JP7328832B2 - coriolis flow meter - Google Patents

Description

The present invention relates primarily to Coriolis flowmeters attached to evacuated double tubes.

Conventionally, a Coriolis flowmeter is known that vibrates a pipe and calculates the mass flow rate of the fluid based on the Coriolis force generated when the fluid passes through the pipe.

Patent Document 1 discloses a double-tube mounted Coriolis flowmeter comprising a straight support tube and a straight measurement tube arranged therein. This Coriolis flow meter comprises an exciter and two vibration sensors. The exciter is a device for vibrating the measurement tube, and is composed of a permanent magnet fixed to the measurement tube and a coil arranged in a through hole formed in the support tube. By passing an electric current through this coil, the measuring tube can be vibrated via the permanent magnet. The vibration sensor is a device for detecting vibration of the measurement tube, and is composed of a permanent magnet fixed to the measurement tube and a coil arranged in a through hole formed in the support tube. The vibration of the measuring tube can be detected based on the electrical signal generated in the coil based on the vibration of the permanent magnet.

The Coriolis flowmeter of Patent Literature 2 includes two parallel U-shaped flow tubes. The Coriolis flowmeter includes a drive for vibrating the flowtube and a sensor for detecting the vibration of the flowtube. The driving section is composed of a core provided on one flow tube and a drive coil provided on the other flow tube. The sensor consists of a bar magnet provided on one flow tube and a sensing coil provided on the other flow tube.

Japanese Patent Application Laid-Open No. 2001-21402 JP-A-8-338749

Evacuated double tubes are sometimes used, for example, to transport cryogenic fluids. A vacuum double tube suppresses heat input from the outside by creating a vacuum between an inner tube and an outer tube. It is also desired to measure the mass flow rate when a cryogenic fluid is conveyed using a vacuum double tube.

Here, the configuration of Patent Document 1 cannot be applied to a vacuum double tube because a through hole is formed in the support tube. Furthermore, Patent Document 1 discloses only a configuration in which the measurement tube is linear and has one length, and does not describe any application method to other measurement tubes.

Further, in the configuration of Patent Document 2, a drive coil and a sensing coil are attached to one side of the flow tube, and these coils are connected to an electronic device via wiring. Therefore, even if the configuration of Patent Document 2 is applied to the vacuum double tube, heat input to the flow tube occurs through the wiring.

The present invention has been made in view of the above circumstances, and its primary object is to provide a Coriolis flowmeter attached to a vacuum double tube, capable of suppressing heat input to the inner tube for measurement. It is in.

The problems to be solved by the present invention are as described above. Next, the means for solving the problems and the effects thereof will be described.

Aspects of the present invention provide the following Coriolis flowmeter attached to a vacuum double tube. That is, this Coriolis flowmeter includes a first measuring inner tube, a second measuring inner tube, a first driving magnet, a second driving magnet, a driving coil, a first detecting magnet, It comprises a second detection magnet, a first detection coil, a second detection coil, and an arithmetic device. The first inner tube for measurement is a curved tube connected to the inner tube, through which fluid flows. The second inner tube for measurement is connected to the inner tube, is curved in the same direction as the first inner tube for measurement, and has a shape through which fluid flows. The first driving magnet is attached to the first inner tube for measurement or a member that vibrates integrally with the inner tube for measurement. The second driving magnet is attached to the second inner tube for measurement or a member that vibrates integrally with the inner tube for measurement. The driving coil is supported by the outer tube, and the first driving magnet and the second driving magnet are used to move the first inner measuring tube and the second inner measuring tube in a non-contact manner. to vibrate. The first detection magnet is attached to the first measurement inner tube or a member that vibrates integrally with the first measurement inner tube. The second detection magnet is attached to the second inner tube for measurement or a member that vibrates integrally with the inner tube for measurement. The first detection coil is supported by the outer tube, and detects vibration of the first measurement inner tube via the first detection magnet in a non-contact manner. The second detection coil is supported by the outer tube and detects vibration of the second measurement inner tube through the second detection magnet in a non-contact manner. The computing device calculates the mass flow rate of the fluid flowing through the inner tube based on the detection values of the first detection coil and the second detection coil while the drive coil is operating. The drive coil is supported by the outer tube via a coil support provided on the inner wall of the outer tube. The driving coil supported by the outer tube is positioned between the first inner measuring tube and the second inner measuring tube. The driving coil is one coil that vibrates the first driving magnet and the second driving magnet.

Since both the driving coil and the detecting coil which require wiring are supported by the outer tube, the inner measuring tube does not come into contact with the outer tube or members at room temperature. Therefore, heat input to the inner tube for measurement can be suppressed.

ADVANTAGE OF THE INVENTION According to this invention, in the Coriolis flowmeter attached to a vacuum double tube, the structure which can suppress the heat input to an inner tube for a measurement can be provided.

1 is a perspective view showing a state in which a Coriolis flowmeter according to one embodiment of the present invention is attached to a vacuum double tube; FIG. Block diagram of a Coriolis flowmeter. FIG. 4 is a diagram showing the overall configuration of a vibrating section and the internal configuration of a drive coil; FIG. 2 is a cross-sectional view showing the configuration of a detection unit;

Embodiments of the present invention will now be described with reference to the drawings.

A vacuum double pipe 1 shown in FIG. 1 is a pipe for conveying a cryogenic fluid such as liquid hydrogen or liquefied natural gas. The vacuum double tube 1 includes an inner tube 1a and an outer tube 1b. The inner pipe 1a is a pipe for flowing the fluid to be conveyed. The outer tube 1b is arranged so as to cover 360° around the inner tube 1a. The space between the inner tube 1a and the outer tube 1b is hermetically sealed and kept in a vacuum. Since the space between the inner tube 1a and the outer tube 1b serves as a vacuum heat insulating layer, heat input from the outside of the vacuum double tube 1 to the fluid can be suppressed. In the following description, the upstream side and the downstream side in the fluid flow direction are simply referred to as the upstream side and the downstream side.

The Coriolis flowmeter 5 is attached to the vacuum double tube 1 via the branch portion 3 . The branch portion 3 has a branch structure inside. A branch portion 3 on the upstream side of the Coriolis flowmeter 5 divides the fluid flowing through the inner tube 1 a into two and supplies the two to the Coriolis flowmeter 5 . A branch portion 3 on the downstream side of the Coriolis flowmeter 5 combines the fluids flowing through the two pipes of the Coriolis flowmeter 5 into one and supplies it to the inner pipe 1a.

As shown in FIG. 1, the Coriolis flowmeter 5 includes a first measurement inner tube 10, a second measurement inner tube 20, a vibration suppressing plate 30, an excitation section 40, and a detection section 50. .

The first inner tube 10 for measurement includes an upstream linear portion 10a, a curved portion 10b, and a downstream linear portion 10c. The upstream straight portion 10a is a straight pipe portion connected to the branch portion 3 on the upstream side. The curved portion 10b is a pipe portion that is connected to the downstream end of the upstream straight portion 10a and curved in a substantially U shape. Note that the substantially U-shape is merely an example, and the configuration may be curved in other shapes. The downstream straight portion 10c is a straight pipe portion connected to the downstream end of the curved portion 10b and to the branch portion 3 on the downstream side.

The second measurement inner tube 20 includes an upstream straight portion 20a, a curved portion 20b, and a downstream straight portion 20c. The second inner tube 20 for measurement has the same configuration as the first inner tube 10 for measurement, and thus the description thereof is omitted. Although the first inner tube 10 for measurement and the second inner tube 20 for measurement do not have to have exactly the same shape, the curved portion 10b and the curved portion 20b have approximately the same shape, bending direction, and the like. Preferably.

The vibration suppressing plate 30 is provided at the upstream end of the measurement inner tubes 10 and 20 (specifically, the upstream linear sections 10a and 20a) and the downstream end of the measurement inner tubes 10 and 20 (specifically, is a plate-like member that connects the downstream linear portions 10c and 20c). Note that the term "end" is a concept that includes not only the end but also the vicinity thereof. By providing the vibration suppression plate 30, unnecessary vibrations of the measurement inner tubes 10 and 20 can be suppressed. Unwanted vibration means vibration in a direction different from the vibration generated by the vibrating section 40, which will be described later.

Although the vibration suppressing plate 30 of the present embodiment is also attached to and supported by the branch portions 3 on the upstream and downstream sides, even if it is attached and supported only to the inner pipes 10 and 20 for measurement, good. Also, the vibration suppressing plate 30 of the present embodiment is arranged at a position that interferes with the curved portions 10b and 20b. Therefore, the vibration suppressing plate 30 is formed with an opening through which the curved portions 10b and 20b pass. Alternatively, the opening can be omitted by arranging the vibration suppressing plate 30 at a position that does not interfere with the curved portions 10b and 20b. Also, the vibration suppressing plate 30 itself may be omitted.

The vibrating section 40 is arranged in the vicinity of the curved sections 10b and 20b (in the vicinity of the intermediate position in the fluid flow direction). Note that FIG. 1 schematically shows the vibrating section 40 . The vibrating section 40 vibrates the measurement inner tubes 10 and 20 in a non-contact manner. A specific configuration of the vibrating section 40 will be described later.

The detection units 50 are arranged at two locations so as to sandwich the vibrating unit 40 in the fluid flow direction. In addition, in FIG. 1, the detection part 50 is shown typically. The detection unit 50 detects vibration (speed change) of the measurement inner tubes 10 and 20 in a non-contact manner. A specific configuration of the detection unit 50 will be described later.

As shown in FIG. 2 , the Coriolis flowmeter 5 includes an arithmetic device 100 . The computing device 100 includes a drive circuit, an amplifier, and the like for driving the vibrating section 40 and the like included in the Coriolis flowmeter 5 . The arithmetic device 100 also includes an amplifier, an AD converter, an arithmetic unit, and the like for processing the detection value of the detection unit 50 and calculating the mass flow rate (mass of fluid passing per unit time).

Next, details of the vibrator 40 will be described with reference to FIGS. 2 and 3. FIG. FIG. 3 is a cross-sectional view taken along line AA of FIG.

The vibrating section 40 includes a coil support 41 and a drive coil 42 as members on the outer tube 1b side. The coil support 41 is a non-magnetic material. One end of the coil support 41 is attached to the inner wall of the outer tube 1b. A driving coil 42 is attached to the other end of the coil support 41 . The shape of the coil support 41 can be changed as appropriate according to the positions of the inner tubes 10 and 20 for measurement and the drive coil 42 . Alternatively, the coil support 41 may be omitted and the drive coil 42 may be directly connected to the outer tube 1b.

The drive coil 42 is supported (attached) to the outer tube 1b (not to the inner tubes 10 and 20 for measurement) via the coil support 41 . Due to this configuration, the drive coil 42 is independent of the vibrations of the inner measuring tubes 10,20. The drive coil 42 is arranged between the first inner measuring tube 10 and the second inner measuring tube 20 . As shown in FIG. 2, the driving coil 42 is connected to the arithmetic device 100 by wiring, and the driving signal (alternating current) output from the arithmetic device 100 is supplied to the driving coil 42 .

The vibrating section 40 includes magnet supports 14 and 24, a first driving magnet 11, and a second driving magnet 21 as members on the measurement inner tubes 10 and 20 side. The magnet posts 14, 24 are non-magnetic and are connected to the inner tubes 10, 20 for measurement, respectively. The magnet post 14 extends from the first inner measuring tube 10 to approach the second inner measuring tube 20 . The magnet post 24 extends from the second inner measuring tube 20 toward the first inner measuring tube 10 . The magnet supports 14 and 24 are both located inside the driving coil 42 .

A first driving magnet 11 is attached to the end of the magnet column 14 . A second driving magnet 21 is attached to the end of the magnet support 24 . The first driving magnet 11 is arranged on one side with respect to the center of the axial length of the driving coil 42, and the second driving magnet 21 is arranged on the other side. Thus, the driving magnets 11 and 21 are supported (attached) to the inner measuring tubes 10 and 20 via the magnet supports 14 and 24, respectively. With this configuration, the drive magnets 11 and 21 vibrate integrally with the measurement inner tubes 10 and 20 along the axial direction of the drive coil 42 . Also, the magnet supports 14, 24 are covered with yokes 15, 25, respectively. Note that the yokes 15 and 25 may be omitted.

As described above, by supplying the drive signal to the drive coil 42, the measurement inner tubes 10 and 20 can be vibrated via the drive magnets 11 and 21 in a non-contact manner. In addition, the vibrating section 40 vibrates the measurement inner tubes 10 and 20 at their natural frequencies. The measuring inner tubes 10 and 20 vibrate in mutually opposite directions (the phase of the vibration of one is opposite to that of the other). Further, even if the inner tubes 10 and 20 for measurement vibrate or the outer tube 1b vibrates due to external influences, the driving magnets 11 and 21 can continue to be positioned inside the driving coil 42. Moreover, it is preferable that the drive coil 42 is long in the axial direction. Specifically, the axial length of the drive coil 42 is preferably longer than the total vibration range of the drive magnets 11 and 21 caused by the drive coil 42 .

Thus, in the vibrating section 40 of the present embodiment, the drive coil 42 requiring wiring connection is supported by the outer tube 1b instead of the inner tubes 10 and 20 for measurement. Further, the drive coil 42 vibrates the measurement inner tubes 10 and 20 in a non-contact manner. Therefore, the measurement inner tubes 10 and 20 through which the cryogenic fluid flows are not connected to the outside (the outer tube 1b and its outside). Therefore, heat input to the measurement inner tubes 10 and 20 (inner tube 1a) can be suppressed.

Next, details of the detection unit 50 will be described with reference to FIGS. 2 and 4. FIG. FIG. 4 is a cross-sectional view along BB in FIG. As described above, the Coriolis flowmeter 5 includes the two detection units 50. Since these have the same or symmetrical configuration, both will be described together.

The detection unit 50 includes a connecting member 51, a first detection coil 55, a second detection coil 56, and an auxiliary coil 57 as members on the outer tube 1b side.

The connecting member 51 is a non-magnetic material. The connecting member 51 is attached to and supported by the inner wall of the outer tube 1b. In this embodiment, the lower end portion of the connecting member 51 in FIG. 4 is attached to the inner wall of the outer tube 1b, but it may be attached to the inner wall of the outer tube 1b at another position or configuration. The connecting member 51 is formed with openings for allowing the inner tubes 10 and 20 for measurement to pass therethrough. A first mounting portion 52 , a second mounting portion 53 , and a third mounting portion 54 are formed in the connecting member 51 . The connecting member 51 is integrally formed and fixed to the outer tube 1b. Therefore, the mounting portions 52, 53, 54 vibrate integrally with the outer tube 1b.

In a cross section ( FIG. 4 ) taken along a plane perpendicular to the axial direction of the inner measuring tubes 10 and 20 , the first mounting portion 52 is opposite the second inner measuring tube 20 with respect to the first inner measuring tube 10 . located on the side. A first detection coil 55 is attached to the first attachment portion 52 . In this cross section, the second mounting portion 53 is located on the opposite side of the first inner tube 10 for measurement with respect to the second inner tube 20 for measurement. A second detection coil 56 is attached to the second attachment portion 53 . In this cross section, the third mounting portion 54 is located between the first inner measuring tube 10 and the second inner measuring tube 20 . An auxiliary coil 57 is attached to the third attachment portion 54 .

The detection unit 50 includes magnet supports 16, 17, 26, 27, a first detection magnet 12, a second detection magnet 22, and a first auxiliary magnet 13 as members on the measurement inner tubes 10, 20 side. , and a second auxiliary magnet 23 .

The magnet posts 16, 26 are non-magnetic and are connected to the inner measuring tubes 10, 20, respectively. The magnet column 16 extends away from the second inner measuring tube 20 starting from the first inner measuring tube 10 and enters the first detecting coil 55 . A first detection magnet 12 is attached to the tip of the magnet column 16 . The magnet post 26 extends away from the first inner measuring tube 10 starting from the second inner measuring tube 20 and enters the second detecting coil 56 . A second detection magnet 22 is attached to the tip of the magnet support 26 . Note that the detection magnets 12 and 22 may be covered with a yoke, like the drive magnets 11 and 21.

As a result, the first detection magnet 12 vibrates in the first detection coil 55 in accordance with the vibration of the first measurement inner tube 10, so that the current corresponding to the vibration (electric signal for vibration detection, detection value ) occurs. Similarly, since the second detection magnet 22 vibrates in the second detection coil 56 in accordance with the vibration of the second measurement inner tube 20, the current corresponding to the vibration (electric signal for vibration detection, detection value ) occurs. Also, as shown in FIG. 2, the detection coils 55 and 56 are connected to the arithmetic unit 100 by wiring. Electric signals for vibration detection generated by the detection coils 55 and 56 are supplied to the arithmetic unit 100 .

As a method of calculating the mass flow rate of the fluid based on the vibration of the inner tubes 10 and 20 for measurement, a method similar to that of a conventional Coriolis flowmeter can be adopted. Since this method is well known, it will be briefly described below. That is, in a state in which the measurement inner tubes 10 and 20 are vibrated by the vibrating section 40, the fluid flows through the measurement inner tubes 10 and 20, so that the upstream and downstream sides of the curved sections 10b and 20b The direction in which the Coriolis force acts is different. Therefore, a phase shift occurs between the upstream side and the downstream side of the curved portions 10b and 20b. Also, the Coriolis force is correlated with the mass of the object. As described above, the electrical signals generated by the detection coils 55 and 56 of the detection unit 50 on the upstream side and the electrical signals generated by the detection coils 55 and 56 of the detection unit 50 on the downstream side are compared to determine the Coriolis force. By evaluating , it is possible to calculate the total mass flow rate of the fluid flowing through the inner tubes 10 and 20 for measurement (that is, the mass flow rate of the fluid flowing through the inner tube 1a).

Here, for example, when the outer tube 1b vibrates relative to the inner tube 1a due to an external influence, the detection coils 55 and 56 vibrate with respect to the detection magnets 12 and 22 in response to this vibration. . As a result, the accuracy of the calculation result of the mass flow rate of the fluid decreases. In order to reduce this external influence, the detector 50 includes the auxiliary magnets 13 and 23 and the auxiliary coil 57 described above.

The auxiliary magnets 13, 23 are attached to the measuring inner tubes 10, 20 via magnet posts 17, 27, respectively. The magnet posts 17, 27 are non-magnetic and are connected to the measuring inner tubes 10, 20, respectively. The magnet column 17 extends from the first inner tube 10 for measurement toward the second inner tube 20 for measurement and enters the interior of the auxiliary coil 57 . A first auxiliary magnet 13 is attached to the tip of the magnet column 17 . The magnet column 27 extends from the second inner tube 20 for measurement toward the first inner tube 10 for measurement and enters the interior of the auxiliary coil 57 . A second auxiliary magnet 23 is attached to the tip of the magnet column 27 . The first auxiliary magnet 13 is arranged on one side of the center of the axial length of the auxiliary coil 57, and the second auxiliary magnet 23 is arranged on the other side. Incidentally, the auxiliary magnets 13 and 23 may be covered with a yoke like the driving magnets 11 and 21.

Also, the direction of vibration of the detection magnets 12 and 22 and the direction of vibration of the auxiliary magnets 13 and 23 are the same (parallel). Moreover, since both the first detection magnet 12 and the first auxiliary magnet 13 are attached to the first measurement inner tube 10, they vibrate integrally. The same applies to the second detection magnet 22 and the second auxiliary magnet 23 . When the auxiliary magnets 13 and 23 vibrate inside the auxiliary coil 57, a current (auxiliary electrical signal) corresponding to the vibration is generated. As shown in FIG. 2, the auxiliary coil 57 is connected to the computing device 100 by wiring. An electrical signal generated by the auxiliary coil 57 is supplied to the arithmetic device 100 .

The electrical signal generated by the auxiliary coil 57 indicates the direction and magnitude of relative vibration of the outer tube 1b with respect to the inner tube 1a. That is, if the relative vibration of the outer tube 1b with respect to the inner tube 1a does not occur, the auxiliary magnets 13 and 23 only vibrate in opposite directions and symmetrically, so little or no current is generated in the auxiliary coil 57. . On the other hand, when there is relative vibration, the vibration of the auxiliary magnets 13 and 23 further includes an element (component) in which both move integrally in the same direction. Therefore, an electric signal is generated in the auxiliary coil 57 according to the direction and speed in which the auxiliary magnets 13 and 23 vibrate integrally. As described above, the arithmetic unit 100 can calculate the direction and magnitude of the relative vibration of the outer tube 1b with respect to the inner tube 1a based on the electric signal (direction and magnitude of current) of the auxiliary coil 57. FIG.

The arithmetic unit 100 corrects the electric signals of the detection coils 55 and 56 based on the electric signal of the auxiliary coil 57, thereby eliminating the influence of the relative vibration of the outer tube 1b with respect to the inner tube 1a. 10,20 oscillations can be determined. As described above, the computing device 100 can accurately calculate the mass flow rate of the fluid flowing through the inner tube 1a.

Further, in the detection unit 50 of the present embodiment, the detection coils 55 and 56 and the auxiliary coil 57 that require wire connection are supported by the outer tube 1b instead of the inner tubes 10 and 20 for measurement. In addition, these coils can detect vibrations of the measuring inner tubes 10 and 20 in a non-contact manner. Therefore, not only in the vibrating section 40 but also in the detecting section 50, the measurement inner tubes 10 and 20 through which the cryogenic fluid flows are not connected to the outside (the outer tube 1b and its outside). Therefore, the heat input to the measurement inner tubes 10 and 20 (inner tube 1a) can be further suppressed.

As explained above, the Coriolis flowmeter 5 of this embodiment is attached to the vacuum double tube 1 . The Coriolis flowmeter 5 includes a first measuring inner tube 10, a second measuring inner tube 20, a first driving magnet 11, a second driving magnet 21, a driving coil 42, and a first detecting It includes a magnet 12 , a second detection magnet 22 , a first detection coil 55 , a second detection coil 56 , and an arithmetic device 100 . The first measurement inner tube 10 is a curved tube connected to the inner tube 1a, through which fluid flows. The second inner tube for measurement 20 is connected to the inner tube 1a and is curved in the same direction as the first inner tube for measurement 10, through which fluid flows. The first driving magnet 11 is attached to a magnet post 14 that vibrates integrally with the first inner tube 10 for measurement. The second driving magnet 21 is attached to a magnet post 24 that vibrates integrally with the second inner tube 20 for measurement. The drive coil 42 is supported by the outer tube 1b, and the first drive magnet 11 and the second drive magnet 21 are interposed between the drive coil 42 and the first measurement inner tube 10 and the second measurement inner tube 20 in a non-contact manner. to vibrate. The first detection magnet 12 is attached to a magnet post 16 that vibrates integrally with the first inner tube 10 for measurement. The second detection magnet 22 is attached to a magnet post 26 that vibrates integrally with the second inner tube 20 for measurement. The first detection coil 55 is supported by the outer tube 1b and detects the vibration of the first measurement inner tube 10 through the first detection magnet 12 in a non-contact manner. The second detection coil 56 is supported by the outer tube 1b and detects the vibration of the second measurement inner tube 20 via the second detection magnet 22 without contact. The computing device 100 calculates the mass flow rate of the fluid flowing through the inner tube 1a based on the detection values of the first detection coil 55 and the second detection coil 56 while the driving coil 42 is operating.

Since the drive coil 42 and the detection coils 55, 56 which require wiring are both supported by the outer tube 1b, the inner tubes 10, 20 for measurement do not come into contact with the outer tube 1b or members at room temperature. Therefore, heat input to the inner tubes 10 and 20 for measurement can be suppressed.

Also, the Coriolis flowmeter 5 of the above embodiment includes the first auxiliary magnet 13 , the second auxiliary magnet 23 , and the auxiliary coil 57 . The first auxiliary magnet 13 is attached to a magnet post 17 that vibrates integrally with the first inner tube 10 for measurement. The second auxiliary magnet 23 is attached to a magnet post 27 that vibrates integrally with the second inner tube 20 for measurement. The auxiliary coil 57 is supported by the outer tube 1b and produces an auxiliary electric signal based on the vibration of both the first auxiliary magnet 13 and the second auxiliary magnet 23. FIG. The arithmetic unit 100 cancels the influence of the relative vibration of the outer tube 1b with respect to the inner tube 1a from the detection values of the first detection coil 55 and the second detection coil 56 based on the auxiliary electric signal.

This makes it possible to calculate the mass flow rate in consideration of the influence of the relative vibration of the outer tube 1b with respect to the inner tube 1a while preventing contact between the measurement inner tubes 10 and 20 and the outer tube 1b.

Further, in the Coriolis flowmeter 5 of the above embodiment, the first detection coil 55, the second detection coil 56, and the auxiliary coil 57 are supported by the outer tube 1b and vibrate integrally with the outer tube 1b. It is attached to the connecting member 51 .

As a result, since the detection coils 55 and 56 and the auxiliary coil 57 vibrate integrally, the influence of the relative vibration of the outer tube 1b with respect to the inner tube 1a can be removed more reliably.

In the Coriolis flowmeter 5 of the above embodiment, the driving coil 42 is composed of one coil that vibrates the first driving magnet 11 and the second driving magnet 21 .

Thereby, the driving coil 42 can be simplified.

In the Coriolis flowmeter 5 of the above embodiment, the upstream ends in the fluid flow direction of the first inner tube 10 and the second inner tube 20 are connected to the first inner tube 10 and the second inner tube 20, respectively. 2. A vibration suppressing plate 30 is provided that is connected to the downstream end of each of the measurement inner tubes 20 in the fluid flow direction.

Thereby, it is possible to suppress the generation of unnecessary vibrations in the measurement inner tubes 10 and 20 .

Although the preferred embodiments of the present invention have been described above, the above configuration can be modified, for example, as follows.

In the above embodiment, the single drive coil 42 vibrates both the measurement inner tubes 10 and 20 . Instead of this, the drive coil 42 may include two coils, and the two coils may vibrate the measurement inner tubes 10 and 20, respectively.

In the above embodiment, each magnet is attached to the measurement inner tubes 10 and 20 via a rod-shaped magnet post, but each magnet may be attached via a non-bar-shaped member having another shape. Moreover, each magnet may be attached directly to the inner tubes 10 and 20 for measurement.

The vibration suppressing plate 30 is not limited to a plate shape, and may be a thick block shape or a box shape.

Reference Signs List 1 vacuum double tube 5 Coriolis flowmeter 10 first measurement inner tube 11 first drive magnet 12 first detection magnet 13 first auxiliary magnet 20 second measurement inner tube 21 second drive magnet 22 second detection magnet 23 second auxiliary magnet 30 vibration suppressing plate (vibration suppressing portion)
40 excitation unit 41 coil support 42 drive coil 50 detection unit 51 connecting member 55 first detection coil 56 second detection coil 57 auxiliary coil 100 arithmetic unit

Claims (4)

In a Coriolis flowmeter attached to a vacuum double tube having an inner tube and an outer tube,
a first measuring inner tube connected to the inner tube and including a curved portion through which a fluid flows;
a second measuring inner tube connected to the inner tube and including a portion curved in the same direction as the first measuring inner tube through which a fluid flows;
a first driving magnet attached to the first measuring inner tube or a member that vibrates integrally with the first measuring inner tube;
a second driving magnet attached to the second inner tube for measurement or a member that vibrates integrally with the second inner tube for measurement;
A drive coil supported by the outer tube and vibrating the first inner tube for measurement and the second inner tube for measurement via the first magnet for drive and the second magnet for drive in a non-contact manner. and,
a first detection magnet attached to the first measurement inner tube or a member that vibrates integrally with the first measurement inner tube;
a second detection magnet attached to the second inner tube for measurement or a member that vibrates integrally with the second inner tube for measurement;
a first detection coil supported by the outer tube for contactlessly detecting vibration of the first measurement inner tube via the first detection magnet;
a second detection coil supported by the outer tube for contactlessly detecting vibration of the second measurement inner tube via the second detection magnet;
an arithmetic device for calculating the mass flow rate of the fluid flowing through the inner tube based on the detection values of the first detection coil and the second detection coil while the drive coil is operating;
with
The drive coil is supported by the outer tube via a coil support provided on the inner wall of the outer tube,
The drive coil supported by the outer tube is positioned between the first inner tube for measurement and the second inner tube for measurement,
The Coriolis flowmeter, wherein the driving coil is a single coil that vibrates the first driving magnet and the second driving magnet . A Coriolis flowmeter according to claim 1, wherein
a first auxiliary magnet attached to the first inner tube for measurement or a member that vibrates integrally with the first inner tube for measurement;
a second auxiliary magnet attached to the second inner tube for measurement or a member that vibrates integrally with the second inner tube for measurement;
an auxiliary coil supported by the outer tube for producing an auxiliary electrical signal based on vibrations of both the first auxiliary magnet and the second auxiliary magnet;
with
The computing device is characterized in that, based on the auxiliary electric signal, the influence of the relative vibration of the outer tube with respect to the inner tube is canceled from the detection values of the first detection coil and the second detection coil. Coriolis flow meter. A Coriolis flowmeter according to claim 2, wherein
The Coriolis sensor according to claim 1, wherein the first detection coil, the second detection coil, and the auxiliary coil are attached to a connecting member that is supported by the outer tube and vibrates integrally with the outer tube. Flowmeter. Coriolis flowmeter according to any one of claims 1 to 3 ,
The upstream end portions of the first inner tube for measurement and the second inner tube for measurement in the direction of fluid flow are connected to the respective ends of the inner tube for measurement and the second inner tube for measurement in the direction of fluid flow. A Coriolis flowmeter, comprising a vibration suppressor connected to the downstream end of the Coriolis flowmeter.

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