JP5580396B2 - Fluid sensor and fluid measuring device - Google Patents

Description

  The present invention relates to a fluid measurement device and a fluid sensor that measure the mass, attribute, and the like of a fluid using physical characteristics that are unique to the fluid such as gas and liquid.

  As a device for measuring the mass of a fluid using physical properties of the fluid, a fluid measuring device disclosed in Patent Document 1 is known. This fluid measuring device is called a mass flow meter. This mass flow meter is provided with a bypass channel for bypassing the fluid and a sensor channel for measuring the flow rate of the fluid in parallel. The sensor flow path is formed by a stainless steel (SUS) hollow thin tube having an inverted U shape, and a thermoelectric sensor is provided on the surface thereof.

  When the fluid is divided into the sensor flow path, the temperature on the upstream side decreases, and conversely, on the downstream side, the heat on the upstream side is heated and increases. At this time, the temperature difference generated between the upstream side and the downstream side is proportional to the flow rate of the fluid. Therefore, the upstream temperature of the sensor flow path is measured by the upstream thermoelectric sensor, and the downstream temperature is measured by the downstream thermoelectric sensor. The measurement result of each sensor is converted into the flow rate of the sensor flow path. The mass flow meter converts the converted flow rate into the flow rate of the bypass flow path in accordance with the diversion ratio of the sensor flow path to the bypass flow path.

JP 2003-149017 A

The sensor flow path of the mass flow meter described in Patent Document 1 is made of stainless steel (SUS). However, when SUS is used, there is a problem that ionization occurs because it contains chromium and nickel, which leads to metal contamination.
In some fluid measuring devices, the bypass channel and the sensor channel are made of a tetrafluoroethylene resin (trade name “Teflon”) material. Since Teflon-based materials have low thermal conductivity, they are usually used as a coating film. However, Teflon is a rough material, and therefore it is permeated depending on the fluid. In order to prevent permeation, it is necessary to increase the thickness of the Teflon film. However, it becomes difficult to correctly detect the temperature change between the upstream side and the downstream side of the sensor flow path due to the temperature gradient. Further, Teflon is charged by friction when an insulating fluid such as pure water is passed, and there is a risk of discharging when the amount of charge increases.

  The conventional fluid measuring device including the mass flow meter described in Patent Document 1 is not suitable for measuring such a fluid because a sensor flow path is corroded when a highly acidic or strongly alkaline fluid is flowed. . In addition, there is no fluid measuring device that has chemical resistance and can be used for most chemical solutions. Furthermore, there is a problem that the mass and the like of the fluid in which bubbles are mixed cannot be measured correctly.

  It is an object of the present invention to provide a fluid measuring device and its components that can measure the characteristics of many types of fluids without causing metal contamination.

The fluid measuring device of the present invention includes a main channel pipe that forms a main channel through which a fluid composed of gas, liquid, or a mixture thereof flows, and a sub channel that divides the fluid introduced into the main channel at a predetermined ratio. And a fluid sensor configured to detect the characteristics of the fluid flowing in the sub-flow channel. The characteristics of the fluid are, for example, resistance (purity), heat or electron conductivity, mass flow rate, and the like.
Each of the main channel tubes includes a plurality of thin tubes that move the fluid upstream of the main channel to the downstream side. Each thin tube is made of a carbon material maintained at ground potential.
The fluid sensor has an inflow port through which the fluid on the upstream side of the main channel flows in by hollowing out the inside of the corrosion-resistant insulator into a curved tube, and an outflow port for outflowing the fluid to the downstream side of the main channel. Between the formed sub-flow channel forming body, the first sensor pipe disposed between the inlet and the upstream side of the main channel, and between the outlet and the downstream side of the main channel. And a second sensor pipe provided.
In each of the first sensor tube and the second sensor tube, there are movable cores that rotate around an axis to urge the inflowing fluid spirally toward the inner wall. It is provided along the axis. Further, the first sensor tube and said second sensor tube is composed of a carbon material which is maintained at ground potential, respectively, the characteristics of the fluid flowing through the tube, to enable detection through the carbon material.

The present invention also provides a fluid sensor. The fluid sensor of the present invention is attached to a main channel pipe through which a fluid composed of gas, liquid, or a mixture thereof flows, and an inflow port through which the fluid flows in by corrugating the inside of the corrosion-resistant insulator, and A sub-flow channel forming body in which an outflow port for allowing the fluid to flow out is formed, a first sensor tube disposed between the inflow port and the main flow channel tube, and the outflow port and the main flow channel tube A second sensor tube disposed between and
In each of the first sensor tube and the second sensor tube, there are movable cores that rotate around an axis to urge the inflowing fluid spirally toward the inner wall. It is provided along the axis. Further, the first sensor tube and said second sensor tube is composed of a carbon material which is maintained at ground potential, respectively, the characteristics of the fluid flowing through the tube, to enable detection through the carbon material.

In the fluid measuring device of the present invention, since the plurality of thin tubes that respectively move the fluid upstream of the main flow path to the downstream are made of a carbon material that is maintained at the ground potential, charging can be prevented. In addition, the fluid sensor is formed with an inflow port through which the fluid on the upstream side of the main channel flows in by hollowing out the inside of the corrosion resistant insulator into a curved tube, and an outflow port through which the fluid flows out to the downstream side of the main channel Since the sub-flow channel forming body is provided, permeation of fluid can be prevented.
When glassy carbon is used as the carbon element, it exhibits corrosion resistance and chemical resistance, is excellent in thermal and electrical conductivity, and is less likely to generate particles, thereby realizing a versatile fluid measuring device.

(A) is side surface sectional drawing which shows the principal part structural example of the fluid measuring apparatus of 1st Embodiment, (b) is AA sectional drawing of (a). (A) is side sectional drawing of a thin tube, (b) is front sectional drawing. It is the elements on larger scale which extracted the part of the fluid sensor from Fig.1 (a). It is explanatory drawing of the attachment state of a thermoelectric conversion sensor. It is a figure showing the connection relation with the control apparatus of the back | latter stage of a fluid measuring apparatus. It is the figure which showed typically the structure of the fluid measuring apparatus of 2nd Embodiment.

Hereinafter, embodiments of the fluid measuring device will be described.
[First Embodiment]
The fluid measurement device according to the first embodiment measures the mass flow rate of a fluid that is gas, liquid, or a mixture thereof. FIG. 1A is a side cross-sectional view showing an example of the main structure of the fluid measuring apparatus 100, and FIG. 1B is a cross-sectional view taken along line AA of FIG.

  The fluid measuring apparatus 100 is configured by connecting a main flow path pipe 10 through which a fluid flows and a fluid sensor 20. The main channel tube 10 is formed of a corrosion resistant insulator, for example, a hollow tubular body formed by molding a tetrafluoroethylene resin (trade name “Teflon”) into a predetermined shape, and includes an upstream channel 11, a downstream channel 12, and The bypass channel 13 is provided and configured.

The upstream flow path 11 introduces fluid from a first external device (not shown) on the upstream side. The downstream flow path 12 guides the fluid discharged from the bypass flow path 13 to the second external device (not shown) on the downstream side 12. The “upstream side” is the side into which the fluid flows, and the “downstream side” refers to the side from which the fluid flows out. The bypass channel 13 is configured by arranging n (n is a natural number of 2 or more) thin tubes 131 in the same direction. The n thin tubes 131 bypass the fluid in the upstream channel 11 to the downstream channel 12 except for branching to the fluid sensor 20. Thereby, the flow rate of the fluid flowing through the main channel 10 can be quantified by the flow rate of the thin tubes 131 and the number thereof.
In addition, the number of the thin tubes 131 can be increased or decreased arbitrarily.

  The structure of each capillary 131 is shown in FIG. 2A is a side sectional view of the thin tube 131, and FIG. 2B is a front sectional view. The narrow tube 131 includes a tube 132 formed of glassy carbon and a movable core 133 built in the tube 132. The tube 132 is maintained at the ground potential. That is, a ground wire (ground wire) is connected to the surface of the tubular body.

The movable core 133 has a spiral blade 134 formed on the outer surface. The blade 134 is an urging member for moving the fluid from the upstream side to the downstream side while urging the fluid in a spiral shape, and the direction of the spiral is from the upstream side (inlet) to the downstream side (outlet). Is formed. Therefore, the movable core 133 autonomously rotates about the axis when the fluid flowing into the tube body 132 pushes the blades 134. Then, the inflowing fluid is discharged to the outlet side of the tube body 132 while contacting the inner wall of the tube body 132.
In the narrow tube 131, there may be a temperature difference between the central portion near the axis and the inner wall. However, by incorporating the movable core 133, most of the fluid comes into contact with the tube 132, and the fluid Can be correctly transmitted to the tube 132.

The glassy carbon constituting the tube 132 is a kind of carbon material, and has characteristics of both glass and carbon. Typically, for example, it has the following characteristic values.
Bulk density: 1.51 [g / cm ³ ]
Electrical resistivity: 42 [μΩm]
Bending strength: 147 [MPa] (however, 1500 [kgf / cm ² ])
Shore hardness: 120 (-)
Ash content: Less than 2 [ppm]
Thermal conductivity: 5.8 [W / mK] (However, 5.1 [kcal / mhr ° C])

Further, the weight change when glassy carbon having an inner diameter of 3.0 [mm] is immersed in sulfuric acid of 98% concentration for 7 days is 0%. The same applies when immersed in hydrofluoric acid, 50% strength caustic soda and 28% strength aqueous ammonia. Thus, the glassy carbon does not cause a material change with respect to strong acidity and strong alkalinity.
Glassy carbon also does not output metal ions and therefore does not cause metal contamination. Further, since the gas, liquid, and mixture thereof are not permeated, for example, the fluid introduced at the previous measurement is not mixed with the fluid flowing at the next measurement. That is, it is excellent in contamination resistance. Furthermore, since it is a carbon material, it has excellent heat and electron conductivity. Furthermore, since it has a hardness similar to that of diamond, it is difficult for carbon powder (particles) to be produced.
By using the glassy carbon having such features for the tube 132 of the thin tube 131 and maintaining the tube 132 at the ground potential, it becomes possible to take measures against charging when the fluid flows. That is, it is possible to prevent charging caused by the flow of fluid.

  Returning to FIG. 1, a sensor mounting mechanism 15 is formed in a portion of the outer wall of the main channel pipe 10 corresponding to the upstream channel 11 and the downstream channel 12. The fluid sensor 20 is attached to the sensor mounting mechanism 15. The sensor mounting mechanism 15 is formed, for example, by forming a pedestal 151 made of Teflon in accordance with the shape of the outer wall of the main flow path tube 10 and mounting the fluid sensor 20 on the pedestal 151.

  FIG. 3 shows the fluid sensor 20 extracted from the side sectional view of FIG. Referring to FIG. 3, the fluid sensor 20 includes a sub flow channel forming body 21, an upstream sensor tube 22, and a downstream sensor tube 23 for forming a sub flow channel. The auxiliary flow path forming body 21 is formed with an inflow port 211 for allowing a fluid to flow in and an outflow port 212 for allowing the fluid to flow out by hollowing out the inside of the corrosion-resistant insulator into a tubular shape. The inflow port 211 and the outflow port 212 are cut out in a direction substantially orthogonal to the main flow path pipe 10 (bypass flow path 13). The remaining portion 213 of the corrosion-resistant insulator is cut out in parallel with the main channel tube 10 via an R shape, that is, a curved tube. Thus, the reason why the flow path is formed by hollowing out is to prevent the permeation of fluid by setting the thickness of the corrosion-resistant insulator to a certain level or more. As the corrosion resistant insulator, Teflon can be used in the same manner as the main channel tube 10.

The upstream sensor tube 22 and the downstream sensor tube 23 are the same as the narrow tube 131 described above. That is, it is configured to include a tube body made of glassy carbon and a movable core built in each tube body. Each sensor tube 22, 23 is also maintained at ground potential.
The number of the sensor pipes 22 and 23 is not necessarily one as shown in the figure, but when each sensor pipe is constituted by one, the shunt ratio with the main channel pipe 10 is 1 / n. The diversion ratio is the ratio of the flow rate between the branch point and the merge point in the main flow channel 10 (bypass flow channel 13) to the flow rate of the sub flow channel forming body 21.

  As shown in FIG. 4, a thermoelectric conversion sensor 221 that converts the temperature of the sensor tube 22 into an electric signal is attached to the surface of the upstream sensor tube 22, and the sensor tube 23 is attached to the surface of the downstream sensor tube 23. A thermoelectric conversion sensor 231 for converting the temperature of the current into an electric signal is attached. Specifically, for example, a coil-shaped heat sensitive resistor whose electric resistance value increases or decreases as the temperature of each of the sensor tubes 22 and 23 changes is wound. When no fluid is flowing through each sensor tube 22, 23, the temperature distribution is symmetrical with respect to the center of each sensor 22, 23. On the other hand, when the fluid flows into the sensor tubes 22 and 23, the fluid heated by the upstream sensor tube 22 flows into the downstream sensor tube 23. Therefore, the temperature is higher than that of the upstream sensor tube 22, and a temperature difference is formed between the upstream sensor tube 22 and the downstream sensor tube 23. As a result, the temperature distribution becomes asymmetric. A certain relationship is established between the temperature difference at this time and the flow rate of the fluid. Therefore, by detecting this temperature difference, the flow rate of the fluid diverted to the fluid sensor 20 can be measured.

  In this embodiment, in order to measure the flow rate of the fluid diverted to the fluid sensor 20 as described above, the detection results of the thermoelectric conversion sensors 221 and 231 are transmitted to the control device at the subsequent stage.

FIG. 5 is a diagram illustrating a connection relationship between the fluid measurement device 100 of the present embodiment and the control device at the subsequent stage. The fluid measuring device 100 shown in FIG. 1 is schematically expressed as in the lower part of FIG. The control device 25 includes a bridge circuit 253, a calculation unit 254, a flow rate display unit 255, a setting unit 256, a comparison unit 257, and a flow rate control unit 258.
The outputs of the thermoelectric conversion sensors 221 and 231 are converted into voltage values representing the temperature difference between the thermoelectric conversion sensors 221 and 231 in the bridge circuit 253 and guided to the calculation unit 254. The computing unit 254 obtains the flow rate of the fluid diverted to the fluid sensor 20 based on the output result of the bridge circuit 251 and a predetermined function. Furthermore, the flow rate of the main flow path pipe 10 is obtained based on the flow rate of the diverted fluid and the diversion ratio (n: 1) described above. Each flow rate obtained by the calculation unit 254 is displayed on the flow rate display unit 255.
Further, the flow rate of the fluid in the main channel pipe 10 and the set flow rate (set value) set in the setting unit 256 are compared by the comparison unit 257, and the difference value is transmitted to the flow rate control unit 258. The flow control unit 258 controls the flow rate of the first external device on the upstream side so that the difference value approaches zero.

Thus, the fluid sensor 20 of the present embodiment forms the inflow port 211, the flow path 213, and the outflow port 212 by hollowing out the inside of Teflon, which is an example of a corrosion-resistant insulator, into a curved tube shape. Fluid permeation can be prevented. Since the characteristics of the fluid are determined by the upstream sensor tube 22 and the downstream sensor tube 23, there is no problem even if the Teflon is thick.
Since the upstream sensor tube 22 and the downstream sensor tube 23 are made of glassy carbon maintained at ground potential, they do not cause metal contamination and are highly acidic, strongly alkaline, and highly resistant to chemicals. Demonstrate sex. It also has excellent anti-contamination, heat and electron conductivity, so the (mass) flow rate of fluid can be measured with high accuracy.
In addition, it is possible to take measures against charging when the fluid flows. That is, it is possible to prevent charging caused by the flow of fluid. Furthermore, since the same material and the same size as the narrow tube 13 constituting the main flow channel tube 10, the setting of the flow dividing ratio becomes easy.

  In the present embodiment, the movable core 133 in which the spiral blades 134 are formed is incorporated in the tube body 132 of the thin tube 13 so that the fluid is moved from the upstream side to the downstream side while energizing the spiral. Therefore, most of the fluid comes into contact with the tube 132, and the temperature of the fluid can be correctly transmitted to the tube 132. Thereby, the measurement error of the flow rate can be reduced.

[Second Embodiment]
Next, a fluid measuring device according to a second embodiment will be described. FIG. 6 is a diagram schematically illustrating the configuration of the fluid measuring device 200 according to the second embodiment. The main flow path unit 10 is the same as the fluid measurement device 100 in the first embodiment. In the fluid measurement device 200 of this embodiment, in the fluid sensor 20 of the first embodiment, the output results of the thermoelectric conversion sensors 221 and 231 are input to the ammeter 311 to measure the current, and each capillary tube of the bypass flow path 13 is measured. A voltmeter 312 is connected to 131 to measure the charging voltage. Then, the resistance value is obtained from the output results of the ammeter 311 and the voltmeter 312. Since the purity of pure water can be expressed as a function of the resistance value, the purity of the fluid can be measured by obtaining the resistance value.

  DESCRIPTION OF SYMBOLS 100,200 ... Fluid measuring apparatus, 10 ... Main channel pipe, 11 ... Upstream channel, 12 ... Downstream channel, 13 ... Bypass channel, 131 ... Narrow tube, 132 ... Tube, 133 ... Movable core, 134 ... Blade, 15 ... Sensor mounting mechanism, 151 ... Base, 20 ... Fluid sensor, 21 ... Sub-channel formation body 22 ... upstream sensor tube, 23 ... downstream sensor tube, 211 ... inlet, 212 ... outlet, 213 ... sub-flow channel, 221,231 ... thermoelectric sensor 25 ... Control device 253 ... Bridge circuit 254 ... Calculation unit 255 ... Flow rate display unit 256 ... Setting unit 257 ... Comparison unit 258 ... Flow rate control 311 ... ammeter, 312 ... voltmeter.

Claims (4)

It is attached to the main channel pipe through which a fluid consisting of gas, liquid or a mixture thereof flows,
A sub-flow channel forming body in which an inflow port through which the fluid flows in by hollowing out the inside of the corrosion-resistant insulator into a curved tube, and an outflow port through which the fluid flows out;
A first sensor pipe provided between the inlet and the main flow path pipe;
A second sensor pipe provided between the outlet and the main channel pipe;
In each of the first sensor tube and the second sensor tube, a movable core that urges the fluid that flows in spirally toward the inner wall by rotating about the axis. Provided along the axis ,
The first sensor tube and the second sensor tube are each composed of a carbon material maintained at a ground potential, and the characteristics of the fluid flowing in the tube can be detected through the carbon material.
Fluid sensor. The carbon material is glassy carbon,
The fluid sensor according to claim 1. A main channel tube forming a main channel through which a fluid composed of gas, liquid or a mixture thereof flows;
Forming a sub-flow path for diverting the fluid introduced into the main flow path at a predetermined ratio, and detecting a characteristic of the fluid flowing in the sub-flow path;
The main channel pipe includes a plurality of thin tubes that move the fluid upstream of the main channel to the downstream side, and each thin tube is formed of a carbon material that is maintained at a ground potential.
The fluid sensor is
A side flow in which an inflow port for allowing the fluid on the upstream side of the main channel to flow in by hollowing out the inside of the corrosion-resistant insulator into a curved tube and an outflow port for flowing the fluid to the downstream side of the main channel are formed. A path former,
A first sensor pipe provided between the inlet and the upstream side of the main flow path;
A second sensor pipe provided between the outlet and the downstream side of the main flow path,
In each of the first sensor tube and the second sensor tube, a movable core that urges the fluid that flows in spirally toward the inner wall by rotating about the axis. Provided along the axis ,
The first sensor tube and the second sensor tube are each composed of a carbon material maintained at a ground potential, and the characteristics of the fluid flowing in the tube can be detected through the carbon material.
Fluid measuring device. The carbon material is glassy carbon,
The fluid measuring device according to claim 3.