover

100: sensor element

101: micro heater

102: thermopile

103: insulating film

104: silicon base station

105: hollow cavity

150: gas meter

150 a: flow rate measuring device unit