JP2012194122A - Vortex flowmeter and inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vortex flowmeter capable of determining a case that substances having hydrophobicity are adhered to a flow sensor, and an inspection method.SOLUTION: A vortex flowmeter includes: a thermal type flow sensor 10 having an ambient temperature sensor 17 for detecting the temperature of fluid and a heater 14 for heating the fluid; a drive circuit 5 for supplying electric energy to the heater 14 so as to make the temperature of the heater 14 higher than the temperature of the fluid detected by the ambient temperature sensor 17 by predetermined temperature; a predetermined physical quantity detecting section for detecting predetermined physical quantity corresponding to the electric energy; a threshold value setting section for setting a threshold value of the predetermined physical quantity on the basis of the flow rate of the fluid; and an adhesion determining section for determining whether substances having hydrophobicity are adhered to the thermal type flow sensor 10, on the basis of the predetermined physical quantity detected by the predetermined physical quantity detecting section and the threshold value set by the threshold value setting section.

Description

  Some embodiments according to the present invention relate to a vortex flowmeter and an inspection method.

  Conventionally, as this kind of vortex flowmeter, a vortex generator (Karman vortex) is generated by a vortex generator arranged in a flow path through which a fluid such as gas flows, and the flow rate of the fluid is measured (calculated) based on this frequency. Vortex flowmeters have been proposed and put into practical use. At present, a bypass channel perpendicular to the fluid flow direction is formed downstream of the vortex generator, and a flow sensor is arranged in the bypass channel, and the frequency of fluid vibration is detected by this flow sensor. Thus, a vortex flowmeter for calculating the volume flow rate of the fluid has been proposed and put into practical use. Furthermore, a vortex flowmeter that converts this volume flow rate into a mass flow rate is known (for example, see Patent Document 1).

JP 2004-93349 A

  By the way, when a hydrophobic substance, for example, a substance generally called oil, adheres to the flow sensor, the heat capacity of the flow sensor changes. As a result, since the vortex flowmeter described in the cited document 1 calculates the vortex frequency based on the detection signal of the flow sensor, sufficient signal sensitivity for vortex frequency detection cannot be obtained, and the flow rate is measured ( Output) could not be performed, or there were cases where a small flow rate was measured (output) compared to the actual flow rate of the fluid flowing through the flow path. In these cases, the flow rate of the measured (output) fluid alone cannot distinguish between the case where a hydrophobic substance is attached to the flow sensor and the case where the vortex flowmeter itself is faulty or abnormal in measurement. It was.

  Some aspects of the present invention have been made in view of the above-described problems, and an object thereof is to provide a vortex flowmeter and an inspection method capable of identifying a case where a hydrophobic substance adheres to a flow sensor. One of them.

  A vortex flowmeter according to the present invention is provided in a vortex generator for generating a vortex in a fluid flowing in a flow path, a bypass flow path in which an alternating flow is generated by the vortex, and a bypass flow path. A flow sensor for detecting an alternating flow, the flow sensor having an ambient temperature sensor for detecting the temperature of the fluid and a heater for heating the fluid; and a flow sensor in which the temperature of the heater is detected by the ambient temperature sensor. Based on the flow rate of the fluid, a supply unit that supplies electric energy to the heater so as to be higher than the temperature, a detection unit that detects the predetermined physical amount corresponding to the electric energy, Whether a substance having hydrophobicity is attached to the flow sensor based on the setting unit for setting the threshold value, the predetermined physical quantity detected by the detection unit, and the threshold value set by the setting unit Comprising a determining unit, the or.

  According to this configuration, the predetermined physical quantity corresponding to the electric energy supplied to the heater is detected, the predetermined physical quantity threshold is set based on the flow rate of the fluid, and the predetermined physical quantity detected by the detection unit Whether or not a hydrophobic substance is attached to the flow sensor is determined based on the threshold value set by the setting unit. Here, when the flow sensor is normal, the heat generated from the heater is taken away by the fluid by the alternating flow generated inside the bypass flow path. In this case, since the supply unit supplies electric energy to the heater so that the temperature of the heater is higher than the temperature of the fluid detected by the ambient temperature sensor, the electric energy supplied to the heater is It changes according to the amount of heat consumed by the heater (the amount of heat taken away by the fluid). Therefore, it has been confirmed through experiments and the like that the predetermined physical quantity corresponding to the electric energy supplied to the heater has a predetermined relationship (trend) with respect to the flow rate of the fluid.

  On the other hand, when a hydrophobic substance is attached to the flow sensor, the heat generated by the heater is lost to the attached substance, so that the heat capacity of the flow sensor increases. As a result, the electrical energy supplied to the heater is compared to the case where the flow sensor described above is normal with respect to the flow rate of the fluid, that is, compared to the case where a hydrophobic substance is not attached to the flow sensor. It has been confirmed by experiments that it becomes larger. Therefore, by setting a value larger than the predetermined physical quantity determined by the above-described predetermined relationship (trend) based on the flow rate of the fluid as a threshold value, the predetermined amount detected by the detection unit and the setting unit Based on the set threshold, it is possible to distinguish (distinguish) between cases where a hydrophobic substance is attached to the flow sensor and cases where a hydrophobic substance is not attached to the flow sensor. It becomes.

  Preferably, when the determination unit determines that a hydrophobic substance is attached to the flow sensor, the determination unit further includes a notification unit that notifies the fact.

  According to this configuration, when the determination unit determines that a hydrophobic substance is attached to the flow sensor, the fact is notified. Thereby, it is possible to easily notify a user (user) who is difficult to find out that a hydrophobic substance is attached to the flow sensor.

  Preferably, the apparatus further includes a calculation unit that calculates a flow rate of the fluid based on the frequency of the alternating flow detected by the flow sensor, and the setting unit is detected by the flow rate of the fluid calculated by the calculation unit and the detection unit. Based on the above-mentioned predetermined physical quantity, the threshold value of the above-mentioned predetermined physical quantity is set.

  According to this configuration, the threshold value of the predetermined physical quantity is set based on the fluid flow rate calculated by the calculation unit and the predetermined physical quantity detected by the detection unit. Thus, the set threshold value includes a frequency detection error (variation) by the mounted flow sensor and a predetermined physical quantity detection error (variation) by the mounted detection unit. As a result, a threshold value of a predetermined physical quantity based on the actually detected value is set, and a hydrophobic substance is adhered to the flow sensor and a hydrophobic substance is not adhered to the flow sensor. The case can be identified (discriminated) more accurately.

  Preferably, the apparatus further includes a pressure sensor that detects the pressure of the fluid, and the calculation unit uses the frequency of the alternating flow detected by the flow sensor, the temperature of the fluid detected by the ambient temperature sensor, and the pressure sensor as the flow rate of the fluid. Based on the detected pressure of the fluid, the mass flow rate of the fluid is calculated.

  According to this configuration, the flow rate of the fluid is determined based on the frequency of the alternating flow detected by the flow sensor, the temperature of the fluid detected by the ambient temperature sensor, and the pressure of the fluid detected by the pressure sensor. Mass flow rate is calculated. Thereby, it can use suitably, when the fluid which distribute | circulates a flow path is the gas of which volume changes with temperature and pressure, such as gas.

  Preferably, the setting unit sets the threshold value of the predetermined physical quantity until a predetermined time elapses after the flow sensor starts detecting the alternating flow.

  According to such a configuration, the predetermined threshold value of the predetermined physical quantity is set until a predetermined time elapses after the flow sensor starts detecting the alternating flow. Accordingly, it is possible to increase the probability that the threshold value is set before the hydrophobic substance adheres to the flow sensor. Thereby, a threshold value based on a normal flow sensor is set, and a case where a hydrophobic substance is attached to the flow sensor and a case where a hydrophobic substance is not attached to the flow sensor, It is possible to identify (discriminate) more accurately.

  Preferably, the predetermined physical quantity is one of current, power, and voltage.

  According to this configuration, the predetermined physical quantity is one of current, power, and voltage. Thereby, the predetermined physical quantity corresponding to the electrical energy supplied to the heater can be easily detected.

  Preferably, the aforementioned hydrophobic substance is oil.

  According to this configuration, the hydrophobic substance is oil. As a result, when oil remains in the pipe where the vortex flowmeter is installed, when other equipment installed in the pipe uses machine oil, when the fluid itself for measuring flow rate contains oil, For example, it can be suitably used.

  The inspection method according to the present invention is provided in a vortex generator for generating a vortex in a fluid flowing through the flow path, a bypass flow path in which an alternating flow is generated by the vortex, and the bypass flow path, A flow sensor for detecting an alternating flow, the flow sensor having an ambient temperature sensor for detecting a fluid temperature and a heater for heating the fluid, and a temperature of the fluid in which the heater temperature is detected by the ambient temperature sensor In a vortex flowmeter comprising a supply unit for supplying electric energy to a heater, a detection unit for detecting a predetermined physical quantity corresponding to the electric energy, a setting unit, and a determination unit so as to be higher than a predetermined temperature An inspection method for inspecting the state of the flow sensor, wherein the setting unit sets the threshold value of the predetermined physical quantity based on the flow rate of the fluid, and the determination unit detects by the detection unit. It has been based on a predetermined physical quantity that is set by the setting unit threshold, and a determination step of determining whether the substance having a hydrophobic flow sensor is attached.

  According to such a configuration, the threshold value of the predetermined physical quantity is set by the setting unit, and the flow is performed based on the predetermined physical quantity detected by the detection unit and the threshold value set by the setting unit by the determination unit. It is determined whether or not a hydrophobic substance is attached to the sensor. Here, when the flow sensor is normal, the heat generated from the heater is taken away by the fluid by the alternating flow generated inside the bypass flow path. In this case, since the supply unit supplies electric energy to the heater so that the temperature of the heater is higher than the temperature of the fluid detected by the ambient temperature sensor, the electric energy supplied to the heater is It changes according to the amount of heat consumed by the heater (the amount of heat taken away by the fluid). Therefore, it has been confirmed through experiments and the like that the predetermined physical quantity corresponding to the electric energy supplied to the heater has a predetermined relationship (trend) with respect to the flow rate of the fluid.

  On the other hand, when a hydrophobic substance is attached to the flow sensor, the heat generated by the heater is lost to the attached substance, so that the heat capacity of the flow sensor increases. As a result, the electrical energy supplied to the heater is compared to the case where the flow sensor described above is normal with respect to the flow rate of the fluid, that is, compared to the case where a hydrophobic substance is not attached to the flow sensor. It has been confirmed by experiments that it becomes larger. Therefore, by setting a value larger than the predetermined physical quantity determined by the above-described predetermined relationship (trend) based on the flow rate of the fluid as a threshold value, the predetermined amount detected by the detection unit and the setting unit Based on the set threshold, it is possible to distinguish (distinguish) between cases where a hydrophobic substance is attached to the flow sensor and cases where a hydrophobic substance is not attached to the flow sensor. It becomes.

  According to the vortex flowmeter and the inspection method according to the present invention, detection is performed by setting a value larger than the predetermined physical quantity determined by the above-described predetermined relationship (trend) as a threshold value based on the flow rate of the fluid. Based on the predetermined amount detected by the unit and the threshold value set by the setting unit, the hydrophobic substance is attached to the flow sensor and the hydrophobic substance is attached to the flow sensor. It is possible to identify (discriminate) the case where there is no. As a result, when a hydrophobic substance adheres to the flow sensor, the probability of erroneously measuring (outputting) a small flow rate can be reduced, and the reliability of the measured (output) flow rate can be increased. Can do.

It is a front view explaining the vortex flowmeter in 1st Embodiment of this invention. It is the II line arrow direction side view shown in FIG. It is a fragmentary sectional view of the vortex flowmeter shown in FIG. It is a fragmentary sectional view of the vortex flowmeter shown in FIG. It is sectional drawing explaining the internal structure of the vortex generator shown in FIG. FIG. 4 is a side view in the direction of arrows VI-VI shown in FIG. 3. It is a perspective view of the thermal type flow sensor shown in FIG. FIG. 8 is a cross-sectional view taken along line VIII-VIII shown in FIG. 7. It is a block diagram which shows the functional structure of the vortex flowmeter shown in FIG. FIG. 10 is a circuit diagram showing the drive circuit shown in FIG. 9. It is a block diagram which shows the functional structure of the central control part shown in FIG. It is a graph which shows an example of the relationship between the flow volume of a fluid, and the electric current supplied to a heater. It is a flowchart explaining the operation | movement which measures flow volume in the vortex flowmeter shown in FIG. It is a fragmentary sectional view of the vortex flowmeter in 2nd Embodiment of this invention. It is a block diagram which shows the functional structure of the vortex flowmeter shown in FIG. It is a block diagram which shows the functional structure of the central control part shown in FIG. It is a flowchart explaining the operation | movement which sets a threshold value in the vortex flowmeter shown in FIG. It is a flowchart explaining the operation | movement which measures flow volume in the vortex flowmeter shown in FIG.

  Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings. In the following description, the upper side of the drawing is referred to as “upper”, the lower side as “lower”, the left side as “left”, and the right side as “right”.

[First Embodiment]
1 to 13 are for illustrating a first embodiment of the present invention. FIG. 1 is a front view for explaining a vortex flowmeter according to the first embodiment of the present invention, and FIG. 2 is a side view in the direction of the arrow II shown in FIG. As shown in FIG. 1 and FIG. 2, the vortex flowmeter 1 is disposed in a fluid pipe 2 that forms a flow channel 2a through which a fluid to be measured (hereinafter simply referred to as a fluid) such as a gas flows, and in the flow channel 2a. The vortex generator 3 and the bypass channel 4 formed inside the vortex generator 3 are provided.

  The fluid pipe 2 is a short cylindrical member. As shown by broken lines in FIG. 1, pipes 100 through which fluid flows are connected to both ends of the fluid pipe 2.

  3 is a partial sectional view of the vortex flowmeter shown in FIG. 1, FIG. 4 is a partial sectional view of the vortex flowmeter shown in FIG. 2, and FIG. 5 is an internal structure of the vortex generator shown in FIG. FIG. 6 is a side view in the direction of arrows VI-VI shown in FIG. 3. As shown in FIGS. 2 to 6, the vortex generator 3 is a columnar member longer than the diameter of the fluid pipe 2, and the diameter of the vortex generator 3 enters the fluid pipe 2 from the through hole 2 b formed in the wall portion of the fluid pipe 2. It is inserted so as to cross in the direction. Between the outer periphery of the vortex generator 3 and the through hole 2 b of the fluid pipe 2, an O (O) ring 21 that maintains the hermeticity of the fluid pipe 2 is disposed. Further, the vortex generator 3 is fixed to the fluid pipe 2 by a fixing plate 22. The vortex generator 3 configured in this way generates vortices in the fluid flowing through the flow path 2a.

  The bypass channel 4 is formed to extend in a direction perpendicular to the fluid flow direction indicated by the arrow A in FIGS. 1 and 6 as indicated by the arrow B in FIG. Both ends of the bypass channel 4 are openings 4a. An alternating flow is generated inside the bypass channel 4 by a vortex street (Karman vortex) generated by the vortex generator 3.

  As shown in FIGS. 3 and 5, the vortex generator 3 has a fluid flow direction (in the direction of arrow A in FIG. 6) and a bypass from the middle of the bypass flow path 4 to above the vortex generator 3. A small-diameter hole 3a is formed so as to extend in a direction orthogonal to the extending direction of the flow path 4 (arrow B direction in FIG. 6). A pipe 23 having an outer diameter smaller than the inner diameter of the small diameter hole 3a is detachably inserted into the small diameter hole 3a. A sensor assembly 24 on which the thermal flow sensor 10 shown in FIG. 6 is mounted is fixed to the tip 23 a of the pipe 23. As shown in FIG. 3, the thermal flow sensor 10 is disposed at a position facing the bypass flow path 4 by inserting the tip 23 a of the pipe 23 to the deepest part of the small diameter hole 3 a.

  A large-diameter hole 3b having an inner diameter larger than that of the small-diameter hole 3a is formed above the small-diameter hole 3a. The pipe 23 inserted into the small diameter hole 3a of the vortex generator 3 is fixed by a fixing member 25 inserted into the large diameter hole 3b.

  A signal amplifying printed wiring board (not shown) of the thermal flow sensor 10 is provided on the outer peripheral surface of the fixing member 25, and the connection line 18 of the thermal flow sensor 10 passes through the internal space of the pipe 23. , Connected to this printed wiring board. The space surrounding the printed wiring board is protected by a cylindrical case 27 attached to the outside of the vortex generator 3 via an O (O) ring 26.

  As shown in FIGS. 1 to 4, a housing 28 is attached above the case 27. As shown in FIG. 4, a terminal 29 is built in the housing 28. The terminal 29 is provided with a printed wiring board 30 provided with a memory 7 and a central control unit 8 which will be described later. A cover 31 is screwed into the opening 28a of the housing 28, and a display unit 9 for displaying various information such as the measured fluid flow rate is provided on the opposite side of the opening 28a.

  7 is a perspective view of the thermal type flow sensor shown in FIG. 6, and FIG. 8 is a sectional view taken along the line VIII-VIII shown in FIG. The thermal flow sensor 10 is a flow sensor having a semiconductor diaphragm, which is disposed so as to be in contact with the fluid flowing in the bypass flow path 4 shown in FIGS. 2 to 6. As shown in FIGS. 7 and 8, the thermal flow sensor 10 is provided on the substrate 11 provided with the cavity 12, the insulating film 13 disposed on the substrate 11 so as to cover the cavity 12, and the insulating film 13. The heater 14 includes a first resistance temperature sensor 15 and a second resistance resistance element 16 disposed on both sides of the heater 14, an ambient temperature sensor 17, and the like.

  A portion of the insulating film 13 covering the cavity 12 forms a heat insulating diaphragm. The ambient temperature sensor 17 detects the temperature of the fluid flowing through the bypass channel 4 and outputs the detected temperature to the central control unit 8 described later. The heater 14 is a resistance element, for example, and is disposed at the center of the insulating film 13 covering the cavity 12, and heats the fluid flowing in the bypass flow path 4.

  The first resistance temperature detector 15 is used to detect the temperature of one side of the heater 14 (left side in FIGS. 7 and 8), and the second resistance temperature detector 16 is the other side of the heater 14 ( 7 and 8 are used to detect the temperature on the right side), and both function as a temperature sensor. The first and second resistance temperature detectors 15 and 16 detect sensor signals corresponding to a temperature difference caused by heating of the heater 14. This sensor signal is output to a central control unit 8 to be described later and subjected to signal processing such as signal amplification, rectangular wave conversion, and edge detection. Thereby, the central control unit 8 can obtain information on the frequency and amplitude in the alternating flow generated in the bypass flow path 4.

As a material of the substrate 11, silicon (Si) or the like can be used. As a material of the insulating film 13, silicon oxide (SiO ₂ ) or the like can be used. The cavity 12 is formed by anisotropic etching or the like. Platinum (Pt) or the like can be used for each material of the heater 14, the first resistance temperature detector 15, the second resistance temperature detector 16, and the ambient temperature sensor 17, and can be formed by a lithography method or the like. is there.

  FIG. 9 is a block diagram showing a functional configuration of the vortex flowmeter shown in FIG. 1, and FIG. 10 is a circuit diagram showing the drive circuit shown in FIG. As shown in FIG. 9, the vortex flowmeter 1 further includes a drive circuit 5. The drive circuit 5 is provided on the signal amplification printed wiring board (not shown) of the thermal flow sensor 10 described above. As shown in FIG. 10, the drive circuit 5 includes one operational amplifier OP1 and three fixed resistors R1, R2, and R3, and includes a heater 14 (denoted Rh in FIG. 10) and an ambient temperature sensor 17 (FIG. 10). The bridge circuit is configured using Rr. The drive circuit 5 controls the voltage applied to the operational amplifier OP1 based on the control signal of the central control unit 8 so that the resistance ratio between the heater 14 and the ambient temperature sensor 17 becomes a predetermined value (a constant value) ( Feedback control). In this way, the drive circuit 5 supplies electric energy to the heater 14 so that the temperature of the heater 14 is higher than the temperature of the fluid detected by the ambient temperature sensor 17 by a predetermined temperature.

  Note that the voltages Va and Vb across the fixed resistor R2 shown in FIG. 10 are output to an A / D converter (not shown) of the central controller 8 shown in FIG.

  The memory 7 is for storing information registered in advance before measuring the flow rate, information obtained during the measurement of the flow rate, and the like. Information stored in the memory 7 is written or read by the central control unit 8.

  FIG. 11 is a block diagram showing a functional configuration of the central control unit 8 shown in FIG. The central control unit 8 is constituted by, for example, a CPU and performs various calculations to control the operation of the vortex flow meter 1. As shown in FIG. 11, the central control unit 8 includes an alternating flow detection unit 81, a threshold setting unit 82, a flow rate calculation unit 83, a predetermined physical quantity detection unit 84, and an adhesion determination unit 85.

  The alternating flow detector 81 detects an alternating flow generated in the bypass flow path 4 and detects a frequency in the detected alternating flow. The alternating flow generated in the bypass flow path 4 is detected by sensor signals (voltage signals) by the temperature sensors (first temperature measuring resistance element and second temperature measuring resistance element) 15 and 16 of the thermal flow sensor 10. Detected as The alternating flow detector 81 calculates a frequency in the alternating flow based on sensor signals input from the temperature sensors (first and second resistance temperature detectors) 15 and 16. The alternating flow detector 81 calculates the amplitude in the alternating flow based on sensor signals input from the temperature sensors (first and second resistance temperature detectors) 15 and 16. You can also.

  The threshold setting unit 82 sets a threshold of a predetermined physical quantity corresponding to the electric energy supplied to the heater 14 based on the fluid flow rate.

  The flow rate calculation unit 83 calculates the flow rate of the fluid flowing through the flow path 2 a based on the frequency of the alternating flow detected by the thermal flow sensor 10 and calculated by the alternating flow detection unit 81.

  The predetermined physical quantity detection unit 84 detects a predetermined physical quantity corresponding to the electric energy supplied to the heater 14. In the present embodiment, the predetermined physical quantity detector 84 detects the current (heater current) Ih of the heater 14 as a predetermined physical quantity corresponding to the electrical energy supplied to the heater 14.

  The adhesion determination unit 85 has hydrophobicity in the thermal flow sensor 10 based on the predetermined physical quantity detected by the predetermined physical quantity detection unit 84 and the threshold value set by the threshold value setting unit 82. Determine whether the substance is attached.

  FIG. 12 is a graph showing an example of the relationship between the flow rate of the fluid and the current supplied to the heater 14. Here, when the thermal flow sensor 10 is normal, the heat generated from the heater 14 is taken away by the fluid by the alternating flow generated inside the bypass flow path 4. In this case, since the drive circuit 5 supplies electric energy to the heater 14 so that the temperature of the heater 14 is higher than the temperature of the fluid detected by the ambient temperature sensor 17, the electric energy is supplied to the heater 14. The electric energy to be changed varies according to the amount of heat consumed by the heater 14 (the amount of heat taken away by the fluid). Therefore, a predetermined physical quantity corresponding to the electrical energy supplied to the heater 14, for example, the current supplied to the heater 14, is related to the flow rate of the fluid as shown by a solid line in FIG. 12 (trend). It has been confirmed through experiments and the like.

  On the other hand, when a hydrophobic substance is attached to the thermal flow sensor 10, the heat generated from the heater 14 is lost to the attached substance, so that the heat capacity of the thermal flow sensor 10 increases. As a result, when the thermal flow sensor 10 described above is normal with respect to the flow rate of the fluid, the current supplied to the heater 14 is not attached to the thermal flow sensor 10, that is, a hydrophobic substance. It has been confirmed through experiments and the like that it becomes larger than the case.

In the present embodiment, the threshold value setting unit 82 sets a predetermined value, for example, a current value I ₀ of the heater 14 when the fluid flow rate is 0 (zero) [kg / s] in the graph L1 shown in FIG. A value obtained by adding 1 [mA] is preset as a threshold value T ₀ (T ₀ = I ₀ +1) and written (registered) in the memory 7. In this way, by setting a value larger than the current I ₀ supplied to the heater 14 shown in the graph L1 of FIG. 12 as the threshold value T ₀ based on the flow rate of the fluid, the predetermined physical quantity detection unit 84 Based on the detected heater current Ih and the threshold value T ₀ set by the threshold value setting unit 82, a case where a hydrophobic substance is attached to the thermal flow sensor 10 and the thermal flow sensor 10 are detected. It is possible to distinguish (discriminate) from a case where a hydrophobic substance is not attached.

  Moreover, although the electric current was shown as an example of the predetermined physical quantity corresponding to the electric energy supplied to the heater 14, it is not limited to this, For example, electric power or a voltage may be sufficient. As described above, the predetermined physical quantity corresponding to the electric energy supplied to the heater 14 is one of current, electric power, and voltage because the predetermined physical quantity corresponding to the electric energy supplied to the heater 14 is one of current, electric power, and voltage. Can be easily detected.

  In the present specification, the term “substance having hydrophobicity” is a concept including non-hydrophilic substances regardless of the degree of hydrophobicity. The index indicating the degree of hydrophobicity is not limited to the solubility in water, and may be another index.

  The hydrophobic substance that can adhere to the thermal flow sensor 10 is, for example, oil. When oil adheres to the thermal flow sensor 10, an oil film is formed at the adhering portion, and, for example, the sensitivity of the temperature sensors (first temperature measuring resistance element and second temperature measuring resistance element) 15 and 16 is lowered. In this way, when the hydrophobic substance mentioned above is oil, when oil remains in the pipe 100 where the vortex flowmeter 1 is installed, other equipment installed in the pipe 100 uses machine oil. In the case where oil is contained in the fluid itself for measuring the flow rate, it can be suitably used.

  In the present specification, the term “oil” means whether it is mineral (derived from minerals), animal (animal derived), or plant (derived from plants), or industrial. It means oil in a broad sense regardless of whether it is for fuel. Furthermore, it is a concept including what is generally called “fat” regardless of whether it is liquid or solid at normal temperature. The oil that can adhere to the thermal flow sensor 10 is preferably non-volatile oil.

  Next, an operation in which the vortex flowmeter 1 shown in FIG. 1 measures (calculates) the flow rate will be described.

  FIG. 13 is a flowchart for explaining the operation of measuring the flow rate in the vortex flowmeter 1 shown in FIG. As shown in FIG. 13, the vortex flowmeter 1 executes a flow rate measurement process S100 when measuring the flow rate of the fluid flowing through the flow path 2a. That is, first, the ambient temperature sensor 17 detects the temperature of the fluid flowing through the bypass flow path 4 (S101). The drive circuit 5 supplies electric energy to the heater 14 so that the temperature of the heater 14 becomes a predetermined temperature higher than the temperature detected by the ambient temperature sensor 17 (S102).

  On the other hand, the alternating flow generated in the bypass flow path 4 is detected by the temperature sensors (first temperature measuring resistance element and second temperature measuring resistance element) 15 and 16 of the thermal flow sensor 10, and the alternating flow is detected. The detection unit 81 calculates the frequency of the alternating flow based on the sensor signals input from the temperature sensors (first temperature measuring resistance element and second temperature measuring resistance element) 15 and 16 (S103). The flow rate calculation unit 83 uses a predetermined frequency such as a coefficient determined based on the width of the vortex generator 3, the number of straw hulls, and the cross-sectional area of the flow path to the frequency of the alternating flow calculated by the alternating flow detection unit 81 in S103. After calculating the volume flow rate of the fluid by multiplying by the coefficient, the mass flow rate is calculated from the temperature of the fluid measured by the temperature sensor and the pressure of the fluid measured by the built-in pressure gauge (S104).

  The flow rate calculation unit 83 calculates the mass flow rate of the fluid when the alternating flow amplitude calculated by the alternating flow detection unit 81 exceeds a predetermined value, and the alternating flow amplitude exceeds the predetermined value. If not, the mass flow rate of the fluid may be 0 (zero) [kg / s]. Thereby, the influence of the fluctuation of the fluid generated in the flow path 2a and the electric noise in the sensor signal can be reduced.

Next, the adhesion determination unit 85 accesses the memory 7 and determines whether or not a threshold is not set for the mass flow rate of the fluid calculated by the flow rate calculation unit 83 in S104 (S105). ). As described above, the threshold value setting unit 82 presets the threshold value T ₀ for the fluid flow rate of 0 (zero) [kg / s] and stores it in the memory 7. 85, when the mass flow rate of the fluid calculated by the flow rate calculation unit 83 is other than 0 (zero) [kg / s], it is determined that the threshold value is not set, and the fluid calculated by the flow rate calculation unit 83 When the mass flow rate is 0 (zero) [kg / s], it is determined that the threshold value is not yet set.

  As a result of the determination in S105, when the threshold value is not set, that is, when the threshold value is set, the predetermined physical quantity detection unit 84 uses the voltages Va and V of both ends of the fixed resistor R2 input from the drive circuit 5. The heater current Ih is calculated (detected) based on Vb (S106).

As a specific calculation method of the heater current Ih, for example, the predetermined physical quantity detection unit 84 uses the voltages Va and Vb at both ends of the fixed resistor R2 and the known resistance value r2 of the fixed resistor R2 as follows. The heater current Ih is calculated from the equation (1).
Ih = (Vb−Va) / r2 (1)

In addition, when using the electric power (heater electric power) Wh supplied to the heater as the predetermined physical quantity corresponding to the electric energy supplied to the heater 14, the predetermined physical quantity detection unit 84 uses the voltage Va at one end of the fixed resistor R2. The heater current Wh is calculated from the following formula (2) using the heater current Ih calculated by the formula (1).
Wh = Va × Ih (2)

After S106, attachment determination unit 85 reads a threshold value T ₀ stored in the memory 7, calculated by the predetermined physical quantity detecting unit 84 (detecting) has been heater current Ih is in S106, the threshold setting unit 82 It is determined whether or not the set threshold value T ₀ or less (S107).

If the heater current Ih is equal to or smaller than the threshold value T ₀ as a result of the determination in S107, or if the threshold value is not set as a result of the determination in S105, a substance having hydrophobicity is present in the thermal flow sensor 10. It is considered that no adhesion occurs or no threshold is set for the calculated mass flow rate of the fluid. Therefore, the adhesion determination unit 85 outputs the mass flow rate of the fluid calculated by the flow rate calculation unit 83 in S104 to the display unit 9 for display on the display unit 9 (S109), and ends the flow rate measurement process S100.

On the other hand, if the heater current Ih calculated (detected) by the predetermined physical quantity detector 84 exceeds the threshold T ₀ set by the threshold setting unit 82 as a result of the determination in S107, the thermal flow sensor 10 is hydrophobic. It is thought that the substance which has property has adhered. Therefore, the determination unit 84 displays (notifies) that the hydrophobic substance is attached to the thermal flow sensor 10 on the display unit 9 (S108), and ends the flow rate measurement process S100. Thereby, it is possible to easily notify a user (user) who is difficult to find out that a hydrophobic substance is attached to the thermal flow sensor 10 by himself / herself.

  In the present embodiment, an example is shown in which the display unit 9 displays (notifies) that a hydrophobic substance is attached to the thermal flow sensor 10, but the present invention is not limited to this. For example, the vortex flowmeter 1 includes a sound output unit such as a speaker and a light emitting unit such as an alarm lamp, and the determination unit 84 replaces the display unit 9 or together with the display unit 9 with the sound output unit and the light emitting unit. You may make it alert | report that the substance which has hydrophobicity has adhered to the thermal type flow sensor 10 by at least one of them.

  In the present embodiment, an example in which the threshold value setting unit 82 sets one threshold value for the flow rate of one fluid has been described, but the present invention is not limited to this. For example, the threshold setting unit 82 may set a plurality of thresholds for one fluid flow rate. In this case, in addition to determining whether or not a hydrophobic substance is attached to the thermal flow sensor 10, the adhesion determination unit 85 determines the degree (amount) of the hydrophobic substance attached to the thermal flow sensor 10. Can be determined step by step.

Thus, according to the vortex flowmeter 1 in the present embodiment, a predetermined physical quantity corresponding to the electrical energy supplied to the heater 14, for example, the heater current Ih is calculated (detected), and based on the fluid flow rate, A threshold value T ₀ of the heater current Ih is set, and based on the heater current Ih calculated (detected) by the predetermined physical quantity detection unit 84 and the threshold value T ₀ set by the threshold value setting unit 82, the thermal equation It is determined whether or not a hydrophobic substance is attached to the flow sensor 10. Here, when the thermal flow sensor 10 is normal, the heat generated from the heater 14 is taken away by the fluid by the alternating flow generated inside the bypass flow path 4. In this case, since the drive circuit 5 supplies electric energy to the heater 14 so that the temperature of the heater 14 is higher than the temperature of the fluid detected by the ambient temperature sensor 17, the electric energy is supplied to the heater 14. The electric energy to be changed varies according to the amount of heat consumed by the heater 14 (the amount of heat taken away by the fluid). Therefore, a predetermined physical quantity corresponding to the electrical energy supplied to the heater 14, for example, the current supplied to the heater 14, is related to the flow rate of the fluid as shown by a solid line in FIG. 12 (trend). It has been confirmed through experiments and the like.

On the other hand, when a hydrophobic substance is attached to the thermal flow sensor 10, the heat generated from the heater 14 is lost to the attached substance, so that the heat capacity of the thermal flow sensor 10 increases. As a result, when the thermal flow sensor 10 described above is normal with respect to the flow rate of the fluid, the current supplied to the heater 14 is not attached to the thermal flow sensor 10, that is, a hydrophobic substance. It has been confirmed through experiments and the like that it becomes larger than the case. Therefore, based on the flow rate of the fluid, the predetermined physical quantity detection unit 84 calculates the threshold value T ₀ by setting a value larger than the current I ₀ supplied to the heater 14 shown in the graph L1 of FIG. Based on the detected heater current Ih and the threshold value T ₀ set by the threshold value setting unit 82, a case where a hydrophobic substance is attached to the thermal flow sensor 10 and the thermal flow sensor 10 It is possible to distinguish (discriminate) the case where no hydrophobic substance is attached to the surface. As a result, when a hydrophobic substance is attached to the thermal flow sensor 10, the probability of erroneously measuring (outputting) a small flow rate can be reduced, and the reliability of the measured (output) flow rate can be reduced. Can be increased.

  Further, according to the vortex flowmeter 1 in the present embodiment, when the adhesion determination unit 85 determines that a hydrophobic substance is attached to the thermal flow sensor 10, the fact is displayed on the display unit 9. (Notification). Thereby, it is possible to easily notify a user (user) who is difficult to find out that a hydrophobic substance is attached to the thermal flow sensor 10 by himself / herself.

  Moreover, according to the vortex flowmeter 1 in the present embodiment, the predetermined physical quantity corresponding to the electric energy supplied to the heater 14 is any one of current, power, and voltage. Thereby, the predetermined physical quantity corresponding to the electrical energy supplied to the heater 14 can be easily detected.

  Moreover, according to the vortex flowmeter 1 in the present embodiment, the above-described hydrophobic substance is oil. As a result, when oil remains in the pipe 100 where the vortex flowmeter 1 is installed, or when other equipment installed in the pipe 100 uses machine oil, the fluid itself for measuring the flow rate contains oil. In such a case, it can be suitably used.

Further, according to the inspection method in the present embodiment, the threshold value setting unit 82 sets the threshold value T ₀ of the heater current Ih based on the fluid flow rate, and the adhesion determination unit 85 sets the predetermined physical quantity detection unit. Whether or not a hydrophobic substance is attached to the thermal type flow sensor 10 based on the heater current Ih calculated (detected) by 84 and the threshold value T ₀ set by the threshold value setting unit 82. Determined. Here, when the thermal flow sensor 10 is normal, the heat generated from the heater 14 is taken away by the fluid by the alternating flow generated inside the bypass flow path 4. In this case, since the drive circuit 5 supplies electric energy to the heater 14 so that the temperature of the heater 14 is higher than the temperature of the fluid detected by the ambient temperature sensor 17, the electric energy is supplied to the heater 14. The electric energy to be changed varies according to the amount of heat consumed by the heater 14 (the amount of heat taken away by the fluid). Therefore, a predetermined physical quantity corresponding to the electrical energy supplied to the heater 14, for example, the current supplied to the heater 14, is related to the flow rate of the fluid as shown by a solid line in FIG. 12 (trend). It has been confirmed through experiments and the like.

On the other hand, when a hydrophobic substance is attached to the thermal flow sensor 10, the heat generated from the heater 14 is lost to the attached substance, so that the heat capacity of the thermal flow sensor 10 increases. As a result, when the thermal flow sensor 10 described above is normal with respect to the flow rate of the fluid, the current supplied to the heater 14 is not attached to the thermal flow sensor 10, that is, a hydrophobic substance. It has been confirmed through experiments and the like that it becomes larger than the case. Therefore, based on the flow rate of the fluid, the predetermined physical quantity detection unit 84 calculates the threshold value T ₀ by setting a value larger than the current I ₀ supplied to the heater 14 shown in the graph L1 of FIG. Based on the detected heater current Ih and the threshold value T ₀ set by the threshold value setting unit 82, a case where a hydrophobic substance is attached to the thermal flow sensor 10 and the thermal flow sensor 10 It is possible to distinguish (discriminate) the case where no hydrophobic substance is attached to the surface. As a result, when a hydrophobic substance is attached to the thermal flow sensor 10, the probability of erroneously measuring (outputting) a small flow rate can be reduced, and the reliability of the measured (output) flow rate can be reduced. Can be increased.

[Second Embodiment]
14 to 18 are for illustrating a second embodiment of the present invention. Unless otherwise specified, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted. Further, components not shown in the figure are the same as those in the above-described embodiment.

  FIG. 14 is a partial cross-sectional view of the vortex flowmeter 1A according to the second embodiment of the present invention, and FIG. 15 is a block diagram showing a functional configuration of the vortex flowmeter 1A shown in FIG. As shown in FIG. 15, the vortex flowmeter 1 </ b> A of the present embodiment includes a pressure sensor 39 disposed inside a cylindrical case 27. The pressure sensor 39 is for detecting the pressure of the fluid, and as shown in FIG. 15, the pressure of the fluid detected by the pressure sensor 39 is input to the central control unit 8A.

  FIG. 16 is a block diagram showing a functional configuration of the central control unit 8A shown in FIG. As shown in FIG. 16, the central control unit 8A includes an alternating flow detection unit 81, a threshold setting unit 82A, a flow rate calculation unit 83A, a predetermined physical quantity detection unit 84, and an adhesion determination unit 85.

  In the present embodiment, the threshold value setting unit 82A is a predetermined flow rate corresponding to the fluid flow rate calculated by the flow rate calculation unit 83A and the electrical energy supplied to the heater 14 detected (calculated) by the predetermined physical quantity detection unit 84. Based on the physical quantity, a threshold value is set for the predetermined physical quantity. Thereby, the threshold value to be set includes a frequency detection error (variation) by the mounted thermal flow sensor 10 and a predetermined physical quantity detection error (variation) by the mounted predetermined physical quantity detection unit 84. included.

  In the present embodiment, the flow rate calculation unit 83A is detected by the thermal flow sensor 10 as the fluid flow rate, and is detected by the alternating flow frequency calculated by the alternating flow detection unit 81 and the ambient temperature sensor 17. The mass flow rate Q of the fluid is calculated based on the temperature of the fluid and the pressure of the fluid detected by the pressure sensor 39. Thereby, it can use suitably, when the fluid which distribute | circulates the flow path 2a is gas, such as gas, whose volume changes with temperature and pressure.

  Next, an operation in which the flow meter 1A shown in FIG. 14 sets a threshold value of a predetermined physical quantity will be described.

  FIG. 17 is a flowchart for explaining the operation of the flow meter 1A shown in FIG. 14 for setting a threshold value of a predetermined physical quantity. As shown in FIG. 17, the vortex flowmeter 1 </ b> A executes threshold setting processing S <b> 200 after being installed in the pipe 100 shown in FIG. 1. That is, first, the threshold setting unit 82A performs an initial process (S201).

In the initial processing S201, the threshold value setting unit 82A may set reads the previously stored data in the memory 7, for use in steps described below, the threshold set number m, a variety of values such as registered flow rate Q _n To do. Further, the threshold value setting unit 82A sets an initial value, for example, “1” to a subscript n indicating an index such as a registered flow rate Q _n used in a step described later.

In the example shown below, unless otherwise specified, the threshold setting number m is “3”, the registered flow rate Q ₁ is 90 [kg / s], and the registered flow rate Q ₂ is 100 [kg]. kg / s] is the registered flow rate Q ₃ is 100 [kg / s], is described as being set respectively.

  After the initial process S201, the pressure sensor 39 detects the pressure of the fluid (S202), and the vortex flowmeter 1A performs steps S101 to S103 in the same manner as the process S100 of the first embodiment shown in FIG. .

  After S103, the flow rate calculation unit 83A determines the frequency of the alternating flow detected by the alternating flow detection unit 81 in S103 based on the width of the vortex generator 3, the number of straw hulls, and the cross-sectional area of the flow path. The volume flow rate of the fluid is calculated by multiplying by a predetermined coefficient such as. Furthermore, the flow rate calculation unit 83A is based on the calculated volume flow rate of the fluid, the pressure of the fluid detected by the pressure sensor 39 in S201, and the temperature of the fluid detected by the ambient temperature sensor 17 in S101. The mass flow rate Q is calculated (S203).

  Next, the threshold value setting unit 82A determines whether or not the subscript n is the threshold value setting number m or less (n ≦ m) (S204).

The result of the determination in S204, if the subscript n is less than or equal to a threshold set number m, the threshold value setting unit 82A, the mass flow Q calculated by the flow rate calculation unit 83A in S203, the allowable range of the registration flow rate Q _n It is determined whether it is within (S205). As the allowable range, for example, a value such as ± 10 [kg / h] is set in the initial process S201. In this case, the allowable range of the registered flow rate Q ₁ is, for example, 80 [kg / s] or more and less than 95 [kg / s] (85 [kg / s] ≦ Q ₁ <95 [kg / s]). The allowable range of the registered flow rate Q ₂ is, for example, 95 [kg / s] or more and less than 105 [kg / s] (95 [kg / s] ≦ Q ₁ <105 [kg / s]). The allowable range of the flow rate Q ₃ is, for example, 105 [kg / s] or more and 115 [kg / s] or less (105 [kg / s] ≦ Q ₃ ≦ 115 [kg / s]). As a result, the registered flow rate Q _n covers a range of 85 [kg / s] or more and 115 [kg / s] or less (85 [kg / s] ≦ Q _n ≦ 115 [kg / s]). Can do.

  In the above-described example, ± 5 [kg / s] is set as the allowable range, but the present invention is not limited to this, and other values may be used. The allowable range may be determined simply by a predetermined value, or may be determined by a predetermined ratio with respect to the registered flow rate, for example, ± 5%. Moreover, the equal sign of the allowable range may be used for at least one of the upper limit and the lower limit, or may not be used for both the upper limit and the lower limit.

Note that the threshold setting number m, each registered flow rate Q _n , and the allowable range of each registered flow rate Q _n are preferably set as appropriate according to the specifications of the user (user) of the vortex flow meter 1A. In the above-described example, the flow rate measurement range required by the user (user) is 85 [kg / s] or more and 115 [kg / s] or less (85 [kg / s] ≦ Q _n ≦ 115 [kg]. / S]), it is an appropriate value.

Result of the determination in S205, if the mass flow rate Q is within an allowable range of the registration flow rate Q _n, the threshold value setting unit 82A accesses the memory 7, the predetermined physical quantity to the registration flow rate Q _n threshold T _n Is not set (S206). In this case, the threshold value setting unit 82A determines that the threshold value T _n corresponding to the registered flow rate Q _n is not set unless the threshold value T _n is stored (registered) in the memory 7, and corresponds to the registered flow rate Q _n . If the threshold value T _n is stored (registered) in the memory 7, it is determined that it is not set.

On the other hand, if the mass flow rate Q is not within the allowable range of the registered flow rate Q _n as a result of the determination in S205, the threshold value setting unit 82A increases the subscript n by, for example, “1” (increment: n = n + 1) ( (S207), the threshold value setting unit 82A performs the steps after S204 again.

Result of the determination in S206, if the threshold T _n predetermined physical quantity to the registration flow rate Q _n is not set, the predetermined physical quantity detecting unit 84, like the processing S100 of the first embodiment shown in FIG. 13, step S106 Do step.

After S106, the threshold value setting unit 82A are the heater current Ih calculated (detected) by a predetermined physical quantity detecting unit 84 in S106, by adding a predetermined value or a predetermined rate, the threshold value T _n memory 7 Is set and registered (S208). Next, the threshold value setting unit 82A sets an initial value, for example, “1” for the subscript n (S209), and the vortex flowmeter 1A performs each step from S201 again.

  On the other hand, as a result of the determination in S204, the subscript n is not less than or equal to the threshold setting number m, that is, the subscript n is larger than the threshold setting number m (n> m), and the determination result in S206 indicates the registered flow rate. If the threshold value Tn of the predetermined physical quantity for Qn is not yet set, that is, has been set, the threshold value setting unit 82A performs the above-described step of S209, and the vortex flowmeter 1A again performs the steps of S202 and subsequent steps. Do.

The threshold value setting process S200 ends when the vortex flowmeter 1A is installed in the pipe 100 shown in FIG. 1 and a predetermined time has elapsed after the detection of the alternating flow by the thermal flow sensor 10 has started. preferable. In this case, in the initial process S201, the threshold setting unit 82A starts measuring the set time based on, for example, a clock signal such as a crystal resonator built in the central control unit 8A. Further, after step S209, the threshold value setting unit 82A determines whether or not the set time is longer than the predetermined time (whether or not the predetermined time has elapsed from the start), and the set time is longer than the predetermined time. If larger, the threshold value setting process S200 ends. In this way, by setting the threshold value T _n of the current supplied to the heater 14 until a predetermined time elapses after the detection of the alternating flow by the thermal flow sensor 10 is started, the thermal flow It is possible to increase the probability that the threshold value T _n is set before the hydrophobic substance adheres to the sensor 10.

  Next, the operation in which the vortex flowmeter 1A shown in FIG. 14 measures (calculates) the flow rate will be described.

  FIG. 18 is a flowchart for explaining the operation of measuring the flow rate in the vortex flowmeter 1A shown in FIG. As shown in FIG. 18, the vortex flowmeter 1A executes the flow rate measurement process S300 when measuring the flow rate of the fluid flowing through the flow path 2a. That is, first, the flow rate calculation unit 83A performs an initial process (S301).

In the initial processing S301, similarly to the initial processing S201 described above, the flow rate calculation unit 83A reads the previously stored data in the memory 7, for use in steps described below, the threshold set number m, registered flow rate Q _n Set various values such as. Further, the threshold value setting unit 82A sets an initial value, for example, “1” for the subscript n used in a step described later.

  After the initial process S301, the vortex flowmeter 1A performs the above-described step S202, and further performs the steps S101 to S103 in the same manner as the process S100 of the first embodiment shown in FIG.

  After S103, the flow rate calculation unit 83A performs the above-described steps S203 to S205.

Result of the determination in S205, if the mass flow rate Q is within an allowable range of the registration flow rate Q _n, a predetermined physical quantity detecting unit 84, like the processing S100 of the first embodiment shown in FIG. 13, performs the steps of S106.

On the other hand, the result of the determination in S205, if the mass flow rate Q is not within the allowable range of the registration flow rate Q _n, the flow rate calculation unit 83A, an increase subscripts n, for example, by "1" (increment: n = n + 1) and (S207) The flow rate calculation unit 83A performs the steps after S204 again.

After S106, attachment determination unit 85 reads a threshold value T _n that is stored in the memory 7 based on the subscript n, is the heater current Ih calculated (detected) by a predetermined physical quantity detecting unit 84 in S106, the threshold It is determined whether or not the threshold value _{Tn is} less than or equal to the threshold value Tn set by the value setting unit 82 (S302).

Result of the determination in S302, if the heater current Ih is below the threshold value T _n, or the result of the determination in S204, the subscript n is not less than the threshold set number m, i.e., the number of the subscript n threshold setting When m is larger than n (n> m), the thermal flow sensor 10 is not attached with a hydrophobic substance, or a threshold is not set for the calculated mass flow rate Q of the fluid it is conceivable that. Therefore, the adhesion determination unit 85 outputs the mass flow rate Q of the fluid calculated by the flow rate calculation unit 83A in S203 to the display unit 9 for display on the display unit 9 (S303), and ends the flow rate measurement process S300.

On the other hand, the result of the determination in S302, the heater current Ih is not less than the threshold value T _n, i.e., greater than the threshold value T _n, similarly to the process S100 in the first embodiment shown in FIG. 13, attachment determination unit 85 Performs step S109 and ends the flow measurement process S300.

  In this embodiment, the example in which the threshold value is set by the threshold value setting process S200 has been described, but the present invention is not limited to this. For example, instead of the threshold value setting process S200 or together with the threshold value setting process S200, the threshold value setting unit 82A sets a threshold value for a predetermined flow rate in advance as in the first embodiment, It may be written (registered) in the memory 7.

As described above, according to the vortex flowmeter 1A in the present embodiment, the heater 14 is based on the fluid flow rate calculated by the flow rate calculation unit 83A and the heater current Ih calculated (detected) by the predetermined physical quantity detection unit 84. A threshold value T _{n of the} current supplied to is set. Accordingly, the threshold value T _n to be set includes a frequency detection error (variation) by the mounted thermal flow sensor 10 and a detection error of the current supplied to the heater 14 by the mounted predetermined physical quantity detection unit 84. (Variation). As a result, a threshold value T _n based on the actually detected value is set, and a case where a hydrophobic substance is attached to the thermal flow sensor 10 and a case where a hydrophobic substance is attached to the thermal flow sensor 10 It is possible to more accurately identify (determine) the case where it is not attached.

  Further, according to the vortex flowmeter 1A in the present embodiment, the flow rate of the fluid is detected by the thermal flow sensor 10 and is detected by the alternating flow frequency calculated by the alternating flow detector 81 and the ambient temperature sensor 17. The mass flow rate Q of the fluid is calculated on the basis of the temperature of the fluid and the pressure of the fluid detected by the pressure sensor 39. Thereby, it can use suitably, when the fluid which distribute | circulates the flow path 2a is gas, such as gas, whose volume changes with temperature and pressure.

Further, according to the vortex flowmeter 1A in the present embodiment, the threshold value T of the current supplied to the heater 14 after a predetermined time elapses after the detection of the alternating flow by the thermal flow sensor 10 is started. _n is set. Thereby, it is possible to increase the probability of setting the threshold value T _n before the hydrophobic substance adheres to the thermal flow sensor 10. Thereby, the threshold value T _n based on the thermal flow sensor 10 in a normal state is set, and when the hydrophobic substance is adhered to the thermal flow sensor 10 and the thermal flow sensor 10 is made hydrophobic. It is possible to more accurately discriminate (determine) the case where the substance has not adhered.

  Note that the configurations of the above-described embodiments may be combined or some of the components may be replaced. The configuration of the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1,1A ... Vortex flowmeter 2a ... Flow path 3 ... Vortex generator 4 ... Bypass flow path 5 ... Drive circuit 7 ... Memory 8, 8A ... Central control part 81 ... Alternating flow detection part 82, 82A ... Threshold setting part 83, 83A ... Flow rate calculation unit 84 ... Predetermined physical quantity detection unit 85 ... Adhesion determination unit 9 ... Display unit 10 ... Thermal flow sensor 14 ... Heater 17 ... Ambient temperature sensor 39 ... Pressure sensor

Claims (8)

A vortex generator that generates vortices in the fluid flowing through the flow path;
A bypass flow path in which an alternating flow is generated by the vortex;
A flow sensor provided in the bypass flow path for detecting the alternating flow, the flow sensor having an ambient temperature sensor for detecting the temperature of the fluid and a heater for heating the fluid;
A supply unit for supplying electric energy to the heater such that the temperature of the heater is higher than the temperature of the fluid detected by the ambient temperature sensor by a predetermined temperature;
A detection unit for detecting a predetermined physical quantity corresponding to the electrical energy;
A setting unit configured to set a threshold value of the predetermined physical quantity based on the flow rate of the fluid;
A determination unit for determining whether a substance having hydrophobicity is attached to the flow sensor based on a predetermined physical quantity detected by the detection unit and a threshold set by the setting unit; A vortex flowmeter characterized by comprising. 2. The vortex flowmeter according to claim 1, further comprising a notifying unit for notifying that when the determining unit determines that the hydrophobic substance is attached to the flow sensor. . Further comprising a calculation unit for calculating the flow rate of the fluid based on the frequency of the alternating flow detected by the flow sensor;
The setting unit sets a threshold value of the predetermined physical quantity based on the flow rate of the fluid calculated by the calculation unit and the predetermined physical quantity detected by the detection unit. Item 3. The vortex flowmeter according to item 1 or 2. A pressure sensor for detecting the pressure of the fluid;
The calculation unit, as the flow rate of the fluid, includes the frequency of the alternating flow detected by the flow sensor, the temperature of the fluid detected by the ambient temperature sensor, and the pressure of the fluid detected by the pressure sensor. The vortex flowmeter according to claim 3, wherein a mass flow rate of the fluid is calculated based on The said setting part sets the threshold value of the said predetermined | prescribed physical quantity until the predetermined time passes after the detection of the said alternating flow by the said flow sensor is started. The vortex flowmeter according to any one of the above. The vortex flowmeter according to any one of claims 1 to 5, wherein the predetermined physical quantity is one of current, power, and voltage. The vortex flowmeter according to claim 1, wherein the hydrophobic substance is oil. A vortex generator for generating a vortex in the fluid flowing through the flow path, a bypass flow path in which an alternating flow is generated by the vortex, and a bypass flow path provided in the bypass flow path for detecting the alternating flow A flow sensor having an ambient temperature sensor that detects a temperature of the fluid and a heater that heats the fluid; and a temperature of the heater that is higher than a temperature of the fluid detected by the ambient temperature sensor In a vortex flowmeter comprising a supply unit that supplies electrical energy to the heater, a detection unit that detects a predetermined physical quantity corresponding to the electrical energy, a setting unit, and a determination unit so as to increase a predetermined temperature An inspection method for inspecting the state of the flow sensor,
A setting step in which the setting unit sets a threshold value of the predetermined physical quantity based on the flow rate of the fluid;
The determination unit determines whether or not a hydrophobic substance is attached to the flow sensor based on a predetermined physical quantity detected by the detection unit and a threshold value set by the setting unit. An inspection method comprising: a determination step.

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