JP3428563B2 - Coriolis mass flowmeter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Coriolis mass flowmeter, and more particularly to a coil and magnet arrangement of a Coriolis mass flowmeter of a type using two parallel flow tubes.

[0002]

2. Description of the Related Art When one end or both ends of a flow tube through which a fluid to be measured flows is supported and the flow tube is vibrated around the supporting point in a direction perpendicular to the flow direction of the flow tube, A mass flowmeter (Coriolis mass flowmeter) utilizing the fact that the Coriolis force acting on a flow tube to be added (referred to as a flow tube) is proportional to the mass flow rate is well known. The shape of the flow tube in this Coriolis mass flowmeter is roughly classified into a curved tube and a straight tube.

A Coriolis mass flowmeter of a type that uses one flow tube, whether it is a curved tube type or a straight tube type,
When vibrating in a direction perpendicular to the central portion of the flow tube whose both ends are supported, the flow tube displacement difference due to the Coriolis force between the support portion and the central portion of the flow tube,
That is, the mass flow rate is detected as the phase difference signal. Although such a type of Coriolis mass flowmeter has a simple, compact and robust structure, it has a problem that it is easily affected by external vibration and temperature.

In order to solve such a problem, it is known that two flow tubes are arranged in parallel. The measuring fluid is equally split into two flow tubes on the inlet side and joins on the outlet side of the flow tube. Two
Even if the type of fluid changes or the temperature fluctuates by flowing the measuring fluid evenly through the flow tube of the book,
It is known that the natural frequencies of the two flow tubes can always be made equal, which enables efficient and stable driving, and a Coriolis mass flowmeter that is less affected by external vibration and temperature. There is.

A drive device for driving such a flow tube composed of two parallel tubes in the central portion is usually composed of a coil and a magnet. 2 coils for drive
In one of the flow tubes of the book, and the magnet,
It is attached to the other flow tube, and these two flow tubes are resonantly driven in opposite phases. Further, a pair of vibration detection sensors, each composed of a coil and a magnet, are installed at symmetrical positions on the left and right sides with respect to the mounting position of the drive device, and detect a phase difference proportional to the Coriolis force. The coil and magnet of this sensor are also separately fitted with a coil on one flow tube and a magnet on the other flow tube.

Wiring is required only for the coil for the driving device and the pair of vibration detecting sensors, and therefore the wiring can be attached to the surface of only the flow tube to which the coil is attached. For this reason, the conventional Coriolis mass flowmeter of the type having two parallel flow tubes has a poor balance between the two flow tubes, which adversely affects the performance of the Coriolis mass flowmeter. This is especially true with small diameter flow tubes,
There has been a big problem in the case of a small Coriolis mass flowmeter in which a coil and a magnet of a drive device and a pair of vibration detection sensors are mounted on the flow tube. The drive device and the detection sensor added to the small-diameter flow tube are naturally limited.

[0007]

Therefore, in order to solve such a problem, the present invention arranges only the magnets of the driving device and the pair of sensors in the two flow tubes in a symmetrical structure. The purpose of this is to maintain the balance between the two flow tubes and reduce the adverse effect on the performance of the Coriolis mass flowmeter.

[0008]

A Coriolis mass flowmeter according to the present invention comprises two flow tubes 1 and 2 arranged in parallel, and one flow tube located at the center of the flow tubes 1 and 2 and the other flow tube. A drive device 15 for resonantly driving the tube in mutually opposite phases, and a pair of vibration detection devices installed at symmetrical positions on the left and right sides with respect to the mounting position of the drive device 15 to detect a phase difference proportional to the Coriolis force. Sensor 1
6 and 17, the drive unit 15 and the pair of vibration detection sensors 16 and 17 are composed of a coil and a magnet, respectively. A coil bracket 9 having a natural frequency substantially equal to the natural frequency of each flow tube is provided in the center between the two parallel flow tubes 1, 2, and the coil bracket 9 includes the drive device 15 and a pair of vibrations. Each of the detection sensors 16 and 17 is provided with a coil, and a magnet corresponding to the coil is attached to the two flow tubes 1 and 2.
It is characterized by mounting so as to face each of the.

The two parallel flow tubes 1 and 2 of the Coriolis mass flowmeter of the present invention are branched and merged in the manifolds 24 and 25 which are connected on the inflow side and the outflow side, respectively, and the inflow side and the outflow side are combined. The side manifolds 24 and 25 smoothly draw a circular arc from the inflow port and are turned upward in a predetermined angle direction to reach the connection ports with the two flow tubes 1 and 2, and the two connected flow tubes. 1, 2 and the manifolds 24, 25 form a smooth arcuate shape as a whole.

The two Coriolis mass flowmeters of the present invention are provided with two flow tubes 1 and 2 in the vicinity of both ends thereof, respectively.
The two coil tubes 9 are fixed to each other by two substrates 20 and 21 spaced apart from each other so that the two flow tubes 1 and 2 are maintained in parallel. Are also fixed together, and the coil bracket 9 is supported only by the fixation by the two substrates 20 and 21.

Further, the Coriolis mass flowmeter of the present invention is provided with a mounting tube 10 with its tip facing the driving device 15, and the driving device 15 and a pair of detection sensors 16 are provided from the outside of the flowmeter using the mounting tube 10. , 17 can be electrically wired, and the coil bracket 9 can be attached to and supported by the attachment cylinder 10.

Further, in the present invention, two parallel flow tubes are composed of one continuous tube curved in a gate shape, and each end of each of the two parallel flow tubes is outside. The present invention can be applied to a Coriolis mass flowmeter configured to be fixed on both the upper side and the lower side of a fixing member 37 that is fixed to the housing 30 and has a substantially rectangular cross section. In such a Coriolis mass flowmeter, the end portion of the coil bracket 9 located in the center between the two parallel flow tubes is also fixed on both the upper side and the lower side of the fixing member 37, and the two parallel tubes are connected. The flow tube and coil bracket are secured together by the substrate 22 near the ends on both sides.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is equally applicable to a Coriolis mass flowmeter using two parallel flow tubes, but a coriolis mass flowmeter of a bow tube type using two parallel flow tubes is first described. The description will be given below by taking the first example. FIG. 1 is a vertical cross-sectional view showing a Coriolis mass flowmeter provided with the coil bracket of the first example of the present invention, and the flow tube on the front side is removed and shown on the right side from the center of the figure. FIG. 2 shows a cross-sectional view cut at the center of FIG. The exemplary Coriolis mass flowmeter is
In use, it can be mounted horizontally or vertically, and when it is mounted horizontally, the curved convex part at the center of the flow tube should be mounted upward as shown in the figure, or the reverse. It is possible to mount it on the bottom. However, in the case of gas measurement, it is desirable to make the curved convex part up as shown in the figure so that the liquid does not stay in the curved convex part in the center of the flow tube. It is desirable that the curved convex portion is attached downward so that air bubbles do not stay.

The two flow tubes 1 and 2 of the illustrated Coriolis mass flowmeter are arranged in parallel with each other, and the flow tubes having the same shape curved in an arc shape. Both ends of each are connected to the inlet side manifold 24 and the outlet side manifold 25 by welding or the like. The illustrated Coriolis mass flowmeter is configured symmetrically, but the following description will be made assuming that the measurement fluid flows in from the left side of FIG. 1 and flows out to the right side. The measurement fluid flows in from an external flow pipe connected via a flange 18, and is equally branched into two flow tubes 1 and 2 at an inlet side manifold 24 from one inflow port. On the outlet side of the flow tubes 1 and 2, the outlet side manifold 2 is made symmetrical with the inflow side.
They join together at 5 and flow out to the external flow pipe connected via the flange 19.

On the inlet side, the manifold 24 is
An arc is drawn from the inflow port and smoothly turned to a predetermined upper angle direction to reach the connection port with the flow tubes 1 and 2. In this way, by setting the tube connection port of the manifold at the tube rising angle, the flow tube itself is simply curved in one direction, and the connected flow tubes 1 and 2 and the manifolds 24 and 25 as a whole are Construct a smooth bow shape.

As described above, the flow tubes 1 and 2 themselves, which play an important function for vibration measurement, only have a structure in which they are simply curved in one direction, and the flow tubes have two flow paths. The manifolds 24 and 25 correspond to complicated flow path changes from the direction to the external piping direction. The flow tubes 1 and 2 can be fixed to the manifold by welding or the like, and the heat stress is absorbed by forming the flow tube into an arc shape, and the structure has a strong structure against piping stress.

Two substrates, an upper substrate 20 and a lower substrate 21, are provided in the vicinity of both ends of the flow tubes 1 and 2, respectively, in order to form nodes that vibrate when driven. These two substrates are fixed to each other so that the flow tubes 1 and 2 are maintained in parallel, and at the same time, as will be described later in detail, the two flow tubes 1 and 2 are joined together.
The coil bracket 9 located between the two is also fixed together. The flow tubes 1 and 2 vibrate with the fixing point of the upper substrate 20 serving as the first fulcrum of vibration and the coupling end of the lower substrate 21 serving as the second fulcrum.

The drive device 15 is provided at the center of the inflow side and the outflow side of the arcuate flow tube, and a pair of detection sensors 16 and 17 are provided on the left and right sides of the drive device 15, respectively, and the drive device. 15 and the pair of detection sensors 16 and 17 are each made up of a coil and a magnet, which is no different from the conventionally known conventional technique. However, the Coriolis mass flowmeter of the present invention is designed so that the two flow tubes 1 and 2 are symmetrical to each other.
Only the respective magnets of the drive device 15 and the pair of detection sensors 16 and 17 are attached to the flow tubes 1 and 2. Drive device 15 and a pair of detection sensors 16,
Each of the 17 coils is attached to a coil bracket 9 located between the flow tubes 1 and 2.

FIG. 3 is a view showing only the coil bracket for mounting the coils of the driving device and the detection sensor, and the view seen from the direction of arrow A is shown on the upper left side thereof. FIG. 5 shows a cross-sectional view cut by the drive unit, and FIG. 6 shows a cross-sectional view cut by the detection sensor unit.

The coil bracket 9 is located between the two flow tubes 1 and 2, and the coils of the driving device 15 and the pair of sensors 16 and 17 can be attached to the coil bracket 9. The natural frequency of the coil bracket 9 will be described later. Any shape such as a tubular shape, a rod shape, or a plate shape can be used as long as it can be matched with that of the flow tube. As shown in FIG. 3, the exemplified coil bracket is obtained by brazing linear pipes or rod-shaped members located on both sides integrally with a curved plate-shaped member located in the center, and thus, as a whole, a flow tube is provided. The shape is almost the same as the bow shape. By configuring in this way, not only does its natural frequency match that of the flow tube,
It is possible to reduce the change of the moment of inertia of area in the tube axis direction and to deform it in the same manner as the flow tube, and at the same time, it is possible to easily process, assemble, and attach the coil bracket.

The coil bracket to which the electrically wired coils are attached is mechanically coupled to the flow tubes 1 and 2 by the upper substrate 20 and the lower substrate 21, respectively, only on the inflow side and the outflow side. It The electrical wiring to each coil is, as shown in FIG. 1, from the outside of the flow meter to the inside of the flow meter through the inside of the mounting tube 10, to the coil bracket 9 through the flexible printed boards 12 and 13, and from there. Guided by each coil. The flexible printed board itself is a well-known one, and here, a board having a predetermined width in which a copper foil for wiring is sandwiched between polyimide films can be used. This flexible printed board 1
As shown in FIG. 2, 2 and 13 are configured to have the same rigidity and shape so as to form a pair on each side of the two flow tubes so as to minimize the influence of mass and the like. ing. Wiring is provided to a pair of detection devices located on both left and right sides of the drive device through a Teflon (registered trademark) wire (copper wire or copper foil covered with Teflon) fitted on the surface of the coil bracket 9. It can be carried out.

The mounting cylinder 10 is located at the center of the left and right, and the main body 26 is penetrated through and supported by the drive device 15 so that the front end surface thereof faces the drive device 15. By equipping the main body 26 with the mounting cylinder 10 for such electrical wiring, and by tightly connecting the manifold portions on both sides, and by connecting the case 27 to the main body 26, the inside of the flowmeter can be It becomes possible to configure in a sealed state.

FIG. 5 shows a sectional view taken along the line of the drive unit of FIG. As shown in FIG. 2, the coil bracket 9 is formed in a plate shape in the central portion between the inflow side and the outflow side, but the drive device has a plate-shaped coil bracket as shown in FIG. A hole is drilled in 9, and the coil bobbin 33 and the coil 3 are attached thereto. The illustrated coil bobbin 33 is at right angles to the tube axis direction and at the upper and lower sides in the figure perpendicular to the line connecting the two flow tubes 1 and 2,
It is attached to the coil bracket 9. Coil bobbin 3
3 is further provided with a hole in the center, in which the drive device magnets 5 and 6 attached to the two flow tubes 1 and 2 face each other and are positioned at a predetermined interval. There is. The drive device magnets 5 and 6 are attached via the magnet brackets 34 and 35 as shown in the drawing. Thus, in the flow tubes 1 and 2,
Only the magnets (and magnet brackets) are symmetrically attached and are configured to be driven in opposite phases. Excitation of the drive coil can be accomplished either by switching it on and off, or by switching it in the opposite direction.

FIG. 6 shows a sectional view taken along the detection sensor portion of FIG. The mounting of the coil 4 of the detection sensor to the coil bracket 9 and the mounting of the magnets 7 and 8 to the flow tubes 1 and 2 are basically the same as in the case of the drive device described with reference to FIG. , Detailed description is omitted.

In operation, the driving device 15 resonantly drives the two flow tubes 1 and 2 in the opposite phase at the center of the two parallel flow tubes 1 and 2. As a result, the drive device magnets 5 and 6 (see FIG. 5) are arranged so that the magnetic poles of opposite polarities face each other. The pair of vibration detection sensors 16 and 17 are installed at left and right symmetrical positions with respect to the mounting position of the drive device 15, and detect a phase difference proportional to the Coriolis force. The polarities of the magnets of the detection sensor can be either magnetic poles having the same polarity or magnetic poles having different polarities. However, if the flow tube has a small diameter and does not have rigidity enough to withstand the attraction force of magnetic poles of different polarities, and if there is a risk of close contact, it is desirable to use the same polarity. In addition,
The illustrated drive device 15 and the pair of vibration detection sensors 16,
All of the magnets 17 are arranged between the tube axes of the flow tubes 1 and 2, so that a driving force acts on the line connecting the central axes of both flow tubes, and is based on this driving force. Since the Coriolis force can be detected, the moment of inertia due to the vibration inertial force does not occur.

Since the driving device 15 resonantly drives the two flow tubes 1 and 2 in opposite phases to each other, the driving device coil positioned between the two parallel flow tubes 1 and 2 and the coil to which the driving device coil is attached. The bracket itself basically does not vibrate. When disturbance vibration is generated from outside the flow meter, the flow tube vibrates undesirably, but the coil bracket also needs to be configured to vibrate the same as the flow tube. When an undesired relative position change occurs between the drive magnet attached to the flow tube and the drive coil attached to the coil bracket, the two flow tubes 1 and 2 are symmetrically driven in opposite phases. If there is an undesired change in relative position between the detection sensor magnet attached to the flow tube and the detection sensor coil attached to the coil bracket, disturbance vibration may cause a noise signal. May be detected as

From the nature of disturbance vibration,
The natural frequency of the coil bracket is
It is necessary to at least substantially match the natural frequency of the in-phase first order, and regarding the twist mode (vibration that twists in opposite directions on the left and right detection sensor sides),
It is desirable to match them as much as possible. Such adjustment of the natural frequency of the coil bracket can be performed by appropriately selecting the material, rigidity, shape and the like of the coil bracket.

Further, the above-mentioned arrangement of the coil and the magnet of the driving device and the detection sensor of the present invention is configured to compensate for the disturbance vibration. With reference to FIG. 7, the effect compensation for the disturbance of the drive device will be described. In the drive,
The flow tube is vibratingly driven by switching S-N by the current flowing through the coil to repel and attract the magnet. Originally, as shown in FIG. 7 (b), an average vibration surface exists in the center of the two magnets (interval δ) that are attached to face each of the two flow tubes, and the magnets are attached to the coil bracket. The coil is configured such that its center is located on the average vibration plane. If the coil is at the center of the magnet, it will not vibrate,
The energy may be the minimum, but if the coil deviates from the center, as shown in FIG. 7A, the coil vibrates, and energy for that is required. Therefore, when the coil is provided between the two magnets, it has a self-centering function of being automatically located at the center thereof. Therefore, even if the coil is displaced from the center due to a disturbance or the like, the coil automatically comes to the center position, and the influence of the disturbance or the like is eliminated.

Further, in the present invention, as shown in FIG. 7 (c), since the magnetic flux is substantially uniform between the two magnets by using the two magnets, in this uniform region, As described above, even if a slight deviation occurs, the magnetic flux densities passing through the coil are complemented by the two magnets and do not change much.

Next, with reference to FIG. 8, the effect compensation for the disturbance of the detection sensor will be described. The magnetic flux that contributes to the generation of the current flowing through the coil when the magnet vibrates is the radial component of the magnetic flux that intersects the coil. If there is only one magnet, the magnetic flux will change greatly depending on the distance from the magnetic pole. On the other hand, as shown in the figure, when the two magnets are opposed to each other with an appropriate gap, the relative position of the coil with respect to the magnets becomes (a) (b) (c) as shown in the figure due to disturbance, for example. Even if it changes as described above, since the two magnets complement each other, the radial component of the magnetic flux intersecting the coil does not change much.

FIG. 9 is a diagram showing the action of fixing two flow tubes and a coil bracket by using two substrates, an upper substrate and a lower substrate, by modeling the two flow tubes and the coil bracket. Is. The figure shows two states in which the flow tube and the coil bracket are swung to the right and left by the disturbance vibration. According to the present invention, the two flow tubes can be made to have the completely same symmetrical structure, and therefore, they can be vibrated in the same manner with respect to the disturbance vibration. On the other hand, although it is desirable to match the natural frequency of the coil bracket with that of the flow tube, even if it is not possible to match them completely at all, use two substrates, an upper substrate and a lower substrate. It becomes possible to make the same vibration by fixing by fixing.

FIG. 4 is a view showing a coil bracket of the second example of the present invention. The configuration other than the coil bracket may be the same as that described above. The coil brackets are fixed to both side surfaces of the mounting cylinder 10 via a pair of coil bracket mounting plates 23, 23, respectively. The coil bracket mounting plates 23, 23 can be plate-shaped and have a notch formed on the tip side, and the plate-shaped coil bracket 9 can be sandwiched in the notch and fixed by brazing or the like. Even with such a mounting configuration, it is possible to vibrate the flow tube and the coil bracket in the same manner against a disturbance by appropriately selecting the material, rigidity and shape.

FIG. 10 is a vertical sectional view showing a Coriolis mass flowmeter provided with the coil bracket of the third example of the present invention, and FIG. 11 is a transverse sectional view cut in a direction perpendicular to FIG. ing. This example shows a case where the present invention is applied to a Coriolis mass flowmeter having two parallel curved tube type flow tubes configured by bending one tube.

The flow tubes 1 and 2 of the illustrated Coriolis mass flowmeter are curved tubes of the same shape that are curved in a portal shape, and are constituted by one continuous conduit. The flow tube is a flow tube portion that is resonantly driven to generate a Coriolis force, and is represented as a flow tube 1 and a flow tube 2, and a connecting portion that connects these two flow tubes to each other, The whole including the inlet portion and the outlet portion connected to the external pipe is configured by one conduit. This Coriolis mass flowmeter is bilaterally symmetric and can flow in and out from either side.
It is assumed that the gas flows in from the left side of FIG. 10 and flows out from the right side.

The fluid to be measured passes through the conduit inlet portion from the external inlet pipe, enters the lower left side of the flow tube 2 (hidden behind the flow tube 1 in FIG. 10), and further from the lower right side of FIG. The flow tube 1 enters the flow tube 1 from the left side of FIG. 10 through the connection portion, and flows out from the lower right side of the flow tube 1 through the conduit outlet section to the external outlet pipe. In the vicinity of both ends of the flow tubes 1 and 2,
A substrate 22 is provided and this includes a flow tube 1,
The two are stuck together so that they are maintained in parallel.

The respective ends of the flow tubes 1 and 2 are connected to a fixing member 37 which is hollow and has a substantially rectangular cross section. The respective end portions of the respective flow tubes are fixed to both the upper side and the lower side of the rectangle of the fixing member 37. As a result, each end of one flow tube is supported at two points on the two sides of the hollow rectangle, and another two sides constituting the side surface of the hollow rectangular fixing member 37 are as shown in FIG. Is fixed to the outer casing 30.

The outer casing 30 has a shell structure having a concave portion, and the outer casing 30 is provided with an outer casing inlet portion and an outlet portion, through which the inlet and outlet conduit portions are respectively passed, It is fixed by welding. Furthermore, this outer casing 30
The pressure-resistant case 27 is integrally and tightly joined to the housing by suitable means such as welding.

The drive device 15 and the pair of detection sensors 16,
The wiring to the coil to 17 is provided from the outside of this Coriolis mass flowmeter to the wiring introducing portion 38 attached to the outer casing 30.
Along the support 11 attached to the fixing member 37, and is connected from the tip end thereof via the flexible printed board 12.

Also in the Coriolis mass flowmeter of the type having the flow tube curved in such a gate shape, the drive device 15 and the pair of detection sensors 16, 16 using the coil bracket 9 as described above with reference to FIG. 17 can be attached. Similar to FIG. 1, only the drive device 15 and the respective magnets of the pair of detection sensors 16 and 17 are attached to the flow tubes 1 and 2. Drive device 1
The coils of 5 and the pair of detection sensors 16 and 17 are attached to a coil bracket 9 located between the flow tubes 1 and 2. As shown in FIG. 11, the coil bracket 9 to which each coil having electrical wiring is attached is provided only on the inflow side and the outflow side, as shown in FIG.
Then, the upper side and the lower side of the rectangle of the fixing member 37 are fixed by brazing or the like.

[0040]

The Coriolis mass flowmeter of the present invention has a parallel 2
In the center between the two flow tubes, a coil bracket having a natural frequency substantially equal to the natural frequency of each flow tube is provided, and the coil bracket is provided with each coil of the drive device and the pair of vibration detection sensors. At the same time, the flow tube is correspondingly fixed only with a total of three magnets for the driving device and a pair of detection sensors, so it is easy to obtain a symmetrical structure that is important in forming tuning fork vibration. This makes it possible to maintain the balance between the two flow tubes and reduce the adverse effect on the performance of the Coriolis mass flowmeter.

Further, since the flexible printed board, the wiring, and the fixing tape for wiring are not attached to the flow tube, good results can be obtained from the viewpoint of attenuation characteristics.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a Coriolis mass flowmeter including a coil bracket according to a first example of the present invention.

FIG. 2 is a cross-sectional view taken along the center of FIG.

FIG. 3 is a diagram showing only a coil bracket for mounting respective coils of a driving device and a detection sensor.

FIG. 4 is a diagram showing a coil bracket of a second example of the present invention.

5 is a cross-sectional view taken along the drive unit of FIG.

FIG. 6 is a cross-sectional view cut by the detection sensor unit of FIG.

FIG. 7 is a diagram for explaining influence compensation for a disturbance of the driving device.

FIG. 8 is a diagram for explaining influence compensation for a disturbance of a detection sensor.

FIG. 9 is a plan view showing a case where two substrates, an upper substrate and a lower substrate, are used,
It is a figure which shows the effect | action of fixing two flow tubes and a coil bracket by modeling two flow tubes and a coil bracket.

FIG. 10 is a vertical cross-sectional view showing a Coriolis mass flowmeter including a coil bracket according to a third example of the present invention.

11 shows a cross-sectional view taken in a direction perpendicular to FIG.

[Explanation of symbols] 1 flow tube 2 flow tubes 3 drive coil 4 Detection sensor coil 5 Drive magnet 6 Drive magnet 7 Detection sensor magnet 8 Detection sensor magnet 9 coil bracket 10 Mounting tube 12 Flexible printed board 13 Flexible printed board 15 Drive 16 detection sensor 17 Detection sensor 18 flange 19 flange 20 upper substrate 21 Lower substrate 22 Substrate 23 Coil bracket mounting plate 24 Manifold 25 Manifold 26 body 27 cases 30 outer casing 33 coil bobbin 34 Magnet bracket 35 magnet bracket 37 fixing member 38 Wiring introduction section

Continuation of the front page (56) Reference JP-A-5-196488 (JP, A) JP-A-2000-46614 (JP, A) JP-A-11-337383 (JP, A) JP-A-11-351939 (JP, A) Japanese Patent Laid-Open No. 2000-65618 (JP, A) Special Table 2-500537 (JP, A) Special Table 2-501006 (JP, A) US Patent 4756198 (US, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G01F 1/84

Claims (5)

(57) [Claims] 1. Two parallel flow tubes, and a drive device located at the center of the inflow side and the outflow side of the flow tubes to resonately drive one flow tube with respect to the other flow tube in mutually opposite phases. And a pair of vibration detection sensors installed at symmetrical positions on the inflow side and the outflow side with respect to the mounting position of the drive device and detecting a phase difference proportional to the Coriolis force. In a Coriolis mass flowmeter, each of which has a detection sensor composed of a coil and a magnet, in the center between the two parallel flow tubes, a natural vibration at least approximately equal to the primary natural frequency of at least the same phase of each flow tube. A coil bracket having a number, and each coil of the drive device and the pair of vibration detection sensors is provided in the coil bracket. With obtaining a magnet corresponding thereto, mounted symmetrically so as to face each of the two flow tubes, Coriolis mass flowmeter, characterized in that. 2. The two parallel flow tubes branch and merge in a manifold connected at an inflow side and an outflow side, respectively, and the inflow side and the outflow side manifold have arcs from their inflow ports and outflow ports. 2. The drawing smoothly turns to a predetermined upper angle direction to reach a connection port for connecting two flow tubes, and the two connected flow tubes and the manifold form a smooth arc shape as a whole. Coriolis mass flowmeter described in. 3. The two flow tubes are fixed to each other in the vicinity of both ends thereof by two substrates spaced apart from each other so that the two flow tubes are maintained in parallel. The Coriolis mass flowmeter according to claim 2, wherein the coil brackets located between the flow tubes are also fixed together, and the coil brackets are supported only by fixing by these substrates. 4. A mounting tube is provided with its tip end facing the driving device, and the mounting tube is used to electrically connect the driving device and the pair of detection sensors from outside the flow meter to the mounting tube. The Coriolis mass flowmeter according to claim 2, wherein the coil bracket is attached and supported. 5. The two parallel flow tubes are composed of one continuous tube curved in a gate shape, and each end of the two parallel flow tubes is fixed to an outer casing. The cross-section of the coil bracket is fixed to both the upper side and the lower side of the fixing member which is hollow and has a substantially rectangular shape, and the end portion of the coil bracket located in the center between the two parallel flow tubes is also fixed. The Coriolis mass flowmeter according to claim 1, wherein the two parallel flow tubes and the coil bracket are fixed on both the upper side and the lower side of the member, and are fixed to each other by the substrate near the ends on both sides.