JP3475786B2 - Coriolis mass flowmeter - Google Patents

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 in which stability, accuracy and vibration resistance are improved by improving the insulation property of internal vibration.

[0002]

2. Description of the Related Art FIG. 46 is an explanatory view of the configuration of a conventional example which is generally used in the past.
This is shown in the conventional example of No. 12. In the figure, a vibrating tube 1 is attached to a flange 2 at both ends. Vibrating tube. The flange 2 is for attaching the vibration tube 1 to the conduit A.

The exciter 3 is provided at the center of the vibrating tube 1. Vibration detection sensors 4 and 5 are vibration tubes 1
Are provided on both sides of. Both ends of the vibrating tube 1 are fixed to the housing 6.

In the above structure, the measuring fluid is flown through the vibrating tube 1 to drive the exciter 3. Assuming that the angular velocity “ω” in the vibration direction of the exciter 3 and the flow velocity “V” of the measurement fluid (hereinafter, the symbol enclosed in “” represents a vector amount).

The mass flow rate can be measured by measuring the amplitude of vibration proportional to the Coriolis force in which the Coriolis force of Fc = -2 m "ω" x "V" acts.

FIG. 47 is a diagram showing the construction of another conventional example which is generally used in the past. In this conventional example, the vibration tube 1 is of a two-tube type.

[0007]

In a general single straight tube type Coriolis mass flowmeter as shown in FIG. 46, a vibrating tube 1 is used.
Although it is fixed at both ends, the end points cannot be fixed completely with a flowmeter of limited size, and it vibrates slightly.

The following causes are considered as the reason why the vibration occurs. When the vibrating tube 1 in which the fluid flows is deformed (approximate first-order mode resonance state) as shown in FIG. 48, the length of the tube becomes longer due to the deformation, so that tensile stress is generated in the axial direction of the vibrating tube. To do.

For example, stainless steel φ9.6 × 0.91
When the central portion of the t, 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 vibration tube 1 is excited in the first-order resonance mode, the tensile force is maximized when the plus and minus deformations are maximum, and the tensile force is zero when the basic shape is not deformed. .

In one cycle of the exciting vibration, the tensile force is repeated maximum and minimum twice. That is, the axial pulling force of the vibrating tube 1 is generated at a frequency twice the excitation frequency. The vibration due to the pulling force causes the following problems.

If the vibration isolation is insufficient, (1) the Q value becomes low, so that the internal vibration becomes unstable, and is easily affected by extra vibration noise other than the excitation vibration. (2) Exciting requires a large amount of energy, which increases power consumption.

(3) Due to the installation method, environmental changes such as piping stress and temperature, and external factors, the degree of vibration leakage also changes greatly, the vibration condition of the vibration tube also changes, and the zero point and span easily change. That is, the Coriolis flowmeter tends to be unstable with respect to these environmental changes and external factors and have poor vibration resistance and accuracy.

On the other hand, in the conventional example shown in FIG. 47, the two vibrating tubes 1 vibrate in mutually opposite directions, so that the forces cancel each other out at the bifurcation, and as shown in FIGS. It has a structure that does not easily leak outside. However, the structure of one vibration tube without a branch point cannot be obtained.

The present invention solves this problem. An object of the present invention is to provide a Coriolis mass flowmeter in which stability, accuracy, and vibration resistance are improved by improving the insulation property of internal vibration.

[0016]

In order to achieve this object, the present invention provides (1) a Coriolis mass flowmeter for deforming and vibrating a vibrating tube by Coriolis force, such as from the upstream fixed end and the downstream fixed end. A straight line which is line-symmetric with respect to the center line of the distance and which has at least one gentle curved portion and which connects the upstream fixed end and the downstream fixed end is used as a reference axis, and each predetermined distance from each point of the reference axis. a single vibration tube to a simple harmonic motion in the circumferential line of the straight to the reference axis or the vibration tube
One end is fixed to this vibration tube and the other end is the reference
A plate-shaped member arranged on the opposite side of the vibration tube with respect to the shaft
The vibrating body, and the mass distribution and shape of the vibrating tube
By adjusting the mass distribution and shape of the vibrating body.
A Coriolis mass flowmeter, wherein a center of gravity of a body is arranged on the reference axis . (2) In a Coriolis mass flowmeter that deforms and vibrates a vibrating tube by Coriolis force, it has at least one gently curved portion that is line-symmetric with respect to the midline equidistant from the upstream fixed end and the downstream fixed end. One vibrating tube that makes a simple vibration on a circumferential line of a predetermined distance from each point of this reference axis with a straight line connecting the upstream fixed end and the downstream fixed end as a reference axis, and the reference axis or the above Direct to vibrating tube
One end is fixed to this vibration tube and the other end is the reference
Is arranged on the opposite side of the vibrating tube to the axis and
At least two plates arranged symmetrically to the center line
A vibrating body, and the mass distribution and shape of the vibrating tube
Adjust the rigidity, mass distribution, shape, rigidity and spacing of the vibrator.
The center of gravity of the whole vibration system at the position of the vibration node of the excited vibration.
It is characterized by being arranged . (3) In a Coriolis mass flowmeter that deforms and vibrates a vibrating tube by Coriolis force, it has at least one gentle curved portion that is line-symmetric with respect to the midline equidistant from the upstream fixed end and the downstream fixed end. One vibrating tube that makes a simple vibration on a circumferential line of a predetermined distance from each point of this reference axis with a straight line connecting the upstream fixed end and the downstream fixed end as a reference axis, and the reference axis or the above Direct to vibrating tube
One end is fixed to this vibration tube and the other end is the reference
Is arranged on the opposite side of the vibrating tube to the axis and
At least two plates arranged symmetrically to the center line
A vibrating body, and the mass distribution and shape of the vibrating tube
Rigidity, mass distribution and shape of the vibrating body, rigidity and spacing
Adjusting both ends of the vibrating tube under steady excitation
The force generated in the
A component perpendicular to the reference axis due to the excitation force of the exciter
It is characterized in that the minute is not generated . (4) It should be orthogonal to the reference axis or the vibration tube.
One end is fixed to this vibration tube and the other end is connected to the reference shaft.
A plate-shaped vibration placed on the opposite side of the vibration tube
The Coriolis mass flowmeter according to any one of claims 1 to 3 , further comprising a body and a vibration detection sensor provided on the other end of the vibrating body . Is configured.

[0017]

In the above structure, when the measuring fluid is flown into the vibrating tube and the exciter is driven, Coriolis force acts.
The mass flow rate can be measured by measuring the amplitude of vibration proportional to the Coriolis force.

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

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the essential parts of an embodiment of the present invention, and FIG. 2 is a side view of FIG. In the figure,
The same symbols as those in FIG. 46 represent the same functions. Only parts different from FIG. 46 will be described below.

The vibrating tube 11 is line-symmetric with respect to the median line 14 equidistant from the upstream fixed end 12 and the downstream fixed end 13 and has at least one gentle curved portion 15. 12 is a reference axis 1 which is a straight line connecting the downstream end 13 and the downstream fixed end 13.
Reference numeral 6 is a single tube that makes a simple vibration on a circumferential line at a predetermined distance from each point on the reference axis 16.

In this case, assuming that the distance between the upstream fixed end 12 and the downstream fixed end 13 is L and the distance between the reference shaft 16 and the vibrating tube 11 is h, approximately h ≦ 0.2.
It is desirable that the shape satisfy L.

The exciter 17 is provided at the center of the vibrating tube 11. The vibration detection sensors 18 and 19 are provided on both sides of the vibration tube 11, respectively.

In the above structure, FIG. 3 is a sectional view taken along the line bb of the vibrating tube 11 shown in FIG. 1, FIG. 4 is a sectional view taken along the line aa, cc of the vibrating tube 11 shown in FIG. 1, and FIG. 1
3 is a perspective view showing a state of vibration of No. 1 of FIG. 2 and 3, in the non-excited state, the vibration tube 11 is near the position A.

In the excited state, the center of the vibrating tube 11 moves on the circumference of a radius R (x) from the reference axis 16. At the position of the cross section b-b, the radius R (b) from the reference axis 16
At the position of the cross-section aa or c-c on the circumference that is distant, A →
It vibrates like B → A → C → A → B → (repeated).

In FIG. 5, A, B and C correspond to respective positions of the vibration tube 11 shown in FIGS. In addition, 12, 1
Reference numeral 3 indicates a fixed end, and 16 indicates a reference axis.

Regarding the vibration detection and the signal processing, the same processing as that of a normal Coriolis mass flowmeter may be performed. For example, the vibration detection sensors 18 and 19 detect the Y component of the vibration, obtain the phase difference between the two sensor outputs, correct the frequency,
By adding temperature compensation, etc., the mass flow rate inside the tube can be calculated.

Since the vibration tube 11 vibrates only within the circumferential surface equidistant from the reference axis 16, the vibration tube 1
No matter where the position of 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 axial force,
Vibration leakage can be eliminated. By increasing the vibration isolation, the vibration inside the flow meter becomes stable, and a highly accurate and stable Coriolis mass flow meter can be realized.

Specifically, since the Q value of the internal vibration is high, it is less likely to be affected by vibration noise, low power consumption is realized, and the zero point and span change due to the change in the amount of vibration leakage can be reduced. A mass flow meter is obtained. By enhancing the vibration isolation in this way, the following advantages are exhibited.

As a result, (1) the internal vibration system can realize a high Q value, the influence of external noise is relatively small, and the vibration is stable, so that a Coriolis mass flowmeter resistant to external vibration noise can be obtained. To 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 dissipation of vibration energy to the outside changes or the balance of the amount of dissipation is lost in the upstream and downstream, the internal vibration system is affected and the zero point and span fluctuate. In the present invention, since the vibration is always trapped inside, the Coriolis mass flowmeter with high accuracy can be obtained without the concern.

(4) Since the measurement fluid FL _o channel has a single penetrating structure with no branch or gap from the inlet (inlet) to the outlet (outlet) of the flowmeter, the flow velocity loss is small. ,
A Coriolis mass flowmeter that is less likely to clog and easy to clean is obtained.

(5) Vibration tube 1 rather than a perfect straight tube
Since No. 1 is bent 15 into a predetermined shape in a non-excited state, the Coriolis mass flowmeter having good temperature characteristics can be easily absorbed by the bent portion 15 against ambient temperature changes.

A Coriolis mass flowmeter which can realize the advantages of a curved pipe and a straight pipe at the same time can be obtained by having an appropriate curve, not a general curved pipe or a complete straight pipe.

FIG. 6 is an explanatory view of the essential parts of another embodiment of the present invention, which is an embodiment of claim 2. Plate-shaped vibrator 21,
Reference numeral 22 is orthogonal to the reference shaft 16 or the vibration tube 11, and in this case, is orthogonal to the reference shaft 16 and has one end fixed to the vibration tube 11 and the other end with respect to the reference shaft 16 and the vibration tube 11. It is located on the opposite side. However, in this case, two pieces are arranged at positions symmetrical with respect to the center line 14.

As shown in FIG. 6, the vibration system has a line-symmetrical shape with respect to the X-axis direction. That is, the vibrating tube 11, the vibration detection sensors 18 and 19, and the vibrating bodies 21 and 22 are located at symmetrical positions with respect to the midline 14 (axisymmetrical reference axis) between the upstream fixed end 12 and the downstream fixed end 13. Exists.

At this time, the mass distribution and shape of the vibrating bodies 21 and 22 are adjusted so that the entire vibrating system (the vibrating tube 11, the vibration detecting sensors 18 and 19, the exciter 17, the vibrating body 21,
The center of gravity of 22) is arranged on the reference axis 16.

That is, if the shapes and weights of the vibration tube 11, the vibration detection sensors 18, 19 and the exciter 17 are determined, the total mass M and the center of gravity (Z: Z coordinate of the center of gravity) of them are determined.

Adjusting the mass and shape of the vibrators 21 and 22,
When the total mass m and the center of gravity position z are satisfied, the center of gravity of the entire vibration system is arranged on the reference axis 16 when the relationship of M × Z = m × z is established.

As a result, the center of gravity of the entire vibration system is the reference axis 16.
Since it is on the upper side, even when vibration noise is applied from the outside or a shock is applied, abnormal operation is unlikely to occur, such as abnormal vibration of a portion away from the center of gravity.

Further, even when it is affected, it is symmetrical in the whole vibration system and relatively easily affected. Even if it is not normal vibration, vibrations at two points upstream and downstream of the vibration tube 11 are detected. This makes it possible to cancel noise.

From the above, it is possible to obtain a stable and highly accurate Coriolis mass flowmeter which is hardly affected by external vibration or shock.

FIG. 7, FIG. 8, FIG. 9 and FIG. 10 are explanatory views of the essential structure of another embodiment of the present invention. In the vibration operation explanatory view of claim 3, a modal analysis result of the finite element method using the beam element is shown.

7 is a perspective view, FIG. 8 is a projection view from the X direction of FIG. 7, FIG. 9 is a projection view from the Y direction of FIG. 7, and FIG. 10 is a projection view from the Z direction of FIG. Shape D in the initial state,
Both shapes E at maximum deformation are shown.

The vibrating tube 11 and the vibrating bodies 21 and 22 are
As shown by the arrow F in FIGS. 7, 8, 9 and 10, the deformation is performed from the initial state position D to the maximum positive deformation position E, and returns to the initial position D again, and the maximum positive deformations E and XY. It becomes a maximum negative deformation E symmetrical with respect to the plane, and returns to the initial position D.

The vibration system repeats such simple vibration.
Note that this analysis is a linear analysis when the deformation amount is small, and the actual deformation amount is shown in an enlarged manner for easy understanding in FIGS. 7, 8, 9, and 10.

In the third aspect, the mass distribution, the shape and the rigidity of the vibrating tube 11, the mass distribution, the shape, the rigidity and the interval of the vibrating bodies 21, 22 are adjusted to adjust the entire vibrating system (the vibrating tube 11 and the vibrating tube 11). , Vibration detection sensors 18 and 19, and exciter 1
7 and the position of the center of gravity of the vibrating body 21, 22),
(See FIG. 8) It is characterized by being installed above. The basic configuration explanatory diagram is similar to that of FIG.

At the position of vibration node G, the vibration system generates a rotation component around the X axis, but the position does not move (X, Y,
Z coordinate does not change). When the shape of the vibrating tube 11 is predetermined, the center of gravity of the entire vibrating system can be arranged on the vibration node G by adjusting the weight of the vibrating bodies 21 and 22.

It should be noted that the position of the vibration node G is determined by the vibrating body 21,
It is largely dependent on the mounting position of 22. Generally, according to the center (or aggregated into one center),
1, FIG. 12, FIG. 13, and FIG. 14, the vibration node G is Y
It is the positive direction of the axis.

Incidentally, FIGS. 11, 12, 13, and 14.
Shows the modal analysis results of the finite element method using beam elements.

FIG. 11 is a perspective view, FIG. 12 is a projection view from the X direction of FIG. 11, FIG. 13 is a projection view from the Y direction of FIG. 11,
FIG. 14 is a projection view from the Z direction in FIG. 11, and shows both the shape D in the initial state and the shape E at the maximum deformation.

As shown in FIG. 15, FIG. 16, FIG. 17, and FIG. 18, if the value is adjusted to an appropriate value, the vibration node G on the reference shaft 16 is generated.
Can be arranged. Note that FIG. 15, FIG.
17 and 18 show modal analysis results of the finite element method using beam elements.

FIG. 15 is a perspective view, FIG. 16 is a projection view from the X direction of FIG. 15, FIG. 17 is a projection view from the Y direction of FIG.
FIG. 18 is a projection view from the Z direction in FIG. 15, and shows both the shape D in the initial state and the shape E at the time of maximum deformation.

The vibration tube 11 and the vibrating body 21,
In addition to the large Y coordinate of the connection point of 22, the vibrating tube 11 has a large deformation angle around the reference axis 16 near the central portion, and the vibrating bodies 21 and 22 connected thereto also have a large angle. It is considered that the intersection between the bodies 21 and 22 and the Y axis is in the positive direction of the Y axis.

For the above reasons, in order to install the center of gravity on the reference axis 16 and on the vibration node G, it is necessary to provide one vibrating body at the center, which satisfies the purpose. I can't. Two vibrating bodies 21 and 22 which are symmetrical in the upstream and downstream directions are required.

As a result, since the center of gravity of the entire vibration system does not move, useless vibration is eliminated and vibration isolation is further enhanced. By increasing the vibration isolation in this way, the following advantages are obtained.

(1) The internal vibration system can realize a high Q value, and even if external noise is applied, its influence is relatively small 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 dissipation of vibration energy to the outside changes or if the balance of the amount of dissipation is lost in the upstream and downstream of the vibrating tube 11, the internal vibration system is affected and the zero point and span fluctuate. Resulting in.

In the present invention, since the vibration is always trapped inside, there is no fear of this, and a highly accurate Coriolis mass flowmeter can be obtained.

(4) Even if a translational noise or shock, which is normally received from the outside, is applied and the center of gravity moves in translation, the motion is different from the normal excitation vibration. Can be easily distinguished.

It is possible to obtain a stable and highly accurate Coriolis mass flowmeter which is hardly affected by external vibration or shock.

19, FIG. 20, FIG. 21, and FIG. 22 are explanatory views of the essential parts of another embodiment of the present invention, and are explanatory views of the vibrating operation of claim 4. The modal analysis results of the finite element method using shell elements are shown. The basic configuration diagram is the same as that shown in FIG.

FIG. 19 is a perspective view, FIG. 20 is a projection view from the X direction of FIG. 19, FIG. 21 is a projection view from the Y direction of FIG.
FIG. 22 is a projection view from the Z direction in FIG. 19, and shows both the shape D in the initial state and the shape E at the time of maximum deformation.

The vibrating tube 11 and the vibrating bodies 21 and 22 are
As shown by the arrow F in the figure, simple vibration is repeated around the initial position D up to the positive and negative maximum deformation positions. Note that FIG.
9, FIG. 20, FIG. 21, and FIG. 22, the deformation amount is shown in an enlarged manner for easy viewing.

The mass distribution, shape and rigidity of the vibrating tube 11 and the mass distribution, shape, rigidity and spacing of the vibrating bodies 21, 22 are adjusted to fix both end fixing portions 12, 13 of the vibrating tube 11 in the steady excitation state. Is a device in which only the twisting component ROTX around the reference axis 16 is generated as a force generated in the reference axis 16 and the components FY and FZ orthogonal to the reference axis 16 due to the excitation force by the exciter 17 are not generated.

23 and 24 show a calculation model that realizes the fourth aspect. FIG. 23 is a front view from the Z direction, and FIG.
Is a perspective view. When stainless steel is used and the dimensions are as shown in FIGS. 23 and 24, the total Z-direction force applied to the fixing portions 12 and 13 at both ends is

When M = 32 g, ΣFZ≈0.4 kgf M = 33 g, ΣFZ≈0.13 kgf M = 33.5 g, and ΣFZ≈0 kgf At this time, the force applied to the fixed ends 12 and 13 at both ends was almost eliminated.

As a result, in the steady excitation state, the force F of the translational direction component other than the twist component ROTX about the reference axis 16 is applied to the fixed portions 12 and 13 at both ends of the vibration tube 11.
Since Y and FZ do not occur, it is difficult for vibration to leak to the outside.

Coriolis mass flow rate having much higher torsional rigidity (torsional rigidity = G Ip = Gπd4 / 32 rigidity is the 4th power of the diameter) than the vibration tube 11 with respect to the rotational force around the reference axis 16. The presence of the meter housing 6 makes it possible to hold it down firmly.

By enhancing the vibration isolation in this way, the following advantages can be obtained. (1) The internal vibration system can realize a high Q value, the influence of external noise is relatively small, 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 dissipation of vibration energy to the outside changes, or if the balance of the amount of dissipation is lost in the upstream and downstream of the vibrating tube 11, the internal vibration system is affected and the zero point and span fluctuate. Resulting in. In the present invention, since the vibration is always trapped inside, the Coriolis mass flowmeter with high accuracy can be obtained without the concern.

FIG. 25 is an explanatory view of the essential parts of another embodiment of the present invention, which is an embodiment of claim 5. Vibration sensor 1
8 and 19 are provided at the other ends of the vibrating bodies 21 and 22.

The vibration detecting sensors 18 and 19 are attached to the reference shaft 16
Vibrating body 2 in the opposite direction from the vibrating tube 11
By installing near the tips of 1 and 22, vibration can be detected at the optimum position.

By being located at the tips of the vibrating bodies 21 and 22, it becomes possible to measure the vibration at a place having the largest amplitude in the vibrating system. Moreover, the phase difference generated by the Coriolis force also becomes very large.

Actually, as a result of comparison between the embodiment of FIG. 6 and the embodiment of FIG. 25 (corresponding to claim 6) by an experiment, the following is obtained as an example. The ratio of sensor amplitude / drive amplitude is shown in FIG.
The example is 0.8, and the example in FIG. 25 is 3.5. Generated phase difference
<m rad> is 8.8 in FIG. 6 embodiment and 37.5 in FIG. 25 embodiment. Becomes

As described above, both the amplitude ratio and the generated phase difference were observed to be slightly more than four times as large as in the case of the embodiment of FIG.

As a result, (1) The S / N is improved if the measured amplitude is large. On the contrary, if the measurement amplitude is comparable to the conventional one, the excitation force can be reduced and a Coriolis mass flowmeter with low power consumption can be obtained. If the maximum amplitude is small, the vibration energy is small, the leakage to the outside is small, the vibration insulation is easy, and a highly accurate and stable Coriolis mass flowmeter can be obtained.

(2) If the generated phase difference is large, the signal processing of the signal conversion portion becomes easy. That is, it is possible to obtain a Coriolis mass flowmeter that can realize stable and highly accurate performance even with a simple and inexpensive signal processing circuit.

On the contrary, if the signal processing performance is equivalent to that of the conventional one, stable measurement is possible even in the low flow rate region where the generated phase difference is small, and the mass flow rate measurement of gas having a small generated phase difference is originally possible. A possible Coriolis mass flow meter is obtained.

After all, since the amplitude and the phase difference are four times or more larger, it is very advantageous and a dramatic improvement effect can be obtained.

FIGS. 26, 27, 28, and 29 are explanatory views of the essential part of another embodiment of the present invention. FIG. 26 is an explanatory view of the vibration operation of claim 6, in which the vibration tube 11 is moved by the exciter 17. Two
Excitation is performed in higher-order vibration modes higher than the next mode. 25 is a result of performing modal analysis by the finite element method using the shell element in the example of FIG.

FIG. 26 is a perspective view, FIG. 27 is a projection view from the X direction of FIG. 26, FIG. 28 is a projection view from the Y direction of FIG.
FIG. 29 is a projection view from the Z direction in FIG. 26, and shows both the shape D in the initial state and the shape E at the time of maximum deformation.

In the third mode resonance state of the embodiment of FIG. 25, the resonance frequency is 267 Hz. Normally, when self-excited, the lowest vibration mode is likely to be excited, but in this embodiment,
The exciter 17 is adjusted so that the third mode is excited, and self-excited.

The first-mode resonance frequency in the embodiment of FIG. 25 is 153 Hz, which is the vibration mode shape as shown in FIGS. 30, 31, 32, and 33.

FIG. 30 is a perspective view, FIG. 31 is a projection view from the X direction of FIG. 30, FIG. 32 is a projection view from the Y direction of FIG. 30,
FIG. 33 is a projection view from the Z direction in FIG. 30, and shows both the shape D in the initial state and the shape E at the time of maximum deformation.

In FIGS. 30, 31, 32, and 33,
The entire vibration system is deformed in the + Z direction. Since it is not a circumferential vibration, and the excitation force is directly applied to the ends 12 and 13,
A large force is applied to the ends 12 and 13 in the X and Z directions.

In the embodiment of FIG. 25, the resonance frequency of the secondary mode is 250 Hz, which is the vibration mode shape as shown in FIGS. 34, 35, 36 and 37.

34 is a perspective view, FIG. 35 is a projection view from the X direction of FIG. 34, FIG. 36 is a projection view from the Y direction of FIG. 34,
FIG. 37 is a projection view from the Z direction in FIG. 34, and shows both the shape D in the initial state and the shape E at the time of maximum deformation.

34, 35, 36 and 37,
In the vibrating tube 11, the deformation in the Z direction is reversed in the plus and minus directions near the center thereof. Since the amount of deformation of the vibration tube 11 itself is small, the Coriolis force is also small,
It is not a practical vibration mode.

In the embodiment of FIG. 25, the fourth-order mode resonance frequency is 397 Hz, which is the vibration mode shape as shown in FIGS. 38, 39, 40 and 41.

38 is a perspective view, FIG. 39 is a projection view from the X direction of FIG. 38, FIG. 40 is a projection view from the Y direction of FIG. 38,
FIG. 41 is a projection view from the Z direction in FIG. 38, and shows both the shape D in the initial state and the shape E at the time of maximum deformation.

38, 39, 40, and 41, the shape is complicated but the resonance frequency is high.
It does not have a bad effect.

As a result, the following advantages are obtained by exciting in the second, third, or higher order modes. (1) It is easy to set the excitation frequency higher. Vibration at low frequencies is susceptible to field vibration noise, while high frequency excitation provides a Coriolis mass flowmeter that is less susceptible to vibration noise.

(2) The resonance frequencies of the excitation mode and the vibration mode generated by the Coriolis force can be brought close to each other. In the embodiment of FIG. 25, the drive frequency is 260 Hz, and the Coriolis approximation mode is close to 246 Hz.

From the following equation, since P = 1.057 and Q = 1000, the dynamic magnification becomes large at G = 8.5 and the generated phase difference is large. However, the dynamic magnification ^{G = (1-P 2)} / ((1-P 2) 2 + (P / Q)) P = ( drive frequency) / (the resonant frequency of the Coriolis approximation mode)

(3) If the generated phase difference is large, the signal processing of the signal converter becomes easy. That is, it is possible to obtain a Coriolis mass flowmeter that can realize stable and highly accurate performance even with a simple and inexpensive signal processing circuit.

On the other hand, if the signal processing performance is equivalent to that of the conventional one, stable measurement is possible up to a low flow rate range where the generated phase difference is small, and the mass flow rate measurement of gas having a small generated phase difference is originally possible. A possible Coriolis mass flow meter is obtained.

42, 43 and 44 are explanatory views of the essential parts of another embodiment of the present invention, which is an embodiment of claim 7. 42 is a front view, FIG. 43 is a plan view of FIG. 42, and FIG.
FIG. 43 is a side view of FIG. 42.

The compensator 31 is provided inside the housing 61. Inside the compensator 31, the vibration tube 11
, The exciter 17, and the vibration detection sensors 18 and 19 are installed.

In this case, an example in which coils 171, 181, 191 and magnets 172, 182, 192 are used for the exciter 17 and the vibration detection sensors 18, 19 is shown. The compensator 31 is provided parallel to the reference axis 9,
It is long in the parallel direction, and both ends thereof are fixedly supported at both ends of the vibration tube 11.

With the above structure, as shown in FIG.
When the exciter 17 is operating, the coil 171 and the magnet 172 are repelled by the force of F ₁ and F ₂ . By that power,
The vibrating tube 11 and the vibrating bodies 21 and 22 rotate in the clockwise direction in FIG. 44 around the reference axis as in T _{1 and} T ₃ .

On the other hand, the compensator 31 has T ₂ and T _{4 due to} its reaction force.
As described above, the vibrating tube 11 and the vibrating bodies 21 and 22 rotate counterclockwise, which is a counterclockwise direction.

Since the vibrating tube 11 and the compensator 31 are connected to each other, the fixed ends 12 and 13 which are the connecting portions are
The clockwise force and the counterclockwise force cancel each other out, which has the effect of reducing such an axial component. Outside the compensator 31
The rotation component around the reference axis 16 can be prevented from leaking.

As a result, since the compensator 31 is installed in the housing 6, the vibrating tube 11, the vibrating bodies 21, 2 are arranged.
2, the vibration detection sensors 18 and 19 and the compensator 31 exert forces in opposite directions via the exciter 17, and the reference shaft 16
Vibration of the reverse rotation centering on is generated.

At the fixed ends 12 and 13 where the vibrating tube 11 and the compensator 31 are joined, forces act in opposite directions to cancel each other out to form a vibration node. Since not only the translational direction component but also the rotation component around the reference axis 16 can be suppressed, the vibration insulation can be further enhanced.

By enhancing the vibration isolation in this way, the following advantages are exhibited. (1) The internal vibration system can realize a high Q value, the influence of external noise is relatively small, 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 dissipation amount of the vibration energy to the outside changes or the balance of the dissipation amount is lost in the upstream and the downstream, the internal vibration system is affected and the zero point and the span fluctuate. In the present invention, since the vibration is always trapped inside, the Coriolis mass flowmeter with high accuracy can be obtained without the concern.

(4) Even if a stress is applied from the outside, the internal vibration can continue to be stably excited by being supported by the compensator 31, that is, stable and high, which is not easily affected by piping stress or thermal stress. An accurate Coriolis mass flowmeter can be obtained.

FIG. 45 is a diagram showing the construction of the essential parts of another embodiment of the present invention, showing an embodiment of claim 8. In the present embodiment, the flexible structure portion 41 that absorbs the expansion and contraction in the direction of the reference shaft 16 and the rotational vibration around the reference shaft 16 is provided between the upstream fixed end 12, the downstream fixed end 13, and the compensator 31. Of the vibration tube 11.

As a result, since the flexible structure 41 is provided in the vibrating tube 11 between the upstream fixed end 12, the downstream fixed end 13 and the compensator 31, (1) absorbs thermal expansion. Therefore, it is possible to obtain a Coriolis mass flowmeter capable of stable and highly accurate measurement over a wide temperature range.

(2) Even when a pipe stress is applied, it can be absorbed by the flexible structure portion 41 and does not affect the inside, and a stable and highly accurate Coriolis mass flowmeter can be obtained.

[0116]

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, 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) When the dissipation amount of the vibration energy to the outside changes or the balance of the dissipation amount is lost in the upstream and downstream, the internal vibration system is affected and the zero point and the span fluctuate. In the present invention, since the vibration is always trapped inside, the Coriolis mass flowmeter with high accuracy can be obtained without the concern.

[0119]

[0120]

[0121]

Since the center of gravity of the entire vibration system is on the reference axis, even when vibration noise is applied from the outside or an impact is received, abnormal operation is unlikely to occur, such as abnormal vibration at a part away from the center of gravity. .

Further, even when the vibration is affected, it is symmetrical to the whole vibration system, and the influence is relatively uniform. Therefore, even if the vibration is not normal, it is necessary to detect vibrations at two points upstream and downstream of the vibration tube. Thus, it is possible to cancel the noise.

From the above, it is possible to obtain a stable and highly accurate Coriolis mass flowmeter which is hardly affected by external vibration or shock.

According to the second aspect of the present invention, since the center of gravity of the entire vibration system does not move, useless vibration is eliminated and vibration isolation is further enhanced. By increasing the vibration isolation in this way, the following advantages are obtained.

(1) The internal vibration system can realize a high Q value, and even if external noise is applied, its influence is relatively small and the vibration is stable, so that a Coriolis mass flowmeter that is strong against 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 dissipation of vibration energy to the outside changes or the balance of the amount of dissipation is lost in the upstream and downstream of the vibrating tube, the internal vibration system is affected and the zero point and span fluctuate. Will end up.

In the present invention, since the vibration is always trapped inside, the Coriolis mass flowmeter with high accuracy can be obtained without the concern.

(4) Even if a translational noise or shock, which is normally received from the outside, is applied and the center of gravity moves in translation, the movement is different from the normal excitation vibration. Can be easily distinguished.

It is possible to obtain a stable and highly accurate Coriolis mass flowmeter which is hardly affected by external vibration or shock.

According to claim 3 of the present invention, (1) the internal vibration system can realize a high Q value, the influence of external noise is relatively small, and the vibration is stable. A strong Coriolis mass flowmeter is 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 dissipation of vibration energy to the outside changes or the balance of the amount of dissipation is lost in the upstream and downstream of the vibrating tube, the internal vibration system is affected and the zero point and span fluctuate. Will end up. In the present invention, since the vibration is always trapped inside, the Coriolis mass flowmeter with high accuracy can be obtained without the concern.

According to the fourth aspect of the present invention, (1) If the measurement amplitude is large, the S / N is improved. On the contrary, if the measurement amplitude is comparable to the conventional one, the excitation force can be reduced and a Coriolis mass flowmeter with low power consumption can be obtained. If the maximum amplitude is small, the vibration energy is small, the leakage to the outside is small, the vibration insulation is easy, and a highly accurate and stable Coriolis mass flowmeter can be obtained.

(2) If the generated phase difference is large, the signal processing in the signal conversion portion becomes easy. That is, it is possible to obtain a Coriolis mass flowmeter that can realize stable and highly accurate performance even with a simple and inexpensive signal processing circuit.

On the other hand, if the signal processing performance is equivalent to that of the conventional one, stable measurement is possible up to a low flow rate region where the generated phase difference is small, and the mass flow rate measurement of gas having a small generated phase difference is originally possible. A possible Coriolis mass flow meter is obtained.

After all, since the amplitude and the phase difference are large, a very advantageous and dramatic improvement effect can be obtained.

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

Therefore, according to the present invention, it is possible to realize the Coriolis mass flowmeter in which the stability, accuracy and vibration resistance are improved by improving the insulation property of the internal vibration.

[Brief description of drawings]

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

FIG. 2 is a side view of FIG.

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

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

5 is an operation explanatory diagram of FIG. 1. FIG.

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

FIG. 7 is a perspective view showing the configuration of the main part of another embodiment of the present invention.

FIG. 8 is a projection view from the X direction in FIG. 7.

9 is a projection view from the Y direction of FIG. 7. FIG.

FIG. 10 is a projection view from the Z direction in FIG.

11 is a perspective view for explaining the operation of FIG. 7. FIG.

12 is a projection view from the X direction of FIG. 11. FIG.

FIG. 13 is a projection view from the Y direction of FIG.

FIG. 14 is a projection view from the Z direction in FIG.

FIG. 15 is a perspective view for explaining the operation of FIG.

16 is a projection view from the X direction of FIG.

17 is a projection view from the Y direction of FIG. 15. FIG.

FIG. 18 is a projection view from the Z direction in FIG. 15.

FIG. 19 is an explanatory perspective view showing the operation of the main parts of another embodiment of the present invention.

20 is a projection view from the X direction in FIG. 19. FIG.

21 is a projection view from the Y direction of FIG. 19. FIG.

22 is a projection view from the Z direction in FIG. 19. FIG.

23 is a front view from the Z direction in the operation explanatory view of FIG. 19. FIG.

FIG. 24 is an explanatory perspective view of the operation of FIG. 19;

FIG. 25 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 26 is an explanatory perspective view showing the operation of the main parts of another embodiment of the present invention.

27 is a projection view from the X direction of FIG. 26. FIG.

FIG. 28 is a projection view from the Y direction in FIG. 26.

FIG. 29 is a projection view from the Z direction in FIG. 26.

FIG. 30 is an explanatory perspective view showing an operation in the primary mode.

31 is a projection view from the X direction of FIG. 30. FIG.

32 is a projection view from the Y direction of FIG. 30. FIG.

FIG. 33 is a projection view from the Z direction in FIG. 30.

FIG. 34 is an explanatory perspective view showing an operation in the secondary mode.

35 is a projection view from the X direction of FIG. 34. FIG.

FIG. 36 is a projection view from the Y direction in FIG. 34.

FIG. 37 is a projection view from the Z direction of FIG. 34.

FIG. 38 is an explanatory perspective view showing the operation in the fourth mode.

FIG. 39 is a projection view from the X direction of FIG. 38.

40 is a projection view from the Y direction of FIG. 38. FIG.

41 is a projection view from the Z direction of FIG. 38. FIG.

FIG. 42 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

43 is a plan view of FIG. 42. FIG.

FIG. 44 is a side view of FIG. 42.

FIG. 45 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

[Fig. 46] Fig. 46 is a structural explanatory view of a conventional example that is generally used in the past.

[Fig. 47] Fig. 47 is a structural explanatory view of another conventional example that is generally used in the past.

48 is an explanatory diagram of the operation of FIG. 46.

49 is an explanatory diagram of the operation of FIG. 47.

FIG. 50 is an operation explanatory diagram of FIG. 47;

[Explanation of symbols]

2 flange 6 housing 11 Vibration tubes 12 upstream fixed end 13 Downstream fixed end 14 Middle Line 15 gentle curve 16 reference axes 17 Exciter 171 coil 172 Magnet 18 Vibration detection sensor 181 coil 182 magnet 19 Vibration detection sensor 191 coil 192 Magnet 21 Vibrating body 22 Vibrating body 31 Compensator 41 Flexible structure

Claims (4)

(57) [Claims] 1. A Coriolis mass flowmeter for deforming and vibrating a vibrating tube by Coriolis force, wherein at least one gentle curved portion is line-symmetrical to a midline equidistant from the upstream fixed end and the downstream fixed end. Having a straight tube connecting the upstream fixed end and the downstream fixed end as a reference axis, one vibrating tube that makes a simple vibration on a circumferential line of a predetermined distance from each point of this reference axis, and the reference axis Alternatively, it is orthogonal to the vibrating tube and has one end
Fixed to the vibration tube of the other end
Use a plate-shaped vibrating body that is placed on the opposite side of the vibrating tube.
And Bei, the mass distribution and the shape of the vibrating tube, the quality of the vibrator
The center of gravity of the entire vibration system is adjusted to the above-mentioned criteria by adjusting the quantity distribution and shape.
A Coriolis mass flowmeter characterized by being arranged on an axis . 2. A Coriolis mass flowmeter for deforming and vibrating a vibrating tube by Coriolis force, wherein at least one gentle curved portion is line-symmetric with respect to a median line equidistant from the upstream fixed end and the downstream fixed end. Having a straight tube connecting the upstream fixed end and the downstream fixed end as a reference axis, one vibrating tube that makes a simple vibration on a circumferential line of a predetermined distance from each point of this reference axis, and the reference axis Alternatively, it is orthogonal to the vibrating tube and has one end
Fixed to the vibration tube of the other end
Located on the opposite side of the vibrating tube and symmetrical to the center line
At least two plate-shaped vibrating bodies arranged at various positions
And, the vibrating body and the mass distribution and the shape and stiffness of the vibrating tube
The entire vibration system by adjusting the mass distribution, shape, rigidity, and spacing of
So that the center of gravity of is placed at the position of the vibration node of the excitation vibration
Coriolis mass flowmeter, characterized in that it is. 3. A Coriolis mass flowmeter for deforming and vibrating a vibrating tube by Coriolis force, wherein at least one gentle curved portion is line-symmetric with respect to a midline equidistant from the upstream fixed end and the downstream fixed end. Having a straight tube connecting the upstream fixed end and the downstream fixed end as a reference axis, one vibrating tube that makes a simple vibration on a circumferential line of a predetermined distance from each point of this reference axis, and the reference axis Alternatively, it is orthogonal to the vibrating tube and has one end
Fixed to the vibration tube of the other end
Located on the opposite side of the vibrating tube and symmetrical to the center line
At least two plate-shaped vibrating bodies arranged at various positions
Then, the mass distribution, shape and rigidity of the vibration tube and the vibration
Steady state excitation by adjusting body mass distribution, shape, rigidity and spacing
The force generated at both ends of the vibrating tube
Excitation by the exciter with only the twist component around the reference axis
Make sure that no component due to force is orthogonal to the reference axis
Coriolis mass flowmeter characterized by being 4. The reference shaft or the vibration tube is directly connected to the reference shaft or the vibration tube.
One end is fixed to this vibration tube and the other end is the reference
A plate-shaped member arranged on the opposite side of the vibration tube with respect to the shaft
The Coriolis mass flowmeter according to any one of claims 1 to 3 , further comprising: a vibrating body according to claim 1; and a vibration detecting sensor provided at the other end of the vibrating body .