Mass flow meter

Abstract

The application provides a mass flowmeter, the mass flowmeter comprising a measuring assembly, the measuring assembly having a first modal frequency ω1 and a second modal frequency ω2, the first modal frequency ω1 and the second modal frequency ω2 satisfying: 0.8≤ω1 / ω2≤1.2, wherein the first modal frequency ω1 corresponds to a Coriolis mode of the measuring assembly, and the second modal frequency ω2 corresponds to a driving mode of the measuring assembly. The mass flowmeter has a high signal-to-noise ratio, and the zero point stability of the mass flowmeter is high.

Description

Technical Field

[0001] This application relates to the field of fluid metering equipment technology, and in particular to a mass flow meter. Background Technology

[0002] A Coriolis mass flow meter is an instrument that directly and precisely measures the mass flow rate of a fluid. It has at least one measuring tube for fluid flow, at least one vibrator to drive the measuring tube to vibrate, and at least two pickup sensors to obtain the phase difference between the measuring tube at the inlet and outlet ends.

[0003] The zero-point stability of a mass flow meter has a significant impact on its accuracy and repeatability. One factor affecting zero-point stability is the signal-to-noise ratio (SNR), especially in gas applications. Due to the higher flow velocity and lower mass flow rate of the fluid passing through the measuring tube, the SNR is much lower in gas applications than in liquid applications, thus limiting the use of mass flow meters in gas measurement. Therefore, a solution to improve the SNR of mass flow meters is urgently needed. Utility Model Content

[0004] Based on this, this application provides a mass flow meter to address the shortcomings of related technologies.

[0005] The mass flow meter provided in this application includes:

[0006] The measurement component has a first modal frequency ω1 and a second modal frequency ω2, wherein the first modal frequency ω1 and the second modal frequency ω2 satisfy: 0.8≤ω1 / ω2≤1.2;

[0007] Wherein, the first modal frequency ω1 corresponds to the Coriolis mode of the measurement component, and the second modal frequency ω2 corresponds to the driving mode of the measurement component.

[0008] In one possible implementation, the first mode frequency ω1 and the second mode frequency ω2 satisfy: |ω1-ω2|≥10Hz and At least one of them,

[0009] In one possible implementation, the measuring component includes: at least one measuring tube configured to allow the flow of the fluid to be measured, the measuring tube having a third modal frequency ω3, the third modal frequency ω3 corresponding to the Coriolis mode of the measuring tube, and the first modal frequency ω1 and the third modal frequency ω3 satisfying:

[0010] -5%≤(ω1-ω3) / ω3≤5%.

[0011] In one possible implementation, the measuring tube has a fourth modal frequency ω4, which corresponds to the driving mode of the measuring tube. The second modal frequency ω2 and the fourth modal frequency ω4 satisfy the following:

[0012] (ω2-ω4) / ω2≥50%.

[0013] In one possible implementation, the measuring assembly also includes a stiffness enhancement unit connected to the measuring tube.

[0014] In one possible implementation, the thickness direction of the stiffness reinforcement unit is aligned with the extension direction of the measuring tube, and the midpoint of the stiffness reinforcement unit in its thickness direction is located within the middle of the extension direction of the measuring tube.

[0015] Wherein, along the extension direction of the measuring tube, the extension length of the measuring tube is L, the midpoint of the measuring tube is at L / 2, and the middle part of the extension direction of the measuring tube is (1 / 2±20%)*L.

[0016] In one possible implementation, the weight m1 of the stiffness enhancement unit and the weight m2 of the measuring tube satisfy the following condition: m1 ≤ 20% m2.

[0017] In one possible implementation, the mass flow meter further includes a housing and a support tube, with a stiffening reinforcement unit bridged between the measuring tube and the housing, or between the measuring tube and the support tube, or between the two measuring tubes.

[0018] In one possible implementation, the stiffness enhancement unit includes at least one stiffness enhancement member, which includes two first connecting parts and a second connecting part, with the first connecting parts corresponding to the measuring tubes one-to-one.

[0019] Alternatively, the stiffness reinforcement includes a first connecting part, a second connecting part, and a third connecting part connected in sequence, wherein the first connecting part is connected to the measuring tube, and one of the housing and the support tube is connected to the third connecting part.

[0020] In one possible implementation, the first connecting part is provided with a contact surface that contacts the outer wall of the measuring tube;

[0021] The contact surface is a concave arc surface, and the diameter of the contact surface matches the outer diameter of the measuring tube.

[0022] In one possible implementation, the area S1 of the contact surface and the average cross-sectional area S2 of the second connection portion on each reference plane satisfy: S1 / S2≥2;

[0023] Each reference plane is perpendicular to the extension direction of the second connecting portion at its corresponding position.

[0024] The mass flow meter provided in this application includes a measuring component. By setting the measuring component to measure fluid, the mass flow rate of the fluid is measured through the Coriolis effect. Since the ratio of the first modal frequency to the second modal frequency of the measuring component is between 0.8 and 1.2, the second modal frequency of the measuring component is close to the first modal frequency, thereby improving the mass flow measurement effect of the measuring component. Therefore, the mass flow meter provided in this application has a high signal-to-noise ratio and high zero-point stability.

[0025] In addition to the technical problems solved by the embodiments of this application, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions described above, other technical problems that the mass flow meter provided by this application can solve, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further explained in detail in the specific embodiments. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a mass flow meter provided in an embodiment of this application;

[0028] Figure 2 Another structural schematic diagram of the mass flow meter provided in the embodiments of this application;

[0029] Figure 3 for Figure 2 A magnified view of a section at point A in the middle;

[0030] Figure 4 This is a schematic diagram of the structure of the support tube and measuring components in the mass flow meter provided in the embodiments of this application;

[0031] Figure 5 for Figure 4 A magnified view of a section at point B in the middle;

[0032] Figure 6 This is a schematic diagram of the internal structure of a mass flow meter provided in an embodiment of this application;

[0033] Figure 7 for Figure 6 A magnified view of a section at point C;

[0034] Figure 8A schematic diagram of the stiffness reinforcement component in the mass flow meter provided in this application embodiment. Figure 1 ;

[0035] Figure 9 A schematic diagram of the stiffness reinforcement component in the mass flow meter provided in this application embodiment. Figure 2 ;

[0036] Figure 10 A schematic diagram of the stiffness reinforcement component in the mass flow meter provided in this application embodiment. Figure 3 ;

[0037] Figure 11 A schematic diagram of the stiffness reinforcement component in the mass flow meter provided in this application embodiment. Figure 4 ;

[0038] Figure 12 A schematic diagram of the stiffness reinforcement component in the mass flow meter provided in this application embodiment. Figure 5 ;

[0039] Figure 13 for Figure 8 The main view;

[0040] Figure 14 for Figure 13 DD cross-sectional view;

[0041] Figure 15 for Figure 12 The main view;

[0042] Figure 16 for Figure 15 EE cross-sectional view.

[0043] Explanation of reference numerals in the attached figures:

[0044] 100 - Measuring component; 110 - Measuring tube; 120 - Stiffness reinforcement unit; 121 - Stiffness reinforcement component; 1211 - First connecting part; 1211a - Contact surface; 1212 - Second connecting part; 1212a - Cross section; 1213 - Third connecting part;

[0045] 200-Phase detection component;

[0046] 300 - Vibration exciter;

[0047] 400 - Temperature sensing element;

[0048] 500-Support tube;

[0049] 600 - Housing. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0051] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0052] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0053] The terms "first," "second," and "third" (if any) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0054] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or display that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or display.

[0055] As described in the background section, the performance of a mass flow meter depends on its accuracy and repeatability. The measurement error of a mass flow meter consists of two parts: linearity error and zero-point error. While mass flow meters generally exhibit good linearity, zero-point stability and the resulting errors affect the measurement and practicality of small flow rates. One factor affecting zero-point stability is the signal-to-noise ratio, especially in gas applications. Because the fluid passing through the measuring tube often has a high velocity and a small mass flow rate, the signal-to-noise ratio is much lower than in liquid applications. For these reasons, the application of mass flow meters in gas measurement is limited. For example, the density of hydrogen is much lower than that of nitrogen and natural gas, other commonly used industrial gases, resulting in poor measurement performance of hydrogen by existing mass flow meters.

[0056] In some applications, such as volumetric provising in the oil and gas industry, the repeatability requirements for mass flow meters even exceed their accuracy requirements. One of the key factors determining the repeatability of a mass flow meter is the signal-to-noise ratio (SNR) of the sensor's received signal. Signal noise is related to the measurement medium (such as noise from the high-speed fluid itself) and the measurement environment (such as vibration or electromagnetic interference). The mass flow meter itself has limited effectiveness in reducing signal noise. Therefore, one of the key methods to improve the SNR is to significantly improve the mass flow meter's sensitivity to signals without significantly reducing signal noise, while simultaneously not amplifying the mass flow meter's sensitivity to noise.

[0057] The following is a brief introduction to the basic working principle of the mass flow meter and the inventive concept of this application.

[0058] When the mass flow meter is working stably, its motion characteristics can be represented by a single-degree-of-freedom vibration differential equation, and the mass flow meter has a drive mode and a Coriolis mode.

[0059] The following describes the driving modes of mass flow meters:

[0060]

[0061] Where, m D It is the effective quality in drive mode; C D It is the damping coefficient in drive mode; K D It measures the stiffness of the tube in drive mode, F D It is the driving force in drive mode.

[0062] In addition, in the formula For vibration acceleration, Let Y be the vibration velocity and Y be the vibration displacement. Due to simple harmonic motion, the displacement at the sensor position Y can be described as:

[0063] Y D =Y D e jωt (1-2)

[0064] in, Y D It is the complex amplitude of the oscillation.

[0065] Due to F D With damping term The characteristic frequency of the driving mode can be calculated using equations (1-1) and (1-2) to cancel out the loss:

[0066]

[0067] It should be noted that ω D This corresponds to the first natural resonant frequency, which is the symmetrical drive mode of the measuring tube. The operating frequency of the mass flow meter is usually adjusted to be as close as possible to this frequency to save drive energy; that is, the operating frequency of the mass flow meter is equal to or approximately equal to the first natural resonant frequency of the measuring tube.

[0068] The Coriolis mode of mass flow meters is described below:

[0069] Similarly, the measurement effect of the mass flow meter can be derived, and the following differential equation describes the motion of the measuring tube at the pickup sensor position:

[0070]

[0071] Y C = Y C e jωt (1-5)

[0072] Effective Coriolis force F C :

[0073] F C = F C e jωt (1-6)

[0074] Similarly, suppose F C With damping term Cancellation yields the characteristic frequencies of the Coriolis mode:

[0075]

[0076] Pick up sensor location F C The magnitude of the effective Coriolis force can be calculated by integrating along the measuring tube; the results are presented below:

[0077]

[0078] Where, k GIt is a coupling factor that takes into account the shape of the oscillation mode.

[0079] The Coriolis displacement can be obtained by solving the equation of motion (1-4) using equations (1-5) to (1-8).

[0080]

[0081] Where Q is the quality factor, characterized as

[0082] The variation is:

[0083]

[0084] Where Δτ represents the time difference when the two pickup sensors located at the inlet and outlet ends of the measuring tube cross the centerline. Therefore, the formula for calculating the mass flow rate of the measured fluid by physically measuring Δτ is:

[0085]

[0086] Where C is the correction factor (also known as the instrument coefficient), which is independent of the fluid properties under ideal conditions, and the manufacturer calibrates each mass flow meter.

[0087] As can be seen from the above, especially based on equation (1-9), it can be inferred that when the mass flow rate, driving amplitude, and measuring tube stiffness remain constant, The magnitude of this determines the magnitude of the Coriolis displacement, i.e., the magnitude of the mass flow measurement effect. The inventors noted that in typical single-phase flow applications, The value of ω is close to 0 because the magnitude of Q is in the thousands, and in mass flow meters of related technologies... C The value is ω D 2-3 times, and ω in the formula equals ω D .

[0088] So, when the operating frequency ω of the mass flow meter approaches ω C , i.e., ω D Approaching ω C hour, An increase means that, with other factors remaining constant, the mass flow measurement effect increases, and the signal-to-noise ratio of the mass flow meter also increases accordingly.

[0089] In view of this, the present application provides a mass flow meter that improves the mass flow measurement effect by making the first modal frequency ω1 and the second modal frequency ω2 of the measuring component satisfy: 0.8≤ω1 / ω2≤1.2, thereby making the first modal frequency close to the second modal frequency.

[0090] The inventors also discovered that if the characteristic frequency of the Coriolis mode is too close to the operating frequency, it will cause severe overlap between the two in the frequency domain. This makes it difficult for related filtering techniques to distinguish the signals, leading to a sharp drop in the signal-to-noise ratio (SNR), causing the target signal to be overwhelmed by noise and severely affecting the accuracy of mass flow measurement. Furthermore, mass flow meters also suffer from susceptibility to vibration interference and zero-point instability. Maintaining a SNR of more than 10 Hz between the characteristic frequency of the Coriolis mode and the operating frequency can improve the SNR and enhance the frequency domain distinguishability between the two frequencies.

[0091] By making the difference between the first mode frequency ω1 and the second mode frequency ω2 10Hz or more, it is possible to prevent the first mode frequency and the second mode frequency from overlapping too much in the frequency domain, thereby improving the distinction between the first mode frequency and the second mode frequency in the frequency domain. As a result, the signal-to-noise ratio of the mass flow meter can be effectively improved, thereby improving the zero-point stability of the mass flow meter.

[0092] The specific implementation of the mass flow meter provided in this application will be described in detail below with reference to the accompanying drawings.

[0093] Reference Figures 1 to 7 As shown, the mass flow meter provided in this application embodiment includes a measurement component 100. The measurement component 100 has a first modal frequency ω1 and a second modal frequency ω2, wherein the first modal frequency ω1 corresponds to the Coriolis mode of the measurement component 100, and the second modal frequency ω2 corresponds to the driving mode of the measurement component 100.

[0094] The first modal frequency ω1 and the second modal frequency ω2 satisfy the condition: 0.8 ≤ ω1 / ω2 ≤ 1.2. The mass flow meter provided in this application includes a measuring component 100. By setting the measuring component 100 to drive the measured fluid to vibrate, the Coriolis effect is induced in the measured fluid, thereby measuring the mass flow rate of the measured fluid through the Coriolis effect. Since the ratio of the first modal frequency to the second modal frequency of the measuring component 100 is between 0.8 and 1.2, the second modal frequency of the measuring component 100 is close to the first modal frequency of the measuring component 100, thereby improving the mass flow measurement effect of the measuring component 100 and thus improving the signal-to-noise ratio of the mass flow meter.

[0095] The first mode frequency ω1 and the second mode frequency ω2 satisfy: |ω1-ω2|≥10Hz and At least one of them, Because the absolute value of the difference between the first mode frequency and the second mode frequency is greater than or equal to 10Hz or 2%, it is to prevent excessive overlap between the operating frequency and the second mode frequency in the frequency domain, which would reduce the signal-to-noise ratio. Therefore, the mass flow meter provided in this application embodiment has a high signal-to-noise ratio and high zero-point stability.

[0096] In some embodiments, the measurement assembly 100 includes at least one measurement tube 110 and a stiffness enhancement unit 120, the measurement tube 110 being configured to allow the flow of a fluid to be measured. The stiffness enhancement unit 120 is connected to the measurement tube 110, thereby increasing the modal frequency of the driving mode of the measurement tube 110.

[0097] Understandably, the mass flow meter may also include a phase detection element 200 and an exciter 300. The exciter 300 drives the measuring tube 110 to vibrate. The measuring tube 110 is used to allow the fluid to be measured to flow. When the fluid to be measured flows in the vibrating measuring tube 110, the phase detection element 200 can detect the phase at the inlet end and the phase at the outlet end of the measuring tube 110. By obtaining the phase difference between the inlet and outlet ends of the measuring tube 110, the mass flow rate of the fluid to be measured can be calculated using the Coriolis effect. The operating frequency of the exciter 300 is equal to or approximately equal to the second modal frequency of the measuring component 100.

[0098] The exciter 300 can be connected to the middle of the extending direction of the measuring tube 110. The measuring tube 110 can be a straight tube, a micro-bend tube, a large bend tube, an Ω-shaped tube, a δ-shaped tube, etc. This application embodiment does not limit this.

[0099] Since the measuring tube 110 is provided with a stiffness enhancement unit 120, the stiffness enhancement unit 120 and the measuring tube 110 constitute the measuring component 100. The stiffness enhancement unit 120 can increase the second mode frequency of the measuring component 100, thereby making the second mode frequency close to the first mode frequency, that is, 0.8≤ω1 / ω2≤1.2. In this way, the mass flow measurement effect of the mass flow meter can be improved, thereby improving the signal-to-noise ratio of the mass flow meter.

[0100] Meanwhile, to prevent severe overlap between the first and second mode frequencies in the frequency domain, which could affect the signal-to-noise ratio, the absolute value of the difference between the first and second mode frequencies can be greater than or equal to 10Hz, i.e., |ω1-ω2|≥10Hz. Alternatively, the absolute value of the difference between the first and second mode frequencies can be greater than or equal to 2%, i.e., in,

[0101] This ensures the distinction between the operating frequency and the second mode frequency in the frequency domain and prevents a decrease in the signal-to-noise ratio due to severe overlap between the two. Therefore, the measurement component 100 of this embodiment improves the signal-to-noise ratio of the mass flow meter, thereby improving the zero-point stability of the mass flow meter, and ultimately enhancing the accuracy and repeatability of the mass flow meter.

[0102] In one possible implementation, the measuring tube 110 has a third modal frequency ω3, which corresponds to the Coriolis mode of the measuring tube 110. The first modal frequency ω1 and the third modal frequency ω3 satisfy: -5% ≤ (ω1-ω3) / ω1 ≤ 5%.

[0103] In other words, before the stiffness enhancement unit 120 is provided on the measuring tube 110, the measuring tube 110 has a third modal frequency corresponding to the Coriolis mode. After the stiffness enhancement unit 120 is provided on the measuring tube 110, the measuring component 100 has a first modal frequency corresponding to the Coriolis mode. Providing the stiffness enhancement unit 120 on the measuring tube 110 can significantly improve the second modal frequency of the measuring component 100, while having a small impact on the first modal frequency of the measuring component 100. Moreover, the impact of providing the stiffness enhancement unit 120 on the first modal frequency of the measuring component 100 is less than or equal to 5%.

[0104] In some embodiments, the first modal frequency ω1 and the third modal frequency ω3 satisfy: -1% ≤ (ω1-ω3) / ω1 ≤ 1%. That is, the influence of the stiffness enhancement unit 120 on the first modal frequency of the measuring component 100 can be very small.

[0105] In one possible implementation, the measuring tube has a fourth modal frequency ω4, which corresponds to the driving mode of the measuring tube. The second modal frequency ω2 and the fourth modal frequency ω4 satisfy the following:

[0106] (ω2-ω4) / ω2≥50%.

[0107] In other words, before the stiffness enhancement unit 120 is provided on the measuring tube 110, the measuring tube 110 has a fourth modal frequency corresponding to the driving mode. After the stiffness enhancement unit 120 is provided on the measuring tube 110, the measuring component 100 has a second modal frequency corresponding to the driving mode. Providing the stiffness enhancement unit 121 on the measuring tube 110 can significantly improve the second modal frequency of the measuring component 100, and providing the stiffness enhancement unit 120 can increase the second modal frequency of the measuring component 100 by more than 50% relative to the fourth modal frequency of the measuring tube.

[0108] In some embodiments, the thickness direction of the stiffness enhancement unit 120 is consistent with the extension direction of the measuring tube 110, and the midpoint of the stiffness enhancement unit 120 in its thickness direction is located in the middle of the extension direction of the measuring tube 110.

[0109] This is because both the driving mode and the Coriolis mode of a mass flow meter can be based on the two lowest-frequency natural modes, namely the first symmetric mode and the first antisymmetric mode. In related technologies, some mass flow meters use the first symmetric mode as the driving mode, while others use the first antisymmetric mode as the excitation mode. The ratio of the resonant frequencies of these two modes is generally between 2 and 3, with the first antisymmetric mode frequency being higher than that of the first symmetric mode.

[0110] The mass flow meter of this embodiment can use the first symmetric mode as the driving mode. The maximum vibration displacement occurs at the exciter 300 located in the middle of the measuring tube 110, while in the Coriolis mode, this displacement is zero. Simultaneously, the inventors also noted that changing the modal stiffness of the driving mode of the measuring component 100 by changing its stiffness is more effective than changing the mass of the measuring component 100. Therefore, the exciter 300 can be positioned in the middle of the measuring tube 110, and the stiffness enhancement unit 120 can be disposed within the measuring tube 110 to significantly improve the stiffness of the measuring component 100, thereby significantly increasing the second modal frequency of the measuring component 100.

[0111] Wherein, along the extension direction of the measuring tube 110, the extension length of the measuring tube 110 is L, the midpoint of the measuring tube 110 is at L / 2, and the middle part of the extension direction of the measuring tube 110 is (1 / 2±20%)*L. That is to say, the middle part of the measuring tube 110 can be understood as the midpoint of the measuring tube 110 being offset by 20% before and after the midpoint of the midpoint of the measuring tube 110 in the extension direction. As long as the midpoint of the stiffness reinforcement unit 120 in the thickness direction is within this range, it can be considered that the midpoint of the stiffness reinforcement unit 120 in the thickness direction is located within the middle part of the extension direction of the measuring tube 110.

[0112] It should be understood that, regardless of the shape of the measuring tube 110, the center of the stiffness enhancement unit 120 in its thickness direction is always located in the middle of the extension direction of the measuring tube 110.

[0113] In some embodiments, the weight m1 of the stiffness enhancement unit 120 and the weight m2 of the measuring tube 110 satisfy the following condition: m1 ≤ 20% m2.

[0114] Understandably, the stiffness enhancement unit 120 needs to increase the stiffness of the measuring component 100 and prevent the ineffective mass of the measuring component 100 from being too large due to the stiffness enhancement unit 120. Therefore, the weight of the stiffness enhancement unit 120 needs to be less than or equal to 20% of the weight of the measuring tube 110 so that the stiffness enhancement unit 120 can significantly increase the stiffness of the measuring component 100 and minimize the ineffective mass of the measuring component 100.

[0115] For example, the weight m1 of the stiffness enhancement unit 120 and the weight m2 of the measuring tube 110 satisfy the condition that m1 ≤ 10% m2. By designing the structure of the stiffness enhancement unit 120, the mass of the stiffness enhancement unit 120 is reduced as much as possible while ensuring the stiffness requirements.

[0116] In some embodiments, the stiffness enhancement unit 120 is welded to the measuring tube 110. This arrangement allows the stiffness enhancement unit 120 to be reliably fixed to the outer wall of the measuring tube 110, thereby preventing the stiffness enhancement unit 120 from separating from the measuring tube 110 when it vibrates with the measuring tube 110.

[0117] Reference Figures 8 to 12 As shown, in one possible implementation, the stiffness enhancement unit 120 includes at least one stiffness enhancement element 121, or the stiffness enhancement unit 120 may also include two or more stiffness enhancement elements 121.

[0118] For example, when the stiffness enhancement unit 120 includes two stiffness enhancement members 121, referred to as the first stiffness enhancement member and the second stiffness enhancement member respectively, the first stiffness enhancement member and the second stiffness enhancement member are disposed on the same measuring tube 110, the first stiffness enhancement member and the second stiffness enhancement member are arranged along the extension direction of the measuring tube 110, the first stiffness enhancement member has a first midpoint in its own thickness direction, the second stiffness enhancement member has a second midpoint in its own thickness direction, and there is a third midpoint between the first midpoint and the second midpoint. In this case, the third midpoint can be considered as the midpoint of the stiffness enhancement unit 120. When the third midpoint is located in the middle of the extension direction of the measuring tube 110, the stiffness enhancement unit 120 can be considered to be disposed in the middle of the measuring tube 110.

[0119] Reference Figure 1 As shown, in some embodiments, the mass flow meter also includes a temperature sensing element 400, a support tube 500, and a housing 600, the housing 600 and the support tube 500 being connected to define a cavity between them.

[0120] For example, the housing 600 can be connected to the radial side of the support tube 500, and the inner wall of the housing 600 and part of the outer wall of the support tube 500 can jointly define a cavity. The inlet and outlet ends of the measuring tube 110 can be respectively inserted into the two ports of the support tube 500. The support tube 500 can provide support for the measuring tube 110, thereby improving the stability of the measuring tube 110 during measurement. The remaining part of the measuring tube 110 can extend from the support tube 500 into the cavity. The temperature sensing element 400 can be set on the outer wall of the measuring tube 110 and used to measure the temperature of the fluid being measured, so as to perform temperature compensation and correction, thereby improving the measurement accuracy of the mass flow meter.

[0121] The cavity is filled with gas. When there is a temperature difference between the fluid to be measured in the measuring tube 110 and the filling gas, a temperature gradient is formed along the extension direction of the stiffness reinforcement 121, resulting in a temperature difference between the effective average temperature of the stiffness reinforcement 121 and the temperature of the measuring tube 110. Since the temperature sensing element 400 is located on the outer wall of the measuring tube 110, it is necessary to minimize the temperature difference between the stiffness reinforcement 121 and the measuring tube 110 to achieve more accurate temperature compensation and improve the measurement accuracy of the mass flow meter.

[0122] In this embodiment, each stiffness reinforcement 121 has at least one contact surface 1211a, which contacts the outer wall of the measuring tube 110. The contact surface 1211a is a concave arc surface, and the diameter of the contact surface 1211a matches the outer diameter of the measuring tube 110.

[0123] In this way, the contact surface 1211a can make close contact with the outer wall of the measuring tube 110, which can increase the contact area between the stiffness reinforcement 121 and the measuring tube 110, thereby reducing the temperature difference between the stiffness reinforcement 121 and the measuring tube 110. Since the stiffness reinforcement 121 is located at the point of maximum vibration amplitude, the stress of the stiffness reinforcement 121 has a significant impact on the vibration. Reducing the temperature difference between the stiffness reinforcement 121 and the measuring tube 110 allows the temperature detection element 400 outside the measuring tube 110 to more accurately reflect the stress of the stiffness reinforcement 121, thereby improving the accuracy of temperature compensation.

[0124] Furthermore, compared to line contact, surface contact can reduce the contact stress between the stiffness reinforcement 121 and the measuring tube 110, thereby ensuring the long-term stability of the measuring assembly 100.

[0125] Reference Figure 2 , Figure 7 and Figure 12 As shown, in some embodiments, there is one measuring tube 110. The measuring tube 110, the support tube 500 and the housing 600 are arranged in sequence from the inside to the outside along the radial direction of the measuring tube 110. The stiffness reinforcement 121 includes a first connecting part 1211, a second connecting part 1212 and a third connecting part 1213. The contact surface 1211a is provided on the first connecting part 1211. One of the housing 600 and the support tube 500 is connected to the measuring tube 110 through the stiffness reinforcement 121.

[0126] In other words, when there is only one measuring tube 110, the stiffness reinforcement 121 can be bridged between the measuring tube 110 and the housing 600, or the stiffness reinforcement 121 can also be bridged between the support tube 500 and the measuring tube 110, thereby increasing the second modal frequency of the measuring component 100 through the stiffness reinforcement 121.

[0127] Reference Figure 3 , Figures 8 to 11 As shown, in some embodiments, the measuring assembly 100 includes at least one set of measuring tubes 110, each set of measuring tubes 110 including two measuring tubes 110 arranged side by side along its radial direction. A single stiffness reinforcement 121 connects the two measuring tubes 110 in each set of measuring tubes 110.

[0128] For example, the measuring assembly 100 may include a set of measuring tubes 110, each set of measuring tubes 110 including two measuring tubes 110. The two measuring tubes 110 extend in the same direction and vibrate at the same operating frequency, but their phases are opposite. In this case, one or more stiffness reinforcement members 121 can be bridged between the two measuring tubes 110 and located in the middle of the extension direction of the measuring tubes 110. In this way, the stiffness reinforcement members 121 can effectively increase the second modal frequency of the measuring assembly 100 and have little impact on the first modal frequency of the measuring assembly 100.

[0129] For example, the measuring assembly 100 may include two sets of measuring tubes 110, each set of measuring tubes 110 including two measuring tubes 110, that is, the measuring assembly 100 includes four measuring tubes 110. The four measuring tubes 110 extend in the same direction, and the two measuring tubes 110 in each set vibrate at the same operating frequency, but their phases are opposite. In this case, one or more stiffness enhancement members 121 can be bridged between the two measuring tubes 110 in each set of measuring tubes 110 and located in the middle of the extension direction of the measuring tubes 110. In this way, the stiffness enhancement unit 120 can effectively improve the second modal frequency of the measuring assembly 100 and have little impact on the first modal frequency of the measuring assembly 100.

[0130] Reference Figures 8 to 11 As shown, specifically, the stiffness enhancement component 121 includes two first connecting parts 1211 and a second connecting part 1212. The contact surface 1211a is disposed on the first connecting part 1211. The first connecting part 1211 is connected to the measuring tube 110 in a one-to-one correspondence. The second connecting part 1212 connects the two first connecting parts 1211.

[0131] In this way, a single stiffness reinforcement 121 can be bridged between the two measuring tubes 110 in each group of measuring tubes 110 to improve the second modal frequency of the measuring assembly 100. The first connecting portion 1211 can be welded to the measuring tube 110, thereby allowing the stiffness reinforcement 121 to be welded to the measuring tube 110.

[0132] Reference Figures 8 to 11 , Figure 13As shown, in some embodiments, the second connecting portion 1212 extends along an arc. Since the two measuring tubes 110 connected by a single stiffness reinforcement 121 will move closer or further apart during vibration, the second connecting portion 1212 bridging the two measuring tubes 110 needs to have a certain deformation capacity. The fact that the second connecting portion 1212 extends along an arc allows it to be stretched or shortened, thereby allowing it to deform with the vibration of the measuring tube 110, preventing the stiffness reinforcement 121 from hindering the vibration of the measuring tube 110.

[0133] In some embodiments, along the thickness direction of the stiffness reinforcement 121, the width of the first connecting portion 1211 is greater than or equal to the width of the second connecting portion 1212, so that the first connecting portion 1211 can quickly transfer temperature to reduce the temperature difference between the stiffness reinforcement 121 and the measuring tube, and the smaller width of the second connecting portion 1212 makes it easier to adjust the effective stiffness of the stiffness reinforcement 121 to meet the stiffness requirements of various mass flow meters.

[0134] like Figure 9 , Figure 10 As shown, the width of the first connecting portion 1211 is greater than the width of the second connecting portion 1212. For example... Figure 9 As shown, along the thickness direction of the stiffness reinforcement 121, an arc-shaped transition structure is provided at the connection between the first connecting portion 1211 and the second connecting portion 1212, and the arc-shaped transition structure extends outward along the width direction of the first connecting portion 1211. Figure 10 As shown, along the thickness direction of the stiffness reinforcement 121, a stepped structure is provided at the connection between the first connecting portion 1211 and the second connecting portion 1212, and the stepped structure extends outward along the width direction of the first connecting portion 1211. By making the width of the first connecting portion 1211 greater than the width of the second connecting portion 1212, the length or height of the second connecting portion 1212 can be reduced under the same stiffness requirements, thereby reducing the mass of the stiffness reinforcement 121.

[0135] like Figures 8 to 10 As shown, the thickness of the second connecting portion 1212 is uniformly distributed along the thickness direction of the vertical stiffness reinforcement 121; as Figure 11 As shown, in the thickness direction of the vertical stiffness reinforcement 121, the thickness of the second connecting portion 1212 gradually increases from the middle to both ends. Specifically, the thickness of the second connecting portion 1212 gradually increases from the middle to both ends. A uniform thickness distribution or a gradual increase from the middle to both ends of the second connecting portion 1212 better balances the stiffness of the stiffness reinforcement 121 and the structural stability.

[0136] like Figures 8 to 11As shown, the curvature of the inner arc surface of the second connecting part 1212 of the stiffness reinforcement 121 is greater than that of the contact surface, thereby reducing the volume of the stiffness reinforcement 121 and enabling the smaller stiffness reinforcement 121 to meet the stiffness requirements of the mass flow meter.

[0137] like Figures 8 to 11 As shown, at least a portion of the thickness of the first connecting portion 1211 is greater than or equal to the thickness of the second connecting portion 1212. For example... Figure 8 , Figure 10 , Figure 11 As shown, at least a portion of the thickness of the first connecting part 1211 is greater than the thickness of the second connecting part 1212, which can better adjust the position of the contact surface 1211a, ensure that the contact surface 1211a can better fit with the measuring tube 110, and improve the long-term stability of the measuring component 100.

[0138] In some specific embodiments, such as Figure 4 , Figure 5 , Figure 13 As shown, the two ends of the measuring tube 110 are connected to the support tube 500, and the middle part of the measuring tube 110 protrudes relative to the support tube 500. The stiffness reinforcement 121 is located outside the middle part of the measuring tube 110. The protruding direction of the middle part of the measuring tube 110 is defined as the height direction. The top of the second connecting part 1212 is higher than the top of the first connecting part 1211. At least part of the first connecting part 1211 is located between the two measuring tubes 110, thereby improving the structural stability of the stiffness reinforcement 121 and ensuring the stiffness requirements.

[0139] Reference Figures 13 to 16 As shown, in one possible implementation, the area S1 of the contact surface 1211a and the average cross-sectional area S2 of the second connecting portion 1212 on the reference plane satisfy: S1 / S2≥2. Wherein, each reference plane is perpendicular to the extending direction of the second connecting portion 1212 at its corresponding position on the reference plane.

[0140] In other words, the average cross-sectional area S2 of the second connecting part 1212 on each reference plane can be understood as the average cross-sectional area of ​​the stiffening reinforcement 121 bridging the two measuring tubes 110 at each position; or, the average cross-sectional area S2 of the second connecting part 1212 on each reference plane can be understood as the average cross-sectional area of ​​the stiffening reinforcement 121 bridging the measuring tube 110 and the support tube 500 at each position; or, the average cross-sectional area S2 of the second connecting part 1212 on each reference plane can be understood as the average cross-sectional area of ​​the stiffening reinforcement 121 bridging the measuring tube 110 and the housing 600 at each position. For details, please refer to... Figure 14 and Figure 16 ,because Figure 14 and Figure 16The cross-section of the second connecting part 1212 is uniformly distributed, so the size of the cross-section 1212a shown in the figure is the average cross-sectional area S2 of the second connecting part 1212 on each reference plane.

[0141] Thus, when the ratio of the area S1 of the contact surface 1211a to the average cross-sectional area S2 of the second connecting portion 1212 on each reference plane is greater than or equal to 2, the contact area between the stiffness reinforcement 121 and the measuring tube 110 can be effectively increased, thereby effectively reducing the temperature difference between the stiffness reinforcement 121 and the measuring tube 110, and thus improving the accuracy of temperature compensation, thereby improving the accuracy of the mass flow meter. Furthermore, when the ratio of the area S1 of the contact surface 1211a to the average cross-sectional area S2 of the second connecting portion 1212 on each reference plane is greater than or equal to 2, the contact stress between the stiffness reinforcement 121 and the measuring tube 110 can be effectively reduced, preventing damage to the stiffness reinforcement 121 or the measuring tube 110 during vibration, thereby ensuring the long-term stability of the measuring assembly 100.

[0142] Furthermore, when S1 and S2 satisfy S1 / S2≥2, the stiffness of the second connection 1212 can be effectively controlled. While reducing the temperature difference, the modal frequency of the driving mode of the stiffness enhancement member 121 can be effectively increased, thereby increasing the second modal frequency of the measuring component 100.

[0143] For example, the area S1 of the contact surface 1211a and the projected area S2 of the stiffening reinforcement 121 on the reference plane satisfy: S1 / S2≥4. This increases the area S1 of the contact surface 1211a and decreases the average cross-sectional area S2 of the stiffening reinforcement 121 on each reference plane, thereby effectively reducing the temperature difference between the stiffening reinforcement 121 and the measuring tube 110, allowing the temperature of the stiffening reinforcement 121 to quickly approach the temperature of the measuring tube 110, and improving the accuracy of temperature compensation.

[0144] The following comparison is made between the mass flow meters in the related art and the mass flow meters in the embodiments of this application.

[0145] Mass flow meters of related technologies 170 421.9 The mass flow meter in this embodiment 406 422

[0146] As can be seen from the table above, the modal frequency of the driving mode of the mass flow meter in this embodiment is significantly improved, and the difference between the modal frequency of the driving mode and the modal frequency of the Coriolis mode of the mass flow meter in this embodiment is more than 10 Hz.

[0147] air pressure 1.02 bara 1.02 bara 1.03bara Mass flow meter repeatability % of related technologies 0.551921626 0.185111236 0.094277995 The repeatability % of the mass flow meter in this embodiment 0.159949594 0.060514131 0.040613607

[0148] As can be seen from the table above, the mass flow meter in this embodiment exhibits high repeatability when measuring gas under different air flow rates and air pressure conditions.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A mass flow meter characterized by, include: A measurement component having a first modal frequency ω1 and a second modal frequency ω2, wherein the first modal frequency ω1 and the second modal frequency ω2 satisfy: 0.8 ≤ ω1 / ω2 ≤ 1.2; Wherein, the first modal frequency ω1 corresponds to the Coriolis mode of the measurement component, and the second modal frequency ω2 corresponds to the driving mode of the measurement component.

2. The mass flow meter of claim 1, wherein, The first modal frequency ω1 and the second modal frequency ω2 satisfy: |ω1-ω2|≥10 Hz, or at least one of 3. The mass flow meter of claim 1, wherein, The measuring component includes: at least one measuring tube configured to allow the flow of a measured fluid, the measuring tube having a third modal frequency ω3, the third modal frequency ω3 corresponding to the Coriolis mode of the measuring tube, and the first modal frequency ω1 and the third modal frequency ω3 satisfying: -5%≤(ω1-ω3) / ω3≤5%.

4. The mass flow meter of claim 3, wherein, The measuring tube has a fourth mode frequency ω4, which corresponds to the driving mode of the measuring tube. The second mode frequency ω2 and the fourth mode frequency ω4 satisfy the following: (ω2-ω4) / ω2≥50%.

5. The mass flow meter of claim 3 or 4, wherein, The measuring assembly also includes a stiffness enhancement unit, which is connected to the measuring tube.

6. The mass flow meter of claim 5, wherein, The thickness direction of the stiffness enhancement unit is consistent with the extension direction of the measuring tube, and the midpoint of the stiffness enhancement unit in its thickness direction is located inside the middle of the extension direction of the measuring tube. Wherein, along the extension direction of the measuring tube, the extension length of the measuring tube is L, the midpoint of the measuring tube is at L / 2, and the middle part of the extension direction of the measuring tube is (1 / 2±20%)*L.

7. The mass flow meter of claim 5, wherein, It also includes a housing and a support tube, with the stiffness-enhancing unit bridging the measuring tube and the housing; Alternatively, the stiffness enhancement unit is bridged between the measuring tube and the support tube; Alternatively, the stiffness-enhancing unit is bridged between the two measuring tubes.

8. The mass flow meter of claim 7, wherein, The stiffness enhancement unit includes at least one stiffness enhancement component, which includes two first connecting parts and a second connecting part, wherein the first connecting parts are connected to the measuring tube in a one-to-one correspondence. Alternatively, the stiffness reinforcement may include a first connecting part, a second connecting part, and a third connecting part connected in sequence, wherein the first connecting part is connected to the measuring tube, and one of the housing and the support tube is connected to the third connecting part.

9. The mass flow meter of claim 8, wherein, The first connecting part is provided with a contact surface, which contacts the outer wall of the measuring tube; The contact surface is a concave arc surface, and the diameter of the contact surface matches the outer diameter of the measuring tube.

10. The mass flow meter of claim 9, wherein, The area S1 of the contact surface and the average cross-sectional area S2 of the second connecting part on each reference plane satisfy: S1 / S2≥2; Wherein, each of the reference planes is perpendicular to the extension direction of the second connecting portion at its respective position.

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