JPH08240469A - Flowmeter - Google Patents

Abstract

PURPOSE: To measure flow rate in a wide flow rate range. CONSTITUTION: At a small flow rate time, a cutoff valve 41 closes an opening part 16, and a cutoff valve 43 opens a small flow rate measuring passage 17, and gas taken in from an inlet part 11 flows in the small flow rate measuring passage 17, and a flow rate and an integrating flow rate are measured on the basis of output of a flow speed sensor 18 arranged in the small flow rate measuring passage 17. At a large flow rate time, the cutoff valve 41 opens the opening part 16, and a flow rate and an integrating flow rate are measured on the basis of an average value of flow speed detected by plural flow speed sensors 291 , 292 and 293 arranged in a passage 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter capable of measuring a flow rate in a wide flow rate range.

[0002]

2. Description of the Related Art Conventionally, as a flow meter used in a gas meter or the like, a flow meter or a fluidic flow meter in which the flow velocity of a fluid flowing in a pipe is measured by a flow velocity sensor such as a hot wire flow velocity meter and the flow rate is obtained from the flow velocity. It has been known. The fluidic flowmeter is located on the downstream side of the nozzle that generates the jet.
The pair of side walls form a flow passage enlarged portion, and the return guides provided outside the side walls form a pair of feedback flow passages that guide the fluid that has passed through the nozzles to the ejection port side of the nozzles along the outside of each side wall. A phenomenon in which a fluid that has been formed and has passed through a nozzle alternately flows through a pair of feedback channels (in this application, referred to as fluidic oscillation).
Is used to measure the fluid flow rate based on the frequency and period of fluidic oscillation.

[0003]

However, the conventional fluidic flowmeter has a problem that the flow rate measurement region is not very wide. Further, in a flow meter using a conventional flow velocity sensor, the flow velocity in the pipe is different from the flow velocity distribution on the same cross section due to the difference in the pipe shape, the presence of a bent portion, a branch portion, etc., or the magnitude of the flow amount, There is a problem that the measured value of the flow velocity cannot be accurately obtained, and as a result, the measurement range of the flow rate cannot be widened.

As described above, since the conventional fluidic flowmeter does not have a wide measurement area, for example, as shown in Japanese Patent Laid-Open No. 175619/1987, large flowrates for generating and detecting fluidic oscillations are detected. There is also proposed a flow meter in which a measurement unit for air flow and a measurement unit for small flow rate are connected in series. This flow meter is provided with a bypass passage that bypasses the measuring portion for small flow rate and a valve that opens and closes the bypass passage, and when the magnitude of the differential pressure between the upstream pressure and the downstream pressure is less than the set value. Closes the valve and opens the valve when the differential pressure exceeds a set value.

However, in the flowmeter disclosed in the above publication, the valve for opening and closing the bypass passage is opened when the magnitude of the differential pressure between the upstream pressure and the downstream pressure exceeds a set value. When used as, the pressure loss increases until the valve opens at a large flow rate, which may cause gas supply failure. Further, there is a problem that when the gas has a pressure fluctuation, the fluidic oscillation is disturbed particularly in the measuring unit for a small flow rate, and the accurate flow rate cannot be measured.

The present invention has been made in view of the above problems, and a first object thereof is to provide a flow meter capable of measuring the flow rate in a wide flow rate range.

A second object of the present invention is, in addition to the above objects,
(EN) It is possible to provide a flow meter capable of reducing a pressure loss at a large flow rate and easily measuring a flow rate by reducing an influence of a pressure fluctuation at a small flow rate which is easily influenced by a pressure fluctuation. .

[0008]

A flowmeter according to claim 1, wherein a first flow path for measuring a large flow rate through which a fluid passes and a small flow rate formed in parallel with the first flow path. A second flow path for measurement, a first flow rate measurement unit that outputs a signal according to the flow rate of the fluid passing through the first flow path, and a flow rate of the fluid passing through the second flow path A second flow rate measurement unit that outputs a signal, a first cutoff valve that opens and closes the first flow path, a second cutoff valve that opens and closes the second flow path, and an output of the first flow rate measurement unit And a flow rate calculating means for calculating the flow rate based on at least one of the outputs of the second flow rate measuring section, and controlling the first shutoff valve and the second shutoff valve according to the flow rate calculated by the flow rate computing means. A state where the fluid passes through the first channel, a state where the fluid passes through the second channel, the first channel and the second channel.
And a valve control means for selecting a state in which both flow paths are closed.

In this flow meter, the first flow rate measuring section outputs a signal corresponding to the flow rate of the fluid passing through the first flow path, and the second flow rate measuring section passes through the second flow path. A signal corresponding to the flow rate of the fluid to be output is output, and the flow rate calculation means calculates the flow rate based on at least one of the output of the first flow rate measurement unit and the output of the second flow rate measurement unit.
The valve control means controls the first shutoff valve and the second shutoff valve in accordance with the flow rate calculated by the flow rate calculation means, and a state in which the fluid passes through the first flow path and a fluid flows in the second flow path. A state of passing through the passage and a state in which both the first flow passage and the second flow passage are closed are selected.

A flowmeter according to a second aspect is the flowmeter according to the first aspect, in which the second flow passage is formed to have a smaller cross-sectional area than the first flow passage, and the second flow rate measuring section has the second flow passage. It is configured to include a flow velocity sensor that detects the flow velocity of the fluid passing through the flow path.

According to a third aspect of the present invention, in the flowmeter according to the first or second aspect, the first flow rate measuring section includes a flow velocity sensor for detecting a flow velocity of the fluid passing through the first flow path. It is composed.

A flowmeter according to a fourth aspect is the flowmeter according to the first or second aspect, in which the first flow rate measuring section detects a plurality of flow rates of the fluid passing through the first flow path. When the flow rate calculation means includes a sensor and calculates the flow rate based on the output of the first flow rate measurement unit, the flow rate calculation means calculates the flow rate based on the average value of the flow rates detected by the plurality of flow rate sensors. is there.

A flowmeter according to a fifth aspect of the present invention is the flowmeter according to the second aspect, further comprising a pressure fluctuation absorbing portion provided upstream of the flow velocity sensor in the second flow path and absorbing a pressure fluctuation of the fluid. Be prepared.

In this flowmeter, when the fluid that has passed through the pressure fluctuation absorbing portion passes through the second flow path, the flow fluctuation is absorbed based on the output of the flow velocity sensor while absorbing the pressure fluctuation of the fluid by the pressure fluctuation absorbing portion. Can be measured. When the fluid passes through the first flow path, it is possible to measure the flow rate based on the output of the first flow rate measurement unit while suppressing the pressure loss of the fluid.

A flowmeter according to a sixth aspect of the present invention is the flowmeter according to the fifth aspect, wherein the pressure fluctuation absorber is provided in the container forming the fluid storage chamber and in the container so that the fluid passes through the fluid storage chamber. It is configured to have two holes.

A flowmeter according to claim 7 is the flowmeter according to claim 1, 2 or
In the flowmeter according to 5 or 6, the first flow rate measurement unit is provided in the first flow path, and a fluidic oscillation generation unit that generates fluidic oscillation by the fluid ejected from the nozzle; and the fluidic oscillation generation unit. It is configured to include a fluidic oscillation detection sensor that detects fluidic oscillation generated by the oscillation generation unit.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a flowmeter according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. The flowmeter according to the present embodiment is used as a gas meter. As shown in FIG. 1, the flow meter includes a main body 10 having an inlet portion 11 for receiving gas (gas) and an outlet portion 12 for discharging gas. A partition wall 13 is provided in the main body 10, a flow channel 14 is provided from the inlet portion 11 to the partition wall 13, and a flow channel 1 as a first flow channel for large flow rate measurement from the partition wall 13 to the outlet portion 12.
5 are provided. The partition wall 13 is provided with an opening 16. A shutoff valve 41 that opens and closes the opening 16 is provided on the upstream side of the opening 16. One end of a rod 42 is connected to the shutoff valve 40. The other end of the rod 42 is connected to an actuator 51 fixed to the main body 10. The actuator 51 drives the shutoff valve 41 via the rod 42 to open and close the opening 16.

Further, in the main body 10, from the upstream side of the partition wall 16 to the middle of the flow path 15, the flow path 15 is arranged in parallel with the flow path 15.
A small flow rate measurement flow path 17 is provided. The small flow rate measuring flow path 17 is formed to have a smaller cross-sectional area than the flow path 15. In the small flow rate measurement flow path 17, a flow rate sensor 18 that detects the flow rate of the gas passing through the small flow rate measurement flow path 17 is provided. Although not shown, the flow velocity sensor 18 has a heat generating part and two temperature sensors arranged on the upstream side and the downstream side of the heat generating part, in order to keep a constant temperature difference detected by the two temperature sensors. To find the flow rate corresponding to the flow velocity from the power supplied to the heat generating part required for
The heat generating portion is heated with a constant current or constant power, and the flow rate can be obtained from the difference in temperature detected by the two temperature sensors. A cutoff valve 43 that opens and closes the inlet of the small flow rate measurement flow path 17 is provided on the upstream side of the small flow rate measurement flow path 17. The shut-off valve 43 has a rod 4
One end of 4 is connected. The other end of the rod 44 is connected to the actuator 52 fixed to the main body 10. The actuator 52 drives the shutoff valve 43 via the rod 44 to open and close the inlet portion of the small flow rate measurement flow path 17.

A guide member insertion portion 21 communicating with the flow passage 15 is provided outside the main body 10 on the downstream side of the outlet of the small flow rate measuring flow passage 17. A cylindrical guide member 22 is inserted into the guide member insertion portion 21. The guide member 22 is formed of metal such as steel or resin. The guide member 22 is provided with a plurality of, for example, three fluid passage holes 23 ₁ , 23 ₂ , 23 ₃ along the flow direction of the gas a in a portion inserted into the flow path 15.
A plate-shaped partition portion 25 is provided in the inner hollow portion of the guide member 22 along the longitudinal direction, and a semicylindrical unit insertion portion 22 is provided on both sides of the partition portion 25 as shown in FIG.
a and 22b are provided. The partition portion 25 is also formed with _three fluid passage holes 26 ₁ , 26 ₂ , 26 ₃ corresponding to the _three fluid passage holes 23 ₁ , 23 ₂ , 23 ₃ .

At the portion of the guide member 22 located outside the main body 10, a plate-shaped index is provided along the longitudinal direction of the fluid passage holes 23 ₁ , 23 ₂ , 23 ₃ (that is, the flow direction of the gas a). A portion 24 is provided, and after inserting the guide member 22 into the guide member insertion portion 21, by looking at the index portion 24, the fluid passage holes 23 ₁ , 23 ₂ , 23 ₃ are accurately oriented in the flow direction of the gas a. You can do it. It should be noted that the index portion 24 may be any one that can determine the installation direction of the guide member 22, and may be a mark display or the like.

The guide member 22 includes a flow velocity sensor unit 2
7 is to be inserted. The flow velocity sensor unit 27 has a structure in which a columnar member made of, for example, resin is divided into two, and has two semi-columnar unit members 27.
It is composed of A and 27B. These unit members 2
7A and 27B are formed with three fluid passage holes 28 ₁ , 28 ₂ and 28 ₃ corresponding to the three fluid passage holes 23 ₁ , 23 ₂ and 23 ₃ formed in the guide member 22. . Two
Of the two unit members 27A and 27B, the unit member 27B located on the downstream side with respect to the flow direction of the gas a has a flow velocity sensor 29 ₁ , so as to face each of the fluid passage holes 23 ₁ , 23 ₂ , and 23 ₃ . 29 ₂ and 29 ₃ are provided.

FIG. 3 shows the mounting state of the flow velocity sensor unit 27 with the guide member 22 and the flow velocity sensor unit 27 taken out. The unit insertion portion 22a of the guide member 22 has one unit member 27A constituting the flow velocity sensor unit 27, and the unit insertion portion 22b has the other unit member 27 constituting the flow velocity sensor unit 27.
B is inserted respectively.

The body 10 on the downstream side of the guide member insertion portion 21 has a pressure guiding hole 30 for communicating the inside and outside of the flow path 15.
Is provided. A pressure sensor 31 that detects the pressure of the gas in the flow path 15 via the pressure guiding hole 30 is provided outside the main body 20 corresponding to the pressure guiding hole 30.

FIG. 4 is a block diagram showing the configuration of the circuit portion of the flowmeter according to this embodiment. As shown in this figure, the flowmeter includes a flow velocity calculation unit 61 that calculates the flow velocity based on the output signal of the flow velocity sensor 18, flow velocity sensors 29 ₁ , 29 ₂ ,
29 ₃ An average flow velocity calculation unit 6 that calculates the average value of the flow velocity at a plurality of positions in the flow path 15 based on the output signal of each of them.
2, a flow rate calculation unit 64 that calculates a flow rate based on at least one of the output of the flow velocity calculation unit 61 and the output of the average flow velocity calculation unit 62, and the flow rate calculated by this flow rate calculation unit 64 is integrated to obtain an integrated flow rate. An integrated flow rate calculation unit 65 for calculating,
A display unit 66 that displays the integrated flow rate calculated by the integrated flow rate calculation unit 65, and controls the actuators 51 and 52 according to the flow rate calculated by the flow rate calculation unit 64 and the output signal of the pressure sensor 31. A valve control unit 67 for displaying an alarm using the display unit 66 is provided. The flow rate calculation unit 64 calculates the flow rate by multiplying the flow velocity calculated by the flow velocity calculation unit 61 or the average value of the flow velocity calculated by the average flow velocity calculation unit 62 by a predetermined pipe shape factor. Flow velocity calculation unit 61, average flow velocity calculation unit 62, flow rate calculation unit 64, integrated flow rate calculation unit 65, and valve control unit 67.
Is composed of, for example, a microcomputer.

Next, the operation of the flowmeter according to this embodiment will be described.

Initially, as shown in FIG. 1, the shut-off valve 41
Closes the opening 16 and the shutoff valve 43 opens the small flow rate measuring flow path 17. In this state, the gas taken in from the inlet portion 11 has a small flow rate measuring flow path 17
Flow passage 2 formed in the guide member 22
3 ₁ , 23 ₂ , 23 ₃ , fluid passage holes 28 ₁ , 28 ₂ , 28 ₃ formed in the flow velocity sensor unit 27, and fluid passage holes 26 ₁ , 26 ₂ , 26 ₃ formed in the partition 25.
And is discharged from the outlet 12. Flow velocity sensor 1
8 detects the flow velocity of the gas passing through the small flow rate measuring flow path 17, and the flow velocity sensors 29 ₁ , 29 ₂ , 29 ₃ are the fluid passage holes 2
The flow velocity of the gas passing through 3 ₁ to 23 ₃ , 28 _{1 to} 28 ₃ , 26 _{1 to} 26 ₃ is detected. The flow velocity calculation unit 61 calculates the flow velocity based on the output signal of the flow velocity sensor 18, and the average flow velocity calculation unit 62 calculates the average value of the flow velocity based on the output signals of the flow velocity sensors 29 ₁ , 29 ₂ , 29 ₃ .

The flow rate calculator 64 is, for example, the flow velocity calculator 6
When the flow rate calculated based on the output of No. 1 and the output of the average flow velocity calculation unit 62 is within the flow amount range on the small flow rate side, the flow amount calculated based on the output of the average flow velocity calculation unit 62 is A signal representing the flow rate calculated based on the output of the flow velocity calculation unit 61 is output to the integrated flow rate calculation unit 65. The integrated flow rate calculation unit 65 calculates the integrated flow rate based on the output signal of the flow rate calculation unit 64, and the integrated flow rate is displayed on the display unit 66.
Displayed by. In the flow rate calculation unit 64,
The flow rate range calculated based on the output of the flow velocity calculation unit 61 is, for example, 0 to 500 liters / hour, and the flow rate range calculated based on the output of the average flow velocity calculation unit 62 is 0, for example.
~ 50 m ³ / hour.

From this state, when the flow rate is increased and the flow rate calculated by the flow rate calculation section 61 based on the output of the average flow velocity calculation section 62 enters the flow rate range on the large flow rate side, the range is set, The control unit 67 operates the actuator 51 so that the shutoff valve 41 opens the opening 16.
In this state, the gas passes through the opening 16 and the flow path 15, and the fluid passage holes 23 ₁ to 23 ₃ , 28 _{1 to} 28 ₃ ,
After passing through 26 _{1 to} 26 ₃ , it is discharged from the outlet section 12. The flow rate calculation unit 64 also outputs a signal representing the flow rate calculated based on the output of the average flow velocity calculation unit 62 to the integrated flow rate calculation unit 65.

From this state, when the flow rate decreases and enters the flow rate region on the small flow rate side again, the valve control section 67 causes the actuator 5
1 is operated so that the shutoff valve 41 closes the opening 16 and the shutoff valve 43 opens the small flow rate measurement flow path 17. In addition, the flow rate calculation unit 64 outputs a signal representing the flow rate calculated based on the output of the flow velocity calculation unit 61 to the integrated flow rate calculation unit 65.
Output to.

Further, the valve control section 67 detects that the flow rate calculating section 64 detects a flow rate of a predetermined amount or more, or detects a predetermined flow rate for a predetermined time or more, or the pressure sensor 31 makes the pressure of gas below a predetermined value. In the event of an abnormality such as when a decrease is detected, the actuators 51 and 52 are operated so that the shutoff valve 41 closes the opening 16 and the shutoff valve 43 closes the small flow rate measurement flow path 17. In this state, the flow path 1
5 and the small flow rate measurement flow path 17 are both closed, and the supply of gas to the downstream side of the flow meter is shut off. Further, the valve control unit 67 uses the display unit 66 to display an alarm when an abnormality occurs.

As described above, according to the present embodiment, the small flow rate measuring flow path 17 having a small cross-sectional area is provided in parallel with the flow path 15, and the flow rate region on the large flow rate side is provided in the flow path 15. calculating the flow rate and the integrated flow rate based on the average value of the flow velocity detected by the plurality of flow velocity sensors 29 _1, 29 _2, 29 _3, the flow rate range of small flow rate side provided on the small flow rate measuring flow path 17 Since the flow rate and the integrated flow rate are calculated based on the output of the flow velocity sensor 18, the flow rate and the integrated flow rate can be measured in a wide flow rate range. Moreover, in the flow rate region on the large flow rate side, a plurality of flow velocity sensors 29 ₁ , 29 ₂ ,
Because it calculates the flow rate based on the average value of the flow velocity detected by the 29 _3, even if the flow velocity distribution in the flow channel 15 by the flow rate magnitude such as the changes, the flow rate based on the output of one flow sensor The flow rate can be measured more accurately and the flow rate measurement range can be widened as compared with the case of calculation.

Further, in parallel with the flow path 15, a dedicated small flow rate measuring flow path 17 having a small cross-sectional area for measuring the flow rate at the time of a small flow rate is provided, and the flow paths are cut off by the shutoff valves 41 and 43 according to the flow rate. Since the gas passes through the small flow rate measuring flow path 17 at the time of the small flow rate and the gas passes through the flow path 15 having a large cross-sectional area at the time of the large flow rate without increasing the pressure loss at the time of the large flow rate. Since the flow velocity of gas at a small flow rate can be increased, the accuracy of flow rate measurement at a small flow rate can be improved.

FIG. 5 is a sectional view showing the structure of a flowmeter according to the second embodiment of the present invention. As shown in this figure, in the present embodiment, a fluidic oscillation generator 70 is provided in the flow path 15 instead of the flow velocity sensor unit 27 in the first embodiment. Fluidic oscillation generator 70
Has a nozzle 71 and a pair of side walls 73, 74 provided on the downstream side of the nozzle 71 and forming an enlarged flow path. A first target 75 is arranged on the upstream side and a second target 76 is arranged on the downstream side with a predetermined space between the side walls 73 and 74. Side walls 73,7
The gas that has passed through the nozzle 71 is provided outside each of the side walls 7
A return guide 79 is provided along the outer circumference of the nozzles 3, 74 to form a pair of feedback channels 77, 78 for returning to the ejection port side of the nozzle 71. Between each outlet portion of the feedback flow paths 77 and 78 and the outlet portion 12,
The rear surface of the return guide 79 and the main body 10 form a pair of discharge paths 81 and 82. Pressure guiding holes 83 and 84 are provided in the vicinity of the ejection port of the nozzle 71, and the main body 10
The pressure guiding hole 8 is provided outside the bottom of the
A piezoelectric film sensor 85 (not shown in FIG. 5) is provided as a fluidic oscillation detecting sensor that communicates with the pressure guiding holes 83 and 84 and that detects the pressure difference between the pressure guiding holes 83 and 84. In this embodiment, the pressure guiding hole 30 and the pressure sensor 31 are provided on the upstream side of the fluidic oscillation generator 70.

FIG. 6 is a block diagram showing the configuration of the circuit portion of the flowmeter according to this embodiment. As shown in this figure, the flow meter according to this embodiment, in place of the first flow rate sensor 29 ₁ in the embodiment of, 29 _2, 29 ₃ and the average flow velocity calculating unit 62, the piezoelectric film sensor 85, the piezoelectric Membrane sensor 85
An analog amplifier 68 that amplifies the output signal of the above-mentioned, and a waveform shaping circuit 69 that waveform-shapes the output of the analog amplifier 68 to generate a pulse. The flow rate calculation unit 64 is
For example, the flow rate is calculated based on the output of the flow velocity calculation unit 61 and the output of the waveform shaping circuit 69, and the waveform shaping circuit 69 is calculated.
When the flow rate calculated based on the output of 1 is in the flow rate region on the small flow rate side where the range is set in advance, a signal indicating the flow rate calculated based on the output of the flow velocity calculation section 61 is output to the integrated flow rate calculation section 65. When in the flow rate region on the large flow rate side, a signal representing the flow rate calculated based on the output of the waveform shaping circuit 69 is output to the integrated flow rate calculation unit 65.

In this embodiment, the gas that has passed through the opening 16 or the small flow rate measuring flow path 17 reaches the fluidic oscillation generator 70. Here, the gas that has passed through the nozzle 71 becomes a jet stream and is jetted from the jet outlet. The gas ejected from the ejection port flows along one side wall due to the Coanda effect. Here, it is assumed that the material flows first along the side wall 73. The gas flowing along the side wall 73 is further returned to the ejection port side of the nozzle 71 through the feedback flow path 77, and is discharged to the outlet section 12 through the discharge path 81. At this time, the direction of the gas ejected from the nozzle 71 is changed by the gas flowing through the feedback flow path 77, and this time the gas flows along the other side wall 74. This gas further passes through the feedback flow path 78, and the nozzle 71
Is discharged to the outlet portion 12 via the discharge passage 82. Then, the direction of the gas ejected from the nozzle 71 is changed by the gas flowing through the feedback channel 78, and the gas flows again along the side wall 73 and the feedback channel 77. By repeating the above operation, the gas that has passed through the nozzle 71 performs fluidic oscillation that alternately flows through the pair of feedback flow paths 77 and 78. The frequency of this fluidic oscillation,
The cycle has a relationship with the flow rate. The fluidic oscillation is detected by the piezoelectric film sensor 85. Flow rate calculator 64
Outputs a signal representing the flow rate calculated based on the output of the flow velocity calculating section 61 to the integrated flow rate calculating section 65 in the flow rate range on the small flow rate side, and outputs the waveform (waveform shaping) from the piezoelectric film sensor 85 in the flow rate range on the high flow rate side. A signal representing the flow rate calculated based on the output of the circuit 69) is output to the integrated flow rate calculation unit 65.

As described above, in this embodiment, the fluidic oscillation generating section 70 is provided in the flow path 15, and in the flow rate region on the large flow rate side, the flow rate and the integration are calculated based on the output of the piezoelectric film sensor 85 for detecting the fluidic oscillation. Since the flow rate is calculated, the flow rate and the integrated flow rate can be accurately obtained regardless of the flow velocity distribution in the flow path 15. Other configurations, operations and effects of this embodiment are similar to those of the first embodiment.

FIG. 7 is a sectional view showing the structure of a flowmeter according to the third embodiment of the present invention. This flowmeter includes a main body 110 having an inlet portion 111 that receives gas (gas) and an outlet portion 112 that discharges gas. Body 110
A fluidic oscillation generator 70 similar to that of the second embodiment and channels 113a and 113 for guiding the gas taken in through the inlet 111 to the fluidic oscillator generator 70 are provided therein.
b and a flow path 114 that guides the gas discharged from the fluidic oscillation generator 70 to the outlet 112.

A partition wall 115 is provided between the flow channel 113a and the flow channel 113b, and the partition wall 115 has an opening 116.
Is provided. The flow channel 113a is a flow channel closer to the inlet portion 111 than the partition wall 115, and the flow channel 113b is a partition wall 115.
Is a flow path on the fluidic oscillation generation unit 70 side.
A shutoff valve 138 that opens and closes the opening 116 is provided on the upstream side of the opening 116. One end of a rod 139 is connected to the shutoff valve 138. The other end of the rod 139 has an actuator 151 fixed to the main body 110.
It is connected to the.

In the main body 110, a small flow rate measuring flow path 117 is further provided from the upstream side of the partition wall 115 to the front side of the nozzle 71 so as to be parallel to the flow path 113b. In the small flow rate measurement flow path 117, a flow rate sensor 18 similar to that of the second embodiment for detecting the flow rate of the gas passing through the small flow rate measurement flow path 117 is provided.

A pressure fluctuation absorbing section 140 is provided upstream of the flow velocity sensor 18 in the small flow rate measuring flow path 117. The pressure fluctuation absorbing unit 140 has a container 142 that forms a gas storage chamber 143 therein, a hole 144 provided at an upstream end of the container 142, and a hole 145 provided at a downstream end of the container 142. A check valve 146 provided at a position facing the hole 144 in the container 142, a rod 147 connected to the check valve 146, and a guide 148 slidably holding the rod 147. ing. The check valve 146 is raised by the pressure of the gas passing through the hole 144 to open the hole 144, and
The backflow of gas from the inside to the outside of the hole 144 is prevented. It should be noted that the small flow rate measurement flow path 117 is the same as the flow path 1 except for the portion where the pressure fluctuation absorber 140 is provided.
The cross-sectional area is smaller than 13b.

A cutoff valve 149 for opening and closing the hole 145 is provided on the downstream side of the hole 145. One end of a rod 150 is connected to the shutoff valve 149. This rod 150
The other end side of the actuator 1 is fixed to the main body 110.
It is connected to 52.

FIG. 8 is a block diagram showing the configuration of the circuit portion of the flowmeter according to this embodiment. As shown in this figure, in the circuit configuration of the flowmeter according to the present embodiment, the valve control unit 67 is the second
The second embodiment is the same as the second embodiment except that the actuators 151 and 152 are controlled in place of the actuators 51 and 52 in this embodiment and that the pressure sensor 31 is not provided.

Next, the operation of the flowmeter according to this embodiment will be described.

Initially, as shown in FIG. 7, the shut-off valve 13
8 closes the opening 116 and the shutoff valve 149 opens the hole 145. In this state, the entrance 11
The gas taken in from No. 1 passes through the hole 144, the gas storage chamber 143, and the hole 145 of the pressure fluctuation absorbing unit 140, flows through the small flow rate measurement flow path 117, and the fluidic generation unit 7
After passing through 0, it is discharged from the outlet 112 through the flow path 114. The holes 144 and 145 of the pressure fluctuation absorbing section 140 act as a resistance, the gas storage chamber 143 corresponds to a condenser, and the pressure fluctuation absorbing section 140 constituted by the hole 144, the gas storage chamber 143, and the hole 145 functions as a high-frequency removal filter. Because of the action of the gas, the holes 144, the gas storage chamber 1
As it passes through 43 and hole 145, pressure fluctuations of the gas are absorbed. The flow velocity sensor 18 has a small flow rate measuring channel 117.
The flow velocity of the gas passing through is detected. The flow rate calculation unit 64 is
In the flow rate region on the small flow rate side where the range is set in advance, the flow rate is calculated based on the output of the flow velocity sensor 18 (output of the flow velocity calculation unit 61).

From this state, when the flow rate increases and exceeds the predetermined value to reach the flow rate region on the large flow rate side where the range is set in advance,
The valve control unit 67 operates the actuator 151 so that the shutoff valve 138 opens the opening 116. In this state, the gas passes through the opening 116 and the flow path 113b.
To reach the fluidic generator 70. The fluidic generated by the fluidic generator 70 is detected by the piezoelectric film sensor 85. The flow rate calculation unit 64 is
In the flow rate region on the large flow rate side, the flow rate is calculated based on the output of the piezoelectric film sensor 85 (output of the waveform shaping circuit 69).

From this state, when the flow rate decreases and returns to the flow rate region on the small flow rate side, the valve control unit 67 causes the actuator 1
51 is operated so that the cutoff valve 138 closes the opening 116 and the cutoff valve 149 opens the hole 145. Further, the flow rate calculation unit 64 calculates the flow rate based on the output of the flow velocity sensor 18 (output of the flow velocity calculation unit 61).

Further, the valve control unit 67 is arranged so that the actuator 15 can be operated in the event of an abnormality such as when the flow rate calculation unit 64 detects a flow rate of a predetermined amount or more, or when the flow rate is detected for a predetermined time or more.
1, 152 are operated so that the shutoff valve 138 closes the opening 116 and the shutoff valve 149 closes the hole 145.
In this state, the flow path 113b and the small flow rate measurement flow path 117 are provided.
Are closed together, and the supply of gas to the downstream side of the flow meter is shut off.

As described above, according to the present embodiment, the small flow rate measuring flow path 117 having a small cross-sectional area is provided in parallel with the flow path 113b reaching the fluidic oscillation generator 70, and the small flow rate measuring flow path is provided. The flow velocity sensor 18 is provided in the path 117, the flow rate is calculated based on the output of the piezoelectric film sensor 85 that detects fluidic oscillation in the flow rate range on the large flow rate side, and the flow rate sensor 18 outputs the flow rate sensor 18 in the flow rate range on the small flow rate side. Since the flow rate is calculated based on this, the flow rate can be measured in a wide flow rate range. In addition, the shutoff valves 138, 14 are
The flow path is switched by 9 so that the gas passes through the flow path 113b having a large cross-sectional area at a large flow rate, so that the gas supply failure due to the pressure decrease does not occur.

Further, since the gas is made to pass through the pressure fluctuation absorbing portion 140 at the time of the small flow rate, the influence of the pressure fluctuation can be reduced at the time of the small flow rate which is easily affected by the pressure fluctuation, and the accuracy of the flow rate measurement can be improved. be able to.

Further, since the dedicated small flow rate measuring flow path 117 having a small cross-sectional area for measuring the flow rate at the small flow rate is provided, the gas loss at the small flow rate is increased without increasing the pressure loss at the large flow rate. Since the flow velocity can be increased, the accuracy of flow rate measurement at a small flow rate can be improved. Other configurations, operations and effects of this embodiment are similar to those of the second embodiment.

The present invention is not limited to the above embodiments, and for example, instead of the flow velocity sensor 18 in the small flow rate measuring flow paths 17 and 117, a fluidic oscillation generating section for measuring a small flow rate and a piezoelectric film. A sensor may be provided. Further, the flow velocity sensor is not limited to the one having the heat generating portion and the two temperature sensors, and for example, the heat generating portion having one heat generating portion and necessary for keeping the temperature (resistance) of the heat generating portion constant. The flow velocity may be obtained from the supplied power, or the heat generating portion may be heated with a constant current or constant power and the flow velocity may be determined from the temperature (resistance) of the heat generating portion.

Further, the present invention can be applied to a flow meter for measuring the flow rate of not only gas but also liquid.

[0054]

As described above, according to the flowmeter according to any one of claims 1 to 7, the first flow path for measuring a large flow rate and the second flow path for measuring a small flow rate are provided. And a first flow rate measuring unit that outputs a signal according to the flow rate of the fluid passing through the first flow path, and a second flow rate that outputs a signal according to the flow rate of the fluid passing through the second flow path. A measurement unit, a first cutoff valve that opens and closes the first flow path, and a second cutoff valve that opens and closes the second flow path are provided, and the valve control means controls the first cutoff valve according to the flow rate. And a second cutoff valve are controlled so that the fluid passes through the first flow path and the fluid passes through the second flow path.
And a state in which both the second flow channel and the second flow channel are closed, and the flow rate calculation unit determines whether the flow rate calculation unit is based on at least one of the output of the first flow rate measurement unit and the output of the second flow rate measurement unit. Since the flow rate is calculated, there is an effect that the flow rate can be measured in a wide flow rate range.

According to the flowmeter of the fourth aspect, the first flow rate measuring section includes a plurality of flow rate sensors for detecting the flow rate of the fluid passing through the first flow path at a plurality of points, and the flow rate calculating means. When the flow rate is calculated based on the output of the first flow rate measuring unit, the flow rate is calculated based on the average value of the flow rates detected by the plurality of flow rate sensors. The effect is that the flow rate on the large flow rate side can be measured more accurately.

According to the flowmeter of the fifth or sixth aspect, in the state where the fluid passing through the pressure fluctuation absorbing section passes through the second flow path, the pressure fluctuation absorbing section absorbs the pressure fluctuation of the fluid. However, it becomes possible to measure the flow rate based on the output of the flow velocity sensor, and in the state where the fluid passes through the first flow path, while suppressing the pressure loss of the fluid, based on the output of the first flow rate measurement unit. It becomes possible to measure the flow rate, and in addition to the above-mentioned first effect, it is possible to reduce the pressure loss at the time of a large flow rate, and reduce the influence of the pressure fluctuation at the time of a small flow rate which is easily affected by the pressure fluctuation. There is an effect that the flow rate can be accurately measured.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a flow meter according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an exploded perspective view showing a guide member and a flow velocity sensor unit of the flow meter shown in FIG. 1, taken out.

FIG. 4 is a block diagram showing a circuit configuration of a flowmeter according to the first embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of a flow meter according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a circuit configuration of a flowmeter according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing a configuration of a flow meter according to a third embodiment of the present invention.

FIG. 8 is a block diagram showing a circuit configuration of a flowmeter according to a third embodiment of the present invention.

[Explanation of symbols]

14, 15 Flow path 17 Small flow rate measurement flow path 18, 29 ₁ , 29 ₂ , 29 ₃ Flow velocity sensor 41, 43 Shut-off valve 51, 52 Actuator 61 Flow velocity calculation unit 62 Average flow velocity calculation unit 64 Flow rate calculation unit 67 Valve control unit

Continuation of the front page (72) Inventor Kiichi Suyama 3-3, Shiomidai, Isogo-ku, Yokohama, Kanagawa Prefecture, 3305, Room 514, Room 372 (72) Inventor, Sobun Sato 2-11-2, Kajigaya, Takatsu-ku, Kawasaki-shi, Kanagawa (72) Invention Sato Shinichi 543-15 Kitano-cho, Hachioji-shi, Tokyo

Claims (7)

[Claims] 1. A first flow path for measuring a large flow rate through which a fluid passes, a second flow path for measuring a small flow rate which is formed in parallel with the first flow path, and the first flow path. A first flow rate measuring unit for outputting a signal according to the flow rate of the fluid passing through the second flow path, and a second flow rate measuring unit for outputting a signal according to the flow rate of the fluid passing through the second flow path. A first shutoff valve that opens and closes the first flow path, a second shutoff valve that opens and closes the second flow path, an output of the first flow rate measurement unit, and the second flow rate measurement unit Flow rate calculation means for calculating a flow rate based on at least one of the outputs of the first and second cutoff valves in accordance with the flow rate calculated by the flow rate calculation means, so that the fluid becomes the first State where the first passage and the second passage are closed, a state where the fluid passes through the second passage, a state where the fluid passes through the second passage, and a state where both the first passage and the second passage are closed. Flowmeter is characterized in that a valve control means for selecting and. 2. The second flow passage is formed to have a smaller cross-sectional area than the first flow passage, and the second flow rate measuring unit detects a flow velocity of a fluid passing through the second flow passage. The flowmeter according to claim 1, further comprising: 3. The flowmeter according to claim 1, wherein the first flow rate measuring unit includes a flow velocity sensor that detects a flow velocity of the fluid passing through the first flow path. 4. The first flow rate measuring section includes a plurality of flow rate sensors for detecting a flow rate of a fluid passing through the first flow path at a plurality of locations, and the flow rate calculating means outputs the output of the first flow rate measuring section. The flowmeter according to claim 1, wherein the flowrate is calculated based on an average value of the flowrates detected by the plurality of flowrate sensors when the flowrate is calculated based on the flowrate. 5. The flow meter according to claim 2, further comprising a pressure fluctuation absorbing section that is provided in the second flow path upstream of the flow velocity sensor and that absorbs a pressure fluctuation of the fluid. . 6. The pressure fluctuation absorbing section has a container forming a fluid storage chamber, and two holes provided in the container so that a fluid passes through the fluid storage chamber. Item 5. The flowmeter according to item 5. 7. The first flow rate measurement unit is provided in the first flow path, and generates a fluidic oscillation by a fluid ejected from a nozzle, and a fluidic oscillation generation unit. 7. A flowmeter according to claim 1, 2, 5 or 6, further comprising a fluidic oscillation detection sensor that detects fluidic oscillation generated by the above.