JPH08193864A - Coriolis mass flowmeter - Google Patents

Abstract

PURPOSE: To obtain a Coriolis mass flowmeter by which a mass flow rate is measured with high accuracy by a method wherein a curved part which becomes one plane as a whole is formed at a measuring pipe in which a fluid to be measured flows and both ends of which are fixed, a vibration is applied to the plane and a change in the vibration due to Coriolis' force is detected. CONSTITUTION: Both ends of a measuring pipe 20 in which a fluid to be measured flows and in which a gently curved part 19 is provided as one plane shape are fixed by fixation members 21, 22, and a shape which is symmetric with respect to a point is formed. A vibration is applied inside of an identical plane by a vibrator 23 while the central point of symmetry is used as the belly of a vibration, electromagnetic coils 24, 25 are installed at an equal distance from both ends, and the vibration of the measuring pipe 20 is detected. The measuring pipe 20 is vibrated in a superposed manner by the vibration applied by the vibrator 23 and by a vibration due to Coriolis' force at an amplitude. Outputs of the coils 24, 25 are amplified by a preamplifier circuit part, and a tin difference and a phase difference are detected by a time-difference and phase-difference detection circuit part. In addition, the time difference and the phase difference are corrected by a flow-rate arithmetic circuit part regarding a vibration frequency, a temperature, a density, an amplitude and the like, and a mass flow rate is found. Thereby, a high-accuracy mass flowmeter can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a vibration measuring pipe having a curved pipe structure and vibrates the measuring pipe in the same direction as the plane formed by the curved pipe to realize a thin and compact structure.
The curved part reduces the influence of thermal stress and pipe stress due to temperature change, improves the temperature characteristics, can reduce the rigidity compared to the straight pipe measuring pipe with both ends fixed, and can improve the accuracy and S / N ratio by improving the sensitivity. The present invention relates to a Coriolis mass flowmeter in which the resonance frequency of each mode can be relatively freely selected by improving the flexibility of the measurement tube shape selection.

[0002]

2. Description of the Related Art FIG. 40 is an explanatory view of a configuration of a conventional example which has been generally used, for example, Japanese Patent Laid-Open No. 6-1095.
No. 12 is shown. In the figure, 1 is a flange 2
It is a straight tube type measuring tube with both ends attached. The flange 2 is for attaching the measuring tube 1 to the conduit A (not shown).

Reference numeral 3 denotes an exciter provided at the center of the measuring tube 1. The vibrator 3 vibrates the measuring tube 1 in a direction perpendicular to the central axis of the measuring tube to displace it in the vertical direction in the figure. 4,5
Are vibration detection sensors provided on both sides of the measuring tube 1. Reference numerals 6 and 7 denote fixing members for fixing both sides of the measuring tube 1, respectively.

In the above construction, when the measuring fluid is flowed through the measuring pipe 1, vibration is applied from the vibration exciter 3 installed in the central portion, as shown in FIG. The measurement tube 1 vibrates in a first-order mode shape in which is a vibration antinode.

Considering these vibrations on the upstream side and the downstream side of the measuring pipe 1, it can be considered that they are rotating around the fixed end, respectively. ω ”, and the flow velocity of the measured fluid is“ V ”(the symbol enclosed by“ ”represents a vector quantity), Fc = −2m“ ω ”ד V ”Coriolis force is proportional to Coriolis force The mass flow rate Q can be measured by measuring the amplitude of the vibration.

As a result, vibration modes M4 and M6 are generated in which the flexural vibrations are symmetrical in the upstream portion and the downstream portion with respect to the center point of the measuring pipe 1. Actually, the measuring tube 1 vibrates in a form in which these two types of vibration patterns are superimposed. The mass flow rate Q can be known by measuring this deformation with the vibration detecting means 4 and 5.

Normally, the vibration amplitude between the vibration detecting means 4 and 5 and the phase difference between the vibration detecting means 4 and 5 are obtained, correction is made by the vibration frequency and temperature, and the mass flow rate is obtained.

FIG. 41 is an explanatory view of the configuration of another conventional example which is generally used conventionally. In this conventional example, in order to further reduce noise and increase the signal, compared to the example of FIG. 39, the measuring tube 1 is of a two-tube type, and the noise is canceled.

[0009]

However, in such a device, when the measured fluid or the outside air temperature changes,
A temperature difference occurs between the measuring pipe 1 and its fixed part or the flowmeter body, and stress is applied to the measuring pipe 1 due to the effect of thermal expansion.
Vibration state (resonance frequency, vibration shape, etc.) will change.

Further, the influence of external pipe stress cannot be ignored, and it also affects the vibration state of the measuring pipe 1. Due to these phenomena, not only measurement errors of the flow rate and the density occur but also the measurement pipe 1 may cause stress fracture or fatigue fracture in some cases.

Further, a linear beam measuring tube 1 having both ends fixed
Since its rigidity is higher than that of a curved pipe, the resonance frequency is high and the generated amplitude is small. If the vibration amplitude is small at a high frequency, signal processing in the converter is difficult, the S / N tends to be poor, the accuracy is poor, the oscillation is large, the manufacturing of the converter is difficult, and the cost is high. There is.

On the other hand, FIG. 42 is a structural explanatory view of another conventional example which has been generally used in the past, taking into consideration the drawbacks of the embodiment of FIG. 39, for example, US Pat. No. 4,491.
No. 025, the title of the invention "PARALLEL PATH CORIOLIS MASS
FLOW RATE METER "filed on November 3, 1982, 198
It is shown in the 1 January 5 patent.

In the figure, reference numeral 11 is a U-shaped measuring tube having both ends attached to a pipe A. Reference numeral 12 is a mounting flange of the measuring pipe 11 to the pipe line A. Reference numeral 13 denotes a vibrator provided at the tip of the U-shaped measuring tube 11. 14, 15
Are displacement detection sensors provided on both sides of the measuring pipe 11. FIG. 43 is an explanatory view of the configuration of another conventional example which is generally used in the past.

In this conventional example, the measuring tube 11 is of a two-tube type in order to further reduce the noise and increase the signal in comparison with the embodiment of FIG. 42, and the noise is canceled. .

There is also a method of vibrating the curved measuring pipe 11 in the direction perpendicular to the plane in which the measuring pipe 11 exists, as in the embodiment shown in FIGS. In this case, the measuring tube 11
If there is no additional structure other than the above, the resonance frequency of the measuring tube 11 is predominantly determined by the length of the measuring tube 11. Therefore, the resonance frequency of excitation vibration and Coriolis vibration,
It is difficult to freely change the ratio of the resonance frequencies of those modes.

The present invention solves this problem. An object of the present invention is to provide a Coriolis mass flowmeter that is thin and compact, has improved temperature characteristics, high accuracy, improved S / N ratio, and has a greater degree of freedom in selecting the shape of a measuring tube.

[0017]

In order to achieve this object, the present invention provides (1) a measuring fluid is caused to flow in an oscillating measuring tube, and the flow of the measuring fluid and Coriolis force generated by angular vibration of the measuring tube In a Coriolis mass flowmeter for deforming and vibrating a measuring pipe and measuring a change in vibration with a vibration detecting sensor to determine a mass flow rate and a density, a measuring pipe having both ends fixed and through which the measuring fluid flows, and a measuring pipe provided on the measuring pipe. At least one curved portion arranged so as to be arranged in one plane as a whole of the measuring tube, an exciter for exciting the measuring tube in the plane direction on the plane, and measurement by the Coriolis force. A Coriolis mass flowmeter, comprising: a vibration detection sensor for detecting a change in vibration of a pipe. (2) Two measuring pipes having the same shape and arranged on the same plane and parallel to each other, and one of the measuring pipes having one end attached thereto and the other measuring pipe having the other end attached thereto And one end is attached to the one measuring pipe and the other end is attached to the other measuring pipe or the Coriolis mass flowmeter main body, and relative vibration of the two measuring pipes or absolute vibration with respect to the Coriolis mass flowmeter main body The Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor for detecting (3) Two measuring tubes that have the same shape and are arranged in line symmetry or point symmetry with each other on the same plane, and one measuring tube has one end attached and the other measuring tube has the other end attached And one end attached to the one measuring pipe and the other end attached to the other measuring pipe or the Coriolis mass flowmeter main body, and relative vibration of the two measuring pipes or Coriolis mass flowmeter main body 2. A Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor for detecting an absolute vibration with respect to. (4) Two measuring tubes having the same shape and arranged on two different planes parallel to each other and parallel to each other, and one measuring tube has one end attached to the other measuring tube and the other measuring tube has the other end. Attached vibrator and one end attached to the one measuring pipe and the other end attached to the other measuring pipe or the Coriolis mass flowmeter main body, relative vibration of the two measuring pipes or Coriolis mass flowmeter The Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor that detects an absolute vibration with respect to the main body. Is configured.

[0018]

In the above structure, when the measuring fluid is flown into the measuring tube and the vibrator is driven, the Coriolis force acts. By measuring the amplitude of vibration proportional to this Coriolis force, the mass flow rate can be measured. . 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 structure of an embodiment of the present invention. Reference numeral 20 denotes a measuring pipe having a curved portion 19 through which the measuring fluid flows, and both ends of the measuring pipe 20 are fixed by fixing members 21 and 22. In this configuration example, the measuring tube 2
The shape of 0 is a measurement tube shape that is point-symmetric with respect to a point that is equidistant from both fixed ends.

A vibration exciter 23 is installed on the measuring tube 20 to generate vibration such that a point at the center of symmetry is an antinode of the vibration within a plane determined by the fixed end and the measuring tube 20. As the vibration detection sensor, the electromagnetic coil 24 and the electromagnetic coil 25 are used to detect the vibration (speed) of the vibration measuring tube. The coils 24 and 25 are installed at positions equidistant from both fixed ends.

FIG. 2 shows a general example of a signal processing system. Sensor part 261, preamplifier circuit part 262, time (difference) / phase
(Difference) detection circuit unit 263, flow rate calculation circuit unit 264, and vibration circuit unit 265.

In the above structure, the vibration measuring tube 20 is
The vibrator 23 vibrates as shown by M21, M22, and M23 in FIG. At this time, when the fluid flows in the measuring pipe, Coriolis force is generated, and M24, M25, M26 in FIG.
A vibration mode like this occurs.

Actually, the exciting vibration (M21, M2
2, M23) and vibration due to Coriolis force (M24, M2
5, M26), the measuring tube 20 vibrates in a form in which two types of vibration patterns are superimposed. When the vibration amplitude due to the excitation vibration is A and the vibration amplitude due to the Coriolis vibration is C (C = kQ, Q is a mass flow rate) (generally A >> C), the sensor coil 24
And the outputs of 25 are: coil 24: S ₂₄ = Asinθ + Ccosθ = A'sin (θ
+ Δ) Coil 25: S ₂₅ = Asinθ-Ccosθ = A'sin (θ
−δ) where A ′ = (A ² + C ² ) ^1/2 , δ = atan (C / A) ≈
k'Q and k, k 'are constants

The sensor signal is amplified by the preamplifier circuit section 262 by the signal processing circuit of FIG. 2, and the time (difference) / phase (difference)
The detection circuit unit 263 detects a time difference or a phase (difference) between the outputs of the two sensors. Further, the mass flow rate is obtained by correcting the vibration frequency, temperature, density, amplitude, etc. in the flow rate calculation circuit section 264. In addition, the measuring circuit 2
A drive signal for exciting 0 is generated.

As a result, (1) it becomes possible to place the measuring pipe 20, the vibrator 23, and the vibration detection sensors 24 and 25 on the same plane even with a double pipe, and it is possible to realize a thin and compact Coriolis mass flowmeter. . (2) By using the measuring pipe 20 having the curved pipe portion 19, it is possible to reduce the influence of thermal stress, pipe stress, etc. due to the fluid and the ambient temperature. As a result, it is possible to realize a highly accurate Coriolis mass flowmeter that is stable against changes in the external environment and has good temperature characteristics.

(3) Since the measuring pipe 20 has the curved portion 19 unlike the straight pipe measuring pipe, even if the same detector case size is used, the measuring pipe length can be made long, so that the vibration amplitude can be easily obtained and the measuring pipe can be comparatively obtained. A large vibration sensor output can be obtained. As a result, the load on the converter is reduced, the S / N ratio is improved, oscillation is reduced, and further improvement in accuracy can be expected.

(4) In the conventional method of vibrating vertically with respect to the plane formed by both fixed ends and the curved measuring tube, the resonance frequency of each vibration mode is largely determined by the length of the measuring tube. To do. On the other hand, in the present invention in which the vibration direction is also the same, the resonance frequency of each mode greatly depends on the shape of the measuring tube. Therefore, since the degree of freedom in design is great, it is easy to give various characteristics.

(5) Since it has a gentle curved portion 19,
Despite being a curved pipe, the pressure loss and self-drainability are close to those of a straight pipe and have a gentle curve,
It has a strong resistance to thermal stress and piping stress.

FIG. 4 is an explanatory view of a main part configuration of another embodiment of the present invention, and FIGS. 5 and 6 are operation explanatory views of FIG. In this embodiment, reference numerals 30 and 31 denote measuring tubes having a curved portion 29, and the fluid flowing into the Coriolis mass flowmeter is 2 at the inlet.
Divide into two and merge into one at the exit. The two identical shape measuring tubes 30 and 31 are installed in parallel in the same plane.
32 and 33 are measuring tube fixing members, 34 is a vibrator, 35,
Reference numeral 36 is a sensor coil that detects relative vibration of the two measuring tubes 30 and 31.

In the above structure, the vibration measuring tubes 30, 3
1 is generated by the vibration exciter 36 from M31, M32, M3 in FIG.
Vibration as shown in FIG. At this time, when the fluid flows in the measuring pipe, Coriolis force is generated, and M34, M35,
A vibration mode as shown by M36 occurs.

Actually, the measuring tube 30 vibrates in a form in which the two types of vibration patterns shown in FIGS. 5 and 6 are superimposed. The relative vibrations of the vibration measuring tubes 30 and 31 are obtained by the sensor coils 35 and 36, and the output is the coil 35: S ₃₅ = Asinθ + Ccosθ = A'sin (θ
+ Δ) Coil 36: S ₃₆ = Asinθ-Ccosθ = A'sin (θ
−δ).

As a result, also in the present embodiment, the Coriolis mass flowmeter which has a shape and pressure loss close to that of a straight pipe, has excellent self-draining property, and has a gentle curved portion 29, is resistant to thermal stress and piping stress. can get.

Further, since the two measuring tubes 30 and 31 vibrate in mutually opposite directions, the stresses cancel each other out at the fixing portions at both ends, and the vibration isolation is excellent due to the effect of the tuning fork. As a result, the energy applied to the vibrator 34 can be small.
Further, since the Q value is high, it is less likely to be affected by external vibration noise. Also, the vibration of itself does not leak to the outside and adversely affect the vibration system. Therefore, a Coriolis mass flowmeter excellent in vibration resistance can be realized.

FIG. 7 is an explanatory view of the essential structure of another embodiment of the present invention, and FIGS. 8 and 9 are operation explanatory views of FIG. In the present embodiment, reference numerals 40 and 41 each have a curved portion 39 near the fixed end, and have a total of two curved portions 39. The fluid flowing into the Coriolis mass flowmeter is branched into two at the inlet. , Also, join one at the exit.

The two identical-shape measuring tubes 40 and 41 are present in the same plane and are installed in line-symmetrical or point-symmetrical positions. 42 and 43 are fixing members for the measuring pipes, 44 and 45 are vibrators, and 46 and 47 are sensor coils for detecting relative vibration of the two measuring pipes 40 and 41.

In the above construction, the measuring tubes 40 and 41 are moved by the vibrators 44 and 45 to M41, M42 and M4 of FIG.
Vibration as shown in FIG. At this time, when the fluid flows into the measuring pipe, Coriolis force is generated, and M44, M45,
Vibration as shown by M46 is performed (the vibration shape is determined by the resonance frequency and the excitation frequency of each vibration mode. Therefore, the exact shape may be slightly different). Actually, the measuring tube vibrates in a form in which the two types of vibration patterns of FIGS. 8 and 9 are superposed. The relative vibrations of the vibration measuring tubes 40 and 41 are obtained by the sensor coils 46 and 47, and their outputs are as follows.

Coil 46: S ₄₆ = A sin θ + C cos θ =
A'sin (θ + δ) coil 47: S ₄₇ = -Asinθ + Ccosθ = -A'sin
(Θ−δ) Note that the signal processing is the same as in FIG. However,
Since the output of the coil 46 has a sign opposite to that in the embodiment of FIG. 1, the sign inversion or 180-degree phase shift means is usually used together.

As a result, also in this embodiment, a Coriolis mass flowmeter having a shape close to a straight pipe, a pressure loss, and an excellent self-draining property can be obtained.

Further, since the measuring tubes 40 and 41 each have the curved portion 39 near the fixed end, the rigidity is low, a relatively large vibration can be obtained, and the S / N ratio is excellent and the precision is high. It can realize various flow meters. Further, since the two measuring tubes vibrate in opposite directions, a Coriolis mass flowmeter excellent in vibration resistance can be obtained as in the case of the embodiment of FIG.

FIG. 10 is an explanatory view of the essential structure of another embodiment of the present invention, and FIGS. 11, 12, 13, and 14 are explanatory views of the operation of FIG.

In the present embodiment, reference numerals 50 and 51 are U-shaped pipes through which a measuring fluid flows, which are divided into two at the inlet of the flowmeter and merge at the outlet. The two identical shape measurement tubes 50 and 51 are installed on two different planes parallel to each other. Reference numeral 52 is a fixing member of the measuring pipe, 53 and 54 are vibrators, and 55 and 56 are vibration detecting sensors for detecting relative vibration of the two measuring pipes. In this case, a coil sensor is used.

In the above structure, the vibration measuring tube 50,
Is moved by the shakers 53 and 54 to move the M5 of FIG.
Vibration such as 1, M52 and M53 is performed. On the other hand, the vibration measuring tube 51 vibrates on the paper surface as indicated by M51, M52, and M53 in FIG. 12 by the vibrators 53 and 54 (as shown in FIG. 10, the measuring tube 50 and the measuring tube 51 are There is a parallel positional relationship with different Z coordinates.)

At this time, when the measuring fluid flows in the measuring pipes 50 and 51, Coriolis force is generated, and M5 in FIGS.
4, M55 and M56 are vibrated (as shown in FIG. 10, the measuring tube 50 and the measuring tube 51 have a parallel positional relationship in which the Z coordinates are different). Actually, the measuring tube 50 vibrates in a shape in which the two types of vibration patterns of FIG. 11 and FIG. 13 are superimposed.

On the other hand, the measuring tube 51 is the same as that shown in FIG.
It vibrates in a shape in which different types of vibration patterns are superimposed. The relative vibration of the measuring tubes 50 and 51 is obtained by the sensor coils 55 and 56, and the output is as follows. Coil 55: S ₅₅ = Asinθ + Ccosθ = A'sin (θ
+ Δ) Coil 56: S ₅₆ = Asinθ-Ccosθ = -A'sin
(Θ-δ)

As a result, since the rigidity can be lowered, a relatively large vibration can be obtained, and a highly accurate Coriolis mass flowmeter having an excellent S / N ratio can be obtained. Further, due to the presence of the curved portion, it is possible to realize a Coriolis mass flowmeter that is resistant to thermal stress and piping stress.

In the above-mentioned embodiment, the branching and merging in the case where the measuring pipe is a double pipe has been described as being outside the fixed end, but the present invention is not limited to this and may be inside the fixed end. For example, the configuration shown in FIG. 15 corresponds to the embodiment of FIG.

Further, in the four examples shown in FIGS. 1, 4, 7, and 10, the respective examples are shown in which the vibrations are excited in the specific vibration modes, and thereby the deformation is caused by the specific Coriolis force. However, even with the shape of the measuring tube shown here, it is possible that it is excited in different vibration modes and causes different deformation due to the generated Coriolis force. Further, even if the shape of the measuring tube is the same, both a single tube and a parallel tube are conceivable. Particularly, in the case of a double tube, it is conceivable that the measuring tubes vibrate in the same direction or in the opposite directions. Examples of possible combinations of the shapes of the measuring tube 20 shown in the embodiment of FIG. 7 are shown in FIGS. 16 to 20 below.

In FIG. 16, the measuring pipe 20 of the single pipe of the embodiment shown in FIG. 1 is changed to the arrow a in the secondary mode as shown in FIG.
The vibration is applied in the direction. When the measuring fluid flows in the measuring tube 20, Coriolis force is generated, and
A vibration mode as shown in 7 occurs.

FIG. 18 shows a case in which a two-pipe measuring pipe 20 is used. The two-pipe measuring pipes 20 are arranged on the same plane and in parallel with each other, and are vibrated in the direction of arrow a. Thus, the vibration is detected by measuring the relative position of the measuring tube 20 having two tubes.

FIG. 19 uses a double-pipe measuring pipe 20. The double-pipe measuring pipes 20 are arranged in a symmetric relationship with each other on the same plane and are vibrated in the direction of arrow a. The vibration is detected by measuring the absolute position of the measuring pipe 20 having two pipes.

FIG. 20 uses a two-tube measuring tube 20. The two-tube measuring tube 20 is on a different plane.
They are arranged so as to be parallel to each other and are vibrated in the direction of arrow a, and the vibration is detected by measuring the relative position of the measuring pipe 20 of the two pipes.

Next, the arrangement of the two measuring tubes 20 is parallel or axisymmetric to each other, the vibration direction is the same direction vibration or the reverse direction vibration, the vibration mode is the first mode excitation or the higher mode excitation, For vibration detection, absolute position measurement or relative position measurement can be adopted.

Therefore, various combinations can be realized by combining these elements. In addition, various shapes of the measuring tube can be considered. For each shape, 1-tube or 2-tube, 1-mode excitation, 2-mode or higher-order mode excitation, vibration detection sensor is fixed member reference absolute position measurement, or 2 measurement tubes There is a selection factor of relative position measurement, or in the case of two measuring tubes, whether the measuring tubes are arranged on the same plane or on different planes, and at that time, the measuring tubes are arranged in a parallel relationship or a symmetrical relationship. Various combinations can be realized by combining these elements.
21 to 33 for the embodiment mainly focusing on the shape of the measuring tube.
Shown in

21 and 22, the S-shaped measuring tube 61 is adopted and is vibrated in the direction of arrow a. 23 and 24, the Ω-shaped measuring tube 62 is adopted and is vibrated in the direction of the arrow a.

25 and 26, a U-shaped measuring tube 63 is adopted and is vibrated in the direction of arrow a. 27 and 28, a W-shaped measuring tube 64 is adopted and is vibrated in the direction of arrow a.

29 to 33, a linear measuring tube 66 having one curved portion 65 is adopted and is vibrated in the direction of arrow a.

34 to 38, as shown in FIG.
It has curved portions 68 at both ends, and the straight pipe portion 6 is provided at the central portion.
Adopting a trapezoidal measuring tube 67 having 9 as a whole,
The vibration is applied in the direction of arrow a.

FIG. 34 is a shape diagram of the measuring tube 67, FIG.
FIG. 37 shows a vibrating state, and FIG. 35 shows a measuring tube 67.
37, and the both ends of the straight pipe portion 69 in FIG. 36 and 38 show the displacement state of the measuring tube 67 due to the generated Coriolis force based on the vibration shown in FIG. 35 or 37.

In the present embodiment, since a large Coriolis force is obtained, the deformation of the measuring tube 67 becomes large, and as a result, a large phase difference is obtained, and a Coriolis mass flowmeter with a highly accurate measurement value is obtained. I can do things.

In the above embodiment, the case where the vibration detecting sensor is an electromagnetic coil (speed sensor) has been described, but the invention is not limited to this, and a displacement sensor, a stress sensor, or a strain sensor may be used. . In short, it is sufficient if the vibration of the measuring tube can be detected.

In the above-described embodiment, the method of detecting the time (difference) or the phase (difference) is shown in the signal processing explanatory diagram of FIG. 2, but the present invention is not limited to this.
For example, a method of separating the excitation component and the Coriolis component by synchronous rectification and integration and obtaining the mass flow rate from the ratio may be used.
In short, any method capable of signal processing may be used.

[0062]

As described above, according to the present invention, (1) a measuring fluid is caused to flow in an oscillating measuring tube, and the measuring tube is deformed and vibrated by the Coriolis force generated by the flow of the measuring fluid and the angular vibration of the measuring tube. In a Coriolis mass flowmeter for measuring a change in vibration with a vibration detection sensor to determine a mass flow rate and a density, a measuring tube having both ends fixed and through which the measuring fluid flows, and one measuring tube provided in the measuring tube as a whole At least one curved portion arranged in the plane, a vibrator for exciting the measurement tube in the plane direction on the plane, and a change in vibration of the measurement tube due to the Coriolis force. A Coriolis mass flowmeter, comprising a vibration detection sensor for detecting. (2) Two measuring pipes having the same shape and arranged on the same plane and parallel to each other, and one of the measuring pipes having one end attached thereto and the other measuring pipe having the other end attached thereto And one end is attached to the one measuring pipe and the other end is attached to the other measuring pipe or the Coriolis mass flowmeter main body, and relative vibration of the two measuring pipes or absolute vibration with respect to the Coriolis mass flowmeter main body The Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor for detecting (3) Two measuring tubes that have the same shape and are arranged in line symmetry or point symmetry with each other on the same plane, and one measuring tube has one end attached and the other measuring tube has the other end attached And one end attached to the one measuring pipe and the other end attached to the other measuring pipe or the Coriolis mass flowmeter main body, and relative vibration of the two measuring pipes or Coriolis mass flowmeter main body 2. A Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor for detecting an absolute vibration with respect to. (4) Two measuring tubes having the same shape and arranged on two different planes parallel to each other and parallel to each other, and one measuring tube has one end attached to the other measuring tube and the other measuring tube has the other end. Attached vibrator and one end attached to the one measuring pipe and the other end attached to the other measuring pipe or the Coriolis mass flowmeter main body, relative vibration of the two measuring pipes or Coriolis mass flowmeter The Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor that detects an absolute vibration with respect to the main body. Was configured.

As a result, (1) it is possible to place the measuring pipe 20, the vibrator 23, and the vibration detection sensors 24 and 25 on the same plane even with a two-pipe structure, and it is possible to realize a thin and compact Coriolis mass flowmeter. .

(2) By using the measuring pipe 20 having the curved pipe portion 19, it is possible to reduce the influence of thermal stress, pipe stress, etc. due to the fluid and the ambient temperature. As a result, it is possible to realize a highly accurate Coriolis mass flowmeter that is stable against changes in the external environment and has good temperature characteristics.

(3) Since the measuring pipe 20 has the curved portion 19 unlike the straight pipe measuring pipe, even if the same detector case size is used, the measuring pipe length can be made long, so that the vibration amplitude can be easily obtained, and it is comparatively easy to obtain. A large vibration sensor output can be obtained. As a result, the load on the converter is reduced, the S / N ratio is improved, oscillation is reduced, and further improvement in accuracy can be expected.

(4) In the conventional method of vibrating vertically with respect to the plane formed by both fixed ends and the curved measuring tube, the resonance frequency of each vibration mode is largely determined by the length of the measuring tube. To do. On the other hand, in the present invention in which the vibration direction is also the same, the resonance frequency of each mode greatly depends on the shape of the measuring tube. Therefore, since the degree of freedom in design is great, it is easy to give various characteristics.

(5) Since it has a gentle curved portion 19,
Despite being a curved pipe, the pressure loss and self-drainability are close to those of a straight pipe and have a gentle curve,
It has a strong resistance to thermal stress and piping stress.

Furthermore, according to the second aspect, the noise resistance characteristic is good by differentially processing the vibration signals of the two measuring tubes while having a shape and pressure loss close to those of a straight tube and excellent self-draining property. A Coriolis mass flow meter is obtained. Furthermore, if the vibration directions of the two measuring tubes are made opposite to each other, a Coriolis mass flowmeter excellent in vibration insulation can be obtained.

Further, according to the third aspect, the Coriolis mass flow rate has a shape and pressure loss close to that of a straight pipe, is excellent in self-draining property, noise resistance property, and vibration insulating property, and further has an increased degree of freedom in design. The total is obtained.

Further, according to claim 4, the two measuring tubes can be present on different planes while having a shape close to a straight tube, pressure loss, and excellent self-draining property, noise resistance property and vibration insulating property. Furthermore, a Coriolis mass flowmeter with an increased degree of design freedom can be obtained.

Therefore, according to the present invention, it is possible to realize a Coriolis mass flowmeter which is thin and compact, has improved temperature characteristics, high accuracy, improved S / N ratio, and has a greater degree of freedom in selecting the shape of a measuring tube. Can be done.

[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 an explanatory diagram of signal processing of FIG.

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

FIG. 4 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

5 is an operation explanatory diagram of FIG. 4;

FIG. 6 is an operation explanatory diagram of FIG. 4;

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

FIG. 8 is an operation explanatory diagram of FIG. 7;

9 is an operation explanatory diagram of FIG. 7. FIG.

FIG. 10 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

11 is an operation explanatory diagram of FIG. 10;

12 is an operation explanatory diagram of FIG. 10. FIG.

13 is an explanatory diagram of the operation of FIG.

14 is an explanatory diagram of the operation of FIG.

FIG. 15 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 16 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 17 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

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

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

FIG. 22 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

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 main part configuration of another embodiment of the present invention.

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

FIG. 26 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 27 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 28 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 29 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 30 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 31 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 32 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 33 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 34 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 35 is an operation explanatory diagram of FIG. 35;

36 is an explanatory diagram of the operation of FIG. 35.

37 is an explanatory diagram of the operation of FIG. 35.

38 is an explanatory diagram of the operation of FIG. 35.

FIG. 39 is an explanatory diagram of a configuration of a conventional example that is generally used from the past.

FIG. 40 is an operation explanatory diagram of FIG. 39;

FIG. 41 is a diagram illustrating the configuration of another conventional example that is generally used in the past.

[Fig. 42] Fig. 42 is a structural explanatory view of a conventional example that is generally used in the past.

[Fig. 43] Fig. 43 is a configuration explanatory view of another conventional example that is generally used in the past.

[Explanation of symbols]

 19 Bending part 20 Measuring tube 21 Fixing member 22 Fixing member 23 Exciter 24 Vibration detection sensor 25 Vibration detection sensor 261 Sensor part 262 Preamplifier 263 Time (difference) / phase (difference) detection circuit part 264 Flow rate calculation circuit part 265 Excitation circuit section 29 Curved section 30 Measuring tube 31 Measuring tube 32 Fixing member 33 Fixing member 34 Exciter 35 Vibration detection sensor 36 Vibration detection sensor 39 Curved section 40 Measuring tube 41 Measuring tube 42 Fixing member 43 Fixing member 44 Exciter 45 Exciter 46 Vibration Detection Sensor 47 Vibration Detection Sensor 49 Curved Part 50 Measuring Tube 51 Measuring Tube 52 Fixing Member 53 Exciter 54 Exciter 55 Vibration Detection Sensor 56 Vibration Detection Sensor 61 Measuring Tube 62 Measuring Tube 63 Measuring Tube 64 Measuring tube 65 Curved section 66 Measuring tube 67 Measuring tube 68 Curved section 69 Straight tube section

Front page continuation (72) Inventor Hideki Kuwayama 2-9-32 Nakamachi, Musashino City, Tokyo Yokogawa Electric Co., Ltd.

Claims (4)

[Claims] 1. A measuring fluid is flown into an oscillating measuring tube, and the Coriolis force generated by the flow of the measuring fluid and the angular vibration of the measuring tube causes the measuring tube to deform and vibrate. In a Coriolis mass flowmeter for determining a flow rate and a density, a measuring tube having both ends fixed and through which the measuring fluid flows, and at least one measuring tube provided on the measuring tube and arranged as one whole in the measuring tube. A plurality of bending portions, a vibration exciter that vibrates the measurement tube in the plane direction on the plane, and a vibration detection sensor that detects a change in vibration of the measurement tube due to the Coriolis force. Coriolis mass flow meter. 2. Two measuring pipes having the same shape and arranged on the same plane and parallel to each other, one measuring pipe having one end attached thereto and the other measuring pipe having the other end attached thereto. A shaker, one end of which is attached to the one measuring pipe and the other end of which is attached to the other measuring pipe or the Coriolis mass flowmeter main body, and relative vibration of the two measuring pipes or absolute with respect to the Coriolis mass flowmeter main body. The Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor that detects dynamic vibration. 3. Two measuring pipes having the same shape and arranged on the same plane and line-symmetrically or point-symmetrically to each other, and one measuring pipe has one end attached to the other measuring pipe. , And one end is attached to the one measuring pipe and the other end is attached to the other measuring pipe or the Coriolis mass flowmeter body, and the relative vibration of the two measuring pipes or the Coriolis mass flow rate. The Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor that detects an absolute vibration with respect to the main body of the meter. 4. Two measuring tubes having the same shape and arranged on two different planes parallel to each other and parallel to each other; one measuring tube having one end attached to the other measuring tube; A shaker with one end attached, and one end attached to the one measurement pipe and the other end attached to the other measurement pipe or the Coriolis mass flowmeter main body and relative vibration or Coriolis mass of the two measurement pipes. The Coriolis mass flowmeter according to claim 1, further comprising a vibration detection sensor that detects an absolute vibration with respect to the flowmeter main body.