JPS6334409B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flow meter for measuring the mass flow rate of flowable substances, such as liquids, gases, and flowable solid substances, which utilizes the Coriolis force to indicate the mass flow rate.

The flow meter includes a conduit or flow tube that vibrates with flowing fluid material to be measured. The preferred embodiment of this flow meter includes two conduits arranged to form a tuning fork. This arrangement allows two tubes to vibrate with much less force than is required to vibrate a single conduit.

U.S. Patent No. Paule et al. as prior art
No. 2,635,462 discloses a densometer in which two hollow vibrating elements are configured to form two branches of a tuning fork. Each hollow vibrating element consists of a set of two concentric flow tubes for forming a flow path through the densometer. As each branch of the tuning fork vibrates, the natural frequency of this vibration changes depending on the density of the fluid material in the densometer. The feedback system to the vibration generator is adapted to measure the density of the material flowing through the densometer. A densometer that uses a U-shaped flow tube in the tuning fork branch allows the flowable substance to pass through an inlet in the stationary member into a first U-shaped loop, return through this loop to the stationary member, and form an interconnecting flow channel. into the second U-shaped tube through the second U-shaped tube.
It is configured to return to the fixation member through the shaped tube and finally exit through an outlet in the fixation member. In this densometer, vibrations in the first U-shaped tube cause resonance in the second U-shaped tube to reduce the power required to produce the necessary vibrations in the tuning fork structure.

An example of a Coriolis force type flowmeter is published in
This is disclosed in Japanese Patent No. 34683 (Patent No. 1366700), in which one U-shaped tube has two open ends fixed to a fixed member as half of a tuning fork. The other half of the tuning fork is formed by a metal bar member with one end fixed to a fixed member and the other end free to vibrate. The metal rod member and the U-shaped tube are vibrated by an electromagnet fixed to the free end of the rod member, and the intermediate or U-shaped portion of the tube is magnetically pushed or pulled.

The flowmeter of the present invention employs a pair of generally parallel loops fixed at their end portions to a support member, spaced apart and arranged in a tuning fork configuration. The use of these two substantially parallel and spaced apart looped conduits facilitates operation of the flow meter. In particular, when the flowmeter of the present invention is used to measure the mass flow rate of different fluids with different densities, the two loops are each filled with the same fluid, resulting in virtually equal masses, so that in this case the same resonant oscillations occur. It will have a number. Since the masses of the two loops remain virtually equal, these loop-shaped tuning forks eliminate the effects of undesirable vibrations (also known as "noise") in the support region, regardless of the fluid being measured. It will be erased efficiently.

In a preferred embodiment, one loop is attached to a vibrating or driving means so that the two loops vibrate in antiphase. These conduits are arranged so that the Coriolis couple produces opposite torques on each loop. The two loops are provided with sensing means for sensing torsional deflections of the vibrating, fluid-filled conduit due to Coriolis forces. Advantageously, the sensing means is a pair of sensors arranged opposite each other on or adjacent to the loop structure and substantially equidistant from the position of the drive means.
The signals from these sensors are processed by flow rate calculation means external to the loop, drive means and sensing means to provide a measure of mass flow rate.

In one embodiment, the two loops are connected outside the support member and at a distance from the driving means and the sensing means, so that all fluid flows through both loops before fluid exits the flow meter. go. This connecting means corresponds to a length of tube from the outlet of the first loop to the inlet of the second loop.

Further embodiments of the vibration loop have been implemented. That is, there is a type in which the loop is substantially U-shaped and curved toward each other in the vicinity of the support member rather than in the vicinity of the drive means to form the inlet and outlet portions. In one example, the loop is approximately circular. Still another example is a type in which the inlet and outlet portions of two substantially circular loops intersect with each other.

When a looped conduit is pivoted at its two open ends and rotated about the pivot, and a substance is flowed through the tube, a Coriolis couple acts on the inlet and outlet sections of the tube. This couple is reversed if the flow of material in these inlet and outlet sections is in opposite directions. This force couple twists the tube about an axis that lies in the plane of the looped conduit.

If two U-shaped or other loop-shaped tubes are oscillated back and forth instead of rotating, the couple will oscillate back and forth as the angular velocity reverses.

When two loop-shaped conduits are configured in the shape of a tuning fork,
Two tubes can be vibrated with much less power than required to vibrate a single looped conduit. When two tubes vibrate as a tuning fork, the tubes alternately approach each other to a minimum distance and then move away from each other to a maximum distance. It can therefore be seen that the vector of angular velocity of one tube is always opposite to the vector of angular velocity of the other tube. If the flow through the two tubes is the same, i.e. the flow in the inlet section is both in the first direction and the flow in the outlet section is both in the opposite direction, then the tubes have opposite angular velocities. Because of the vector, it is acted upon by an opposite torque.

Thus, the directed flow alternately twists the two tubes with opposite torques, so that, for example, the two inlet sections alternately twist toward each other and then away from each other during the aforementioned oscillations. .

One embodiment of the flow meter of the present invention is shown in a perspective view in FIG. FIG. 1 shows an inlet 12 and an outlet 13, a supporting or fixing member 9 and two vibrating looped conduits 1.
0 and 11 are shown. Drive blocks 30 and 31 are shown in the U-shaped portions of the looped conduits 10 and 11. Solenoid 32
A vibration means such as 31 is attached to the block 31 and a coupling means 33 is attached to the plunger of the solenoid 32 and extends through the block 31 to the block 30. Also, as shown in the figure, a sensor 4 is attached to one loop-shaped conduit.
Attached to the looped conduits 10 and 11 are cut-off blades 43, 44 and 45 attached to the looped conduits 0, 41 and 42 and the other looped conduit.

The mass of block 30 is equal to the sum of the masses of block 31 and solenoid 32 and is arranged so that the natural frequencies of loops 10 and 11 are the same.

The outlet 21 of the vibrating loop conduit 10 is connected to the vibrating loop conduit 11 by a connecting means 20, such as a flexible or rigid connector, as shown.
It is connected to the entrance 19 of. For this reason, entrance 1
2 flows into the loop conduit 10, around the loop conduit 10, to the outlet 21 of this loop conduit, and through the connecting means 20 to the inlet 19 of the loop conduit 11. The substance to be measured then flows through the second loop conduit to the outlet 13 of the flow meter. The flow in the inlet sections 16 and 23 and the flow in the outlet sections 17 and 25 are in the same direction.

The vibrating loop conduit 10 has an inlet section 16 and an outlet section 17 spaced apart from each other and connected by an intermediate section 18 . The inlet section 16 and the outlet section 17 have curved sections 14 and 1 as shown.
5 may be provided. Similarly, the looped conduit 11 has an inlet section 23, an outlet section 25 and an intermediate section 24. The inlet section 23 and the outlet section 25 may also be provided with curved sections 22 and 26 as shown.

Solenoid 32 sends electrical pulses to terminals 34 and 3.
5. terminal 34
and 35 is applied to the loop-shaped conduit 1
The solenoid 32 is actuated so that 0 and 11 are pulled together by the coupling means 33. At the end of the electrical pulse the spring action of the two looped conduits 10 and 11 pulls the loops apart. Therefore, the frequency of vibration of the tube can be controlled by controlling the frequency of the electrical pulses applied to terminals 34 and 35.

Electromagnets can be used to alternately attract and pull the loop conduits 10 and 11 away from each other in order to impart vibrations to the loop conduits. Alternatively, an electric motor or other type of vibrating means can be used to pull one side in only one direction or to alternately pull and push the loops to produce the desired tuning fork-like vibrations.

It can be seen that these looped conduits oscillate about the Z axis as indicated by arrows 52 and 53. These vibrations and the flowable material flowing through the tube create a Coriolis couple that causes the looped conduit 10 to
and 11 around the X axis.

It can be seen that the looped conduits 10 and 11 act as branches of a tuning fork. The frequency of the electrical pulses applied to terminals 34 and 35 of solenoid 32 is equal to that of the tuning fork formed by loop conduits 10 and 11 when the loop conduits are empty or filled with a known substance, such as water. It is the natural frequency. It can therefore be seen that applying a force to blocks 30 and 31 by solenoid 32 causes vibrations in the tuning fork formed by looped conduits 10 and 11. These vibrations occur as shown by arrows 54 and 5 when the fluid material is flowing in the loop.
A Coriolis force is generated which produces a torsional vibration denoted by 5.

Sensor elements represented by sensor 42 and cut-off blade 45 are used to measure the deflection of looped conduits 10 and 11.

It can be seen that the natural frequency of a vibrating conduit varies depending on the density of the material flowing within the conduit. If we choose the natural frequency when water is in loops 10 and 11 as a constant frequency, loops 10 and 11
The density of the unknown substance to be measured within the oscilloscope will cause the frequency to change from the selected constant frequency. Thus, when the loops 10 and 11 are caused to vibrate longitudinally by the solenoid 32 at a predetermined frequency and with a constant amplitude, the required excitation force of the solenoid 32 varies according to the density of the material flowing within the loops 10 and 11. I will do it.

The sensor 42 and the cutoff blade 45 are configured to sense when the amplitude of vibration reaches a certain value. An automatic gain control or feedback loop including a sensor 42 as known in the art controls and measures the power of the electrical pulses supplied to terminals 34 and 35 to maintain the longitudinal amplitude of the vibrations at a desired level and constant frequency. can be used to

Coriolis deflection or torsional vibration of the looped conduits 10 and 11 about the X-axis as shown in FIG. 1 can be measured by sensors 40 and 41 as shown in FIGS. 2a-2g. .

Centers 40 and 41 are, in one preferred embodiment, light isolator type devices that constitute saddles. It has a light source on one side of the saddle and a light sensitive switch, such as a phototransistor, on the other side of the saddle. The light isolator type device is turned off by placing a plate between the saddle's light sensitive switch and the light source. Such a light isolator type device is the GEH13A1.

A phase difference occurs between the outputs of the two sensors that is proportional to the Coriolis couple that turns each sensor on and off.

In a preferred embodiment, the sensor is arranged to be off when the sensor is in a neutral or rest position, as indicated by the line 61 in Figures 2a-2g. Line 60 in Figures 2a-2g indicates the minimum spacing that occurs when the looped conduits 10 and 11 are pulled to their closest point during vibration. line 62
is the maximum position reached by the sensor when the looped conduits 10 and 11 reach the point of maximum separation during vibration. As shown in FIGS. 2a, 2d, and 2g, the intermediate portions 18 and 24 of the looped conduit exhibit a Coriolis couple at these points because the angular velocity of vibration is zero at the maximum and minimum points. I don't accept it.

FIG. 2a shows that sensors 40 and 41 are off because blocking blades 43 and 44 block the sensor's light flux. In figure 2b,
Intermediate portions 18 and 24 have moved outwardly in the directions indicated by arrows W ₁ and W ₂ . It will be appreciated that the leading edges of intermediate portions 18 and 24 reach line 61 due to the Coriolis couple that produces opposite torques. This causes the cutoff blade 44 to retract from the sensor 41 a sufficient distance to turn the sensor 41 on. However, the opposite torque causes the cutoff blade 43 to keep the sensor 40 off. 2nd c
The figure shows the trailing edge of intermediate portions 18 and 24 passing through line 61 turning sensor 40 on.
Figure 2d shows that intermediate portions 18 and 24 have reached their maximum separation, turning on sensors 40 and 41.

Figure 2e shows the intermediate portions 18 and 24 moving inwardly as indicated by arrows W ₁ and W ₂ .
The leading edges of intermediate portions 18 and 24 pass slightly through line 61 to turn sensor 41 off. The trailing edges of intermediate portions 18 and 24 have not yet passed through line 61 to keep sensor 40 in the on position. Figure 2f shows that intermediate portions 18 and 24 have moved inwardly enough to switch sensor 40 to the off position. FIG. 2g again shows that looped conduits 10 and 11 have reached their minimum separation point, keeping sensors 40 and 41 in the off position.

FIG. 3 is a chart showing the states of the sensors 40 and 41 as shown in FIGS. 2a to 2g. It can be seen that there is a phase difference between sensors 40 and 41. This phase difference can be detected electrically and increases over time as the flow rate through the looped conduits 10 and 11 increases.

FIG. 4 shows another preferred embodiment of a flowmeter of the type in which two loop-shaped conduits are vibrated in a tuning fork shape according to the same principle as in FIG. A circular vibratory loop conduit 71 is held on a support or fixed member 70 . Sensors 40 and 41, similar to those shown with the same reference numerals in FIG. 1, are attached to looped conduit 71. It is shown that drive means, such as a solenoid 32, are provided at the free end of the circular loop conduit 71 to vibrate the two loop conduits alternately.

FIG. 5 shows another preferred embodiment of a circular loop conduit 76. The support or fixation member 75 is an extension 80 of the looped conduit 76.
and 81 have fixed attachment portions 78 and 79 extending therethrough. The looped conduit 76 is secured as shown at 77 such that the two looped conduits intersect with each other. The embodiment of FIG. 5 above may be fitted with sensors and drive means as shown in FIGS. 1 and 4. It should be appreciated that Figures 4 and 5 depict one loop of the flow meter, which preferably includes two loops of tuning fork configuration.

Various modifications other than the embodiments described above will occur to those skilled in the art. Those skilled in the art will understand that such modifications and adaptations fall within the scope of the present invention.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a flowmeter according to an embodiment of the present invention, showing two U-shaped or loop-shaped conduits, an electromagnetic drive means and a sensor means; FIGS. 2a to 2g; FIG.
The figure shows the change in the sensor attached to the conduit when two loop-shaped conduits vibrate, and Figure 3 shows the change in the sensor attached to the conduit.
Charts of the sensor states shown in Figures to Figures 2g; Figure 4 is a diagram showing another embodiment of the loop-shaped conduit;
FIG. 5 is a diagram showing yet another embodiment of the conduit. 9, 70, 75...Supporting member, 10, 11, 7
1, 76... Loop-shaped conduit, 16, 23... Inlet portion, 17, 25... Outlet portion, 32... Driving means, 40, 41... Measuring means (sensor).

Claims (1)

[Scope of Claims] 1. Conduit means, driving means for vibrating the conduit means, detection means for detecting torsional deflection due to Coriolis force of the vibrating conduit means filled with fluid, and measuring means for measuring mass flow rate as a function of force-based torsional deflection, the conduit means having each loop fixed at its inlet and outlet portions to a common support member; A flow tube comprising two substantially parallel loops attached to each other, so that when the driving means acts on the two loops, these loops vibrate in a tuning fork shape. Coriolis force flowmeter for measuring the mass flow rate of fluid flowing through. 2. The flow meter according to claim 1, wherein the inlet and outlet portions of the loop pass through the fixedly attached support member,
and an outlet of one loop is connected to an inlet of the other loop outside the support member and spaced apart from the drive means and the measurement means. 3. A Coriolis force type flow meter according to claim 1 or 2, wherein the two loops are substantially U-shaped, and the inlet portion and the outlet portion are bent with respect to each other. Total. 4. The Coriolis force flowmeter according to claim 1 or 2, wherein the two loops are substantially circular. 5. The Coriolis force type flowmeter according to any one of claims 1 to 4, wherein the inlet portion and the outlet portion of each loop are provided so as to intersect with each other.