JPH04204328A - Mass flow meter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 monitor abnormalities in a sensor tube through which a fluid to be measured flows.

2. Description of the Related Art As one type of mass flowmeter that directly measures the mass flow rate of a fluid to be measured, there is a flowmeter that measures the mass flow rate using the Coriolis force that is generated when a fluid flows through a vibrating sensor tube.

In this type of mass flowmeter, fluid is caused to flow through a pair of sensor tubes, and the pair of sensor tubes are vibrated toward and away from each other by the driving force of a vibrator (a 10-magnetic coil). Coriolis force acts in the direction of vibration of the sensor tube, and since the inlet and outlet sides are in opposite directions, the sensor tube is twisted, and this twist angle is proportional to the mass flow rate. Therefore, a pickup (vibration sensor) for detecting vibration is installed at the twisting position on the inlet side and outlet side of a pair of sensor tubes, and the time difference between the output detection signals of both sensors is measured. Measuring flow rate.

Further, in the mass flowmeter having the above structure, a box-shaped cover is provided to protect the sensor tube, pickup, vibrator, etc.

Problem to be Solved by the Invention Since the mass flowmeter described above vibrates the sensor tube in a resonant state, if used for a long period of time, stress will be applied to the root or welded part of the sensor tube, causing cracks in the sensor tube. There is a thing. In that case, the fluid in the sensor tube flows into the cover and the vibration of the sensor tube becomes unstable.

However, since the sensor tube is housed inside the cover, it is impossible to check it from the outside, so conventionally, the occurrence of an abnormality has been detected by monitoring the resonance state of the sensor tube.

However, if air bubbles mixed into the fluid accumulate in the sensor tube, the resonance state of the sensor tube will change, so it can be determined whether there is a crack in the sensor tube or whether gas has accumulated in the sensor tube. I couldn't come. Therefore, even if a mass flow meter detects an abnormal vibration in the sensor tube, it is impossible for the operator to remove the cover and check the cause of the problem, resulting in delays in taking action when an abnormality occurs, or taking appropriate countermeasures. There were some issues such as not being taken into consideration.

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 houses a sensor tube through which a fluid to be measured flows in a sealed housing, vibrates the sensor tube, and prevents the displacement of the sensor tube due to Coriolis caused by the vibration. A mass flow meter that measures the flow rate of a fluid to be measured by detecting it with a displacement detection means, a strain gauge that detects the degree of deflection of the casing, and a vibration abnormality of the sensor tube based on a detection signal of the displacement detection means. vibration abnormality detection means for detecting an abnormality; a determination means for determining whether or not the sensor tube is damaged based on an abnormality detection signal from the vibration abnormality detection means and a detection signal from the strain gauge; and abnormality occurrence processing means for performing processing after the occurrence of the abnormality when it is determined that the abnormality has occurred.

Further, in the above mass flowmeter, the following steps are provided: a humidity sensor that detects humidity inside the housing; a vibration abnormality detection means that detects abnormality in vibration of the sensor tube based on a detection signal of the displacement detection means; a determination means for determining whether or not the sensor tube is damaged based on an abnormality detection signal from the sensor and a detection signal from the humidity sensor; and an abnormality occurrence process for performing post-abnormality processing when the determination means determines that an abnormality has occurred. It will be equipped with the means.

Further, in the above mass flowmeter, the following elements are provided: a pressure sensor that detects the pressure inside the housing; a vibration abnormality detection means that detects abnormality in vibration of the sensor tube based on a detection signal of the displacement detection means; determination means for determining whether or not the sensor tube is damaged based on the abnormality detection signal from the sensor and the detection signal from the pressure sensor; and an abnormality occurrence process for performing post-abnormality processing when the determination means determines that an abnormality has occurred. It will be equipped with the means.

The output signal of the displacement detection means that detects the displacement of the sensor tube is used to monitor whether abnormality in vibration of the sensor tube is detected, and the degree of deflection of the housing is detected using a strain gauge to detect fluid leaking from the sensor tube. Monitor to see if it has accumulated inside the casing. When an abnormality is detected by both monitoring, the determination means determines that an abnormality has occurred, and at the same time, the abnormality occurrence processing means performs post-processing such as reporting that there is an abnormality in the sensor tube.

Further, when detecting an abnormality in the vibration of the sensor tube and detecting fluid leaking from the sensor tube or the humidity sensor that detects the humidity inside the housing, the determination means determines that an abnormality has occurred, and at the same time, the abnormality processing means or sensor tube Post-processing such as notifying the user that there is an abnormality is performed.

In addition, when a pressure sensor detects an abnormality in the vibration of the sensor tube and detects the pressure inside the housing, or an increase in pressure inside the housing is detected due to fluid leaking from the sensor tube,
The determination means determines that an abnormality has occurred, and at the same time, the abnormality occurrence processing means performs processing such as reporting that there is an abnormality in the sensor tube.

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

In both figures, a mass flowmeter 1 is installed along with a pump 3 and a main valve 4 in the middle of a pipe 2, and a pair of flowmeters in which the fluid to be measured flows inside a cover (casing) IA with a box-like sealed structure. It houses sensor tubes 5 and 6.

This mass flowmeter 1 is a Coriolis type flowmeter that measures the flow rate by detecting the displacement of the sensor tubes 5 and 6 due to Coriolis that occurs when fluid flows through a pair of sensor tubes 5 and 6 that vibrate in a resonant state. . Therefore, the sensor tubes 5 and 6 are protected from dew condensation, dust, external force, etc. by the cover IA.

The sensor tubes 5 and 6 are bent in a U-shape in a side view and in a 3-shape in a plan view, and are attached symmetrically to the tube 7.

Reference numeral 8.9 denotes a vibrator, which vibrates each sensor tube 56 in the direction of arrow X by the self-excited oscillation circuit 13.

10.11 is a pickup, sensor tube 5,
The vibration in the direction of arrow X of 6 is detected.

The fluid supplied through the upstream piping (not shown) branches within the mass flow meter 1 as indicated by the arrow ■ and flows within the sensor tubes 5 and 6 as indicated by the arrow ■, respectively. They are merged together as shown by the arrow mark and enter the pipe 7, and flow within the pipe 7 as shown by the arrow ■ to reach the downstream piping.

When the fluid flows through the vibrating sensor tubes 5 and 6, a Coriolis force is generated, which causes the sensor tube 5 to
, 6 causes a time difference in the vibrations.

Sensor tube 5.6 Vibration or pickup 10.11
The time difference of this vibration is converted into a voltage by the time difference-voltage conversion circuit 20, and further converted into a frequency by the V-F conversion circuit 21, and then the time difference of this vibration is converted into a voltage by the V-F conversion circuit 21, and then the time difference of this vibration is converted into a voltage by the V-F conversion circuit 21.
2, the flow rate signal is sent from the terminal 22a to the control circuit 2, which will be described later.
3 is output.

The circuits 21 and 22 constitute the processing circuit 24.

Reference numeral 30 denotes an integrating circuit, which converts a voltage signal (speed voltage signal) corresponding to the vibration speed of the sensor tube 5 from the negative pickup 1O into a voltage signal (amplitude voltage signal) corresponding to the amplitude of the sensor tube 5.

Reference numeral 31 is an amplitude monitoring circuit for monitoring abnormality in vibration of the sensor tube 5 as a vibration abnormality detection means, and a rectifier circuit 32 for rectifying the eight components of the integrating circuit 30 and a reference voltage V1. ．．
The reference voltage generation circuit 33 and the comparison circuit 34 output the voltage.

The comparison circuit 34 compares the output voltage V of the rectifier circuit 32 with the circuit 33.
Reference voltage ■7. ．． Compare V≦V1. , an amplitude abnormality signal a is output as an abnormality detection signal.

Reference numeral 35 denotes a sample and hold circuit, which is provided between the time difference-voltage conversion circuit 20 and the V-F conversion circuit 21.

This circuit 35 consists of, for example, an FET, etc., and includes a normally closed electronic switch 36 that is opened when the amplitude abnormality signal a is received, and a capacitor of a predetermined capacity C connected in parallel to the next stage of this electronic switch 36. 37, and an amplifier 38 at the next stage of the capacitor 37.

When the electronic switch 36 is opened, the capacitor 37 maintains its previously charged charge and the electronic switch 3
6. The output voltage of the circuit 20 at the time immediately before the circuit 20 is opened is sampled and held.

Here, the operation of the above configuration will be explained.

When the flow rate measurement is normal, the output voltage V of the circuit 32 in Fig. 1 is large, and there is a relationship of V>V,, r (v, + l;! reference voltage), and the abnormal amplitude signal a is not output. , the electronic switch 36 is closed.

Therefore, the output voltage V of the circuit 20 passes through the circuit 35 as it is, becomes the output voltage V2 of the circuit 35, and is applied to the circuit 21 (processing circuit 24).

Furthermore, the flow rate signal is outputted from the terminal 22a via the next stage circuit 22.

At this point, suppose that as flow rate measurement progresses, air bubbles enter the sensor tube S and the signal from the sensor tube 5 suddenly becomes disturbed.

When the vibration of the sensor tube 5 is disturbed, the output voltage (1) of the circuit 20 fluctuates abnormally.

Further, when the vibration of the sensor tube 5 is disturbed, the resonance state with the sensor tube 6 is broken and the amplitude becomes small, so that the voltage V of the circuit 32 decreases, and the reference voltage V7. ．．
Below, V≦V7. , and the circuit 31 (34) outputs the amplitude abnormality signal a.

When this signal a is output, the electronic switch 36 is opened, the sample and hold circuit 35 is operated, and the voltage is held at the voltage (2) immediately before the electronic switch 36 is opened.

From then on, the voltage V or the corresponding flow rate signal is transmitted to the control circuit 2.
3 is output.

It is assumed that after a predetermined period of time has elapsed, the bubbles are removed from the sensor tube 5 and the disturbance in the vibration of the sensor tube 5 is restored.

When the abnormal vibration of the sensor tube 5 subsides, the output voltage V of the circuit 32 in FIG. 1 recovers and increases, and V > V y
@ becomes L, and the output of signal a disappears.

As a result, the electronic switch 36 is closed and the previous normal flow rate measurement state is restored, and the output voltage V of the circuit 20 becomes the output voltage V2 of the next stage circuit 35 and is applied to the next stage processing circuit 24. Added. That is, a flow rate signal based on the output voltage v1 of the circuit 20 is output.

After that, even if a bubble enters the sensor tube 5, the output voltage of the circuit 20 at the time immediately before the vibration or abnormality of the sensor tube 5 is sampled and held in the period where the vibration of the sensor tube 5 is abnormal. A flow signal is output based on this output voltage, and when the abnormal vibration subsides,
Again, the output voltage of the circuit 20 is directly applied to the circuit 24, and a flow rate signal is generated based on the output voltage of the circuit 20.

Next, the main parts of the present invention will be explained.

A pair of sensor tubes 5.6 pass through the support plate 17 and are fixed to the support plate 17 by brazing or welding. Therefore, the sensor tube 5.6 vibrated by the vibrators 8 and 9 vibrates in the X direction from the distal end side using the joint portion with the support plate 17 as a fulcrum.

When flow rate measurement is performed for a long period of time, metal fatigue is likely to occur in the vibrating sensor tube 5, 6 as described above. In particular, stress tends to concentrate on the portions of the sensor tubes 5, 6 fixed to the support plate 17, which may cause cracks in the sensor tubes 5, 6. In that case, sensor tube 5.6
The resonant frequency of the device will deviate from normal, causing abnormal vibrations similar to those caused when air bubbles are mixed in.

Therefore, the control circuit 23 is inputted with a program as a determining means for determining whether or not the sensor tubes 5 and 6 are damaged, such as the above-mentioned cracks, and as an abnormality occurrence processing means for performing processing after the occurrence of an abnormality. Also, both sides IA, , IA of cover IA
1st and 2nd strain gauges 14 and 15 are attached to the inner wall of 2. This strain gauge 14.15 is located on the side surface IA of the cover IA.

It has a characteristic that the resistance value changes when the cover I is deformed, and outputs a signal to the control circuit 23 according to the deformation state of the cover I.

Also, the control circuit 23 receives the amplitude abnormality signal a from the amplitude monitoring circuit 31 from the V-F conversion circuit 21, or whether the amplitude abnormality signal a alone indicates that air bubbles have accumulated in the sensor tubes 5 and 6. Since it is not possible to determine whether the problem is caused by a bamboo shoot or if the sensor tubes 5 and 6 are damaged, the occurrence of an abnormality is monitored using the signals from the pair of strain gauges 14 and 15, as will be described later.

16 is a display unit that displays the mass flow rate and also controls the control circuit 2.
When the content of the abnormality occurrence is determined in step 3, the situation is displayed and notified to the operator.

Here, the processing executed by the control circuit 23 will be explained with reference to FIG.

First, the control circuit 23 reads a signal from the amplitude monitoring circuit 31 in step S1 (hereinafter the step will be omitted) in FIG. In the next step 82, it is checked whether the signal read in Sl or the abnormal amplitude signal a is detected.

If it is determined in S2 that the amplitude abnormal signal a is not output, the process moves to S3 and the output of the first strain gauge 14 is read. In the next 84, strain gauge 1 read in S3
If the output of the second strain gauge 15 is normal, that is, there is no distortion or if it is within the allowable range, the process moves to S5, and the second strain gauge 15 is output.
Read the output of .

In S6, if the output of the strain gauge 15 read in S5 is also normal, there is no abnormality, and the process returns to S1.

However, in S4 or S6, the strain gauge 14
．． 15, if the distortion exceeds the allowable range and an abnormality is detected, the process moves to S8, and the display 16 displays "Cover external deformation".
is displayed to notify the operator. This is the amplitude monitoring circuit 3
If only one of the strain gauges is detected to be abnormal even though the signal 1 is normal, this is because it is determined that some external force has acted on the cover IA and a portion of the cover IA has been deformed.

In this case, the operator should check the extent of the damage to the cover IA,
If the damage is severe, replace the cover IA.

Also, when the amplitude abnormal signal a is detected in S2,
Proceeding to S9, the output of the first strain gauge 14 is read. In the next SIO, if the output of the strain gauge 14 read in S9 is normal, the process moves to 311 to read the output of the second strain gauge 15.

In S12, if the output of the strain gauge 15 read by Sll is normal, the process moves to S13 and displays "Bubbles present" on the display section 16 to notify the operator. This is because if there is no abnormality in the strain gauges 14 and 15 but only the frequency, it is determined that air bubbles have accumulated in the sensor tubes 5 and 6 and the resonance frequency has changed. In this case, the operator bleeds the air inside the sensor tube 5.6 if necessary.

Further, when an abnormality is detected in the strain gauge 14 in the SIO, the process moves to S14 and the output of the second strain gauge 15 is read.

In the next S15, if the output of the strain gauge 15 read in S14 is normal, the process moves to 316 and displays "Suspected tube damage" on the display section 16 to notify the operator. This is the frequency of the sensor tubes 5 and 6 and one strain gauge 14.
In this case, there is a possibility that air bubbles accumulate in the sensor tubes 5 and 6 and the cover deforms due to an external force at the same time, so the tubes may be damaged. This is because it is determined that the strain gauge 15 is stiff.In addition, if an abnormality is detected in the strain gauge 15 in S12, the process moves to S16, and the display unit 16 displays "Suspected tube breakage." In this case, the operator removes the cover IA and checks the sensor tubes 5 and 6 for damage.

If an abnormality is detected in the second strain gauge 15 in S15, it means that there is an abnormality, and the process moves to S17, where "Tube breakage has occurred" is displayed. This is because it was determined that at the same time as abnormal vibrations occurred due to tube breakage, fluid leaked from the tube 5.6 accumulated in the cover IA and the cover IA was deformed by the pressure and weight of the fluid. In this case, the operator immediately closes the main valve 4 and replaces it with a new mass flowmeter.

In this way, the control circuit 12 grasps the nature of the abnormality that has occurred in the mass flowmeter 1 based on a combination of the change in the vibration frequency of the sensor tube 56 and the change in the resistance value of the pair of strain gauges 14 and 15, and notifies it through the display unit 16. I can do it. Therefore, the operator can confirm the details of the abnormality, and for example, can he or she mistakenly believe that there is air bubbles or accumulation inside the sensor tubes 5 and 6 even though the sensor tubes 5 and 6 are damaged? Prevented. Therefore, the operator can detect an abnormality and immediately take countermeasures according to the details of the abnormality, thereby preventing the damage from increasing due to delays in taking countermeasures.

In the above description, it is assumed that the operator closes the main valve 4 after 317, but is not limited to this, and after the process of S17,
The control circuit 23 may drive the main valve 4 to close, or the pump 3 may be automatically stopped.

A second embodiment of the present invention is shown in FIGS. 3 and 4.

In FIG. 3, the same components as those in FIG.

Both sides of force/<-IA IA1. A humidity sensor 18. is installed on the inner wall of IA2. A pressure sensor 19 is attached. The humidity sensor 18 is a sensor that detects a change in moisture in the air within the cover IA, that is, the humidity within the cover IA, and includes, for example, a polymer film humidity sensor, a ceramic humidity sensor, a dew condensation sensor, or the like. Further, the pressure sensor 19 detects the pressure inside the cover IA, and outputs a detection signal when fluid leaks from the sensor tubes 5 and 6 and a pressure rise occurs.

The humidity sensor 18 and the pressure sensor 19 are connected to the control circuit 23 and output detection signals to the control circuit 23, respectively. still,
The inside of cover I is usually inert gas (e.g. N2 gas)
The container is kept dry and at a constant pressure. Therefore, unless there is some abnormality, the humidity and pressure inside the cover IA are almost constant.

Here, the abnormality processing executed by the control circuit 23 shown in FIG. 3 will be explained with reference to FIG. 4.

First, the control circuit 23 reads a signal from the amplitude monitoring circuit 31 in step 521 (hereinafter the step will be omitted) in FIG. In the next step 822, it is checked whether the signal read in S21 is the abnormal amplitude signal a.

If it is determined in S22 that the amplitude abnormal signal a is not output, the process moves to S23 and the output of the humidity sensor 18 is read. In the next step 324, if the pressure of the humidity sensor 18 read in S23 is normal, that is, the humidity is within a predetermined range, the process moves to 825 and the pressure of the pressure sensor 19 is read.

In the next step 326, the pressure sensor 1 read in S25
If the output of 9 is normal within a predetermined range, there is no abnormality and the process returns to 321. However, in S26, when the pressure sensor 19 detects a pressure increase, the process moves to S28 and displays "temperature rise" on the display section 16. This is caused by pressure sensor 1 even though amplitude monitoring circuit 31 and humidity sensor 18 are normal.
Since only No. 9 was detected as abnormal, it was determined that the gas inside the cover IA had simply expanded due to an increase in ambient temperature, rather than a tube breakage or the like, resulting in an increase in pressure.

Further, in S24, when the humidity sensor 18 detects an increase in humidity, the process moves to S29 and the output of the pressure sensor 19 is read. If the output of the pressure sensor 19 is normal at step 330, the process moves to step S31 and displays "inert gas shortage" on the display section 16.

This is because it was determined that since the humidity inside the cover IA had only increased, inert gas had leaked from the cover IA to the outside and air from the atmosphere had entered the cover IA. In this case, the operator replenishes the cover IA with inert gas.

Further, when the pressure sensor 19 detects a pressure increase in S30, the process moves to S32 and displays "Possibility of tube breakage" on the display section 16. This is sensor tube 5,6
This is because the humidity and pressure inside the cover IA increased even though the vibrations were normal, so it was determined that there was a possibility that the tube was slightly damaged. In this case, the operator removes the cover IA and examines the damaged state of the sensor tube 5.6.

Further, if there is an abnormality in the vibration of the sensor tube 5.6 in S22, the process moves to 333 and the output of the humidity sensor 18 is read. Next S34 and 333 read the humidity sensor 18.
If the output of the pressure sensor 19 is normal, the process moves to S35 and the output of the pressure sensor 19 is read.

If the pressure of the pressure sensor 19 is normal in the next step 336, the process moves to 337 and displays "bubbles mixed in" on the display section 16.

This is because although the humidity and pressure inside the cover IA are normal, only the vibration of the sensor tube 5.6 is abnormal, so it is determined that gas has accumulated inside the sensor tube 5.6. In this case, the operator bleeds the sensor tube 5.6 as necessary.

Further, when the pressure sensor 19 detects a pressure increase in S36, the process moves to 338 and displays "Possible tube damage" on the display section 16. This is because although the humidity inside the cover IA was normal, the vibration and pressure were abnormal, so it was determined that there was a possibility of tube damage. In this case, the operator removes the cover IA and examines the damaged state of the sensor tube 5.6.

In addition, when an increase in humidity is detected in S34, 33
9, the output of the pressure sensor 19 is read. next 34
If the pressure inside the cover IA is normal at 0, the process moves to S41 and displays "Possible tube damage" on the display section 16. This is because although the pressure inside the cover IA was normal, the vibration and humidity were abnormal, so it was determined that there was a possibility of tube damage. In this case, the operator must
Remove the sensor tube 5.6 and check the damage condition of the sensor tube 5.6.

Check the extent of damage to cover IA, and if damage is severe, replace cover IA.

Also, when a pressure increase is detected in S40, S42
Then, "Tube Damage" is displayed on the display section 16. This is because it was determined that the sensor tube 5.6 was damaged and the fluid flowed out from the sensor tube 5.6, since the vibration, humidity, and pressure were abnormal. In this case, the operator closes the main valve 4 and replaces it with a new mass flowmeter.

Further, the control circuit 23 may automatically close the main valve 4 or stop the pump 3 after S42.

In this way, by combining multiple phenomena with different properties, it becomes possible to determine the nature of the abnormality that has occurred in the mass flowmeter 1, and the operator can check the current status by looking at the display unit 16. . In addition, the operator can use the display section 16
Select a countermeasure according to the message displayed,
Appropriate measures can be taken depending on the nature of the abnormality.

In the above embodiment, it is not necessary to check the vibration of the sensor tube 5.6 and the humidity and pressure inside the cover IA, or to check the three types of phenomena. For example, it is of course possible to check vibration and humidity, or vibration and pressure.

Furthermore, in each of the embodiments, the amplitude monitoring circuit 31 for monitoring the amplitude of the sensor tube 5.6 is used as a vibration abnormality detection means. ) changes,
Since the vibration frequency changes, abnormality in vibration of the sensor tubes 5 and 6 may be detected by detecting the displacement of this vibration frequency. In addition, as a means other than the above, since the sensor tube 5.6 becomes difficult to vibrate due to damage to the sensor tube 5.6, the self-excited oscillation circuit 13 that receives the feedback signal from the pickup 10.11 sends a signal to the exciter 8.9. Since the applied voltage changes (increases), abnormal vibrations of the sensor tubes 5 and 6 may be detected by detecting this change, and an appropriate means can be used. Furthermore, the processing of the amplitude monitoring circuit 31 may be performed by a microcomputer. In this case, a program for this microcomputer processing is provided in the control circuit 23, and the detection signals from the pickups 10 and 11 are input directly to the control circuit 23. You can do it like this.

Effects of the Invention As described above, the mass flowmeter according to the present invention has a displacement detection means for detecting displacement of the sensor tube, detects vibration abnormality of the sensor tube, and detects the degree of deflection of the casing using a strain gauge. It is possible to determine whether the tube has been damaged or whether air bubbles have accumulated in the sensor tube, and it is possible to immediately take countermeasures depending on the nature of the abnormality after the occurrence of the abnormality.

In addition, the situation inside the housing can be monitored by a combination of the displacement means and a humidity sensor or a pressure sensor, and the content of the abnormality can be specifically confirmed based on the phenomenon where the abnormality occurred.
It has the advantage of being able to promptly implement countermeasures according to the nature of the abnormality when an abnormality occurs, and preventing damage from increasing due to delayed measures.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a first embodiment of a mass flowmeter according to the present invention, Fig. 2 is a flowchart for explaining abnormality processing executed by the control circuit, and Fig. 3 is a diagram of a second embodiment of the present invention. The configuration diagram and FIG. 4 are flowcharts for explaining abnormality processing executed by the control circuit shown in FIG. 3. l...mass flowmeter, IA...cover, 5,6...
Sensor tube, 7... tube, 8, 9... exciter, 1
0° 11...Pickup, 14...First strain gauge, 15...Second strain gauge, 16...Display section, 1
7... Support plate, 18... Humidity sensor, 19... Pressure sensor, 23... Control circuit (determination means, abnormality occurrence processing means). 31... Amplitude monitoring circuit (vibration abnormality detection means). Patent applicant: Tokiko Co., Ltd. Figure 2

Claims (3)

[Claims] (1) The sensor tube through which the fluid to be measured flows is housed in a sealed housing, the sensor tube is vibrated, and the displacement of the sensor tube due to the Coriolis force generated due to the vibration is detected by the displacement detection means. A mass flow meter that measures the flow rate of a fluid to be measured, comprising: a strain gauge that detects the degree of deflection of the housing; and a vibration abnormality detection means that detects abnormality in vibration of the sensor tube based on a detection signal of the displacement detection means. and determining means for determining whether or not the sensor tube is damaged based on the abnormality detection signal from the vibration abnormality detection means and the detection signal from the strain gauge, and when the determination means determines that an abnormality has occurred, an abnormality has occurred. A mass flowmeter characterized in that it is equipped with abnormality processing means for performing subsequent processing. (2) The sensor tube through which the fluid to be measured flows is housed in a sealed housing, the sensor tube is vibrated, and the displacement of the sensor tube due to the Coriolis force generated due to the vibration is detected by the displacement detection means. A mass flow meter that measures the flow rate of a fluid to be measured, comprising: a humidity sensor that detects humidity within the housing; and a vibration abnormality detection means that detects abnormality in vibration of the sensor tube based on a detection signal of the displacement detection means. , determination means for determining whether or not the sensor tube is damaged based on an abnormality detection signal from the vibration abnormality detection means and a detection signal from the humidity sensor; A mass flowmeter characterized by comprising: an abnormality occurrence processing means for processing. (3) The sensor tube through which the fluid to be measured flows is housed in a sealed housing, the sensor tube is vibrated, and the displacement of the sensor tube due to the Coriolis force generated due to the vibration is detected by the displacement detection means. A mass flow meter that measures the flow rate of a fluid to be measured, comprising: a pressure sensor that detects the pressure inside the housing; and a vibration abnormality detection means that detects an abnormality in vibration of the sensor tube based on a detection signal of the displacement detection means. , determining means for determining whether or not the sensor tube is damaged based on the abnormality detection signal from the vibration abnormality detection means and the detection signal from the pressure sensor; A mass flowmeter characterized by comprising: an abnormality occurrence processing means for processing.