Mass flow meter and mass flow controller

Abstract

The utility model relates to the technical field of flow meters, and provides a mass flow meter and a mass flow controller. The mass flow meter comprises a main pipeline with a main flow channel and a flow sensor; the flow sensor comprises a first pipeline, a first upstream thermistor, a first downstream thermistor, a second pipeline, a second upstream thermistor and a second downstream thermistor, the first pipeline comprises a first measuring pipe section, and the first upstream thermistor and the first downstream thermistor are arranged on the first measuring pipe section; the second pipeline comprises a second measuring pipe section, and a second upstream thermistor and a second downstream thermistor are arranged on the second measuring pipe section; the first measuring pipe section and the second measuring pipe section are arranged in parallel, and the arrangement direction of the first upstream thermistor and the first downstream thermistor is opposite to the arrangement direction of the second upstream thermistor and the second downstream thermistor. By means of the design, the mass flow meter can obtain a real flow value in any installation posture, and the problem that the flow measurement precision is poor is solved.

Description

Technical Field

[0001] This application relates to the technical field of flow meters, and particularly to a mass flow meter and a mass flow controller. Background Art

[0002] A mass flow controller (MFC), as an instrument for measuring and controlling fluid flow, is widely used in semiconductor manufacturing, biopharmaceuticals, environmental monitoring, and other fields that require precise control of fluid flow. Its working principle is based on the heat change caused by the fluid passing through the sensor. The size of the fluid flow directly affects the sensor temperature. By monitoring this temperature change, the real-time flow rate of the fluid can be calculated.

[0003] The flow sensor is a key component of the mass flow controller. It generally consists of an upstream thermistor, a downstream thermistor, a capillary tube, and a control circuit, etc. Its principle is to heat the upstream thermistor and the downstream thermistor by applying current. When there is no fluid flow in the capillary tube, the heating powers of the two thermistors remain balanced; when there is fluid flow in the capillary tube, the heat exchange between the fluid and the thermistors will cause the heating powers of the two thermistors to change, and this change increases with the increase of the fluid mass flow rate. By measuring the voltage on the thermistor and through the conversion of the control circuit, the fluid flow rate can be converted into an electrical signal, thus achieving precise measurement of the mass flow.

[0004] As Figure 1 shown, when the measuring pipe section 21 of the flow sensor 20 is perpendicular to the direction of gravity, the fluid in the measuring pipe section 21 of the flow sensor 20 is heated by the thermistor 22 to a temperature higher than that of the fluid in the main flow path 31 of the main pipeline 30. Due to the temperature difference, the density of the fluid in the measuring pipe section 21 of the flow sensor 20 is less than the density of the fluid in the main flow path 31 of the main pipeline 30. Therefore, when the main valve 32 of the main pipeline 30 is in the closed position, a density gradient will form and be maintained by gravity, where the fluid with a lower temperature and a larger density is in the main flow path 31, and the fluid with a higher temperature and a smaller density is in the flow sensor 20, and no deviation occurs.

[0005] As Figure 2As shown in the figure, when the measuring pipe section 21 of the flow sensor 20 is parallel to the direction of gravity, the fluid in the measuring pipe section 21 of the flow sensor 20 will be heated by the thermistor 22 to a temperature higher than that of the fluid in the main flow path 31. The fluid with a higher temperature and lower density in the measuring pipe section 21 of the flow sensor 20 rises and enters the main flow path 31 from the outlet of the flow sensor 20, and this fluid is cooled to form a downward air flow; when the main valve 32 of the main pipeline 30 is in the closed position, the downward air flow enters the flow sensor 20 through the inlet of the flow sensor 20 and is heated by the thermistor 22, thus forming a circulation loop. The phenomenon of spontaneous circulation movement of liquid or gas caused by gravity and temperature difference as described above is called the thermosiphon phenomenon.

[0006] Due to the existence of the thermosiphon phenomenon, the electrical signal of the flow sensor will be detected, calculated and processed by the acquisition circuit to determine that there is flow generation, resulting in flow measurement error and affecting the flow measurement accuracy of the mass flow controller. Utility Model Content

[0007] In view of this, the embodiments of the present application provide a mass flowmeter and a mass flow controller to solve the problem of poor flow measurement accuracy.

[0008] A first aspect of the present application provides a mass flowmeter, including a main pipeline and a flow sensor. The main pipeline has a main flow path, and the flow sensor is installed on the main pipeline; the flow sensor includes a first pipeline, a first upstream thermistor, a first downstream thermistor, a second pipeline, a second upstream thermistor and a second downstream thermistor. The two ends of the first pipeline are respectively connected to the upstream and downstream of the main flow path. The first pipeline includes a first measuring pipe section, and the first upstream thermistor and the first downstream thermistor are arranged on the first measuring pipe section; the two ends of the second pipeline are respectively connected to the upstream and downstream of the main flow path. The second pipeline includes a second measuring pipe section, and the second upstream thermistor and the second downstream thermistor are arranged on the second measuring pipe section; wherein, the first measuring pipe section and the second measuring pipe section are arranged in parallel and have the same cross-sectional area, and the arrangement directions of the first upstream thermistor and the first downstream thermistor are opposite to the arrangement directions of the second upstream thermistor and the second downstream thermistor.

[0009] The beneficial effects of the mass flowmeter provided by the embodiments of the present application are as follows: when in use, the fluid in the main flow path enters the first pipeline and the second pipeline respectively. Since the first measurement pipe section of the first pipeline and the second measurement pipe section of the second pipeline are arranged in parallel and have the same cross-sectional area, and the arrangement directions of the first upstream thermistor and the first downstream thermistor on the first measurement pipe section are opposite to the arrangement directions of the second upstream thermistor and the second downstream thermistor on the second measurement pipe section, therefore, after the measurement signals fed back by the first pipeline and the second pipeline are added, the error signals generated by the thermosiphon effect in the two measurement signals can just cancel each other out. If the ratio of the flow rate of the main pipeline to the sum of the flow rates of the two pipelines is the set split ratio, then the sum of the flow rate values measured by the first pipeline and the second pipeline is the true flow rate value; if the ratio of the flow rate of the main pipeline to the flow rate of one of the pipelines is the set split ratio, then half of the sum of the flow rate values measured by the first pipeline and the second pipeline is the true flow rate value. Through the above design, the mass flowmeter can obtain the true flow rate value in any installation posture, solving the problem of poor flow measurement accuracy.

[0010] In some embodiments, both the first measurement pipe section and the second measurement pipe section are perpendicular to the axis direction of the main flow path; or, both the first measurement pipe section and the second measurement pipe section are parallel to the axis direction of the main flow path.

[0011] In some embodiments, the main pipeline is provided with a first upstream channel, a first downstream channel, a second upstream channel and a second downstream channel. The first pipeline connects the upstream and downstream of the main flow path through the first upstream channel and the first downstream channel, and the second pipeline connects the upstream and downstream of the main flow path through the second upstream channel and the second downstream channel; the inlets of the first upstream channel and the second upstream channel are arranged close to each other, and the outlets of the first downstream channel and the second downstream channel are arranged close to each other.

[0012] In some embodiments, the first pipeline further includes a first upstream pipe section and a first downstream pipe section. The first measurement pipe section is connected between the first upstream pipe section and the first downstream pipe section. The first upstream pipe section is connected to the first upstream channel, and the first downstream pipe section is connected to the first downstream channel.

[0013] In some embodiments, the second pipeline further includes a second upstream pipe section and a second downstream pipe section. The second measurement pipe section is connected between the second upstream pipe section and the second downstream pipe section. The second upstream pipe section is connected to the second upstream channel, and the second downstream pipe section is connected to the second downstream channel.

[0014] In some embodiments, the first pipeline and the second pipeline have the same structure.

[0015] In some embodiments, the mass flowmeter further includes a laminar flow element disposed in the main flow path.

[0016] In some embodiments, at least one of the first upstream thermistor, the first downstream thermistor, the second upstream thermistor, and the second downstream thermistor is a winding structure.

[0017] In some embodiments, the first pipeline and / or the second pipeline is a capillary tube.

[0018] A second aspect of the present application provides a mass flow controller, which includes a main valve and the mass flowmeter as described in the first aspect. The main valve is installed at the fluid outlet of the mass flowmeter.

[0019] This mass flow controller adopts any one or more embodiments of the above-mentioned mass flowmeter, and thus has the beneficial effects of the above embodiments, which will not be elaborated here one by one.

[0020] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically given below. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of conventional technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 is a schematic structural diagram of the first installation posture of the existing mass flow controller;

[0023] Figure 2 is a schematic structural diagram of the second installation posture of the existing mass flow controller;

[0024] Figure 3 is a schematic structural diagram of the first installation posture of the mass flowmeter provided by the embodiment of the present application;

[0025] Figure 4 is a schematic structural diagram of the second installation posture of the mass flowmeter provided by the embodiment of the present application;

[0026] Figure 5 is Figure 4 a schematic structural diagram of the flow sensor in

[0027] Figure 6 It is a schematic structural diagram of a mass flow controller provided by an embodiment of the present application.

[0028] The meanings of the marks in the figure are as follows:

[0029] 10. Mass flowmeter;

[0030] 11. Main pipeline; 111. Main flow channel; 112. Fluid inlet; 113. Fluid outlet; 114. First upstream channel; 115. First downstream channel; 116. Second upstream channel; 117. Second downstream channel;

[0031] 12. Flow sensor; 121. First pipeline; 1211. First upstream pipe section; 1212. First measurement pipe section; 1213. First downstream pipe section; 122. First upstream thermistor; 123. First downstream thermistor; 124. Second pipeline; 1241. Second upstream pipe section; 1242. Second measurement pipe section; 1243. Second downstream pipe section; 125. Second upstream thermistor; 126. Second downstream thermistor;

[0032] 13. Laminar flow element;

[0033] 14. Main valve;

[0034] 20. Flow sensor; 21. Measurement pipe section; 22. Thermistor;

[0035] 30. Main pipeline; 31. Main flow channel; 32. Main valve;

[0036] 100. Mass flow controller. Detailed implementation manners

[0037] Hereinafter, embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, and thus are only examples and should not be used to limit the protection scope of the present application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0039] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0040] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] In the description of the embodiments of the present application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after.

[0042] In the description of the embodiments of the present application, the term "a plurality of" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0043] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0044] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0045] The thermosiphon phenomenon refers to the phenomenon of spontaneous circulation of liquids or gases caused by gravity and temperature differences in thermal flow sensors. When the flow sensor is in a vertical or inclined position, the temperature difference between the capillary of the flow sensor and the main flow path of the main pipeline will generate natural convection, resulting in the self-circulation of the fluid in the capillary and the main flow path. This phenomenon may affect the measurement accuracy of the flow sensor. The specific mechanism is as follows:

[0046] Temperature difference generates buoyancy: The heating element of the flow sensor will raise the temperature of the adjacent fluid. The fluid with increased temperature has a lower density, generating an upward buoyancy force.

[0047] Natural convection: Due to the buoyancy force, the hot fluid will rise and the cold fluid will sink, forming a natural convection cycle. This convection may not be consistent with the flow direction of the actual fluid being measured, thus introducing errors.

[0048] Affect measurement accuracy: This natural convection will interfere with the normal operation of the flow sensor, making the temperature difference detected by the flow sensor not completely caused by the actual flow rate, thereby affecting the measurement accuracy.

[0049] The first aspect of the present application proposes a mass flowmeter. Please refer to Figure 4 and Figure 5 simultaneously. The mass flowmeter 10 includes a main pipeline 11 and a flow sensor 12. The main pipeline 11 has a main flow path 111, and the flow sensor 12 is installed on the main pipeline 11; the flow sensor 12 includes a first pipeline 121, a first upstream thermistor 122, a first downstream thermistor 123, a second pipeline 124, a second upstream thermistor 125, and a second downstream thermistor 126. The two ends of the first pipeline 121 are respectively connected to the upstream and downstream of the main flow path 111. The first pipeline 121 includes a first measurement pipe section 1212, and the first upstream thermistor 122 and the first downstream thermistor 123 are arranged on the first measurement pipe section 1212; the two ends of the second pipeline 124 are respectively connected to the upstream and downstream of the main flow path 111. The second pipeline 124 includes a second measurement pipe section 1242, and the second upstream thermistor 125 and the second downstream thermistor 126 are arranged on the second measurement pipe section 1242; wherein, the first measurement pipe section 1212 and the second measurement pipe section 1242 are arranged in parallel and have the same cross-sectional area, and the arrangement directions of the first upstream thermistor 122 and the first downstream thermistor 123 are opposite to the arrangement directions of the second upstream thermistor 125 and the second downstream thermistor 126.

[0050] The main pipeline 11 has a main flow path 111. The main pipeline 11 is respectively provided with a fluid inlet 112 and a fluid outlet 113 at the axial two ends of the main flow path 111. The fluid inlet 112 and the fluid outlet 113 are both communicated with the main flow path 111. The fluid flows into the main flow path 111 through the fluid inlet 112 and flows out from the fluid outlet 113.

[0051] The flow sensor 12 measures the flow rate of the fluid when the fluid flows through the main flow path 111. Herein, the manner in which the flow sensor 12 is installed on the main pipeline 11 is not limited in this application. For example, the flow sensor 12 can be fixedly welded on the main pipeline 11, or the flow sensor 12 can be fixed on the main pipeline 11 through fasteners.

[0052] Both ends of the first pipeline 121 are respectively connected to the upstream and downstream of the main flow path 111, that is, the first end of the first pipeline 121 is connected to the upstream of the main flow path 111, and the second end of the first pipeline 121 is connected to the downstream of the main flow path 111; it can be understood that the first end of the first pipeline 121 is arranged close to the fluid inlet 112, and the second end of the first pipeline 121 is arranged close to the fluid outlet 113. Wherein, the fluid entering the main flow path 111 can flow in from the first end of the first pipeline 121 and flow out from the second end of the first pipeline 121.

[0053] The first pipeline 121 includes a first measurement pipe section 1212, and a first upstream thermistor 122 and a first downstream thermistor 123 are arranged on the first measurement pipe section 1212; wherein, when the fluid flows in the first measurement pipe section 1212, it first passes through the first upstream thermistor 122 and then passes through the first downstream thermistor 123. When the fluid flows through the first measurement pipe section 1212 of the first pipeline 121, the first upstream thermistor 122 and the first downstream thermistor 123 can feedback measurement signals, and the measurement signals are converted into the flow rate value of the main flow path 111 through the acquisition circuit at the rear end.

[0054] Both ends of the second pipeline 124 are respectively connected to the upstream and downstream of the main flow path 111, that is, the first end of the second pipeline 124 is connected to the upstream of the main flow path 111, and the second end of the second pipeline 124 is connected to the downstream of the main flow path 111; it can be understood that the first end of the second pipeline 124 is arranged close to the fluid inlet 112, and the second end of the second pipeline 124 is arranged close to the fluid outlet 113. Wherein, the fluid entering the main flow path 111 can flow in from the first end of the second pipeline 124 and flow out from the second end of the second pipeline 124.

[0055] The second pipeline 124 includes a second measurement pipe section 1242, and a second upstream thermistor 125 and a second downstream thermistor 126 are arranged on the second measurement pipe section 1242; wherein, when the fluid flows in the second measurement pipe section 1242, it first passes through the second upstream thermistor 125 and then passes through the second downstream thermistor 126. When the fluid flows through the second measurement pipe section 1242 of the second pipeline 124, the second upstream thermistor 125 and the second downstream thermistor 126 can feedback measurement signals, and the measurement signals are converted into the flow rate value of the main flow path 111 through the acquisition circuit at the rear end.

[0056] The first measurement pipe section 1212 and the second measurement pipe section 1242 are arranged in parallel. It can be understood that the two measurement pipe sections can be absolutely parallel or approximately parallel.

[0057] Among them, the cross-sectional areas of the first measurement pipe section 1212 and the second measurement pipe section 1242 are the same, that is, the flow rates of the first measurement pipe section 1212 and the second measurement pipe section 1242 are the same when the fluid flows through. Optionally, the cross-sectional shapes of the first measurement pipe section 1212 and the second measurement pipe section 1242 are the same. For example, the cross-sectional shapes of both are circular and have the same diameter.

[0058] The arrangement directions of the first upstream thermistor 122 and the first downstream thermistor 123 are opposite to those of the second upstream thermistor 125 and the second downstream thermistor 126. As Figure 5 shown, the first upstream thermistor 122 is arranged in alignment with the second downstream thermistor 126, and the first downstream thermistor 123 is arranged in alignment with the second upstream thermistor 125.

[0059] Among them, the first upstream thermistor 122 and the second upstream thermistor 125 are the same, and the first downstream thermistor 123 and the second downstream thermistor 126 are the same, so that the error signals generated by the thermosiphon effect in the two measurement signals can be exactly cancelled out.

[0060] As Figure 3 shown, both the first measurement pipe section 1212 and the second measurement pipe section 1242 are perpendicular to the gravity direction g. The hot fluid rises from both ends of the first measurement pipe section 1212 and is inside the first measurement pipe section 1212, and rises from both ends of the second measurement pipe section 1242 and is inside the second measurement pipe section 1242. Therefore, no thermosiphon effect will occur in this installation posture. As Figure 5As shown, taking the case where the first measuring pipe section 1212 and the second measuring pipe section 1242 are both parallel or approximately parallel to the gravity direction g as an example, the fluid in the main flow channel 111 enters the first pipeline 121 and the second pipeline 124 respectively. Since the first measuring pipe section 1212 of the first pipeline 121 and the second measuring pipe section 1242 of the second pipeline 124 are arranged in parallel and have the same cross-sectional area, and the arrangement directions of the first upstream thermistor 122 and the first downstream thermistor 123 on the first measuring pipe section 1212 are opposite to the arrangement directions of the second upstream thermistor 125 and the second downstream thermistor 126 on the second measuring pipe section 1242, therefore, after the measurement signals fed back by the first pipeline 121 and the second pipeline 124 are added, the error signals generated by the thermosiphon effect in the two measurement signals can just cancel each other out. If the ratio of the flow rate of the main pipeline 11 to the sum of the flow rates of the two pipelines is the set split ratio, then the sum of the flow rate values measured by the first pipeline 121 and the second pipeline 124 is the true flow rate value; if the ratio of the flow rate of the main pipeline 11 to the flow rate of one of the pipelines is the set split ratio, then half of the sum of the flow rate values measured by the first pipeline 121 and the second pipeline 124 is the true flow rate value. Through the above design, the mass flowmeter 10 can obtain the true flow rate value in any installation posture, solving the problem of poor flow measurement accuracy.

[0061] Please also refer to Figure 4 and Figure 5 , in some embodiments, the first measuring pipe section 1212 and the second measuring pipe section 1242 are both perpendicular to the axis direction of the main flow channel 111. Among them, the axis direction of the main flow channel 111 is the flow direction of the fluid in the main flow channel 111.

[0062] By adopting the above technical solution, the lengths of the first upstream channel 114, the first downstream channel 115, the second upstream channel 116, and the second downstream channel 117 provided on the main pipeline 11 are all not long, which is beneficial to processing the above channels on the main pipeline 11.

[0063] In other embodiments, the first measuring pipe section 1212 and the second measuring pipe section 1242 are both parallel to the axis direction of the main flow channel 111. At this time, the first upstream channel 114 and the first downstream channel 115 are shorter, and the second upstream channel 116 and the second downstream channel 117 are longer; or, the first upstream channel 114 and the first downstream channel 115 are longer, and the second upstream channel 116 and the second downstream channel 117 are shorter.

[0064] Please refer to Figure 4, in some embodiments, a first upstream channel 114, a first downstream channel 115, a second upstream channel 116, and a second downstream channel 117 are provided on the main pipeline 11. The first pipeline 121 is connected to the upstream and downstream of the main flow channel 111 through the first upstream channel 114 and the first downstream channel 115, and the second pipeline 124 is connected to the upstream and downstream of the main flow channel 111 through the second upstream channel 116 and the second downstream channel 117; the inlets of the first upstream channel 114 and the second upstream channel 116 are arranged close to each other, and the outlets of the first downstream channel 115 and the second downstream channel 117 are arranged close to each other.

[0065] Optionally, both the first measuring pipe section 1212 and the second measuring pipe section 1242 are perpendicular to the axis direction of the main flow channel 111. At this time, the first upstream channel 114, the first downstream channel 115, the second upstream channel 116, and the second downstream channel 117 are all inclined channels. Of course, both the first measuring pipe section 1212 and the second measuring pipe section 1242 can be parallel to the axis direction of the main flow channel 111. At this time, the first upstream channel 114 and the first downstream channel 115 can be straight channels, and the second upstream channel 116 and the second downstream channel 117 are inclined channels; or, the first upstream channel 114 and the first downstream channel 115 are inclined channels, and the second upstream channel 116 and the second downstream channel 117 can be straight channels.

[0066] Wherein, the inlets of the first upstream channel 114 and the second upstream channel 116 being arranged close to each other means that the inlets of the first upstream channel 114 and the second upstream channel 116 are relatively close; the outlets of the first downstream channel 115 and the second downstream channel 117 being arranged close to each other means that the outlets of the first downstream channel 115 and the second downstream channel 117 are relatively close.

[0067] Since the inlets of the first upstream channel 114 and the second upstream channel 116 are arranged close to each other, and the outlets of the first downstream channel 115 and the second downstream channel 117 are arranged close to each other, therefore, the thermal effects generated by the first pipeline 121 and the second pipeline 124 are closer. Therefore, after the error signals generated by the two pipelines due to the thermosiphon effect are cancelled out, the measured value is closer to the true value.

[0068] In other embodiments, the inlets of the first upstream channel 114 and the second upstream channel 116 can also be arranged adjacent to each other, or the first upstream channel 114 and the second upstream channel 116 share an inlet.

[0069] In other embodiments, the outlets of the first downstream channel 115 and the second downstream channel 117 can also be arranged adjacent to each other, or the first downstream channel 115 and the second downstream channel 117 share an outlet.

[0070] Please refer toFigure 4 and Figure 5 , in some embodiments, the first pipeline 121 further includes a first upstream pipe section 1211 and a first downstream pipe section 1213. The first measurement pipe section 1212 is connected between the first upstream pipe section 1211 and the first downstream pipe section 1213. The first upstream pipe section 1211 is connected to the first upstream channel 114, and the first downstream pipe section 1213 is connected to the first downstream channel 115.

[0071] Optionally, both the first upstream pipe section 1211 and the first downstream pipe section 1213 extend along the radial direction of the main flow channel 111. It can be understood that the first upstream pipe section 1211 and the first downstream pipe section 1213 can be arranged in parallel, that is, the angles between the first upstream pipe section 1211 and the first measurement pipe section 1212 and between the first downstream pipe section 1213 and the first measurement pipe section 1212 are the same. For example, they are both 90°; or, the angles between the first upstream pipe section 1211 and the first measurement pipe section 1212 and between the first downstream pipe section 1213 and the first measurement pipe section 1212 can both be acute angles; or, the angles between the first upstream pipe section 1211 and the first measurement pipe section 1212 and between the first downstream pipe section 1213 and the first measurement pipe section 1212 can both be obtuse angles.

[0072] By adopting the above technical solution, the structure of the first pipeline 121 is simplified, which is beneficial to the flow of fluid in the first pipeline 121.

[0073] In some embodiments, the second pipeline 124 further includes a second upstream pipe section 1241 and a second downstream pipe section 1243. The second measurement pipe section 1242 is connected between the second upstream pipe section 1241 and the second downstream pipe section 1243. The second upstream pipe section 1241 is connected to the second upstream channel 116, and the second downstream pipe section 1243 is connected to the second downstream channel 117.

[0074] Optionally, both the second upstream pipe section 1241 and the second downstream pipe section 1243 extend along the radial direction of the main flow channel 111. It can be understood that the second upstream pipe section 1241 and the second downstream pipe section 1243 can be arranged in parallel, that is, the angles between the second upstream pipe section 1241 and the second measurement pipe section 1242 and between the second downstream pipe section 1243 and the second measurement pipe section 1242 are the same. For example, they are both 90°; or, the angles between the second upstream pipe section 1241 and the second measurement pipe section 1242 and between the second downstream pipe section 1243 and the second measurement pipe section 1242 can both be acute angles; or, the angles between the second upstream pipe section 1241 and the second measurement pipe section 1242 and between the second downstream pipe section 1243 and the second measurement pipe section 1242 can both be obtuse angles.

[0075] By adopting the above technical solution, the structure of the second pipeline 124 is simplified, which is beneficial to the flow of fluid in the second pipeline 124.

[0076] In some embodiments, the first pipeline 121 and the second pipeline 124 have the same structure.

[0077] It can be understood that the first pipeline 121 and the second pipeline 124 have the same shape and size.

[0078] In other embodiments, on the premise of ensuring that the first measuring pipe section 1212 and the second measuring pipe section 1242 have the same structure, the structures of the first pipeline 121 and the second pipeline 124 may be different.

[0079] In some embodiments, the mass flowmeter 10 further includes a laminar flow element 13 disposed in the main flow channel 111.

[0080] Wherein, the inlet of the first upstream channel 114 and the outlet of the first downstream channel 115 are respectively on both sides of the laminar flow element 13 in the axial direction of the main flow channel 111; the inlet of the second upstream channel 116 and the outlet of the second downstream channel 117 are also respectively on both sides of the laminar flow element 13 in the axial direction of the main flow channel 111.

[0081] The laminar flow element 13 is disposed in the main flow channel 111 for forming a stable laminar flow state to ensure accurate diversion of the flow rate through the flow sensor 12 and the flow rate of the main flow channel 111.

[0082] In other embodiments, in some small measurement ranges, the laminar flow element 13 may not be provided in the main flow channel 111.

[0083] In some embodiments, at least one of the first upstream thermistor 122, the first downstream thermistor 123, the second upstream thermistor 125, and the second downstream thermistor 126 is a winding structure.

[0084] It can be understood that one of the first upstream thermistor 122, the first downstream thermistor 123, the second upstream thermistor 125, and the second downstream thermistor 126 is a winding structure, and the rest can be a cylindrical structure; or, two of the first upstream thermistor 122, the first downstream thermistor 123, the second upstream thermistor 125, and the second downstream thermistor 126 are winding structures, and the rest can be a cylindrical structure; or, three of the first upstream thermistor 122, the first downstream thermistor 123, the second upstream thermistor 125, and the second downstream thermistor 126 are winding structures, and the rest can be a cylindrical structure; or, the first upstream thermistor 122, the first downstream thermistor 123, the second upstream thermistor 125, and the second downstream thermistor 126 are all winding structures.

[0085] In other embodiments, the first upstream thermistor 122, the first downstream thermistor 123, the second upstream thermistor 125, and the second downstream thermistor 126 are all cylindrical structures.

[0086] In some embodiments, the first pipeline 121 and the second pipeline 124 are capillary tubes.

[0087] By adopting the above technical solution, the flow sensor 12 is less affected by temperature and pressure during measurement.

[0088] In other embodiments, the first pipeline 121 is a capillary tube, and the second pipeline 124 is a tube with a similar function to a capillary tube; or, the second pipeline 124 is a capillary tube, and the first pipeline 121 is a tube with a similar function to a capillary tube.

[0089] As Figure 6 shown, a second aspect of the present application proposes a thermal mass flow controller 100, which includes a main valve 14 and the thermal mass flowmeter 10 as described in the first aspect. The main valve 14 is installed at the fluid outlet 113 of the thermal mass flowmeter 10.

[0090] It should be noted that the flow sensor 12 further includes a control circuit, and the opening size of the main valve 14 is controlled by the flow value measured by the flow sensor 12. The specific control process is as follows:

[0091] Sensor analog front-end circuit: It includes a preprocessing circuit that performs operations such as filtering, amplifying, operating, and multiplexing on analog signals, receives the analog signals uploaded by the flow sensor 12 and transmits them to the ADC for acquisition.

[0092] Analog-to-digital converter (ADC): It is responsible for converting the analog signals collected by the flow sensor 12 and the analog signals of the NTC thermistor into digital signals for the microcontroller unit (MCU) to process.

[0093] Microcontroller unit (MCU): The MCU is the calculation and control center of the system. It receives the digital signals from the ADC, calculates the actual flow based on the Vu and Vd values on the flow sensor 12 and the NTC temperature value detected in real time, and generates corresponding control signals to send to the DAC.

[0094] Digital-to-analog converter (DAC): The DAC converts the digital control signals generated by the MCU into analog signals to adjust the input control signals of the piezoelectric drive circuit to achieve precise control of the flow.

[0095] The thermal mass flow controller 100 adopts any one or more embodiments of the above thermal mass flowmeter 10, and thus has the beneficial effects of the above embodiments, which will not be elaborated here one by one.

[0096] The technical solution of this application has broad application prospects in achieving high-precision and high-stability flow control. The following are the known and potential technical and product application fields of this application, as well as their specific application methods:

[0097] Semiconductor manufacturing: Key steps such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) in the semiconductor manufacturing process require extremely high gas flow control accuracy. The installation attitude flow correction technology of this application can provide more accurate flow data to ensure the consistency of the manufacturing process and the quality of products.

[0098] Pharmaceutical industry: In the field of biopharmaceuticals, especially in the process of culturing cells and producing drugs, precise gas control is crucial. This application can improve the accuracy of flow control to ensure the precision and safety of drug synthesis.

[0099] Environmental monitoring equipment: In environmental protection fields such as air quality monitoring and water quality detection, continuous and precise monitoring and control of sampling flow are required. This application can provide fast response and high-precision flow monitoring to improve the reliability of environmental monitoring.

[0100] Laboratory and scientific research equipment: Scientific research experiments often require precise control and measurement of extremely small gas or liquid flows. The technical solution of this application can provide fine flow control for various laboratories to support the precision and efficiency of scientific research work.

[0101] Chemical process control: In the fields of chemical production and fine chemicals, the precise ratio and control of fluids directly affect product quality. The technical solution of this application provides key control parameters for the fine chemical process by providing stable and precise flow measurement.

[0102] Aerospace and military applications: In aerospace and military equipment, the accuracy and response time of flow control are crucial for the performance of the entire system. This application can provide the required high-precision flow control in these high-demand applications.

[0103] Food and beverage industry: In the production process of food and beverages, ensuring precise gas and liquid addition amounts is necessary to guarantee product taste and quality standards. This application can provide high-precision and high-stability flow control in these applications.

[0104] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. A mass flow meter, characterized in that: The invention comprises a main pipeline and a flow sensor, wherein the main pipeline has a main flow channel, and the flow sensor is installed on the main pipeline; the flow sensor comprises a first pipeline, a first upstream thermistor, a first downstream thermistor, a second pipeline, a second upstream thermistor and a second downstream thermistor, wherein two ends of the first pipeline are respectively connected to the upstream and downstream of the main flow channel, the first pipeline comprises a first measuring pipe section, and the first upstream thermistor and the first downstream thermistor are arranged on the first measuring pipe section; two ends of the second pipeline are respectively connected to the upstream and downstream of the main flow channel, the second pipeline comprises a second measuring pipe section, and the second upstream thermistor and the second downstream thermistor are arranged on the second measuring pipe section; wherein the first measuring pipe section and the second measuring pipe section are arranged in parallel and have the same cross-sectional area, and the arrangement direction of the first upstream thermistor and the first downstream thermistor is opposite to the arrangement direction of the second upstream thermistor and the second downstream thermistor.

2. The mass flow meter according to claim 1, characterized in that: The first measuring tube section and the second measuring tube section are both perpendicular to the axial direction of the main flow channel; or, the first measuring tube section and the second measuring tube section are both parallel to the axial direction of the main flow channel.

3. The mass flow meter according to claim 1, characterized in that: The main pipeline is provided with a first upstream channel, a first downstream channel, a second upstream channel and a second downstream channel. The first pipeline connects the upstream and downstream of the main channel through the first upstream channel and the first downstream channel, and the second pipeline connects the upstream and downstream of the main channel through the second upstream channel and the second downstream channel; the inlet of the first upstream channel and the inlet of the second upstream channel are arranged close to each other, and the outlet of the first downstream channel and the outlet of the second downstream channel are arranged close to each other.

4. The mass flow meter according to claim 3, characterized in that: The first pipeline further includes a first upstream pipe section and a first downstream pipe section, the first measuring pipe section is connected between the first upstream pipe section and the first downstream pipe section, the first upstream pipe section is connected to the first upstream channel, and the first downstream pipe section is connected to the first downstream channel.

5. The mass flow meter according to claim 3, characterized in that: The second pipeline also includes a second upstream pipe section and a second downstream pipe section, the second measuring pipe section is connected between the second upstream pipe section and the second downstream pipe section, the second upstream pipe section is connected to the second upstream channel, and the second downstream pipe section is connected to the second downstream channel.

6. The mass flow meter according to any one of claims 1 to 5, characterized in that: The first pipeline and the second pipeline have the same structure.

7. The mass flow meter according to any one of claims 1 to 5, characterized in that: The mass flow meter further includes a laminar flow element disposed in the main flow channel.

8. The mass flow meter according to any one of claims 1 to 5, characterized in that: At least one of the first upstream thermistor, the first downstream thermistor, the second upstream thermistor, and the second downstream thermistor is a winding structure.

9. The mass flow meter according to any one of claims 1 to 5, characterized in that: The first pipeline and / or the second pipeline is a capillary tube.

10. A mass flow controller, characterized in that: It comprises a main valve and a mass flow meter as claimed in any one of claims 1 to 9, wherein the main valve is installed at a fluid outlet of the mass flow meter.

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