JP4672415B2 - High temperature fluid flow meter - Google Patents

Description

  The present invention relates to a flow meter for high-temperature fluid that detects a high-temperature fluid to be measured flowing inside a measurement tube with a sensor and guides an electrical signal corresponding to the flow rate output from the sensor to a circuit unit by a lead wire.

  A flowmeter that introduces a high-temperature fluid into the measuring tube, converts the flow rate into an electrical signal by various sensors, processes the electrical signal in the circuit unit, and measures the flow rate. If the heat is transmitted to the circuit unit by heat conduction or radiation / convection and the circuit board or the like is heated, there may be a malfunction such as malfunction in the processing of the electric signal. For this reason, it is necessary to interrupt the heat transfer to the circuit unit.

In the technique described in Patent Document 1, a lead wire for sending an electric signal from a sensor to a circuit board separated from a measurement tube is housed in a conduit of the metal tube, and the metal tube is provided by a radiating fin provided on the outer surface of the metal tube. The heat conduction is suppressed. In addition, an insulating plate is placed in the pipe of the metal tube to block heat radiation and convection to the circuit unit storage case inside the metal tube and protect the circuit board stored in the circuit unit storage case from heat. ing.
Japanese Utility Model Publication No. 60-3426

  However, in the method of suppressing the heat conduction to the circuit part by the heat radiation by the heat radiation fin, the thermal energy of the fluid to be measured is taken away by the heat radiation, which is not desirable in terms of energy efficiency. In addition, a thick heat insulating material may be wound around the measurement tube to suppress the heat dissipation of the fluid to be measured. However, sufficient heat dissipation by the heat radiating fins is not possible in the part where the metal tube is covered with the heat insulating material. It becomes difficult to sufficiently suppress the heat transfer to the circuit portion due to the heat conduction of the metal tube. As a result, the temperature in the circuit unit storage case becomes very high with respect to the ambient temperature, and the temperature of the circuit board exceeds the allowable range.

  It is an object of the present invention to provide a high-temperature fluid flow meter that can block heat transfer from a high-temperature measurement tube, sensor, etc. to a circuit unit, and that dissipates heat energy from a fluid to be measured. Yes.

The flow meter for high-temperature fluid of the present invention detects a high-temperature fluid to be measured flowing inside a measurement tube with a sensor, and guides an electric signal corresponding to the flow rate output from the sensor to a circuit unit through a conductor. A total of
A metal pipe and a resin pipe that lead the lead wire through the pipe to the circuit unit;
Connecting one end of the metal tube to the sensor, connecting a metal flange formed at the other end of the metal tube and a resin flange formed at one end of the resin tube;
It is arranged in a pipe line from at least a part of the pipe line of the metal pipe to the whole pipe line of the resin pipe, and the conductive wire is housed in a metal shield pipe that shields radio noise from the outside to the electrical signal, The conducting wire led to the end of the resin pipe is connected to the circuit unit.

The flow meter for high-temperature fluid of the present invention detects a high-temperature fluid to be measured flowing inside a measurement tube with a sensor, and guides an electric signal corresponding to the flow rate output from the sensor to a circuit unit through a conductor. A total of
A metal pipe and a resin pipe that lead the lead wire through the pipe line to the circuit portion are provided, and a metal thin film is formed on the pipe outer surface and / or the pipe inner surface of the resin pipe,
Connecting one end of the metal tube to the sensor, connecting a metal flange formed at the other end of the metal tube and a resin flange formed at one end of the resin tube;
The conducting wire is passed through the pipes of the metal tube and the resin tube, and the conducting wire led to the end of the resin tube is connected to the circuit unit.

  In the above invention, the conducting wire is housed in a pipe line that connects the metal pipe arranged on the measurement pipe side and the resin pipe arranged on the circuit part side with a flange, thereby blocking heat transfer to the circuit part. Yes. First, by connecting a heat-resistant metal tube to the sensor, heat resistance at the position near the measurement tube that becomes high temperature (for example, may reach about 200 ° C.) due to heat from the fluid to be measured is secured. is doing. The thickness of the metal tube is formed as thin as possible within the range allowed by other conditions such as strength. Thereby, the heat conduction to the circuit part side by the metal tube is suppressed.

  In order to suppress the dissipation of thermal energy from the fluid to be measured, when a heat insulating material is wound around the measuring tube, a metal tube is arranged from the inside of the heat insulating material that is at a high temperature to the outside of the heat insulating material. Expose the metal flange on the outside.

  Secondly, since the resin tube is connected to the metal tube at a position away from the high temperature portion in the vicinity of the measurement tube, the circuit is formed by a resin material having a thermal conductivity much smaller than that of the metal. The heat conduction to the part side is further suppressed.

  Thirdly, by connecting the metal pipe and the resin pipe with a flange, radiation and convection from the high-temperature measurement pipe (or the heat insulating material wound around the measurement pipe) toward the case housing the circuit section are caused by the flange. Shielded. A metal flange part also provides the effect | action which thermally radiates radiant heat. In particular, when a heat insulating material is wound around a measurement tube, radiation and convection occur in the gap between the metal tube and the heat insulating material. Both the hot air flow and the radiation flowing from the gap to the circuit side are flanged. The heat is diffused in a direction away from the case housing the circuit portion.

  With the above operation, the temperature inside the case that houses the circuit portion can be made to be approximately the same as the ambient temperature. As described above, in the present invention, heat transfer to the circuit portion is not suppressed by heat radiation, but heat transfer is suppressed by connecting a thin metal tube and a resin tube to reduce heat conduction. The heat energy of the fluid to be measured is not deprived more than necessary.

  Preferably, a heat insulating wall projecting inward from the inner peripheral surface of the pipe line is provided at a connecting portion between the metal tube and the resin tube or at a position closer to the resin tube than that. This heat insulating wall is constituted by, for example, a metal plate-like member fixed between a metal tube and a resin tube, or a resin wall formed integrally with the resin tube and projecting inward from the inner peripheral surface of the resin tube. can do. By this heat insulating wall, heat radiation and convection to the circuit part side inside the metal tube can be sufficiently shielded.

  Further, in one aspect of the present invention, since the conductive wire is housed in the metal shield tube, radio noise from the outside that enters the pipeline from the resin tube is shielded by the metal shield tube, and thereby the circuit portion from the sensor through the conductive wire. A weak electrical signal sent to the pipe is protected (thus, it is necessary to arrange a metal shield pipe over the entire pipe of the resin pipe. However, if the metal pipe sufficiently shields electromagnetic waves, the pipe of the metal pipe is not necessarily used. There is no need to dispose the metal shield tube over the entire path, in which case the metal shield tube may be disposed in the region from at least part of the conduit of the metal tube to the entire conduit of the resin tube). Since the metal shield tube is very thin, the heat conduction by the metal shield tube does not affect the circuit portion.

Further, in another aspect of the present invention, since the metal surface such as metal plating is applied to the tube surface of the resin tube, the entire pipeline formed by connecting the metal tube and the resin tube is protected from external radio noise. Shielded. Therefore, it is not necessary to use the above-mentioned metal shield tube, and the conducting wire can be accommodated in the pipeline as it is and led from the sensor to the circuit portion.

  According to the high-temperature fluid flow meter of the present invention, heat transfer from a high-temperature measurement tube or sensor to the circuit unit can be interrupted, and furthermore, heat energy is less dissipated from the fluid to be measured.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a flow meter for high-temperature fluid according to an embodiment of the present invention (a heat insulating material is omitted), and FIG. 2 is a view of the flow meter for high-temperature fluid in FIG. FIG. 3 is an enlarged cross-sectional view of the periphery of the connection portion between the measurement tube and the sensor.

  The flow meter for high-temperature fluid of this embodiment generates Karman vortices by a vortex generator provided in the flow path of the measurement tube, and detects the alternating pressure change of the Karman vortex as an alternating stress by a sensor to detect the fluid to be measured. It is a vortex flowmeter that measures the flow rate. The vortex flowmeter 1 is for measuring a flow rate of a high-temperature fluid to be measured flowing from a pipe into the measuring pipe 2 by connecting a measuring pipe 2 between pipe flanges (not shown).

  The measuring tube 2 is formed by precision casting such as the lost wax method (investment cast method). When using the lost wax method, first make a model of the measuring tube 2 and sensor unit 3 using a heat-soluble material such as beeswax or pine resin, and then coat this model with a refractory material such as silica sand or zirconia powder. To do. Thereafter, the model covered with the refractory material is heated to elute the heat-soluble model, and cast metal such as stainless steel is poured into the model part that has become a cavity and solidified. Then, the refractory material is removed, and surface treatment is performed by sandblasting or the like so that the surface of the finally cast measurement tube 2 becomes a smooth surface.

  A vortex generator 3c is arranged in the pipeline 2a of the cylindrical measurement tube 2 perpendicularly to the pipeline 2a. A sensor unit 3 integrated with the vortex generator 3c is disposed on the proximal end side of the vortex generator 3c. A bimorph sensor (not shown) is sealed with glass inside the sensor unit 3. A conducting wire 31 is electrically connected to the bimorph type sensor, and the connecting portion 3a on the side from which the conducting wire 31 is drawn is sealed with a sealing material such as silicon. As shown in FIG. 3, the sensor unit 3 is fixed to a mounting surface of the measurement tube 2 with a high-temperature fluid sealing packing 5 with a screw (not shown), whereby the vortex generator 3 c is fixed to the measurement tube 2. Is fixed to the cantilever. As the packing 5 for high temperature fluid sealing, for example, a material mainly composed of expanded graphite having a small expansion coefficient with respect to a high temperature may be used.

  As the fluid to be measured flows through the pipe line 2a, the vortex generator 3c generates a Karman vortex. The alternating stress change due to the Karman vortex is detected by acting on a bimorph type sensor housed in the sensor unit 3 from a pressure guide port (not shown) provided in the vortex generator 3c and converted into an electric signal. The electrical signal from the sensor unit 3 is transmitted to the circuit board (circuit unit 22) stored in the circuit unit storage case 21 through the conductive wire 31 connected to the connection unit 3a, and electrical processing such as amplification and calculation is performed. Done.

  As shown in FIG. 3, the sensor side flange portion 11c of the metal tube 11 is fixed to the outer fixing surface of the sensor fixing flange 3b of the sensor portion 3 with a high temperature fluid seal packing (not shown) interposed therebetween. Thus, the metal tube 11 is connected to the sensor unit 3. The conducting wire 31 is guided to the circuit unit 22 through the inside of the metal tube 11 while being housed in the metal shield tube 32.

  The metal shield tube 32 is configured such that the metal shield tube 32 is passed through the through hole of the metal plate 33 sandwiched between the wave washer 35 and the retaining ring 34 with respect to the circuit portion storage case 21 subjected to electromagnetic shielding treatment. It is fixed to the circuit unit storage case 21.

By fixing the metal shield tube 32 in this manner, the electromagnetic wave to the circuit portion of the circuit portion storage case 21 is shielded through the resin tube 12.
As shown in FIG. 2, a mineral fiber-based heat insulating material 4 such as rock wool heat insulating material is provided on the outer periphery of the measuring tube 2 in order to suppress the dissipation of heat energy from the high temperature fluid to be measured flowing through the pipe 2 a. Is wound. The long-necked metal tube 11 has a sensor-side region enclosed in the heat insulating material 4 and a metal flange portion 11 a exposed to the outside of the heat insulating material 5.

  The pipe portion 11b of the metal pipe 11 in FIG. 1 is made as thin as possible within the range allowed by other conditions such as strength. Thereby, the heat conduction from the pipe part 11b heated by the sensor part 3 and the heat insulating material 4 (FIG. 2) to the circuit part 22 side (heat conduction to the metal flange part 11a) is suppressed as much as possible. At the same time, the dissipation of the thermal energy of the fluid to be measured from the metal tube 11 is also suppressed.

  The metal flange portion 11a is fixed with screws 14 with the resin flange portion 12a of the resin tube 12 and the sealing material 13 interposed therebetween, whereby the metal tube 11 and the resin tube 12 are connected to each other. The conducting wire 31 accommodated in the metal shield tube 32 is guided to the circuit unit 22 through the metal tube 11 and the resin tube 12. As the material of the resin tube 12, a material having high heat resistance and low thermal conductivity such as PPS (polyphenylene sulfide) resin is preferably used. The end of the resin pipe 12 opposite to the resin flange portion 12a is connected to a resin circuit portion storage case 21. In this embodiment, in order to be able to adjust the arrangement of the circuit unit storage case 21, the circuit unit storage case 21 is rotatably connected to the resin tube 12 with the resin tube 12 as a rotation axis.

  Even if the tube portion 11b of the metal tube 11 is thinned, there is a certain limit to the suppression of heat conduction, but a tube constituted by connecting a resin tube 12 having a low thermal conductivity to the metal tube 11 By conducting the conductive wire 31 to the circuit unit storage case 21 by the path, heat conduction to the circuit unit storage case 21 is significantly suppressed.

  In addition, heat radiation and convection are generated in the gap between the heat insulating material 4 and the metal tube 11 shown in FIG. 2, and the heat is transferred from the gap 4 a to the outside of the heat insulating material 4 in the direction of the circuit unit storage case 21. Although an air flow occurs, the hot air flow and radiation are shielded by the flange by connecting the metal tube 11 and the resin tube 12 with flanges (the metal flange portion 11a and the resin flange portion 12a), and the circuit portion is accommodated. It diffuses away from the case 21. Furthermore, the metal flange portion 11a also provides an action of radiating heat due to the hot air flow and radiation.

  In the present embodiment, there are few portions where the metal tube 11 is exposed to the outside from the heat insulating material 4, and further, the outer side of the metal flange portion 11a (the circuit portion storage case 21 side) is covered with the resin flange portion 12a. The finger is difficult to touch the high temperature metal tube 11, and the handling is safe.

  As described above, in the present embodiment, since the thin metal tube 11 and the resin tube 12 are connected to suppress heat conduction to suppress heat transfer to the circuit unit storage case 21, It does not take away the heat energy of the fluid more than necessary. For example, when the fluid to be measured is a vapor fluid, deterioration in dryness can be suppressed.

Furthermore, since convection and radiation from the heat insulating material 4 side toward the circuit part storage case 21 are shielded by the metal flange part 11a and the resin flange part 12a, heat transfer to the circuit part storage case 21 is further suppressed. As a result, the internal temperature of the circuit unit storage case 21 can be set to the same level as the external ambient temperature, and malfunction caused by the heat generation of the circuit unit 22 stored in the circuit unit storage case 21 can be prevented.

  In the present embodiment, a metal fixing plate 15 is sandwiched and fixed between the metal flange portion 11a and the resin flange portion 12a. The fixing plate 15 extends perpendicularly to the pipe line from between the metal pipe 11 and the resin pipe 12 and has a through hole substantially equal to the diameter of the metal shield pipe 32 at the center. ing. The metal shield tube 32 is passed through the through hole, and the metal shield tube 32 is fixed by the fixing plate 15 and a pair of nuts 16 provided on the front and back surfaces thereof. The fixing plate 15 also functions as a heat insulating wall that shields radiation and convection to the circuit portion 22 side inside the metal tube 11.

  Since the resin tube 12 transmits electromagnetic waves, if the conducting wire 31 is passed through the conduit of the resin tube 12 with the outer periphery of the conducting wire 31 exposed, radio noise from the outside easily enters a weak electric signal from the sensor unit 3. . However, in this embodiment, since the conducting wire 31 is housed in the metal shield tube 32, external radio noise entering the pipe line from the resin tube 12 is caused by the metal shield tube 32 and the circuit portion housing case 12 of the resin tube 12. A weak electrical signal transmitted from the sensor unit 3 to the circuit unit 22 through the conductive wire 31 is protected by the metal plate 33 provided at the end portion on the side. Since the metal shield tube 32 is very thin, the heat conduction by the metal shield tube 32 does not affect the circuit unit 22.

  FIG. 4 is a cross-sectional view showing a flow meter for high-temperature fluid according to another embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member corresponding to the member in embodiment mentioned above, and the detailed description is abbreviate | omitted.

  In the present embodiment, the basic configuration is the same as that of the above-described embodiment, but the metal shield tube 32 is omitted in the most part of the conduit of the metal tube 11. That is, in order to shield the electromagnetic wave, it is necessary to arrange the metal shield tube 32 over the entire pipeline of the resin tube 12, but when the metal tube 11 sufficiently shields the electromagnetic wave, the entire pipeline of the metal tube 11 is not necessarily required. It is not necessary to dispose the metal shield tube 32 over the wire, and the conducting wire 31 can be exposed in the conduit of the metal tube 11. Therefore, in this case, the metal shield tube 32 may be disposed in a region from at least a part of the conduit of the metal tube 11 to the entire conduit of the resin tube 12.

  FIG. 5 is a cross-sectional view showing a flow meter for high-temperature fluid according to another embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member corresponding to the member in embodiment mentioned above, and the detailed description is abbreviate | omitted.

  In the present embodiment, the basic configuration is the same as that of the above-described embodiment, but the entire outer surface 12c of the resin tube 12 is subjected to metal plating, for example, by electroless plating, and external radio noise is thereby caused to occur in the resin tube 12. Shielding from passing to the pipe line. Therefore, it is not necessary to store the conducting wire 31 in the metal shield tube 32 as in the above-described embodiment, and the conducting wire 31 is housed in the conduits of the metal tube 11 and the resin tube 12 as they are and led from the sensor unit 3 to the circuit unit 22. be able to.

In the present embodiment, metal plating is applied to the entire outer surface 12c of the resin tube 12 in order to shield the passage of radio noise into the resin tube 12. However, the present invention is not limited thereto, and the entire inner surface 12d of the resin tube 12 is metal-plated. Alternatively, both the outer surface 12c and the inner surface 12d of the resin tube 12 may be subjected to metal plating. Further, instead of metal plating, a metal thin film is formed on the outer surface 12c, the inner surface 12d or both surfaces of the resin tube 12 by a method such as sputter deposition or application of a conductive paint, thereby externally connecting the resin tube 12 to the outside. You may make it shield the radio wave noise from.

  In the present embodiment, the heat insulating wall 12b is provided inside the pipe at the position of the resin flange portion 12a of the resin pipe 12. The heat insulating wall 12b is integrally formed with the resin pipe 12 by injection molding, and projects from the inner peripheral surface of the resin pipe 12 inwardly to the pipe line. A through hole substantially equal to the diameter of the conducting wire 31 is provided in the central portion of the heat insulating wall 12b, and the conducting wire 31 passes through the through hole.

  The heat insulating wall 12b shields radiation and convection to the circuit portion 22 side inside the metal tube 11. The structure of the heat insulating wall 12b is not limited to the above shape as long as the wall surface is configured so as to effectively shield this radiation and convection, and may have another shape, and its position inside the resin tube 12 Is not limited to the position immediately below the resin flange portion 12a as in this embodiment, but may be a position closer to the circuit portion 22 than that.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the case where the high-temperature fluid flow meter is a vortex flow meter has been described. However, the high-temperature fluid flow meter having another configuration, for example, the rotor is rotated according to the flow rate of the fluid to be measured. A flow meter that measures the flow rate by integrating and displaying the rotation of the rotor, and an electromagnetic flow rate that measures the flow rate by detecting the electromotive force generated when the conductive fluid to be measured flows perpendicular to the magnetic field. The present invention can also be applied to a thermometer, a thermocouple, a heating resistor, a thermal flow meter using a temperature sensitive member such as a semiconductor element having a resistor formed on a semiconductor substrate, and the like.

FIG. 1 is a cross-sectional view showing a flow meter for high-temperature fluid according to an embodiment of the present invention. FIG. 2 is a front view of the high-temperature fluid flow meter of FIG. 1 as viewed from the flow path direction. FIG. 3 is an enlarged cross-sectional view of the periphery of the connection portion between the measurement tube and the sensor. FIG. 4 is a cross-sectional view showing a flow meter for high-temperature fluid according to another embodiment of the present invention. FIG. 5 is a cross-sectional view showing a flow meter for high-temperature fluid according to another embodiment of the present invention.

Explanation of symbols

1 Flowmeter for high temperature fluid (vortex flowmeter)
2 Measuring pipe 2a Pipe line 3 Sensor part 3a Connection part 3b Sensor fixing flange 3c Vortex generator 4 Insulating material 4a Clearance 5 Gasket 11 Metal pipe 11a Metal flange part 11b Pipe part 11c Sensor side flange part 12 Resin pipe 12a Resin flange part 12b Heat insulation wall 12c Outer surface 12d Inner surface 13 Sealing material 14 Screw 15 Fixing plate 16 Nut 21 Circuit portion storage case 22 Circuit portion 31 Conductor 32 Metal shield tube 33 Metal plate 34 Retaining ring 35 Wave washer

Claims (2)

A high-temperature fluid flowmeter that detects a high-temperature fluid to be measured flowing inside a measurement tube with a sensor and guides an electrical signal corresponding to the flow rate output from the sensor to a circuit unit by a conducting wire,
A metal pipe and a resin pipe that lead the lead wire through the pipe to the circuit unit;
Connecting one end of the metal tube to the sensor, connecting a metal flange formed at the other end of the metal tube and a resin flange formed at one end of the resin tube;
In the connecting portion between the metal tube and the resin tube or a position closer to the resin tube than that, a heat insulating wall projecting inward from the inner peripheral surface of the pipe line is provided,
It is arranged in a pipe line from at least a part of the pipe line of the metal pipe to the whole pipe line of the resin pipe, and the conductive wire is housed in a metal shield pipe that shields radio noise from the outside to the electrical signal, A flowmeter for high temperature fluid, wherein the conducting wire led to the end of the resin pipe is connected to the circuit portion. A high-temperature fluid flowmeter that detects a high-temperature fluid to be measured flowing inside a measurement tube with a sensor and guides an electrical signal corresponding to the flow rate output from the sensor to a circuit unit by a conducting wire,
A metal pipe and a resin pipe that lead the lead wire through the pipe to the circuit unit, and a metal thin film is formed on the pipe outer surface and / or the pipe inner surface of the resin pipe;
Connecting one end of the metal tube to the sensor, connecting a metal flange formed at the other end of the metal tube and a resin flange formed at one end of the resin tube;
In the connecting portion between the metal tube and the resin tube or a position closer to the resin tube than that, a heat insulating wall projecting inward from the inner peripheral surface of the pipe line is provided,
A flowmeter for high-temperature fluid, wherein the conducting wire is passed through the pipes of the metal tube and the resin tube, and the conducting wire led to the end of the resin tube is connected to the circuit unit.

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