JP3373430B2 - Pipe flow meter - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vortex train generated by a vortex generator placed in a fluid flow, that is, a Karman vortex flowmeter for detecting a Karman vortex and measuring the flow rate. The present invention relates to an in-pipe flow rate measuring device for measuring.

[0002]

2. Description of the Related Art According to Japanese Patent Laid-Open No. 4-66817,
Karman vortex flow rate that enables flow rate measurement with a large rangeability by using a micro flow sensor (thermal flow velocity detection element; hereinafter, "micro flow sensor" and "thermal flow velocity detection element" are used as synonyms) Total is proposed.

The conventional Karman vortex flowmeter described above is shown in FIGS.
Explained by. In FIG. 7, reference numeral 101 denotes a pipe through which a fluid flows, and at the center of the flow of the pipe 101, for example, a triangular prism vortex generator 102 is arranged in the axial direction. The vortex generator 102 is provided with a bypass flow passage 103 as a communication hole in a direction perpendicular to the fluid flow direction F, and the fluid vibration 10 according to the vortex generation frequency is provided in the bypass flow passage.
5 occurs. Then, the microflow sensor 104 is arranged so that the vibration direction of this fluid and the detection direction of the sensor match.
Are arranged in the bypass channel 103.

This micro flow sensor 104 is shown in FIG.
As shown in FIG.
12 and temperature sensors 113 and 114, which are made of a metal thin film having a very small heat capacity, are integrated on the both sides thereof in the order of microns. The temperature sensors 113 and 114 detect the temperature change on both sides of the heater 112 to detect the fluid vibration 105. A detection signal is obtained.

At this time, as a detection circuit, a circuit for heating the heater 112 of the microflow sensor 104 to a constant temperature by supplying a predetermined power from the driving power source V _H , and temperature sensors 113 on both sides of the heater 112, A circuit for applying a constant voltage from the drive power source V _B is prepared for 114, and is configured to have a function of detecting and amplifying the voltage V of the vibration waveform generated at the midpoint of both temperature sensors 113, 114. Then, the detection voltage V obtained by this detection circuit is input to an arithmetic circuit via a comparator, calculated as the frequency per unit time by this arithmetic circuit, and then multiplied by the Strouhal number measured in advance. Then, the flow rate can be measured from the calculation result.

[0006]

In the above-mentioned prior art example, in principle, it is sufficiently expected to enable flow rate measurement with a large rangeability, but in terms of safety, measurement accuracy, manufacturing / assembly, It has not been sufficiently disclosed about problems such as easiness in actually mounting the Karman vortex flowmeter using the microflow sensor on the pipe.

For example, as described above, the microflow sensor 104 is provided with the heater 112, and has a structure in which an extremely small amount of heat is generated by external power supply. Therefore, when the fluid to be measured is a flammable fluid, it may not be possible to use it in a normal environment, but some adverse conditions may overlap and the microflow sensor may become an ignition source. Need to be implemented.

In order to commercialize the device, it is necessary to solve the problem that the flow of the fluid around the microflow sensor is disturbed due to the shape of the vortex generator, and highly accurate measurement cannot be performed. There is a need to solve problems such as cost reduction, easy assembling to a pipe, and easy maintenance / inspection after mounting on a pipe.

The present invention has been proposed in order to deal with the above situation, and solves the above problems and mounts a Karman vortex flowmeter using a microflow sensor on a pipe. It is an object of the present invention to provide an in-pipe flow rate measuring device that enables the above.

[0010]

In order to achieve the above object, the in-pipe flow rate measuring device according to the present invention firstly provides a vortex generator with a bypass flow passage which is orthogonal to the advancing direction of the fluid, and in the middle of the flow passage. In a pipe flow rate measuring device in which a Karman vortex flowmeter equipped with a thermal type flow velocity detecting element is installed in a pipe, a depth dimension and a gap size satisfying the explosion proof structure standard provided on both sides of the thermal type flow velocity detecting element in the bypass flow path are set. The safety gap is equipped with a pipe in which pipes that form multiple pores are densely arranged.
It is characterized by being a rame arrester .

In the above-mentioned pipe flow rate measuring device,
Cut off a part of the cylindrical material to form the vortex generator, and measure
Form a hole in the tube through which the constant fluid flows and insert the columnar material through the hole.
Insert the vortex generator into the tube and place it in the cylinder.
Form a pair of locking grooves on the part of the material protruding from the hole
And then fit a pair of fixing plates into the locking groove,
Is detachably fixed to the outer circumference of the pipe.
It

Further , assuming the above-mentioned pipe flow rate measuring device,
The thermal type flow velocity detecting element at the tip of the insert,
Insert the insert formed in the longitudinal direction inside the vortex generator
Insert it into the hole to connect the thermal type flow detection element to the bypass flow
It is characterized by facing the road.

[0013]

[0014]

The above-mentioned pipe flow rate measuring device is an invention which solves the common problem that the Karman vortex flowmeter using a microflow sensor (thermal flow rate detecting element) can be mounted on a pipe. The operation of each invention will be described below.

According to the first aspect of the present invention, when a micro flow sensor is used in the Karman vortex flowmeter, the flow rate can be measured by detecting the frequency of the alternating flow instead of detecting the flow velocity of the alternating flow. Even if a micro flow sensor becomes an ignition source when it is used for measuring the flow rate of a flammable fluid, it is proposed with a focus on ensuring safety by preventing the flame from spreading outside the measurement device. It is a thing.

According to this, by providing the safety clearance having the depth dimension and the clearance dimension satisfying the explosion proof structure standard on both sides of the thermal type flow velocity detecting element in the bypass flow path,
Even if the micro flow sensor acts as an ignition source in the bypass flow path and a flame is generated, the flame disappears while propagating through the safety gap described above, and the flame is not emitted to the outside of the measuring device. Can be secured. Since the micro flow sensor has high sensitivity, even if such a safety gap is provided in the bypass flow passage, the superiority of rangeability does not fluctuate as compared with the conventional Karman vortex flowmeter.

Further, in addition to the effects described above, a plurality of pores
Since the measured fluid in the bypass channel is rectified by the safety gap formed by the flame arrester in which the formed pipes are densely arranged , the flow rate measurement using the microflow sensor can be performed with higher accuracy.

In the second aspect of the invention, in addition to the above-mentioned action, the manufacture of the vortex generator or the mounting on the pipe is considered.
According to this, in addition to the above-mentioned action, the vortex generator can be formed only by notching the cylindrical member, which facilitates the processing and reduces the manufacturing cost, and the vortex generator can be easily assembled to the pipe. Further, since the fixing plate is detachably provided, the vortex generator can be easily attached and detached, and maintenance and inspection can be easily performed.

A third aspect of the present invention relates to the attachment of the microflow sensor to the vortex generator. According to this, in addition to the above-described action, the microflow sensor in the vortex generator is liable to be broken when a mechanical external force is applied. The bypass flow path can be easily assembled, the efficiency of assembling the flow rate measuring device is improved, and the micro flow sensor can be easily replaced in the case of failure.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a partial cross-sectional view from the front of an in-pipe flow rate measuring device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 3 is a cross-sectional view taken along the line BB in FIG. ing.

In FIGS. 1 and 3, 1 is a fluid pipe, 2 is a vortex generator disposed in the fluid pipe 1, and 3 is a bypass formed in the vortex generator 2 in a direction orthogonal to the traveling direction of the fluid. aisle,
Reference numeral 4 is a microflow sensor disposed in the middle of the bypass passage 3. The vortex generator 2 is formed by cutting out a part of the columnar member 21. The columnar member 21 is inserted into the hole 1A formed in the fluid pipe 1, is erected perpendicularly to the pipe axis of the fluid pipe 1, and the vortex generator 2 is arranged in the fluid pipe line 11. The fluid pipe 1 may have a structure in which mounting flanges 12 are mounted on both sides so that the predetermined length section in which the vortex generator 2 is disposed can be independently separated, or the fluid pipe 1 can be directly swirled to the fluid pipe 1 to be measured. The generator 2 may be incorporated. The columnar member 21 inserted into the hole 1A formed in the fluid pipe 1 is fixed to the outer periphery of the fluid pipe 1 by the bolt 14 via the fixing plate 13. This makes it possible to mount the optimum sensor in the flow direction.

As shown in FIGS. 1 and 2, flame arresters 5 are provided on both sides of the microflow sensor 4 in the bypass passage 3 formed in the vortex generator 2. The flame arrester 5 forms a safety gap having a depth dimension and a gap dimension that satisfy the explosion proof structural standard, and thereby a plurality of pores are formed at both ends of the bypass flow passage 3.

An example of the structure of the flame arrester 5 is shown in FIG. This has a structure in which an inner pipe 52 for forming a plurality of fine holes is densely arranged in an outer pipe 51 inscribed in the bypass flow path 3. The material of the outer pipe 51 and the inner pipe 52 is a metal pipe, and may be carbon steel for machine structure plated with nickel, stainless steel, copper, brass, or the like. As an example of dimensions, the depth of the inner and outer pipes is 6
mm, outer diameter of outer pipe 51 is 4 mm, wall thickness is 0.3 mm
, The outer diameter of the inner pipe 52 is 0.46 mm, the inner diameter is 0.25
mm.

The structure of the columnar member 21 above the bypass passage 3 will be described with reference to FIGS. Column material 21
An O-ring 22 is provided on the outer periphery of the columnar member 21. When the columnar member 21 is inserted into the hole 1A of the fluid pipe 1 and the vortex generator 2 is arranged in the fluid conduit 11, the O-ring 22 closes the hole 1A. It is hermetically sealed. Further, an insertion hole 21A facing the bypass passage 3 from the upper end is formed inside the columnar member 21,
The insert body 6 is mounted in the insert hole 21A so as to be freely inserted and removed. A can package 8 on which the microflow sensor 4 is mounted is attached to the tip of the insert 6 by a mounting member 7. A cable for guiding the signal of the microflow sensor 4 is arranged in the insert body 6, but the cable is not shown in FIGS. 1 and 3. Column material 21
A terminal box 23 is attached to the upper end of the terminal box 23, and a processing circuit (not shown) for processing a signal from the microflow sensor 4 is incorporated in the terminal box 23.

The structure around the insert 6 will be described in more detail with reference to FIG. The sensor chip of the microflow sensor 4 is mounted on the can package 8, and the conducting wire 81 projects from the back surface of the can package 8. This conductor wire 81 is a flat cable 61 arranged in the insert body 6.
Is detachably connected to a connector 62 provided at the end of the. Then, the can package 8 connected to the connector 62 is attached to the insert body 6 by the attaching member 7 with the microflow sensor 4 exposed at the tip.

The mounting member 7 has a detachable mounting structure such as screw connection, fitting, bayonet connection, etc.
If a problem occurs in the microflow sensor 4, the mounting member 7 is removed from the insert body 6, the can package 8 is removed from the connector 62, and the microflow sensor 4 can be easily replaced. It can be carried out.

The insert 6, the mounting member 7, and the can package 8 can be inserted into the insertion hole 1A of the columnar member 21 as an integral member. Therefore, the device can be easily assembled, and the microflow sensor 4 is exposed to the bypass flow passage 3 of the vortex generator 2 only by inserting the positioning portion 6A at the upper end of the insert 6 into the upper end of the columnar member 21. be able to.

FIG. 6 shows an example of the structure for mounting the in-pipe flow rate measuring device on a pipe. The same parts as those described above are designated by the same reference numerals and the description thereof is partially omitted. A flat portion 1B is formed in the upper portion of the fluid pipe 1, a hole 1A for inserting the columnar member 21 is provided in the center thereof, and a bolt hole 1C is formed in the flat portion 1B. A pair of locking grooves 21A is formed in a portion of the columnar member 21 protruding from the hole 1A. And the columnar material 21
Is inserted into the hole 1A of the fluid pipe 1, and the locking groove 2 of the columnar member 21 is inserted.
Fit the locking portions 13B of the pair of fixing plates 13 into 1A,
By inserting the bolt 14 into the mounting hole 13A of the fixing plate 13 and screwing it into the bolt hole 1C, the columnar member 21 is detachably fixed to the outer circumference of the fluid pipe 1.

The in-pipe flow rate measuring device having the above structure operates as follows.

The vortex generator 2 is provided with flame arresters 5 on both sides of the micro flow sensor 4 in the bypass flow path 3 which is orthogonal to the direction of fluid flow and which forms a safety clearance having a depth dimension and a clearance dimension satisfying the explosion proof structure standard. As a result, even if the micro flow sensor 4 serves as an ignition source and a flame is generated in the bypass flow passage 3 provided in the vortex generator 2, the flame disappears while propagating through the safety gap, No flame is generated in the fluid conduit 11 outside the measuring device, and safety can be ensured. Since the sensitivity of the micro flow sensor 4 is high, even if such a safety gap is provided in the bypass flow path 3, the superiority of rangeability does not fluctuate as compared with the conventional Karman vortex flowmeter.

Here, the structure of the flame arrester 5 is not limited to the structure shown in FIG. The entire flame arrester 5 may be formed of a porous sintered metal to form a safety gap inside the sintered metal, or may be a stack of parallel flat plates having a safety gap satisfying the quenching distance. . In short, it suffices that the microflow sensor 4 be able to detect the frequency of the alternating flow and form a gap having a depth dimension and a gap dimension satisfying the explosion proof structure standard.

Another effect of providing the flame arrester 5 in the bypass flow passage 3 is a rectifying function in the bypass flow passage. By disposing the flame arrester 5 having the safety gap composed of a plurality of pores as shown in FIG. 4 at both ends of the bypass flow passage, the fluid to be measured in the bypass flow passage is rectified. The flow rate measurement using can be performed with higher accuracy.

Regarding the production of the vortex generator 2, the cylindrical member 21
By forming a vortex generator 2 by cutting out a part of
It is easy to process and the manufacturing cost can be reduced.

Regarding the assembly of the measuring device and the mounting on the fluid pipe 1, a structure in which a hole 1A is formed in the fluid pipe 1 and a columnar member 21 is inserted from the hole 1A to arrange the vortex generator 2 in the pipe. ,
At that time, a structure in which the hole 1A is hermetically sealed by the O-ring 22 provided in the columnar material 21, a pair of locking grooves 21A is formed at the protruding portion of the columnar material 21 from the hole 1A, and the locking groove 21A is formed in the locking groove 21A. The structure has a structure in which a pair of fixing plates 13 are fitted together and the fixing plates 13 are detachably fixed to the outer periphery of the fluid pipe 1, and the vortex generator 2 can be easily assembled to the fluid pipe 1. The vortex generator 2 can be easily attached and detached, and maintenance and inspection can be easily performed.

Further, with respect to the attachment of the microflow sensor 4 to the vortex generator 2, a structure in which the microflow sensor 4 is attached to the tip of the insert 6 so as to be easily replaceable,
Insert the insert body 6 to which the microflow sensor 4 is attached into the insert hole 21A formed in the longitudinal direction of the cylindrical member 21,
The micro flow sensor 4 is provided with a structure that faces the bypass flow passage 3. According to this structure, the micro flow sensor 4 that is easily broken when a mechanical external force is applied can be easily attached to the bypass flow passage 3 in the vortex generator. As a result, the assembly work efficiency of the flow rate measuring device is improved, and when a defect occurs in the microflow sensor 4, it can be easily replaced.

[0037]

Since the in-pipe flow rate measuring device of the present invention is constructed as described above, it is possible to measure the flow rate with a large rangeability, and in consideration of safety, measurement accuracy, and ease of manufacturing / assembling. In the above, the Karman vortex flowmeter using the microflow sensor can be mounted on a pipe.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view from the front of a pipe flow rate measuring device according to an embodiment of the present invention.

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

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is an explanatory diagram showing a structure of a flame arrester according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a part of a pipe flow rate measuring device according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing mounting of a pipe flow rate measuring device according to an embodiment of the present invention on a pipe.

FIG. 7 is an explanatory diagram showing a conventional Karman vortex flowmeter.

FIG. 8 is an explanatory diagram of a microflow sensor used in a conventional Karman vortex flowmeter.

[Explanation of symbols] 1 fluid pipe 11 fluid lines 12 mounting flange 2 Vortex generator 21 Cylindrical material 22 O-ring 23 terminal box 3 bypass channels 4 Micro flow sensor 5 flame arresters 6 inserts 7 Mounting member 8 can packages

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masaki Seo 1-12-2 Kawana, Fujisawa-shi, Kanagawa Yamatake Honeywell Co., Ltd. Fujisawa Plant (72) Inventor Hiroyuki Inagaki 1-2-2 Kawana, Fujisawa, Kanagawa No. Yamatake Honeywell Co., Ltd. Fujisawa Plant (72) Inventor Junichi Iseya 1-21-2 Kawana, Fujisawa-shi, Kanagawa Yamatake Honeywell Co., Ltd. Fujisawa Plant (56) Reference JP-A-4-66817 (JP, A) ) JP-A-7-120284 (JP, A) JP-A-1-250726 (JP, A) JP-A-56-57912 (JP, A) Actually developed 4-51621 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (3)

(57) [Claims] 1. A pipe flow rate measuring device in which a Karman vortex flowmeter, in which a bypass flow passage orthogonal to a traveling direction of a fluid is provided in a vortex generator, and a thermal type flow velocity detecting element is provided in the flow passage, is mounted in the pipe. , Installed on both sides of the thermal flow velocity sensor in the bypass flow path.
Pipes that form multiple pores are densely arranged with safety clearances that have depth dimensions and clearance dimensions that meet the explosion-proof structural standards.
An in-pipe flow rate measuring device characterized by being a flame arrester installed . 2. A vortex generator in which a part of a cylindrical member is cut out.
To form a hole in the tube through which the fluid to be measured flows, and
When the columnar material is inserted and the vortex generator is placed inside the pipe,
Both have a pair of protrusions on the columnar member.
To form a locking groove, and fit a pair of fixing plates into the locking groove.
The fixing plate is detachably fixed to the outer circumference of the pipe.
The pipe flow rate measuring device according to claim 1, wherein: 3. The thermal type flow rate detecting element, wherein the thermal type flow velocity detecting element is arranged at a tip of the inserting body, and the inserting body is inserted into an inserting hole formed in a longitudinal direction inside the vortex generator. the is characterized in that to face to the bypass passage according to claim 1 or
Pipe flow measurement apparatus according to 2.