KR20240003520A - Coriolismass flowmeter device and method for detecting resonance frequency - Google Patents

Abstract

The present invention relates to a resonant frequency detection device and method for a Coriolis mass flow meter, and more specifically, to a method for detecting the fluid or environment in a type of Coriolis mass flowmeter using two parallel flow tubes. It relates to a resonant frequency detection device and method for a Coriolis mass flow meter that finds the optimal resonant frequency within a certain range of the frequency of the vibrator, which is a driving means, without applying each frequency according to the above.
The present invention includes two flow tubes (1, 2) installed in a curved shape in parallel to the inlet manifold (24) and the outlet manifold (25), and an inlet side of the flow tubes (1, 2). Inlet and outlet side vibration detection sensors (16, 17) installed at a predetermined interval on the and outlet side, and resonance driving the flow tube (1, 2) between the inlet and outlet side vibration detection sensors (16, 17) It consists of a resonance frequency detection device equipped with a vibration oscillation unit (15);
In the CPU interface 50, the supply voltage is increased by 1Hz from the minimum frequency through the vibration oscillator 15, and the average size of the waveform detected by the input and outlet vibration detection sensors 16 and 17 is measured to determine the size of the waveform at the highest level. It is characterized by finding a large value, increasing the frequency again in 0.1hz units from a value 1Hz less than the corresponding frequency band, and calculating the flow rate by finding the frequency with the largest waveform.

Description

Coriolis mass flow meter resonance frequency detection device and method {CORIOLISMASS FLOWMETER DEVICE AND METHOD FOR DETECTING RESONANCE FREQUENCY}

The present invention relates to a resonant frequency detection device and method for a Coriolis mass flow meter, and more specifically, to a method for detecting the fluid or environment in a type of Coriolis mass flowmeter using two parallel flow tubes. It relates to a resonant frequency detection device and method for a Coriolis mass flow meter that finds the optimal resonant frequency within a certain range of the frequency of the vibrator, which is a driving means, without applying each frequency according to the above.

When one or both ends of an oil pipe through which the measured fluid flows are supported and the oil pipe is vibrated in a direction perpendicular to the flow direction of the oil pipe around the support point, the oil pipe (hereinafter, the oil pipe to which vibration is applied is called a flow tube) ) is well known. The shape of the flow tube in this Coriolis mass flow meter is roughly divided into a curved tube and a straight pipe.

When the straight pipe type Coriolis mass flow meter vibrates in a direction perpendicular to the axis of the central portion of the straight pipe supported at both ends, the displacement difference of the straight pipe due to the Coriolis force between the support part and the central portion of the straight pipe, that is, the phase difference signal. It detects the mass flow rate. This type of straight-type Coriolis mass flow meter has a simple, compact, and robust structure, but cannot achieve high detection sensitivity.

In contrast, a curved tube type Coriolis mass flow meter can detect mass flow rate with high sensitivity because it can select a shape to effectively utilize the Coriolis force. Additionally, in order to drive this curved measuring tube more efficiently, it is also known to have two curved tubes through which the measuring fluid flows in parallel configuration.

The schematic configuration of such a conventional two parallel curved tube type Coriolis mass flow meter is that the flow tubes (1, 2) are composed of two parallel curved tubes (U-tubes) and a driving device composed of a coil and a magnet at the center. By (15), these two flow tubes (1, 2) are driven in resonance with each other in opposite phases. In addition, a pair of vibration detection sensors 16 and 17 consisting of a coil and a magnet are installed in symmetrical positions on both left and right sides with respect to the installation position of the drive device 15 and detect a phase difference proportional to the Coriolis force.

The measured fluid flows into the tube-shaped body from an external flow pipe connected through a flange on the inlet side, where the direction is changed by 90 degrees by an end plate and branches equally into the two flow tubes (1, 2). It becomes (分岐). The branched fluids merge at the outlet side of the flow tubes (1, 2), and at the same time, their direction is changed by 90 degrees by the end plate (36) and flow out into an external flow pipe connected through the flange (19) on the outlet side. In this way, by allowing the measured fluid to flow equally through the two flow tubes (1, 2), the natural frequencies of the two flow tubes (1, 2) can always be made the same even if the type of fluid changes and the temperature fluctuates. Accordingly, it is known that it is possible to construct a Coriolis mass flow meter that can be operated efficiently and stably and at the same time is free from the influence of external vibration or temperature.

However, the conventional Coriolis mass flow meter using a flow tube consisting of two parallel curved tubes was not perfect in isolation of vibration transmission from the outside.

As shown, base plates 27, 28 are installed on the two flow tubes 1 and 2, and this point becomes the first point of vibration (fulcrum), and at the same time, the two flow tubes 1 and 2 ) and the main body 34 are the second points of flow tube vibration, and these two points are the important basis for the entire tube vibration. However, the second point was not isolated from external vibration transmission, and external vibration was transmitted from the main body structure and case, etc., adversely affecting the performance of the Coriolis mass flow meter.

In addition, the Coriolis mass flow meter using a flow tube consisting of two parallel curved tubes has a branching portion at the measurement fluid inlet and a confluence portion at the measurement fluid outlet due to its structure, Here, there is a problem of pressure loss or clogging of the fluid. This is especially problematic for highly viscous fluids, or liquids that are prone to corrosion and clogging, such as food.

In addition, this type of Coriolis mass flow meter has a low cost and robust structure to prevent any emergency in the tube.

It is necessary to make it reliable even against breakage, but this point has not been sufficiently taken into account in conventional Coriolis mass flow meters.

In addition, the conventional Coriolis mass flow meter did not take into account the influence of high-order vibration modes that necessarily exist in a vibrating flow tube.

The vibration oscillation unit 15, which is a driving device that drives the flow tubes 1 and 2 composed of two parallel curved tubes at the center, is usually composed of a coil and a magnet. The coil of the vibration oscillator 15 is installed on one of the two flow tubes (1, 2), and the magnet is installed on the other flow tube, and the two flow tubes (1, 2) are driven to resonate in opposite phases. do. In addition, a pair of vibration detection sensors 16 and 17 are composed of a coil and a magnet, are installed in symmetrical positions on both left and right sides with respect to the installation position of the vibration oscillator 15, and detect a phase difference proportional to the Coriolis force. The coils and magnets of these sensors are also installed separately through fixtures, with the coil on one side of the flow tube and the magnet on the other side of the flow tube.

For these vibration oscillator units 15 and the pair of vibration detection sensors 16 and 17, only the coil requires wiring, and the magnet does not require wiring. Wiring was laid only on the surface of the flow tube where the coil was installed. However, the conventional Coriolis mass flow meter does not consider the effect of such wiring on the vibration of the flow tube, and focuses the coils of the vibration oscillator 15 and a pair of vibration detection sensors 16 and 17 on one flow tube. and installed it. As a result, the influence of the mass and tension of the wiring was concentrated only on the tube where the coil was installed, thereby worsening the balance of the two flow tubes and adversely affecting the performance of the Coriolis mass flow meter.

To prevent these defects, Patent Registration No. 0327557 (registered on February 22, 2002) is a Coriolis mass flow meter consisting of two parallel curved tubes, two flow tubes (1, 2), a vibration oscillator (15), and a pair of vibration detection sensors 16 and 17. An inlet manifold (24) that diverges the measurement fluid from the inlet to the two flow tubes (1, 2), and an outlet side that joins the measurement fluid flowing in the two flow tubes (1, 2) and discharges it from the measurement fluid outlet. The manifold 25 is mechanically coupled to the main body 30 only on the inlet side of the inlet manifold 24 and on the outlet side of the outlet manifold 25. According to this arrangement, at each coupling end of the inlet and outlet manifolds 24, 25 and the flow tubes 1 and 2, which are vibration points, the vibration is transmitted from the main body 30 and all structures coupled to the main body. The effect of vibration was reduced.

However, because these conventional flow meters provide memorized frequencies, there is a drawback in that each frequency must be applied depending on the fluid or environment used.

[Document 1] Patent Registration No. 0327557 (registered on February 22, 2002) [Document 2] Patent Registration No. 2388592 (registered on April 15, 2022) [Document 3] Patent Registration No. 2388598 (registered on April 15, 2022) [Document 4] Patent Registration No. 1932939 (registered on December 20, 2018)

Therefore, it was designed to solve these conventional shortcomings, and the problem of the present invention is to increase the frequency by a certain amount from the vibration oscillator and measure the signal specified from the two sensors with the pickup input. The purpose is to find an appropriate natural frequency using a high-performance processor by taking advantage of the characteristic that the amplitude increases rapidly at the frequency.

Another problem solved by the present invention is to find the resonance frequency of each product by programming the mass flow meter with an automatic search (Outo Searching) function because the resonance frequency is slightly different.

The present invention includes two flow tubes installed in a curved form in parallel on an inlet manifold and an outlet manifold, and an inlet and outlet vibration detection sensor installed at a predetermined distance between the inlet and outlet sides of the flow tube. and a resonance frequency detection device that installs a vibration oscillation unit for resonance driving on the flow tube between the inlet and outlet vibration detection sensors;

In the CPU interface, the supply voltage is increased by 1Hz from the minimum frequency through the vibration oscillator, and the average size of the waveform detected by the vibration detection sensor at the input and exit is measured to find the value with the largest waveform size, and 1Hz smaller than the corresponding frequency band. It is characterized by calculating the flow rate by increasing the frequency again in 0.1hz increments from the value and finding the frequency with the largest waveform.

The present invention uses an input voltage of AC 220V or DC 24V, and includes a frequency input step of supplying ±5VDC and 3.3VDC inside the mass flow meter;

A oil supply step of supplying fluid through the inlet and outlet manifolds connected to the mass flow meter to close the valves at the front and rear ends of the mass flow meter so that the fluid fills the internal flow tube of the mass flow meter;

To find the natural frequency for each product, the CPU interface (Micorprocessor) starts from the minimum value of the frequency preset in the vibration oscillator and increases the frequency at regular intervals to find the optimal frequency (natural frequency);

When the vibration oscillator is excited at a specific frequency, vibration is transmitted to the entire flow tube, and the vibration is also transmitted to the inlet vibration detection sensor (Pickup Input) installed at the front of the flow tube and the outlet vibration detection sensor (Pickup Output) installed at the rear. A vibration transmission step;

Waveform average size measurement step in which the average size of the Pickup Input/Output waveform is measured by increasing the minimum frequency by 1 Hz with the same force (supply voltage) through the vibration oscillator according to the program in the CPU interface 50 consisting of a microprocessor. ;

A flow rate calculation step of calculating the flow rate by finding the oscillation frequency through the waveform average size measurement step, detecting the phase difference at this time, and applying it to the programmed formula; It includes.

In the vibration transmission step, the frequencies measured by each sensor are in phase. The optimal frequency (resonant frequency) described above includes the frequency at which the size (Vpp) of the waveform measured by the two inlet and outlet vibration detection sensors becomes the largest when the vibration oscillator is excited with the same force.

The waveform average size measurement step measures the average size of the waveform to find the value with the largest waveform size, and increases the frequency in 0.1hz units from a value 1hz smaller than the corresponding frequency band to find the frequency with the largest waveform. , When fluid flows through the flow tube, the double-pipe flow tube, which was constantly vibrating from the vibrating oscillator, is slightly distorted due to the flow of fluid, and the signals from the vibration detection sensors on the inlet and outlet sides generate a phase difference, This phase difference is called △T and includes the occurrence of a larger phase difference when the flow rate increases.

In the present invention, the vibration generation unit (Function Generation) increases the frequency by a certain amount and supplies it, and when the specified signal from the two inlet and outlet vibration detection sensors installed on the flow tube is measured as a pickup input, the natural frequency is By taking advantage of the characteristic of rapidly rising amplitude, a high-performance processor is used to find the most appropriate natural frequency in a short time, thereby improving the accuracy of measurement by obtaining the highest signal at the same force.

In the present invention, since the resonant frequency is slightly different because a large difference occurs in the inlet vibration detection sensor (pickup sensor) even with a small change, the mass flow meter programs an automatic search (Outo Searching) function to determine the resonant frequency of each product. The goal is to find the most suitable signal in a short period of time and improve accuracy through the strongest signal.

1 is a front view of a mass flow meter showing a preferred embodiment of the present invention.
Figure 2 is a plan view of a mass flow meter showing the installation state of the present invention
Figure 3 is a block diagram showing an embodiment of the present invention.
Figure 4 is a waveform diagram of the state providing a frequency of 157Hz of the present invention
Figure 5 is a waveform diagram showing the frequency of the present invention at 157.1Hz.
Figure 6 is a waveform diagram showing the frequency of the present invention at 157.2Hz.
Figure 7 is a block diagram showing the most preferred embodiment of the present invention.

The above objects, other objects, features and advantages of the present invention will be easily understood through the following preferred embodiments related to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content will be thorough and complete and so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art.

In this specification, when an element is referred to as being on another element, it means that it may be formed directly on the other element or that a third element may be interposed between them. Also, in the drawings, the thickness of components is exaggerated for effective explanation of technical content.

Embodiments described herein will be explained with reference to cross-sectional views and/or plan views, which are ideal illustrations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for effective explanation of technical content. Therefore, the shape of the illustration may be changed depending on manufacturing technology and/or tolerance. Accordingly, embodiments of the present invention are not limited to the specific form shown, but also include changes in form produced according to the manufacturing process. For example, an area shown as a right angle may be rounded or have a shape with a predetermined curvature. Accordingly, the regions illustrated in the drawings have properties, and the shapes of the regions illustrated in the drawings are intended to illustrate a specific shape of the region of the device and are not intended to limit the scope of the invention. In various embodiments of the present specification, terms such as first and second are used to describe various components, but these components should not be limited by these terms. These terms are merely used to distinguish one component from another. Embodiments described and illustrated herein also include complementary embodiments thereof.

The terminology used herein is for describing embodiments and is not intended to limit the invention. As used herein, singular forms also include plural forms, unless specifically stated otherwise in the context. As used in the specification, 'comprises' and/or 'comprising' does not exclude the presence or addition of one or more other elements.

In describing specific embodiments below, various specific details have been written to explain the invention in more detail and to aid understanding. However, a reader with sufficient knowledge in the field to understand the present invention can recognize that it can be used without these various specific details. In some cases, it is mentioned in advance that when describing the invention, parts that are commonly known but are not significantly related to the invention are not described in order to prevent confusion without any reason in explaining the invention.

Hereinafter, preferred embodiments of the present invention will be described in more detail according to the attached drawings.

Figure 1 is a front view of a mass flow meter showing a preferred embodiment of the present invention, and Figure 2 is a plan view of the mass flow meter showing the installation state of the present invention.

The Coriolis mass flow meter 100 includes two flow tubes 1 and 2 consisting of two parallel curved tubes.

The vibration oscillation unit 15 oscillates one flow tube 1 with respect to the other flow tube 2 in opposite phases, while a pair of inlet and outlet vibration detection sensors 16 and 17 vibrate. It is installed in symmetrical positions on both left and right sides with respect to the installation position of the oscillator 15 and detects a phase difference proportional to the Coriolis force. The inlet manifold (24) diverges the measurement fluid from the inlet to the two flow tubes (1, 2), and the outlet manifold (25) diverts the measurement fluid flowing into the two flow tubes (1, 2). It merges and flows out from the outlet. In such a Coriolis mass flow meter, the inlet and outlet manifolds 24 and 25 are mechanically connected to the main body 30 only on the inlet side of the inlet manifold 24 and the outlet side of the outlet manifold 25. It is combined. Accordingly, the main body 30 and the main body 30 are connected to the main body at each coupling end of the inlet and outlet manifolds 24, 25 and the flow tubes 1 and 2, which are vibration points. The effects of vibration transmission from all structures can be reduced.

In this way, the present invention is configured to isolate the connection portion between the flow tubes (1, 2) and the main body (30), which is the point of vibration of the flow tubes (1, 2), from vibration transmission from the outside, thereby preventing high vibration. It can provide stability and a high-precision Coriolis mass flow meter.

In addition, the present invention smoothly changes direction of the fluid passages of the inlet manifold 24 and the outlet manifold 25 by drawing an arc at each inlet or outlet, while maintaining the total cross-sectional area of the fluid passages continuously. change it to Accordingly, there is no pressure loss or fluid blockage at the branch or confluence of the measured fluid.

In addition, the present invention can be configured not to have a special natural frequency by forming the inlet manifold 24 and the outlet manifold 25 into a continuously enlarged and curved block shape, and thus to prevent disturbance vibration (external vibration). It includes something that can be configured not to vibrate easily without amplifying the movement.

In addition, the present invention has a box-shaped structure in which the connection ports at both ends and the main body 30, which supports the entire flowmeter, has a U-shaped cross-section and a base plate is placed on the top so as not to contact the vibration point, thereby preventing bending. It is made with a structure that is resistant to bending or twisting, and external stress on the connection does not affect the vibration of the tube. It provides a high-precision flow meter, and at the same time, it can be constructed at a low cost by making the body thin. there is.

In addition, the present invention is provided with a U-shaped pressure-resistant case 31 that is integrally combined with the main body 30 and has an arc shape on all outer circumferences, thereby securing a very high internal pressure despite being thin, and preventing the occurrence of an emergency. This includes being able to construct a reliable pressure-resistant container even in the event of damage to the tube.

In addition, the present invention disposes the vibration oscillator 15 and a pair of inlet and outlet vibration detection sensors 16 and 17 on the central axis of the tube between the two flow tubes 1 and 2, thereby generating inertia due to the vibration inertial force. Moments can be prevented from occurring.

In addition, the present invention arranges the installation position of the pair of inlet and outlet vibration detection sensors 16 and 17 at the nodes of the secondary vibration mode in each part of the inlet and outlet sides. This includes completely securing the symmetry of the vibration beam without being affected by the secondary vibration mode, and at the same time isolating the entry of vibration from the outside to the limit.

In addition, the present invention is a flexible printed circuit board ( By using 12) and making the added mass and added stress symmetrical, very stable vibration can be obtained and at the same time, very high precision can be obtained since it is not affected by vibration from the outside.

In addition, the Coriolis mass flow meter 100 of the present invention has its front end face opposed to the vibration oscillation unit 15 installed in the center of the flow tubes 1 and 2, and at the same time, it has a support (which has a wire for wiring inserted into the inside). A pole 10 is installed, and the front end of the support 10 is connected to the coil of the driving device by a first flexible printed board 12, and a pair of mouths are formed by a second flexible printed board 12. From the coil of the outlet vibration detection sensor (16, 17) to the wiring (Teflon wire) installed along the surface of the flow tube (1, 2), approximately at the center of the flow tube (1, 2) with respect to the center of vibration of each flow tube. Connect by bending to a symmetrical position.

In this way, the rigidity and shape of the flexible printed board 12, especially for the wiring from the flow tubes 1 and 2 to the support, are made almost the same, and the flexible printed board 12 is divided into two flow tubes 1 and 2, respectively. Not only can the influence on the flow tubes (1, 2) of (12) be dispersed, but the width of the flexible printed board (12) can be narrowed, and thus the flow tubes (1, 2) of the flexible printed board (12) can be narrowed. ) can also be done in the same way while minimizing the impact on

Figure 3 is a block diagram showing an embodiment of the present invention, Figure 4 is a waveform diagram in a state of providing a frequency of 157Hz of the present invention, Figure 5 is a waveform diagram of a state of providing a frequency of 157.1Hz of the present invention, and Figure 6 is a waveform diagram of a state providing a frequency of 157.1Hz of the present invention. This shows the waveform diagram of the state in which the frequency of the present invention is provided at 157.2Hz.

The vibration oscillation unit 15, which is the drive means, finds the optimal resonance frequency within a certain frequency range. The vibration oscillation unit 15 increases the frequency by a certain amount and supplies it, and the two inlet vibration detection sensors 16 When the signal specified from the vibration detection sensor 17 on the outlet side is measured by the pickup input on the inlet side, the most suitable natural frequency is determined in a short time using a high-performance processor using the characteristic that the amplitude increases rapidly at the natural frequency. This includes installing it so that it can be found.

A more specific test method is to input a variable frequency of 3VPP voltage using the vibration oscillator 15.

The signal vibrated by the vibration oscillator 15 is acquired from the input and output vibration detection sensors 16 and 17, and in the case of the resonance frequency, the highest (strongest) signal can be obtained at the same force.

The input voltage is AC 220V or DC 24V, and a frequency input step (S10) is performed to supply ±5VDC and 3.3VDC inside the mass flow meter 100.

By supplying fluid through the inlet and outlet manifolds (24, 25) connected to the mass flow meter (100), the valves at the front and rear ends of the mass flow meter (100) are closed so that the fluid flows into the internal flow tube (1, Perform the rapeseed supply step (S20) to fill 2).

In order to find the natural frequency for each product, the CPU interface (Micorprocessor, 50) starts from the minimum value of the frequency preset in the vibration oscillator 50 and increases the frequency at regular intervals to find the optimal frequency (natural frequency). The frequency finding step (S30) is performed.

At this time, the measured natural frequency is measured differently depending on the physical characteristics of the flow tubes 1 and 2 composed of a double pipe and the fluid used.

As described above, when the vibration oscillator 15 is excited at a specific frequency, vibration is transmitted throughout the flow tubes 1 and 2, and the inlet vibration detection sensor (Pickup Input) installed at the front of the flow tubes 1 and 2 , 16) and the exit side vibration detection sensor (Pickup Output, 17) installed at the rear end to perform the vibration transmission step (S40) so that the vibration is transmitted.

At this time, the frequencies measured by each sensor 16 and 17 are in phase. The optimal frequency (resonant frequency) described above is the size (Vpp) of the waveform measured at the two inlet and outlet vibration detection sensors 16 and 17 when excited with the same force in the vibration oscillator 15. It means increasing frequency.

The main element of the present invention lies in a method for automatically finding the above natural frequency. Waveform average that measures the average size of the Pickup Input/Output waveform by increasing the minimum frequency by 1 Hz with the same power (supply voltage) through the vibration oscillator 15 according to the program in the CPU interface 50 made of a microprocessor. The size measurement step (S50) is performed.

Measure the average size of the waveform to find the value with the largest waveform size, and increase the frequency in 0.1hz units from a value 1hz smaller than the corresponding frequency band to find the frequency with the largest waveform.

Here, the size of the waveform before and after the resonant frequency shows a significant difference from the waveform at the resonant frequency.

When fluid flows through the flow tubes (1, 2), the flow tubes (1, 2) in the form of a double pipe, which are constantly vibrated by the vibration oscillator (15), are slightly distorted due to the flow of fluid. At this time, the signals from the inlet and outlet vibration detection sensors 16 and 17 generate a phase difference. This phase difference is called △T, and as the flow rate increases, a larger phase difference occurs.

The flow rate calculation step (S60) is performed to find the oscillation frequency through the waveform average size measurement step (S50), detect the phase difference at this time, and apply it to the programmed formula to calculate the flow rate.

By calculating the flow rate, the flow of fluid can be calculated quickly and precisely.

As shown in the waveforms (purple) of Figures 4 to 6, when only the frequency is changed to 157Hz, 157.1Hz, and 157.2Hz under the same voltage condition of 3VPP in the vibration oscillator 15, the peak-to-peak of the inlet vibration detection sensor 16 The strongest signal was output at a voltage of 157.1Hz, and this frequency is called the resonant frequency of the tested product.

Even a small change of 0.1 Hz in the frequency of the vibration oscillator 15 causes a large difference in the pickoff sensor.

Since the resonant frequency of each product is slightly different, the mass flow meter 100 can program an automatic search function to find the most appropriate resonant frequency of each product easily and quickly, so that when the fluid flows, the linearity and flow of the fluid By using the resonant frequencies of the tubes 1 and 2, the applicability of a flow meter that applies the mass flow effect using the distortion phenomenon of the flowing fluid is secured, making it possible to precisely measure the flow of fluid.

The present invention is intended to be applied to hydrogen, and when applied to hydrogen, a high rate of return can be recorded, but since the quantity is very limited, it is desirable to expand the product line to gas and petrochemicals.

The present invention is to find the optimal resonance frequency within a certain range of frequencies in the vibration oscillator. The vibration oscillator increases the frequency of a certain amplitude and supplies it, and when the signal specified from the vibration detection sensor at the inlet and outlet is measured as a pickup input, the natural frequency is determined. This provides a very useful invention that can precisely measure the flow of fluid by finding the most appropriate natural frequency in a fast new volume using a high-performance processor by using the characteristic of a sudden increase in amplitude.

1, 2: flow tube 10: support
12: printed board 15: vibration oscillation unit
16: Inlet vibration detection sensor 17: Exit vibration detection sensor
24: inlet manifold 25: outlet manifold
30: Main body 50: CPU interface

Claims (4)

Two flow tubes (1, 2) are installed in a curved shape in parallel to the inlet manifold (24) and the outlet manifold (25), and predetermined tubes are installed on the inlet and outlet sides of the flow tubes (1, 2). Inlet and outlet side vibration detection sensors (16, 17) installed at an interval of ) and a resonant frequency detection device installed;
In the CPU interface 50, the supply voltage is increased by 1Hz from the minimum frequency through the vibration oscillator 15, and the average size of the waveform detected by the input and outlet vibration detection sensors 16 and 17 is measured to determine the size of the waveform at the highest level. A resonance frequency detection device for a Coriolis mass flow meter, characterized by finding a large value, increasing the frequency in 0.1hz units from a value 1Hz smaller than the corresponding frequency band, and calculating the flow rate by finding the frequency with the largest waveform.
The input voltage is AC 220V or DC 24V, and a frequency input step (S10) that supplies ±5VDC and 3.3VDC inside the mass flow meter 100;
By supplying fluid through the inlet and outlet manifolds (24, 25) connected to the mass flow meter (100), the valves at the front and rear ends of the mass flow meter (100) are closed so that the fluid flows into the internal flow tube (1, 2) supply of rapeseed to be filled (S20);
In order to find the natural frequency for each product, the CPU interface (Micorprocessor, 50) starts from the minimum value of the frequency preset in the vibration oscillator 50 and increases the frequency at regular intervals to find the optimal frequency (natural frequency). Frequency finding step (S30);
When the vibration oscillator 15 is excited at a specific frequency, vibration is transmitted throughout the flow tubes 1 and 2, and the inlet vibration detection sensor (Pickup Input, 16) installed at the front end of the flow tubes 1 and 2 and the rear end A vibration transmission step (S40) in which vibration is transmitted to the outlet side vibration detection sensor (Pickup Output, 17) installed in;
Waveform average that measures the average size of the Pickup Input/Output waveform by increasing the minimum frequency by 1 Hz with the same power (supply voltage) through the vibration oscillator 15 according to the program in the CPU interface 50 made of a microprocessor. Size measurement step (S50);
A flow rate calculation step (S60) of finding the oscillation frequency through the waveform average size measurement step (S50), detecting the phase difference at this time, and applying it to the programmed formula to calculate the flow rate; A method of detecting the resonant frequency of a Coriolis mass flow meter including.
According to clause 2,
In the vibration transmission step (S40), the frequencies measured by each sensor 16 and 17 are in phase. The optimal frequency (resonant frequency) described above is the size (Vpp) of the waveform measured at the two inlet and outlet vibration detection sensors 16 and 17 when excited with the same force in the vibration oscillator 15. Method for detecting resonant frequency of Coriolis mass flow meter including increasing frequency.
According to clause 2,
In the waveform average size measurement step (S50), the average size of the waveform is measured to find the value with the largest waveform size, and the frequency is increased in 0.1hz units from a value 1hz smaller than the corresponding frequency band to reach the frequency with the largest waveform. is to find, and when the fluid flows through the flow tubes (1, 2), the double pipe-shaped flow tubes (1, 2), which were constantly vibrated from the vibration oscillator (15), are slightly distorted by the flow of fluid, and the mouth, The signal from the outlet vibration detection sensor (16, 17) generates a phase difference, and this phase difference is called △T, which is the resonance frequency of the Coriolis mass flow meter, which includes generating a larger phase difference when the flow rate increases. Detection method.

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