JP2966337B2 - Coriolis flow meter - 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 flowmeter, and more particularly, to an external cylinder of a Coriolis flowmeter having a straight pipe-shaped flow tube, in which drive means and detection means are electrically connected to each other. The present invention relates to a conductor for leading to a terminal.

[0002]

2. Description of the Related Art As is well known, a Coriolis flowmeter supports a flow tube through which a fluid having a mass flow rate m flows, and applies alternating vibration at an angular velocity ω around a supporting point. It utilizes the fact that the Coriolis force F proportional to the vector product of the angular velocity ω acts, and is based on the principle of measuring the Coriolis force and obtaining the mass flow rate. That is, the flow tube is deformed by the Coriolis force F, and a phase difference is generated between the support positions in proportion to the Coriolis force. The mass difference m can be directly obtained by detecting the phase difference. Further, by selecting the angular velocity ω as the natural frequency ω ₀ around the support point, the natural frequency ω ₀
Can be used to measure the fluid density ρ. As described above, the flow tube generates a Coriolis force F and further forms a main part of the Coriolis flowmeter for obtaining the density ρ, and its shape is particularly important.

[0003] The shape of the flow tube is roughly classified into a curved shape and a straight tube shape, and the support position has a large phase difference displacement due to the Coriolis force and a curved shape capable of detecting a Coriolis force having an excellent SN ratio. Is often used.
On the other hand, while the curved shape becomes large, the straight tube shape has an advantage that a simple and small Coriolis flowmeter can be obtained. However, the straight tube-shaped flow tube has the disadvantage that the amount of deformation due to Coriolis force is small and the SN ratio is low. Therefore, in a Coriolis flowmeter having a straight tube shape, a resonance driving means capable of driving with a small electric power by driving the straight tube flow tube at a natural frequency around the support point is employed.

In a straight tube type Coriolis flow meter, a driving unit and a Coriolis force detecting unit detect driving means similar to that of a curved tube type Coriolis flow meter, and detect Coriolis force as a phase difference signal of a flow tube. In addition, a temperature sensor or the like for detecting the temperature of the flow tube is attached in order to correct the influence of the temperature change of the fluid. The drive unit is, for example, an electromagnetic drive system including an electromagnetic coil and a solenoid, and the detection unit is also often an electromagnetic detection system including a permanent magnet that forms a magnetic path facing the detection coil. Thus, a phase difference proportional to the Coriolis force is detected as a sinusoidal voltage signal generated by the relative movement of the detection coil and the magnet.

The electric connection with the driving means, the detecting means and the temperature sensor is made by a plurality of electric cables fixed along one of a coaxial tube and a parallel tube having an electric connection portion. It is connected to the terminal of a terminal box provided on the outer cylinder of the meter, and is led out to a mass flow rate calculation unit provided inside or outside the terminal box. Electric wire cable
A flexible wire coated with a resin such as Teflon is used as the core wire with a plurality of thin copper wires as the core wire, and is fixed with an adhesive or the like on a thin cloth material wound around the outer circumference of the tube to be attached, and the flow tube is used. The power cable is prevented from peeling or separating from the flow tube due to the vibration.

[0006] Coriolis flow meters are mass flow meters that measure the mass flow rate of various types of fluids, and therefore are often mounted in explosion-proof danger locations. In such a case, the Coriolis flowmeter must have an explosion-proof structure in accordance with the explosion-proof standard. For example, the outer cylinder of the Coriolis flow meter is filled with an inert gas such as argon gas, and the electric wire cable connecting between the drive unit, the detection unit and the external terminal of the explosion-proof structure has a seal structure at an intermediate position. And is hermetically derived.

FIG. 5 is a diagram for explaining a method of connecting electric wires and cables in a conventional explosion-proof structure. FIG. 5 (A) shows an internal connection system, and FIG. 5 (B) shows an external connection system.
20 is a flow meter outer cylinder side, 21 is a terminal box side, 22 is a molding material, 23, 24, 26 and 27 are electric wires and cables, 25 is an electric wire, and 28, 29 and 30 are connection parts.

In FIG. 5, the connection of the electric cable is performed by connecting pipes (not shown) for hermetically connecting the outer cylinder and the terminal box (not shown) between the flow meter outer cylinder side 20 and the terminal box side 21. ), For example, a molding material 22 such as resin
Done through. In the internal connection system shown in FIG. 5 (A), the power cables 23 and 24 are configured such that a predetermined length of the core wires 23a and 24a is led out between the coating and the plurality of core wires 23a and 24a to form a connection portion 28. In this method, the outer cylinder side 20 and the terminal side 21 are prevented from communicating with each other through a space between the plurality of core wires 23a and 24a, and are fixed with a mold material to maintain airtightness. In the external connection method shown in FIG. 5B, a plurality of single wires 25 are air-tightly fixed in a molding material 22 in advance, and each of the wires 25 has a flow meter outer cylinder side 20 and a terminal box side 2.
1 and the core wires 26a, 27 of the electric cables 26, 27, respectively.
This is a connection method of connecting part a by soldering or the like at connection portions 29 and 30.

[0009]

The driving means and the detecting means of the Coriolis flowmeter are attached to a vibrating member such as a flow tube with a predetermined mass. Therefore, the electric cables connected thereto also vibrate. However, although the electric cable is covered with a flexible resin as described above,
Resin is a plastic material, has high internal friction, and acts as a kind of damper against vibration. The core wire also consists of a plurality of extra fine wires, and even if it is an elastic body itself, relative displacement due to vibration occurs between adjacent wires, thereby causing frictional resistance. This is a factor that lowers the resonance characteristics. Further, the cloth material and the adhesive for fixing the electric cable to the flow tube or the like also provide a damper effect similarly to the electric cable, and have a characteristic contrary to an attempt to keep the driving energy as small as possible and to increase the SN ratio. .

In particular, in the case of an explosion-proof structure, as shown in FIG.
Because there are many places where wires are connected and the connection is complicated,
For this reason, there has been a problem that many man-hours are required and the cost is high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and reduces vibration attenuation due to wiring of a vibrating tube such as a flow tube, keeps the connection state stable for a long period of time, and allows easy connection of explosion-proof terminals. Moreover, it is an object of the present invention to enable highly reliable wiring connection with a small number of man-hours.

[0012]

According to a first aspect of the present invention, there is provided an outer cylinder.
The outer tube supported at both ends and the fluid
Drives the center of the coaxial double tube consisting of an inner tube
Drive means and the inner tube through which fluid flows.
Has a pair of detecting means for detecting the Coriolis force to be used
In the straight tube type Coriolis flowmeter, the driving means and
The electric wires connected to the pair of detection means,
One piece of flexi glued to the outer tube wall
A flexible printed wiring board.
The bonding surface of the plate with the tube wall of the outer tube is
The surface is parallel to the driving direction in which the double shaft tube is driven.
It is.

[0013]

According to a second aspect of the present invention, in the Coriolis flowmeter according to the first aspect , a flexible printed wiring board is connected to a terminal plate of a terminal box provided outside the outer cylinder, and A predetermined section between the outer cylinder and the terminal box is sealed with an airtight material.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A Coriolis flow meter according to the present invention comprises:
It relates straight tube type, in particular, a coaxial double pipe and a straight pipe
And for the Coriolis flowmeter Ru are applied was. FIG. 1 is a cross-sectional view for explaining an embodiment of a Coriolis flowmeter according to the present invention. FIG. 1 (A) is a cross-sectional view taken along line AA of FIG. 1 (B), and FIG. FIG. 1 is a sectional view taken along the line BB of FIG. 1 (A), wherein 1 is an outer cylinder, 2 is an inner tube, 3 is an outer tube, 4 is a connection block, 5 is a coaxial double tube, 6
Is a drive unit, 7 and 8 are detection units, 9 is a flexible printed wiring board, 10 is a temperature sensor, 11 is a terminal box, 12 is a lid, 13 is a terminal plate, and 14 is a molding material. In the drawings subsequent to FIG. 1, parts having the same functions as those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1.

The straight pipe type Coriolis flowmeter shown in FIG. 1 has an outer pipe 1 (not shown) through which fluid flows and an outer cylinder 1 connected at both ends by connecting flanges 1a. ,
An inner tube 2 coaxial with the axis is inserted, and the inner tube 2 is fixed to the outer tube 1 at both ends so that a fluid to be measured flows into the inner tube 2. An outer tube 3 that forms a double pipe at a predetermined portion of the inner tube 2 is provided. The outer tube 3 is supported coaxially with the inner tube 2 by annular connection blocks 4 at both ends.

The coaxial double tube 5 is provided with a drive unit 6 for resonance driving at the center and detectors 7 and 8 at positions symmetrical to the drive unit 6. The drive unit 6 includes a cylindrical drive coil 6a and an iron core 6b inserted into the cylinder of the drive coil 6a. The iron core 6b has one end fixed to the inner tube 2. The detectors 7 and 8 have the same configuration, and are composed of cylindrical detection coils 7a and 8a and permanent magnets 8b and 9b around the cylindrical axis. A temperature sensor 10 for measuring the temperature of the inner tube 2 is attached to one end surface of the inner tube 2.

The drive coil 6a, the detection coils 7a and 8a, and the temperature sensor 10 are connected to one end of a flexible printed wiring board 9 having a two-dimensionally formed conductor in a heat-resistant resin, for example, a polyimide resin. They are connected at the branched portions 9a, 9b, 9c, 9d, respectively, and are fixed to the outer tube 3 via a silicone resin-based double-sided tape. The other end of the flexible printed wiring board 9 is fixedly wound around the outer tube 3 in the circumferential direction.

FIG. 2 is a perspective view of an essential part for explaining the state of attachment of the flexible printed wiring board shown in FIG. The flexible printed wiring board 9 includes branch portions 9a, 9
b, 9c, 9d, and branch portions 9a, 9b, 9c, 9d
Except for the above, the other part is adhered to the side surface of the outer tube 3 and has a small cross-sectional area as a whole, and a conductive wire having low bending rigidity and elasticity is formed inside.

FIG. 3 is a diagram for explaining the effect of vibration of the flexible printed wiring board adhering surface and the outer tube. The surface of the flexible printed wiring board 9 is shown in FIG.
Is a direction parallel to the vibration direction, FIG. 3 (B) is a direction perpendicular to the vibration direction, an arrow YY indicates a vibration direction of the outer tube 3, and a line XX is at right angles to the arrow YY line. Direction.

As shown in FIG. 3B, when the surface of the flexible printed wiring board 9 is stuck at right angles to the vibration direction line YY, the resonance vibration of the outer tube 3 is However, there is a possibility of fatigue fracture due to repeated vibrations of tension and compression due to
As shown in (A), by sticking to the surface parallel to the vibration direction YY, that is, to the side surface of the outer tube 3,
Since only minute vibrations parallel to the plane are applied, a large stress does not act on the flexible printed wiring board 9, and stable long-term connection of the conductor can be obtained.

The connection between the flexible tube 9 and each coil is described, for example, in the case of the drive unit 6. As shown in FIG. 4, the branch unit 9a and the drive coil 6a are connected to one end of the coil 6a, The conductor of the portion 9a is connected at a point 6d by soldering or the like.

Next, a connection structure in which the flexible printed wiring board 9 in the outer cylinder 1 is connected to the terminal plate 13 of the terminal box 11 provided on the outer wall surface side of the outer cylinder 1 will be described. As shown in FIG. 1, a flexible printed wiring board 9 in an outer cylinder 1 is provided.
Is passed through a terminal box support cylinder 1b provided outside the cylinder wall surface of the outer cylinder 1 as it is, and is led out into the terminal box 11. The terminal box 11 has an explosion-proof structure and has a packing 12a.
Is fixed by bolts 12b or the like. In the terminal box 11, a terminal plate 13 having an external connection terminal 13a is screwed on a support stand 11a formed integrally with the terminal box 11.

The flexible printed wiring board 9 is hermetically sealed and sealed in the terminal support cylinder 1b with a molding material 14 made of, for example, any of resin, glass, cement, and ceramics. Is completely sealed. The flexible printed wiring board 9 led into the terminal box 11 is connected to the corresponding terminals 13b of the terminal board 13 by soldering or the like, and is subjected to processing such as coating a vinyl tube. The space between the inner tube 2 and the outer tube 1 is an airtight container, in which an inert gas such as argon is sealed.

[0025]

According to the first aspect of the present invention , both ends are provided in the outer cylinder.
Supported outer tube and inner fluid flow
Driver that drives the center of a coaxial double tube made of
A step and a core acting on the inner tube through which the fluid flows.
A straight pipe type having a pair of detecting means for detecting the Rioli force
In the Coriolis flowmeter, the driving unit and the pair
The electric wires connected to the detecting means of the
-One flexible pre-adhesive bonded to the tube wall of the tube
And the flexible printed wiring board
The bonding surface of the outer tube to the tube wall is
Is a plane parallel to the driving direction in which it is driven, so the excitation resistance due to the wiring of the flow tube driven in resonance is reduced, the resonance characteristics are improved, and a signal with a high SN ratio is extracted with a small excitation force. Flexible and flexible
Low repetitive stress acting on the printed wiring board and durability
Excellent wiring is possible. In particular, the effect is great for a small straight tube Coriolis flowmeter.

[0026]

According to a second aspect of the present invention, in the Coriolis flowmeter according to the first aspect , a flexible printed wiring board is connected to a terminal plate of a terminal box provided outside the outer cylinder. A predetermined section between the outer cylinder and the terminal box is sealed with an airtight material, so that a single flexible printed wiring board can be used from the drive detection unit and the temperature sensor in the outer cylinder to a terminal board provided outside. Connection can be made, and reliability is improved. By sealing and fixing the flexible printed wiring board between the outer cylinder and the terminal box with a molding material, reliability can be improved and an explosion-proof structure can be obtained simply and at low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of a Coriolis flowmeter according to the present invention.

FIG. 2 is a perspective view of a main part for describing a state of attachment of the flexible printed wiring board shown in FIG.

FIG. 3 is a diagram for explaining the influence of vibration of a flexible printed wiring board attachment surface and an outer tube.

FIG. 4 is a diagram illustrating an example of connection between a driving coil of a driving unit illustrated in the drawing and a flexible printed wiring board.

FIG. 5 is a view for explaining a method of connecting electric wires and cables in a conventional explosion-proof structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... outer cylinder, 2 ... inner tube, 3 ... outer tube, 4 ... connection block, 5 ... coaxial double tube, 6 ... drive part,
7, 8 ... Detector, 9 ... Flexible printed wiring board, 1
0: Temperature sensor, 11: Terminal box, 12: Lid, 13: Terminal plate, 14: Mold material, 20: Flow meter outer cylinder side, 21:
Terminal box side, 22 ... molding material, 23, 24, 26, 27
... electric cable, 25 ... electric wire, 28, 29, 30 ... connection part.

──────────────────────────────────────────────────続 き Continued on the front page (72) Osamu Futagawa, Inventor 3-10-8, Kami-Ochiai, Shinjuku-ku, Tokyo Inside Oval Co., Ltd. (56) References JP-A-7-218310 (JP, A) Shokai Sho63 −29724 (JP, U) Japanese Utility Model 1-4223 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) G01F 1/84

Claims (2)

(57) [Claims] 1. An outer tube supported at both ends in an outer cylinder.
Coaxial double tube consisting of a tube and an inner tube through which fluid flows
Driving means for resonantly driving the center of the
A pair that detects the Coriolis force acting on the inner tube
In a straight tube type Coriolis flow meter having a detecting means of
Connected to the driving means and the pair of detecting means, respectively.
The electric conductor to be attached is adhered to the tube wall of the outer tube.
And one flexible printed wiring board
With the tube wall of the outer tube of the shibble printed wiring board
Of the coaxial double tube in the driving direction in which the coaxial double tube is driven.
Coriolis flowmeter characterized by parallel surfaces . 2. A flexible printed wiring board is connected to a terminal board of a terminal box provided outside the outer cylinder, and a predetermined section between the outer cylinder and the terminal box of the flexible printed wiring board is sealed with an airtight material. 2. A sealing method according to claim 1.
The Coriolis flowmeter described in 1.