JP2012194123A - Vortex flowmeter and installation state inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vortex flowmeter capable of stabilizing flow rate of fluid to be measured (calculated).SOLUTION: A vortex flowmeter comprises a central control part 8 which calculates a flow velocity on the basis of a detection signal output from a thermal flow sensor 10, calculates the average of predetermined operation values, determines whether or not change in an alternating flow has occurred at a level within a predetermined range on the basis of the detection signal output from the thermal flow sensor, and selects at least one out of a plurality of the predetermined operation values for a predetermined period on the basis of the average stored in a memory 7. When it has been determined that the change in the alternating flow has occurred at the level within the predetermined range, the central control part 8 calculates the average for at least the one selected predetermined operation value.

Description

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

  Conventionally, as this kind of vortex flowmeter, a vortex train (Kalman vortex) is generated by a vortex generator arranged in a flow path through which a fluid such as gas flows to generate a fluid vibration, and based on the frequency of the fluid vibration. Vortex flowmeters that measure (calculate) the flow rate of fluid have been proposed and put into practical use. At present, a bypass flow path perpendicular to the fluid flow direction is formed on the downstream side of the vortex generator, and a thermal flow sensor is disposed in the bypass flow path. A vortex flowmeter that detects the frequency of the fluid and calculates 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

  In such a vortex flowmeter, when the velocity distribution from the center of the flow path to the wall surface is a uniform fluid, a uniform vortex train (Kalman vortex) is generated by the vortex generator, and the vortex flowmeter is generated inside the bypass flow path. An alternating flow is generated. The alternating flow is detected by a thermal flow sensor and a detection signal is output, and the vortex flowmeter measures (calculates) the flow rate of the fluid based on the detection signal.

  However, if the velocity distribution from the center of the channel to the wall surface is not a uniform flow, that is, if the fluid flow is turbulent (the fluid is a non-uniform flow), the alternating generated inside the bypass channel There was a case where the flow of water changed (fluctuated) suddenly (largely). In this case, since the vortex flowmeter measures (calculates) the flow rate of the fluid based on the detection signal that detects the alternating flow, a sudden change in the alternating flow is measured (calculated) as a unique flow rate. As a result, there is a problem that the flow rate of the measured (calculated) fluid is not stable (fluctuates greatly).

  Some aspects of the present invention have been made in view of the above-mentioned problems, and an object thereof is to provide a vortex flowmeter that can stabilize the flow rate of a fluid to be measured (calculated).

  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 that detects an alternating flow and outputs a detection signal based on the alternating flow; a calculation value calculation unit that calculates a predetermined calculation value based on the detection signal output from the flow sensor; An average value calculation unit that calculates an average value of predetermined calculation values, a storage unit that stores the average value calculated by the average value calculation unit, and a change in alternating flow based on a detection signal output from the flow sensor A plurality of predetermined calculation values calculated by the calculation value calculation unit in a predetermined period based on the above-described average value stored in the storage unit, and a determination unit that determines whether or not is a level within a predetermined range At least one of the And an average value calculation unit, when the determination unit determines that the change in the alternating flow is at the level of the predetermined range, the at least one selected by the selection unit An average value is calculated for a predetermined calculation value.

  According to such a configuration, based on the average value of the predetermined calculation values stored in the storage unit, among the plurality of the predetermined calculation values calculated by the calculation value calculation unit in the predetermined period, At least one is selected. As a result, the above-mentioned predetermined calculation of a specific value from the plurality of the above-mentioned predetermined calculation values in the above-mentioned predetermined period with reference to the average value of the above-mentioned predetermined calculation values calculated and stored in the past. It is possible to exclude values. In addition, when the determination unit determines that the change in the alternating flow is within the predetermined range, an average value is calculated for at least one predetermined calculation value selected by the selection unit. The As a result, when the flow of the fluid flowing through the flow path is disturbed (the fluid is a non-uniform flow), the average value is calculated with respect to the above-described predetermined calculation value excluding the specific value. Therefore, by calculating (measuring) the flow rate of the fluid based on this average value, the change can be made smaller (slowly and gently) than the actual flow rate.

  On the other hand, for example, when there is a step in the connection with the pipe, or when the length of at least one of the front and rear (upstream and downstream) of the vortex flowmeter is insufficient, etc. Is inadequate, the fluid flow becomes non-uniform (turbulent) and the alternating flow period changes. In this case, since the installation state on the pipe does not change with time, the alternating flow cycle continuously changes at a predetermined interval. Therefore, by counting the number of times the alternating flow cycle has changed in a predetermined period, the alternating flow cycle is continuously (transiently) changed from the alternating flow cycle. It is possible to identify (discriminate) the case where it has changed, and therefore, based on the number of times the alternating flow period detected by the flow sensor has changed in a given period, if there is an abnormality in the installation state of the pipe and the pipe It is possible to discriminate (determine) the case where there is no abnormality (normal) in the installation state.

  Preferably, the predetermined calculation value is one of an alternating flow frequency, a fluid velocity, and a fluid flow rate.

  According to this configuration, the predetermined calculation value is any one of an alternating flow frequency, a flow velocity (fluid velocity), and a fluid flow amount. Thereby, the above-mentioned predetermined calculation value can be easily calculated based on the sensor signal of the flow sensor, and the fluid flow rate can be easily calculated from the average value of the above-mentioned predetermined calculation value.

  Preferably, the apparatus further includes a conversion unit that converts the plurality of predetermined calculation values in the predetermined period into a digital signal sequence based on the average value stored in the storage unit, and the selection unit includes the digital signal sequence. Is subjected to predetermined pattern recognition processing, and at least one predetermined calculation value is selected from the plurality of predetermined calculation values in the predetermined period based on a result of the predetermined pattern recognition processing. select.

  According to this configuration, the plurality of predetermined calculation values in the predetermined range are converted into a digital signal sequence based on the average value stored in the storage unit, and pattern recognition processing is performed on the digital signal sequence. Is given. Here, when the flow rate (velocity) of the fluid is changing, the time-series change of the above-mentioned predetermined calculation value is based on the average value of the above-mentioned predetermined calculation values in the past. Can be classified into patterns. Similarly, when there is a sudden turbulence in the flow of fluid flowing through the flow path, similarly, the time-series change of the predetermined calculation value is based on the average value of the predetermined calculation values in the past. Then, it can be classified into some other specific pattern. On the other hand, by converting the time-series change of the predetermined calculation value described above into a digital signal sequence, it is easy to determine whether or not these specific patterns match (match). Therefore, by converting the plurality of predetermined calculation values in the predetermined period into a digital signal sequence based on the average value stored in the storage unit, and performing pattern recognition processing on the digital signal sequence It is possible to more accurately select the above-mentioned predetermined calculation value when the flow rate (velocity) of the fluid is changing, and more accurately exclude the above-mentioned predetermined calculation value of a unique value Is possible. As a result, the accuracy of the calculated (measured) fluid flow rate can be improved, and the possibility that the fluid flow rate may be dragged (affected) by the above-described predetermined calculation value having a unique value can be further reduced. The flow rate of the calculated (measured) fluid can be stabilized.

  Preferably, the apparatus further includes a moving average value calculation unit that calculates a moving average value for a predetermined number of the average values stored in the storage unit.

  According to such a configuration, the moving average value is calculated with respect to the predetermined number of average values stored in the storage unit. As a result, the moving average value is calculated with respect to the above-mentioned average value calculated and stored from a certain point in the past to the present, and the fluid flow rate is calculated (measured) based on the moving average value. This makes it possible to make the change even smaller (slowly and gently) than the actual flow rate. Thereby, the possibility that the flow rate of the fluid is dragged (affected) by the above-described predetermined calculation value having a unique value can be further reduced, and the calculated (measured) flow rate of the fluid can be further stabilized.

  Preferably, the predetermined number is greater than when the alternating flow change is less than the predetermined range level when the determination unit determines that the alternating flow change is at the predetermined range level. ,large.

  According to such a configuration, when the change in the alternating flow is determined to be the level within the predetermined range by the determination unit, the change in the alternating flow is less than the level within the predetermined range as described above. The predetermined number is large. As a result, when the flow of the fluid flowing through the flow path is turbulent (the fluid is a non-uniform flow), the flow of the fluid flowing through the flow path is not turbulent (the fluid is a uniform flow) Accordingly, since the number of moving average values (number of samples) increases, the moving average value of the predetermined calculation value is further smoothed. As a result, by calculating (measuring) the flow rate of the fluid based on this moving average value, it becomes possible to make the change even smaller (slowly and gently) than the actual flow rate, and the calculated (measured) fluid Can be further stabilized.

  Preferably, the moving average value calculated by the moving average value calculating unit is a weighted moving average value, and the moving average value calculating unit determines by the determining unit that the change in the alternating flow is at the level of the predetermined range. When the change is made, the weighting is changed when the change in the alternating flow is less than the predetermined range level.

  According to such a configuration, the moving average value calculated by the moving average value calculation unit is a weighted moving average value, and the moving average value calculation unit determines that the change in the alternating flow is at a level within the predetermined range by the determination unit. When it is determined that there is a change, the weighting changes when the change in the alternating flow is less than the predetermined range level. As a result, when the flow of the fluid flowing through the flow path is turbulent (the fluid is a non-uniform flow), the flow of the fluid flowing through the flow path is not turbulent (the fluid is a uniform flow) As a result, it is possible to further smooth the moving average value of the predetermined calculation value by reducing the weight of the latest (immediately preceding) average value. As a result, by calculating (measuring) the flow rate of the fluid based on this moving average value, it becomes possible to make the change even smaller (slowly and gently) than the actual flow rate, and the calculated (measured) fluid Can be further stabilized.

  Preferably, the storage unit further stores the moving average value calculated by the moving average value calculation unit, and the conversion unit performs the above-described predetermined period of time based on the above-described moving average value stored in the storage unit. A plurality of predetermined calculation values are converted into a digital signal sequence.

  According to such a configuration, the moving average value calculated by the moving average value calculation unit is further stored, and the plurality of predetermined calculations in the predetermined period based on the moving average value stored in the storage unit. The value is converted into a digital signal sequence. Here, when the flow rate (velocity) of the fluid is changing, the time-series change of the predetermined calculation value is based on the moving average value of the predetermined calculation value in the past. As in, it can be classified into several specific patterns. Similarly, when there is a sudden disturbance in the flow of fluid flowing through the flow path, similarly, the time-series change of the predetermined calculation value is based on the moving average value of the predetermined calculation value in the past. Then, as in the case of the above average value, it can be classified into some other specific patterns. On the other hand, by converting the time-series change of the predetermined calculation value described above into a digital signal sequence, it is easy to determine whether or not these specific patterns match (match). Therefore, the plurality of predetermined calculation values in the predetermined period are converted into a digital signal sequence based on the moving average value stored in the storage unit, and pattern recognition processing is performed on the digital signal sequence. This makes it possible to more accurately select the predetermined calculation value when the flow rate (velocity) of the fluid is changing, and more accurately exclude the predetermined calculation value of a unique value. It becomes possible. As a result, the accuracy of the calculated (measured) fluid flow rate can be improved, and the possibility that the fluid flow rate may be dragged (affected) by the above-described predetermined calculation value having a unique value can be further reduced. The flow rate of the calculated (measured) fluid can be stabilized.

  According to the vortex flowmeter according to the present invention, when the flow of the fluid flowing through the flow path is turbulent (the fluid is a non-uniform flow), the above-mentioned predetermined calculation value from which a unique value is excluded is obtained. On the other hand, since the average value is calculated, by calculating (measuring) the flow rate of the fluid based on the average value, the change can be made smaller (slowly and gently) than the actual flow rate. As a result, it is possible to reduce the possibility that the flow rate of the fluid is dragged (affected) by the above-described predetermined calculation value having a unique value, and to stabilize the calculated (measured) fluid flow rate. The risk of adversely affecting the control system that performs control based on the calculated (measured) fluid flow rate can be reduced, and the reliability of the calculated (measured) fluid flow rate can be increased.

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 explaining the example of the sensor signal in the thermal type flow sensor shown to FIG. 7 and FIG. It is a graph explaining the example of the sensor signal in the thermal type flow sensor shown to FIG. 7 and FIG. It is a graph explaining the example of the sensor signal in the thermal type flow sensor shown to FIG. 7 and FIG. It is a graph explaining the example of the sensor signal in the thermal type flow sensor shown to FIG. 7 and FIG. It is a graph explaining the example of the sensor signal in the thermal type flow sensor shown to FIG. 7 and FIG. It is a flowchart explaining the operation | movement which the vortex flowmeter shown in FIG. 1 measures the flow volume of the fluid. It is a graph for demonstrating the digital signal sequence which the digital conversion part shown in FIG. 11 converts. It is a front view explaining 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 the vortex flowmeter shown in FIG. 19 measures the flow volume of a fluid. It is a graph for demonstrating the digital signal sequence which the digital conversion part shown in FIG. 21 converts.

  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 18 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. Thereby, the vortex flowmeter 1 is installed in the pipe 100 through which the fluid flows in the direction indicated by the arrow A in FIG.

  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.

  As shown in FIG. 3, the signal amplification 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 is a pipe. The printed wiring board is connected through the internal space 23. The space surrounding the printed wiring board and the pressure sensor 39 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 resistance temperature detector 15 and the second resistance temperature detector 16 detect a sensor signal 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. As a result, the central control unit 8 can obtain information on the amplitude, frequency, and period of the alternating flow generated in the bypass flow path 4. The sensor signal of this embodiment corresponds to an example of “detection signal” in the present invention.

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, a memory 7, a central control unit 8, an analog output unit 50, and a digital communication unit 60.

  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. In the drive circuit 5, the voltage applied to the operational amplifier OP1 is controlled (feedback control) so that the resistance ratio between the heater 14 and the ambient temperature sensor 17 becomes a predetermined value (a constant value). In this way, the drive circuit 5 supplies electric power (current) 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.

  The memory 7 is, for example, a non-volatile storage means for storing information registered in advance before the flow rate measurement, information obtained during the flow rate measurement, and the like. Information stored in the memory 7 is written or read by the central control unit 8.

  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.

  The analog output unit 50 is for converting a control signal and data input from the central control unit 8 into a voltage signal or a current signal and outputting the voltage signal or current signal to the outside of the vortex flowmeter 1. The analog output unit 50 includes an output terminal, and outputs an analog signal to an external device such as a controller connected to the output terminal.

  The digital communication unit 60 is for transmitting control signals and data input from the central control unit 8 to the outside of the vortex flow meter 1 and receiving control signals and data from the outside of the vortex flow meter 1. The digital communication unit 160 includes an output terminal and communicates a digital signal with an external device connected to the output terminal, for example, a central monitoring device. The digital communication unit 60 may be an output terminal including a contact (pin) that simply outputs ON / OFF.

  FIG. 11 is a block diagram showing a functional configuration of the central control unit 8 shown in FIG. As shown in FIG. 11, the central control unit 8 includes an alternating frequency calculation unit 81, a flow velocity calculation unit 82, an output control unit 83, an alternating flow determination unit 84, a digital signal conversion unit 85, and a calculation value selection unit. 86, an average value calculation unit 87, a notification control unit 88, and a flow rate calculation unit 89.

  The alternating frequency calculation unit 81 calculates (detects) a frequency (alternating frequency) in the alternating flow based on the sensor signal input from the thermal flow sensor 10.

  The flow velocity calculation unit 82 calculates a flow velocity (fluid velocity) FV based on the alternating frequency calculated (detected) by the alternating frequency calculation unit 81. The flow velocity calculation unit 82 of the present embodiment corresponds to an example of the “calculation value calculation unit” in the present invention, and the flow velocity (fluid velocity) FV of the present embodiment is the “predetermined calculation value” in the present invention. It corresponds to an example.

  In the present embodiment, an example in which the predetermined calculation value is the flow velocity (fluid velocity) FV is shown, but the present invention is not limited to this. The predetermined calculation value may be an alternating frequency (an alternating flow frequency) or a fluid flow rate. As described above, the predetermined calculation value is one of the frequency of the alternating flow, the flow velocity (fluid velocity) FV, and the flow rate of the fluid. While being able to calculate easily based on a sensor signal, the flow volume of the fluid can be easily calculated from the average value of predetermined calculation values.

  The output control unit 83 outputs the fluid flow rate calculated by the later-described flow rate calculation unit 89 to the display unit 9 and displays it on the display unit 9 for each update cycle UT (S115).

  The alternating flow determination unit 84 determines whether or not the alternating flow has changed based on the sensor signal input from the thermal flow sensor 10. Further, the alternating flow determination unit 84 determines whether or not the change in the alternating flow is within a predetermined range.

  The digital signal converter 85 converts the plurality of flow velocities FV into digital signal sequences based on the average value AV of the flow velocities FV calculated by the average value calculator 87 described later and stored in the memory 7.

  The calculated value selection unit 86 selects at least one of the plurality of flow rates FV calculated by the flow rate calculation unit 82 in the update period UT based on the average value AV of the flow rates FV stored in the memory 7. This makes it possible to exclude a flow rate FV having a specific value from a plurality of flow rates FV in the update period UT with reference to the average value AV of the flow rates FV calculated and stored in the past.

  The average value calculation unit 87 calculates the average value AV of the flow velocity FV and writes the calculated average value AV in the memory 7.

  When the flow of the fluid flowing through the flow path 2a is disturbed (the fluid is a non-uniform flow), the notification control unit 88 displays (notifies) that effect on the display unit 9.

  The flow rate calculation unit 89 calculates the fluid flow rate Q based on the average value AV of the flow velocity FV calculated by the average value calculation unit 87.

  12 to 16 are graphs for explaining examples of sensor signals in the thermal flow sensor 10 shown in FIGS. 7 and 8. 11 to 15, the horizontal axis represents time t and the vertical axis represents voltage V. The alternating flow generated in the bypass flow path 4 changes in voltage over time by the temperature sensors (first and second resistance temperature measuring elements) 15 and 16 of the thermal flow sensor 10. Is detected as a sensor signal. When the fluid flowing through the flow path 2a has a uniform or substantially uniform flow from the center to the wall surface of the flow path 2a (hereinafter simply referred to as a uniform flow), the alternating generated in the bypass flow path 4 Is detected as a sensor signal having a waveform as shown in FIG. 12, for example, and ideally becomes a periodic signal such as a sine wave. This sensor signal is vertically symmetrical with respect to the center value c of the amplitude a (a value obtained by subtracting the lower limit value from the upper limit value), and has a positive half-wave (upward convex wave) period and a negative half-wave period. And are equal. When the speed (flow velocity) of the fluid flowing through the flow path 2a, that is, the flow rate of the fluid changes from a predetermined value (a constant value), the sensor signal has an amplitude a1 and a period corresponding to the changed flow rate of the fluid after a predetermined time has elapsed. It changes to the signal of T1.

  On the other hand, when the fluid flowing through the flow path 2a is not a uniform flow, that is, when the flow is turbulent (the fluid is a non-uniform flow), the sensor signal of the thermal flow sensor 10 is, for example, as shown in FIG. As shown, the period T2 / 2 of the positive half-wave (wave convex upward) and the period T2 ′ / 2 of the negative half-wave are asymmetric (T2 / 2 ≠ T2 ′ / 2), and are short. Suddenly in time, it can be a signal whose period changes abruptly (largely). Further, for example, as shown in FIG. 14, the sensor signal of the thermal flow sensor 10 is the second positive half wave with respect to the period T3 / 2 of the first positive half wave (wave convex upward). Period T3 ′ / 2 becomes a double waveform (T3 = T3 ′ / 2), and in a short time, the period suddenly changes rapidly (largely), and a signal with a missing half period may occur. . For example, as shown in FIG. 15, the sensor signal of the thermal flow sensor 10 is short from the amplitude a4 of the first periodic signal to the amplitude a4 ′ of the third periodic signal (a4> a4 ′). Suddenly in time, the signal can change abruptly (largely) in amplitude. Further, for example, as shown in FIG. 16, the sensor signal of the thermal flow sensor 10 is changed from the center value c5 of the first periodic signal to the center value c5 ′ of the third periodic signal (c5 ≠ c5 ′). The signal may change suddenly (largely) in the center value suddenly in a short time.

  The waveform of the sensor signal as shown in FIGS. 13 to 16 may appear temporarily when the flow rate (velocity) of the fluid flowing through the flow path 2a changes. Further, when the vortex flowmeter 1 is installed in an inappropriate state on the pipe 100 shown in FIG. 1, for example, when there is a step in the connection portion between the fluid pipe 2 and the pipe 100 shown in FIG. When the pipe 100 connected to the fluid pipe 2 of the flow meter 1 does not satisfy a predetermined installation requirement (installation condition), for example, the length of at least one straight line before and after (upstream and downstream) of the vortex flow meter 1 is It may also appear when there is a shortage.

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

  FIG. 17 is a flowchart for explaining the operation in which the vortex flowmeter 1 shown in FIG. 1 measures (calculates) the fluid flow rate. 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 central control unit 8 performs initial processing (S101).

  In the initial process S101, the central control unit 8 reads data stored in advance in the memory 7, and sets various values such as an update cycle UT and a predetermined range (width) Δ used in steps to be described later. In addition, the central control unit 8 uses a subscript m incremented for each detection cycle dt (m is a positive integer) and a subscript n incremented for each update cycle UT (n is a positive integer) used in steps described later. For example, set the initial value. Furthermore, the central control unit 8 starts measuring time based on, for example, a clock signal such as a built-in crystal resonator.

  Next, the ambient temperature sensor 17 detects the temperature of the fluid flowing in the bypass flow path 4 (S102). The drive circuit 5 supplies electric power (current) 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 (S103).

  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, and the alternating frequency calculating unit 81 Based on the sensor signals input from the sensors (first temperature measuring resistance element and second temperature measuring resistance element) 15 and 16, an alternating flow frequency (alternating frequency) is calculated (detected) (S104).

The flow velocity calculation unit 82 uses the alternating frequency calculated (detected) by the alternating frequency calculation unit 81 in S103 and a predetermined coefficient such as a coefficient determined based on the width of the vortex generator 3 and the Strouhal number. The fluid velocity (flow velocity) FV is calculated (S105), and the calculated fluid velocity FV is written in the memory 7. The memory 7 additionally stores the flow velocity FV every time step S105 is performed, and the central control unit 8 uses the subscript m to store any flow velocity FV _m (FV ₁ , FV ₂ ,..., FV written in the past). _m−1 , FV _m ) can be read from the memory 7.

  Next, the output control unit 83 determines whether or not the elapsed time since the start of measurement is less than the update cycle UT (S106).

  As a result of the determination in S106, when the elapsed time is less than the update cycle UT, the vortex flowmeter 1 performs the steps subsequent to S102 again. Each step from S102 to S104 is performed in the detection cycle dt, and the detection cycle dt is shorter than the update cycle UT (dt <UT). Thereby, the flow velocity FV is calculated and stored a plurality of times during the update cycle UT.

  On the other hand, if the elapsed time is not less than the update cycle UT as a result of the determination in S106, that is, if the elapsed time is equal to or longer than the update cycle UT, the alternating flow determination unit 84 determines whether the temperature sensor (first temperature resistance element Based on the sensor signals input from the second and second resistance temperature detectors 15 and 16, it is determined whether or not the alternating flow has changed (S107).

Specifically, for example, before the determination in S106, the central control unit 8 determines whether the temperature sensors (first temperature measuring resistance element and second temperature measuring resistance element) 15, 16 are detected during the detection time t. Based on the inputted sensor signal, the cycle of the alternating flow is detected and written in the memory 7. Then, prior to the determination of S107 after the determination of S106, the central control unit 8, based on the period of a plurality of alternating flow detected in update cycle UT, the period of the alternating flow in the current update period UT _n (Or its average value) is calculated. Then, in S107, the alternating flow determination unit 84 determines the alternating flow cycle (or the average value) in the previous update cycle UT _{n-1 and} the alternating flow cycle (or the average value) in the current update cycle UT _n (or When the difference is equal to or greater than a predetermined value, it is determined that the alternating flow has changed. On the other hand, the alternating flow cycle (or the average value) in the previous update cycle UT _n-1 is compared with the alternating flow cycle (or the average value) in the current update cycle UT _n . If there is not, or if the difference is less than the predetermined value, the alternating flow determination unit 84 determines that the alternating flow has not changed.

  Note that the target of the determination criterion in the determination in S107 is not limited to the alternating flow cycle, and may be, for example, the ratio at which the missing period of the sensor signal shown in FIG. 14 occurs in the update cycle UT. The variation width of the amplitude of the sensor signal shown in FIG.

If the alternating flow has changed as a result of the determination in S107, the alternating flow determination unit 84 uses the sensor signals input from the temperature sensors (first and second resistance temperature detectors) 15 and 16 as the sensor signals. Based on this, it is determined whether or not the change in the alternating flow is within a predetermined range (S108). In the case of the above-described example, the alternating flow determination unit 84 performs the alternating flow cycle (or an average value thereof) in the previous update cycle UT _{n-1 and} the alternating flow cycle (or the average value thereof) in the current update cycle UT _n . When the difference from the average value is within a predetermined range, it is determined that the change is within the predetermined range, and when the difference is outside the predetermined range (exceeds the predetermined range), it is determined that the change is not within the predetermined range. .

As a result of the determination in S108, when the change in the alternating flow is within a predetermined range, the flow of the fluid flowing through the flow path 2a is disturbed (non-uniform flow), but based on the alternating flow Even if the flow rate of the fluid is calculated, it is considered that the allowable range of the required measurement accuracy can be maintained (maintained). Therefore, the digital signal conversion unit 85 reads the flow velocity FV and an average value AV, which will be described later, from the memory 7, and converts a plurality of flow velocity FV included in the current update cycle UT _n into a digital signal sequence based on the average value AV. (S109).

FIG. 18 is a graph for explaining a digital signal sequence converted by the digital conversion unit 85 shown in FIG. As shown in FIG. 18, the flow velocity FV is calculated in the detection cycle dt, and a plurality of, for example, 18 flow velocity FVs in FIG. 18 are included in the update cycle UT. In S111 step or S113 step to be described later, the average value AV _n-1 flow rate FV is calculated in the previous update cycle UT _n-1, is stored in the memory 7. The average value AV is set with a predetermined range (width) Δ, for example, ± 5 [%] in the initial process S101. Therefore, for example, when the average value AV _n-1 is 100 [m / s], the predetermined range (width) Δ of the average value AV _n-1 is 95 [m / s] or more and 105 [m / s]. Less than. In this state, the digital signal conversion unit 85 compares the predetermined range (width) Δ of the previous average value AV _n−1 with each flow velocity FV included in the current update period UT _n , and the flow velocity FV is the previous average. a value AV _n-1 of a predetermined range (width) is within delta to "0", the if the predetermined range (width) delta outside of the flow velocity FV is the previous average value AV _n-1 "1", respectively converted To do. For example, in the case of the example shown in FIG. 18, the fifth, sixth, and twelfth flow velocities FV that are shaded in FIG. 18 are within a predetermined range (width) Δ of the previous average value AV _n−1. Is out of range. In this case, the plurality of flow velocities FV included in the current update cycle UT _n are converted into a digital signal string “000011000001000000”.

  After step S109, the calculation value selection unit 86 performs pattern recognition processing on the digital signal sequence converted in step S109 (S110). In the pattern recognition processing S110, the calculation value selection unit 86 determines whether the digital signal sequence corresponds to a predetermined pattern, and selects at least one flow velocity FV from the digital signal sequence based on the determination result.

  Here, when the flow rate (velocity) of the fluid is changing, the time-series change of the flow velocity FV can be classified into some specific patterns based on the average value AV of the past flow velocity FV. . Similarly, when there is a sudden turbulence in the flow of the fluid flowing through the flow path 2a, the time-series change of the flow velocity FV is also different from the average value AV of the past flow velocity FV. Can be classified into specific patterns. On the other hand, by converting the time-series change of the flow velocity FV into a digital signal sequence, it is easy to determine whether or not these specific patterns are matched (matched). Therefore, by converting a plurality of flow velocities FV in the update period UT into a digital signal sequence based on the average value AV stored in the memory 7, and performing pattern recognition processing S110 on the digital signal sequence, the flow rate of fluid ( It becomes possible to select the flow velocity FV when the (velocity) is changing more accurately and to exclude the flow velocity FV having a specific value more accurately.

Specifically, for example, in the digital signal sequence, when “1” continues for a predetermined number, for example, three or more like “........ 11”, the actual flow velocity is an average value in the current update cycle UT _n . It is considered that the value has changed beyond a predetermined range (width) Δ of AV. Even if “1” is not continuous, if “1” continues for a predetermined number, for example, three or more, with “01” in between, for example “... In UT _n , it is considered that the actual flow velocity changes in the vicinity of a predetermined range (width) Δ of the average value AV. Furthermore, even when “1” is included in the digital signal sequence at a predetermined ratio, for example, 50 [%] or more, it is considered that the actual flow velocity changes beyond the predetermined range (width) Δ of the average value AV. . Therefore, when the digital signal sequence has these patterns, the flow rate FV exceeds the predetermined range (width) Δ of the average value AV because the actual fluid flow rate (velocity) has changed. The selection unit 86 selects all the flow velocities FV corresponding to the digital signal sequence.

On the other hand, for example, in a digital signal sequence, “1” is not continuous by a predetermined number, for example, 3 or more, such as “... 01000110. Is included in a predetermined ratio, for example, 20 [%] or less, in the current update cycle UT _n , there is a sudden disturbance in the flow of the fluid flowing through the flow path 2a (the fluid is suddenly uneven). It is thought that the Therefore, when the digital signal sequence has these patterns, the calculation value selection unit 86 selects the flow velocity FV corresponding to “0” and excludes the flow velocity FV corresponding to “1” in the digital signal sequence. In the case of the example shown in FIG. 18, the digital signal sequence is “000011000001000000”, and there is a sudden disturbance in the flow of the fluid flowing through the flow path 2a (the fluid suddenly becomes an uneven flow). Since it is considered, the calculation value selection part 86 excludes the 5th, 6th, and 12th flow velocity FV, and selects the other flow velocity FV.

After the step of S110, the average value calculation unit 87 calculates an average value for the selected flow velocity FV (S111), and writes the calculated average value AV in the memory 7. The memory 7 additionally stores the average value AV in time series every time the step S111 or the later-described step S113 is performed, and the central control unit 8 uses the subscript n to write any average value written in the past. AV _n (AV ₁ , AV ₂ ,..., AV _n−1 , AV _n ) can be read from the memory 7. As described above, when the alternating flow determination unit 84 determines that the change in the alternating flow is within a predetermined range, the average value AV is obtained for at least one flow velocity FV selected by the calculation value selection unit 86. Is calculated. As a result, when the flow of the fluid flowing through the flow path 2a is disturbed (the fluid is a non-uniform flow), the average value AV is calculated for the flow velocity FV from which the unique value is excluded. By calculating (measuring) the flow rate of the fluid based on the average value AV, it becomes possible to make the change smaller (slowly and gently) than the actual flow rate.

  On the other hand, as a result of the determination in S108, if the change in the alternating flow is not at a predetermined range level, that is, if the change exceeds the predetermined range level, continuously to the flow of the fluid flowing through the flow path 2a, or It is considered that there is a large disturbance and the flow rate of the fluid cannot be calculated based on the alternating flow, or even if it is calculated, the required measurement accuracy tolerance cannot be satisfied. In this case, as described above, when the vortex flowmeter 1 is installed in an inappropriate state on the pipe 100 shown in FIG. 1, or when the pipe 100 connected to the fluid pipe 2 of the vortex flowmeter 1 is predetermined. It is assumed that the installation requirements (installation conditions) are not satisfied. Therefore, the notification control unit 88 causes the display unit 9 to display (notify) that the fluid flow is disturbed (S112). Thereby, it is possible to easily notify a user (user) who is difficult to find the turbulence of the fluid himself.

  In S <b> 112, the central control unit 8 preferably further writes and stores information related to the fluid flow disturbance, such as the date and time of occurrence, in the memory 7. This makes it possible to leave a history when the fluid flow is disturbed.

  In the present embodiment, the example in which the display unit 9 displays (notifies) that the fluid flow is disturbed in the notification control unit 88 in S112 is not limited to this. For example, the vortex flowmeter 1 includes an audio output means such as a speaker or a light emitting means such as an alarm lamp instead of the display unit 9 or together with the display unit 9, and at least one of the audio output unit and the light emitting unit. In addition, the fact that there is an abnormality in the installation state in the pipe 100 may be notified, or the flow of fluid is disturbed by combining at least two of the display unit 9, the light emitting means, and the sound output means. You may make it alert | report that there exists.

  Further, the notification control unit 88 may output information indicating that the fluid flow is disturbed to at least one of the analog output unit 50 and the digital communication unit 60. This makes it possible to notify the external device connected to the vortex flowmeter 1 of the fluid flow disturbance. Further, in this case, the notification control unit 88 may display a specific value such as “0” (zero) or “999” on the display unit 9 as the fluid flow rate.

On the other hand, if the result of determination in S107 is that there is a change from the previous alternating flow, the average value calculation unit 87 calculates the average value AV for all flow velocities FV included in the current update cycle UT _n ( S113), the calculated average value AV is written in the memory 7.

After S111 step, or after the S113 step, the flow rate calculating unit 89, the average value AV and _n, the channel cross-sectional area in the current update cycle UT _n calculated by the average value calculating section 87 in S109 or S111 The volume flow rate Q of the fluid is calculated using a predetermined coefficient such as a coefficient determined based on (S114), and the calculated volume flow rate Q is written in the memory 7. The memory 7 additionally stores the volume flow rate Q in time series every time the step of S114 is performed, and the central control unit 8 uses the subscript n to write any flow velocity Q _n (Q ₁ , Q ₂ written in the past). ,..., Q _n−1 , Q _n ) can be read from the memory 7.

The flow rate calculation unit 89 further reads all the volume flow rates Q _n stored in the memory 7 from the start of measurement (calculation) of the flow rate of the fluid, and integrates and integrates the volume flow rates Q _n. The flow rate T may be calculated.

In the present embodiment, an example is shown in which the flow rate calculation unit 89 calculates the volume flow rate Q of the fluid, but the present invention is not limited to this. For example, the vortex flowmeter 1 includes a pressure sensor that detects the pressure of the fluid, and the flow rate calculation unit 89 detects the calculated volume flow rate Q of the fluid, the pressure of the fluid detected by the pressure sensor, and the ambient temperature sensor 17. Based on the fluid temperature and
The mass flow rate of the fluid may be calculated.

  After step S114, the output control unit 83 outputs the volume flow rate Q of the fluid calculated by the flow rate calculation unit 89 in step S114 to the display unit 9 for display on the display unit 9 (S115). When the flow rate calculation unit 89 also calculates the fluid integrated flow rate T, at least one of the fluid volume flow rate Q and the fluid integrated flow rate T may be displayed.

  In the present embodiment, the example in which the output control unit 83 outputs the volume flow rate Q of the fluid to the display unit 9 in the step of S115 is shown, but the present invention is not limited to this. The output control unit 83 is provided with at least one of the analog output unit 50 and the digital communication unit 60 instead of the display unit 9 or together with the display unit 9, of the fluid volume flow rate Q and the fluid integrated flow rate T. At least one of them may be output. As a result, it is possible to output at least one of the fluid volume flow Q and the fluid integrated flow T to an external device connected to the vortex flowmeter 1.

  After the step of S112 or after the step of S115, the central control unit 8 performs a reset process S116.

  In the reset process S116, the central control unit 8 resets the time when the measurement is started in the initial process S101, and starts measuring the time again.

  After the reset process S115, the vortex flowmeter 1 performs the steps subsequent to S102 again, for example, until the power switch is cut off and stopped or a reset signal is input. As a result, the flow rate of the fluid is calculated and displayed (output) in the update cycle UT.

  As described above, according to the vortex flowmeter 1 of the present embodiment, based on the average value AV of the flow velocities FV stored in the memory 7, the vortex flowmeter 1 includes a plurality of flow velocities FV calculated by the flow velocities calculation unit 82 in the update cycle UT. At least one is selected. This makes it possible to exclude a flow rate FV having a specific value from a plurality of flow rates FV in the update period UT with reference to the average value AV of the flow rates FV calculated and stored in the past. Further, when the alternating flow determination unit 84 determines that the change in the alternating flow is within a predetermined range, the average value AV is calculated for at least one flow velocity FV selected by the calculation value selection unit 86. Is done. As a result, when the flow of the fluid flowing through the flow path 2a is disturbed (the fluid is a non-uniform flow), the average value AV is calculated for the flow velocity FV from which the unique value is excluded. By calculating (measuring) the flow rate of the fluid based on the average value AV, it becomes possible to make the change smaller (slowly and gently) than the actual flow rate. Thereby, the possibility that the flow rate of the fluid is dragged (affected) by the flow velocity FV having a specific value can be reduced, and the calculated (measured) flow rate of the fluid can be stabilized. The risk of adversely affecting the control system that performs control based on the fluid flow rate) can be reduced, and the reliability of the calculated (measured) fluid flow rate can be increased.

  Further, according to the vortex flowmeter 1 in the present embodiment, the predetermined calculation value is one of an alternating flow frequency, a flow velocity (fluid velocity) V, and a fluid flow amount. Accordingly, the predetermined calculation value can be easily calculated based on the sensor signal of the thermal flow sensor 10, and the fluid flow rate can be easily calculated from the average value of the predetermined calculation values.

  Further, according to the vortex flowmeter 1 in the present embodiment, a plurality of flow velocities FV in the update period UT are converted into a digital signal sequence based on the average value AV stored in the memory 7, and a pattern is formed on the digital signal sequence. Recognition processing S110 is performed. Here, when the flow rate (velocity) of the fluid is changing, the time-series change of the flow velocity FV can be classified into some specific patterns based on the average value AV of the past flow velocity FV. . Similarly, when there is a sudden turbulence in the flow of the fluid flowing through the flow path 2a, the time-series change of the flow velocity FV is also different from the average value AV of the past flow velocity FV. Can be classified into specific patterns. On the other hand, by converting the time-series change of the flow velocity FV into a digital signal sequence, it is easy to determine whether or not these specific patterns are matched (matched). Therefore, by converting a plurality of flow velocities FV in the update period UT into a digital signal sequence based on the average value AV stored in the memory 7, and performing pattern recognition processing S110 on the digital signal sequence, the flow rate of fluid ( It becomes possible to select the flow velocity FV when the (velocity) is changing more accurately and to exclude the flow velocity FV having a specific value more accurately. As a result, the accuracy of the calculated (measured) fluid flow rate can be improved, and the possibility that the fluid flow rate may be dragged (affected) by a specific value of the flow velocity FV can be further reduced. ) Can stabilize the flow rate of the fluid.

[Second Embodiment]
19 to 23 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. 19 is a partial cross-sectional view of the vortex flowmeter 1A according to the second embodiment of the present invention, and FIG. 20 is a block diagram showing a functional configuration of the vortex flowmeter 1A shown in FIG. As shown in FIG. 19, the vortex flowmeter 1 </ b> A according to 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. As shown in FIG. 20, the pressure of the fluid detected by the pressure sensor 39 is input to the central control unit 8A.

  FIG. 21 is a block diagram showing a functional configuration of the central control unit 8A shown in FIG. As shown in FIG. 21, the central control unit 8A includes an alternating frequency calculation unit 81, a flow velocity calculation unit 82, an output control unit 83, an alternating flow determination unit 84, a digital signal conversion unit 85A, and a calculation value selection unit. 86, an average value calculation unit 87, a moving average value calculation unit 90, a notification control unit 88, and a flow rate calculation unit 89.

  The digital signal converter 85A converts a plurality of flow velocities FV into digital signal sequences based on the moving average value MAV of the flow velocities FV calculated by the moving average value calculator 90 described later and stored in the memory 7.

  The calculation value selection unit 86A selects at least one of the plurality of flow rates FV calculated by the flow rate calculation unit 82 in the update period UT based on the moving average value MAV of the flow rate FV stored in the memory 7. .

  The moving average value calculation unit 90 calculates a moving average value MAV for an average value AV of a predetermined number of flow velocities FV stored in the memory 7 and writes the calculated average value MAV to the memory 7.

  The flow rate calculation unit 89A calculates the flow rate of the fluid based on the moving average value MAV of the flow velocity FV calculated by the moving average value calculation unit 90.

  Next, the operation in which the flow meter 1A shown in FIG. 19 measures (calculates) the flow rate of the fluid will be described.

  FIG. 22 is a flowchart for explaining an operation in which the vortex flowmeter 1A shown in FIG. 19 measures (calculates) the flow rate of the fluid. The vortex flowmeter 1A executes the flow rate measurement process S200 when measuring the flow rate of the fluid flowing through the flow path 2a. That is, first, the central control unit 8 performs an initial process S101 in the same manner as the flow rate measurement process S100 of the first embodiment shown in FIG.

  After the initial process S101, the pressure sensor 39 detects the pressure of the fluid (S201), and the vortex flowmeter 1A performs each step of S102 to S108 in the same manner as the flow rate measurement process S100 of the first embodiment shown in FIG. I do.

As a result of the determination in S108, when the change in the alternating flow is within a predetermined range, the digital signal converter 85A reads the flow velocity FV and a moving average value MAV described later from the memory 7, and based on the moving average value MAV. The plurality of flow velocities FV included in the current update cycle UT _n are converted into digital signal sequences (S202).

FIG. 23 is a graph for explaining a digital signal sequence converted by the digital conversion unit 85A shown in FIG. As shown in FIG. 23, similarly to the example of the first embodiment shown in FIG. 18, the flow velocity FV is calculated by the detection cycle dt, and a plurality of, for example, 18 flow velocity in FIG. FV is included. In step or S205 step S204 to be described later, the moving average value MAV _n-1 flow rate FV is calculated in the previous update cycle UT _n-1, is stored in the memory 7. The moving average value MAV is set with a predetermined range (width) Δ, for example, ± 5 [%] in the initial process S101. Therefore, for example, when the moving average value MAV _n-1 is 100 [m / s], the predetermined range (width) Δ of the moving average value MAV _n-1 is 95 [m / s] or more and 105 [m / s]. s] is as follows. In this state, the digital signal conversion unit 85A compares the predetermined range (width) Δ of the moving average value MAV _n−1 with each flow velocity FV included in the current update period UT _n , and the flow velocity FV is the moving average value MAV. if _n-1 of a predetermined range (width) is within delta to "0", if the predetermined range (width) delta outside of the flow velocity FV is the moving average value MAV _n-1 to "1", it converts respectively. For example, in the example shown in FIG. 23, the fifth, sixth, and twelfth flow velocities FV shaded in FIG. 23 are within a predetermined range (width) Δ of the moving average value MAV _n−1 . Out of range. In this case, the plurality of flow velocities FV included in the current update cycle UT _n are converted into a digital signal string “000011000001000000”.

  After step S202, the calculation value selection unit 86A performs pattern recognition processing on the digital signal sequence converted in step S202 (S203). In the pattern recognition process S203, the calculation value selection unit 86A determines whether the digital signal sequence corresponds to a predetermined pattern, and selects at least one flow velocity FV from the digital signal sequence based on the determination result.

  Here, when the flow rate (velocity) of the fluid is changing, the time-series changes of the flow velocity FV are based on the moving average value MAV of the past flow velocity FV, as in the case of the average value AV. Can be classified into specific patterns. Similarly, when there is a sudden turbulence in the flow of the fluid flowing through the flow path 2a, the time-series change of the flow velocity FV is similarly determined based on the moving average value MAV of the past flow velocity FV. As in, it can be classified into some other specific pattern. On the other hand, by converting the time-series change of the flow velocity FV into a digital signal sequence, it is easy to determine whether or not these specific patterns are matched (matched). Therefore, by converting the plurality of flow velocities FV in the update cycle UT into a digital signal sequence based on the moving average value MAV stored in the memory 7, and performing pattern recognition processing S203 on the digital signal sequence, the flow rate of the fluid It becomes possible to select the flow velocity FV when the (velocity) changes more accurately and to exclude the flow velocity FV having a specific value more accurately.

Specifically, for example, in the digital signal sequence, when “1” continues for a predetermined number, for example, three or more like “......... 11”, the actual flow velocity is the moving average in the current update cycle UT _n . It is considered that the value MAV changes beyond a predetermined range (width) Δ. Even if “1” is not continuous, if “1” continues for a predetermined number, for example, three or more, with “01” in between, for example “... in UT _n, it is believed that the actual flow rate is varied near the predetermined range (width) delta of the moving average value MAV. Further, even when “1” is included in the digital signal sequence at a predetermined ratio, for example, 50 [%] or more, it is considered that the actual flow velocity changes beyond the predetermined range (width) Δ of the moving average value MAV. It is done. Therefore, when the digital signal sequence has these patterns, the flow rate exceeds the predetermined range (width) Δ of the moving average value MAV because the actual flow rate (velocity) of the fluid has changed. The selection unit 86A selects all the flow velocities FV corresponding to the digital signal sequence.

On the other hand, for example, in a digital signal sequence, “1” is not continuous by a predetermined number, for example, 3 or more, such as “... 01000110. Is included in a predetermined ratio, for example, 20 [%] or less, in the current update cycle UT _n , there is a sudden disturbance in the flow of the fluid flowing through the flow path 2a (the fluid is suddenly uneven). It is thought that the Therefore, when the digital signal sequence has these patterns, the calculation value selection unit 86 selects the flow velocity FV corresponding to “0” and excludes the flow velocity FV corresponding to “1” in the digital signal sequence. In the case of the example shown in FIG. 23, the digital signal sequence is “000011000001000000”, and there is a sudden disturbance in the flow of the fluid flowing through the flow path 2a (the fluid suddenly becomes an uneven flow). Since it is conceivable, the calculation value selection unit 86A selects other flow velocities FV by excluding the fifth, sixth, and twelfth flow velocities FV.

  After the step of S203, the vortex flowmeter 1A performs the step of S111 in the same manner as the flow rate measurement process S100 of the first embodiment shown in FIG.

After the step of S111, the moving average value calculation unit 90 reads the average value AV from the memory 7, calculates the moving average value MAV with respect to the latest i times (i is a positive integer) average value AV. (S204), the calculated moving average value MAV is written in the memory 7. The memory 7 additionally stores the moving average value MAV in time series every time the step S204 or the later-described step S205 is performed, and the central control unit 8A uses the subscript n to store any average written in the past. The values MAV _n (MAV ₁ , MAV ₂ ,..., MAV _n−1 , MAV _n ) can be read from the memory 7. As a result, the moving average value MAV is calculated with respect to the average value AV of the flow velocity FV calculated and stored from a certain point in the past, and the flow rate of the fluid is calculated based on the moving average value MAV ( By measuring), it becomes possible to make the change even smaller (slowly and gently) than the actual flow rate.

  On the other hand, as a result of the determination in S108, when the change in the alternating flow is not within the predetermined range, that is, when the change exceeds the predetermined range, the vortex flowmeter 1A performs the flow rate of the first embodiment shown in FIG. Similar to the measurement process S100, step S112 is performed.

  On the other hand, as a result of the determination in S107, when the flow changes from the previous alternating flow, the vortex flowmeter 1A performs the step of S113 in the same manner as the flow measurement process S100 of the first embodiment shown in FIG.

  After step S113, the moving average value calculation unit 90 reads the average value AV from the memory 7 and calculates the moving average value MAV for the latest j times (j is a positive integer) average value AV. (S205), the calculated moving average value MAV is written in the memory 7.

  It is preferable that i times that is the number of the latest average value AV in step S204 is larger than j times that is the number of the latest average value AV in step S205 (i> j). Thereby, when the flow of the fluid flowing through the flow path 2a is disturbed (the fluid is a non-uniform flow), the flow of the fluid flowing through the flow path 2a is not disturbed (the fluid is a uniform flow) ) Since the number of samples (sample number) of the moving average value MAV increases, the moving average value MAV of the flow velocity FV is smoothed.

The moving average value MAV calculated by the moving average value calculating unit 90 is not limited to a simple moving average value, and may be a weighted moving average value, for example. in this case,
The calculation of the weighted moving average value in the step of S204 is preferably different from the calculation of the weighted moving average value in the step of S205. Thereby, when the flow of the fluid flowing through the flow path 2a is disturbed (the fluid is a non-uniform flow), the flow of the fluid flowing through the flow path 2a is not disturbed (the fluid is a uniform flow) ) From time to time, it is possible to further smooth the moving average value MAV of the flow velocity FV by reducing the weight of the latest (immediately previous) average value AV.

After the step of S204 or after the step of S205, the flow rate calculation unit 89A performs the moving average value MAV _n in the current update cycle UT _n calculated by the moving average value calculation unit 90 in the step of S203 or the step of S204. The volume flow rate Q of the fluid is calculated using a predetermined coefficient such as a coefficient determined based on the flow path cross-sectional area (S206), and the calculated volume flow rate Q is written in the memory 7. The memory 7 additionally stores the volume flow rate Q in time series every time the step of S206 is performed, and the central control unit 8 uses the subscript n to write any flow velocity Q _n (Q ₁ , Q ₂ written in the past). ,..., Q _n−1 , Q _n ) can be read from the memory 7.

The flow rate calculation unit 89A is further based on the calculated volume flow rate Q 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. Thus, the mass flow rate of the fluid may be calculated. Further, the flow rate calculation unit 89A further reads out all the volume flow rates Q _n stored in the memory 7 from the start of measurement (calculation) of the flow rate of the fluid, and integrates and integrates the volume flow rates Q _n. The flow rate T may be calculated.

  After the step of S206, the vortex flowmeter 1A performs the steps of S115 and S116 in the same manner as the flow rate measurement process S100 of the first embodiment shown in FIG.

  Thus, according to the vortex flowmeter 1A in the present embodiment, the moving average value MVA is calculated with respect to the predetermined number of average values AV stored in the memory 7. As a result, the moving average value MAV is calculated with respect to the average value AV of the flow velocity FV calculated and stored from a certain point in the past, and the flow rate of the fluid is calculated based on the moving average value MAV ( By measuring), it becomes possible to make the change even smaller (slowly and gently) than the actual flow rate. As a result, the possibility that the flow rate of the fluid is dragged (affected) by the flow velocity FV having a specific value can be further reduced, and the calculated (measured) flow rate of the fluid can be further stabilized.

  Further, according to the vortex flowmeter 1A of the present embodiment, when the alternating flow determination unit 84 determines that the change in the alternating flow is within a predetermined range, the change in the alternating flow is less than the predetermined range. The above-mentioned predetermined number is larger than when. Thereby, when the flow of the fluid flowing through the flow path 2a is disturbed (the fluid is a non-uniform flow), the flow of the fluid flowing through the flow path 2a is not disturbed (the fluid is a uniform flow) ) Since the number of samples (sample number) of the moving average value MAV increases, the moving average value MAV of the flow velocity FV is further smoothed. Thus, by calculating (measuring) the flow rate of the fluid based on this moving average value MAV, it becomes possible to make the change even smaller (slowly and gently) than the actual flow rate, and calculate (measure) it. The flow rate of the fluid can be further stabilized.

  Further, according to the vortex flowmeter 1A in the present embodiment, the moving average MAV calculated by the moving average value calculation unit 90 is a weighted moving average, and the alternating flow determination unit 84 changes the alternating flow to a level within a predetermined range. When it is determined that the change of the alternating flow is less than a predetermined range level, the weighting is changed. Thereby, when the flow of the fluid flowing through the flow path 2a is disturbed (the fluid is a non-uniform flow), the flow of the fluid flowing through the flow path 2a is not disturbed (the fluid is a uniform flow) ) From time to time, it is possible to further smooth the moving average value MAV of the flow velocity FV by reducing the weight of the latest (immediately previous) average value AV. Thus, by calculating (measuring) the flow rate of the fluid based on this moving average value MAV, it becomes possible to make the change even smaller (slowly and gently) than the actual flow rate, and calculate (measure) it. The flow rate of the fluid can be further stabilized.

  Further, according to the vortex flowmeter 1A in the present embodiment, the moving average value MAV calculated by the moving average value calculation unit 90 is further stored, and the update cycle UT is based on the moving average value MAV stored in the memory 7. Are converted into a digital signal sequence. Here, when the flow rate (velocity) of the fluid is changing, the time-series changes of the flow velocity FV are based on the moving average value MAV of the past flow velocity FV, as in the case of the average value AV. Can be classified into specific patterns. Similarly, when there is a sudden turbulence in the flow of the fluid flowing through the flow path 2a, the time-series change of the flow velocity FV is similarly determined based on the moving average value MAV of the past flow velocity FV. As in, it can be classified into some other specific pattern. On the other hand, by converting the time-series change of the flow velocity FV into a digital signal sequence, it is easy to determine whether or not these specific patterns are matched (matched). Therefore, by converting the plurality of flow velocities FV in the update cycle UT into a digital signal sequence based on the moving average value MAV stored in the memory 7, and performing pattern recognition processing S203 on the digital signal sequence, the flow rate of the fluid It becomes possible to select the flow velocity FV when the (velocity) changes more accurately and to exclude the flow velocity FV having a specific value more accurately. As a result, the accuracy of the calculated (measured) fluid flow rate can be improved, and the possibility that the fluid flow rate may be dragged (affected) by a specific value of the flow velocity FV can be further reduced. ) Can stabilize the flow rate of the fluid.

  Note that the configurations of the above-described embodiments may be combined or a part of the components may be replaced. The configuration of the present invention is not limited to the above-described embodiment, 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 7 ... Memory 8, 8A ... Central control part 81 ... Alternating frequency calculation part 82 ... Flow velocity calculation part 83 ... Output control part 84 ... Alternate Flow determination unit 85, 85A ... Digital signal conversion unit 86, 86A ... Calculation value selection unit 87 ... Average value calculation unit 90 ... Moving average value calculation unit 9 ... Display unit 10 ... Thermal flow sensor

Claims (7)

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 which is provided in the bypass flow path and detects the alternating flow and outputs a detection signal based on the alternating flow;
A calculated value calculation unit that calculates a predetermined calculated value based on the detection signal output from the flow sensor;
An average value calculating unit for calculating an average value of the predetermined calculation values;
A storage unit for storing the average value calculated by the average value calculation unit;
A determination unit that determines whether the change in the alternating flow is within a predetermined range based on a detection signal output from the flow sensor;
A selection unit that selects at least one of the plurality of predetermined calculation values calculated by the calculation value calculation unit in a predetermined period based on the average value stored in the storage unit;
The average value calculation unit is configured to calculate at least one predetermined calculation value selected by the selection unit when the determination unit determines that the change in the alternating flow is within the predetermined range. A vortex flowmeter characterized by calculating an average value. The vortex flowmeter according to claim 1, wherein the predetermined calculation value is any one of a frequency of the alternating flow, a velocity of the fluid, and a flow rate of the fluid. Based on the average value stored in the storage unit, further comprising a conversion unit that converts the plurality of predetermined calculation values in the predetermined period into a digital signal sequence,
The selection unit performs a predetermined pattern recognition process on the digital signal sequence, and based on a result of the predetermined pattern recognition process, at least one of the plurality of predetermined calculation values in the predetermined period. The vortex flowmeter according to claim 1, wherein the predetermined calculation value is selected. The vortex flowmeter according to claim 1, further comprising a moving average value calculation unit that calculates a moving average value for a predetermined number of the average values stored in the storage unit. The predetermined number is larger when the change of the alternating flow is less than the level of the predetermined range when the determination unit determines that the change of the alternating flow is the level of the predetermined range. The vortex flowmeter according to claim 4. The moving average value calculated by the moving average value calculation unit is a weighted moving average value,
The moving average value calculating unit is configured such that when the determination unit determines that the change in the alternating flow is at a level within the predetermined range, the change in the alternating flow is less than the level within the predetermined range. The vortex flowmeter according to claim 4, wherein the weight is changed. The storage unit further stores the moving average value calculated by the moving average value calculation unit,
7. The conversion unit according to claim 4, wherein the conversion unit converts the plurality of predetermined operation values in the predetermined period into a digital signal sequence based on the moving average value stored in the storage unit. The vortex flowmeter according to crab.

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