JPH0968448A - Flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flowmeter by which a flow rate can be measured over a wide flow-rate range. SOLUTION: In a pipe 10, a flow passage 13 for large-flow-rate measurement and a flow passage 14, for small-flow-rate measurement, which is formed in series on the downstream side of the flow passage 13 for large-flow-rate measurement and whose cross-sectional area is smaller than that of the flow passage 13 for large-flow-rate measurement are formed. A plurality of flow-velocity sensors are installed respectively inside the flow passage 13 for large-flow-rate measurement and inside the flow passage 14 for small-flow-rate measurement. In a small-flow-rate region, a flow rate is computed on the basis of outputs of flow-velocity sensors 292 , 293 inside the flow passage 14 for small-flow-rate measurement. In a large-flow-rate region, a flow rate is computed on the basis of outputs of flow-velocity sensors 291 , 292 , 293 inside the flow passage 13 for large-flow-rate measurement.

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 Flowmeters used for gas meters, etc.
In some systems, the flow velocity of the fluid flowing through the pipe is detected, the flow rate is calculated from the flow velocity, and this is displayed. Further, as a method for detecting the flow velocity, there are a thermal type, a differential pressure type, a rotary type and the like.

Here, in the conventional flowmeter, as shown in FIG. 21, for example, one flow velocity sensor 1 is arranged in the central portion of the fluid flow path in the pipe 2, and the flow rate calculation unit 3
A flow rate is calculated by multiplying the flow rate at the center of the flow path obtained by the flow rate sensor 1 by the cross-sectional area of the pipe 2, and the flow rate is displayed on the display unit 4.

[0004]

However, the piping 2
Among them, there is a problem that it is difficult to determine the mounting position of the flow velocity sensor 3, because a drift occurs depending on the flow rate. In order to maintain high flow rate measurement accuracy,
There is a problem that the flow rate measurement range needs to be limited to a flow rate range with less uneven flow, and the flow rate measurement range is narrowed.

The flow meter also has a throttle type flow meter that determines the flow rate from the pressure difference before and after the throttle. However, in this throttle type flow meter, the pressure loss due to the throttle is large, and when used as a gas meter, Supply failure may occur.

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

[0007]

According to a first aspect of the present invention, there is provided a flowmeter which is provided in series with a first flow passage for measuring a large flow rate through which a fluid passes, and the first flow passage. Second flow path for measuring a small flow rate having a smaller cross-sectional area than the flow path of the first flow path, a first flow rate sensor that outputs a signal according to the flow rate of the fluid passing through the first flow path, and a second flow rate A second flow velocity sensor that outputs a signal according to the flow velocity of the fluid passing through the passage, and according to the flow rate,
The flow rate calculating means calculates a flow rate based on at least one of the output signal of the first flow velocity sensor and the output signal of the second flow velocity sensor.

In this flowmeter, the first flow velocity sensor outputs a signal corresponding to the flow velocity of the fluid passing through the first flow passage for large flow measurement, and the second flow velocity sensor outputs the first flow velocity signal. A signal corresponding to the flow velocity of the fluid passing through the second flow passage for measuring a small flow rate having a smaller cross-sectional area than the passage is output, and the flow rate calculation means outputs the output signal of the first flow velocity sensor according to the flow rate. The flow rate is calculated based on at least one of the output signals of the second flow velocity sensor.

According to a second aspect of the present invention, in the flowmeter according to the first aspect, a plurality of first flow velocity sensors are provided in the first flow path, and the first flow velocity sensor outputs the first flow velocity sensor from the output signals of the first flow velocity sensors.
It further comprises a first flow passage average flow velocity calculating means for calculating the average value of the flow velocity in the flow passage and outputting it to the flow rate calculating means.

In this flowmeter, the average value of the flow velocity in the first flow passage is calculated from the output signals of the plurality of first flow velocity sensors by the first flow passage average flow velocity calculating means. Based on this, the flow rate calculation means calculates the flow rate.

According to a third aspect of the present invention, there is provided the flowmeter according to the second aspect, wherein the plurality of first flow velocity sensors are respectively first.
It is configured so as to be arranged in the central portion in the channel.

A flowmeter according to a fourth aspect is the flowmeter according to the third aspect, wherein a guide member insertion portion is provided so as to penetrate a wall surface along a longitudinal direction of the pipe forming the first flow path, A hollow guide member that is inserted into the pipe through the guide member insertion portion and has a plurality of first fluid passage holes along the fluid flow direction, and is inserted into the guide member, and A flow velocity sensor unit having a plurality of second fluid passage holes corresponding to the plurality of first fluid passage holes of the guide member, and the plurality of first flow velocity sensors respectively include a plurality of flow velocity sensor units. It is arranged so as to face each of the two fluid passage holes.

According to a fifth aspect of the present invention, in the flowmeter according to the second aspect, a plurality of second flow velocity sensors are provided in the second flow path, and a second flow velocity sensor is provided with a second flow velocity sensor based on output signals of the plurality of second flow velocity sensors.
The second flow rate average flow velocity calculating means for calculating the average value of the flow velocity in the flow path and outputting it to the flow rate calculating means.

In this flowmeter, the average value of the flow velocity in the second flow passage is calculated from the output signals of the plurality of second flow velocity sensors by the second flow passage average flow velocity calculating means. Based on this, the flow rate calculation means calculates the flow rate.

According to a sixth aspect of the present invention, in the flowmeter according to the fifth aspect, a guide member insertion portion is provided so as to penetrate a wall surface along a longitudinal direction of a pipe forming the second flow path, A hollow guide member that is inserted into the pipe through the guide member insertion portion and that has a plurality of first fluid passage holes along the fluid flow direction, and is inserted into the guide member and guides. A second flow velocity sensor unit having a plurality of second fluid passage holes corresponding to the plurality of first fluid passage holes of the member, and the plurality of second flow velocity sensors respectively include a plurality of second flow velocity sensor units with respect to the second flow velocity sensor unit. It is arranged so as to face each of the fluid passage holes.

According to a seventh aspect of the present invention, there is provided a flowmeter according to the fifth aspect, wherein the plurality of first flow velocity sensors are respectively first.
It is configured to be arranged at a predetermined interval on the wall surface along the cross section in the direction orthogonal to the longitudinal direction of the pipe forming the channel.

A flowmeter according to an eighth aspect is the flowmeter according to the seventh aspect, further comprising a plurality of second flow velocity sensors in a direction orthogonal to the longitudinal direction of the pipe forming the second flow path. It is configured to be arranged at a predetermined interval on the wall surface along the cross section.

A flowmeter according to a ninth aspect is the flowmeter according to the eighth aspect, wherein each of the plurality of second flow velocity sensors is a second one.
The first flow rate sensor and the first flow rate sensor are arranged so as to be displaced from each other by a predetermined angle when viewed in the longitudinal direction of the pipe constituting the channel.

According to a tenth aspect of the present invention, in the flowmeter according to the ninth aspect, the second flow passage is arranged on the downstream side of the first flow passage, and a plurality of second flow velocity sensors are provided respectively. It is configured to be arranged within a range of a distance of ½ of the inner diameter of the second flow path from the boundary position between the first flow path and the second flow path.

A flowmeter according to an eleventh aspect of the present invention is the flowmeter according to the fifth aspect, wherein an overlapping flow rate region is provided in which both the first flow velocity sensor and the second flow velocity sensor can measure, and in this overlapping flow rate region, The flow rate calculation means calculates the flow rate calculated from the first average flow rate value output from the first flow path average flow rate calculation means and the second average flow rate calculated from the second flow path average flow rate calculation means. It is configured such that the average value with the flow rate calculated from the flow velocity value is used as the measured flow rate.

According to a twelfth aspect of the present invention, in the flow meter according to the first aspect, an output of either one of the first flow velocity sensor of the first flow passage and the second flow velocity sensor of the second flow passage. In the flow rate range in which the flow rate is calculated using, the power supply to the other flow velocity sensor is cut off.

According to a thirteenth aspect of the present invention, in the flowmeter according to any one of the second to sixth aspects, in the upstream side of the first flow velocity sensor in the first flow passage and in the second flow passage. The present invention is configured to further include a rectifying member that is provided on the upstream side of the second flow velocity sensor and that regulates the flow of fluid, whereby the flow of gas when passing through the flow velocity sensor is regulated, and more accurately. The flow rate can be measured.

The flowmeter according to claim 14 is the flowmeter according to any one of claims 7 to 10, wherein the flowmeter is provided upstream of the first flow velocity sensor in the first flow path.
It is configured to further include a rectifying member that regulates the flow of fluid.

[0024]

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

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
2 is a sectional view showing the configuration of the flow meter according to the embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. The flow meter according to the present embodiment is used as a gas meter. This flowmeter has an inlet part 1 for receiving a gas.
1 is provided with a pipe 10 having an outlet 12 for discharging gas. The pipe 10 includes a large flow rate measurement flow path 13,
It is provided in series on the downstream side of the large flow rate measurement channel 13,
A small flow rate measurement flow path 14 having a smaller cross-sectional area than the large flow rate measurement flow path 13 is formed. The diameter of the large flow rate measurement flow path 13 is, for example, 80 mm, the diameter of the small flow rate measurement flow path 14 is, for example, 32 mm, and the pipe 10 on the upstream side of the large flow rate measurement flow path 13 is used.
The diameter of is 50 mm, for example.

In the pipe 10, a large flow rate measurement flow path 13 and a small flow rate measurement flow path 13 are provided outside the portion forming the large flow rate measurement flow path 13 and outside the portion forming the small flow rate measurement flow path 14, respectively. A guide member insertion portion 21 that communicates with the working channel 14 is provided. 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. This guide member 2
A plurality of, for example, three fluid passage holes 23 ₁ , 23 ₂ , and 23 ₃ are provided in ₂ along the flow direction of the gas a.
The guide member 22 on the side of the large flow rate measurement channel 13 has 3
The fluid passage holes 23 ₁ , 23 ₂ , 23 ₃ are inserted into the large flow rate measurement flow path 13, and the two fluid passage holes 23 ₂ , 23 ₃ are provided in the guide member 22 on the small flow rate measurement flow path 14 side.
Is inserted in the small flow rate measurement flow path 14. A plate-shaped partition portion 25 is provided in the inner hollow portion of the guide member 22 along the longitudinal direction, and both sides of the partition portion 25 are shown in FIG.
As shown in FIG.
Is provided. The partition 25 has three fluid passage holes 2
Three fluid passage holes 26 ₁ , 26 ₂ and 26 ₃ are similarly formed corresponding to 3 ₁ , 23 ₂ and 23 ₃ .

At the portion of the guide member 22 located outside the pipe 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 is a perspective view showing the mounting state of the flow velocity sensor unit 27 with the guide member 22 and the flow velocity sensor unit 27 taken out. One unit member 27A forming the flow velocity sensor unit 27 is inserted into the unit insertion portion 22a of the guide member 22, and the other unit member 27B forming the flow velocity sensor unit 27 is inserted into the unit insertion portion 22b.

The flow rate sensor 29 _1, 29 _2, 29 _3, although not shown, the heating portion and having an upstream side and two temperature sensors disposed on the downstream side of the heating unit, detected by the two temperature sensors The flow rate corresponding to the flow velocity is calculated from the electric power supplied to the heat generating part necessary to keep the temperature difference constant, or the heat generating part is heated with a constant current or constant power.
The flow rate can be calculated from the difference in temperature detected by the two temperature sensors.

The distance from the front end of the large flow rate measuring flow path 13 to the flow velocity sensors 29 ₁ , 29 ₂ , 29 ₃ is, for example, 28 c.
m, the flow velocity sensor 29 from the front end of the small flow rate measurement flow path 14
Distance to _2, 29 ₃ is 15cm, for example.

_On the upstream side of the flow velocity sensors 29 ₁ , 29 ₂ , 29 _{3 in} the large flow rate measuring flow path 13 and on the upstream side of the flow velocity sensors 29 ₂ , 29 _{3 in} the small flow rate measuring flow path 14, respectively, As a rectifying member that regulates the flow of gas,
Wire meshes 31 and 32 of about 50 mesh are provided.

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, flow meters, the large flow velocity sensor 29 in the measurement flow path 13 _1, 29 _2, 29 ₃ of the average value of the flow velocity in the large flow rate measuring flow path 13 based on the output signals the mean flow velocity calculating unit 41 for calculating an average of calculating the average value of the flow velocity in the small flow rate measuring flow path 14 based on the output signals of the flow sensors 29 _2, 29 ₃ in the small flow rate measuring flow path 14 Based on the flow velocity calculation unit 42, a signal switching unit 43 that selects and outputs one of the output of the average flow velocity calculation unit 41 and the output of the average flow velocity calculation unit 42 according to the flow rate, and the output of this signal switching unit 43 In order to output the flow rate calculation unit 44 for calculating the flow rate and the integrated flow rate, the display unit 45 for displaying the integrated flow rate calculated by the flow rate calculation unit 44, and the flow rate and the integrated flow rate calculated by the flow rate calculation unit 44 to the outside. Outside of And an output terminal 46. The signal switching unit 43 outputs the output of the average flow velocity calculating unit 42 to the flow amount calculating unit 44 when the flow amount calculated by the flow amount calculating unit 44 is in a preset small flow amount region, and is calculated by the flow amount calculating unit 44. When the flow rate is within a preset large flow rate range, the output of the average flow velocity calculation section 41 is output to the flow rate calculation section 44. When the flow rate is within a preset small flow rate range, the flow rate calculation unit 44 multiplies the average value of the flow velocity output from the average flow velocity calculation unit 42 by the pipe shape factor corresponding to the small flow rate measurement flow passage 14. The flow rate is calculated, and when the flow rate is within a preset large flow rate range, the average value of the flow rates output from the average flow rate calculation unit 41 is multiplied by the pipe shape factor corresponding to the large flow rate measurement flow path 13 to determine the flow rate. Is calculated.

If the small flow rate region and the large flow rate region are partially overlapped and the flow rate increases, when the flow rate reaches the upper limit value of the overlapping region, the output of the average flow rate calculation unit 42 is changed to the average flow velocity calculation unit 41. When the flow rate decreases and the flow rate reaches the lower limit of the overlap area, the average flow velocity calculation unit 4
The flow rate may be calculated by switching the output of 1 to the output of the average flow velocity calculation unit 42. Average velocity calculator 41,
The signal switching unit 42, the signal switching unit 43, and the flow rate calculation unit 44 are configured by, for example, a microcomputer.

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

The gas introduced from the inlet portion 11 is first formed in the fluid passage holes 23 ₁ , 23 ₂ , 23 ₃ formed in the guide member 22 in the large flow rate measuring flow path 13 and the flow velocity sensor unit 27. Fluid passage holes 28 ₁ , 28
₂ , 28 ₃ and the fluid passage holes 26 ₁ , 26 ₂ , 26 ₃ formed in the partition 25. At that time, a flow rate sensor 29 _1, 29 _2, 29 ₃ the fluid passage holes 23 21 _to
A signal according to the flow velocity of the gas passing through 3 ₃ , 28 _{1 to} 28 ₃ and 26 _{1 to} 26 ₃ is output.

Next, the gas passes through the fluid passage holes 23 ₂ formed in the guide member 22 in the small flow rate measuring flow path 14,
23 ₃ , the fluid passage holes 28 ₂ and 28 ₃ formed in the flow velocity sensor unit 27, and the fluid passage holes 26 ₂ and 26 ₃ formed in the partition portion 25, and are discharged from the outlet portion 12. At that time, the flow velocity sensors 29 ₂ and 29 ₃ output signals according to the flow velocity of the gas passing through the fluid passage holes 23 ₂ , 23 ₃ , 28 ₂ , 28 ₃ , 26 ₂ , and 26 ₃ .

The average flow velocity calculation unit 41 calculates the average value of the flow velocity in the large flow rate measurement flow path 13 based on the output signals of the flow velocity sensors 29 ₁ , 29 ₂ , 29 _{3 in} the large flow rate measurement flow path 13. calculated, the average flow velocity calculating unit 42 calculates the average value of the flow velocity in the small flow rate measuring flow path 14 based on the output signals of the flow sensors 29 _2, 29 ₃ in the small flow rate measuring flow path 14. The signal switching unit 43 outputs the output of the average flow velocity calculation unit 42 when the flow rate calculated by the flow rate calculation unit 44 is in a preset small flow rate region.
4 and the flow rate calculated by the flow rate calculation unit 44 is in the preset large flow rate range, the average flow velocity calculation unit 4
The output of 1 is output to the flow rate calculation unit 44. Flow rate calculation unit 44
When the flow rate is in a preset small flow rate range, the flow rate and the integrated flow rate are calculated based on the average value of the flow rate output from the average flow rate calculation unit 42, and the flow rate is in the preset large flow rate range. At this time, the flow rate and the integrated flow rate are calculated based on the average value of the flow rates output from the average flow rate calculation unit 41. The integrated flow rate calculated by the flow rate calculation unit 44 is displayed on the display unit 45. The small flow rate region and the large flow rate region are partially overlapped, and in the overlapping region, the flow rate calculation unit 44 calculates the flow rate calculated based on the average value of the flow velocity output from the average flow velocity calculation unit 42 and the average flow velocity calculation unit 41. It is also possible to obtain an average value with the flow rate calculated based on the average value of the flow velocity that is the output of, and use this average value as the measured flow rate.

[First Embodiment] FIG. 5 shows flow velocity sensors 29 ₁ and 2 in the large flow rate measurement flow path 13 for each flow rate.
9 shows an example of each output value of 9 ₂ and 29 ₃ and an average value thereof, and FIG. 6 is an enlarged view of a portion indicated by reference numeral 51 in FIG. Figure 7 is a flow sensor 29 ₂ in the small flow rate measuring flow path 14 for each flow rate, 29
_It shows an example of each output value of ₃ and its average value,
FIG. 8 is an enlarged view of the portion indicated by reference numeral 52 in FIG. In these figures, the flow velocity sensor 2
9 _1, 29 _2, 29 _3, respectively upper sensor, center sensor, wrote the lower sensor. Air is used as the gas.

As shown in FIGS. 5 to 8, the flow velocity sensors 29 ₁ , 29 ₂ , 2 in the large flow rate measuring channel 13 are shown.
9 ₃ is a flow velocity sensor 29 in the small flow rate measurement flow path 14
₂ and 29 ₃ have a steeper slope and a higher sensitivity in the large flow rate region, and conversely, the flow velocity sensors 29 ₂ and 29 ₃ in the small flow rate measurement flow passage 14 are flow velocity in the large flow rate measurement flow passage 13. Compared with the sensors 29 ₁ , 29 ₂ , 29 ₃ , the inclination is steep and the sensitivity is high in the small flow rate region. Therefore, as in the present embodiment, in the small flow rate region, the flow rate is calculated based on the outputs of the flow velocity sensors 29 ₂ and 29 _{3 in} the small flow rate measurement flow path 14,
In a large flow rate range by calculating the flow rate based on the output of the flow sensor 29 _1, 29 _2, 29 ₃ in the large flow rate measuring flow path 13 can be measured accurately flow over a wide flow range.

Further, in the flowmeter according to the present embodiment, a plurality of flow velocity sensors are provided in the large flow rate measurement flow path 13 and the small flow rate measurement flow path 14, respectively, and the output signals of the plurality of flow rate sensors are provided. Since the average value of the flow velocity is calculated based on this, and the flow rate is calculated based on this average value of the flow velocity, even if the flow velocity distribution in the flow path changes depending on the magnitude of the flow amount, the output of one flow velocity sensor The flow rate can be measured more accurately than in the case where the flow rate is calculated based on.

Further, in the flowmeter according to the present embodiment, the flow velocity sensors 29 ₁ , 29 in the large flow rate measuring flow path 13 are provided.
_2, 29 ₃ of the upstream and the small flow rate measuring flow path flow rate sensor 29 ₂ within 14, 29 ₃ of the upstream side, since each is provided with a wire mesh 31, 32 as a rectifying member, it passes through the flow sensor The gas flow is regulated and the flow rate can be measured more accurately.

Further, the flowmeter according to the present embodiment can be made compact, and the pressure loss can be reduced as compared with the throttle type flowmeter.

[Second Embodiment] Next, the second embodiment of the present invention will be described.
The embodiment will be described.

In the first embodiment, a guide member is used in each of the large flow rate measurement flow path 13 and the small flow rate measurement flow path 14 to arrange a plurality of flow velocity sensors at the center of each flow path. However, in the present embodiment, as shown in FIGS. 9 and 10, a plurality of flow velocity sensors are installed on the wall surface of the flow path.

FIG. 9 shows a sectional structure of the flowmeter according to the second embodiment, and FIG. 10 shows a sectional structure taken along the line BB of FIG. This flowmeter has a pipe 5 having an inlet portion 51 for receiving gas and an outlet portion 52 for discharging gas.
0 is provided. This pipe 50 is used for the large flow rate measurement flow path 5.
3 and a small flow rate measurement flow path 54 that is provided in series on the downstream side of the large flow rate measurement flow path 53 and has a smaller cross-sectional area than the large flow rate measurement flow path 53. The diameter φ ₁ of the large flow rate measurement flow path 53 is, for example, 50 mm, and the small flow rate measurement flow path 14
The diameter φ ₂ is, for example, 26.6 mm.

On the wall surface of the large flow rate measuring channel 53, a plurality of, for example, four flow velocity sensors 55 _{1 to} 55 ₄ are arranged at equal intervals. On the other hand, in the small flow rate measuring flow path 54, a plurality of, for example, four flow velocity sensors 56 _{1 to} 56 are also provided on the wall surface.
₄ are evenly spaced. Here, a flow rate sensor 56 _{1-56 4} small flow rate measuring flow path 54 side, as viewed in the longitudinal direction of the pipe, a large flow rate measuring flow path 53 as shown in FIG. 10
It is installed shifted by a predetermined angle, for example, 45 degrees respectively with respect to a flow rate sensor 551 _to 554 ₄ side. Also,
These flow rate sensors 56 ₁ to 56 ₄ is large flow rate measuring flow path 5
It is arranged at a position immediately after the flow path reducing portion 50a in the boundary portion with 3, that is, in a position within a range of a distance D from the flow path reducing portion 50a which is ½ (13.3 mm) of the flow path diameter φ ₂ . .

[0048] together with its body portion flow sensor 551 _to 554 ₄ and a flow rate sensor 56 _{1-56 4} respectively are disposed in the sensor installation portion 57 provided on the wall surface of each flow path, each detector 59 also It is arranged so as to face the flow path through a measurement hole 58 provided on the wall surface. Flow sensor 55
_{1 to} 55 ₄ and the flow velocity sensors 56 _{1 to} 56 ₄ are mounted on the printed circuit board 60, respectively. These printed circuit boards 60 are connected to an electronic circuit section 61 having the same configuration as the circuit (FIG. 4) in the first embodiment. Incidentally, the flow velocity sensor 551 _to 554 ₄ and a flow rate sensor 56 _{1-56 4} has the same configuration as the flow sensor shown in the first embodiment, respectively.

On the upstream side of the large flow rate measuring flow path 53, a rectifying strainer 62 is provided as a rectifying member for regulating the flow of gas, which is composed of a large number of pipes. Before and after the rectifying strainer 62, wire meshes 63 and 64 of about 50 mesh for adjusting the flow of gas and removing dust in the gas are provided, respectively. The other configurations are similar to those of the first embodiment, and thus the description thereof is omitted.

FIG. 11 shows the flow velocity distribution of the gas in the large flow rate measuring channel 53. As is clear from this figure, since the flow velocity near the wall surface is slow, a larger flow rate can be measured with the same flow channel diameter than when a flow velocity sensor is installed at the center of the flow channel. On the other hand, FIG. 12 shows the flow velocity distribution of the gas in the small flow rate measurement flow path 54. As is apparent from this figure, the flow rate sensor 56 _1-56 the flow velocity distribution of the position immediately after the ₄ arranged flow channel reduction unit 50a has a small difference in the wall near the central portion, even near the wall surface flow rate is faster . Therefore, even if the flow velocity sensor is installed on the wall surface, it is possible to measure up to a small flow rate.

That is, in the flowmeter according to the second embodiment, the large flow rate measuring flow path 53 and the small flow rate measuring flow path 5 are provided.
By installing each flow velocity sensor on the wall surface in each of the four, it is possible to measure the flow rate in a wider range of a smaller flow rate and a larger flow rate as compared with the first embodiment. The small flow rate measuring flow path 54 side flow sensors 56 ₁ to 56 ₄ of, since it is placed shifted by 45 degrees respectively with respect to a flow rate sensor 551 _to 554 ₄ of the large flow rate measuring flow path 53 side ,
The flow velocity sensors 55 _{1 to} 55 ₄ and the flow velocity sensors 56 _{1 to} 56 ₄ do not overlap each other in the front and rear with respect to the flow direction of the gas. Therefore, since the flow velocity sensors 56 _{1 to} 56 ₄ on the small flow rate measurement flow path 54 side are not affected by the flow turbulence generated by the flow velocity sensors 55 _{1 to} 55 ₄ on the large flow rate measurement flow path 53 side, The flow rate can be measured.

Further, in the second embodiment, since the flow velocity sensors 55 _{1 to} 55 ₄ and the flow velocity sensors 56 _{1 to} 56 ₄ are installed on the wall surface, the guide member is inserted in the central portion of the flow path. Compared with the first embodiment, the turbulence of the flow in the central portion is small, and the flow rate can be measured more accurately. Further, since the need to provide a rectifying member in front of the small flow rate measuring flow path 54 side of the flow sensor 56 _{1-56 4} is eliminated, the configuration is simplified.

In this embodiment, the large flow rate measuring flow path 53 is provided.
Flow sensor 55 _to 554 ₄ and the small flow rate measuring flow path 5
In the overlapping flow rate range (for example, 150 to 300 liters / min) that can be measured by the flow velocity sensors 56 _{1 to} 564 of No. ₄ , the large flow rate measurement flow path 53 and the small flow rate measurement flow path 54
Two flow rates calculated on the basis of each output (average value of flow velocity) are averaged to obtain a measured flow rate. As a result, the average flow velocity value in each of the large flow rate measurement flow path 53 and the small flow rate measurement flow path 54 is independently used in the flow rate range (150 liters /
Flow rate below min, above 300 liter / min)
It is possible to reduce the amount of inconsistency in the measured flow rate value caused by switching between the two. In the overlapping flow rate region, the flow rate may be calculated by multiplying the average flow velocity values in the large flow rate measurement flow path 53 and the small flow rate measurement flow path 54 by a weighting coefficient as shown in FIG. .

[0054] Further, in the present embodiment, the small flow rate measuring in flow rate range for calculating the flow rate using the output of the flow sensor 551 _to 554 ₄ of the large flow rate measuring flow path 53 (300 L / min or higher) Flow rate sensors 56 _{1 to} 5 5
The electric power supply to each heat generating portion (heater) of 6 ₄ is cut off, and conversely, the flow velocity sensors 56 _{1 to} 56 ₄ of the small flow rate measuring flow path 54.
In the flow rate range (150 liters / min or less) in which the flow rate is calculated using the output of the above, the power supply to each heat generating portion (heater) of the flow velocity sensors 55 _{1 to} 55 ₄ of the large flow rate measuring flow path 53 is cut off. With the configuration, power consumption can be reduced.

[Second Embodiment] FIGS. 14 to 20 show an example of a flow rate measurement result for confirming the measurement accuracy of the flow meter according to the second embodiment. The experiment was performed by setting the ambient temperature to room temperature (22 to 24 ° C.) and flowing air as a fluid at a pressure of 4 kg / cm ² .

FIG. 14 shows a large flow rate measuring flow path (flow path diameter 50 m).
m) 53 and a small flow rate measuring flow path (flow path diameter 26.6 m)
m) 54 shows the flow rate characteristics (relationship between flow rate and output value (digital bit value)) for each of 54. Flow velocity sensors 55 _{1 to} 55 ₄ and flow velocity sensor 56 ₁
To 56 ₄ could be confirmed that the variation in output between the sensors is small for each. 15 and 16 show the relationship between the flow rate and the output value (current output of 4 to 20 mA). FIG. 15 shows the output characteristic in the flow rate range of 0 to 1200 (liter / min), and FIG. 16 shows 0. The output characteristics are shown in the flow rate range of up to 20 (liter / min). As is clear from these figures, it was confirmed that a linear output was obtained with respect to the flow rate up to the extremely low flow rate region.

17 to 19 show the relationship between the flow rate and the error of the output value (current output of 4 to 20 mA). FIG. 17 shows the error in the flow rate range of 0 to 1200 (liter / min). 18 is 0 to 100 (liter /
min) error in the flow rate range, 0 to 20 in FIG.
It shows the error characteristics in the flow rate range of (liter / min). In addition, in these figures, the measurement result of the first day and the measurement result of the second day are shown together, and the repeatability thereof is also shown. As is clear from these figures, the tendency of the error was the same for both days, and the unevenness of the error was also reproduced, confirming that the reproducibility was good. It is considered that the error includes an error of the measuring device. As a result of repeated measurement, low flow rate (20 liter /
The error is large below min).

FIG. 20 shows the relationship between the error represented by digital output and the flow rate before converting the output value into the current value of 4 to 20 mA for each of the large flow rate region and the small flow rate region. This digital output is 10 liters / mi
It can be confirmed that the error is small even near the low flow rate of n. Therefore, the error in the above low flow rate range is 4 to 20 m.
It can be considered that the current output of A is increased due to the drift due to the temperature characteristic.

As is clear from the above results, in the second embodiment, in the flow rate range of 600: 1 (the range of 2 to 1,200 liter / min in the above embodiment), the measurement error as the current output ±. It was found that a flowmeter within 5% can be realized.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of equivalents thereof. For example, in the first embodiment, the flow rate sensors provided in the large flow rate measurement flow path 13 and the small flow rate measurement flow path 14 are each 1
You can use each one. Further, the present invention also includes a device in which the rectifying members 31 and 32 are not provided. Further, the diameter of the inlet portion 11 may be equal to the diameter of the pipe 10 in the large flow rate measurement flow path 13 portion. In addition, as shown in FIG.
Alternatively, it may be detachable, or the members shown in FIG. 1 may be integrated. Further, the large flow rate measurement flow path 13 may be formed on the downstream side, and the small flow rate measurement flow path 14 may be formed on the upstream side.

Further, in any of the embodiments, the cross-sectional shape of the flow channel is not limited to a circular shape, but may be a semicircle, an ellipse, a square or the like. Further, the flow velocity sensor is not limited to the one having the heat generating portion and the two temperature sensors, and may be, for example, 1
The temperature of the heat generating part is calculated by calculating the flow velocity from the power supplied to the heat generating part required to keep the temperature (resistance) of the heat generating part constant, or by heating the heat generating part with a constant current or constant power. It is also possible to obtain the flow velocity from (resistance). Further, the present invention can be applied to a flow meter that measures the flow rate of liquid as well as gas.

[0062]

As described above, the first to fourteenth aspects of the invention can be realized.
According to the flowmeter described in any one of 1, the first flow velocity sensor outputs a signal corresponding to the flow velocity of the fluid passing through the first flow path for large flow rate measurement, and the second flow velocity sensor , A signal corresponding to the flow velocity of the fluid passing through the second flow passage for measuring a small flow rate having a smaller cross-sectional area than that of the first flow passage is output, and the flow rate calculating means outputs the first flow velocity according to the flow rate. Since the flow rate is calculated based on at least one of the output signal of the sensor and the output signal of the second flow velocity sensor,
There is an effect that the flow rate can be measured in a wide flow rate range.

Particularly, according to the flowmeters of claims 7 to 10, the plurality of flow velocity sensors are provided at predetermined intervals on the wall surface along the cross section in the direction orthogonal to the longitudinal direction of the pipes forming the flow paths. Since they are arranged, there is an effect that the flow rate can be accurately measured over a wider range.

[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.

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

5 is a characteristic diagram showing an example of each output value of a flow velocity sensor in a large flow rate measurement flow path in the flow meter shown in FIG. 1 and an average value thereof.

FIG. 6 is a characteristic diagram showing a part of FIG. 5 in an enlarged manner.

FIG. 7 is a characteristic diagram showing an example of each output value of the flow velocity sensor in the small flow rate measurement flow path in the flow meter shown in FIG. 1 and an average value thereof.

FIG. 8 is a characteristic diagram showing a part of FIG. 7 in an enlarged manner.

FIG. 9 is a cross-sectional view showing a configuration of a flowmeter according to a second embodiment of the present invention.

10 is a diagram showing a cross-sectional configuration taken along the line BB of FIG.

11 is a diagram showing a flow velocity distribution in a large flow rate measurement flow path of the flow meter of FIG. 9.

12 is a diagram showing a flow velocity distribution in a small flow rate measurement flow path of the flow meter of FIG.

FIG. 13 is a diagram for explaining a measuring method in an overlapping region of a large flow rate region and a small flow rate region.

FIG. 14 is a flow rate and an output value (digital bit value) for each of the large flow rate measurement flow path and the small flow rate measurement flow path.
It is a figure showing the relationship with.

FIG. 15 is a diagram showing a relationship between a flow rate and an output value (current output of 4 to 20 mA) in a flow rate range of 0 to 1200 (liter / min).

FIG. 16 is a diagram showing a relationship between a flow rate and an output value (current output of 4 to 20 mA) in a flow rate range of 0 to 20 (liter / min).

FIG. 17 is a diagram showing a relationship between a flow rate in a flow rate range of 0 to 1200 (liter / min) and an error of an output value (current output of 4 to 20 mA) including reproduction characteristics.

FIG. 18 is a diagram showing a relationship between a flow rate in a flow rate range of 0 to 100 (liter / min) and an error of an output value (current output of 4 to 20 mA) including reproduction characteristics.

FIG. 19 is a diagram showing a relationship between a flow rate and an error in a flow rate range of 0 to 20 (liter / min) including reproduction characteristics.

FIG. 20 is a diagram showing a relationship between a flow rate and an error of digital output.

FIG. 21 is a sectional view showing a configuration of a conventional flowmeter.

[Explanation of symbols]

10, 50 Piping 13, 53 Large flow rate measurement flow path 14, 54 Small flow rate measurement flow path 29 ₁ , 29 ₂ , 29 ₃ Flow rate sensor 55 _{1 to} 55 ₄ , 56 _{1 to} 56 ₄ Flow rate sensor 41, 42 Average flow rate Calculation unit 43 Signal switching unit 44 Flow rate calculation unit 45 Display unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumi Oni 9-10 Fujisawa City, Kanagawa Prefecture Misonodai 9-10 (72) Inventor Shigeru Hamada 3-9-1 Nakamagome, Ota-ku, Tokyo (72) Koji Aida 3-8-103 Fujimi, Tsurugashima City, Saitama Prefecture (72) Inventor Tadashi Hirano 2-9-5, Miyamaehira, Miyamae-ku, Kawasaki City, Kanagawa Prefecture (72) Hideo Sugimoto, 3-13-1, Imaizumi, Utsunomiya City, Tochigi Prefecture (72) Invention Hiroyuki Inagaki 5683-9 Ohba, Fujisawa-shi, Kanagawa Prefecture (72) Inventor Toru Matsumi 1-4-26 Matsunami, Chigasaki-shi, Kanagawa Prefecture (72) Inventor Nobuyoshi Shingyoji 2-757-2 (72) Zama, Kanagawa Prefecture Hiroshi Tahara 4-33-13 Maehara Nishi, Funabashi, Chiba Prefecture Palais d'Or Tsudanuma 106 (72) Inventor Yuji Morimoto 13-47-7 Kita 47 East Higashi-ku, Sapporo, Hokkaido Inventor Osamu Miura Hokkaido Ebetsu city Kamiebetsu Nishimachi 30-17

Claims (14)

[Claims] 1. A first flow path for measuring a large flow rate through which a fluid passes, and a small flow rate measurement section provided in series with the first flow path and having a cross-sectional area smaller than that of the first flow path. A second flow path, a first flow rate sensor that outputs a signal corresponding to the flow rate of the fluid passing through the first flow path, and a signal corresponding to the flow rate of the fluid passing through the second flow path. And a flow rate calculating means for calculating the flow rate based on at least one of the output signal of the first flow rate sensor and the output signal of the second flow rate sensor in accordance with the flow rate. A flowmeter characterized by 2. A plurality of the first flow velocity sensors are provided in the first flow passage, and an average value of the flow velocity in the first flow passage is calculated from output signals of the plurality of first flow velocity sensors. The flowmeter according to claim 1, further comprising a first average flow velocity calculating means in the flow path for outputting to the flow rate calculating means. 3. The flow meter according to claim 2, wherein each of the plurality of first flow velocity sensors is arranged at a central portion in the first flow path. 4. A guide member insertion portion provided so as to penetrate a wall surface along a longitudinal direction of a pipe forming the first flow path, and inserted into the pipe through the guide member insertion portion. A hollow guide member having a plurality of first fluid passage holes along the flow direction of the fluid, and a hollow guide member inserted into the guide member and corresponding to the plurality of first fluid passage holes of the guide member. And a flow velocity sensor unit having a plurality of second fluid passage holes, wherein the plurality of first flow velocity sensors are arranged so as to face the plurality of second fluid passage holes with respect to the flow velocity sensor unit, respectively. The flowmeter according to claim 3, characterized in that 5. A plurality of the second flow velocity sensors are provided in the second flow passage, and an average value of the flow velocity in the second flow passage is calculated from output signals of the plurality of second flow velocity sensors. The flowmeter according to claim 2, further comprising a second average flow velocity calculating means for outputting to the flow rate calculating means. 6. A guide member inserting portion provided so as to penetrate a wall surface along a longitudinal direction of a pipe forming the second flow path, and inserted into the pipe through the guide member inserting portion. At the same time, a hollow guide member having a plurality of first fluid passage holes along the fluid flow direction, and a hollow guide member inserted into the guide member and corresponding to the plurality of first fluid passage holes of the guide member. Flow velocity sensor unit having a plurality of second fluid passage holes, and the plurality of second flow velocity sensors are arranged so as to face each of the plurality of second fluid passage holes with respect to the flow velocity sensor unit. The flowmeter according to claim 5, characterized in that 7. The plurality of first flow velocity sensors are arranged at predetermined intervals on a wall surface along a cross section in a direction orthogonal to the longitudinal direction of the pipe forming the first flow path. The flowmeter according to claim 2. 8. The plurality of second flow velocity sensors are arranged at predetermined intervals on a wall surface along a cross section in a direction orthogonal to the longitudinal direction of the pipe forming the second flow path. The flowmeter according to claim 7, characterized in that. 9. The plurality of second flow velocity sensors are arranged in a state of being displaced from each other by a predetermined angle with respect to each of the first flow velocity sensors when viewed in a longitudinal direction of a pipe forming a second flow path. The flowmeter according to claim 8, wherein 10. The second flow path is arranged on the downstream side of the first flow path, and the plurality of second flow velocity sensors are respectively arranged at boundaries between the first flow path and the second flow path. The flowmeter according to claim 9, wherein the flowmeter is arranged within a range of a distance of ½ of the inner diameter of the second flow path from the position. 11. An overlapping flow rate region in which both the first flow velocity sensor and the second flow velocity sensor are measurable is provided, and in this overlapping flow rate region, the flow rate calculation means includes the first flow rate calculating unit.
Of the second average flow velocity value output from the second average flow velocity calculation unit and the second average flow velocity value calculated from the first average flow velocity value output from the second average flow velocity calculation unit. The flowmeter according to claim 5, wherein an average value with the flow rate is used as the measured flow rate. 12. In the flow rate range in which the flow rate is calculated using the output of one of the first flow rate sensor of the first flow path and the second flow rate sensor of the second flow path, The flowmeter according to claim 1, wherein power supply to the flow velocity sensor is cut off. 13. A flow passage is arranged in the first flow passage, upstream of the first flow velocity sensor, and in the second flow passage, upstream of the second flow velocity sensor. 7. The flowmeter according to claim 2, further comprising a rectifying member. 14. The flow control device according to claim 7, further comprising a rectifying member that is provided upstream of the first flow velocity sensor in the first flow path and regulates the flow of fluid.
The flowmeter according to any one of 0.