JPH0835872A - Vibrating measuring device - Google Patents

Abstract

PURPOSE:To provide a vibrating measuring device so constituted as to obtain larger Coriolis force by increasing the amplitude of a sensor tube. CONSTITUTION:The sensor tubes 8, 9 of a mass flowmeter 1 are connected at the ends 8a, 9a of inflow side to bellows 6, 7 and at the other ends 8b, 9b of outflow side to flow inlets 10a, 10b of an outflow side manifold 10. When the sensor tubes 8, 9 are vibrated by a vibrator 12, the bellows 6, 7 elastically deform, the amplitudes of one ends 8a, 9a of the sensor tubes 8, 9 become large and the angular velocity also becomes large, In proportion to the larger amplitude, larger Coriolis forces are generated at the sensor tubes 8, 9. Also, the phase difference between the detection signal of the pickup 13 and the excitation signal of the vibrator 12 is proportional to the flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration type measuring device,
In particular, the present invention relates to a vibration type measuring device configured to efficiently detect displacement of a sensor tube due to generation of Coriolis force proportional to flow rate.

[0002]

2. Description of the Related Art As a vibration type measuring device for measuring a physical quantity of a fluid by vibrating a pipe through which the fluid flows, there is, for example, a Coriolis mass flowmeter or a vibrating density meter.

In this Coriolis mass flowmeter, a sensor tube through which a fluid to be measured passes is vibrated in a radial direction by a vibrator, and a displacement of the sensor tube due to a Coriolis force proportional to the flow rate is detected by a pickup. There is. The vibrating density meter also has the same structure as the Coriolis mass flow meter, and the sensor tube vibrates at a frequency according to the density of the fluid to be measured.

For example, in the case of a mass flow meter, a pair of sensor tubes are vibrated at a natural frequency in a state in which a fluid is filled to measure the inside of the sensor tubes, and the fluid is caused to flow into the sensor tubes so that The flow rate of the fluid is measured by detecting the time difference of the vibration of the sensor tube caused by the Coriolis force generated in the fluid flowing through.

In order to perform stable measurement in such a mass flowmeter, it is important that the sensor tube vibrates stably at the above natural frequency.

Therefore, in the Coriolis mass flowmeter,
For example, a pair of sensor tubes are extended in parallel, a shaker is placed horizontally in the middle of the pair of sensor tubes in the longitudinal direction, and a support member that fixedly supports both ends of the pair of sensor tubes is placed horizontally. It was An inflow-side pickup for detecting displacement of the inflow side into which the fluid to be measured flows is provided between the vibration exciter and the upstream side support member, and the inflow side pickup is provided between the vibration exciter and the downstream side support member. An outflow-side pickup for detecting a displacement on the outflow side into which the fluid to be measured flows is provided.

Therefore, in the Coriolis mass flowmeter, 1/4, 3/4 of the total length which is intermediate between the intermediate position of the sensor tube provided with the vibrator and both ends fixed to the supporting member.
The flow rate of the fluid to be measured flowing through the sensor tube is calculated based on the detection signal from the pickup that detects the displacement of the length position.

[0008]

However, in the prior art, as described above, the pickups on the inflow side and the outflow side are configured to detect the displacements of the length positions of 1/4 and 3/4 of the sensor tube. The displacement (amplitude) of the tube was small. Therefore, in order to secure the detection accuracy, it is necessary to use a highly accurate displacement detection sensor (for example, a laser displacement meter) in the pickup, and in that case an expensive pickup is used, resulting in a manufacturing cost. There is a problem that it becomes more expensive.

Further, conventionally, the measurement accuracy is improved by lengthening the sensor tube and increasing the amount of displacement detected by the pickup. Therefore, there is a problem that the sensor tube becomes long and the entire device becomes large.

Therefore, an object of the present invention is to provide a vibration type measuring device which solves the above problems.

[0011]

The invention according to claim 1 is
A sensor tube through which a fluid to be measured flows, a flexible conduit that is connected to one end of the sensor tube and supports one end of the sensor tube so as to allow radial displacement of the sensor tube, and a sensor tube of the sensor tube. A fixed member that fixedly supports the other end, a vibrator that vibrates and vibrates one end of the sensor tube, and a pickup that detects displacement of one end of the sensor tube due to generation of Coriolis force. Is characterized by.

According to the second aspect of the present invention, the sensor tube through which the fluid to be measured flows is connected to both ends of the sensor tube so as to support the sensor tube so as to allow the radial displacement of the sensor tube. A flexible tube, a fixing member that fixedly supports an intermediate position of the sensor tube, a vibrator that vibrates and vibrates both ends of the sensor tube, and displacement of both ends of the sensor tube due to generation of Coriolis force. And a pickup for detecting the.

[0013]

According to the first aspect of the invention, one end of the sensor tube connected to the flexible conduit is vibrated by the vibrator, and the displacement of the one end of the sensor tube is detected by the pickup. The conduit is elastically deformed to increase the amplitude at one end of the sensor tube and also increase the angular velocity. A Coriolis force larger than that amount is generated in the sensor tube, and even if a disturbance occurs, the Coriolis force is large and the influence of the disturbance is small.

According to the second aspect of the invention, both ends of the sensor tube connected to the flexible conduit are vibrated by the vibration exciter and the displacement of the both ends of the sensor tube is detected by the pickup, so that the flexible tube is flexible. The conduit is elastically deformed to increase the amplitude at both ends of the sensor tube and also increase the angular velocity. A Coriolis force larger than that amount is generated in the sensor tube, and even if disturbance occurs, the Coriolis force is large,
The influence of disturbance is reduced.

[0015]

1 to 3 show a Coriolis mass flowmeter as a first embodiment of a vibration measuring apparatus according to the present invention.

As the vibration type measuring device, there are a Coriolis type mass flowmeter and a vibration type density meter. Since the Coriolis mass flowmeter has substantially the same configuration as the vibration density meter, the mass flowmeter will be described in detail in this embodiment.

In each of the drawings, a mass flowmeter 1 is constructed by inserting a pipe 3 through which a fluid to be measured passes in a closed casing 2.
The pipe line 3 includes an inflow pipe 4, an inflow side manifold 5, a pair of bellows 6 and 7, a pair of sensor tubes 8 and 9,
It is formed of an outflow side manifold 10 and an outflow pipe 11.

The inflow pipe 4 is fixed by welding or the like while being inserted into the inflow port 5a of the inflow side manifold 5.
The pair of bellows 6 and 7 are fixed to each other by welding or the like while being inserted into the outlets 5b and 5c of the inflow side manifold 5.

Since the pair of sensor tubes 8 and 9 are formed of straight metal pipes, they are relatively easy to process and the pressure loss of the fluid to be measured is reduced.
Further, the sensor tubes 8 and 9 have an overall length that is about half the length of the conventional one, so that the entire apparatus is downsized to about half the size of the conventional one.

The pair of sensor tubes 8 and 9 are connected at their inflow-side ends 8a and 9a to the bellows 6 and 7, respectively.
The other ends 8b and 9b on the outflow side are connected to the inflow ports 10a and 10b of the outflow side manifold 10, respectively. The outflow pipe 11 is connected to the outflow port 10c of the outflow side manifold 10.
Are connected in communication.

Therefore, the pair of bellows 6, 7 and the pair of sensor tubes 8, 9 extend in parallel between the inflow side manifold 5 and the outflow side manifold 10. or,
Since the inflow side bellows 6 and 7 are formed in a bellows shape, they can be expanded and contracted in the axial direction (longitudinal direction), and when the sensor tubes 8 and 9 are vibrated, the end portions of the sensor tubes 8 and 9 are vibrated. It can also be bent in the radial direction (excitation direction) so as to allow displacement in the direction.

One ends 8a, 9 of the sensor tubes 8, 9
A vibrator 12 and a pickup 13 are arranged laterally between a. Therefore, the number of pickups is smaller than in the past.

The vibration exciter 12 has substantially the same structure as an electromagnetic solenoid in which an excitation coil 12a to which an excitation signal is input and a magnet 12b are opposed to each other, and the repulsive force generated between the excitation coil 12a and the magnet 12b or The suction force drives the one ends 8a and 9a of the sensor tubes 8 and 9 in a direction in which they are separated from each other or close to each other and vibrates.

The pickup 13 includes a sensor tube 7,
The detection coil 13a for outputting a detection signal corresponding to the amplitude of the ends 8a and 9a of the magnet 8 and the magnet 13b are opposed to each other. That is, the pickup 13 has the same structure as the electromagnetic solenoid, and outputs a voltage corresponding to the displacement of the sensor tubes 7 and 8 vibrated by the vibration exciter 12 as a detection signal.

When one ends 8a, 9a of the sensor tubes 8, 9 are vibrated by the vibrator 12, the sensor tubes 8,
9 is the other ends 8b and 9 fixed to the outflow side manifold 10.
Since b is a fulcrum and vibrates, the outflow side manifold 1
0 will function as a fixing member.

Since the vibrator 12 is provided at the ends 8a and 9a to which the elastically deformable bellows 6 and 7 are connected, the ends 8a and 9a of the sensor tubes 8 and 9 vibrate more than before. Can be made. Therefore, the amplitude of the ends 8a and 9a of the sensor tubes 8 and 9 at the time of flow rate measurement becomes large, and a larger Coriolis force is generated accordingly. As a result, the voltage value of the detection signal output from the pickup 13 becomes large, the measurement accuracy is further improved, and stable measurement can be performed even in a minute flow rate region where the Coriolis force is small.

Furthermore, since the voltage value of the detection signal output from the pickup 13 becomes large, it becomes less susceptible to the influence of disturbance, and for example, even if the pipe vibration propagates to the sensor tubes 8 and 9, the voltage of the detection signal of the pickup 13 is increased. Noise is smaller than the value, and measurement accuracy can be maintained.

When measuring the flow rate, the mass flowmeter 1 having the above configuration
In, the pair of sensor tubes 8 and 9 are vibrated by the vibration exciter 12 in the direction of approaching and separating (Y direction). The fluid to be measured supplied from the upstream pipe (not shown) is the inflow pipe 4
It further passes through the inflow side manifold 5, reaches the bellows 6, 7, and further flows into the vibrating sensor tubes 8, 9. The fluid that has passed through the sensor tubes 8 and 9 is
It flows out of the outflow pipe 11 through the flow path of the outflow side manifold 10 to a downstream side pipe (not shown).

In this way, the vibrating sensor tube 8,
When the fluid flows to 9, a Coriolis force having a magnitude corresponding to the flow rate is generated. Therefore, the Coriolis force Fc corresponding to the vibration direction of the vibrator 12 is generated in the straight sensor tubes 8 and 9 as shown by the arrow in FIG. Therefore,
The sensor tubes 8 and 9 will bend as shown by the broken line in FIG.

Therefore, one ends 8 of the sensor tubes 8 and 9 are
When a and 9a are vibrated in the Y direction by vibrating by the vibration exciter 12, the sensor tubes 8 and 9 as shown by broken lines in FIG.
Is displaced, the detection signal of the pickup 13 is detected later than the excitation signal to the vibrator 12. Therefore, a phase difference (time difference) depending on the magnitude of the Coriolis force Fc occurs between the excitation signal to the vibrator 12 and the detection signal of the pickup 13.

Therefore, as shown in FIG. 4, a phase difference occurs between the excitation signal input to the excitation coil 12a of the exciter 12 and the detection signal output from the pickup 13.
Since this phase difference is proportional to the flow rate, the flow rate measurement circuit 14
Calculates the flow rate based on the phase difference (time difference Δt) between the excitation signal input to the excitation coil 12a of the shaker 12 and the detection signal output from the pickup 13.

Moreover, when measuring the flow rate, the sensor tube 8,
When 9 is vibrated by the vibrator 12, the bellows 6 and 7 are elastically deformed not only in the axial direction but also in the radial direction, so that the ends 8a and 9a of the sensor tubes 8 and 9 have large amplitudes.
Moreover, the angular velocity is also large. Since a Coriolis force larger than that amount is generated in the sensor tubes 8 and 9, the detection signal of the pickup 13 and the excitation signal to the vibration exciter 12 are generated even though the total length of the sensor tubes 8 and 9 is only half of the conventional one. The phase difference of is large enough to measure the flow rate.

Therefore, when measuring the flow rate, the sensor tube 8,
Since the angular velocities of the one ends 8a and 9a of 9 become large, even when measuring the flow rate in the low flow rate range where the Coriolis force is small, the measurement can be performed accurately and the measurable range can be expanded. Further, since the measurement accuracy of the flow rate measurement can be improved by using the pickup 13 having the same structure as the electromagnetic solenoid as described above, it is not necessary to use an expensive high sensitivity sensor.

Here, the Coriolis force Fc can be expressed by the following equation.

Fc = −2 m (ω × v) (1) where m: mass of fluid and sensor tube ω: angular velocity normal to the longitudinal direction of the sensor tube due to vibration of the sensor tube v: fluid Velocity According to the above equation (1), when the velocity v of the fluid is constant, the angular velocity ω
Becomes larger, Coriolis force Fc becomes larger. Therefore,
Even if a disturbance occurs, the Coriolis force Fc is large and the influence is small. Also, even if there is a slight change in flow rate, Coriolis force F
Since c is large, the measurement accuracy is improved.

As shown in FIG. 5, the flow rate measuring circuit 14 is
Intrinsically safe explosion-proof barrier circuit 16 connected to sensor unit 15, excitation / time difference detection circuit 17, Young's modulus V
/ F conversion circuit 18, output circuit 19, and power supply circuit 20
And consists.

The intrinsically safe explosion-proof barrier circuit 16 includes each sensor of the sensor unit 15, that is, the excitation coil 1 of the vibrator 12.
2a, a detection coil 13a of the pickup 13, and a voltage / current limiting element (consisting of a Zener diode, a resistor, etc.) that makes the signals of the temperature sensor 21 intrinsically safe.

The excitation / time difference detection circuit 17 detects the displacement of the excitation circuit 22 that vibrates the sensor tubes 8 and 9 in a resonance state during flow rate measurement, and the displacement of the vibrating sensor tubes 8 and 9 as described later, and the excitation coil 12a and the time difference detection circuit 23 for detecting the time difference between the detection signal output from the detection coil 13a and the vibration system abnormality such as the imbalance of the vibrations of the sensor tubes 8 and 9 to stop the excitation. It comprises a safety circuit 24 for outputting an alarm and the like, and a time constant setting circuit 25 for setting a time constant.

The safety circuit 24 includes the sensor tube 8,
9 excessive vibration or the imbalance of the vibration of the two sensor tubes 8 and 9 is detected, and the abnormal vibration of the sensor tubes 8 and 9 is detected by the excitation system (excitation circuit 23) and the vibration detection system of the sensor tubes 8 and 9 ( It is monitored from both the time difference detection circuit 34).

The Young's modulus / V / F conversion circuit 18 amplifies the signal of the temperature sensor 21 to detect the temperature of the sensor tubes 8 and 9 which changes depending on the fluid temperature, and the Young's modulus to the temperature of the sensor tubes 8 and 9. The temperature detection circuit 26 that corrects the spring constant (Young's modulus) that is linked with the V and the V that converts the time difference signal (voltage value) corrected by the Young's modulus into a frequency signal.
The / F conversion circuit 27, a remote zero adjustment circuit 28 for calibrating the zero point by turning on a push button switch, and a display circuit 29 for monitoring the flow state and zero point drift with an LED (light emitting diode).

The output circuit 19 is the V / F conversion circuit 27.
A coefficient correction circuit 30 for converting the pulsed time difference signal into a unit mass pulse signal proportional to the time difference, and a frequency divider circuit 31 for converting the unit mass pulse signal output from the coefficient correction circuit 30 into a frequency of a certain divisor. And the frequency divider 31
A pulse output circuit 32 for amplifying the signal output from
An F / V conversion circuit 33 for converting the time difference signal pulsed by the V / F conversion circuit 27 into an analog signal (constant voltage or constant current signal) and a constant voltage output from the F / V conversion circuit 33. A constant current output circuit 34 that amplifies and outputs a constant current signal.

The normal flow rate measuring operation is performed by the excitation circuit 22 described above.
Then, a pulse having a constant cycle is output to the vibrator 12, and the sensor tubes 8 and 9 vibrate in a resonance state. Thus, when the fluid flows through the vibrating sensor tubes 8 and 9, Coriolis force of a magnitude proportional to the flow rate is generated. This causes a time difference between the excitation signal output from the excitation circuit 22 and the detection signal output from the detection coil 13a.

The time difference between the excitation signal and the detection signal is converted into a time difference signal by the time difference detection circuit 23,
Further, it becomes a flow rate pulse through the V / F conversion circuit 27, the coefficient correction circuit 30, the frequency dividing circuit 31, and the pulse output circuit 32.

The power supply circuit 30 is composed of a power supply transformer (not shown) configured to guarantee explosion-proof performance and a three-terminal regulator (not shown), and supplies a constant voltage to each of the above circuits.

Further, as shown by the alternate long and short dash line in FIG. 1, between the other ends 8b and 9b of the sensor tubes 8 and 9, there is provided a support plate 36 which is fixed so as to be laterally bridged between the sensor tubes 8 and 9. You may make it intervene. In this case, the support plate 36 serves as a fulcrum of vibration of the sensor tubes 8 and 9 and functions as a fixing member.

6 to 9 show a second embodiment of the present invention. In the drawings, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 6, a mass flowmeter 41 is formed by inserting a pipe line 42 through which a fluid to be measured passes in a closed casing 2. The pipe line 42 includes the inflow pipe 4 and the inflow side manifold 5.
The pair of inflow side bellows 6 and 7, the pair of sensor tubes 8 and 9, the pair of outflow side bellows 43 and 44, the outflow side manifold 10, and the outflow pipe 11.

A support plate 45 is fixed at an intermediate position in the longitudinal direction of the pair of sensor tubes 8 and 9 so as to be laterally bridged between the sensor tubes 8 and 9. Therefore, the sensor tubes 8 and 9 are fixed at the intermediate positions by the fixing of the support plate 45 and serve as fulcrums for vibration of the sensor tubes 8 and 9.

The pair of sensor tubes 8 and 9 have inflow-side ends 8a and 9a connected in communication with the inflow-side bellows 6 and 7, and outflow-side other ends 8b and 9b to outflow-side bellows 43 and 4.
4 is connected in communication. The outflow side bellows 4 is provided at the inflow ports 10a and 10b of the outflow side manifold 10.
The other ends of 3, 44 are connected for communication.

Since the outflow side bellows 43 and 44 are formed in a bellows shape like the inflow side bellows 6 and 7, they can be expanded and contracted in the axial direction (longitudinal direction) and the sensor tubes 8 and 9 are vibrated. In the radial direction (excitation direction) to allow displacement of the ends of the sensor tubes 8 and 9 in the excitation direction
It can also flex.

Therefore, both ends of the sensor tubes 8 and 9 are elastically deformable in the axial direction and the radial direction, and the inflow side bellows 6 is provided.
7. Since it is supported by the outflow side bellows 43 and 44, the one ends 8a and 9a and the other ends 8b and 9b are easily vibrated.

One ends 8a, 9 of the sensor tubes 8, 9
The agitator 12 and the pickup 13 are arranged laterally between a, and the agitator 46 and the pickup 47 are laterally arranged between the other ends 8b and 9b. There is.

Since the vibrator 46 has the same structure as the vibrator 12 described above, and the pickup 47 has the same structure as the pickup 13 described above, the description thereof will be omitted.

Therefore, the displacements of both ends of the sensor tubes 8 and 9 are detected by the pickups 13 and 47, and the pickups 13 and 47 respond to the displacements of the sensor tubes 7 and 8 excited by the exciters 12 and 46. Output voltage as a detection signal.

The inflow-side vibrator 12 is provided at one end 8a, 9a to which the elastically deformable bellows 6, 7 are connected, and the outflow-side vibrator 46 is elastically deformable.
Since 3, 44 are provided at the other ends 8b, 9b to which they are connected, both ends of the sensor tubes 8, 9 can be vibrated more than before. Therefore, the amplitude at both ends of the sensor tubes 8 and 9 at the time of flow rate measurement becomes large, and the angular velocity is also large. A Coriolis force larger than that amount is generated, and as a result, the voltage value of the detection signal output from the pickups 13, 47 becomes large.

Further, if the angular velocity of the sensor tubes 8 and 9 is increased and the Coriolis force is increased, even if a disturbance occurs, the Coriolis force Fc is large and the influence is small.
Further, even if there is a slight change in the flow rate, the Coriolis force Fc is large, so the measurement accuracy is improved.

Further, the ends 8a, 9 of the sensor tubes 8, 9 are
Since the angular velocities of a and the other ends 8b and 9b are increased, accurate measurement can be performed even when measuring a flow rate in a low flow rate range where Coriolis force is small, and the measurable range can be expanded. Moreover, since the measurement accuracy of the flow rate measurement can be improved by using the pickup 13 having the same structure as the electromagnetic solenoid as described above, it is not necessary to use an expensive and highly sensitive sensor.

When measuring the flow rate, the mass flowmeter 1 having the above configuration.
At both ends of the pair of sensor tubes 8 and 9 are alternately approached and separated by the vibrators 12 and 46 (Y direction).
Be vibrated. That is, the sensor tubes 8 and 9 have the other ends 8a and 9a when the other ends 8a and 9a are driven toward each other.
b and 9b are driven in the direction away from each other. Also, one end 8
When a and 9a are driven in the direction away from each other, the other end 8
b and 9b are driven toward each other.

The fluid to be measured supplied from the upstream pipe (not shown) reaches the bellows 6, 7 from the inflow pipe 4 through the inflow manifold 5, and flows into the vibrating sensor tubes 8, 9. . Then, the fluid that has passed through the sensor tubes 8 and 9 flows out from the outflow pipe 11 to a downstream side pipe (not shown) through the flow passages of the bellows 43 and 44 and the outflow side manifold 10.

In this way, the vibrating sensor tube 8,
When the fluid flows to 9, a Coriolis force having a magnitude corresponding to the flow rate is generated. Therefore, the Coriolis force Fc corresponding to the vibration direction of the vibration exciter 12 is generated in the straight sensor tubes 8 and 9 as shown by the arrow in FIG. Further, when the vibrating state is enlarged, the sensor tubes 8 and 9 are as shown in FIG. 8. The sensor tubes 8 and 9 vibrate with a larger amplitude as the distance from the support plate 45 increases, and the angular velocity increases as the distance from the support plate 45 increases. growing. Therefore, the sensor tube 8,
9, both ends will bend as shown by the broken line in FIG.

In this way, the vibrating sensor tube 8,
When the fluid flows to 9, a Coriolis force having a magnitude corresponding to the flow rate is generated. Therefore, an operation delay occurs between the inflow side and the outflow side of the straight tube-shaped sensor tubes 7 and 8, so that a phase difference appears in the output signals of the pickups 13 and 47.

Since this phase difference is proportional to the flow rate, the flow rate measuring circuit 48 calculates the flow rate based on the phase difference between the output signals from the pickups 13 and 47.

Further, in the present embodiment, as described above, when the one ends 8a, 9a of the sensor tubes 8, 9 are driven in the approaching direction to each other, the other ends 8b, 9b are driven in the separating direction from each other. Excitation coils 12a, 4 of the shakers 12, 46
Reverse the polarity (+,-) of 6a, or shaker 1
2, 46 magnets 12b, 46b polarities (N pole, S
By reversing the poles, it is possible to output an excitation signal from the same excitation circuit of the flow rate measurement circuit 48 to the excitation coils of the exciters 12 and 46. As a result, as the circuit configuration of the flow rate measuring circuit 48, the known circuit configuration can be used as it is.

FIG. 10 shows a third embodiment of the present invention. still,
In each figure, the same parts as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, the mass flowmeter 51 is the above-mentioned second
This is a modified example of the embodiment, and the interval between the pair of sensor tubes 8 and 9 is formed to have different sizes in three steps. The separation distance between the sensor tubes 8 and 9 is determined by the inflow-side ends 8a and 9 where the vibrator 12 and the pickup 13 are arranged.
The distance is La at a, the distance is Lb at the intermediate positions 8c and 9c to which the support plate 45 is fixed, and the distance L is at the other ends 8b and 9b on the outflow side where the vibrator 46 and the pickup 47 are arranged.
c.

Since the separation distance between the sensor tubes 8 and 9 at each position is La <Lb <Lc, the distance gradually increases toward the outflow side. Also, one end 8a, 9
Between a and the intermediate positions 8c and 9c, the distances from La to Lb
Bent portions 8d and 9d that are bent so as to incline are interposed, and between the intermediate positions 8c and 9c and the other ends 8b and 9b,
Bent portion 8 bent so as to incline from the interval Lb to Lc
e and 9e are interposed.

As described above, the sensor tubes 8 and 9 are bent at the intermediate positions 8c and 9c at the upstream and downstream sides of the bent portions 8d, 9d and 8 respectively.
e and 9e are interposed to facilitate bending, the ends 8a and 9a and the other end 8 which are vibrated by the vibrators 12 and 46.
b and 9b easily vibrate in the radial direction (Y direction). Therefore, when measuring the flow rate, one end 8a, 9a and the other end 8
When b and 9b are vibrated, one end 8a, 9a and the other end 8
The amplitudes of b and 9b are increased, and the pickups 13 and 47 are
Makes it easy to detect the Coriolis force proportional to the flow rate.

Since the voltage value of the detection signal output from the pickups 13 and 47 is correspondingly increased, it is less likely to be affected by disturbance, and, for example, pipe vibration is caused by the sensor tube 8.
Even if it propagates to 9, noise is smaller than the voltage values of the detection signals of the pickups 13 and 47, and the measurement accuracy can be maintained.

Further, in the sensor tubes 8 and 9, the inflow-side ends 8a and 9a are connected to the elastically deformable bellows 6 and 7, and the outflow-side other end 8 is the same as in the second embodiment.
Since b and 9b are connected to the elastically deformable bellows 43 and 44, one end 8a, 9a and the other end 8b, 9b can vibrate more than before. Therefore, the amplitude of one end 8a, 9a and the other end 8b, 9b at the time of flow rate measurement becomes large, and the angular velocity is also large. Coriolis force larger than that amount is generated, and as a result, the pickups 13, 47 are
The voltage value of the detection signal output from is increased.

Further, when the angular velocity of the sensor tubes 8 and 9 increases and the Coriolis force increases, even if a disturbance occurs, the Coriolis force Fc is large and the influence is small.
Further, even if there is a slight change in the flow rate, the Coriolis force Fc is large, so the measurement accuracy is improved.

The ends 8a, 9 of the sensor tubes 8, 9 are also
Since the angular velocities of a and the other ends 8b and 9b are increased, accurate measurement can be performed even when measuring a flow rate in a low flow rate range where Coriolis force is small, and the measurable range can be expanded. Moreover, since the measurement accuracy of the flow rate measurement can be improved by using the pickup 13 having the same structure as the electromagnetic solenoid as described above, it is not necessary to use an expensive and highly sensitive sensor.

11 and 12 show a fourth embodiment of the present invention.

In both figures, the mass flow meter 61 has a sealed casing 62 in which a pair of sensor tubes 63, 64 through which the fluid to be measured passes are housed. Sensor tube 6
Reference numerals 3 and 64 are curved in an inverted U-shape, and extend in the up-down direction (Y direction) and are parallel to the inflow-side straight pipe portions 63a and 64a and the inflow-side straight pipe portions 63a and 64a. direction)
The straight pipe portions 63b and 64b extend to the bottom, and the curved portions 63c and 64c are curved between the straight pipe portions 63a and 64a and the straight pipe portions 63b and 64b.

Lower ends 63 of the inflow side straight pipe portions 63a and 64a
Inflow side bellows 65 and 66 are connected to d and 64d,
Outflow side bellows 67 and 68 are connected to lower ends 63e and 64e of the outflow side straight pipe portions 63b and 64b.

Further, at the intermediate position between the curved portions 63c and 64c,
A support plate 69 fixedly provided so as to horizontally extend between the sensor tubes 63 and 64 is provided. Therefore, the sensor tubes 63 and 64 are fixed at the intermediate positions by the fixing of the support plate 69 and serve as fulcrums for vibration of the sensor tubes 63 and 64.

Reference numeral 70 denotes a manifold, and the inflow passage 7 is provided at one end.
0a is bored in the longitudinal direction, and an outflow passage 70b is bored in the longitudinal direction at the other end. Further, a connection hole 70c extending in the orthogonal radial direction is bored in the inner part of the inflow passage 70a, and a connection hole 70d extending in the orthogonal radial direction is also bored in the inner part of the outflow passage 70b. ing.

Therefore, the inflow side bellows 65 and 66 are fixed in a state of being inserted into the connection hole 70c of the manifold 70, and the outflow side bellows 67 and 68 are fixed to the manifold 70.
It is fixed in a state of being inserted in the connection hole 70d.

Since each of the bellows 65 to 68 is formed in a bellows shape, it can be expanded and contracted in the axial direction (longitudinal direction), and at the both ends of the sensor tubes 63 and 64 when the sensor tubes 63 and 64 are vibrated. Some lower ends 63d, 64d
It is also possible to bend in the radial direction (excitation direction) so as to allow the displacement of 63e and 64e in the excitation direction.

Between the lower ends 63d and 64d on the inflow side of the sensor tubes 63 and 64, a vibrator 71 and a pickup 72 are disposed so as to horizontally extend, and the lower end 63 on the outflow side is arranged.
A vibration exciter 73 and a pickup 74 are arranged laterally between e and 64e.

Therefore, the displacements of both ends of the sensor tubes 63 and 64 are detected by the pickups 72 and 74, and the pickups 72 and 74 are the lower ends 63d of the sensor tubes 63 and 64 vibrated by the vibrators 71 and 73, respectively. 64
The voltage corresponding to the displacement of d and 63e, 64e is output as a detection signal.

The vibrator 71 on the inflow side has lower ends 63d and 64d to which elastically deformable bellows 65 and 66 are connected.
Since the vibrator 73 on the outflow side is provided on the lower ends 63e and 64e to which the elastically deformable bellows 67 and 68 are connected, the sensor tube without the bellows 65 and 66 is formed into an inverted U shape. Both ends of the sensor tubes 63 and 64 can be vibrated more than the conventional device which is just bent. Therefore, the sensor tube 6 when measuring the flow rate
The amplitude at both ends of 3, 64 is large, and the angular velocity is also large. Coriolis force larger than that is generated, and as a result,
The voltage value of the detection signal output from the pickups 72 and 74 increases.

Since the voltage value of the detection signal output from the pickups 72 and 74 is increased in this way, it is less likely to be affected by disturbance, and for example, even if pipe vibration propagates to the sensor tubes 63 and 64, the pickups 72 and 74 are picked up. Noise is smaller than the voltage value of the detection signal of, and measurement accuracy can be maintained.

Further, since the angular velocities at both ends (lower ends 63d, 64d and 63e, 64e) of the sensor tubes 63, 64 become large, accurate measurement can be performed even when measuring the flow rate in the low flow rate range where the Coriolis force is small. Yes, the measurable range can be expanded. Moreover, the pickups 72, 74 having the same structure as the electromagnetic solenoid as described above are used.
Since the measurement accuracy of the flow rate measurement can be improved by using, it is not necessary to use an expensive and highly sensitive sensor.

When measuring the flow rate, the mass flowmeter 6 having the above-mentioned configuration
1, the both ends of the pair of sensor tubes 63 and 64 are moved closer to and away from the vibrators 71 and 73 (X direction).
Be vibrated.

The fluid to be measured supplied from the upstream side pipe (not shown) vibrates from the inflow passage 70a of the manifold 70 through the inflow side bellows 65, 66 and vibrates.
It flows into 3,64. Then, the sensor tube 63,
64 inflow side straight pipe portions 63a, 64a, curved portions 63c, 64
c, the fluid that has passed through the outflow side straight pipe portions 63b and 64b flows out to the downstream side pipe (not shown) through the outflow side bellows 67 and 68 and the outflow passage 70b of the manifold 70.

The sensor tube 6 vibrating in this way
When the fluid flows through the channels 3, 64, Coriolis force having a magnitude corresponding to the flow rate is generated. Therefore, the sensor tube 6
Coriolis force F corresponding to the vibration direction is applied to the inflow side straight pipe portions 63a, 64a and the outflow side straight pipe portions 63b, 64b of 3, 64.
c is generated.

Further, since the sensor tubes 63 and 64 vibrate in the X direction with the support plate 69 as a fulcrum, the sensor tubes 63 and 64 vibrate with a larger amplitude as the distance from the support plate 69 increases, and the angular velocity also increases as the distance from the support plate 69 increases. growing.

Further, the sensor tubes 63 and 64 are U-shaped.
Since the intermediate position of the curved portions 63c and 64c is fixed by the support plate 69, the inflow side straight pipe portions 63a and 64a and the outflow side straight pipe portions 63b and 64b are formed by the vibrators 71 and 73.
Is vibrated in the X direction, the curved portions 63c and 64c are twisted, and the inflow side straight pipe portions 63a and 64a and the outflow side straight pipe portion 63 are
The lower ends 63d and 64d and 63e and 64e of b and 64b easily vibrate in the X direction. Therefore, when the lower ends 63d, 64d and 63e, 64e are vibrated during the flow rate measurement, the amplitude of the lower ends 63d, 64d and 63e, 64e becomes large, and the Coriolis force proportional to the flow rate can be easily detected by the pickups 72, 74.

The sensor tube 6 vibrating in this way
When the fluid flows through the channels 3, 64, Coriolis force having a magnitude corresponding to the flow rate is generated. Therefore, the inflow side straight pipe portion 63
a and 64a and the outflow side straight pipe portions 63b and 64b cause operation delays, which causes a phase difference in the output signals of the pickups 72 and 74.

Since this phase difference is proportional to the flow rate, a flow rate measuring circuit (not shown) calculates the flow rate based on the phase difference between the output signals from the pickups 72 and 74.

In each of the above embodiments, the structure in which the bellows is connected to the end portion of the sensor tube has been described as an example. However, instead of the bellows, for example, a pipe line may be formed in an α shape or an Ω shape so as to be elastically deformable. It may be curved or a flexible metal tube may be used.

[0092]

As described above, according to the first aspect, one end of the sensor tube connected to the flexible conduit is vibrated by the vibrator, and the displacement of the one end of the sensor tube is detected by the pickup. Therefore, the elastic deformation of the flexible pipe can increase the amplitude of one end of the sensor tube and increase the angular velocity. A Coriolis force larger than that amount is generated in the sensor tube, and even if a disturbance occurs, the Coriolis force is large and the influence of the disturbance is small.
Further, since the Coriolis force is large even if there is a minute change in flow rate, the measurement accuracy is improved and stable measurement can be performed even in a minute flow rate range where the Coriolis force is small. As a result, it is possible to use an inexpensive pickup with relatively low detection performance, which reduces manufacturing costs, and even if the total length of the sensor tube is shortened, the displacement of one end of the sensor tube can be measured. This can be ensured, and the device can be downsized.

According to the above-mentioned claim 2, both ends of the sensor tube connected to the flexible tube are excited by the vibrator, and the displacement of both ends of the sensor tube is detected by the pickup. The elastic deformation of the path increases the amplitude at both ends of the sensor tube and also increases the angular velocity. A Coriolis force larger than that amount is generated in the sensor tube, and even if a disturbance occurs, the Coriolis force is large and the influence of the disturbance is small. Further, since the Coriolis force is large even if there is a minute change in flow rate, the measurement accuracy is improved and stable measurement can be performed even in a minute flow rate range where the Coriolis force is small. This makes it possible to use an inexpensive pickup having a relatively low detection performance and reduce the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a mass flow meter as a first embodiment of a vibration type measuring device according to the present invention.

FIG. 2 is a diagram for explaining a Coriolis force generated by a measurement operation of the vibration measuring device shown in FIG.

FIG. 3 is a diagram showing displacement of a sensor tube due to Coriolis force.

FIG. 4 is a waveform diagram showing a time difference between an excitation signal and a detection signal.

FIG. 5 is a block diagram of a flow rate measuring circuit.

FIG. 6 is a vertical sectional view of a second embodiment of the present invention.

7 is a diagram for explaining a Coriolis force generated by the measurement operation of the vibration measuring device shown in FIG.

FIG. 8 is a graph showing the magnitude of Coriolis force in the longitudinal direction of the sensor tube.

FIG. 9 is a diagram showing displacement of a sensor tube due to Coriolis force.

FIG. 10 is a vertical sectional view of a third embodiment of the present invention.

FIG. 11 is a front view in which only a casing according to a fourth embodiment of the present invention is sectioned.

FIG. 12 is a side view in which only the casing of the fourth embodiment of the present invention is sectioned.

[Explanation of symbols]

 1,41,51,61 Mass flowmeter 2,62 Casing 4 Inflow pipe 5 Inflow side manifold 6,7 Bellows 8,9,63,64 Sensor tube 10 Outflow side manifold 11 Outflow pipe 12,71,73 Vibrator 13 , 47, 72, 74 Pickup 14, 46 Flow rate measuring circuit 45, 69 Support plate 65, 66 Inflow side bellows 67, 68 Outflow side bellows 70 Manifold

Claims (2)

[Claims] 1. A sensor tube through which a fluid to be measured flows, and a flexible conduit which is connected to one end of the sensor tube and supports one end of the sensor tube so as to allow radial displacement of the sensor tube. A fixing member that fixedly supports the other end of the sensor tube, a vibration exciter that vibrates and vibrates one end of the sensor tube, and a pickup that detects displacement of one end of the sensor tube due to generation of Coriolis force. A vibration-type measuring device comprising: 2. A sensor tube through which a fluid to be measured flows, a flexible conduit which is connected to both ends of the sensor tube and supports the sensor tube so as to allow radial displacement of the sensor tube, A fixing member for fixedly supporting an intermediate position of the sensor tube, a vibrator for exciting and vibrating both ends of the sensor tube, and a pickup for detecting displacement of both ends of the sensor tube due to generation of Coriolis force, A vibration-type measuring device comprising: