JP6395189B2 - Coriolis mass flow meter - Google Patents

Description

The present invention relates to a Coriolis mass flow meter that measures a flow rate and detects a fluid temperature in a measurement tube from the outside.

  In a semiconductor manufacturing apparatus or the like, for example, a Coriolis type mass flow meter may be used. The Coriolis mass flow meter is a Coriolis force because the Coriolis force acting on the mass point of the mass m that moves toward or away from the rotational center of the rotational vibration system at a velocity V is proportional to the product of the mass m and the velocity V. This is a flow meter of a type that obtains a mass flow rate by measuring.

  Coriolis type mass flowmeters are superior in maintainability compared to differential pressure type, electromagnetic type, positive displacement type flowmeters, because they can directly obtain mass flow rates, have no mechanical moving parts that cause wear, etc. And in principle, it has many excellent features such as the ability to measure the density from the measurement of the frequency of the measuring tube.

  For example, Patent Document 1 discloses a Coriolis mass flow meter using a U-shaped measuring tube as shown in FIG. The measuring tube is composed of a single U-shaped measuring tube 1, and the cantilever-shaped U-shaped measuring tube 1 is vertically moved at a vibrating resonance frequency around a point fixed via mounting flanges 2 a and 2 b. Repeat the vibration. When the measurement fluid that has flowed into the measurement tube 1 flows from the inlet toward the U-shaped bent portion, a Coriolis force is generated due to the velocity with respect to the measurement tube 1, and the measurement tube 1 is distorted and exits from the bent tube portion. When it flows toward, it is distorted in the opposite direction by Coriolis force and becomes a vibration.

  A transducer 3 is provided at the distal end of the U-shape of the measurement tube 1, and displacement detection sensors 4a and 4b are attached to the measurement tube 1 on both sides of the bent portion.

  A measurement fluid is caused to flow through the measurement tube 1, the vibrator 3 is driven, and the measurement tube 1 is vibrated. When the angular velocity ω in the vibration direction of the vibrator 3 and the flow velocity ν of the measurement fluid, the Coriolis force of Fc = −2mω × ν works, and the amplitude of vibration proportional to the Coriolis force Fc is detected by the displacement detection sensors 4a and 4b. If the calculation is performed, the mass flow rate can be measured.

Japanese Patent Laid-Open No. 3-41319

  In this Coriolis type mass flow meter, when the measuring tube 1 is heated or cooled depending on the temperature of the measuring fluid, the elastic coefficient changes, and the resonance frequency and the torsional surface of the measuring tube 1 change slightly and affect the flow rate measurement value. Therefore, it is preferable to measure the temperature of the measurement fluid in order to correct this flow rate measurement value.

An object of the present invention is to measure the flow rate is to provide a measuring tube inside the measuring fluid temperature measuring possible Coriolis mass flowmeter without contacting the measuring tube.

In order to achieve the above object, a Coriolis mass flow meter according to the present invention includes a measuring tube made of a synthetic resin tube that circulates a measuring fluid in one direction, and a magnetic holding device that holds a predetermined position of the measuring tube at a distance. A displacement driving unit that applies vibration to the measurement tube, a displacement detection unit that detects the displacement of the measurement tube at two locations of the forward tube and the return tube of the measurement tube, and an outer side of the measurement tube A Coriolis type mass flow meter having an optical temperature sensing element, wherein the magnetic holding unit causes a magnetic attraction force to act on a magnetic acting member attached to the measurement tube to separate the measurement tube. The measuring tube is transparent or translucent, and includes a lens optical system conjugate of the optical temperature sensing element and the measuring fluid in the measuring tube, and the measuring fluid in the measuring tube is remotely It is characterized by measuring temperature.

According to the Coriolis mass flow meter according to the present invention, it is possible to measure the temperature of the fluid in the measurement tube remotely from the outside of the measurement tube together with the flow rate measurement .

It is a perspective view of the Coriolis type mass flow meter of an example. It is a side view. It is an enlarged block diagram of the principal part. It is a block diagram of a temperature measurement part. It is a perspective view of the Coriolis type mass flow meter of a prior art example.

The present invention will be described in detail based on the embodiment shown in FIGS.
FIG. 1 is a perspective view of a Coriolis mass flow meter of the embodiment, and FIG. 2 is a side view. This Coriolis type mass flow meter mainly includes a measuring tube 11 that circulates a measuring fluid in one direction, a magnetic holding unit 12 that holds a predetermined position of the measuring tube 11 in a separated and elastic manner, and a measuring tube 11. A vibration drive unit 13 that vibrates, a displacement detection unit 14 that detects the displacement of the measurement tube 11, a temperature measurement unit 15 that measures the temperature of the measurement fluid in the measurement tube 11, and a detection signal and a control signal for these mechanisms And a calculation control unit (not shown) for calculating the flow rate of the measurement fluid.

  The measuring tube 11 is made of a transparent or translucent synthetic resin tube, for example, a fluororesin tube, has a diameter of, for example, 3.2 mm, and has a U-shaped bent tube portion 11a at the center. Is attached with a reinforcing tube 11b made of a metal tube or a synthetic resin tube, preferably a metal tube. If the measurement fluid does not have corrosive properties, the measurement tube 11 may be a normal synthetic resin tube instead of a fluororesin tube. However, the measuring tube 11 including the reinforcing tube 11b needs to have an elastic coefficient of hardness that can sufficiently transmit vibration and be not flexible. The diameter of the measuring tube 11 is one example, and it is needless to say that the measuring tube 11 having an arbitrary diameter can be used.

  Thus, by covering the curved pipe part 11a with the reinforcing pipe 11b, even if it is the measurement pipe | tube 11 made from a synthetic resin, there is no possibility that the curved pipe part 11a will deform | transform, and shape retention is possible.

  Two parallel portions of the forward tube 11c and the return tube 11d with the bent tube portion 11a of the measurement tube 11 as a boundary are sandwiched by the housing 17 disposed on the substrate 16, whereby the measurement tube 11 is held. Yes. Therefore, the measurement tube 11 closer to the curved tube portion 11a than these fixed positions is a free end without a mechanical support portion.

  As shown in the enlarged configuration diagram of the main part shown in FIG. 3, a first magnetic body holder 11e made of synthetic resin is added to the reinforcing pipe 11b on the curved pipe section 11a, and a magnetic acting body 11f is provided at the tip. A permanent magnet with the pole face facing forward, or a ferromagnetic material such as iron, cobalt, nickel, or an alloy thereof is embedded.

  A synthetic resin second magnetic body holder 12a of the magnetic holding portion 12 is provided on the substrate 16 at a separation position facing the first magnetic body holder 11e. The magnetic holding unit 12 is connected to the housing 17 holding the measurement tube 11 via the substrate 16, but the substrate 16 may be connected via another member. The second magnetic body holder 12a is made of a strong neodymium magnet or the like so as to face the magnetic action body 11f made of a permanent magnet or a ferromagnetic material in the first magnetic body holder 11e, and the magnetic pole surface is magnetically actuated. A permanent magnet 12b facing the body 11f is arranged. When the magnetic acting body 11f is a permanent magnet, the opposing magnetic poles are different from each other, that is, the S pole and the N pole are opposed to each other. Therefore, the permanent magnet 12b of the second magnetic body holder 12a elastically pulls the magnetic acting body 11f with a magnetic attraction force to separate the bent tube portion 11a of the measuring tube 11 to a predetermined position. It plays the role of the magnetic holding unit 12 that holds the

  Thus, the curved pipe part 11a covered with the reinforcing pipe 11b of the embodiment is strongly drawn toward the second magnetic body holder 12a side. Therefore, even if the measurement fluid flows into the measurement tube 11 in this state, the bent tube portion 11a is elastically held without changing the hanging position due to the weight of the measurement fluid, and the bent tube portion 11a is supported by the reinforcing tube 11b. Is prevented from deforming.

  In addition, in the 2nd magnetic body holder 12a, the magnetic action body 11f can also be attracted | sucked using an electromagnetic coil instead of the permanent magnet 12b. In addition, a magnetic acting body 11f made of a permanent magnet is attached to the first magnetic body holder 11e, and a ferromagnetic body is placed in the second magnetic body holder 12a. It is also possible to apply a magnetic attractive force to the ferromagnetic material of the second magnetic material holder 12a.

  A permanent magnet is attached to the lower side of the first magnetic body holder 11e as a vibration body 13a that functions as a part of the vibration drive unit 13 with the magnetic pole surface facing downward. An electromagnetic coil 13b, which is an electromagnet, is disposed on the substrate 16 below the vibration body 13a, and serves as a vibration driving unit 13 that works in cooperation with the vibration body 13a. In addition to the permanent magnet, the vibrating body 13a may be a ferromagnetic body made of iron, cobalt, nickel, or an alloy thereof.

  The coil 13d wound around the iron core 13c of the electromagnetic coil 13b is energized while switching the direction of the current, and the direction of the magnetic flux generated from the end of the iron core 13c is switched, so that the magnetic attractive force and magnetic repulsion are applied to the vibrating body 13a. A force is applied alternately and repeatedly, and a predetermined vibration is vibrated in a non-contact manner on the measuring tube 11 via the vibrating body 13a and the magnetic body holder 11e.

  This vibration is preferably applied to the symmetrical center position of the measuring tube 11. The vibration frequency is the resonance frequency of the measurement tube 1 in a state where the measurement tube 11 is filled with the measurement fluid, or an integral multiple thereof, and is usually several tens to several hundreds of Hz obtained by auto-tuning. Varies depending on the elastic modulus, shape, and type of fluid being measured.

  Since the amount of vibration by the vibration driving unit 13 is very small, the measurement tube 11 can be vibrated even if the measurement tube 11 is held by the magnetic holding unit 12. In addition, it is also possible to use the vibration drive mechanism other than the electromagnetic coil 13b for the vibration drive part 13. FIG.

  In order to measure the magnitude of displacement caused by the vibration of the measurement tube 11 during flow rate measurement, that is, the Coriolis force, the displacement detection by an optical sensor is provided at two locations of the forward tube 11c and the return tube 11d in the parallel portion of the measurement tube 11. Part 14 is arranged. A light reflecting portion 14a is attached to each of the measuring tubes 11, and a light transmitting / receiving portion 14b is disposed on the substrate 16 below the light reflecting portion 14a.

  In the displacement detector 14, the light beam from the light transmitter / receiver 14b is transmitted toward the light reflector 14a, and the reflected light is received by the transmitter / receiver 14b to detect the positional deviation of the reflected light. Due to this misalignment, the distance from the light transmitting / receiving unit 14b to the light reflecting unit 14a, that is, the distance from each transmitting / receiving unit 14b to the forward tube 11c and the return tube 11d is measured, and the Coriolis in the forward tube 11c and the return tube 11d is measured. An amount corresponding to the amount of twist due to force is obtained by time difference detection in the arithmetic control unit. Then, the flow rate is obtained based on these detected amounts, but since the calculation method and the like are known, the description thereof is omitted.

  The displacement detection unit 14 measures the distance by the positional deviation detection method, but may detect the distance by a blur detection method, an optical interference method, or the like. Further, instead of the light detection method, for example, an electromagnetic displacement detector or the like can be used. However, since the light detection method does not apply force to the measurement tube 11, the flow rate can be measured with high accuracy without affecting the minute Coriolis force.

  A temperature measuring unit 15 that is a fluid temperature measuring device of a flow meter that measures the fluid temperature in the measuring tube 11 from the outside of the measuring tube 11 is disposed on the substrate 16 below the measuring tube 11. FIG. 4 shows a configuration diagram of an infrared radiation thermometer used in the temperature measurement unit 15, and the temperature measurement unit 15 includes a lens optical system 15a and a temperature detection element 15b. The lens optical system 15a conjugates the measurement fluid inside the measuring tube 11 and the optical temperature detection element 15b which is an infrared detection element. Therefore, the infrared rays depending on the temperature of the fluid inside the measuring tube 11 pass through the transparent or translucent measuring tube 11 and detect the temperature via a wavelength selection filter (not shown) arranged in the optical path of the lens optical system 15a. It is detected by the element 15b, and the temperature of the measurement fluid is measured remotely.

  Since this temperature measurement is performed remotely without contacting the measuring tube 11, it does not affect the Coriolis force generated in the measuring tube 11, and can contribute to accurate flow rate measurement. In the embodiment, since this Coriolis mass flowmeter is covered with a cover and the inside is a dark room, ambient ambient light does not become a disturbance in temperature measurement.

  In the embodiment, the measuring tube 11 is arranged horizontally, but it can be arranged in the vertical direction to detect the Coriolis force.

  In addition, the upper and lower sides in this specification are directions with respect to the drawings, and are not necessarily the upper and lower sides in an actual apparatus.

DESCRIPTION OF SYMBOLS 11 Measurement pipe 11a Bending pipe part 11b Reinforcing pipe 11c Forward pipe 11d Return pipe 11e 1st magnetic body holder 11f Magnetic action body 12 Magnetic holding part 12a 2nd magnetic body holder 12b Permanent magnet 13 Excitation drive part 13a Excitation body 13b Electromagnetic coil 14 Displacement detecting unit 14a Light reflecting unit 14b Transmitting / receiving unit 15 Temperature measuring unit 15a Lens optical system 15b Temperature detecting element 16 Substrate 17 Housing

Claims (3)

A measurement tube composed of a synthetic resin tube that circulates the measurement fluid in one direction, a magnetic holding unit that holds a predetermined position of the measurement tube at a distance, an excitation drive unit that applies vibration to the measurement tube, and the measurement A Coriolis type mass flow meter having a displacement detector for detecting the displacement of the measurement tube at two locations of a forward tube and a return tube, and an optical temperature detection element disposed outside the measurement tube, The magnetic holding unit applies a magnetic attraction force to the magnetic action body attached to the measurement tube to hold the measurement tube at a distance, and the measurement tube is transparent or translucent , and the optical temperature A Coriolis mass flow meter comprising a lens optical system that conjugates a sensing element and a measurement fluid in the measurement tube, and remotely measures the temperature of the measurement fluid in the measurement tube . The Coriolis mass flowmeter according to claim 1, wherein the optical temperature detection element is an infrared detection element. The Coriolis mass flowmeter according to claim 1 or 2, wherein a wavelength selection filter is disposed in an optical path of the lens optical system.

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