JP4033305B2 - Flow tube holding member - Google Patents

Description

  The present invention relates to a flow tube holding member attached to a fixed portion of a flow tube in a Coriolis flow meter.

  A Coriolis flowmeter supports one or both ends of a flow tube through which a fluid to be measured flows, and when vibration is applied in a direction perpendicular to the flow direction of the flow tube around the support point, This is a mass flow meter utilizing the fact that the Coriolis force acting on the flow tube to be added is called a flow tube) 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 provided with one flow tube (see, for example, Patent Document 1), one provided with two flow tubes in parallel (see, for example, Patent Document 2), or one There are known ones provided in a state in which a flow tube is looped (see, for example, Patent Document 3).

8 and 9, in the Coriolis flow meter of Patent Document 3 below in which one flow tube 101 is double-looped, the flow tube 101 is bent with the first bent tube portion 102 and the second bent tube portion 103. And a tube portion 104. The first bending tube portion 102 and the second bending tube portion 103 include a tube forming surface 105 (a surface formed along a virtual line in the drawing) formed by the first bending tube portion 102 and a second bending tube portion. The tube forming surfaces 106 formed by 103 are arranged in parallel with each other. The bending tube portion 104 is disposed and formed so as to exist between the first bending tube portion 102 and the second bending tube portion 103 in order to connect the first bending tube portion 102 and the second bending tube portion 103. Yes. The bent tube portion 104 is bent and formed as shown in the figure.
Japanese Examined Patent Publication No. 4-55250 Japanese Patent No. 2939242 Japanese Patent Publication No. 5-69453

  In the above prior art, since the bent tube portion 104 has a structure existing between the first bent tube portion 102 and the second bent tube portion 103, the first bent tube portion 102 and the second bent tube portion 103 are arranged. The flow tube 101 is formed so that the interval is relatively wide. As a result, the following problems arise from the arrangement of the drive means for driving the flow tube 101 and the detection means for detecting the phase difference and / or vibration frequency proportional to the Coriolis force acting on the flow tube 101. Dots have occurred.

  That is, since the coils and magnets constituting the driving means and the detection means need to be arranged close to each other, in the case of wide intervals such as the first bending tube portion 102 and the second bending tube portion 103, A dedicated holding member for holding the coil and the magnet must be formed large, and as a result, the weight of the portion where the driving means and the detecting means are present increases and the S / N ratio decreases. Dots have occurred.

  Thus, as a result of repeated studies on the above problems, the present inventor has come to find one countermeasure plan. In this measure, two tube forming surfaces formed by looping a single flow tube are arranged so that the tube drive side is substantially V-shaped with the tube drive side opened at a predetermined interval. This is a proposal to use a flow tube shaped so that the opposite side of the drive side is in a fixed state, and a good result was obtained that the above problems could be solved.

  By the way, the inventor of the present application has further found out the following things through further ingenuity. That is, the present inventors have found that the flow tube holding member, which is a rigid body, is welded to the fixed state portion to improve the vibration stability of the flow tube. The present inventor has also found that the vibration of the flow tube can be further stabilized by increasing the mass of the flow tube holding member welded to the fixed portion.

  However, if the flow tube holding member is welded to the fixed portion, for example, when the flow tube needs to be replaced, there is a problem that it is difficult or impossible to replace the flow tube.

  The present invention has been made in view of the above circumstances, and it is an object to provide a flow tube holding member capable of stabilizing the vibration of the flow tube in the Coriolis flowmeter and improving the maintainability of the flow tube. And

  The flow tube holding member of the present invention according to claim 1, which has been made to solve the above problems, is a split type in which a fixed state portion formed by fixing a tube assembly portion of a flow tube in a Coriolis flowmeter is detachably sandwiched. It is characterized by consisting of a rigid body.

  According to the present invention having such characteristics, when it is attached to the fixed portion of the flow tube, the function of stabilizing the vibration is exhibited. On the other hand, when the flow tube is disassembled and removed from the fixed state portion of the flow tube, for example, the flow tube can be maintained.

  A flow tube holding member according to a second aspect of the present invention is the flow tube holding member according to the first aspect, wherein a pair of block-like members in which grooves corresponding to the fixed portion are formed, and the pair of block-like members It is characterized by comprising a fastener for fixing each other, and a fixing portion for the housing in the Coriolis flowmeter is formed on one of the pair of block-like members.

  According to the present invention having such a feature, when the fixed state portion of the flow tube is sandwiched in each groove of the pair of block-shaped members, and the pair of block-shaped members are fixed to each other with a fastener from this state, the flow tube holding member Installation is complete. On the other hand, when the fastener is removed and the pair of block members are divided, the removal of the flow tube is completed. The flow tube holding member of the present invention has a structure that can be easily attached and detached.

  According to the first aspect of the present invention, there is an effect that the vibration of the flow tube in the Coriolis flow meter can be stabilized. In addition, the flow tube alone cannot be replaced, and the detector (sensor unit and main part of the flowmeter) must be replaced, and the inflexible structure is released. Thereby, there exists an effect that the maintainability of a flow tube can be improved. According to the second aspect of the present invention, there is an effect that a better form of the flow tube holding member can be provided. The present invention described in claims 1 and 2 is intended to provide an always stable measurement in which a flow tube can be exchanged in a fluid measurement that tends to be clogged intentionally, and to be expanded to a new field. There is an effect that can be.

Hereinafter, description will be given with reference to the drawings.
FIG. 1 is a view of a Coriolis flow meter showing an embodiment of a flow tube holding member of the present invention, (a) is a perspective view of a flow tube with a flow tube holding member attached, and (b) is a two tube formation. It is the figure which showed the surface typically. 2 is a perspective view of the flow tube, FIG. 3 is a view in the direction of A in FIG. 1, FIG. 4 is a perspective view (including a cross section) of a portion to be fixed, and FIG. 5 is an exploded perspective view of the flow tube holding member. FIG. 6A is a schematic diagram showing changes in vibration trajectories of two tube forming surfaces, and FIG. 6B is a schematic diagram showing changes in vibration trajectories of a comparative example.

  In FIG. 1, a Coriolis flow meter 1 includes a housing 2, a flow tube 3 housed in the housing 2, and a flow tube holding member 24 of the present invention attached to the flow tube 3. ing. Further, the Coriolis flow meter 1 has a sensor unit (not shown) having a driving device 4, a pair of vibration detection sensors 5, 5 and a temperature sensor (not shown), and a mass based on a signal from the sensor unit. A signal calculation processing unit (not shown) that performs calculation processing such as a flow rate and an excitation circuit unit (not shown) for exciting the drive device 4 are configured. The Coriolis flow meter 1 is characterized in that a split type flow tube holding member 24 is attached to the flow tube 3. Hereinafter, each component will be described with reference to FIGS. 1 to 5.

  The housing 2 has a structure that is strong against bending and twisting. 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.

  The flow tube 3 is formed by double looping a single flow tube for measurement. That is, the flow tube 3 is formed in a shape as shown in the figure having a first bending tube portion 6 and a second bending tube portion 7 continuous thereto. In addition to the first bending tube portion 6 and the second bending tube portion 7, the flow tube 3 includes an inflow tube 8 that is continuous with the first bending tube portion 6 and an outflow tube 9 that is continuous with the second bending tube portion 7. Have.

  In the flow tube 3, an inlet (not shown) and an outlet (not shown) are directly or indirectly fixed to the housing 2. Further, the flow tube 3 is in a fixed state (fixed state portion 17 described later), and is held by the flow tube holding member 24 of the present invention. The flow tube holding member 24 of the present invention is fixed to the housing 2.

  The first bending tube portion 6 and the second bending tube portion 7 of the flow tube 3 are each formed in an annular shape and arranged in a substantially V shape. Here, the arrangement of the first bending tube portion 6 and the second bending tube portion 7 will be described more specifically. First, a surface formed by the first bending tube portion 6 is a first tube forming surface 10, and a surface formed by the second bending tube portion 7 is a second tube forming surface 11. These two first and second tube forming surfaces 10 and 11 are arranged with an angle θ as shown in FIG. The fact that the two first and second tube forming surfaces 10 and 11 are arranged with an angle θ means that the two first and second tube forming surfaces 10 and 11 are arranged in a substantially V shape. become. Therefore, the 1st bending pipe part 6 and the 2nd bending pipe part 7 will be arrange | positioned in a substantially V shape (refer also FIG. 3 also about the substantially V-shaped arrangement | positioning).

  Note that the angle θ is an acute angle, and is arbitrarily determined depending on the shapes of the drive device 4 and the vibration detection sensors 5 and 5 (respective coils and magnets constituting the drive device 4 and the vibration detection sensors 5 and 5). It is assumed that the angle θ is set such that the two approach each other in a state where the smallest holding member is used.

  When the arrow line P in FIG. 1 is defined as the vertical direction and the arrow line Q is defined as the horizontal direction, the first bending tube portion 6 and the second bending tube portion 7 are both formed in a substantially rectangular shape extending in the horizontal direction. (It is assumed to be an example. An approximately rectangular shape extending in the vertical direction, an approximately elliptical shape, or an approximately circular shape is also possible). The first bending tube portion 6 and the second bending tube portion 7 have a common tube portion 12 that is common to the two. The common tube portion 12 is a portion corresponding to a continuous portion of the first bending tube portion 6 and the second bending tube portion 7 and is formed straight.

  In the first bent tube portion 6 and the second bent tube portion 7, reference numerals 13 and 13 indicate drive side tube portions. The drive side tube portions 13 and 13 are formed to be parallel to each other. The drive side tube portions 13 and 13 are formed straight. The center of the drive side tube portions 13, 13 is an attachment position for the drive device 4.

  The connecting portions with the tube portions 14 and 14 in the vertical direction at both ends of each drive side tube portion 13 are attachment positions with respect to the vibration detection sensors 5 and 5. The drive device 4 and the vibration detection sensors 5 and 5 are set to be attached at the same height from the position of the common tube portion 12.

  In FIG. 2, reference numerals 15 and 15 indicate the fixing side tube portion. The adhering side tube portions 15 and 15 are formed so as to be parallel to and in contact with the common tube portion 12. The adhering side tube portions 15 and 15 are arranged on both sides of the common tube portion 12. Such adhering side tube portions 15 and 15 are welded to the common tube portion 12. Reference numeral 16 indicates a welded portion. FIG. 4 shows a state in which the common tube portion 12 and the fixed-side tube portions 15 and 15 are welded together, and the three tubes are rigidly connected. A fixed state portion 17 is formed. FIG. 4 is an enlarged view of the fixed portion 17.

  In FIG. 2, the range H of the welded portion 16 is set to be shorter than the horizontal lengths of the first bent tube portion 6 and the second bent tube portion 7. It should be noted that the range H of the welded portion 16 is a range in which bending mode vibration (described later) occurs, and the stress accompanying this vibration is converted into the twist of the common tube portion 12 and the fixing side tube portions 15 and 15. If there is no particular limitation. The fixed portion 17 is formed in the range H by the welded portion 16. A flow tube holding member 24 of the present invention is attached to the fixed state portion 17 (described later).

  The inflow pipe 8 continuing to the first curved pipe section 6 has an inlet (not shown) of the flow tube 3 at one end. In addition, the inflow pipe 8 has a portion continuing to the fixed tube portion 15 at the other end. The inflow pipe 8 is formed such that a portion continuous with the adhering side tube portion 15 is bent. The other portions are formed straight.

  The outflow pipe 9 continuing to the second curved pipe section 7 has an outlet (not shown) of the flow tube 3 at one end. Further, the outflow pipe 9 has a portion at the other end continuous to the adhering side tube portion 15. The outflow pipe 9 is formed such that a portion continuous with the fixed-side tube portion 15 is bent (bends so as to straddle the lower side of the common tube portion 12 and the other fixed-side tube portion 15). The other portions are formed straight.

  The straight portions of the inflow pipe 8 and the outflow pipe 9 are arranged so as to be coaxial. Here, the axis connecting the inflow pipe 8 and the outflow pipe 9 is disposed so as to be substantially parallel to the axis of the fixed state portion 17 (for example, the central axis of the common tube portion 12) (an example). ).

  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.

  The flow tube holding member 24 of the present invention is a metal member (rigid body) having a sufficient mass, and is formed in a split type that allows the fixed state portion 17 to be freely attached and detached. That is, the flow tube holding member 24 includes, for example, two members including an upper block member 25 and a lower block member 26 as shown in the drawing, and an upper block member 25 and a lower block member 26. For example, a plurality of fasteners such as screws 27 to be fixed are provided. The material of the flow tube holding member 24 is made of stainless steel or the like.

  Three straight grooves 28 are formed on the opposing surfaces of the upper block member 25 and the lower block member 26. The groove 28 is formed in accordance with the shape of the fixed state portion 17. The fixed state portion 17 is sandwiched and held via the groove 28. The lower block member 26 is formed with a fixing portion 29 that is fixed to the housing 2 by appropriate means (this is a case where the lower block member 26 and the housing 2 are separated). The lower block member 26 may be integrally formed with the housing 2).

  The driving device 4 constituting the sensor unit is for causing the first bending tube portion 6 and the second bending tube portion 7 of the flow tube 3 to vibrate oppositely, and includes a coil 18 and a magnet 19. Has been. Such a drive device 4 is attached to the center of the drive side tube portions 13 and 13 of the flow tube 3 so as to be sandwiched between them. The driving device 4 is attached so that the coil 18 and the magnet 19 are close to each other with the minimum holding member (reference numeral omitted).

  The operation of the drive device 4 will be described. When an attracting action is generated in the drive device 4, the magnet 19 is inserted into the coil 18, and as a result, the drive side tube portions 13 and 13 of the flow tube 3 come close to each other. On the other hand, when the repulsion occurs, the drive side tube portions 13 and 13 are separated from each other. Since the flow tube 3 has the fixed state portion 17, the driving device 4 is configured to be driven alternately in the rotation direction around the fixed state portion 17.

  The vibration detection sensors 5 and 5 constituting the sensor unit are sensors for detecting the vibration of the flow tube 3 and detecting a phase difference proportional to the Coriolis force acting on the flow tube 3, respectively. It comprises a coil 20 and a magnet 21 (not limited to this, but detects any of displacement, velocity, acceleration, such as an 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 connected to the tube portions 14 and 14 in the vertical direction at both ends of each drive side tube portion 13 of the flow tube 3 (an example is assumed. Any other position can be used as long as it can detect a proportional phase difference. The vibration detection sensors 5 and 5 are attached so that the coil 20 and the magnet 21 approach each other in a state where a minimum holding member (reference numeral is omitted) is used.

  Although not particularly shown, a substrate or the like is provided inside the Coriolis flow meter 1. A wire harness drawn out of the housing 2 and, for example, electric wires from the driving device 4 and the vibration detection sensors 5 and 5 are connected to the substrate.

  The temperature sensor constituting a part of the sensor unit is a sensor for compensating the temperature of the Coriolis flow meter 1 and is attached to the flow tube 3 by an appropriate means. As a specific arrangement, for example, the inflow pipe 8 is suitable. An electric wire (not shown) drawn from the temperature sensor is connected to the substrate.

  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 the mass flow rate and the density based on each detection signal input from the sensor unit. 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 take out a detection signal from one vibration detection sensor 5 (or the other vibration detection sensor 5), rectifies and smoothes the input detection signal, and applies a DC voltage proportional to the amplitude thereof. It has a function that can output. 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, the fluid to be measured flows through the flow tube 3 to which the flow tube holding member 24 of the present invention is attached, and the driving device 4 is driven to drive the first bent tube portion 6 and the second bent tube portion 7 of the flow tube 3. Is countervibrated, the mass flow rate is calculated by the signal calculation processing unit based on the phase difference caused by the Coriolis force at the vibration detection sensors 5 and 5. The density is also calculated from the vibration frequency.

  In the flow tube 3, the first bent tube portion 6 and the second bent tube portion 7 are arranged in a substantially V shape and have a fixed state portion 17, so that the bending mode with the fixed state portion 17 as the center of the axis is provided. Vibration occurs. When the vibration of the bending mode is generated in the flow tube 3 by the drive of the driving means 4, the stress accompanying this vibration is converted into the twist in the axial direction. The vibrations of noise components that occur with each other are cancelled.

  According to the Coriolis flow meter 1 of the present invention, the first bent tube portion 6 and the second bent tube portion 7 of the flow tube 3 are arranged in a substantially V shape and have a fixed state portion 17 that is in a fixed state. Therefore, as shown in FIG. 6A, the size of the cross (described later) of the vibration trajectory 22 can be reduced and the change can be reduced. In addition, since the common tube portion 12 and the adhering side tube portions 15 and 15 are integrated, the bending resistance is controlled and a phase difference signal having a high S / N ratio can be obtained (reason: in the past). As shown in FIG. 6 (b), the first bent tube portion and the second bent tube portion of the flow tube 3 are arranged in a non-V shape, and the base end is fixed to a position away from the base tube. 6B, the two vibration surfaces vibrate independently of each other, so that the vibration trajectories 23 of the two vibration surfaces are inside the first bending tube portion and the second bending tube portion. In the conventional vibration state, the crossing and change of the vibration trajectories 23 and 23 are increased due to the behavior of the fluid, which affects the measurement result).

  As described above with reference to FIGS. 1 to 6, when the flow tube holding member 24 of the present invention is attached to the fixed state portion 17, the hook is also fixed due to the presence of the attached flow tube holding member 24. It seems that the mass of is increased. Therefore, there is an advantage that the vibration in the bending mode is stabilized. Moreover, since the flow tube holding member 24 of the present invention is detachable, it has an advantage that the Coriolis flowmeter 1 has good maintainability. The Coriolis flow meter 1 has an advantage that the S / N ratio is significantly improved as compared with the conventional one because the weight of the portion where the driving means 4 and the vibration detection sensors 5 and 5 are present is reduced.

  Next, another example of the flow tube 3 will be described with reference to FIG. FIG. 7 is a perspective view showing an example in which the axis connecting the inflow port and the outflow port and the axis of the portion in the fixed state are arranged in a substantially coincident state.

  In the above-described example (examples in FIGS. 1 to 5), the axis connecting the inflow pipe 8 and the outflow pipe 9 is arranged so as to be substantially parallel to the axis of the fixed state portion 17. It may be arranged in a state as shown in FIG. That is, it is also possible to use an arrangement in which the axis connecting the inflow pipe 8 and the outflow pipe 9 and the axis of the fixed state portion 17 are arranged in substantially the same state. As can be seen from FIG. 7, there is an advantage that the bent state of the portion continuing to the adhering side tube portion 15 becomes gentler than the above example.

  In FIG. 7, since there is no change of the adhering state portion 17, the flow tube holding member 24 of the present invention is naturally attached.

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

It is a figure of the Coriolis flowmeter which shows one embodiment of the flow tube holding member of this invention, (a) is a perspective view of the flow tube which attached the flow tube holding member, (b) is a model of two tube formation surfaces FIG. It is a perspective view of a flow tube. It is a figure of A viewing direction of FIG. It is a perspective view (a cross section is included) of the part used as the adhering state. It is a disassembled perspective view of a flow tube holding member. (A) is a schematic diagram which shows the change of the vibration locus of two tube formation surfaces, (b) is a schematic diagram which shows the change of the vibration locus of a comparative example. It is a perspective view which shows the example which has arrange | positioned the axis | shaft which connects an inflow port and an outflow port, and the axis | shaft of the part used as a fixation state in a substantially identical state. It is a perspective view which shows the flow tube of the Coriolis flowmeter of a prior art example. It is a top view of the flow tube of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coriolis flowmeter 2 Housing | casing 3 Flow tube 4 Drive apparatus 5 Vibration detection sensor 6 1st curved pipe part 7 2nd curved pipe part 8 Inflow pipe 9 Outflow pipe 10 1st tube formation surface 11 2nd tube formation surface 12 Common tube Part 13 Drive side tube part 14 Vertical tube part 15 Adhered side tube part 16 Welded part 17 Adhered state part 18, 20 Coil 19, 21 Magnet 22, 23 Vibration trajectory 24 Flow tube holding member 25 Upper side block-like member 26 Lower part Side block member 27 Screw (fastener)
28 Groove 29 Fixed part

Claims (2)

A flow tube holding member comprising a split-type rigid body that detachably holds a fixed state portion formed by fixing a tube assembly portion of a flow tube in a Coriolis flowmeter. In the flow tube holding member according to claim 1,
The Coriolis flow rate is provided in one of the pair of block-shaped members, and includes a pair of block-shaped members in which grooves corresponding to the fixed state portions are formed and a fastener for fixing the pair of block-shaped members to each other. A flow tube holding member characterized by forming a fixing portion for a housing in a meter.

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