JPH0499919A - Mass flowmeter - Google Patents

Abstract

PURPOSE:To correctly measure the flow rate by providing a displacement restricting member for restricting the vibrating components in the other directions than the vibrating direction detected by a pickup. CONSTITUTION:The displacement in the X direction corresponding to the vibration by a vibrating device 14 is detected by pickups 15, 16 of a mass flowmeter 1. There are displacement restricting members 17, 18 supported between sensor tubes 6 and 7 in a direction orthogonal to the extending direction of the tubes 6, 7 so as to restrict the relative displacement of the tubes 6 and 7 in the other directions than the X-direction. Therefore, although the displacement of the tubes 6 and 7 in the X direction may be brought about where the members 17, 18 are present, the displacement in the Y direction is restricted. Accordingly, the vibrating components in the other directions than the X direction are restricted among the whole displacement generated by the external vibration in the radial direction of the tubes 6 and 7. The tubes 6, 7 can be vibrated only in the X direction, and the pickups 15, 16 can detect the relative displacement of the vibrating tubes 6, 7. The flow rate is thus correctly measured.

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 fluid to be measured to pass through a 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.

An example of this type of conventional mass flowmeter is the
There is a flowmeter disclosed in Japanese Patent Nos. 1-174814.

The mass flowmeter disclosed in this publication uses a vibrator to vibrate the central part of the linearly extending sensor tube in the radial direction in order to reduce pressure loss when the measured fluid passes through it. The sensor tube is configured to detect displacement of the sensor tube using a pickup.

Furthermore, the excitation method in the straight sensor tube is as follows:
A substantially central portion of the sensor tube is excited in the radial direction to vibrate the sensor tube in a first-order vibration mode. In this way, when fluid flows inside the vibrating sensor tube,
Coriolis occurs in opposite directions in the upstream pipe line and the downstream pipe line, using the vibrating portion as a branch point, and a secondary vibration mode is generated in the straight sensor tube. Therefore, in the above mass flowmeter, a time difference occurs between the output of the pickup that detects the displacement between the upstream pipe line and the downstream pipe line due to the frequency of the secondary vibration mode, and the flow rate is measured based on this time difference. .

Problem to be Solved by the Invention In the mass flowmeter having the straight sensor tube described above,
Since the straight pipe is configured to vibrate in the radial direction of the straight pipe, the structure is such that the straight pipe is easily vibrated not only in the direction of vibration by the vibrator but also in other radial directions. Therefore, when external vibrations propagate to the mass flowmeter, the straight sensor tube vibrates in both radial and 360° directions, making it susceptible to external vibrations and becoming a source of vibrations in the surrounding area. Accurate flow measurement could not be performed if various devices were installed.

Therefore, the present invention has a configuration in which the straight pipe is difficult to vibrate in a direction different from the direction of vibration by the vibrator.
It is an object of the present invention to provide a mass flowmeter that solves the above problems.

Means for Solving the Problems The present invention provides a conduit having a straight pipe portion extending linearly between an inlet through which a fluid to be measured flows in and an outlet through which the fluid to be measured flows out; a vibration exciter that vibrates the straight pipe section in the radial direction, and a pickup that detects the displacement of the straight pipe section in the radial direction due to the vibration of the straight pipe section, the mass flowmeter having the following: In order to be able to be displaced only in the detection direction and to restrict displacement of the straight pipe portion in other directions, a displacement regulating member is provided that expands and contracts only in the displacement detection direction.

By providing a displacement regulating member that expands and contracts only in the displacement detection direction so that the working pipe can be displaced only in the direction of the radial force to be detected by the pickup, and to restrict the displacement in other directions. Even when external vibrations are applied, the pipe line is less likely to vibrate in directions other than the vibration direction, and the vibration of the pipe line during flow rate measurement is stabilized, making it possible to perform flow rate measurement satisfactorily.

Embodiment FIGS. 1 and 2 show an embodiment of a mass flowmeter according to the present invention.

In each figure, the mass flow meter 1 is a sealed box-shaped casing 2.
A conduit 3 through which the fluid to be measured passes is provided inside. The conduit 3 is formed of an inflow pipe 5 having an inflow port 5a, a pair of straight sensor tubes (straight pipe portions) 6 and 7, and an outflow pipe 8 having an outflow port 8a.

The inflow pipe 5 has a flange 5b connected to an upstream pipe (not shown) at the inflow side end, and the other end of the inflow pipe 5 is formed inside the casing 2 by penetrating the side wall 2a of the casing 2. It extends into chamber 2b.

Reference numeral 9 denotes an inflow side manifold, which has an upstream side connection port 9a to which the inflow pipe 5 is connected and fixed, and downstream side connection ports 9b and 9c to which the upstream end of the sensor tube 67 is connected and fixed.

The upstream connection port 9a and the downstream connection ports 9b and 9c communicate with each other via branch channels 9d and 9e.

Reference numeral 10 denotes an outflow side manifold, which has a pair of connection ports 10a, 10 to which the downstream end of the sensor tube 6.7 is connected and fixed.
b, and a connection port 10c to which the upstream end of the outflow pipe 8 is connected.
and has. Moreover, a pair of connection ports 10a are provided in the outflow side manifold 10.

A flow path 10d communicates the connection port 10b with the connection port 10c.

10e is bored.

The pair of sensor tubes 6.7 are straight pipes that extend linearly in the fluid flow direction (inflow direction), and are provided in parallel between the inflow side manifold 9 and the outflow side manifold 10. The sensor tube 6.7 made of a straight pipe is easy to manufacture because not only the pressure loss is small when the fluid to be measured passes through it, but also there is no need to process it into a complicated shape.

The upstream end of the outflow pipe 8 is connected and fixed to the connection port 10c of the outflow manifold 10, and the downstream end penetrates the side wall 2c of the casing 2 and protrudes downstream (direction A).

Note that an outflow port 8a is opened at the downstream end of the outflow pipe 8, and a flange 8b connected to a downstream pipe (not shown) is provided on the outer periphery of the outflow port 8a.

The casing 2 holds the inflow pipe 5 and the outflow pipe 8 and connects the pipe line 3
is held in the chamber 2b, and has sufficient rigidity so that external vibrations are not transmitted to the pipe line 3.

A vibrator is installed between the pair of sensor tubes 6.7 installed between the inflow side manifold 9 and the outflow side manifold 10 to vibrate the center portions of the pair of sensor tubes 6.7 in the radial direction (X direction). 14, and pickups 15 and 16 are disposed above and downstream of the vibrator 14 to detect displacement due to vibration of the sensor tube 6.7. The vibrator 14 has substantially the same configuration as an electromagnetic solenoid, and consists of a coil portion 14a provided on the sensor tube 6 side and a magnet portion 14b provided on the sensor tube 7 side, and when the coil portion 14a is energized, the sensor The tubes 6, 7 are driven in the X direction toward or away from each other.

The pickup 15.16 is composed of coil parts 15a, 16a and magnet parts 15b, 16b, similar to the vibrator 14, and outputs a signal corresponding to the relative displacement of the sensor tube 6.7 due to the vibration of the sensor tube 6.7. get.

When measuring the flow rate, the pair of sensor tubes 6.7 are connected to the vibrator 14.
It is excited with fluid flowing inside. still,
The fluid flowing into the pipe line 3 from the inlet port 5a is divided into two by the branch channels 9d and 9e of the inflow side manifold 9, and then flows into the sensor tube 6.
．． 7 at the same flow rate, and further merges at the flow paths 10d and 10e of the outflow side manifold 10, and flows out from the outflow pipe 8 to the downstream piping. In this way, when fluid flows through the vibrating sensor tube 6.7, Coriolis is generated in accordance with the flow rate. Therefore, an operation delay occurs between the inflow side and the outflow side of the straight sensor tube 6.7, resulting in a phase difference between the output signals of the pickups 15 and 16. Since this phase difference is proportional to the flow rate, the flow rate can be determined based on the phase difference between the output signals from the pickups 15 and 16.

The principle of flow rate measurement in which the pickup 15.16 detects the displacement caused by Coriolis generated in response to the flow rate passing through the vibrating sensor tube 15.16 is the same as that of the previously filed mass flowmeter, so it will not be described here. A detailed explanation of the flow rate measurement operation will be omitted.

In this way, in the mass flowmeter 1, the X
The pickups 15 and 16 are configured to detect displacement in the X direction corresponding to the vibration in the same direction.

17.18 is a displacement regulating member for regulating relative displacement between the sensor tubes 6.7 in directions other than the X direction, and extends in a direction perpendicular to the extending direction of the sensor tubes 6.7 (X direction in the figure). It is mounted between parallel sensor tubes 6, 7 in the same orientation. One displacement regulating member 17 is provided between the vibrator 14 and the upstream pickup 15, and the other displacement regulating member 18 is provided between the vibrator 14 and the downstream pickup 1.
6.

FIG. 3 is an enlarged perspective view of the displacement regulating member 17 (the displacement regulating member 18 has a similar structure). The displacement regulating member 17 is formed of a thin metal plate, and as shown in the same figure, the sensor tube 6.7 is inserted through the tube support portion 17a, '17.' to which the sensor tube 6.7 is welded.
b at both ends, and a tube support part 17 in the middle part.
A 7-shaped contracted portion 17c is provided continuously from a and 17b.

This displacement regulating member 17 has two inclined parts 17d that constitute a contracted part 17c with respect to the X direction of the sensor tube 67.
, 17e can be displaced and expanded/contracted to change their inclination angles, so the displacement of the sensor tube 6.7 in the X direction is not hindered. However, for example, in response to displacement in the
It has a configuration that can be displaced only in the direction, and the sensor tube 6
．． Since the sensor tubes 7 are firmly fixed on the tube supports 17a and 17b in a non-rotatable state, the displacement of the pair of sensor tubes 6.7 in the X direction is restricted.

Further, in the radial direction of the sensor tube 6.7, displacement in directions other than the X direction is also restricted by the displacement regulating member 17 in the same manner as the displacement in the X direction. Therefore, the displacement regulating members 17 and 18 are configured so as not to be a load on the vibrator 14.

Therefore, in FIG. 1, the displacement regulating member 17 with the above configuration.
Due to the above-mentioned action, displacement in the X direction is possible between the sensor tubes 6 and 7 where the sensor tube 18 is provided, but displacement in the X direction is restricted. As a result, vibration components other than those in the X direction among all radial displacements generated between the sensor tubes 6 and 7 due to external vibrations are suppressed. Therefore, the sensor tube 6.7 can only vibrate in the X direction, and the pickup 15.16 can detect the relative displacement of the vibrating sensor tube 6.7. Sensor tube by Coriolis proportional to 6.7
Only the displacement of can be detected.

Further, in the above embodiment, a pair of displacement regulating members 17, 18 are provided between the sensor tubes 6, 7, but for example, as shown by the dotted chain line in FIG. Alternatively, four displacement regulating members may be provided.

Next, FIG. 4 shows a modification of the displacement regulating member.

The displacement regulating member 19 shown in FIG. It is configured to expand and contract only in the X direction of .7.

Even when using the displacement regulating member 19 with the above configuration, relative displacement in the X direction between the sensor tubes 6 and 7 is possible, and all displacements of the piston member 20 in directions other than the X direction, including the X direction in the figure, are restricted. Therefore, the same effects as those of the displacement regulating members 17 and 18 described above can be obtained.

Moreover, the displacement regulating member of the present invention may be any other than the above-mentioned two embodiments as long as it is configured to expand and contract only in the X direction of the sensor tube 6.7.

Furthermore, in the above embodiment, two sensor tubes 6
．． Although the relative displacement between 7 and 7 was regulated,
The present invention is not limited to this, and may be a mass flow meter using only one sensor tube.

FIG. 5 shows an example of a mass flowmeter having one sensor tube, which is based on the principle described above.

In the mass flowmeter 30 shown in the figure, the sensor tube 35 is vibrated in the X direction with respect to the vibrator 32 or the casing 31,
The pickups 33 and 34 detect the displacement of the sensor tube 35 with respect to the casing 31. The displacement regulating members 36 and 37 having the above-mentioned 7-shaped contracted portion fix the sensor tube 35 at one end and the casing 3 at the other end.
1 and is provided on the X direction. Incidentally, the vibrator 32 and the picker knobs 33 and 34 in this embodiment are as follows:
Vibrator 14 and pickquats 15, 16 shown in FIG.
It has the same configuration as .

Even in the mass flow meter 30 having such a configuration, the sensor tube 35 can be displaced only in the X direction with respect to the casing 31 even if external vibrations act due to the action of the displacement regulating members 36 and 37. Since the casing 31 has sufficient rigidity, the pick-ups 33 and 34 provided on the same casing 31 can detect only the displacement of the sensor tube 35 in the X direction due to the Coriolis force. .

Further, although the above embodiment has been described using a straight sensor tube as an example, the displacement regulating member may be provided on a straight pipe portion of a sensor tube having a shape other than this.

Effects of the Invention As described above, the mass flowmeter of the present invention is equipped with a displacement regulating member that regulates vibration components in directions other than those detected by the pick-up. It is possible to prevent the tube portion from vibrating in directions other than the excitation direction, and it is possible to accurately detect the displacement of the sensor tube due to Coriolika according to the flow rate. Therefore, noise caused by external vibrations is removed and flow rate measurement can be performed more accurately.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of a mass flowmeter according to the present invention, FIG. 2 is a vertical cross-sectional view taken along line I[-II in FIG.
FIG. 4 is a perspective view showing an enlarged displacement regulating member, FIG. 4 is a perspective view showing a modification of the displacement regulating member, and FIG. 15 is a cross-sectional view of another modification of the present invention. ■, 30...Mass flow meter, 2, 31...Casing, 3...Pipeline, 6,7.35...Sensor tube,
9... Inflow side manifold, IO... Outflow side manifold, 14.32... Vibrator, 15, 16, 33.
34...Pickup, 17, 18, 19, 36.3
7... Displacement regulating member, 17a, 17b... Tube support member, 17c... Contraction part.

Claims (1)

[Claims] A pipe line having a straight pipe section extending linearly between an inlet where a fluid to be measured flows in and an outlet where the fluid to be measured flows out, and an exciter that vibrates the straight pipe part in a radial direction. , a pickup for detecting displacement in the radial direction of the straight pipe section due to vibration of the straight pipe section, wherein the straight pipe section is displaceable only in the direction in which displacement is detected by the pickup; A mass flowmeter comprising a displacement regulating member that expands and contracts only in the displacement detection direction in order to regulate the displacement of the straight pipe section.