Coriolis flowmeter

Abstract

To facilitate the manufacture of a Coriolis flowmeter by making it possible to omit the step of adjusting the mass balance. [Solution] A measurement fluid flows through a flow tube (1). At least one of a first coil and a second coil that are provided on the surface of the flow tube (1) and detect vibrations of the flow tube (1), and a third coil that excites the flow tube (1) is a thin-film patterned coil. A first magnet is provided in a position facing the first coil. A second magnet is provided in a position facing the second coil. A third magnet is provided in a position facing the third coil.

Description

[Technical Field]

[0001] The present invention relates to a Coriolis flowmeter. [Background technology]

[0002] Coriolis flowmeters are known as one type of flowmeter used in plants. Coriolis flowmeters vibrate a vibrating tube through which a fluid flows by exciting a coil, and measure the Coriolis force generated by the fluid passing through the inside of the vibrating tube through the torsion of the vibrating tube. U-shaped or straight tubes are used as vibrating tubes.

[0003] A Coriolis flowmeter has a flow tube in which Coriolis force is generated due to fluid flow. Sensors for detecting velocity amplitude are installed on the flow tube at symmetrical positions on the upstream and downstream sides of the center axis. The Coriolis flowmeter obtains a phase difference reflecting the torsion of the flow tube caused by the Coriolis force from a signal waveform based on the velocity amplitude obtained by these sensors, and calculates the mass flow rate. Because the Coriolis force increases with the fluid flow rate, the Coriolis flowmeter can measure the flow rate via the width and phase of the torsion of the vibrating tube.

[0004] The phase difference used to calculate mass flow rate is affected by the symmetry of the flow tube's shape, and by disturbances in the symmetry of the various sensors attached to the flow tube and the mass of the flow tube itself. Hereinafter, the various symmetries that affect the phase difference are referred to as "mass balance." In Coriolis flowmeters, if there is a disturbance in the mass balance, the phase difference corresponding to the flow rate cannot be accurately detected. Therefore, to minimize measurement error factors, it is necessary to adjust the mass balance by adjusting the flow tube's manufacturing precision or by adding mass to the sensor during the manufacturing process.

[0005] In most conventional Coriolis flowmeters, a pair of coils and magnets are used as sensors to detect velocity amplitude, and a voltage waveform is obtained as an induced electromotive force from changes in magnetic flux linkage due to flow tube vibration displacement, and the phase difference is calculated from this. Alternatively, the flow tube vibration displacement can be obtained as an electrical signal using a strain gauge or piezoelectric element, and the phase difference can be calculated from the obtained electrical signal.

[0006] Another proposed Coriolis flowmeter is one in which a thin conductive pattern is formed on the surface of a sensor tube, one end of the conductive pattern is connected to a vibrator, and the other end of the conductive pattern is connected to an electric circuit (see, for example, Patent Document 1). Another proposed device has a pair of sensor tubes, one of which is provided with a magnet, and the other of which is provided with a thin-film sensor that outputs a signal according to the amount of relative displacement between the magnet (see, for example, Patent Document 2). Another proposed technology is a ceramic sensor equipped with a coil formed on a piezoelectric or electrostrictive element and a voltmeter that measures the voltage generated in the vibrating coil (see, for example, Patent Document 3). Another proposed vibration sensor has a detection coil formed by patterning it in a spiral on the surface of a substrate (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-129889 [Patent Document 2] Japanese Patent Application Publication No. 4-77623 [Patent Document 3] Japanese Patent Application Publication No. 11-142492 [Patent Document 4] Japanese Patent Application Laid-Open No. 2003-66063 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in conventional methods using a pair of coils and magnets, or methods using strain gauges or piezoelectric elements, the sensor has a mass of at least several grams and requires structural components for attachment to the flow tube. Therefore, achieving a mass difference that cannot be ignored due to the mass balance is difficult, and adjustment of the flow tube vibration characteristics is required, such as by adding additional mass or by selecting and pairing components with similar masses in advance. Furthermore, the positioning of components during installation must be performed with high precision to achieve symmetry of the mass points. In addition to the sensor, sensor signal lines can also disrupt the symmetry of the flow tube. For example, if a sensor signal line is installed along the flow tube using adhesive, it can disrupt the mass balance of the entire flow tube. As such, manufacturing conventional Coriolis flowmeters has been challenging.

[0009] Furthermore, while a technology that forms a thin conductive pattern on the surface of a sensor tube can reduce the mass of the signal wire itself, it focuses on eliminating the mass balance effect of each signal wire, making it difficult to eliminate the mass balance effect caused by the sensor. Furthermore, a technology that uses a magnet on one side of a pair of sensor tubes and a thin-film sensor on the other side excites the flow tube using an exciter coil with a coil bobbin, making it difficult to eliminate the mass balance effect of all components attached to the flow tube. Furthermore, although the sensor principle uses the magnetoresistive effect, the resistance waveform obtained using this measurement principle is easily affected by changes in the resistance of the sensor film due to fluid temperature, which may reduce measurement accuracy. Furthermore, sensors that use coiled conductive pattern coils, such as ceramic sensors with a coil formed on a piezoelectric or electrostrictive element or vibration sensors with a detection coil patterned spirally on the surface of a substrate, have not been considered for use with flow tubes in Coriolis flowmeters. Therefore, regardless of the technology used, complex processes remain required to eliminate the mass balance effect, making it difficult to easily manufacture Coriolis flowmeters.

[0010] One aspect of the present invention facilitates the manufacture of a Coriolis flowmeter. [Means for solving the problem]

[0011] A Coriolis flowmeter according to one aspect has the following components: A measurement fluid flows through a flow tube; at least one of a first coil and a second coil provided on the surface of the flow tube for detecting vibrations and a third coil for exciting the flow tube is a thin-film patterned coil; a first magnet is provided in a position facing the first coil; a second magnet is provided in a position facing the second coil; and a third magnet is provided in a position facing the third coil. [Effects of the Invention]

[0012] According to the present invention, the Coriolis flowmeter can be easily manufactured. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a perspective view of a detection unit in the Coriolis flowmeter according to the first embodiment. [Figure 2] FIG. 2 is a front view of a detection unit in the Coriolis flowmeter according to the first embodiment. [Figure 3] FIG. 2 is an enlarged view of a pickup thin-film coil. [Figure 4] FIG. 2 is a diagram showing wiring between a thin-film pattern coil and a signal converter. [Figure 5] 5A to 5C are diagrams illustrating operations when acquiring a pickup signal according to the first embodiment. [Figure 6] FIG. 10 is a perspective view of a detection unit in a Coriolis flowmeter according to a second embodiment. [Figure 7] 10A and 10B are diagrams illustrating operations when acquiring a pickup signal according to the second embodiment. [Figure 8] FIG. 11 is a perspective view of a detection unit in a Coriolis flowmeter according to a third embodiment. [Figure 9] FIG. 10 is an enlarged view of a portion of the pickup thin-film coil according to the third embodiment. [Figure 10] FIG. 10 is a simplified diagram of a pickup thin-film coil according to a third embodiment. [Figure 11]FIG. 10 is a plan view of a detector according to a third embodiment. [Figure 12] 10A to 10C are diagrams illustrating the operation of the vibrator according to the third embodiment. [Figure 13] 10A and 10B are diagrams illustrating operations when a pickup signal is acquired according to the third embodiment. [Figure 14] FIG. 10 is a plan view of a detection unit in a Coriolis flowmeter according to a fourth embodiment. [Figure 15] FIG. 11 is a perspective view of a detection unit in a Coriolis flowmeter according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of a Coriolis flowmeter will be described with reference to the drawings. The same elements are denoted by the same reference numerals, and duplicated descriptions will be omitted as appropriate. Furthermore, the embodiments can be combined as appropriate within a range that does not cause inconsistencies.

[0015] (First embodiment) (Overall composition) 1 is a perspective view of a detection unit in a Coriolis flowmeter according to a first embodiment. The detection unit 100 vibrates a flow tube 1 through which a fluid to be measured flows, and detects the vibrations upstream and downstream and the temperature of the flow tube 1. Although not shown, the Coriolis flowmeter also includes a signal converter in addition to the detection unit 100. The signal converter determines the phase difference between detection signals SA and SB detected by the detection unit 100 to determine the mass flow rate of the fluid flowing through the flow tube 1.

[0016] The detection unit 100 includes a flow tube 1, flanges 2a and 2b, pickup thin-film coils 3a and 3b, a vibrator thin-film coil 4, magnets 5a and 5b, and a magnet 6.

[0017] Here, the longitudinal direction of the flow tube 1 as shown in Fig. 1 is defined as the x-axis. The direction in which the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 face the magnets 5a and 5b and the magnet 6 is defined as the z-axis. Furthermore, the direction perpendicular to the x-axis and z-axis is defined as the y-axis. In the following description, the x, y, and z directions may be used.

[0018] 2 is a front view of a detection unit in the Coriolis flowmeter according to the first embodiment. A flow tube 1 forms a flow path for a measurement fluid in the Coriolis flowmeter.

[0019] As shown in Figure 2, the flow tube 1 according to this embodiment is a straight tube. Flanges 2a and 2b are connected to both ends of the flow tube 1 in the flow direction. The flanges 2a and 2b are joints between the flow tube 1 and external piping, enabling their connection. However, the shape of the joint between the flow tube 1 and external piping is not limited to the shape of the flanges 2a and 2b, and may be a clamp type or a screw type.

[0020] The flanges 2a and 2b are made of a metal such as stainless steel. The flanges 2a and 2b are, for example, disk-shaped, with a through-hole at the center of the disk that serves as the flow path. The inner diameter of the through-hole in the flanges 2a and 2b matches the inner diameter of the flow tube 1. A full-bore flow path is formed by joining one end of the flow tube 1 in the flow direction to the end face of the non-joint-shaped portion of the flange 2a, which is opposite to the surface to which the external piping is connected, by welding or brazing. Similarly, a full-bore flow path is formed by joining the other end of the flow tube 1 in the flow direction to the end face of the non-joint-shaped portion of the flange 2b by welding or brazing.

[0021] Two pickup thin-film coils 3a and 3b, which are thin-film pattern coils, and one vibrator thin-film coil 4 are installed on the surface of the flow tube 1. In this embodiment, the vibrator thin-film coil 4 is located at the center of the flow tube 1 in the flow direction. The pickup thin-film coils 3a and 3b are each located symmetrically about the center between the center and the ends of the flow tube 1 in the flow direction. The installation positions of the pickup thin-film coils 3a and 3b in the flow direction are preferably determined by design according to the vibration characteristics based on the shape and dimensions of the flow tube. The flow direction of the flow tube 1 coincides with the x-axis. The pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 are aligned in a row in the x-direction.

[0022] The pickup thin-film coils 3a and 3b are an example of a "first coil and a second coil that detect vibration of the flow tube 1." The vibrator thin-film coil 4 is an example of a "third coil that excites the flow tube 1." At least one of the first coil, the second coil, and the third coil is a thin-film pattern coil. Furthermore, in the Coriolis flowmeter according to this embodiment, the first coil, the second coil, and the third coil are all thin-film pattern coils.

[0023] Here, the Coriolis flowmeter may have the following configurations, for example, in which at least one of the first coil, second coil, and third coil is a thin-film pattern coil. The Coriolis flowmeter may have a configuration in which the first coil and the second coil are thin-film pattern coils, and the third coil is other than a thin-film pattern coil. Furthermore, the Coriolis flowmeter may have a configuration in which the third coil is a thin-film pattern coil, and the first coil and the second coil are other than a thin-film pattern coil.

[0024] Fig. 3 is an enlarged view of a pickup thin-film coil. While Fig. 3 shows a pickup thin-film coil 3a as an example, a pickup thin-film coil 3b has a similar structure. In this embodiment, the vibrator thin-film coil 4 also has a similar structure to the pickup thin-film coil 3a. However, the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 do not necessarily have to have the same dimensions or number of spirals.

[0025] The pickup thin-film coil 3a is fabricated, for example, as a multilayer FPC (Flexible Printed Circuit) and bonded to the flow tube 1. The insulating layer 3c is fabricated, for example, from a polyimide film or the like, and insulates the spiral thin-film coil 3d, which has a spiral shape and is formed by etching using a resist, from the flow tube 1 or the outside. The conductor ends 3e and 3f of the spiral thin-film coil 3d are connected to a signal converter (not shown) via lead wires or the like. If necessary, the lead wires used here can be included in the multilayer FPC, just like the pickup thin-film coil 3a. Furthermore, the pickup thin-film coil 3a may have a multilayer structure, increasing the number of coil turns and enhancing detection sensitivity and excitation force. In other words, the thin-film pattern coil according to this embodiment is a flexible printed circuit board printed on the surface of the flow tube 1.

[0026] Furthermore, in this embodiment, the pickup thin-film coil 3a is bonded to the flow tube 1, but the pickup thin-film coil 3a may be formed by thin-film deposition on the flow tube 1. When thin-film deposition is used, the pickup thin-film coil 3a is produced by the following procedure. The insulating layer 3c is an insulating paint pattern that prevents electrical conduction between the metal flow tube 1 and the spiral thin-film coil 3d. The insulating paint pattern can also be a seal made of insulating material. The spiral thin-film coil 3d is then disposed by deposition on the insulating layer 3c. Applying insulating paint to the surface is effective in preventing electrical conduction from the outside and ensuring durability. In this way, the thin-film pattern coil according to this embodiment can be wiring formed by deposition on the surface of the flow tube 1.

[0027] 1, in the detection unit 100, a magnet 5a is disposed at a position facing the pickup thin-film coil 3a provided in the flow tube 1. A magnet 5b is disposed at a position facing the pickup thin-film coil 3b provided in the flow tube 1. A magnet 6 is disposed at a position facing the vibrator thin-film coil 4. The magnets 5a, 5b, and 6 are held and fixed to the housing by, for example, a housing surrounding the detection unit 100 or a magnet holder attached to the housing. The mechanism for holding the magnets 5a, 5b, and 6, such as the housing and the magnetic holder, is not shown in FIG.

[0028] When the flow tube 1 is stationary, the magnets 5a, 5b, and 6 are positioned so that their central axes coincide with and are close to the opposing pickup thin-film coils 3a and 3b and vibrator thin-film coil 4. The orientation of the magnetic poles of the magnets 5a, 5b, and 6 is not important, as long as mutual magnetic interaction is not taken into consideration. However, because it is necessary to obtain a phase difference between the two induced electromotive force waveforms between the pickup thin-film coil 3a and magnet 5a, and the pickup thin-film coil 3b and magnet 5b, the magnets 5a and 5b are positioned with their magnetic poles aligned unless there is a special reason not to. Furthermore, because the magnets 5a, 5b, and 6 are close to the flow tube 1 and are therefore susceptible to the temperature effects of the fluid, it is preferable to use samarium-cobalt magnets.

[0029] 4 is a diagram showing the wiring between the thin-film pattern coils and the signal converter. The signal converter has a calculation unit 20 that determines the phase difference between the signal waveforms obtained from the pickup thin-film coils 3a and 3b and calculates the mass flow rate from the determined phase difference. The pickup thin-film coil 3a is connected to the calculation unit 20 by a pickup signal wiring 21a. The pickup thin-film coil 3b is connected to the calculation unit 20 by a pickup signal wiring 21b. The vibrator thin-film coil 4 is also connected to the calculation unit 20 by a vibrator signal wiring 22.

[0030] (Coriolis flowmeter operation) Next, an overview of the operation of a Coriolis flowmeter having a detection unit 100 will be described. The calculation unit 20 applies an AC current to the vibrator thin-film coil 4. The frequency of the AC current is preferably set to a value corresponding to the resonant frequency of the flow tube 1. In response to the applied AC current, a magnetic field is generated in the vibrator thin-film coil 4 in the z-axis direction. This magnetic field reacts with the magnetic field of the magnet 6, causing repeated repulsion and attraction, causing the flow tube 1 to vibrate in the z-axis direction. When fluid flows through the vibrating flow tube 1, the Coriolis force causes the pickup thin-film coils 3a and 3b to vibrate with different phases. This vibration changes the proximity of the pickup thin-film coils 3a and 3b to their respective paired magnets 5a and 5b, changing the amount of magnetic flux linkage generated by the magnets 5a and 5b to the pickup thin-film coils 3a and 3b. The change in the amount of magnetic flux linkage generates an induced electromotive force in the pickup thin-film coils 3a and 3b.

[0031] The calculation unit 20 acquires signal waveforms corresponding to the amplitude velocity of the flow tube 1 at the positions of the pickup thin-film coils 3a and 3b based on the induced electromotive forces of the pickup thin-film coils 3a and 3b. The signal frequency acquired by the calculation unit 20 is the same as the excitation frequency of the flow tube 1. Because the phases of the signal waveforms generated by the pickup thin-film coils 3a and 3b correlate with the mass flow rate, the calculation unit 20 calculates the phase difference between the signal waveforms. The calculation unit 20 then calculates the mass flow rate of the measured fluid using the calculated phase difference.

[0032] In this way, the calculation unit 20 applies a current to the third coil, and the force generated between the third coil and the third magnet excites the flow tube 1. The calculation unit 20 then acquires signal waveforms corresponding to the amplitude speeds based on the induced electromotive force between the first coil and the first magnet and the induced electromotive force between the second coil and the second magnet, and calculates the mass flow rate of the measured fluid based on the phase difference between the signal waveforms.

[0033] 5 is a diagram showing the operation of acquiring a pickup signal according to the first embodiment. Fig. 5 shows states 101 to 105 of the pickup thin-film coil 3a and magnet 5a arranged in the flow tube 1 in the detection unit 100 over time. Here, the excitation period of the flow tube 1 is assumed to be T. In this case, the magnetic pole of the magnet 5a is oriented in magnetic pole direction M1.

[0034] State 101 shows the state of the detection unit 100 at reference time 0. State 102 shows the state of the detection unit 100 in the period from time 0 to 4 / T. State 103 shows the state of the detection unit 100 at time T / 4. State 104 shows the state of the detection unit 100 in the period from time T / 4 to T / 2. State 105 shows the state of the detection unit 100 at time T / 2. Here, the pickup thin-film coil 3a and the magnet 5a are arranged facing each other in the z-axis direction, and the negative direction of the z-axis is the magnetic pole direction of the magnet 5a.

[0035] In this embodiment, the flow tube 1 vibrates in the z-axis direction, that is, the pickup thin-film coil 3 repeatedly moves away from and toward the magnet 5a in the normal direction of the surface facing the magnet 5a.

[0036] At time 0, shown in state 101, the flow tube 1 has zero amplitude and corresponds to its unexcited position. In state 101, the flow tube 1 moves in the direction away from the magnet 5a, as indicated by arrow Q1.

[0037] In the period from time 0 to time T / 4 shown in state 102, the amount of magnetic flux linkage penetrating the pickup thin-film coil 3a decreases due to the excitation of the flow tube 1. In this case, an induced electromotive force is generated in the pickup thin-film coil 3a to compensate for the decreasing amount of magnetic flux linkage. Therefore, a coil current flows in the pickup thin-film coil 3a in the direction of arrow P1.

[0038] At time T / 4 shown in state 103, the flow tube 1 is at the maximum amplitude and the amplitude speed is 0. In state 103, there is no change in the amount of magnetic flux linkage, so no induced electromotive force is generated.

[0039] Thereafter, the flow tube 1 moves in the direction indicated by arrow Q2, approaching the magnet 5a. In the period from time T / 4 to time T / 2 indicated in state 104, the flow tube 1 moves in the direction indicated by arrow Q2. In state 104, the amount of magnetic flux linkage to the pickup thin-film coil 3a increases. In this case, an induced electromotive force is generated in a direction that generates magnetic flux in the opposite direction. Therefore, a coil current flows in the pickup thin-film coil 3a in the direction indicated by arrow P2.

[0040] At time T / 2 shown in state 105, the flow tube 1 reaches its maximum amplitude velocity and continues to move in the direction toward the magnet 5a indicated by arrow Q2. In this case, the amount of magnetic flux linkage to the pickup thin-film coil 3a continues to increase, and an induced electromotive force is generated in a direction that generates magnetic flux in the opposite direction. Therefore, even in state 105, a coil current flows through the pickup thin-film coil 3a in the direction indicated by arrow P2.

[0041] Thereafter, the flow tube 1 oscillates in the direction opposite to that of states 101 to 105, approaches the magnet 5a until the amplitude reaches a maximum, and then returns to the same state as state 101. During this time, the coil current generated in the pickup thin-film coil 3a flows in the direction opposite to that of states 101 to 105. The above operation is similar for the pickup thin-film coil 3b and the magnet 5b.

[0042] In the arrangement shown in Fig. 5, the current signal increases and decreases over a 1 / 2 cycle until time T / 2. Therefore, in the arrangement shown in Fig. 5, the signal waveform extracted by the pickup thin-film coil 3a has the same frequency as the flow tube 1. Note that in Fig. 5, the displacement of the flow tube 1 relative to the magnet 5a is exaggerated for the sake of explanation, but in reality, the displacement is on the order of submicrons to microns.

[0043] [effect] As described above, in the Coriolis flowmeter according to this embodiment, the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 are disposed on the surface of the flow tube 1. The flow tube 1 is excited by applying an AC current to the vibrator thin-film coil 4, and the calculation unit 20 calculates the mass flow rate based on a signal waveform due to the induced electromotive force generated by the pickup thin-film coils 3a and 3b and the magnets 5a and 5b.

[0044] The pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4, which are thin-film pattern coils, are light in weight relative to the flow tube 1, so any changes in vibration characteristics due to their weight are negligible. Therefore, a mass balance adjustment process for sensors attached to the flow tube 1 is unnecessary. Furthermore, conventional Coriolis flowmeters have a structure in which pickup sensors and vibrator sensors, including wound coils, are attached to the flow tube or the housing. In contrast, the Coriolis flowmeter of this embodiment employs thin-film pattern coils, thereby eliminating the need for wound coils and bobbin components such as coil bobbins and coil bobbin holders. This eliminates the need to fabricate components to attach them to the flow tube 1, thereby reducing the number of components. Furthermore, by eliminating the components other than the thin-film pattern coils from the flow tube 1, the need for bonding these components to the flow tube 1, such as welding or brazing, is eliminated. Therefore, the Coriolis flowmeter of this embodiment is easy to manufacture.

[0045] In the above embodiment, the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 are both thin-film pattern coils. However, one or two of these coils may be formed as thin-film pattern coils. Even in this case, the number of winding coils and bobbin components, such as the coil bobbin and coil bobbin holder, for at least the coils can be reduced. This eliminates the need to fabricate components for attaching these components to the flow tube, thereby reducing the number of components. Furthermore, the need for bonding these components to the flow tube, such as welding or brazing, is eliminated. Therefore, even if one or two of the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 are formed as thin-film pattern coils, the Coriolis flowmeter can be easily manufactured.

[0046] (Second embodiment) 6 is a perspective view of a detection unit in a Coriolis flowmeter according to the second embodiment. In the Coriolis flowmeter according to this embodiment, the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 are arranged on the same line in the flow path direction, but the vibrator thin-film coil 4 is rotated a predetermined degree around the flow path direction as an axis. FIG. 6 shows, as an example, a case where the vibrator thin-film coil 4 is rotated 90 degrees around the flow path direction as an axis relative to the pickup thin-film coils 3a and 3b.

[0047] That is, in the Coriolis flowmeter according to this embodiment, the first coil and the second coil are arranged side by side on the surface of the flow tube 1 in the flow path direction, and the third coil is arranged at a position spaced a predetermined angle from the position where the first coil and the second coil are arranged side by side in the direction of rotation about the flow path.

[0048] 6, an excitation force in the y-axis direction is generated by the excitation thin-film coil 4 and the magnet 6. Therefore, the flow tube 1 is excited to vibrate in the y-axis direction, unlike the first embodiment.

[0049] Fig. 7 is a diagram showing the operation of acquiring a pickup signal according to the second embodiment. Fig. 7 is a diagram showing the pickup thin-film coil 3a viewed from the magnet 5a side with the magnet 5a in place. Fig. 7 shows states 111 to 115 of the pickup thin-film coil 3a and magnet 5a arranged in the flow tube 1 in the detection unit 100 over time. Here, the excitation period of the flow tube 1 is assumed to be T for the explanation.

[0050] State 111 shows the state of the detection unit 100 at reference time 0. State 112 shows the state of the detection unit 100 in the period from time 0 to 4 / T. State 113 shows the state of the detection unit 100 at time T / 4. State 114 shows the state of the detection unit 100 in the period from time T / 4 to T / 2. State 115 shows the state of the detection unit 100 at time T / 2. Here, the pickup thin-film coil 3a and the magnet 5a are arranged facing each other in the z-axis direction.

[0051] In this case, the flow tube 1 vibrates in the y-axis direction. That is, the pickup thin-film coil 3 repeatedly moves away from and close to the magnet 5a so that the opposing surfaces thereof pass each other.

[0052] At time 0 shown in state 111, the flow tube 1 has an amplitude of 0, which corresponds to the position of the flow tube 1 in an unexcited state. In state 111, the flow tube 1 moves in the positive y-axis direction.

[0053] In the period from time 0 to time T / 4 shown in state 112, the flow tube 1 is excited, causing movement in the direction of arrow Q3. In this case, the amount of magnetic flux linkage penetrating the pickup thin-film coil 3a decreases. An induced electromotive force is generated in the pickup thin-film coil 3a to compensate for the decreasing amount of magnetic flux linkage. As a result, a coil current flows in the pickup thin-film coil 3a in the direction of arrow P3.

[0054] At time T / 4 shown in state 113, the amplitude of the flow tube 1 reaches a maximum and the amplitude speed becomes 0. In state 113, there is no change in the amount of interlinkage magnetic flux, so no induced electromotive force is generated.

[0055] Thereafter, the flow tube 1 moves in the direction indicated by arrow Q4. In the period from time T / 4 to time T / 2 indicated by state 114, the amount of magnetic flux linkage to the pickup thin-film coil 3a increases. In this case, an induced electromotive force is generated in a direction that generates magnetic flux in the opposite direction. Therefore, a coil current flows in the pickup thin-film coil 3a in the direction indicated by arrow P4.

[0056] At time T / 2 shown in state 115, the amplitude speed of the flow tube 1 is at its maximum, but the amount of interlinked magnetic flux switches between increasing and decreasing, so the induced electromotive force becomes zero.

[0057] 7, the current signal increases and decreases for one cycle up to time T / 2. Therefore, in the arrangement of FIG. 7, the signal waveform extracted by the pickup thin-film coil 3a has a frequency twice that of the flow tube 1.

[0058] [effect] As described above, in the Coriolis flowmeter according to this embodiment, the pickup thin-film coils 3a and 3b are arranged in the flow path direction on the surface of the flow tube 1. The vibrator thin-film coil 4 is arranged at a position rotated a predetermined degree around the axis of the flow path direction relative to the arrangement of the pickup thin-film coils 3a and 3b on the surface of the flow tube 1.

[0059] In this way, the mass flow rate can be calculated even if the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 are not aligned in a row. Therefore, even if there are restrictions on the placement of the magnets 5a, 5b, 6, etc., they can be placed in appropriate positions according to the restrictions, and a Coriolis flowmeter that meets the placement restrictions can be easily manufactured.

[0060] (Third embodiment) 8 is a perspective view of a detection unit in a Coriolis flowmeter according to the third embodiment. In the Coriolis flowmeter according to this embodiment, pickup thin-film coils 7a and 7b and a vibrator thin-film coil 8 are arranged on the surface of a flow tube 1.

[0061] The pickup thin-film coil 7a has two spiral thin-film coils 711 and 712. The spiral thin-film coils 711 and 712 are arranged at opposing positions on the surface of the flow tube 1, and their centers are on a straight line that passes through the center of the cross section of the flow tube 1. In other words, the spiral thin-film coils 711 and 712 have the same central axis. In this way, the thin-film pattern coil according to this embodiment has two spiral thin-film coils 711 and 712 with the same central axis.

[0062] Similarly, the pickup thin-film coil 7b has two spiral thin-film coils 721 and 722. Similarly, the vibrator thin-film coil 8 has two spiral thin-film coils 81 and .

[0063] Fig. 9 is an enlarged view of a portion of the pickup thin-film coil according to the third embodiment. Fig. 9 shows the flow tube 1 in which the pickup thin-film coil 7a is disposed, viewed from the negative direction of the y-axis. The pickup thin-film coil 7a has a thin-film conductor 713 connecting two spiral thin-film coils 711 and 712. The spiral thin-film coils 711 and 712 and the thin-film conductor 713 are formed as a single conductor path on an insulating layer 714.

[0064] FIG. 10 is a simplified diagram of a pickup thin-film coil according to the third embodiment. When viewed from the positive direction of the z-axis, the two spiral thin-film coils 711 and 712 have opposite spiral directions. However, when a voltage is generated between the conductor end 715 and the conductor end 716, the spiral directions of current flow in the spiral thin-film coils 711 and 712 are the same. For example, when the voltage at the conductor end 715 is higher than the voltage at the conductor end 716, a current flows counterclockwise in the spiral thin-film coil 711. Similarly, a current flows counterclockwise in the spiral thin-film coil 712. The pickup thin-film coil 7b and the vibrator thin-film coil 8 have the same configuration.

[0065] Fig. 11 is a plan view of a detector according to the third embodiment. In a detection unit 100 according to the third embodiment, two magnets 9a, 9b, and 10 are arranged relative to the pickup thin-film coils 7a and 7b and the vibrator thin-film coil 8. The magnetic poles of the magnets 9a, 9b, and 10 are arranged such that, for each of the two opposing magnets 9a, 9b, and 10, the magnetic pole directions M11 and M12 are opposite poles, the magnetic pole directions M21 and M22 are opposite poles, and the magnetic pole directions M31 and M32 are opposite poles, as shown in Fig. 11.

[0066] 12 is a diagram showing the operation of the vibrator according to the third embodiment. In this case, the vibrator thin-film coil 8 has spiral thin-film coils 81 and 82, a thin-film conductor 83, and conductor end portions 84 and 85. The spiral thin-film coil 81 and the spiral thin-film coil 82 are connected by the thin-film conductor 83.

[0067] The following description will be given assuming that a current is applied flowing from the conductor end 84 to the conductor end 85, as indicated by arrows P5 and P6. In this case, a magnetic field is generated in the spiral thin-film coil 81 in the positive direction of the z-axis. The magnetic field in the positive direction of the z-axis generated by the spiral thin-film coil 81 and the magnetic field in the positive direction of the z-axis generated by the magnet 10 interact to produce an attractive force, which causes the flow tube 1 to receive a force in the negative direction of the z-axis, as indicated by arrow Q5. A magnetic field is also generated in the spiral thin-film coil 82 in the positive direction of the z-axis. The magnetic field in the positive direction of the z-axis generated by the spiral thin-film coil 82 interacts with the magnetic field in the negative direction of the z-axis generated by the magnet 10, which causes a repulsive force, which causes the flow tube 1 to receive a force in the negative direction of the z-axis, as indicated by arrow Q5. Therefore, compared to the configuration having one spiral thin-film coil shown in the first embodiment, the Coriolis flowmeter of this embodiment can obtain twice the excitation force at the same current value.

[0068] FIG. 13 is a diagram showing the operation of the third embodiment when acquiring a pickup signal. The diagram shows the pickup thin-film coil 7a and magnet 9a during the period from time 0 to time T / 2, where T is the excitation period of the tube. For the sake of explanation, FIG. 13 exaggerates the displacement of the flow tube 1 relative to the magnet 9a, but in reality, the displacement is on the order of submicrons to microns. FIG. 13 shows the flow tube 1 as viewed from the positive y-axis direction, with two spiral thin-film coils 711 and 712 connected by a thin-film conductor 713 on the back side of the flow tube 1.

[0069] State 121 indicates the state of detection unit 100 at reference time 0. State 122 indicates the state of detection unit 100 in the interval from time 0 to 4 / T. State 123 indicates the state of detection unit 100 at time T / 4. State 124 indicates the state of detection unit 100 in the interval from time T / 4 to T / 2. State 125 indicates the state of detection unit 100 at time T / 2.

[0070] In this case, the flow tube 1 vibrates in the z-axis direction. That is, the pickup thin-film coil 3 repeatedly moves away from and toward the magnet 5a in the normal direction of the surface facing the magnet 5a.

[0071] In state 121 at time 0, flow tube 1 corresponds to a position where the amplitude is 0 and the flow tube is not excited. In state 121, flow tube 1 moves in a direction toward magnetic pole direction M11.

[0072] During the period from time 0 to time T / 4 shown in state 122, the flow tube 1 moves in the positive direction of the z-axis, as indicated by arrow Q6, increasing the amount of magnetic flux linkage in the positive direction of the z-axis of the spiral thin-film coil 711. Consequently, an induced electromotive force is generated in the spiral thin-film coil 711, generating magnetic flux in the negative direction of the z-axis. As a result, a current flows through the spiral thin-film coil 711 in the direction indicated by arrow P6, from the conductor end 716 to the conductor end 715. Furthermore, the amount of magnetic flux linkage in the negative direction of the z-axis of the spiral thin-film coil 712 decreases. Consequently, an induced electromotive force is generated in the spiral thin-film coil 712, generating magnetic flux in the negative direction of the z-axis. As a result, a current flows through the spiral thin-film coil 712 in the direction indicated by arrow P7, from the conductor end 716 to the conductor end 715. In this case, the Coriolis flowmeter according to this embodiment generates an electromotive force that is twice as large as the one having one spiral thin-film coil shown in the first embodiment. This improves the S / N ratio against noise such as disturbances.

[0073] Then, at time T / 4 shown in state 123, the amplitude of the flow tube 1 reaches a maximum and the amplitude speed becomes 0. In state 123, there is no change in the amount of interlinkage magnetic flux, so no induced electromotive force is generated.

[0074] During the period from time T / 4 to time T / 2 shown in state 124, the flow tube 1 moves in the negative z-axis direction, as indicated by arrow Q7, reducing the amount of magnetic flux linking the spiral thin-film coil 711 in the positive z-axis direction. This generates an induced electromotive force in the spiral thin-film coil 711, generating magnetic flux in the positive z-axis direction. Current flows through the spiral thin-film coil 711 in the direction indicated by arrow P8, from the conductor end 715 to the conductor end 716. Furthermore, the amount of magnetic flux linking the spiral thin-film coil 712 in the negative z-axis direction increases. This generates an induced electromotive force in the spiral thin-film coil 712, generating magnetic flux in the positive z-axis direction. Current flows through the spiral thin-film coil 712 in the direction indicated by arrow P9, from the conductor end 715 to the conductor end 716. In this case, the Coriolis flowmeter according to this embodiment generates an electromotive force twice as large as the one obtained in the first embodiment, using a single spiral thin-film coil. This improves the S / N ratio against noise such as disturbances.

[0075] At time T / 2 shown in state 125, the amplitude velocity of the flow tube 1 in the direction of the arrow 7 reaches a maximum, and the change in the amount of magnetic flux linkage also reaches a maximum. As a result, the induced electromotive force reaches a maximum value at time T / 2.

[0076] In the arrangement of FIG. 13, the current signal increases and decreases over a 1 / 2 cycle until time T / 2. Therefore, in the arrangement of FIG. 13, the signal waveform extracted by the pickup thin-film coil 3a has the same frequency as that of the flow tube 1. The above operation is similar for the pickup thin-film coil 7b and the magnet 9b. The above explanation has been given using an example in which the magnetic poles of the two magnets 9a are in the negative x-axis direction, but the same effect can be achieved by changing the magnetic poles of both magnets 9a to be in the positive x-axis direction. For example, if the spiral direction of the spiral thin-film coil 711 and the spiral direction of the spiral thin-film coil 711 are opposite, the same effect can be achieved by changing the magnetic poles of the magnets 9a and 9b.

[0077] [effect] As described above, the Coriolis flowmeter according to this embodiment is provided with the pickup thin-film coil 7a having the spiral thin-film coils 711 and 712 on the surface of the flow tube 1, and the pickup thin-film coil 7b having the spiral thin-film coils 721 and 722. Furthermore, the vibrator thin-film coil 8 having the spiral thin-film coils 81 and 82 is provided on the surface of the flow tube 1. In the Coriolis flowmeter according to this embodiment, the vibrator thin-film coil 8 excites the flow tube 1, and signal waveforms are obtained by the pickup thin-film coils 7a and 7b.

[0078] In this way, by using the vibrator thin-film coil 8 having two spiral thin-film coils 81 and 82, it is possible to obtain twice the excitation force with the same current value compared to a configuration using one spiral thin-film coil. Also, by using the pickup thin-film coil 7a having two spiral thin-film coils 711 and 712, it is possible to obtain twice the electromotive force compared to a configuration using one spiral thin-film coil. As a result, the S / N ratio against noise such as disturbances is improved.

[0079] (Fourth embodiment) 14 is a plan view of a detection unit in a Coriolis flowmeter according to the fourth embodiment. As shown in FIG. 14, the detection unit 100 according to this embodiment includes pickup thin-film coils 7a and 7b, each of which has two spiral thin-film coil regions, and a vibrator thin-film coil 8.

[0080] The pickup thin-film coils 7a and 7b are arranged in a row in the flow path direction on the surface of the flow tube 1. The vibrator thin-film coil 8 is arranged on the surface of the flow tube 1 at a position rotated by a predetermined angle from the position where the pickup thin-film coils 7a and 7b are arranged with respect to the flow path axis of the flow tube 1. In this embodiment, the vibrator thin-film coil 8 is arranged at a position rotated by 90 degrees from the position where the pickup thin-film coils 7a and 7b are arranged with respect to the flow path axis of the flow tube 1.

[0081] In the case of Figure 14, when a current is applied to the vibrator thin-film coil 8, the flow tube 1 is excited in the y-axis direction. Therefore, the two magnets 9a arranged relative to the pickup thin-film coil 7a are arranged so that their magnetic poles face the same direction. The same applies to magnet 9b. The two magnets 10 arranged relative to the vibrator thin-film coil 8 are arranged so that their magnetic poles face opposite directions. In this case, too, the electrical signal generated by the pickup thin-film coils 7a and 7b has twice the electromotive force and a frequency twice the amplitude of the flow tube 1 compared to a structure having only one spiral thin-film coil.

[0082] [effect] In the Coriolis flowmeter according to this embodiment, an angle in the direction of rotation about the flow path is formed between the aligned positions of the pickup thin-film coils 7a and 7b and the vibrator thin-film coil 8. Therefore, even if there are restrictions on the placement of the magnets 9a, 9b, 10, etc., it is possible to easily manufacture a Coriolis flowmeter that improves the excitation force and the S / N ratio for noise in accordance with the restrictions.

[0083] (Fifth embodiment) 15 is a perspective view of a detection unit in a Coriolis flowmeter according to a fifth embodiment. The detection unit 100 according to this embodiment has two flow tubes 1a and 1b, each having two bends. Both flow tubes 1a and 1b are bent symmetrically into a U-shape. The flow tubes 1a and 1b are arranged side by side so that their flow paths are parallel. Furthermore, flanges 2a and 2b are connected to both ends of the flow tubes 1a and 1b in the flow path direction, respectively.

[0084] The flow tube 1a has a vibrator thin-film coil 202 at the center of the surface facing the flow tube 1b. The flow tube 1a also has magnets 201a and 201b at positions symmetrical with respect to the vibrator thin-film coil 202 on the surface facing the flow tube 1b.

[0085] Flow tube 1b has magnet 204 at the center of the surface facing flow tube 1a, facing vibrator thin-film coil 202. Flow tube 1b also has pickup thin-film coil 203a at a position facing magnet 201a, which is located at an symmetrical position with respect to magnet 204 on the surface facing flow tube 1a, and pickup thin-film coil 203b at a position facing magnet 201b.

[0086] The calculation unit 20 applies a current to the vibrator thin-film coil 202, and excites the flow tubes 1a and 1b in the z direction shown in the drawing by the action of the magnetic field of the magnet 204. The calculation unit 20 then acquires signal waveforms due to the induced electromotive forces between the pickup thin-film coil 203a and the magnet 201a and between the pickup thin-film coil 203b and the magnet 201b, and calculates the mass flow rate using the phase difference between the signal waveforms.

[0087] (effect) The Coriolis flowmeter according to this embodiment has two bent flow tubes 1a and 1b. Thus, even in a Coriolis flowmeter using bent flow tubes 1a and 1b, the mass flow rate can be calculated using a thin-film patterned coil. Therefore, a Coriolis flowmeter using bent flow tubes 1a and 1b can be easily manufactured. Furthermore, although this embodiment has been described with reference to a case where two flow tubes 1a and 1b are included, even in a case where a flow tube 1a has one bend, for example, the mass flow rate can be calculated using a thin-film patterned coil and the flowmeter can be easily manufactured.

[0088] (Variation) The calculation unit 20 can calculate the excitation frequency of the flow tube 1 from the signal waveform obtained by the pickup thin-film coils 3a and 3b of the first embodiment, for example. There is a correlation between the density of the fluid flowing through the flow tube 1 and the excitation frequency of the flow tube 1 containing the fluid. Therefore, the calculation unit 20 can measure the fluid density based on the calculated excitation frequency of the flow tube 1. This configuration can be applied to any of the second to fourth embodiments. In this way, the Coriolis flowmeter of this modification can be used not only for flow rate measurement but also as a density measurement device.

[0089] In this way, the calculation unit 20 applies a current to the third coil, and the force generated between the third coil and the third magnet excites the flow tube 1. Then, the calculation unit 20 acquires signal waveforms corresponding to the amplitude speeds based on the induced electromotive force between the first coil and the first magnet and the induced electromotive force between the second coil and the second magnet, calculates the excitation frequency of the flow tube 1 based on the signal waveforms, and calculates the density of the measured fluid based on the calculated excitation frequency.

[0090] Furthermore, for example, the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 attached to the flow tube 1 of the first embodiment are in direct contact with the flow tube 1, and therefore reach a temperature equivalent to the fluid temperature. There is a correlation between the resistance values ​​of the metals used in the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 and the object temperature. Therefore, the calculation unit 20 can calculate the change in resistivity of the pickup thin-film coils 3a and 3b and the vibrator thin-film coil 4 and measure the temperature of the fluid using the calculated resistance change. This configuration can be applied to any of the second to fourth embodiments. In this way, the Coriolis flowmeter according to this modification can be used as a temperature sensor.

[0091] In this way, the calculation unit 20 acquires the resistance value of the first coil, the second coil, or the third coil, and calculates the temperature of the fluid to be measured based on the resistance value.

[0092] Some examples of combinations of the disclosed technical features are set out below. (1) a flow tube through which a measurement fluid flows; a first coil and a second coil disposed on a surface of the flow tube, at least one of which is a thin film pattern coil, for detecting vibration of the flow tube, and a third coil for exciting vibration of the flow tube; a first magnet provided at a position facing the first coil and a second magnet provided at a position facing the second coil; a third magnet provided at a position facing the third coil; A Coriolis flowmeter comprising: (2) The Coriolis flowmeter according to (1), wherein the first coil, the second coil, and the third coil are all thin film pattern coils. (3) The Coriolis flowmeter according to (1) or (2), wherein the thin film pattern coil is a flexible printed circuit board printed on the surface of the flow tube. (4) The Coriolis flowmeter according to any one of (1) to (3), wherein the thin film pattern coil is a wiring formed by vapor deposition on the surface of a flow tube. (5) The Coriolis flowmeter according to any one of (1) to (4), wherein the thin film pattern coil has a plurality of laminated thin film patterns. (6) the first coil and the second coil are arranged on a surface of the flow tube in a flow direction of the measurement fluid flowing through the flow tube, The third coil is disposed at a position spaced a predetermined angle from the position where the first coil and the second coil are aligned in a rotation direction about the flow path of the measurement fluid. The Coriolis flowmeter according to any one of (1) to (5). (7) The Coriolis flowmeter according to any one of (1) to (6), wherein the thin film pattern coil has two spiral thin film coils whose central axes coincide with each other. (8) The Coriolis flowmeter according to any one of (1) to (7), further comprising a calculation unit that applies a current to the third coil to excite the flow tube by a force generated between the third coil and the third magnet, acquires signal waveforms corresponding to the amplitude speeds based on the induced electromotive forces between the first coil and the first magnet and the induced electromotive forces between the second coil and the second magnet, and calculates the mass flow rate of the measured fluid based on a phase difference between the signal waveforms. (9) The Coriolis flowmeter according to any one of (1) to (7), further comprising a calculation unit that applies a current to the third coil to excite the flow tube by a force generated between the third coil and the third magnet, obtains signal waveforms corresponding to the amplitude speeds based on the induced electromotive forces between the first coil and the first magnet and the induced electromotive forces between the second coil and the second magnet, calculates an excitation frequency of the flow tube based on the signal waveforms, and calculates the density of the measured fluid based on the calculated excitation frequency. (10) The Coriolis flowmeter according to any one of (1) to (9), further comprising a calculation unit that acquires a resistance value of at least one of the first coil, the second coil, or the third coil, and calculates a temperature of the measured fluid based on the resistance value. [Explanation of symbols]

[0093] 1 flow tube 2a, 2b flange 3a, 3b Pickup thin film coil 3c Insulation layer 3D spiral thin film coil 3e,3f Conductor end 4. Vibrator thin film coil 5a,5b,6 magnet 7a, 7b Pickup thin film coil 8. Vibrator thin film coil 9a,9b,10 magnet 81,82,711,712,721,722 Spiral thin film coil 83,713 Thin film conductor 84,85,715,716 Conductor end 20 Arithmetic section 21a, 21b Pickup signal wiring 22 Vibrator signal wiring 100 Detector 1a, 1b Flow tube 201a, 201b, 204 Magnets 202 Vibrator Thin Film Coil 203a, 203b Pickup thin film coil 714 Insulation Layer

Claims

1. a flow tube through which a measurement fluid flows; a first coil and a second coil disposed on a surface of the flow tube, at least one of which is a thin film pattern coil, for detecting vibration of the flow tube, and a third coil for exciting vibration of the flow tube; a first magnet provided at a position facing the first coil and a second magnet provided at a position facing the second coil; a third magnet provided at a position facing the third coil; A Coriolis flowmeter comprising:

2. 2. The Coriolis flowmeter according to claim 1, wherein the first coil, the second coil, and the third coil are all thin film pattern coils.

3. 2. The Coriolis flowmeter according to claim 1, wherein the thin film pattern coil is a flexible printed circuit board printed on the surface of the flow tube.

4. 2. The Coriolis flowmeter according to claim 1, wherein the thin film pattern coil is a wiring formed by vapor deposition on the surface of the flow tube.

5. 2. The Coriolis flowmeter according to claim 1, wherein the thin film pattern coil has a plurality of laminated thin film patterns.

6. the first coil and the second coil are arranged on a surface of the flow tube in a flow direction of the measurement fluid flowing through the flow tube, The third coil is disposed at a position spaced a predetermined angle from the position where the first coil and the second coil are aligned in a rotation direction about the flow path of the fluid to be measured.

2. The Coriolis flowmeter according to claim 1.

7. 2. The Coriolis flowmeter according to claim 1, wherein the thin film pattern coil comprises two spiral thin film coils whose central axes coincide with each other.

8. 2. The Coriolis flowmeter according to claim 1, further comprising a calculation unit that applies a current to the third coil to excite the flow tube by a force generated between the third coil and the third magnet, obtains signal waveforms corresponding to the amplitude velocities based on an induced electromotive force between the first coil and the first magnet and an induced electromotive force between the second coil and the second magnet, and calculates a mass flow rate of the measured fluid based on a phase difference between the signal waveforms.

9. 2. The Coriolis flowmeter according to claim 1, further comprising a calculation unit that applies a current to the third coil to excite the flow tube by a force generated between the third coil and the third magnet, obtains signal waveforms corresponding to the amplitude speeds based on the induced electromotive forces between the first coil and the first magnet and the induced electromotive forces between the second coil and the second magnet, calculates an excitation frequency of the flow tube based on the signal waveforms, and calculates the density of the measured fluid based on the calculated excitation frequency.

10. 2. The Coriolis flowmeter according to claim 1, further comprising a calculation unit that acquires a resistance value of at least one of the first coil, the second coil, and the third coil, and calculates a temperature of the measured fluid based on the resistance value.

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