JP3907637B2 - Circle type single tube Coriolis flow meter - Google Patents

Description

  The present invention relates to a Coriolis flow meter, and more particularly, to a circle type single tube Coriolis flow meter in which an intermediate portion of one flow tube for flowing a fluid to be measured is formed in a circle shape.

  The Coriolis flowmeter supports one or both ends of the flow tube (flow tube) through which the fluid to be measured flows, and when a vibration is applied around the support point in a direction perpendicular to the flow direction of the flow tube, This is a mass flow meter utilizing the fact that the Coriolis force acting is proportional to the mass flow rate. Coriolis flowmeters are well known, and the shape of the flow tube in the Coriolis flowmeter is roughly divided into a straight tube type and a curved tube type.

  The straight pipe type Coriolis flowmeter is a straight pipe that is supported by the Coriolis force between the straight pipe support section and the center section when vibration is applied in the direction perpendicular to the straight pipe axis of the straight pipe center supported at both ends. A displacement difference of the tube, that is, a phase difference signal is obtained, and the mass flow rate is detected based on the phase difference signal. Such a straight tube type Coriolis flowmeter has a simple, compact and robust structure. However, it also has a problem that high detection sensitivity cannot be obtained.

On the other hand, the curved tube type Coriolis flow meter is superior to the straight tube type Coriolis flow meter in that it can select the shape to effectively extract the Coriolis force. Can be detected. In addition, as a curved tube type Coriolis flowmeter, one flow tube is formed in a gate shape (for example, refer to Patent Document 1), or a middle portion of one flow tube is formed in a circle shape. (See, for example, Patent Document 2).
Japanese Examined Patent Publication No. 4-55250 Japanese Patent No. 2557098

  By the way, in the prior art of the said patent document 1, since it becomes a structure where the drive device for vibrating a flow tube is fixed to the rigid body parallel to a flow tube, it is the flow tube by the heat | fever of the fluid to be measured. When the heat expands, a positional shift occurs with the drive device due to the heat expansion, which affects the output. On the other hand, in the prior art of the above-mentioned Patent Document 2, since the driving device is arranged between one end and the other end of the circle-shaped intermediate portion, it is effective in solving the above problems. Conceivable. However, when a single flow tube having an intermediate portion formed in a circle shape is used, there is a problem that the vibration frequency is not stable.

  This invention is made | formed in view of the situation mentioned above, and makes it a subject to provide the circle type single tube Coriolis flowmeter which can aim at stabilization of a vibration frequency.

The circle type single tube Coriolis flow meter according to the present invention according to claim 1, which has been made to solve the above-mentioned problems, includes a single flow tube for flowing a fluid to be measured, a driving means for driving the flow tube, and the flow Rutotomoni and detecting means for detecting a phase difference proportional to a Coriolis force acting on the tube, the a single tube Coriolis flowmeter comprising a connecting member for connecting the flow tube and the rigid, said flow tube A circle-shaped intermediate portion, an arm-shaped first arm portion extending from one end portion of the intermediate portion toward the first support portion for the flow tube, and the other end portion of the intermediate portion with respect to the flow tube And a second arm portion having an arm shape extending toward the second support portion, and the driving means is connected to the one of the intermediate portions and the other In the section above the flow tube disposed at the intersections of the secondary or circle type one which is driven by a fourth-order mode tube Coriolis flowmeter, opposite the location of said drive means, said intermediate portion of said circle shape The connecting member is provided on the top of the first axis, the axis connecting the first support part and the second support part is a first axis, the axis orthogonal to the first axis is the second axis, the first axis and the second axis When the axial direction perpendicular to the axis is the arrangement direction of the drive means and the connecting member, the intermediate portion is circumferential with respect to the arrangement direction when the drive means is driven in the secondary or quaternary mode. The coupling member is formed so that the intermediate portion cannot move in the first axial direction and is movable in the second axial direction, and the moving direction of the intermediate portion is set in such a direction. and characterized in that it functions as a member that restricts To have. According to the present invention having such a feature, in the vibration of the flow tube, the moving direction of the intermediate portion is restricted by the connecting member. By interposing the connecting member between the top portion of the intermediate portion and the rigid body, the moving direction of the flow tube can be restricted.

  The circle type single tube Coriolis flow meter of the present invention according to claim 2 is the circle type single tube Coriolis flow meter according to claim 1, wherein the lengths of the first arm portion and the second arm portion are determined. The length of the intermediate portion is the same as or longer than the length of the diameter in the first axial direction. According to the present invention having such features, the flow tube is driven at a position away from the first and second support portions.

According to the present invention described in claim 1, it is possible to regulate the movement direction of the intermediate portion in the flow tube vibration using the connecting member. Therefore, this brings about an effect that the vibration frequency can be stabilized.

  According to the second aspect of the present invention, since the distance between the first and second support portions and the driving means is increased, it is possible to prevent the occurrence of a zero shift.

Hereinafter, description will be given with reference to the drawings.
FIG. 1 is a view showing an embodiment of a circle type single tube Coriolis flow meter according to the present invention. FIG. 1A is a configuration diagram, and FIG. 1B is a perspective view of a top portion of a flow tube and a connecting member. FIG. 2 is a plan view of the flow tube.

  1 and 2, a circle type single tube Coriolis flow meter 1 (hereinafter abbreviated as Coriolis flow meter 1) of the present invention indicated by reference numeral 1 is a flow meter used for flow measurement in the fluid industry, for example. A housing 2, a single flow tube 3 housed in the housing 2, a driving device (driving means) 4 for driving the flow tube 3 in a secondary or quaternary mode, and a flow A pair of vibration detection sensors (detecting means) 5 and 5 for detecting a phase difference proportional to the Coriolis force acting on the tube 3, a connecting member 8 for connecting the top portion 6 of the flow tube 3 to the rigid body 7, and a conversion (not shown) It is mainly provided with a vessel. The Coriolis flow meter 1 of the present invention has a structure aimed at stabilizing the vibration frequency by restricting the moving direction of the flow tube 3 during vibration. Each configuration will be described below.

  The housing 2 has a structure that is strong against bending and twisting. Moreover, the housing | casing 2 is formed so that main parts of flowmeters, such as the flow tube 3, can be protected. The inside of the housing 2 is filled with an inert gas such as argon gas. By filling with the inert gas, dew condensation on the flow tube 3 and the like is prevented. Support portions (first and second support portions) 9 and 9 for supporting and fixing the inflow side and the outflow side of the flow tube 3 are attached and fixed to the housing 2. The Coriolis flowmeter 1 according to the present invention has a structure that does not amplify disturbance vibrations and hardly transmits vibrations to the flow tube 3 via the support portions 9 and 9.

  The flow tube 3 is made of a curved tube, and has a circle-shaped intermediate portion 10 and an arm-shaped first arm portion extending from one end portion of the intermediate portion 10 toward the support portion 9 on the inlet side. 11 and an arm-shaped second arm portion 12 extending from the other end of the intermediate portion 10 toward the support portion 9 on the outlet side.

  The top portion 6 of the intermediate portion 10 is connected to the rigid body 7 via the connecting member 8 (the connecting member 8 will be described later). The intermediate portion 10 is formed to have a relatively small circular shape when viewed from the front. A space is appropriately provided between the one end portion and the other end portion of the intermediate portion 10, that is, at the intersection portion 13 in order to attach the driving device 4. As a matter of course, the one end portion of the intermediate portion 10 and the first arm portion 11 are assumed to be continuously connected. In addition, the other end of the intermediate portion 10 and the second arm portion 12 are also continuously connected.

  The first arm portion 11 and the second arm portion 12 are formed relatively long in order to make it difficult for the zero point shift to occur. That is, in order to ensure a sufficient distance between the drive device 4 and the support portions 9 and 9, for example, the diameter of the intermediate portion 10 (if the axis connecting the support portions 9 and 9 is the first axis P, the diameter in the P direction) It is formed to be the same as or longer than The material of the flow tube 3 is a normal material in this technical field such as stainless steel, hastelloy, titanium alloy and the like.

  As described above, the driving device 4 is a means for driving the flow tube 3 in the secondary or quaternary mode, and is configured to include a coil and a magnet, although not particularly shown. The coil and magnet of the driving device 4 are attached to the intersecting portion 13 of the intermediate portion 10 in the flow tube 3 using a dedicated fixture. Although not particularly illustrated, an electric wire is drawn from the coil of the driving device 4. The electric wire is connected to the converter (not shown).

  When an attracting action is generated in the driving device 4, the magnet of the driving device 4 is inserted into the coil. As a result, the one end of the intermediate portion 10 and the other end are close to each other. On the other hand, when a repulsive action occurs in the drive device 4, the magnet of the drive device 4 is pushed out of the coil. As a result, the one end portion of the intermediate portion 10 and the other end portion are separated from each other. When the suction action and the repulsion action are repeated, the flow tube 3 is driven so as to vibrate in the direction of arrow Q in FIG.

  The vibration detection sensors 5 and 5 are sensors for detecting the vibration of the flow tube 3 and detecting the phase difference proportional to the Coriolis force acting on the flow tube 3 as described above. , Each comprising a coil and a magnet (not limited to this, it detects any of displacement, velocity, acceleration, such as acceleration sensor, optical means, capacitance type, distortion type (piezo type), etc. Any means).

  The vibration detection sensors 5 and 5 having such a configuration are respectively provided on the both sides of the drive device 4, specifically, on the upstream side and the downstream side of the drive device 4 using dedicated attachments at the same distance from the drive device 4. It is attached. 1, it is attached along the diameter (diameter in the first axis P direction) position of the intermediate portion 10 (other arrangement examples will be described later. The vibration detection sensors 5 and 5 are proportional to the Coriolis force. It is only necessary to be arranged at a position where the detected phase difference can be detected). Although not particularly illustrated, electric wires are drawn from the coils of the vibration detection sensors 5 and 5. The electric wire is connected to the converter (not shown).

  As described above, the connecting member 8 is a member for connecting the top portion 6 of the flow tube 3 and the rigid body 7 fixed to the housing 2, and the shape thereof is not particularly limited. It is formed in a thin strip shape, and both ends are fixed to the top 6 and the rigid body 7 by appropriate means. The connecting member 8 is formed so that the intermediate portion 10 of the flow tube 3 cannot move in the first axis P direction and can move in the second axis R direction orthogonal to the first axis P direction.

  The converter (not shown) includes a signal calculation processing unit (not shown) that performs calculation processing such as mass flow rate based on signals from the driving device 4, vibration detection sensors 5, 5 and a temperature sensor (not shown). And an excitation circuit section (not shown) for exciting the drive device 4.

  The signal calculation processing unit includes a detection signal from one vibration detection sensor 5 regarding the deformation of the flow tube 3, a detection signal from the other vibration detection sensor 5 regarding the deformation of the flow tube 3, and a temperature sensor. Wiring and connection are made so that detection signals relating to the temperature of the flow tube 3 are input. Such a signal calculation processing unit is configured to calculate mass flow rate and density based on each input detection signal. The signal calculation processing unit is configured to output the mass flow rate and density obtained by the calculation to a display (not shown).

  The excitation circuit unit includes a smoothing unit, a comparison unit, a target setting unit, a variable amplification unit, and a drive output unit. The smoothing unit is wired so as to extract a detection signal from one vibration detection sensor 5 (or the other vibration detection sensor 5). The smoothing unit has a function of rectifying and smoothing the input detection signal and outputting a DC voltage proportional to the amplitude. The comparison unit can compare the DC voltage from the smoothing unit with the target setting voltage output from the target setting unit, and can control the amplitude of the resonance vibration to the target setting voltage by controlling the gain of the variable amplification unit. It has such a function.

  In the above configuration, when the fluid to be measured is caused to flow through the flow tube 3 and the driving device 4 is driven so as to alternately and alternately repeat the suction and repulsion action, and the flow tube 3 is vibrated in the arrow Q direction, the vibration detection sensor 5 From the phase difference caused by the Coriolis force at point 5, the mass flow rate is calculated by the signal calculation processing unit. More specifically, when the driving device 4 is driven in the secondary mode as shown in FIG. 3A and the flow tube 3 is vibrated in the arrow Q direction, the points of the vibration detection sensors 5 and 5 (this point) Are PO7 and PO8, where the inflow side is PO8 and the outflow side is PO7), Coriolis force having the size of arrows PO7 and PO8 as shown in FIG. Here, D in FIG. 3B corresponds to the driving device 4. Further, P1 corresponds to the position of the connecting member 8. In such a state, when the phase difference is measured and calculated as shown in FIG. 3C, the mass flow rate is calculated.

  In this embodiment, the density is also calculated from the vibration frequency. Since the intermediate member 10 of the flow tube 3 is allowed to move in the second axis R direction by the connecting member 8, it acts in such a manner that it swings in the second axis R direction and amplifies the difference in phase.

  Next, with reference to FIGS. 4 to 6, a supplementary description will be given of the attachment positions of the vibration detection sensors 5 and 5. The flow tube 3 in FIGS. 4 to 6 is driven in the secondary mode as described above, and the Coriolis force at this time is as shown by the arrows in FIG. 3B. . In the examples of FIGS. 4 to 6, a vibration detection sensor is attached so that noise can be canceled comprehensively.

  In the example of FIG. 4, vibration detection sensors are attached at positions PO1, PO2, PO3, and PO4. PO1 and PO2 are located above the PO7 and PO8. PO3 and PO4 are located below PO7 and PO8. As can be seen from FIG. 4, the phase difference is measured at PO1 and PO2, the phase difference is measured at PO3 and PO4, and the phase difference is further measured.

  In the example of FIG. 5, vibration detection sensors are attached at positions PO1, PO2, PO5, and PO6. As can be seen from FIG. 5, the phase difference is measured by PO1 and PO2, the phase difference is measured by PO5 and PO6, and the phase difference is further measured.

  In the example of FIG. 6, vibration detection sensors are attached at positions PO1, PO2, PO3, and PO4. As can be seen from FIG. 6, this example differs from the example of FIG. 4 in that the phase difference is measured at PO1 and PO3, the phase difference is measured at PO2 and PO4, and the phase difference is further measured. It is configured as follows.

  As described above, since the Coriolis flowmeter 1 of the present invention connects the top portion 6 of the intermediate portion 10 of the flow tube 3 to the rigid body 7 using the connecting member 8, the movement direction of the intermediate portion 10 during vibration of the flow tube 3 is restricted. can do. Therefore, this makes it possible to stabilize the vibration frequency at each stage as compared with the prior art.

  In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

  That is, the shape of the flow tube 3 is not limited to the shape of FIG. For example, the flow tube may be formed in a shape as shown in FIGS. 7 (a) and 7 (b).

It is a figure which shows one Embodiment of the circle type single tube Coriolis flowmeter by this invention, (a) is a block diagram, (b) is a perspective view of the top part of a flow tube, and a connection member. It is a top view of a flow tube. (A) is a vibration waveform of a secondary mode, (b) is a waveform which shows Coriolis force, (c) is a circuit diagram which shows a measurement part. It is explanatory drawing which shows the other example of arrangement | positioning of a detection means. It is explanatory drawing which shows the further example of arrangement | positioning of a detection means. It is explanatory drawing which shows the further example of arrangement | positioning of a detection means. It is explanatory drawing which shows the other shape of a flow tube.

Explanation of symbols

1 Circle type single tube Coriolis flow meter (Coriolis flow meter)
2 Housing 3 Flow tube 4 Driving device (driving means)
5 Vibration detection sensor (detection means)
6 Top part 7 Rigid body 8 Connecting member 9 Support part 10 Intermediate part 11 First arm part 12 Second arm part 13 Crossing part P First axis R Second axis PO1 to PO8 Vibration sensor mounting position

Claims (2)

Rutotomoni comprises a single flow tube for flowing a fluid to be measured, a driving means for driving the flow tube, and a detecting means for detecting a phase difference proportional to a Coriolis force acting on the flow tube, the flow tube A single-tube Coriolis flowmeter comprising a connecting member for connecting a rigid body and a rigid body, wherein the flow tube is directed from a circle-shaped intermediate portion and a first support portion for the flow tube from one end of the intermediate portion. A first arm part extending in the shape of an arm and a second arm part extending from the other end of the intermediate part toward the second support part for the flow tube, and the drive said means of said intermediate portion other hand, the circle one type chew arranged at the intersections of the other end for driving the flow tube at the secondary or quaternary mode In the Coriolis flowmeter,
The connecting member is provided at the top of the circle-shaped intermediate portion located on the opposite side of the position of the driving means, and an axis connecting the first support portion and the second support portion is a first axis, If the axis perpendicular to one axis is the second axis, and the axial direction perpendicular to the first axis and the second axis is the arrangement direction of the driving means and the connecting member, the intermediate portion is configured to move the driving means to the second axis. When driven in the next or quaternary mode, a vibration in the circumferential direction occurs around the arrangement direction, and the connecting member cannot move the intermediate portion in the first axial direction and in the second axial direction. A circle-type single tube Coriolis flowmeter that is formed so as to be movable and functions as a member that regulates the moving direction of the intermediate portion in such a direction . In the circle type single tube Coriolis flow meter according to claim 1,
Circle type single tube Coriolis flowmeter characterized in that each length of the first arm part and the second arm part is equal to or longer than the length of the diameter in the first axial direction of the intermediate part. .

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