JPH04204329A - Mass flow meter - Google Patents

Abstract

PURPOSE:To prevent the flexible operation of a sensor tube and absorb expansion due to temperature change by allowing the slide of tube supports which support the sensor tube in an extended direction to mainframes fixed to a pipe. CONSTITUTION:The inner cylinder portions 6d, 7d of mainframes (fixed) 6, 7 fixed to a pipe are fitted in the slide contact portions 4e, 5e of tube supports 4, 5 which support sensor tubes 2, 3, to support the supports 4, 5 in a slidable manner. As a result, the supports 4, 5 can be slid only in the extended direction (the arrow mark X) of the tubes 2, 3 to the mainframes 6, 7 so that the expansion of the tubes 2, 3 due to temperature change are absorbed and the deformation is prevented. In this case, O-rings 8, 9 are forcibly fixed to the slide contact portions 4e, 5e to prevent the leakage of measured fluid in a pipe line 15 to the outside. The tubes 2, 3, not in a bellows structure, are restricted in displacement to a radial direction because outer cylinder portions 4b, 5b and the inner cylinder portions 6d, 7d are fitted together, allowing stable vibration and flow instrumentation signals in order for accurate instrumentation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a mass flow meter, and more particularly to a mass flow meter configured to allow a flow rate to be measured to pass through a linear sensor tube.

Conventional technology The flow rate of the fluid to be measured depends on the type of fluid and its physical properties (density, viscosity, etc.)
, it is desirable to express it in terms of mass that is not affected by process conditions (temperature, pressure).

For this reason, various mass flowmeters are being developed that measure the mass flow rate of the fluid to be measured. There are flowmeters that directly measure the amount of water.

There are two types of conventional mass flowmeters of this kind: a type in which the sensor tube is linear, and a type in which the sensor tube is curved, such as a three-shape, an S-shape, or a U-shape. In general, curved shapes have problems such as high fluid pressure loss or a structurally large flow meter, while straight ones can keep the fluid pressure loss low but the fluid being measured is at a high temperature. In the case of fluids, the sensor tube stretches due to thermal expansion and becomes deformed within the flowmeter, creating a problem.

Therefore, as a solution to this mass flowmeter having a linear sensor tube, a flowmeter disclosed in Japanese Patent Application Laid-Open No. 63-30721 has been proposed. The mass flowmeter of this publication is configured to vibrate a linearly extending sensor tube in the radial direction and detect the displacement of the sensor tube due to Coriolis proportional to the flow rate. Furthermore, in order to solve the above problem, the sensor tube is provided with an accordion-shaped bellows near the flange having the inlet and outlet to allow thermal expansion in the axial direction of the sensor tube. A sufficiently heavy clamping ring is fixed to the bellows to avoid transmitting external vibrations to the vibrating part of the sensor tube.

Problems to be Solved by the Invention In the above-mentioned conventional mass flowmeter, the bellows portion not only absorbs the displacement of the sensor tube in the axial direction, but also bends, causing the vibrating portion of the sensor tube to shift in a radial direction other than the axial direction. If it becomes easier, there will be other issues. Especially in the case of the above publication, because the load of the heavy tightening ring acts on the bellows,
The bellows part may deform over time, which causes problems such as variations in the vibration characteristics of the sensor tube and unstable pickup output, making it difficult to accurately measure the flow rate.

Therefore, an object of the present invention is to provide a mass flowmeter that solves the above problems.

Means for Solving the Problems The present invention provides an upstream connecting portion connected to an upstream piping and a downstream connecting portion connected to a downstream piping so as to extend linearly in the piping direction. A mass flowmeter that has a sensor tube that vibrates and detects the displacement of the sensor tube due to the vibration, the end of the sensor tube or the end that is integrally connected to the sensor. The tube support that supports the tube is
The sensor tube is configured to be slidable in the extending direction of the sensor tube with respect to the main body fixed to at least either the upstream piping or the downstream piping, and to be fitted and supported by the main body.

The end of the sensor tube or the tube support that supports the end of the sensor tube can be slid only in the direction in which the sensor tube extends relative to the main body that is fixed to either the upstream piping or the downstream piping. By fitting and supporting the sensor tube in such a manner, it is possible to prevent the sensor tube from bending in the radial direction, and to absorb expansion and contraction in the extending direction due to temperature changes of the sensor tube, which is a straight tube, at the sliding portion. the result,
The output signal of the pickup becomes stable.

Embodiment FIG. 1 shows a vertical sectional view of a first embodiment of a mass flowmeter according to the present invention.

In the figure, the mass flow meter 1 is roughly connected to a pair of sensor tubes 2.
, 3, a tube support 4.5 that supports both ends of the sensor tubes 2 and 30, and a main body portion having flange portions (connection portions) 6a and 7a for attaching the mass flowmeter 1 to the upper and downstream pipes. (Fixed part) Consists of 6 and 7.

The pair of sensor tubes 2.3 are made of straight, corrosion-resistant metal tubes (for example, stainless steel tubes) that extend linearly in the fluid flow direction (direction indicated by arrow A in the figure). Incidentally, the sensor tube 2.degree. 3 made of a straight tube not only has less pressure loss when the fluid to be measured passes through it, but also is easy to manufacture since it does not need to be processed into a complicated shape.

The tube support 4.5 is a substantially bowl-shaped sliding member, and includes circular plate-shaped walls 4a, 5a fixed so that the end of the sensor tube 2.3 passes through them, and a wall 4a, Cylindrical outer cylinder parts 4b and 5 protrude in the A direction from the peripheral edge of 5a.
It consists of b.

Holes 4d and 5d into which the ends of the sensor tubes 2 and 3 are fitted and fixed are bored in the walls 4a and 5a, and both ends of the sensor tubes 2 and 3 are fitted into the holes 4d.

5d to more than half the depth of the holes 4d, 5d, and then fixed to the fixing parts 4a, 5a by welding or the like. The sensor tubes 2.3 are arranged parallel to each other between the tube supports 4,5.

The outer cylindrical portions 4b' and 5b are arranged in the axial direction or the sensor tube 2,
The wall portions 4a and 5 are aligned in the same direction as the extending direction of the wall portions 3
a, and its inner peripheral surface is a sliding contact portion 4e into which the main body portions 6 and 7 are slidably fitted.

It is said to be 5e.

The sensor tube 2.3 is provided with a vibrator 11 and a pickup 12.13, which will be described later, and is further provided with a tube support 4,
A cylindrical cover 14 is provided between the vibrator 11 and the pickups 12 and 13 from the outside.

The sensor tubes 2 and 3, the tube supports 4 and 5 for fixing them, and the vibrator 11. pickup 12,1
3. The cover 14 is assembled as described above to constitute the measuring section IO.

The main body 6 has an inlet 6b and a conduit 6C for the fluid to be measured in the center.
A flange portion 6a is provided around the inlet 6b. The flange portion 6a has a cylindrical inner tube portion 6d that protrudes toward the flow direction (direction A) and forms a conduit 6c.
Or is provided.

The main body part 7 also has the same structure as the main body part 6, and has an outflow lower b and a conduit 7C formed in the center, and a flange part 7a and an inner cylinder part 7.
d. Sensor tube 2.3 from pipe 6C
The pipe leading to the pipe 7C via the pipe constitutes the pipe 15 of the mass flowmeter 1. Furthermore, circumferential grooves 6e and 7e are formed on the outer surfaces of the inner cylinders 6d and 7d near their ends, respectively. And an O ring 8 is provided in each groove 6e, 7e.
゜9 is installed.

The outer diameter dimensions of the inner cylinder portions 6d and 7d are the same as those of the tube support 4.
．． The diameter is slightly smaller than the inner diameter of the outer cylinder portions 4b and 5b of No.5. Therefore, the main body parts 6, 7 are fitted into the inner cylinder parts 6d, 7d or the sliding contact parts 4e, 5e of the tube supports 4, 5 to slidably support the tube supports 4, 5. That is, the tube support 4.5 can slide relative to the main body 6° 7 only in the direction in which the sensor tube 2.3 extends (indicated by arrow X in the figure). Here, the ○ rings 8 and 9 are attached to the sliding contact portions 4 of the outer cylinder portions 4b and 5b when the main body portions 6.7 are fitted.
e and 5e to provide a liquid-tight seal so that the fluid to be measured in the pipe line 15 does not leak to the outside even if the tube support 4°5 slides.

The above-mentioned vibrator 11 has substantially the same configuration as an electromagnetic solenoid, and includes a coil section provided on the sensor tube 3 side,
It consists of a magnet section provided on the sensor tube 2 side, and when the coil section is energized, it drives the sensor tubes 2 and 3 in a direction toward or away from each other.

Like the vibrator 11, the pickups 12 and 13 are composed of a coil part and a magnet part, and obtain an output signal corresponding to the relative displacement of the sensor tubes 2 and 3 due to the vibrations of the sensor tubes 2 and 3.

When measuring the flow rate, the pair of sensor tubes 2 and 3 are connected to the vibrator 11.
It is excited with fluid flowing inside. still,
The fluid flowing in from the inflow port 6b is divided by the pair of holes 4d of the tube support 4, flows through the sensor tubes 2 and 3 at equal flow rates, and then merges after passing through the tube support 5 to flow downstream from the outflow lower b. Flows into side piping. In this way, when fluid flows through the vibrating sensor tubes 2 and 3, Coriolis is generated depending on the flow rate. Therefore,
An operation delay occurs between the inflow and outflow sides of the straight sensor tube 2.3, which causes a phase difference in the output signals of the pickups 12 and 13.

Since this phase difference is proportional to the flow rate, the pickup 12.
The flow rate is determined based on the phase difference between the output signals from 13.

In addition, the displacement caused by Coriolis generated in accordance with the flow rate passing through the vibrating sensor tube 2.3 is picked up 12.
．． Since the principle of flow rate measurement detected by 13 is the same as that of the previously filed mass flowmeter, detailed explanation of the flow rate measurement operation will be omitted here.

As shown in FIG.
．． 17 flange portion 16a.

17a, and are fixed with bolts and nuts with a gasket 18 interposed therebetween. The upper and downstream pipes 16 and 17 of the mass flow meter 1 are arranged in a straight line, and include a flange portion 16a,
The dimension between the end faces of 17a (excluding the thickness dimension of two gaskets 18) is fixed as . In this way, the mass flow meter has a main body part 6.7 having flange parts 6a and 7a,
Since it is connected to the pipes 16 and 17 fixedly arranged on the downstream side, in the mass flowmeter 1 having the above configuration, the measurement part IO is connected to the main body parts 6 and 7 on both sides in the direction indicated by the arrow X in FIG. As shown in , the sensor tube 2.3 is configured to be slidable in the extending direction of the sensor tube 2.3.

Next, the same dimension D1 of the end surfaces of both the main body parts 6.7 will be explained.

In FIG. 1, the main body 6 and the wall 4a of the tube support 4
Let D2 be the dimension of the gap previously provided between the main body portion 7 and the wall portion 5a, and let be the dimension of the gap provided between the main body portion 7 and the wall portion 5a. As shown in the figure, it can be seen that the ground-to-ground dimension D1 can be adjusted by the above-mentioned gap dimensions Dz and Ds. Here, FIG. 3 shows an enlarged view of the mass flowmeter 1 attached to the upstream and downstream pipes 16 and 17 as shown in FIG.
shows a state in which it is maximally separated from the main body part 6.

As shown in FIG.
Let D4 be the maximum gap size within a range that does not deviate from e. Even if the measuring part 10 slides to the maximum extent, the O-ring 8.
In order to prevent it from coming off the respective sliding contact portions 4e and 5e of 9, the sum of the above-mentioned gap dimensions (d) and (d) must be equal to or less than D4. And the gap dimension D2 defined as above. The same dimension D1 of the end face of the mass flowmeter 1 is determined by D3.

When the mass flowmeter 1 having the above configuration is attached to the fixed piping 16.17 with the predetermined face-to-face dimension D1, the measurement part IO
Gap dimension D2 shown in the figure. It becomes possible to slide in the extending direction of the Dh sensor tube 2.3.

As a result, when the fluid to be measured is a high temperature fluid, the measurement unit 10
The thermal expansion in the X direction that occurs in This will prevent it from happening.

Here, since the cover 14 constituting the measuring part 1O does not directly contact the high temperature fluid, the amount of displacement due to heat is different from that of the sensor tube 2.3. Therefore, one end of the cover 14 is fixed to the tube support 4 by welding, but the other end is configured to be slidable on the outer peripheral surface of the tube support 5 via a seal 19.

Furthermore, the sensor tube 2.3 differs from the conventional bellows structure in that it has outer cylindrical parts 4b, 5b and an inner cylindrical part 6d.

Since displacement in the radial direction of the tube is restricted by fitting with 7d, the vibration operation of the sensor tube is stabilized and fluctuations in the flow rate measurement output signal can be prevented, allowing more accurate flow rate measurement. can. Also, when the fluid to be measured is a low-temperature fluid, the sensor tube 2.
3 allows contraction within a range that does not exceed the gap dimension D4 from the normal temperature state, and has a similar effect when measuring the flow rate.

Furthermore, in the mass flowmeter 1 of this embodiment, the flange portion 6
Since the main body part 6.7 having the a and 7a parts is separate from the measuring part 10, the measuring part 10 becomes a common part even for various specifications with different flange part standards, which is advantageous in terms of manufacturing costs and product management. In addition, the flange portion 6a,
7a can be easily removed, and the inside of the sensor tube 2.3 can be easily cleaned.

In addition, the flange portions 16a of the upper and downstream piping 16.17
, 17a may vary depending on the installation site, but it can be easily adjusted by expanding and contracting the main body parts 6 and 7 on both sides, and can be easily installed.

In the above embodiment, both tube supports 4°5 and the main body 6.7 are slidable, but the present invention is not limited to this, and one tube support and the main body are completely fixed. Even in a mass flowmeter configured to allow sliding only between the other tube support and the main body, displacement in the extending direction due to heat of the sensor tube is absorbed and the same effect can be obtained. I'll come.

FIG. 4 shows a longitudinal sectional view of a second embodiment of the present invention.

Note that the vibrator and pickup provided on the sensor tube of the second embodiment are the same as those of the second embodiment. Since it has the same configuration as the example,
In the fourth @, the middle portion of the mass flowmeter 20 is omitted from illustration.

In the figure, a mass flowmeter 20 includes a pair of sensor tubes 21.
22, a vibrator (not shown) and a pickup (not shown) provided on the sensor tube 21, 22, a main body portion 23° 24 having a flange portion, and the sensor tube 21.
．． It is composed of a tube support 25 that supports one end of the tube 22, and a casing 26.

The main body part 23 has an inlet 23a formed in the center of an upstream flange part 23c, and a hole 23d into which a sensor tube 21, 22 is inserted between the inlet 23a and the downstream end.
23e has a wall portion 23b bored therein. One end of the sensor tube 21.22 is connected to the holes 23d, 2 in the wall 23b.
3e and is fixed by welding or the like. still,
The flow direction of the fluid to be measured is indicated by arrow A in the figure.

The other ends of the sensor tubes 21 and 22 have two holes 25a bored in the disk-shaped tube support 25.

25b and is similarly fixed by welding or the like. The sensor tubes 21, 22 are arranged parallel to each other between the wall 23b and the tube support 25.

The main body portion 24 has an outlet 24a and a conduit 24b formed in the center thereof, and a flange portion 24c is provided around the outlet 24a. The casing portion 24d forming the conduit 24b has an opening 24f into which the tube support 25 is fitted at the end opposite to the outlet 24a, and an opening 24f into which the tube support 25 is fitted is provided on the inner peripheral surface of the casing portion 24d. A sliding contact portion 24e whose diameter is slightly larger than the diameter is provided. Furthermore, the sliding contact part 2
An O-ring 27 is mounted in a groove recessed on the sliding surface of 4e.

The main body portion 24 has an opening 24f formed by a sliding contact portion 24e.
The tube support 25 is attached so as to be slidably fitted therein. The casing 26, which is a rigid cylindrical body, is welded between the main body parts 23 and 24, so that the main body part 24 is fixed to the main body part 23,
An integral mass flow meter 20 is formed. Therefore, the displacement of the tube support 25 in the radial direction is restricted by fitting with the main body 24, or the sensor tube 21, 22
Displacement is not regulated in the extending direction (indicated by arrow X in the figure).

When the mass flow meter 20 with the above configuration is installed on the upstream and downstream piping, one end of the sensor tube 21, 22 or the main body 2
3, that is, although it is fixed to the upstream piping,
Since the tube support 25, which is supported at the other end of the sensor tube 21, 22, is supported so as to be slidable relative to the other main body 24, that is, the downstream piping, it is not exposed to high or low temperatures. Sensor tube 21゜2 due to fluid measurement
Even if the sensor tubes 21 and 22 expand or contract, the sensor tubes 21 and 22 do not deform (and the sensor tubes 2
1.22 is the first because the displacement in the radial direction of the tube is restricted by the fitting between the tube support 25 and the main body 24.
As in the embodiment, the flow rate is measured accurately.

FIG. 5 shows a longitudinal sectional view of a portion of a third embodiment of the present invention.

In the mass flowmeter 30 of the third embodiment, the vibrator and pickup provided on the sensor tube have the same configuration as the mass flowmeter 1 of the first embodiment, and the main body 23 on the inflow side and The sensor tubes 31 and 32 are attached to the main body 23 using the mass flowmeter 2 whose structure is the second embodiment.
Since they have the same structure as 0, their illustration and description will be omitted.

In the same figure, the main body part 33 on the outflow side of the mass flowmeter 30 has an outflow port 33a and a conduit 33b formed in the center, and an outflow port 33a.
A downstream flange portion 33c is provided around the periphery. Further, at the end of the inflow side of the pipe line 33b (the flow direction of the fluid to be measured is indicated by arrow A), there is a support part 3 for the sensor tube 31, 32.
3d is provided.

A hole 33e having a slightly larger diameter than the sensor tube 31.32 is provided in the support portion 33d at a position where the sensor tube 31.32 is parallel to the other body portion that supports the sensor tube 31.32.

33f is drilled. and hole 33e.

Grooves 33g and 33h are formed around the entire circumference of the inner peripheral surface at substantially intermediate positions along the fluid flow direction on the inner peripheral surface of 33f, and O-rings 34 and 35 are attached to these grooves 33g and 33h, respectively. has been done. The upstream ends of the sensor tubes 31 and 32 are fixed to the main body 23 similarly to the mass flowmeter 20, or the downstream ends are connected to the holes 33e and 33.
f, and are supported on the support portion 33d of the main body portion 33 so as to be slidable in the direction of the arrow X. Further, the main body part 33 is fixed to the other main body part by a casing 36 which is a rigid body like the mass flowmeter 20.

Therefore, in the mass flowmeter 30 having the above configuration, the upstream end of the sensor tube 31.32 is slidable relative to the main body 33 in the extending direction of the sensor tube 31. Due to the diametric relationship between the holes 33e and 33f, the displacement of the sensor tubes 31, 32 is restricted in the radial direction of the tubes. Furthermore, the action of the O-rings 34 and 35 prevents the fluid to be measured from leaking to the outside.

As a result, even if high temperature or low temperature fluid passes through the sensor tube 31.32 as the fluid to be measured, the sensor tube 31.3 will not expand or contract in the extending direction of the sensor tube.
2 and the holes 33e and 33f, the sensor tubes 31 and 32 are not deformed, and the flow rate can be measured accurately as in the first embodiment.

Effects of the Invention As described above, the mass flowmeter of the present invention absorbs the displacement of the sensor tube that expands and contracts due to temperature changes in the measured fluid, whether the measured fluid is a high-temperature fluid or a low-temperature fluid. It is also possible to restrict radial displacement. Therefore, it is possible to prevent the sensor tube from being deformed due to the above expansion and contraction, and stress is generated in the sensor tube, and the sensor tube is not displaced in the radial direction as in the conventional bellows structure. This makes it possible to stabilize the vibration operation of the sensor tube and prevent variations in the output signal for flow rate measurement, making it possible to perform more accurate flow rate measurement.

Furthermore, since the displacement of the sensor tube is absorbed by the sliding movement of the sensor tube or tube support, the deterioration of the displacement absorbing part over time is delayed compared to the conventional system that uses bellows, which improves durability. It has the following features.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the first embodiment of the mass flowmeter according to the present invention, FIG. 2 is a diagram illustrating how to install the mass flowmeter shown in FIG. 1, and FIG. A diagram illustrating the end-to-end dimensions of a flowmeter, FIG. 4 is a partially omitted longitudinal sectional view of the second embodiment of the present invention, and FIG. 5 is a partially longitudinal sectional view of the third embodiment of the present invention. It is. 1.20.30...Mass flow meter, 2. 3. 21゜22.31.32...Sensor tube, 4.5゜25
...Tube support, 4a, 5a, 23b...Wall portion, 4e, 5e, 24e...Sliding contact portion, 6, 7.23°2
4.33... Main body, 6a, 23a... Inlet, 7
a, 24a, 33a...outlet, 6c, 7c. 15.24b, 33b... Pipeline, 8.9, 27°34
．． 35...0 ring, 10...measuring part, 11...
Vibrator, 12.13...Pickup, 26.36.
...Casing, 33d...Support part, 4d, 5d. 23d, 23e, 25a, 25b, 3
3e. 33f...hole. Patent applicant: Tokiko Co., Ltd.) Representative patent attorney: Tadahiko Ito Kini., 1.・And,'\,-,n--m; Patent attorney Kaneyuki Matsuura (--4c) Figure 3 □ 112'D41 Figure 4 Figure 5

Claims (1)

[Scope of Claims] A sensor tube provided to extend linearly in the piping direction between an upstream connecting portion connected to the upstream piping and a downstream connecting portion connected to the downstream piping. a mass flowmeter that vibrates the sensor tube and detects the displacement of the sensor tube due to the vibration, comprising: an end of the sensor tube, or a tube to which the end is integrally connected and supports the sensor tube; The support is
The main body fixed to at least either the upstream piping or the downstream piping is configured to be slidable in the extending direction of the sensor tube and to be fitted and supported by the main body. Features of mass flowmeter.