JP5960371B1 - Coriolis mass flow meter - Google Patents

Abstract

To obtain a Coriolis mass flow meter in which a synthetic resin measuring tube is difficult to deform. A reinforcing tube 11b is attached to a U-shaped bent tube portion 11a of a measurement tube 11 made of synthetic resin, and the bent tube portion 11a is held by the reinforcing tube 11b. A first magnetic body holder 11e is attached to the bent tube portion 11a, and a magnetic acting body 11f made of a permanent magnet with a magnetic pole surface facing forward is embedded at the tip. A second magnetic body holder 12a is provided at a separation position facing the tip of the first magnetic body holder 11e, and the magnetic pole surface faces the first magnetic body 11f in the first magnetic body holder 11e so as to face the first magnetic pole surface. A permanent magnet 12b facing the magnetic material holder 11e is disposed, and the magnetic acting surface 11f and the magnetic pole surface of different polarities are opposed to each other. The permanent magnet 12b of the second magnetic body holder 12a attracts the magnetic acting body 11f with a magnetic attraction force, and holds the bent tube portion 11a while being pulled apart and elastically. [Selection] Figure 2

Description

  The present invention relates to a Coriolis mass flow meter that elastically holds the shape of a curved pipe portion.

  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 type 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 allowed to flow through the measurement tube 1, and the vibrator 3 is driven to vibrate the measurement tube 1. 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

  However, in this conventional Coriolis type mass flow meter, even if the measurement pipe 1 is filled with the measurement fluid, the measurement error due to deformation such as the U-shaped curved pipe portion hanging down due to its own weight or the like does not intervene. The measurement tube 1 is usually a metal tube having high rigidity. However, it is difficult to process a metal tube, and it is difficult to prepare metal tubes having the same characteristics by processing. In use, the support structure is large, the weight is increased, and the price is also expensive.

  For this reason, it is conceivable to use a synthetic resin tube for the measurement tube. However, the use of the synthetic resin tube is advantageous in terms of workability and can be reduced in weight. A structure with increased rigidity is required.

  The object of the present invention is to solve the above-mentioned problems, use a measurement tube made of a synthetic resin tube and having a curved pipe part, and to provide a Coriolis mass flow meter that can be reduced in size and is inexpensive and difficult to deform in the curved pipe part. It is to provide.

  A Coriolis type mass flow meter according to the present invention for achieving the above object is a measurement tube made of a synthetic resin having a U-shaped bent tube portion and flowing a measurement fluid from an outward tube to a return tube, Displacement that detects the displacement of the measurement tube at two locations: a holding portion that elastically holds the bent tube portion, an excitation drive unit that applies vibration to the measurement tube, and the forward tube and the return tube of the measurement tube A Coriolis type mass flow meter having a detection unit, wherein the shape of the bent tube portion is retained by a reinforcing member.

  According to the Coriolis type mass flow meter according to the present invention, the shape of the curved pipe portion of the measurement tube made of synthetic resin is held and elastically held, thereby measuring the flow rate based on the generated Coriolis force. It can be realized at low cost.

1 is a perspective view of a Coriolis mass flow meter of Example 1. FIG. 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. 6 is a side view of Example 2. FIG. It is a perspective view of the reinforcement board of one side. 6 is a side view of Example 3. FIG. 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 type mass flow meter of Example 1, 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. The vibration drive unit 13 that vibrates, the displacement detection unit 14 that detects the displacement of the measurement tube 11, the temperature measurement unit 15 that measures the temperature of the measurement fluid, and the detection signals and control signals to these mechanisms are input and output. And a calculation control unit (not shown) for calculating the flow rate of the measurement fluid.

  The measurement tube 11 is made of a synthetic resin tube such as a fluororesin tube, has a diameter of, for example, 3.2 mm, and has a U-shaped bent tube portion 11a at the center, and the bent tube portion 11a includes a metal tube or a synthetic tube. A reinforcing tube 11b made of a resin tube, preferably a metal tube, is attached. 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

  As described above, the bent tube portion 11a covered with the reinforcing tube 11b of the first embodiment is strongly drawn toward the second magnetic material holder 12a. 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.

  In addition, a permanent magnet is attached to the lower side of the first magnetic body holder 11 e as a vibration body 13 a 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 measurement fluid

  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 measurement unit 15 that measures the temperature of the measurement tube 11 is disposed on the substrate 16 below the measurement tube 11. When the measurement tube 11 is heated or cooled depending on the temperature of the measurement fluid, the elastic coefficient changes, and the resonance frequency and the torsional surface of the measurement tube 11 slightly change. To correct these, the measurement tube 11 is corrected. Measure the temperature. If the temperature of the measurement fluid is measured at a location other than the Coriolis type mass flow meter, it is not necessary to measure the temperature using the temperature measurement unit 15.

  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 infrared light with the surface of the measuring tube 11 and the temperature detection element 15b. The temperature detecting element 15b detects infrared rays depending on the surface temperature of the measuring tube 11 through an optical filter (not shown) to obtain the surface temperature. 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.

FIG. 5 is a perspective view of the second embodiment, and FIG. 6 is a perspective view of a reinforcing plate on one side. In addition, the same code | symbol as Example 1 has shown the same member. A magnetic material holder / reinforcing holder 11 e ′ is attached to the bent tube portion 11 a of the measuring tube 11. The magnetic material holder / reinforcing holder 11e ′ is composed of a pair of reinforcing plates 11g and 11h which are made of a synthetic resin material or a metal material and used in an overlapping manner.

  A groove 11i having a semicircular cross section having the same shape as the curved pipe portion 11a is formed on the mating surface of these reinforcing plates 11g and 11h, and the reinforcing plates 11g and 11h are overlapped and fixed to the curved pipe portion 11a from both the upper and lower sides. Then, the curved pipe part 11a is accommodated in the groove part 11i.

In addition, the recessed part 11j is formed in the front end side of the reinforcing plates 11g and 11h, respectively, and the magnetic action body 11f is arrange | positioned in this recessed part 11j. Furthermore, the vibration body 13a that functions as a part of the vibration drive unit 13 is attached to the lower surface of the magnetic material holder / reinforcing holder 11e ', that is, the lower surface of the reinforcing plate 11h, as in the first embodiment. is there.

  With this configuration, the curved tube portion 11a is elastically attracted and held by the magnetic attractive force of the permanent magnet 12b with respect to the magnetic action member 11f, and the vibration driving unit 13 vibrates the measurement tube 11 via the vibration member 13a. This is the same as in the first embodiment. The bent tube portion 11a of the measuring tube 11 is retained by the reinforcing plates 11g and 11h, and the flow rate can be stably measured without deformation of the shape.

  FIG. 7 is a side view of the third embodiment, and the same reference numerals as those in the first and second embodiments indicate the same members. A locking portion 18 is attached to the bent tube portion 11 a that covers the reinforcing tube 11 b, and a holding portion 19 is provided above the locking portion 18. An elastic member 20 made of, for example, a coil spring and pulling the locking portion 18 toward the holding portion 19 is interposed between the locking portion 18 and the holding portion 19.

  Also with this configuration, the bent pipe portion 11a is shaped by being covered with the reinforcing pipe 11b, and deformation of the bent pipe portion 11a is small.

  In addition, although this Example 3 does not use the magnetic attraction force like Example 1, 2, the elastic holding | maintenance with respect to the curved pipe part 11a is made | formed by the elastic member 20. FIG.

  The reinforcing member for the curved pipe portion 11a may be a member other than the reinforcing pipe 11b and the reinforcing plates 11g and 11h of the embodiment.

  In addition, the pulling by the elastic member 20 of the third embodiment may pull a part of the bent tube portion 11a forward by one elastic member, or may be drawn by balancing in the vertical direction using two elastic members. it can.

  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.

11 Measurement tube 11a Curved tube portion 11b Reinforcement tube 11c Forward tube 11d Return tube 11e First magnetic body holder
11e ′ Magnetic body holder / reinforcing holder 11f Magnetic acting body 11g, 11h Reinforcing plate 11i Groove portion 11j Recessed portion 12 Magnetic holding portion 12a Second magnetic body holder 12b Permanent magnet 13 Excitation drive portion 13a Exciting body 13b Electromagnetic coil 14 Displacement Detection unit 14a Light reflection unit 14b Transmitting / receiving unit 15 Temperature measurement unit 15a Lens optical system 15b Temperature detection element 16 Substrate 17 Housing 18 Locking unit 19 Holding unit 20 Elastic member

Claims (6)

  A synthetic resin measuring tube that has a U-shaped bent pipe portion and circulates the measurement fluid in the direction from the forward pipe to the return pipe, a holding portion that elastically holds the bent pipe portion, and a vibration in the measuring tube A Coriolis type mass flow meter having a vibration drive unit for providing a displacement, and a displacement detection unit for detecting displacement of the measurement tube at two locations of the forward tube and the return tube of the measurement tube, A Coriolis type mass flowmeter characterized in that the shape of the cylinder is retained by a reinforcing member.   The Coriolis mass flowmeter according to claim 1, wherein the bent pipe portion is provided at a boundary between the forward pipe and the return pipe.   The Coriolis type mass flow meter according to claim 1 or 2, wherein the reinforcing member is a metal reinforcing pipe attached to the bent pipe portion.   The reinforcing member is a pair of reinforcing plates to which the bent pipe portion is attached, and each of the reinforcing plates has a groove portion having the same shape as the bent pipe portion, and is superimposed on the bent pipe portion from both sides. The Coriolis mass flowmeter according to claim 1 or 2.   The Coriolis mass flowmeter according to any one of claims 1 to 4, wherein the holding portion holds the bent tube portion apart by a magnetic attractive force.   The Coriolis mass flowmeter according to any one of claims 1 to 4, wherein the holding portion holds the bent tube portion with an elastic member.

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