JP5634636B1 - Ultrasonic flow meter - Google Patents

Abstract

[PROBLEMS] To suppress the thermal expansion of a fluororesin measurement pipe line to stabilize the shape and increase the mechanical rigidity of the fluororesin measurement pipe line, and to provide a temperature sensor and the like on the fluororesin measurement pipe line To provide an ultrasonic flowmeter that maintains high-precision flow measurement over a long period of time without being attached. SOLUTION: Ultrasonic transceivers 140 and 150 are arranged on the upstream side and the downstream side of a fluorine resin measurement pipe line 110 through which a fluid F to be measured flows, and the outer peripheral surface of the fluorine resin measurement pipe line 110 is provided. Are fitted to the outer tube 160 made of carbon fiber reinforced resin in close contact with each other, and an ultrasonic beam is transmitted from one of the ultrasonic transceivers 140 and 150 into the fluid F to be measured in the measurement pipe 110 made of fluororesin. Then, the fluororesin measurement pipe 110 is received from the time difference between the time when the ultrasonic beam is received by the other of the ultrasonic transmitters / receivers 140 and 150 and the time when the ultrasonic beam propagates from the upstream side to the downstream side and the time when the ultrasonic beam propagates from the downstream side to the upstream side. A time difference type ultrasonic flowmeter 100 for obtaining a flow rate of the fluid F to be measured flowing through the fluororesin measuring pipe 110 by obtaining a velocity of the fluid F to be measured flowing therein. [Selection] Figure 1

Description

  The present invention provides a time difference between a time during which an ultrasonic beam generated from an ultrasonic transmitter / receiver propagates from the upstream side to the downstream side of a fluororesin measurement conduit through which a fluid to be measured flows and a time during which the ultrasonic beam propagates from the downstream side to the upstream side. Calculate the fluid velocity in the fluororesin measurement pipe from the flow rate and multiply the fluid velocity by the cross-sectional area of the fluororesin measurement pipeline to find the flow rate in the fluororesin measurement pipeline. It relates to flowmeters, and in particular, various chemicals used in equipment for polishing and cleaning silicon wafers in the manufacturing process of semiconductors and liquid crystals, liquid crystal production equipment, raw materials in food production lines and chemical production lines, storage, The present invention relates to an ultrasonic flowmeter for measuring a liquid such as a chemical solution handled in a mixing process.

  Conventionally, as a time difference type ultrasonic flowmeter, two ultrasonic transmitters / receivers that are attached to the outer peripheral surface of the measuring tube through which the fluid to be measured flows are separated in the axial direction, and transmitted from one of these two ultrasonic transmitters / receivers. The received ultrasonic vibration is received by the other of the two ultrasonic transmitters / receivers via the fluid to be measured in the measuring tube, and the ultrasonic waves between the two ultrasonic transmitters / receivers are switched alternately between the transmitting and receiving ultrasonic transmitters / receivers. There is an ultrasonic flowmeter that measures the flow velocity of a fluid to be measured by measuring the propagation time (for example, Patent Document 1).

  In this ultrasonic flowmeter, the material of the measuring tube through which the fluid to be measured flows is easy to process due to chemical resistance and excellent moldability, and also propagates at a speed of sound slower than the speed of sound in the fluid to be measured. Fluorine resin that does not affect the propagation of ultrasonic vibration is used.

Japanese Patent Laying-Open No. 2005-188974 (in particular, refer to claim 6 and FIG. 1)

  However, in the conventional ultrasonic flowmeter, when the diameter of a measuring tube made of a fluororesin having excellent chemical resistance and moldability and a high coefficient of thermal expansion changes due to thermal expansion, for example, a measuring tube made of a fluororesin When the temperature exceeds 140 ° C., deformation of 10% or more occurs, the flow passage cross-sectional area of the measuring tube changes, the magnitude of the flow velocity is affected, and ultrasonic transducers are arranged on the upstream and downstream sides. If the length of the measurement tube made of fluorine resin changes due to thermal expansion, the propagation path length of the ultrasonic beam also changes and the propagation time of the ultrasonic beam is affected. There has been a problem that changes in diameter and length due to thermal expansion cause measurement errors.

  In addition, measurement pipes made of fluororesins with excellent moldability of conventional ultrasonic flowmeters are placed on the upstream and downstream sides because their mechanical rigidity decreases due to an increase in environmental temperature, fluid temperature to be measured, and aging. Since the minute change in the mutual spatial position of the ultrasonic transmitter / receiver causes a positional shift such as center line and parallelism and zero point drift between ultrasonic beams that require high accuracy, There was a problem that it interfered with transmission and reception and caused measurement errors.

  Furthermore, with conventional ultrasonic flowmeters, the dimensions and shape of a measurement tube made of a fluororesin with a high coefficient of thermal expansion are unstable with respect to temperature changes and secular changes, resulting in measurement errors in long-term flow measurement. For this reason, there is a troublesome problem in the configuration of the apparatus in that a temperature sensor, a strain sensor, etc. are attached to the measurement tube, and this measurement error must be corrected by a calculation unit such as a converter (not shown) that is electrically connected. It was.

  Therefore, the present invention solves the above-mentioned problems of the prior art, that is, the object of the present invention is to suppress the change in the cross-sectional area of the flow path due to the thermal expansion of the fluororesin measuring pipe. Stabilize and improve measurement accuracy and increase the mechanical rigidity of fluororesin measurement pipes for long-term accurate flow measurement without attaching a temperature sensor to the fluororesin measurement pipes It is to provide an ultrasonic flow meter that is maintained over time.

  In the invention according to claim 1, ultrasonic transmitters / receivers are respectively arranged on the upstream side and the downstream side of a fluororesin measurement pipe for flowing a fluid to be measured, and one of the ultrasonic transmitters / receivers is made of a fluororesin. An ultrasonic beam is transmitted into the fluid to be measured in the measurement pipe and received by the other of the ultrasonic transmitter / receiver, and the ultrasonic beam propagates from the upstream side to the downstream side and propagates from the downstream side to the upstream side. A time difference type ultrasonic flowmeter that obtains the flow rate of the fluid under measurement flowing through the fluororesin measurement pipe by obtaining the velocity of the fluid under measurement flowing through the fluororesin measurement pipe from the time difference from In order to suppress changes in the cross-sectional area of the flow path due to thermal expansion of the fluororesin measurement pipe, the fluororesin measurement pipe is in close contact with the outer peripheral surface of the fluororesin measurement pipe For carbon fiber reinforced resin jackets By Te are fitted, it is to solve the aforementioned problems.

  In addition to the configuration of the ultrasonic flowmeter according to the first aspect, the invention according to the second aspect has a cross-sectional shape in which the measurement pipe made of fluororesin is formed at a temperature lower than the minimum use temperature of the fluid to be measured. The above-described problems are solved by being tightly fixed to the carbon fiber reinforced resin outer tube.

  In the invention according to claim 3, in addition to the configuration of the ultrasonic flowmeter according to claim 1 or 2, the carbon fiber reinforced resin outer tube is arranged upstream of the fluororesin measurement pipe. The problem described above is solved by providing the entire length of the ultrasonic beam propagation region between the side and the downstream side.

  In addition to the configuration of the ultrasonic flowmeter according to any one of claims 1 to 3, the invention according to claim 4 includes an upstream side and a downstream side of the fluororesin measurement pipe line. The above-described problems are solved by connecting the ultrasonic transmitters / receivers arranged with each other by the carbon fiber reinforced resin outer tube.

  The ultrasonic flowmeter of the present invention has an ultrasonic transmitter / receiver arranged on the upstream side and the downstream side of a fluororesin measurement pipe for flowing a fluid to be measured, and the fluororesin measurement is performed from one side of the ultrasonic transmitter / receiver. By transmitting an ultrasonic beam into the fluid to be measured in the pipe and receiving it by the other of the ultrasonic transmitter / receiver, the ultrasonic beam propagates from the upstream side to the downstream side and propagates from the downstream side to the upstream side. The flow rate of the fluid to be measured flowing in the fluororesin measurement pipe line can be obtained from the time difference from the time to obtain the flow rate of the fluid to be measured flowing in the fluororesin measurement pipe line. It is possible to achieve a unique effect.

That is, according to the ultrasonic flowmeter of the first aspect of the present invention, the fluororesin measurement pipe line is in close contact with the outer peripheral surface of the fluororesin measurement pipe line to the carbon fiber reinforced resin mantle pipe. Fluorine-based resin measuring tube, even if it is affected by temperature changes in the measurement environment and the temperature of the fluid being measured during flow measurement, or due to changes in the flow path shape over time. Measurements made of fluororesin because the carbon fiber reinforced resin sheath tube, which is extremely smaller than the thermal expansion coefficient of the channel and has high mechanical rigidity, suppresses changes in the cross-sectional area of the channel due to thermal expansion of the fluororesin measurement pipe Not only can the measurement accuracy be improved by stabilizing the shape of the pipe, but the mechanical rigidity of the fluororesin measurement pipe is increased, and a temperature sensor is attached to the fluororesin measurement pipe. Highly accurate flow measurement without any It can be maintained for a long period of time.
Moreover, since the outer tube made of carbon fiber reinforced resin does not propagate ultrasonic vibration, the ultrasonic beam reliably propagates in the measurement pipe made of fluororesin, further improving the measurement accuracy. In order to reduce the static charge on the manufactured measurement pipe, measures such as the influence on the measurement circuit due to the charge, the destruction of the circuit element, and the ignition of the flammable gas can be easily achieved.

  According to the ultrasonic flowmeter of the invention according to claim 2, in addition to the effect of the invention according to claim 1, the cross section formed by the fluororesin measurement pipe line below the minimum operating temperature of the fluid to be measured With the shape and tightly fixed to the carbon fiber reinforced resin sheath tube, the temperature of the fluid to be measured at the time of flow rate measurement will change to a temperature higher than the minimum operating temperature, and the fluororesin measurement pipeline will expand thermally However, the carbon fiber reinforced resin outer tube having a higher tensile strength than the fluororesin measurement pipe line reliably suppresses the thermal expansion of the fluororesin measurement pipe line. In order to keep the flow path cross-sectional area constant, the velocity of the fluid to be measured flowing in the fluororesin measurement pipe line based on the flow path cross-sectional area in the predetermined fluororesin measurement pipe line kept stable. The flow rate of the fluid to be measured can be calculated more accurately from A situation where the fluororesin measurement pipe line formed at a temperature higher than the minimum operating temperature of the constant fluid shrinks inside the carbon fiber reinforced resin jacket pipe and the flow rate of the fluid to be measured cannot be accurately obtained is avoided. can do.

  According to the ultrasonic flowmeter of the invention of claim 3, in addition to the effect of the invention of claim 1 or claim 2, the carbon fiber reinforced resin sheath tube is a fluororesin measurement pipe line. By providing the entire length of the ultrasonic beam propagation region between the upstream side and the downstream side, the fluororesin measurement pipe line can be used to prevent temperature changes in the measurement environment and fluid temperature during measurement. Even if it is affected, in order to ensure a predetermined ultrasonic beam propagation path length without expanding or contracting the pipe length of the fluororesin measurement pipe line, it is necessary to use an ultrasonic wave based on this stable predetermined ultrasonic beam propagation path length. The velocity of the fluid to be measured flowing in the fluororesin measuring pipe is determined from the time difference between the time of propagation from the upstream side to the downstream side of the acoustic beam and the time of propagation from the downstream side to the upstream side. Fluororesin measurement from speed Can be determined the flow rate of the fluid to be measured flowing through the road more accurately.

  According to the ultrasonic flowmeter of the invention according to claim 4, in addition to the effect exerted by the invention according to any one of claims 1 to 3, the upstream side and the downstream side of the fluororesin measurement pipe line The ultrasonic transmitter / receiver placed on each side is connected to each other by a carbon fiber reinforced resin sheath tube, so that the fluororesin measurement pipe line changes the temperature of the measurement environment and the temperature of the fluid to be measured during flow rate measurement. Even if it is affected by changes or the influence of aging of the flow path shape, it is securely held without changing the mounting form of the ultrasonic transceivers that are positioned facing and spaced apart from each other. The center line, parallelism, and other misalignments and zero point drift that tend to occur between instruments are suppressed, preventing fluctuations in the propagation path and path length of the ultrasonic propagation beam due to the effects of temperature changes and aging. Over the long term It is possible to maintain the flow measurement of a constant and accurate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view showing an outline of an ultrasonic flowmeter according to a first embodiment of the present invention. The principal part enlarged view of the inflow side of the ultrasonic flowmeter shown by the code | symbol A of FIG. III-III sectional drawing in FIG. Front sectional drawing which shows the outline of the ultrasonic flowmeter which is 2nd Example of this invention. VV sectional drawing in FIG.

  In the present invention, ultrasonic transmitters / receivers are respectively arranged on the upstream side and the downstream side of a fluororesin measurement pipeline through which a fluid to be measured flows. Fluorine based on the time difference between the time that the ultrasonic beam propagates from the upstream side to the downstream side and the time that the ultrasonic beam propagates from the downstream side to the upstream side. In a time difference type ultrasonic flowmeter that calculates the flow rate of the fluid under measurement flowing through the resin measurement pipe and determining the flow rate of the fluid under measurement flowing through the fluorine resin measurement pipe, In order to suppress changes in the cross-sectional area of the flow path due to thermal expansion, the fluororesin measurement pipe line is fitted to the carbon fiber reinforced resin mantle pipe in close contact with the outer peripheral surface of the fluororesin measurement pipe line. The thermal expansion of the fluororesin measurement pipe line Suppresses changes in the cross-sectional area of the flow path, stabilizes the shape and improves measurement accuracy, and increases the mechanical rigidity of the fluororesin measurement pipe line and adds a temperature sensor to the fluororesin measurement pipe line. As long as high-precision flow rate measurement is maintained over a long period of time without being attached, any specific form may be used.

  That is, the fluid to be measured that is measured by the ultrasonic flowmeter of the present invention includes, for example, various chemicals and food production lines used in apparatuses for polishing and cleaning silicon wafers in liquid crystal manufacturing processes and liquid crystal manufacturing apparatuses. And liquids such as chemicals used in raw materials, storage and mixing processes in chemical production lines.

  The specific material of the fluororesin measuring line used in the ultrasonic flowmeter of the present invention may be a fluororesin excellent in chemical resistance, heat resistance, weather resistance, transparency, and electrical characteristics. In particular, when PFA (tetrafluoroethylene / perfluoroalkyl / vinyl ether copolymer) is used, not only is the molding property of the measurement pipe line excellent, but the sound speed in the PFA is the sound speed of the fluid to be measured. Therefore, it is more preferable because the ultrasonic beam can be prevented from being transmitted to the measurement pipe and becoming a noise source.

  The specific form of the fluororesin measurement pipe used in the ultrasonic flowmeter of the present invention is, for example, a straight measurement pipe consisting of only a fluororesin measurement pipe through which the fluid to be measured flows. A fluororesin measuring pipe that circulates the fluid to be measured, an inflow pipe that communicates with one end of the fluororesin measuring pipe at a predetermined inflow angle, and the fluororesin measuring pipe Some have a U-shaped measurement pipe configuration including an outflow pipe communicating with a predetermined outflow angle at the other end of the path.

  The specific material of the outer tube made of carbon fiber reinforced resin used in the ultrasonic flowmeter of the present invention is a so-called carbon fiber as a composite material of an epoxy resin as a base material and carbon fiber as a reinforcing material. Any carbon fiber reinforced resin with excellent strength, durability, and heat resistance may be used. Particularly, when a carbon fiber reinforced resin is used, the coefficient of thermal expansion of the carbon fiber reinforced resin outer tube is a fluororesin measuring tube. Since the coefficient of thermal expansion is extremely smaller than the thermal expansion coefficient of the channel, the outer sheath tube made of carbon fiber reinforced resin suppresses changes in the channel cross-sectional area due to the thermal expansion of the fluororesin measurement pipe, and the fluororesin The mechanical rigidity of the measurement pipe line made is increased, and the carbon fiber reinforced resin attenuates the ultrasonic wave repeatedly by irregular reflection by a large number of thin carbon fibers contained in the carbon fiber reinforced resin. Biography Since no carbon fiber reinforced plastic cannula does not propagate ultrasonic vibration directly, further, it is possible to reduce the electrostatic charge to fluorine-based resin measuring tube, and more preferred.

  Furthermore, regarding a specific form of the ultrasonic transmitter / receiver in the ultrasonic flowmeter of the present invention, for example, the measurement direction made of a fluororesin is measured in the thickness direction around the measurement pipe made of fluororesin for circulating the fluid to be measured. The ultrasonic transducers are arranged in a flange shape so as to be parallel to the length direction of the laser beam, and the ultrasonic beam is bent in a substantially orthogonal direction between these ultrasonic transducers and the fluororesin measurement conduit. Ultrasonic transmitter / receiver composed of a beam transmission body provided with a converging concave reflection part and arranged so as to surround the fluororesin measurement pipe, or a fluororesin measurement pipe for circulating the fluid to be measured An ultrasonic transducer that alternately transmits and receives an ultrasonic beam along the central axis of the fluororesin, and one end and the other of the fluororesin measurement pipe that are arranged orthogonal to the central axis of the fluororesin measurement pipe Each at the end Wherein the acoustic impedance matching layer facing the pipe end sealing region made may be an ultrasonic transceiver which is laminated between the vibration absorbing layer facing the ultrasonic transducer.

Below, the ultrasonic flowmeter 100 which is 1st Example of this invention is demonstrated based on FIG. 1 thru | or FIG.
First, as shown in FIG. 1, the ultrasonic flowmeter 100 of the present embodiment is a measurement pipe made of fluororesin made of PFA (tetrafluoroethylene / perfluoroalkyl / vinyl ether copolymer) for flowing the fluid F to be measured. 110 and a fluororesin inflow pipe 120 communicating with the upstream side of the fluororesin measurement pipe 110 at an inflow angle of about 90 degrees and an outflow of about 90 degrees downstream of the fluororesin measurement pipe 110. A fluororesin outflow pipe 130 that communicates at an angle is connected in a U-shape as a whole, and a fluororesin inflow pipe 120 and a fluororesin outflow with respect to the fluororesin measurement conduit 110 in the weighing work area. The installation space with the tube 130 is minimized, and installation interference with other peripheral devices is avoided, and excellent operability is exhibited.
The above-described fluororesin measurement pipe 110, fluororesin inflow pipe 120, and fluororesin outflow pipe 130 are considered in consideration of the smooth fluidity of the fluid F to be measured, the molding process in manufacturing, and the like. Straight pipes are used. Similarly to the fluororesin measuring pipe 110, the fluororesin inflow pipe 120 and the fluororesin outflow pipe 130 are made of PFA (tetrafluoroethylene / perfluoroalkyl / vinyl ether copolymer). .

  In the ultrasonic flowmeter 100 of the present embodiment, ultrasonic transmitters / receivers 140 and 150 are arranged on the upstream side and the downstream side of the fluororesin measurement pipe line 110, respectively. An ultrasonic beam is transmitted from one side into the fluid F to be measured in the measurement pipe 110 made of fluororesin, and is received by the other of the ultrasonic transceivers 140 and 150. Furthermore, the ultrasonic transceiver 140, Measured by fluororesin from the time difference between the time that the ultrasonic beam propagates from the upstream side to the downstream side and the time that the ultrasonic beam propagates from the downstream side to the upstream side by a calculation unit such as a converter (not shown) electrically connected to 150 The velocity of the fluid F to be measured flowing in the conduit 110 is obtained, and the flow rate of the fluid F to be measured flowing in the fluororesin measuring conduit 110 is obtained based on the velocity of the fluid F to be measured. It is.

  In addition, regarding the ultrasonic transmitters / receivers 140 and 150 used in the ultrasonic flowmeter 100 of the present embodiment, the configuration of the ultrasonic transmitter / receiver 140 on the inflow side and the configuration of the ultrasonic transmitter / receiver 150 on the outflow side are the same. The specific configuration of the inflow-side ultrasonic transmitter / receiver 140 will be described, and the specific configuration of the outflow-side ultrasonic transmitter / receiver 150 will be described in the same manner as the members denoted by reference numerals in the 140 series. Therefore, the specific description is omitted.

  As shown in FIGS. 1 and 2, the ultrasonic transmitter / receiver 140 on the inflow side is a disk-shaped ultrasonic wave made of ceramic and enclosed in a pipe portion extending from the upstream side of the measurement pipe 110 made of fluororesin. The vibrator 141, the acoustic impedance matching layer 142 made of glass epoxy resin, the vibration absorbing layer 143 made of silicon rubber, the glycerin layer 144, the cylindrical holding member 146 made of fluororesin, the substrate 147, and rubber O-ring 148 and a lid member 149 for sealing them.

  The disk-shaped ultrasonic transducer 141 is disposed orthogonally to the central axis C of the fluororesin measurement pipe line 110, and is transmitted as an ultrasonic transducer on the transmission side from the substrate 147 via the lead L. An ultrasonic beam is transmitted by vibrating at a resonance frequency by a signal (voltage). On the other hand, the receiving-side ultrasonic transducer is configured to receive and vibrate an ultrasonic beam sent from the transmitting-side ultrasonic transducer and send an electric signal (voltage) to the substrate 147 via the lead L. ing.

The acoustic impedance matching layer 142 faces the pipe end sealing region 111a formed at one end 111 of the fluororesin measurement pipe 110, and is between the pipe end sealing region 111a and the ultrasonic transducer 141. It is arranged.
The acoustic impedance of the acoustic impedance matching layer 142 is set between the acoustic impedance of the duct end sealing region 111a and the acoustic impedance of the ultrasonic transducer 141.

  In short, the acoustic impedance matching layer 142 has the density of the disc-shaped ultrasonic transducer 141 and the end of the pipe so that the ultrasonic beam transmitted from the ultrasonic vibrator 141 is well transmitted to the pipe end sealing region 111a. A thin layer in which small bubbles are mixed in the glass so that the density is intermediate between the density of the sealing region 111a and the density of the acoustic impedance between the ultrasonic transducer 141 and the pipe end sealing region 111a is adjusted. Sudden changes are mitigated.

The vibration absorbing layer 143 is disposed on the side opposite to the acoustic impedance matching layer 142 side in the ultrasonic transducer 141. The vibration absorbing layer 143 has viscoelasticity and is provided to stop vibration early. The vibration absorbing layer 143 also has a role of covering the ultrasonic vibrator 141 and preventing the ultrasonic vibrator 141 from being deteriorated by air or moisture.
The glycerin layer 144 is formed of glycerin applied between the pipe end sealing region 111 a and the acoustic impedance matching layer 142.
The cylindrical holding member 146 holds the substrate 147 therein, and the tip is in contact with the peripheral portion 141a of the disk-shaped ultrasonic transducer 141.

  The O-ring 148 is disposed between the cylindrical holding member 146 and the inner lid member 149. The O-ring 148 is a cushioning material for keeping the pressing force against the disk-shaped ultrasonic transducer 141 at a predetermined magnitude.

Next, as shown in FIG. 3, the fluororesin measurement pipe line 110, which is the most characteristic of the ultrasonic flowmeter 100 of the present embodiment, is in contact with the outer peripheral surface of the fluororesin measurement pipe line 110 in a CFRP state. And a carbon fiber reinforced resin outer cover member 170 is fitted on both ends of the carbon fiber reinforced resin outer tube 160. .
When the outer tube 160 made of carbon fiber reinforced resin is fitted into the measurement pipe 110 made of fluororesin, the outer tube 160 made of carbon fiber reinforced resin has a C-shaped cross section divided into two parts. The fluororesin inflow pipe 120 and the fluororesin outflow pipe 130 projecting from the fluororesin measurement pipe 110 are measured along the longitudinal direction of the fluororesin measurement pipe 110. The pipe parts divided into two parts so as to be sandwiched together with the pipe line 110 are joined and fitted with an adhesive.
As a result, the thermal expansion coefficient of the fluororesin measuring pipe 110 can be affected by the temperature change of the measurement environment and the temperature change of the fluid F to be measured at the time of the flow rate measurement, or the influence of the flow path shape over time. The outer tube 160 made of carbon fiber reinforced resin having a very small size and extremely high mechanical rigidity suppresses a change in the cross-sectional area of the flow channel due to the thermal expansion of the fluororesin measuring tube 110.
Moreover, the outer sheath tube 160 made of carbon fiber reinforced resin does not propagate ultrasonic vibration, and the ultrasonic beam reliably propagates in the measurement pipe 110 made of fluororesin, thereby further improving measurement accuracy.

The fluororesin measurement pipe line 110 is closely fixed to the carbon fiber reinforced resin mantle pipe 160 in a cross-sectional shape formed at a temperature lower than the minimum use temperature of the fluid F to be measured.
Thereby, even if the temperature of the fluid F to be measured at the time of flow rate change to a temperature higher than the minimum operating temperature and the fluororesin measurement pipeline 110 is about to thermally expand, the tensile force higher than that of the fluororesin measurement pipeline 110 is higher. A strong carbon fiber reinforced resin outer tube 160 reliably suppresses the thermal expansion of the fluororesin measurement pipe 110 and keeps the flow path cross-sectional area in the fluororesin measurement pipe 110 constant. .

The outer tube 160 made of carbon fiber reinforced resin is between the upstream side and the downstream side of the fluororesin measurement pipe line 110, that is, between the inflow side ultrasonic transceiver 140 and the outflow side ultrasonic transceiver 150. Are provided over the entire length of the ultrasonic beam propagation region.
As a result, the fluororesin measurement pipe line 110 is not affected by the temperature change of the measurement environment or the temperature change of the fluid F to be measured during flow rate measurement. A predetermined ultrasonic beam propagation path length is secured without expansion and contraction.

In addition, ultrasonic transmitters / receivers 140 and 150 disposed on the upstream side and the downstream side of the fluororesin measurement pipe line 110 are connected to each other by a carbon fiber reinforced resin outer pipe 160.
As a result, the fluororesin measurement pipe line 110 is not affected by the temperature change of the measurement environment, the temperature change of the fluid F to be measured, or the flow path shape over time. Positions such as center lines and parallelism that are likely to be generated between the ultrasonic transmitters / receivers 140, 150, which are securely held without change in the mounting form of the ultrasonic transmitters / receivers 140, 150 that are positioned opposite to each other. Deviation is suppressed.

  The ultrasonic flowmeter 100 of the present example obtained in this manner has a carbon fiber reinforced resin mantle with the fluororesin measuring pipe 110 in close contact with the outer peripheral surface of the fluororesin measuring pipe 110. Since it is fitted to the tube 160, not only the shape of the fluororesin measurement pipe line 110 is stabilized to improve the measurement accuracy, but also the mechanical rigidity of the fluororesin measurement pipe line 110 is increased. Maintaining high-accuracy flow measurement over a long period of time without attaching a temperature sensor or the like to the fluororesin measurement pipe line 110 as in the past, and the fluororesin measurement pipe line 110 is measured Since the cross-sectional shape formed below the minimum operating temperature of the fluid F is tightly fixed to the outer tube 160 made of carbon fiber reinforced resin, the inside of the predetermined measurement tube 110 made of fluororesin that is stably maintained is provided. Based on channel cross-sectional area The flow rate of the measured fluid F flowing through the fluororesin measuring pipe 110 is more accurately obtained, and the flow rate of the measured fluid F is made of a fluorine resin formed at a temperature higher than the minimum operating temperature of the measured fluid F. It is possible to avoid a situation in which the measurement pipe 110 is contracted inside the carbon fiber reinforced resin outer tube 160 and the flow rate of the fluid F to be measured cannot be accurately obtained.

  Further, since the carbon fiber reinforced resin outer tube 160 is provided over the entire length of the ultrasonic beam propagation region between the upstream side and the downstream side of the measurement tube 110 made of fluororesin, this stable predetermined Fluid to be measured flowing in the fluororesin measurement pipe 110 from the time difference between the time of propagation of the ultrasonic beam from the upstream side to the downstream side and the time of propagation from the downstream side to the upstream side based on the ultrasonic beam propagation path length The velocity of F is obtained, and from this velocity of the fluid F to be measured, the flow rate of the fluid F to be measured flowing in the fluororesin measuring pipe 110 can be obtained more accurately.

  Furthermore, since the ultrasonic transmitters / receivers 140 and 150 arranged respectively on the upstream side and the downstream side of the measurement pipe 110 made of fluororesin are connected to each other by the outer tube 160 made of carbon fiber reinforced resin, the temperature change and aging The fluctuation of the ultrasonic propagation beam propagation path and the ultrasonic beam propagation path length due to the influence of the change is prevented to maintain a stable and highly accurate flow rate measurement over a long period of time, and static electricity to the fluororesin measurement pipe line 110 is maintained. In order to reduce the charging, the effects such as the influence on the measurement circuit due to the charging, the destruction of the circuit element, the ignition to the combustible gas, etc. can be easily achieved.

Below, the ultrasonic flowmeter 200 which is 2nd Example of this invention is demonstrated based on FIG. 4 thru | or FIG.
First, as shown in FIG. 4, the ultrasonic flowmeter 200 of this example is a fluororesin measurement pipe made of PFA (tetrafluoroethylene / perfluoroalkyl / vinyl ether copolymer) for flowing the fluid F to be measured. 210 having a straight measurement pipe form composed only of 210, and any one of the installation forms in the measurement area is arranged with either the upstream side or the downstream side facing upward, and inside the measurement pipe 210 made of fluororesin. The bubbles of the fluid to be measured F, which tend to stay in the air, inevitably deaerate, avoiding the bubble obstacle that tends to occur in the measurement pipe 210 made of fluororesin, and transmitting and receiving the ultrasonic beam with high sensitivity. Yes.

  In the ultrasonic flowmeter 200 of this embodiment, ultrasonic transmitters / receivers 240 and 250 are arranged on the upstream side and the downstream side of the fluororesin measurement pipe 210, respectively. An ultrasonic beam is transmitted from one side into the fluid F to be measured in the measurement pipe 210 made of fluororesin, and is received by the other of the ultrasonic transceivers 240 and 250. Furthermore, the ultrasonic transceiver 240, Fluorine-based resin measurement from the time difference between the time that the ultrasonic beam propagates from the upstream side to the downstream side and the time that the ultrasonic beam propagates from the downstream side to the upstream side by an arithmetic unit such as a converter (not shown) that is electrically connected to 250 The velocity of the fluid F to be measured flowing in the pipe 210 is determined, and the flow rate of the fluid F to be measured flowing in the fluororesin measuring pipeline 210 is determined based on the velocity of the fluid F to be measured. It is.

  In addition, regarding the ultrasonic transmitters / receivers 240 and 250 used in the ultrasonic flowmeter 200 of the present embodiment, the configuration of the ultrasonic transmitter / receiver 240 on the inflow side and the configuration of the ultrasonic transmitter / receiver 250 on the outflow side are the same. The configuration of the ultrasonic transmitter / receiver 240 on the inflow side will be described, and a detailed description of the configuration of the ultrasonic transmitter / receiver 250 on the outflow side will be omitted.

As shown in FIG. 4, the ultrasonic transmitter / receiver 240 on the inflow side has a thickness direction around the fluororesin measurement pipeline 210 through which the fluid F to be measured flows, and a length direction of the fluororesin measurement pipeline 210. Ceramic ultrasonic transducers 241, which are also called piezo elements arranged in a flange shape so as to be parallel, and an ultrasonic beam between these ultrasonic transducers 241 and the fluororesin measurement pipe 210 are substantially orthogonal. A beam transmission body 242 provided with a concave reflection portion 242a that bends and converges in a direction so as to surround the measurement pipe 210 made of fluororesin, and a vibration made of silicon rubber provided on the back surface of the ultrasonic transducer 241 And an absorption layer 243.
In addition, the concave reflection part 242a mentioned above can also be made into the concave aspect by a polyhedron as a whole by combining many reflective parts which are planes.

The flange-shaped ultrasonic transducer 241 is arranged orthogonally to the central axis C of the fluororesin measurement pipe line 210 and vibrates at a warp resonance frequency by an electric signal (voltage) as an ultrasonic transducer on the transmission side. Send an ultrasonic beam. On the other hand, as an ultrasonic transducer on the reception side, an ultrasonic beam sent from the ultrasonic transducer on the transmission side is received and vibrated, and an electric signal (voltage) is calculated to a calculation unit that obtains a flow rate through a lead L (not shown). Configured to send.
That is, the ultrasonic beam transmitted by the ultrasonic transducer 241 is focused on one circumference of the fluororesin measurement pipe 210 via the beam transmission body 242, and is emitted into the fluororesin measurement pipe 210. Further, the reached ultrasonic beam enters from one circumference of the fluororesin measuring pipe 210 and is received by the ultrasonic transducer 241 via the beam transmission body 242.

Next, as shown in FIGS. 4 to 5, the fluororesin measurement pipe line 210, which is the most characteristic of the ultrasonic flowmeter 200 of the present embodiment, is in close contact with the outer peripheral surface of the fluororesin measurement pipe line 210. The carbon fiber reinforced resin outer tube 260 is fitted in the state.
As a result, the thermal expansion coefficient of the measurement pipe 210 made of fluororesin is affected by the temperature change of the measurement environment and the temperature change of the fluid F to be measured at the time of the flow rate measurement, or the influence of the flow path shape over time. The outer tube 260 made of carbon fiber reinforced resin having a very small size and extremely high mechanical rigidity suppresses the change in the cross-sectional area of the flow channel due to the thermal expansion of the fluororesin measuring tube 210.
In addition, the outer sheath 260 made of carbon fiber reinforced resin does not propagate ultrasonic vibration, and the ultrasonic beam reliably propagates in the measurement pipe 210 made of fluororesin, thereby further improving the measurement accuracy.

The fluororesin measurement pipe line 210 is closely fixed to the carbon fiber reinforced resin mantle pipe 260 with a cross-sectional shape formed at a temperature lower than the minimum use temperature of the fluid F to be measured.
That is, as a method of tightly fixing the fluororesin measurement pipe 210 and the carbon fiber reinforced resin outer tube 260, the fluororesin measurement pipe 210 is cooled to a temperature lower than the minimum use temperature of the fluid F to be measured. After applying the adhesive, it may be tightly fixed by inserting it into the tube of the carbon fiber reinforced resin outer tube 260.
As a result, even if the temperature of the fluid F to be measured at the time of flow rate measurement is changed to a temperature higher than the minimum operating temperature and the fluororesin measurement pipeline 210 is about to thermally expand, the tensile force higher than that of the fluororesin measurement pipeline 210 is higher. The high strength carbon fiber reinforced resin outer tube 260 reliably suppresses the thermal expansion of the fluororesin measurement pipe 210 and keeps the flow passage cross-sectional area in the fluororesin measurement pipe 210 constant. .

Further, the outer tube 260 made of carbon fiber reinforced resin is disposed between the upstream side and the downstream side of the measurement pipe line 210 made of fluororesin, that is, the ultrasonic transmitter / receiver 240 on the inflow side and the ultrasonic transmitter / receiver 250 on the outflow side. Are provided over the entire length of the ultrasonic beam propagation region.
As a result, the fluororesin measurement pipe line 210 is not affected by the temperature change of the measurement environment or the temperature change of the fluid F to be measured during flow rate measurement. A predetermined ultrasonic beam propagation path length is secured without expansion and contraction.

In addition, the opposed surfaces of the ultrasonic transmitters / receivers 240 and 250 arranged on the upstream side and the downstream side of the fluororesin measurement pipe line 210 are closely fixed to the fluororesin measurement pipe line 210. They are connected to each other by a fiber reinforced resin outer tube 160. A cylindrical tube 280 made of carbon fiber reinforced resin is provided on both outer side surfaces of the ultrasonic transmitters / receivers 240 and 250 via an outer cover member 270 made of carbon fiber reinforced resin, and the ultrasonic transmitter / receivers 240 and 250 and the carbon fiber reinforced resin. The outer tube 260 is surrounded in an encapsulated state, and the outer peripheral portions of the ultrasonic transceivers 240 and 250 are connected to each other.
Accordingly, the provision of the carbon fiber reinforced resin outer tube 260 and the carbon fiber reinforced resin cylindrical tube 270 allows the fluororesin measurement pipe line 210 to measure the temperature change of the measurement environment and the fluid F to be measured during flow rate measurement. Even if it is influenced by temperature changes or the influence of aging of the flow path shape, it is securely held without changing the mounting form of the ultrasonic transceivers 240 and 250 that are positioned opposite to each other. In addition, misalignment such as a center line and parallelism, which tend to occur between the ultrasonic transceivers 240 and 250, and zero point drift are suppressed.

  The ultrasonic flowmeter 200 of the present example obtained in this manner has a carbon fiber reinforced resin sheath with the fluororesin measurement pipe 210 in close contact with the outer peripheral surface of the fluororesin measurement pipe 210. Since it is fitted to the tube 260, not only the shape of the fluororesin measurement pipe line 210 is stabilized to improve the measurement accuracy, but also the mechanical rigidity of the fluororesin measurement pipe line 210 is increased. Maintaining high-precision flow measurement over a long period of time without attaching a temperature sensor or the like to the fluororesin measurement pipe line 210 as in the past, and the fluororesin measurement pipe line 210 is measured Since the cross-sectional shape formed below the minimum operating temperature of the fluid F is tightly fixed to the outer tube 260 made of carbon fiber reinforced resin, the inside of the predetermined measurement tube 210 made of fluororesin that is stably maintained is provided. Based on channel cross-sectional area The flow rate of the fluid F to be measured flowing through the measurement pipe 210 made of fluorine resin is more accurately obtained, and the fluorine resin formed at a temperature higher than the minimum operating temperature of the fluid F to be measured. It is possible to avoid a situation in which the manufactured measuring pipe 210 is contracted inside the carbon fiber reinforced resin outer tube 260 and the flow rate of the fluid F to be measured cannot be accurately obtained.

  In addition, since the outer tube 260 made of carbon fiber reinforced resin is provided over the entire length of the ultrasonic beam propagation region between the upstream side and the downstream side of the measurement pipe 210 made of fluororesin, this stable predetermined Fluid to be measured flowing in the fluororesin measuring pipe 210 from the time difference between the time of propagation from the upstream side to the downstream side of the ultrasonic beam and the time of propagation from the downstream side to the upstream side based on the ultrasonic beam propagation path length The velocity of F is obtained, and the flow rate of the fluid F to be measured flowing through the fluororesin measurement pipe 210 can be obtained more accurately from the velocity of the fluid F to be measured.

  Furthermore, ultrasonic transmitters / receivers 240 and 250 arranged on the upstream side and the downstream side of the fluororesin measurement pipe line 210 are mutually connected by a carbon fiber reinforced resin outer tube 260 and a carbon fiber reinforced resin cylindrical pipe 270. Because it is connected, fluctuations in the ultrasonic propagation beam propagation path and ultrasonic beam propagation path length due to the influence of temperature change and secular change can be prevented, and stable and accurate flow measurement can be maintained over a long period of time. The effect is enormous.

DESCRIPTION OF SYMBOLS 100 ... Ultrasonic flowmeter 110 ... Fluorine-type resin measurement pipe line 111 ... One end 111a ... Pipe end sealing area 112 ... The other end 120 ... Inflow pipe 130 ... · Outflow tube 140 ··· Inflow side ultrasonic transmitter / receiver 141 ··· Ultrasonic transducer 142 ··· Acoustic impedance matching layer 143 ··· Vibration absorbing layer 144 ··· Glycerin layer 146 ··· Holding member 147 ... Substrate 148 ... O-ring 149 ... Inner lid member 150 ... Outflow side ultrasonic transmitter / receiver 160 ... Carbon fiber reinforced resin outer tube 170 ... Carbon fiber reinforced resin outer cover Member 200 ... Ultrasonic flow meter 210 ... Fluorine-based resin measuring pipe 240 ... Inflow side ultrasonic transmitter / receiver 241 ... Ultrasonic vibrator 242 ... Beam transmitter 242a ... Concave reflection portion 243... Vibration absorbing layer 250... Outflow side ultrasonic transmitter / receiver 260... Carbon fiber reinforced resin outer tube 270... Carbon fiber reinforced resin outer cover member 280. Fiber reinforced plastic cylindrical tube F ... Fluid to be measured C ... Center axis L ... Conductor

Claims (4)

An ultrasonic transmitter / receiver is disposed on the upstream side and the downstream side of the fluororesin measurement pipe through which the fluid to be measured flows, and the measurement fluid in the fluororesin measurement pipe from one of the ultrasonic transceivers The fluorine system is transmitted from the other side of the ultrasonic transmitter / receiver and received from the other side of the ultrasonic transmitter / receiver, and from the time difference between the time that the ultrasonic beam propagates from the upstream side to the downstream side and the time that the ultrasonic beam propagates from the downstream side to the upstream side. In the time difference type ultrasonic flowmeter for obtaining the flow rate of the fluid to be measured flowing in the fluororesin measurement pipeline by obtaining the velocity of the fluid to be measured flowing in the resin measurement pipeline,
In order to suppress a change in the cross-sectional area of the flow path due to thermal expansion of the fluororesin measurement pipe, the fluororesin measurement pipe is in close contact with the outer peripheral surface of the fluororesin measurement pipe. An ultrasonic flowmeter that is fitted to a reinforced resin outer tube.   The said fluororesin measuring pipe line is closely fixed with respect to the said carbon fiber reinforced resin mantle pipe in the cross-sectional shape formed below the minimum use temperature of the fluid to be measured. Ultrasonic flow meter.   2. The carbon fiber reinforced resin sheath tube is provided over the entire length of the ultrasonic beam propagation region between the upstream side and the downstream side of the fluororesin measurement pipe line. Or the ultrasonic flowmeter of Claim 2.   The ultrasonic transmitter / receiver respectively disposed on the upstream side and the downstream side of the fluororesin measurement pipe line is connected to each other by the carbon fiber reinforced resin sheath pipe. 4. The ultrasonic flowmeter according to any one of 3.