JPH11108723A - Coriolis mass flow meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy, stability and vibration resistance by providing a vibration tube which makes single vibration or circular motion on a circumference line having a specified distance from each point of a reference axis, the reference axis being set as a straight line connecting an upstream side fixed end with a downstream side fixed end. SOLUTION: A straight line connecting an upstream side fixed end 12 with a downstream side fixed end 13 is set as a reference axis 14, and a vibration tube 11 which makes single vibration or circular motion on a circumference line having a specified radial distance from each point of the reference axis 14 is provided. When a measured fluid is supplied to this vibration tube 11 and an exciter 15 is driven, the center of the vibration tube 11 is repeatedly moved and vibrated on a circumference having a specified radial distance from the reference axis 14. Thus, irrespective of the position of the vibration tube 11, since its length is not changed, a tensile force in an axial direction is made constant, and the leakage of vibration caused by the change of the axial direction force is eliminated. Therefore, since vibration isolation is increased, vibration inside the flow meter is stabilized and Coriolis mass is measured highly accurately and stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Coriolis mass flowmeter which is highly accurate and has improved stability and vibration resistance.

[0002]

2. Description of the Related Art FIG. 24 is an explanatory view of the structure of a conventional example generally used in the prior art.
No. 12 shows a conventional example. In the drawing, reference numeral 1 denotes a vibration tube having both ends attached to a flange 2. The flange 2 is for attaching the vibration tube 1 to the conduit A.

[0003] Reference numeral 3 denotes an exciter provided at the center of the vibration tube 1. Reference numerals 4 and 5 denote vibration detection sensors provided on both sides of the vibration tube 1, respectively. Reference numeral 6 denotes a housing to which both ends of the vibration tube 1 are fixed.

In the above configuration, the measurement fluid is flowed through the vibration tube 1 and the exciter 3 is driven. Assuming that the angular velocity “ω” in the vibration direction of the exciter 3 and the flow velocity “V” of the measurement fluid (hereinafter, a symbol surrounded by “” represents a vector amount),

The mass flow rate can be measured by measuring the amplitude of the vibration proportional to the Coriolis force in which the Coriolis force of Fc = −2 m “ω” × “V” acts.

FIG. 25 is an explanatory view of the configuration of another conventional example generally used conventionally. In this conventional example, the vibration tube 1 is a two-tube type.

[0007]

In a general single straight tube type Coriolis mass flow meter as shown in FIG. 24, the vibrating tube is fixed at both ends, but in a flow meter of a limited size, the end point is fixed. It cannot be completely fixed and will vibrate slightly.

The following causes can be considered as the reason why the vibration occurs. Fig. 2 shows the vibrating tube 1 through which fluid flows.
When the tube is deformed (approximately in a first-order mode resonance state) as shown in FIG. 6, the length of the tube becomes longer due to the deformation, and a tensile stress is generated in the axial direction of the vibrating tube.

For example, φ9.6 × 0.91 of stainless steel
When the center portion of the 400 L vibrating tube 1 is deformed by 1 mm, a tensile force of 7.5 kgf is generated in the axial direction as shown in FIG.

When the vibrating tube 1 is excited in the primary resonance mode, the tensile force is maximized when the plus and minus deformations are maximum, and the tensile force is minimum and zero when the basic shape has no deformation. .

In one cycle of the excitation vibration, the tensile force repeats maximum and minimum twice. That is, the axial pulling force of the vibration tube 1 is generated at twice the frequency of the excitation frequency. The following problems occur when there is vibration due to this pulling force.

If the vibration isolation is insufficient, (1) the Q value becomes low, so that the internal vibration becomes unstable, and it becomes susceptible to extra vibration noise other than the excitation vibration. (2) Large energy is required for excitation, and power consumption increases.

(3) The degree of vibration leakage greatly changes, the vibration state of the vibrating tube also changes, and the zero point and span tend to change due to the installation method, environmental changes such as pipe stress and temperature, and external factors. In other words, Coriolis flowmeters that are unstable with respect to these environmental changes and external factors and have poor vibration resistance and accuracy tend to be poor.

On the other hand, in the conventional example shown in FIG. 25, the two vibrating tubes 1 vibrate in opposite directions, so that the forces cancel each other out at the branch portion, and as shown in FIGS. It has a structure that is hard to leak outside.

However, the structure of one vibration tube having no branch point cannot be obtained.

The present invention solves this problem. An object of the present invention is to provide a Coriolis mass flowmeter which is highly accurate and has improved stability and vibration resistance.

[0017]

In order to achieve the above object, the present invention provides: (1) a measuring fluid flowing in a vibrating tube, and a flow of the measuring fluid and a Coriolis force generated by angular vibration of the vibrating tube; In a Coriolis mass flowmeter that deforms and vibrates the vibrating tube, a simple vibration or a circle is formed on a circumferential line at a predetermined distance from each point of the reference axis with a straight line connecting the upstream fixed end and the downstream fixed end as a reference axis. A Coriolis mass flowmeter comprising a vibrating tube for movement. (2) At least two exciters are formed at a predetermined angle around the reference axis so that the vibrating tube makes a simple vibration or a circular motion, and are arranged in non-contact with the vibrating tube. The Coriolis mass flowmeter according to (1). (3) A rotating body that rotates or rotates with the middle of the vibration tube being locked at a predetermined radial distance from the center axis with the reference axis as the center axis so that the vibration tube makes a simple vibration or circular motion. The Coriolis mass flowmeter according to (1) or (2), further including an excitation device including a driving body that drives the body. (4) The Coriolis mass flowmeter according to (1), (2) or (3), further including a vibrating tube that is curved and arranged at a position where the single vibration or the circular motion is performed in a non-excited state. (5) Applying an excitation component and a predetermined bias component to the vibrating tube at the time of excitation so that the vibrating tube is a straight tube in a non-excited state and is on a circumferential line at a predetermined distance from each point of the reference axis in the excited state. The Coriolis mass flowmeter according to (1), (2) or (3), further comprising: (6) A counterweight connected to the vibration tube is provided at a position opposite to the reference axis so as to prevent the center of gravity of the entire vibration system including the vibration tube and the excitation device from moving during excitation. (1) or (2) or (3) or (4) or (5). (7) A vibration compensator is provided in the vicinity of both fixed ends of the vibration tube along with the vibration of the vibration tube to cancel a rotational component generated around the reference axis and form a node of vibration. 1) or (2) or (3) or (4) or (5) or (6). (8) A rigid body having torsional rigidity connected to both fixed ends of the vibrating tube so that torsional vibration does not leak to the outside, is provided (1) or (2) or (3) or (4). ) Or (5) or (6) or (7). It is what constituted.

[0018]

In the above construction, when the measuring fluid is flowed through the vibrating tube and the exciter is driven, Coriolis force acts.
By measuring the amplitude of the vibration proportional to the Coriolis force, the mass flow rate can be measured.

The vibrating tube uses a straight line connecting the upstream fixed end and the downstream fixed end as a reference axis, and performs a simple vibration or a circular motion on a circumferential line at a predetermined distance from each point of the reference axis. By doing so, vibration isolation from the outside is enhanced. Hereinafter, a detailed description will be given based on embodiments.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention. In the figure, the same symbols as in FIG. 24 represent the same functions. Hereinafter, only differences from FIG. 24 will be described.

Reference numeral 11 designates a straight line connecting the upstream fixed end 12 and the downstream fixed end 13 as a reference axis 14.
Is a vibrating tube that makes a simple vibration or a circular motion on a circumferential line at a predetermined distance from each point.

Reference numeral 15 denotes an exciter provided at the center of the vibration tube 11. 16 and 17 are vibration tubes 11
Are vibration detection sensors provided on both sides.

FIG. 2 is a sectional view taken along line bb of the vibration tube 11 of FIG. 1, FIG. 3 is a sectional view taken along lines aa and cc of the vibration tube 11 of FIG. 1, and FIG. 1
FIG. 4 is a perspective view showing a state of vibration of FIG. 2 and 3, the vibrating tube 11 is in the vicinity of the position A in the non-excited state.

In the excited state, the center of the vibrating tube 11 moves on a circumference separated from the reference axis 14 by a radius R (x). At the position of the cross section bb, the radius R (b)
At the position of the section a-a or cc on the distant circle, the circle at a radius R (a) or R (c) away from the reference axis 14 is A →
Vibrates as B → A → C → A → B → (repeat).

In FIG. 4, A, B and C correspond to the respective positions of the vibrating tube 11 shown in FIGS. In addition, 12, 1
3 indicates a fixed end, and 14 indicates a reference axis.

Since the vibration tube 11 vibrates only in a circumferential plane equidistant from the reference axis 14, the vibration tube 1
No matter where the position 1 is, the length of the vibration tube 11 does not change.

Therefore, the pulling force in the axial direction is always constant. That is, due to the change in the axial force,
Vibration leakage can be eliminated. By increasing the vibration isolation, the vibration inside the flowmeter becomes stable, and a highly accurate and stable Coriolis mass flowmeter can be realized.

More specifically, since the Q value of the internal vibration is increased, it is less susceptible to vibration noise, low power consumption is realized, and a zero point or a span change due to a change in the amount of vibration leakage can be reduced. A mass flow meter is obtained.

As a result, (1) the internal vibration system can realize a high Q value, the influence of external noise is relatively small even if external noise is applied, and the vibration is stable, so that a Coriolis mass flowmeter resistant to external vibration noise can be obtained. Can be

(2) Since stable excitation can be realized with a small amount of energy, a Coriolis mass flowmeter with low current consumption can be obtained.

(3) If the amount of vibration energy dissipated to the outside changes, or if the balance of the amount dissipated upstream and downstream is disturbed, the internal vibration system is affected and the zero point and span fluctuate. In the present invention, since the vibration is always confined inside, there is no need to worry about this, and a highly accurate Coriolis mass flowmeter can be obtained.

(4) If the vibrating tube 11 is previously bent into a predetermined shape in a non-excited state, a Coriolis mass flowmeter having good temperature characteristics can be obtained by absorbing the change in ambient temperature at the curved portion. . Note that a slight change in the curved portion does not affect the output characteristics.

FIG. 5 is a perspective view of a main part of another embodiment of the present invention. A shows the shape of the vibrating tube near the basic position in the non-excited state, and B and C show the shapes of the vibrating tube 11 at the time of maximum deformation.

In the figure, the vibrating tube 11 vibrates in a second mode (or a third or higher vibration mode), and a node of the vibration exists on the reference axis 14.
The vibrating tube 11 vibrates on a circumference separated from the reference axis 14 by R (x).

As for the vibration detection and signal processing, the same processing as that of a normal Coriolis mass flow meter may be performed. For example, the vibration detection sensors 16 and 17 detect the Y component of the vibration, determine the phase difference between the two sensor outputs,
There is a method of obtaining the mass flow rate flowing inside the vibrating tube by adding temperature correction and the like.

FIG. 6 is an explanatory diagram of a main part configuration of another embodiment of the present invention. FIG. 2 shows a cross-sectional view of a vibration tube 11 and an exciter 15. FIG. 3 is a diagram corresponding to FIG. 2. Here, the exciter 15
And three magnetic members 152 attached to the vibrating tube 11. Permanent magnets may be used in combination to increase efficiency.

The exciter 15 generates a force in the direction of arrow D shown in the coil 151 of FIG. In the case of FIG. 6, the three exciters 15 are installed so as to generate forces in directions different from each other by 120 degrees.

In order for the vibrating tube 11 to perform circumferential vibration, the exciting coils 151-1, 151-2, and 151-3 are required.
And the magnetic material 152 generate the following forces. (When the amplitude angle θ of the circumferential vibration is small (θ <π))

Coil 151-1: F1 = Asin (ωt + 0) Coil 151-2: F2 = Bsin (2ωt + π / 2) +
C = Bcos (2ωt) + C coil 151-3: F3 = Asin (ωt + π) = − Asin
(Ωt)

Here, A, B, C: constant ω: angular velocity t: time.

As described above, the magnitude of the force is controlled, and the vibration tube 11 moves on the circumference of the radius R from the reference axis 14.

As a result, (1) a Coriolis mass flow meter capable of realizing in-plane vibration can be obtained by simultaneously using two or more exciters 15 at different angles. (2) By using electromagnetic force, a Coriolis mass flowmeter capable of generating a sufficient force without contact can be obtained.

FIG. 7 is an explanatory diagram of a main part configuration of another embodiment of the present invention. Two excitation coils 151-4, 151-5
Are mounted at different angles by 90 degrees. The exciter 15 generates a force in the direction of arrow D indicated by the excitation coils 151-4 and 151-5.

When the amplitude angle θ is small, the following forces are generated. Coil 151-4: F4 = Asin (ωt + 0) Coil 151-5: F5 = Bsin (2ωt + π / 2) =
Bcos (2ωt)

FIG. 8 is an explanatory perspective view of a main part of another embodiment of the present invention. Reference numeral 21 denotes a center axis of the reference axis 14 such that the vibration tube 11 makes a simple vibration or a circular motion, and a part of the vibration tube 11 is locked at a predetermined radial distance R from the center axis to rotate or rotate. This is an excitation device including a rotating body 211 that drives and a driving body 212 that drives the rotating body 211.

In this case, the reference axis 14
A motor 212 that rotates around the same axis as
Attach 211 to the shaft of motor 212. That disk 2
Reference numeral 11 denotes an inside at a distance of R from the reference axis 14.
Measurement fluid F _LIs connected to the vibrating tube 11 through which the air flows.

When the motor 212 rotates, the vibration tube 11 also moves on a circumference separated from the rotation axis by a radius R. If the rotation of the motor is controlled to rotate, a simple vibration on the circumference is performed as shown in FIGS.

As a result, the rotating or rotating rotator 2
11 and a drive unit 212 for driving the rotating body 211 are provided, so that a Coriolis mass capable of realizing in-plane vibration with a simple mechanical mechanism without using a complicated control circuit. A flow meter is obtained.

If a stepping motor is used, fine control of vibration is possible. A very strong force can be generated depending on the device, and excitation in a non-resonant state is also possible.

FIG. 9 is an explanatory view of a main portion of another embodiment of the present invention, FIG. 10 is an explanatory view of the operation of FIG. 9, and FIG. 11 is a perspective view showing a state of vibration of the vibration tube 11.

Reference numeral 22 denotes a vibrating tube 11 such that the vibrating tube 11 is a straight tube in a non-excited state, and is located on a circumferential line at a predetermined distance from each point of the reference shaft 14 in an excited state.
Is an excitation device that applies an excitation component and a predetermined bias component during excitation.

In the above configuration, in the initial state at the time of non-excitation, the vibration tube 11 exists on the reference shaft 14 as a complete straight tube. In the initial state, the vibration tube 11 exists at the position A in FIG.

When the exciter 22 operates, a bias component of tension is applied, and the exciter 22 moves to a position of a radius R from the reference axis 14. The vibrating tube 11 during excitation is B → C →
Change position like D → C → B → C →.

As a result, the vibrating tube 11 can be completely symmetrical about the reference axis 14 in the Y and Z directions. If the vibration tube 11 has an asymmetric initial shape at the time of non-excitation, the resonance frequency of the vibration in the Y direction and the vibration in the Z direction are slightly different, so that a stable in-plane vibration with a high Q value is realized. Is difficult.

In the present embodiment, the Coriolis mass flowmeter which can realize ideal in-plane vibration at a high Q value can be obtained since the components are completely symmetrical even if they are divided into vibration components in each direction. Further, if the vibration in the Y direction and the vibration in the Z direction are generated completely independently, even if the circumferential in-plane vibration is realized steadily, the torsional component in the axial direction of the vibration tube 11 can be eliminated. it can.

If the torsional component is eliminated, no measures need to be taken for vibration isolation of the component. Since it is axially symmetric, if the amount of vibration is increased, a Coriolis mass flowmeter that can easily realize not only simple vibration but also rotational movement about a reference axis can be obtained.

FIG. 12 is a perspective view of a main part of another embodiment of the present invention, and FIG. 13 is a sectional view taken along the line YZ of FIG. Reference numeral 31 denotes a counterweight connected to the vibration tube 11 at a position opposite to the reference shaft 14 so that the center of gravity of the entire vibration system including the vibration tube 11 and the excitation device 15 does not move during excitation.

In this case, the counterweight 3 is connected to the vicinity of the center of the vibration tube 11 via the connecting arm 32.
1 is set.

In the above configuration, when the vibration tube 11 moves on the circumference in the order of B → A → C, the connecting arm 3
2 and the counterweight 31 move around the reference axis 14 in the order of B ′ → A ′ → C ′ like a pendulum. The counterweight 3 is set so that the center of gravity of the entire vibration system (11, 32, 31) does not change on the reference axis 14.
Determine the position and mass of 1.

As a result, since the center of gravity of the whole vibration system does not move, the whole flowmeter does not generate unnecessary vibration, and the insulation of vibration is further enhanced. By realizing vibration isolation at a higher level, the vibration inside the flow meter becomes more stable, and a highly accurate and stable Coriolis mass flow meter can be obtained.

FIG. 14 is an explanatory view of a main part of another embodiment of the present invention, and FIG. 15 is a sectional view taken along the line YZ of FIG. In the present embodiment, the counterweight 31 and the connecting arm 32
Preparative, those installed in two locations on the upstream side and the downstream side of the vibration tube 11 a measurement fluid F _L flows.

In the above configuration, as shown in FIG.
When the vibration tube 11 moves from B → A → C, the counter mass 31 and the connecting arm 32 move from B ′ → A ′ → C ′.
Move like.

As a result, the vibration tube 11 is
4, the Coriolis mass flowmeter which can easily realize the structure without the movement of the center of gravity can be obtained because it is installed in a place where the torsional vibration is more dominant than the translational vibration.

FIG. 16 is a perspective view of a main part of another embodiment of the present invention, and FIG. 17 is an explanatory view of the operation of FIG. Reference numeral 41 denotes a compensating vibrator that forms a node of vibration by canceling a rotational component generated around a reference axis near both fixed ends of the vibrating tube 11 with the vibration of the vibrating tube 11.

In this case, the compensating vibrator 41 has a disk shape, and the vibrating tube 11 is located near both ends of the vibrating tube 11.
Is combined with The vibration tube 11 has fixed ends 12 and 13
In the vicinity, torsional vibration around the reference axis 14 is the main vibration.

In the above configuration, by attaching the compensating vibrator 41 that rotates in the reverse direction to the torsional rotation,
The vibrations cancel each other, vibration of the vibration tube 11 near the fixed ends 12 and 13 is eliminated, leakage of vibration to the outside is eliminated, and insulation from the outside of the vibration system is achieved.

As a result, the provision of the compensating vibrator 41 can cancel the vibration of the torsional component around the reference axis 14, and does not leak extra vibration to the outside of the Coriolis mass flowmeter. Insulation is further enhanced.

By realizing the vibration isolation at a higher level, the vibration inside the Coriolis mass flowmeter becomes more stable,
A highly accurate and stable Coriolis mass flowmeter can be obtained.

FIG. 18 is an explanatory view of a main portion of another embodiment of the present invention, and is an enlarged view of the vicinity of the upstream fixed end 12. As shown in FIG. This embodiment is an example in which an arm-shaped compensation vibrator 42 is used. As shown in the drawing, a vibrator 43 for forcibly generating a vibration opposite to the torsion of the vibration tube 11 may be provided in the compensation vibration body 42 as necessary.

In the above configuration, the length of the arrow E in FIG. 18 indicates the magnitude of the amplitude. If the compensating vibrator 42 is designed such that the connecting portion between the compensating vibrating body 42 and the vibrating tube 11 becomes a node of the vibration, the compensation vibrating body 42 is fixed to
Thus, a Coriolis mass flowmeter that does not transmit vibration to the vibrating tube 11 over 2 is obtained.

FIG. 19 is an explanatory view of a main part of another embodiment of the present invention, and FIG. 20 is a sectional view taken along line AA of FIG. 51 is
Vibration tube 1 to prevent torsional vibration from leaking to the outside
1 is a rigid body having torsional rigidity connected to both fixed ends.

In this case, a rigid body 51 whose torsional rigidity (torsion stiffness) around the reference shaft 14 is sufficiently larger than that of the vibration tube 11 is attached to the vibration tube 11.

A sufficiently large torsional rigidity means that the rigidity is large by at least one digit. Torsional rigidity of the hollow round shaft = G × π / 32 × ( d 2 4 -d 1 4) G: transverse elastic counting d _2: outer diameter d _1: represented by an inner diameter.

As described above, the torsional rigidity has an effect on the fourth power of the diameter. As shown in FIG. 20, by changing the diameter of the vibration tube 11 and the rigid body 51 having the torsional rigidity, 1 is obtained.
Even a material having rigidity greater than that of a girder can be produced relatively easily.

As a result, the rigid body 5 having sufficiently high torsional rigidity
By having 1, the torsional component of the internal vibration system around the reference axis 14 can be firmly fixed, and the torsional vibration can be prevented from leaking out of the Coriolis mass flowmeter. By realizing vibration isolation at a higher level, the vibration inside the flow meter becomes more stable, and a highly accurate and stable Coriolis mass flow meter can be obtained.

FIG. 21 is an explanatory view of a main part of another embodiment of the present invention, and FIG. 22 is a sectional view taken along the line BB of FIG. In the figure, reference numeral 52 denotes an integrated rigid body 51 having a large torsional rigidity and the housing 6 constituting the detector. The number of parts is reduced, and an inexpensive Coriolis mass flow meter can be obtained.

FIG. 23 is an explanatory view of a main part configuration of another embodiment of the present invention. In the figure, 53 is a rigid body having a large torsional rigidity composed of two rectangular parallelepipeds. Since it does not have a double tube configuration with the vibrating tube 11, a Coriolis mass flowmeter which is easy to manufacture and inexpensive can be obtained.

In the above embodiment, the rigid body 51
Has been described as a cylindrical shape, but is not limited to this, and may be, for example, a rectangular tube shape. In short, any rigid body having a large torsional rigidity connected to both fixed ends of the vibration tube 11 may be used so that the torsional vibration does not leak to the outside.

[0079]

As described above, according to the first aspect of the present invention,
According to (1), the internal vibration system can realize a high Q value, the influence of external noise is relatively small even if added, and the vibration is stable, so that a Coriolis mass flowmeter resistant to external vibration noise can be obtained.

(2) Since stable excitation can be realized with a small amount of energy, a Coriolis mass flowmeter with low current consumption can be obtained.

(3) If the amount of vibration energy dissipated to the outside changes, or if the balance of the amount dissipated upstream and downstream is disrupted, the internal vibration system is affected and the zero point and span fluctuate. In the present invention, since the vibration is always confined inside, there is no need to worry about this, and a highly accurate Coriolis mass flowmeter can be obtained.

According to the second aspect of the present invention, (1) a Coriolis mass flowmeter capable of realizing in-plane vibration can be obtained by simultaneously using two or more exciters while changing the angle. (2) If an electromagnetic force is used, a Coriolis mass flowmeter capable of generating a sufficient force without contact is obtained.

According to the third aspect of the present invention, since the excitation device including the rotating body that rotates or rotates and the driving body that drives the rotating body is provided, a simple control circuit is used without using a complicated control circuit. A Coriolis mass flowmeter capable of achieving in-plane vibration with a mechanical mechanism is obtained.

If a stepping motor is used, fine vibration control can be performed. An extremely strong force can be easily generated, and excitation in a non-resonant state is also possible.

According to the fourth aspect of the present invention, since the vibrating tube is curved into a predetermined shape in a non-excited state,
A Coriolis mass flow meter that can absorb the change in ambient temperature at the curved portion and has good temperature characteristics can be obtained. Note that a slight change in the curved portion does not affect the output characteristics.

According to the fifth aspect of the present invention, a Coriolis mass flowmeter capable of realizing an ideal in-plane vibration with a high Q value is obtained because the symmetry is completely symmetric even when the vibration components in each direction are considered separately. Can be

If the vibration in the Y direction and the vibration in the Z direction are generated completely independently of each other, the torsion component in the axial direction of the vibrating tube can be eliminated even when the vibration in the circumferential plane is constantly realized. be able to.

When the torsional component is eliminated, no measures need to be taken for vibration isolation of the component. Since it is axially symmetric, if the amount of vibration is increased, a Coriolis mass flowmeter that can easily realize not only simple vibration but also rotational movement about a reference axis can be obtained.

According to the sixth aspect of the present invention, since the center of gravity of the whole vibration system does not move, the whole flowmeter does not generate unnecessary vibration, and the vibration isolation is further improved. By realizing vibration isolation at a higher level, the vibration inside the flow meter becomes more stable, and a highly accurate and stable Coriolis mass flow meter can be obtained.

According to the seventh aspect of the present invention, since the compensation vibrator is provided, it is possible to cancel the vibration with respect to the torsional component around the reference axis and to leak extra vibration to the outside of the Coriolis mass flow meter. Is eliminated, and vibration isolation is further enhanced.

By realizing the vibration isolation at a higher level, the vibration inside the Coriolis mass flowmeter becomes more stable,
A highly accurate and stable Coriolis mass flowmeter can be obtained.

According to the eighth aspect of the present invention, by having a rigid body having sufficiently high torsional rigidity, the torsional component around the reference axis of the internal vibration system is firmly fixed, and the outside of the Coriolis mass flow meter is fixed. Leakage of torsional vibration can be prevented. By realizing the vibration isolation to a higher degree, the vibration inside the flowmeter becomes more stable, and a highly accurate and stable Coriolis mass flowmeter flowmeter can be obtained.

Therefore, according to the present invention, it is possible to realize a Coriolis mass flowmeter with high accuracy and improved stability and vibration resistance.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of FIG. 1;

FIG. 3 is an operation explanatory diagram of FIG. 1;

FIG. 4 is an operation explanatory diagram of FIG. 1;

FIG. 5 is a perspective view of a main part of another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 7 is an explanatory view of a main part configuration of another embodiment of the present invention.

FIG. 8 is a perspective view of a main part of another embodiment of the present invention.

FIG. 9 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 10 is an operation explanatory diagram of FIG. 9;

FIG. 11 is an operation explanatory diagram of FIG. 9;

FIG. 12 is a perspective view of a main part of another embodiment of the present invention.

FIG. 13 is a sectional view of FIG.

FIG. 14 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 15 is a side view of FIG. 14;

FIG. 16 is a perspective view of a main part of another embodiment of the present invention.

FIG. 17 is an operation explanatory diagram of FIG. 16;

FIG. 18 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 19 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 20 is a sectional view taken along line AA of FIG. 19;

FIG. 21 is an explanatory view of a main part configuration of another embodiment of the present invention.

FIG. 22 is a sectional view taken along line BB of FIG. 21.

FIG. 23 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 24 is an explanatory diagram of a configuration of a conventional example generally used in the related art.

FIG. 25 is an explanatory view of the configuration of another conventional example generally used in the prior art.

FIG. 26 is an explanatory diagram of the operation in FIG. 24;

FIG. 27 is an explanatory diagram of the operation in FIG. 25;

FIG. 28 is an operation explanatory diagram of FIG. 25;

[Explanation of symbols]

 2 Flange 6 Housing 11 Vibration tube 12 Upstream fixed end 13 Downstream fixed end 14 Reference axis 15 Exciter 151 Excitation coil 152 Magnetic material 16 Vibration detection sensor 17 Vibration detection sensor 21 Exciter 211 Disk 212 Motor 22 Exciter 31 Counter Weight 32 Coupling arm 41 Compensating vibrator 42 Compensating vibrator 43 Exciter 51 Rigid body with torsional rigidity 52 Rigid body with torsional rigidity 53 Rigid body with torsional rigidity

Claims (8)

[Claims] 1. A Coriolis mass flowmeter for deforming and vibrating a vibrating tube by a flow of a measuring fluid flowing in a vibrating tube, and a Coriolis force generated by the flow of the measuring fluid and angular vibration of the vibrating tube. A Coriolis mass flowmeter comprising a vibrating tube that makes a simple vibration or circular motion on a circumferential line at a predetermined distance from each point of the reference axis, with a straight line connecting the downstream fixed end as a reference axis. 2. The apparatus according to claim 1, further comprising at least two excitation devices arranged at a predetermined angle about said reference axis so as to make a single vibration or a circular motion of said vibrating tube, and being arranged in non-contact with said vibrating tube. The Coriolis mass flowmeter according to claim 1, wherein 3. A rotating body having the reference axis as a center axis and a part of the vibration tube being locked at a predetermined radial distance from the center axis so that the vibration tube makes a simple vibration or a circular motion, and is rotated or rotated. 2. An exciter comprising a driving body for driving the rotating body.
Or a Coriolis mass flowmeter according to claim 2. 4. A Coriolis mass flow rate according to claim 1, further comprising a vibrating tube which is previously curved and arranged at a position where said simple vibration or circular movement is performed in a non-excited state. Total. 5. An exciting component and a predetermined bias component when exciting the vibrating tube so that the vibrating tube is a straight tube in a non-excited state and is on a circumferential line at a predetermined distance from each point of the reference axis in the excited state. The Coriolis mass flowmeter according to claim 1, further comprising an excitation device for applying pressure. 6. A counterweight connected to the vibration tube at a position opposite to the reference axis so as to prevent the center of gravity of the entire vibration system including the vibration tube and the excitation device from moving during excitation. Claim 1
A Coriolis mass flowmeter according to claim 2 or claim 3 or claim 4 or claim 5. 7. A vibration compensator for canceling a rotational component generated around the reference axis near both fixed ends of the vibrating tube in accordance with the vibration of the vibrating tube to form a node of vibration. The Coriolis mass flowmeter according to claim 1, claim 2, claim 3, claim 4, claim 5, or claim 6. 8. A rigid body having torsional rigidity connected to both fixed ends of the vibrating tube to prevent torsional vibration from leaking to the outside. Claim 4 or Claim 5 or Claim 6
Or a Coriolis mass flowmeter according to claim 7.