JP2019164046A - Thermal flowmeter - Google Patents

Abstract

To precisely and accurately measure a flow rate without causing a decrease in strength of piping in a thermal flow rate measurement using the piping made of resin.SOLUTION: A first reinforced pipe 121, a second reinforced pipe 122, and a third reinforced pipe 123 are provided on an outer wall in a thin part 101a of piping 101. The first reinforced pipe 121 and the second reinforced pipe 122 are provided in the thin part 101a while being mutually separated in a longitudinal direction of the piping 101. The first reinforced pipe 121 and the second reinforced pipe 122 cover a periphery of each piping 101 and the inner wall abuts on the outer wall of the piping 101. The third reinforced pipe 123 is made of resin, and the periphery of the piping 101 is covered and the inner wall is formed to abut on the outer wall of the piping 101 in an area other than areas covered with the first reinforced pipe 121 and the second reinforced pipe 122 in the thin part 101a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermal flow meter that measures a flow rate by utilizing an action of thermal diffusion in a fluid.

  Techniques for measuring the flow rate and flow velocity of a fluid flowing through a channel are widely used in the industrial and medical fields. There are various types of devices for measuring flow rate and flow velocity, such as electromagnetic flowmeters, vortex flowmeters, Coriolis flowmeters, and thermal flowmeters. Thermal flow meters have the advantages that they can detect gases, have no pressure loss, and can measure mass flow rates. Such a thermal flow meter for measuring the flow rate of liquid is suitable for measuring a very small flow rate.

  Thermal flow meters include a method for measuring the flow rate based on the temperature difference between the upstream and downstream of the heater and a method for measuring the flow rate based on the power consumption of the heater. For example, when measuring the flow rate of the aqueous solution, the heater temperature is operated by heating at a constant temperature such as plus 10 ° C. with respect to the water temperature, and the flow rate is calculated from the temperature difference between the upstream and downstream or the heater power.

  When such a thermal flow meter is used in a photoresist supply mechanism of a resist coating apparatus, resin piping is used as the piping. This is to prevent contaminants such as metals from entering the photoresist. However, when using resin piping, heat conduction is not very good. For this reason, for example, the fluid to be measured cannot be efficiently heated in a short time, and the temperature of the fluid cannot be measured in a short time, so that there is a problem that the flow rate cannot be measured with high accuracy.

  In order to solve the problem in the case of using the above-described resin piping, a technique has been proposed in which a sensor portion is provided at a location where the tube wall is cut from the outside to make it thinner than other portions (see Patent Document 1). According to this technology, even when resin piping is used, the fluid can be heated more quickly, and temperature changes due to the fluid flow can be detected more quickly, and the flow rate of the fluid to be measured can be controlled with high accuracy. It becomes possible to measure.

JP 2012-202971 A

  However, there is a problem in that the mechanical strength is reduced at a location where the pipe is thinned. As described above, in the case of using a resin pipe, the conventional technique has a problem that accurate flow measurement cannot be performed with high accuracy without causing a decrease in the strength of the pipe.

  The present invention has been made to solve the above problems, and in a thermal flow measurement using a resin pipe, a highly accurate and accurate flow rate can be obtained without causing a reduction in the strength of the pipe. The purpose is to be able to measure.

  A thermal flow meter according to the present invention includes a resin pipe that transports a fluid to be measured, a thin part that is formed in a part of the pipe, and the thickness of the part of the pipe is thinner than the other parts, The first reinforcing pipe and the second reinforcing pipe, which are provided apart from each other in the longitudinal direction of the pipe, cover the circumference of the pipe, and the inner wall contacts the outer wall of the pipe, and the first reinforcing pipe and the second of the thin parts In a region other than the region covered by the reinforcing tube, a third reinforcing tube made of a resin that covers the periphery of the pipe and is in contact with the outer wall of the pipe and the outer wall of the first reinforcing tube is provided in contact with the outer wall of the first reinforcing tube. A temperature measuring unit configured to measure the temperature, a heater provided to contact the outer wall of the second reinforcing pipe, and configured to heat the fluid, at a position not affected by the temperature of the heater and the thermal effect of the heater Set temperature difference in which the difference from the fluid temperature is set A sensor unit configured to output a sensor value corresponding to the state of thermal diffusion in the fluid heated by the heater when the heater is driven, and to calculate the fluid flow rate from the sensor value The first reinforcing pipe and the second reinforcing pipe are made of a material having a higher thermal conductivity than the material forming the third reinforcing pipe.

  In the thermal flow meter, the thin portion is formed in the circumferential direction of the pipe.

  In the thermal flow meter, the thickness of the thin wall portion of the pipe wall of the pipe is constant in the circumferential direction.

  In the thermal flow meter, a plurality of third reinforcing pipes are provided, and at least one of the first reinforcing pipe and the second reinforcing pipe is in contact with the two third reinforcing pipes.

  In the thermal flow meter, the first reinforcing tube and the second reinforcing tube are made of metal, ceramic, or silicon. For example, the metal is copper.

  In the above thermal flow meter, the temperature measurement unit measures the temperature of the fluid upstream of the heater and is not affected by the heat of the heater, and the sensor unit measures the temperature of the heater and the temperature of the fluid measured by the temperature measurement unit. The heater power is output as a sensor value when the heater is driven so that the difference between the two becomes a set temperature difference.

  In the thermal flow meter, the temperature measurement unit includes a first temperature measurement unit, a second temperature measurement unit, and a third temperature measurement unit, and the first temperature measurement unit controls the thermal effect of the heater upstream of the heater. The second temperature measurement unit measures the temperature of the fluid at a position that is affected by the heat of the heater on the upstream side of the heater, and the third temperature measurement unit is on the downstream side of the heater. The temperature of the fluid at a position affected by the heat of the heater is measured, and the sensor unit drives the heater so that the difference between the temperature of the heater and the temperature of the fluid measured by the first temperature measurement unit becomes a set temperature difference. The temperature difference between the fluid temperature measured by the second temperature measurement unit and the fluid temperature measured by the third temperature measurement unit is output as a sensor value.

  As described above, according to the present invention, since the first reinforcing pipe, the second reinforcing pipe, and the third reinforcing pipe are provided in the thin portion, in the thermal flow measurement using the resin pipe, the pipe An excellent effect is obtained in that an accurate flow rate can be measured with high accuracy without incurring a decrease in strength.

FIG. 1 is a configuration diagram showing the configuration of the thermal flow meter in the embodiment of the present invention. FIG. 2A is a cross-sectional view showing a partial configuration of the thermal flow meter in the embodiment of the present invention. FIG. 2B is a cross-sectional view showing a partial configuration of the thermal flow meter in the embodiment of the present invention. FIG. 3 is a configuration diagram showing the configuration of another thermal flow meter according to the embodiment of the present invention.

  Hereinafter, a thermal flow meter according to an embodiment of the present invention will be described with reference to FIGS. 1, 2A, and 2B. The thermal flow meter includes a pipe 101 made of a synthetic resin that transports a fluid to be measured, a sensor unit 102, and a flow rate calculation unit 103. The piping 101 is made of, for example, a fluororesin. The thermal flow meter includes a first reinforcing pipe 121, a second reinforcing pipe 122, and a third reinforcing pipe 123 on the outer wall of the thin portion 101 a of the pipe 101.

  The thin portion 101 a is a region where a part is thinner than the other part of the pipe 101. The thin part 101a has a thinner outer shape than other areas of the pipe 101, for example. Moreover, the thin part 101a is formed in the circumferential direction of the piping 101, for example. In the thin portion 101a, the thickness of the pipe wall of the pipe 101 is constant in the circumferential direction.

  The first reinforcing pipe 121 and the second reinforcing pipe 122 are provided in the thin portion 101a so as to be separated from each other in the longitudinal direction of the pipe 101. The first reinforcing pipe 121 and the second reinforcing pipe 122 each cover the periphery of the pipe 101, and the inner wall is in contact with the outer wall of the pipe 101. The second reinforcing pipe 122 is provided in contact with the outer wall of the pipe 101 on the downstream side of the first reinforcing pipe 121. The 1st reinforcement pipe | tube 121 and the 2nd reinforcement pipe | tube 122 are comprised from the material which has higher heat conductivity than the material which forms the 3rd reinforcement pipe | tube 123 mentioned later. The first reinforcement pipe 121 and the second reinforcement pipe 122 are made of, for example, silicon, ceramic, or metal. The 1st reinforcement pipe | tube 121 and the 2nd reinforcement pipe | tube 122 should just be comprised from copper, for example.

  The third reinforcing pipe 123 is made of resin and covers the periphery of the pipe 101 in an area other than the area covered by the first reinforcing pipe 121 and the second reinforcing pipe 122 in the thin portion 101a, and the outer wall of the pipe 101 Is formed in contact with the inner wall. The third reinforcing pipe 123 is made of, for example, a synthetic resin (plastic). For example, a plurality of third reinforcing pipes 123 are provided, and at least one of the first reinforcing pipe 121 and the second reinforcing pipe 122 is in contact with the two third reinforcing pipes 123.

  In the embodiment, the sensor unit 102 includes a temperature measurement unit 111, a heater 112, a control unit 113, and a power measurement unit 114. The temperature measuring unit 111 is provided in contact with the outer wall of the first reinforcing pipe 121. The heater 112 is provided in contact with the outer wall of the second reinforcing pipe 122. Since the second reinforcing pipe 122 is provided downstream of the first reinforcing pipe 121, the heater 112 is provided downstream of the temperature measuring unit 111. The temperature measuring unit 111 is bonded and fixed to the outer wall of the first reinforcing pipe 121 by, for example, a heat conductive adhesive. The temperature measuring unit 111 measures the temperature of the fluid. The heater 112 is bonded and fixed to the outer wall of the second reinforcing tube 122 by, for example, a heat conductive adhesive.

  Here, the sensor unit 102 drives the heater 112 so that the difference between the temperature of the heater 112 and the temperature of the fluid at a position not affected by the heat of the heater 112 becomes a set temperature difference. The sensor value corresponding to the state of thermal diffusion in the fluid heated by the heater 112 is output. In the embodiment, the difference between the temperature of the heater 112 and the temperature of the heater 112 measured by the temperature measuring unit 111, for example, the temperature of the fluid upstream of the heater 112, is set in advance by the control unit 113. The heater 112 is controlled and driven so as to achieve the set temperature difference.

  The power measuring unit 114 measures and outputs the power of the heater 112 controlled by the control unit 113. The electric power output from the electric power measurement part 114 which comprises the sensor part 102 becomes a sensor value. The flow rate calculation unit 103 calculates the flow rate of the fluid from the power (sensor value) of the heater 112 measured and output by the power measurement unit 114.

  As described above, according to the embodiment, since the thin portion 101a includes the first reinforcing pipe 121, the second reinforcing pipe 122, and the third reinforcing pipe 123, the periphery of the resin pipe 101 is It is possible to suppress a decrease in strength in the thin portion 101a that is made thinner. The first reinforcing pipe 121 provided with the temperature measuring unit 111 and the second reinforcing pipe 122 provided with the heater 112 are made of a material having a higher thermal conductivity than the third reinforcing pipe 123 such as metal, ceramic, or silicon. Therefore, the fluid can be heated quickly and the accuracy of the temperature measurement of the fluid is not lowered. Further, since the thin reinforcing portion 101a around the first reinforcing tube 121 and the second reinforcing tube 122 is provided with the third reinforcing tube 123 made of resin, it is possible to prevent the escape of heat in the flow path direction, and the heater efficiently. 112 heat can be transferred to the fluid.

  Here, operation | movement of the thermal type flow meter in embodiment is demonstrated in detail. As is well known, when the heater 112 is driven so that the difference between the temperature of the heater 112 and the temperature of the fluid at a position not affected by the heat of the heater 112 becomes the set temperature difference, There is a correlation between the power consumed and the fluid flow rate. This correlation is also reproducible at the same fluid / flow rate / temperature. Therefore, as described above, the flow rate calculation unit 103 uses a predetermined correlation coefficient (constant) based on the power measured by the power measurement unit 114 while the heater 112 is controlled by the control unit 113. Can be calculated.

  As shown in FIG. 3, the temperature measuring unit (first temperature measuring unit) 111, the heater 112, the control unit 113, the temperature measuring unit (second temperature measuring unit) 116, and the temperature measuring unit (third temperature measuring unit). The sensor unit 102 ′ may be configured from 117. Each temperature measurement part is provided in contact with the outer wall of the first reinforcing pipe 121a in the thin part 101a. Similar to the above-described embodiment, the first reinforcing pipe 121a is formed so as to cover the periphery of the pipe 101 in a part of the thin part 101a (location where each temperature measurement unit is disposed), and the inner wall is formed on the outer wall of the pipe 101. It is formed in contact. The first reinforcing pipe 121a is made of silicon, ceramic, or metal with good thermal conductivity. The 1st reinforcement pipe | tube 121a should just be comprised from copper, for example.

  The heater 112 is provided in contact with the outer wall of the second reinforcing pipe 122. Further, a third reinforcing pipe 123 is formed over the entire circumference of the thin portion 101 a other than the first reinforcing pipe 121 and the second reinforcing pipe 122 so as to cover the periphery of the pipe 101, and the inner wall is formed on the outer wall of the pipe 101. Is formed in contact.

  In this configuration, the control unit 113 sets in advance a difference between the temperature of the heater 112 and the temperature of the fluid that is measured by the temperature measurement unit 111 and that is not affected by the heat of the heater 112, for example, upstream of the heater 112. The heater 112 is controlled and driven so that the set temperature difference is the same.

  The temperature measuring unit 116 is provided in contact with the outer wall of the first reinforcing pipe 121 a on the downstream side of the temperature measuring unit 111 and on the upstream side of the heater 112. The temperature measurement unit 117 is provided in contact with the outer wall of the first reinforcing pipe 121a on the downstream side of the heater 112. The temperature measuring unit 116 and the temperature measuring unit 117 measure the temperature of the fluid.

  The fluid flow rate can be calculated from the temperature difference between the temperature of the fluid measured by the temperature measuring unit 116 and the temperature of the fluid measured by the temperature measuring unit 117. In this example, the temperature difference between the temperature of the fluid measured by the temperature measuring unit 116 and the temperature of the fluid measured by the temperature measuring unit 117 is the sensor value.

  As is well known, the heater 112 is driven so that the difference between the temperature of the heater 112 and the temperature of the fluid at a position not affected by the heat of the heater 112 becomes a preset temperature difference. There is a correlation between the temperature difference between the temperature of the fluid upstream of the heater 112 and the temperature of the fluid downstream of the heater 112 and the flow rate of the fluid. This correlation is also reproducible at the same fluid / flow rate / temperature. Therefore, as described above, in a state where the heater 112 is controlled by the control unit 113, a predetermined phase is determined based on the difference (temperature difference) between the temperature measured by the temperature measurement unit 116 and the temperature measured by the temperature measurement unit 117. The flow rate can be calculated by using the relation number (constant).

  As described above, according to the present invention, the measurement unit is provided with the first reinforcing pipe, the second reinforcing pipe, and the third reinforcing pipe. Therefore, in the thermal flow measurement using the resin pipe, An accurate flow rate can be measured with high accuracy without reducing the strength of the piping.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious.

  DESCRIPTION OF SYMBOLS 101 ... Pipe, 101a ... Thin part, 102 ... Sensor part, 103 ... Flow rate calculation part, 111 ... Temperature measurement part, 112 ... Heater, 113 ... Control part, 114 ... Electric power measurement part, 121 ... 1st reinforcement pipe, 122 ... 2nd reinforcement pipe, 123 ... 3rd reinforcement pipe.

Claims (8)

A resin pipe that transports the fluid to be measured;
A thin part formed in a part of the pipe and having a thickness of the part of the pipe thinner than the other part,
A first reinforcing pipe and a second reinforcing pipe which are provided in the thin portion apart from each other in the longitudinal direction of the pipe, respectively cover the circumference of the pipe, and the inner wall is in contact with the outer wall of the pipe;
A third reinforcing tube made of a resin that covers the periphery of the pipe and has an inner wall in contact with the outer wall of the pipe in a region other than the region covered with the first reinforcing tube and the second reinforcing tube in the thin portion; ,
A temperature measuring unit provided in contact with the outer wall of the first reinforcing pipe and configured to measure the temperature of the fluid, provided in contact with the outer wall of the second reinforcing pipe, and configured to heat the fluid When the heater is driven so that the difference between the temperature of the heater and the temperature of the fluid at a position not affected by the heat of the heater is a set temperature difference that is set, A sensor unit configured to output a sensor value corresponding to a state of thermal diffusion in the fluid heated by the heater;
A flow rate calculation unit configured to calculate the flow rate of the fluid from the sensor value;
The thermal flow meter, wherein the first reinforcing pipe and the second reinforcing pipe are made of a material having a higher thermal conductivity than a material forming the third reinforcing pipe. The thermal flow meter according to claim 1, wherein
The thin portion is formed in a circumferential direction of the pipe. The thermal flow meter according to claim 1 or 2,
In the thin-walled portion, the thickness of the pipe wall of the pipe is constant in the circumferential direction. In the thermal type flow meter according to any one of claims 1 to 3,
A plurality of the third reinforcing pipes are provided, and at least one of the first reinforcing pipe and the second reinforcing pipe is in contact with the two third reinforcing pipes. In the thermal type flow meter according to any one of claims 1 to 4,
The first reinforcing pipe and the second reinforcing pipe are made of metal, ceramic, or silicon. The thermal flow meter according to claim 5, wherein
The thermal flowmeter, wherein the metal is copper. In the thermal type flow meter according to any one of claims 1 to 6,
The temperature measuring unit measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater;
The sensor unit is configured to measure the electric power of the heater when the heater is driven so that a difference between the temperature of the heater and the temperature of the fluid measured by the temperature measurement unit becomes the set temperature difference. A thermal flowmeter that outputs as a value. In the thermal type flow meter according to any one of claims 1 to 6,
The temperature measuring unit includes a first temperature measuring unit, a second temperature measuring unit, and a third temperature measuring unit,
The first temperature measurement unit measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater,
The second temperature measurement unit measures the temperature of the fluid at a position that is affected by the heat of the heater upstream of the heater,
The third temperature measurement unit measures the temperature of the fluid at a position that is affected by the heat of the heater downstream from the heater,
The sensor unit drives the heater so that a difference between a temperature of the heater and a temperature of the fluid measured by the first temperature measurement unit becomes the set temperature difference. A thermal flow meter characterized in that a temperature difference between the temperature of the fluid measured by the measurement unit and the temperature of the fluid measured by the third temperature measurement unit is output as the sensor value.

Images