Gas mass flow controller

Abstract

The invention discloses a gas mass flow controller, which relates to the technical field of gas mass flow measurement and control, and comprises a gas circuit seat, a sensor, an integrated circuit board and an electromagnetic valve which are sequentially connected end to end, and a gas main circuit, a first gas branch and a second gas branch which are communicated with one another are arranged in the gas circuit seat. The first gas branch and the second gas branch are respectively communicated with the sensor, the flow dividing frame and the plurality of flow limiting sheets are arranged in the gas main path, and the plurality of flow limiting sheets are stacked on the flow dividing frame; when gas enters the gas path seat, one part of the gas penetrates through the flow dividing frame, flows through the plurality of flow limiting pieces and then enters the gas main path, the other part of the gas flows through the sensor from the first gas branch and enters the gas main path through the second gas branch, the two parts of the gas are mixed, and meanwhile the sensor transmits a signal to the integrated circuit board and controls the electromagnetic valve to be opened. And the mixed gas flows out of the gas path seat from the gas main path. The gas flow can be accurately controlled, the stability is high, the precision is high, and the application range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of gas mass flow measurement and control, and in particular to a gas mass flow controller. Background Art

[0002] The gas mass flow controller is used to measure and control the flow of gas, including a flow measuring sensor, a gas path seat (including a diverter and a connector), a solenoid valve, and a control circuit PCB. Due to the structural problem of the diverter, the gas flow stability is poor, the existing gas path seat has poor gas stability, and the air tightness is not good. At the same time, if the sensor capillary and the thermal resistance wire do not match, it will also lead to poor accuracy.

[0003] That is, the existing gas mass flow controller has the following defects: 1. Unable to accurately control gas flow and poor stability; 2. Poor accuracy.

[0004] This article aims to address at least one of the above problems. Summary of the invention

[0005] In view of the above-mentioned shortcomings currently existing, the present invention provides a gas mass flow controller which can accurately control the gas flow rate, has high stability, high precision, wide application range and strong applicability.

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: A gas mass flow controller comprises a gas circuit seat, a sensor, an integrated circuit board, and a solenoid valve connected end to end in sequence, wherein a gas main circuit, a first gas branch circuit, and a second gas branch circuit connected to each other are arranged in the gas circuit seat, wherein the first gas branch circuit and the second gas branch circuit are connected to the sensor respectively, and the gas mass flow controller further comprises a shunt frame and a plurality of current limiting plates, both of which are arranged in the gas main circuit, and the plurality of current limiting plates are stacked and installed on the shunt frame; when the gas enters the gas circuit seat, a part of the gas passes through the shunt frame and flows through the plurality of current limiting plates before entering the gas main circuit, and another part of the gas flows from the first gas branch circuit through the sensor and passes through the second gas branch circuit before entering the gas main circuit, and when the two parts of the gas are mixed, the sensor transmits a signal to the integrated circuit board and controls the solenoid valve to open, so that the mixed gas flows out of the gas circuit seat from the gas main circuit.

[0007] According to one aspect of the present invention, the flow limiting plate includes an integrally arranged flow limiting body and a plurality of flow limiting channels, and the plurality of flow limiting channels are regularly distributed around the flow limiting body.

[0008] According to one aspect of the present invention, the flow limiting body is in a plate shape, the flow limiting channel is in a groove shape, and a plurality of flow limiting channels are arranged in a circular array on the flow limiting body.

[0009] According to one aspect of the present invention, the flow splitter frame includes a frame body and a connecting portion, which are fixed. The frame body is provided with a hole for gas to pass through, and a plurality of flow limiting plates are stacked and sleeved on the connecting portion.

[0010] According to one aspect of the present invention, the connecting portion is composed of a plurality of connecting rods, which are evenly spaced circumferentially and fixed on the frame body.

[0011] According to one aspect of the present invention, the connecting portion is a columnar structure, and a plurality of current limiting plates are stacked and concentrically sleeved on the columnar structure.

[0012] According to one aspect of the present invention, the current limiting body is provided with a hole, and the current limiting sheet is sleeved on the connecting portion through the hole.

[0013] According to one aspect of the present invention, a capillary tube and a plurality of groups of thermal resistance wires are provided in the sensor, the plurality of groups of thermal resistance wires are wound around the capillary tube, and the capillary tube is respectively connected to the first gas branch and the second gas branch.

[0014] According to one aspect of the present invention, the capillary has an outer diameter of 0.35 mm to 0.37 mm, an inner diameter of 0.25 mm to 0.26 mm, a length of 65 mm to 65.1 mm, an inner surface roughness of 0.4, an outer surface roughness not exceeding 0.4, and a hardness of HV200±50.

[0015] According to one aspect of the present invention, the diameter of the thermal resistance wire is 0.006 inches, the resistance value is 340 ohms, and the allowable deviation of the resistance value is ±3%.

[0016] Advantages of the present invention: When the gas flows through the splitter and several limiting plates, the gas flow will be limited and rectified to become a stable fluid state; at the same time, a part of the gas flows through the sensor, and the two groups of thermal resistance wires in the sensor are wrapped around the capillary. When the gas flows through, the resistance of the two groups of thermal resistance wires will change, and at the same time, it will be fed back to the PCBA, and after calculation by the software algorithm, an instruction will be given to the solenoid valve, and then the solenoid valve will open to a certain extent, so that the gas reaches the set flow value; in this way, the present invention can accurately control the gas flow, and the unique design of the splitter and several limiting plates can ensure the stability of the internal flow path, with a wide range of applications and strong applicability. The unique specification combination of the thermal resistance wire and the capillary ensures high precision and high stability of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a schematic diagram of the local structure of the present invention; Figure 3 It is a schematic diagram of the partial explosion structure of the present invention; Figure 4 It is a structural schematic diagram of the flow dividing frame of the present invention; Figure 5 It is a schematic diagram of the structure of the current limiting plate of the present invention.

[0019] The names corresponding to the serial numbers in the figure are as follows: 1. Gas path seat; 2. Diverter frame; 21. Frame body; 22. Connecting part; 3. Current limiting plate; 31. Current limiting body; 32. Current limiting channel; 4. Sensor; 5. Integrated circuit board; 6. Solenoid valve; 7. First gas branch; 8. Second gas branch; 9. Gas main line; 10. Capillary; 11. Thermal resistance wire. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical aspects in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "top", "bottom", "one side", "the other side", "front", "back", "middle part", "inside", "top", "bottom", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] Embodiment 1

[0022] like Figure 1 - Figure 5As shown, a gas mass flow controller includes a gas circuit seat 1, a flow divider 2, a plurality of flow limiting plates 3, a sensor 4, an integrated circuit board 5 (PCBA), and a solenoid valve 6, wherein a capillary 10 and a plurality of thermal resistance wires 11 are provided in the sensor 4, and the sensor 4 and the solenoid valve 6 are respectively installed at both ends of the gas circuit seat 1, and the PCBA is electrically connected to the sensor 4 and the solenoid valve 6. The gas circuit seat 1 is provided with a gas main circuit 9, a first gas branch 7, and a second gas branch 8 that are connected to each other, wherein the first gas branch 7 and the second gas branch 8 are respectively connected to both ends of the capillary 10 of the sensor 4. The flow divider 2 and the plurality of flow limiting plates 3 are all arranged in the gas main circuit 9 for limiting and rectifying the gas; wherein the flow divider 2 includes a frame body 21 and a connecting portion 22, which are integrally formed or welded to each other, and a hole for gas to pass through is provided on the frame body 21; the plurality of flow limiting plates 3 are closely fitted and stacked, and are concentrically sleeved on the connecting portion 22 of the flow divider 2. The sensor 4 is provided with a capillary 10 and two groups of thermal resistance wires 11 arranged at intervals and wound around the capillary 10; the specifications of the capillary 10 are: Φ0.35 (+0.02) x Φ0.25 (+0.01) x65 (+0.1), inner surface roughness: Ra0.4, outer surface roughness ≤Ra0.4, hardness: HV200±50, that is, the outer diameter of the capillary 10 is 0.35mm~0.37mm, the inner diameter is 0.25mm~0.26mm, and the length is 65mm~65.1mm; the specifications of the thermal resistance wire 11 are: diameter 0.006 inches, and the resistance value is 340 (+ / -3%) ohms.

[0023] When the gas enters the gas path seat 1, it will be split, and part of the gas will pass through the splitter frame 2 and flow through several flow limiting plates 3 before entering the gas main path 9. At this time, the flow of the gas will be limited and rectified to become a stable fluid state; at the same time, the other part of the gas enters one end of the capillary 10 from the first gas branch 7, flows through the sensor 4, and then enters the second gas branch 8 from the other end of the capillary 10, and flows out from the second gas branch 8 and enters the gas main path 9 (when the gas flows through the capillary 10, the resistance of the two groups of thermal resistance wires 11 will change, and this change signal will be transmitted to the PCBA by the sensor 4); the two parts of the gas meet and mix together in the gas main path 9, and when the PCBA receives the resistance change signal fed back by the sensor 4, the PCBA will give an instruction to the solenoid valve 6 after calculation through the software algorithm, and control the solenoid valve 6 to open to a certain extent, so that the mixed gas flows out of the gas path seat 1 from the gas main path 9, that is, the gas finally flowing out reaches the set flow value.

[0024] In this embodiment, the connecting portion 22 of the flow dividing frame 2 is composed of three connecting rods, which are arranged equidistantly in the circumferential direction and fixed in the middle position of the end face of the frame body 21; the connecting rods are round rod-shaped, and the arrangement of multiple connecting rods makes the structure have a certain elasticity, which is convenient for the assembly of the current limiting plate 3.

[0025] In this embodiment, the flow limiting plate 3 includes an integrally arranged flow limiting body 31 and a plurality of flow limiting channels 32, wherein the flow limiting body 31 is in the shape of a circular plate, and a hole is provided in the center of the flow limiting body 31, so that the flow limiting plate 3 can be concentrically sleeved on the connecting portion 22 through the hole; the flow limiting channel 32 is in the shape of a U-shaped groove, and a plurality of flow limiting channels 32 are arranged in a circular array on the flow limiting body 31, and the flow limiting channel 32 is located on an end face of the flow limiting body 31 facing the gas inflow direction. Through the unique design of the flow limiting plate 3 and the diverter frame 2, after the calculation of fluid mechanics, each flow limiting plate 3 passes a fixed flow rate, and through the number of flow limiting plates 3, a fixed flow range is achieved; the present invention only needs to adjust the number of stacked flow limiting plates 3, that is, it can adjust or adapt to different gas flow rates, and has a wide range of application and strong applicability; at the same time, the unique flow path design of the flow limiting plate 3 itself ensures the stability of the flow rate.

[0026] In this embodiment, each current limiting plate 3 has many flow channel designs, that is, each current limiting plate 3 has a number of flow limiting channels 32, which are evenly distributed to form multiple channels, and the flow rate passing through each current limiting plate 3 is also the same, forming a laminar flow element for rectification; each current limiting plate 3 is a separate piece, and then they are not separated, but are fitted together piece by piece, and each current limiting plate 3 has the same structure and is stacked together.

[0027] The beneficial effects of this embodiment are: the present invention can accurately control the gas flow rate, the unique design of the flow divider 2 and the plurality of flow limiting plates 3 can ensure the stability of the internal flow path, and has a wide range of applications and strong applicability. The unique specification combination of the thermal resistance wire 11 and the capillary 10 ensures high precision and high stability of the measurement.

[0028] Embodiment 2

[0029] A gas mass flow controller includes a gas circuit seat 1, a flow divider 2, a plurality of flow limiting plates 3, a sensor 4, an integrated circuit board 5 (PCBA), and a solenoid valve 6, wherein a capillary 10 and a plurality of thermal resistance wires 11 are arranged in the sensor 4, and the sensor 4 and the solenoid valve 6 are respectively mounted at both ends of the gas circuit seat 1, and the PCBA is electrically connected to the sensor 4 and the solenoid valve 6. The gas circuit seat 1 is provided with a gas main circuit 9, a first gas branch 7, and a second gas branch 8 that are connected to each other, wherein the first gas branch 7 and the second gas branch 8 are respectively connected to both ends of the capillary 10 of the sensor 4. The flow divider 2 and the plurality of flow limiting plates 3 are arranged in the gas main circuit 9 for limiting and rectifying the gas; wherein the flow divider 2 includes a frame body 21 and a connecting portion 22, which are integrally formed or welded to each other, and a hole for gas to pass through is arranged on the frame body 21; the plurality of flow limiting plates 3 are closely fitted and stacked, and are concentrically sleeved on the connecting portion 22 of the flow divider 2. The sensor 4 is provided with a capillary 10 and two groups of thermal resistance wires 11 arranged at intervals and wound around the capillary 10; the specifications of the capillary 10 are: Φ0.35 (+0.02) x Φ0.25 (+0.01) x65 (+ 0.1), inner surface roughness: Ra0.4, outer surface roughness ≤Ra0.4, hardness: HV200±50, that is, the outer diameter of the capillary 10 is 0.35mm~0.37mm, the inner diameter is 0.25mm~0.26mm, and the length is 65mm~65.1mm; the specifications of the thermal resistance wire 11 are: diameter 0.006 inches, and the resistance value is 340 (+ / -3%) ohms.

[0030] When the gas enters the gas path seat 1, it will be split, and part of the gas will pass through the splitter frame 2 and flow through several flow limiting plates 3 before entering the gas main path 9. At this time, the flow of the gas will be limited and rectified to become a stable fluid state; at the same time, the other part of the gas enters one end of the capillary 10 from the first gas branch 7, flows through the sensor 4, and then enters the second gas branch 8 from the other end of the capillary 10, and flows out from the second gas branch 8 and enters the gas main path 9 (when the gas flows through the capillary 10, the resistance of the two groups of thermal resistance wires 11 will change, and this change signal will be transmitted to the PCBA by the sensor 4); the two parts of the gas meet and mix together in the gas main path 9, and when the PCBA receives the resistance change signal fed back by the sensor 4, the PCBA will give an instruction to the solenoid valve 6 after calculation through the software algorithm, and control the solenoid valve 6 to open to a certain extent, so that the mixed gas flows out of the gas path seat 1 from the gas main path 9, that is, the gas finally flowing out reaches the set flow value.

[0031] In this embodiment, the connecting portion 22 of the flow splitter frame 2 is a columnar structure, and a plurality of current limiting plates 3 are stacked and concentrically sleeved on the columnar structure; the connecting portion 22 is cylindrical and integrally formed at the end of the frame body 21, so it is easy to manufacture and process.

[0032] In this embodiment, the flow limiting plate 3 includes an integrally arranged flow limiting body 31 and a plurality of flow limiting channels 32, wherein the flow limiting body 31 is in the shape of a circular plate, and a hole is provided in the center of the flow limiting body 31, so that the flow limiting plate 3 can be concentrically sleeved on the connecting portion 22 through the hole; the flow limiting channel 32 is in the shape of a U-shaped groove, and a plurality of flow limiting channels 32 are arranged in a circular array on the flow limiting body 31, and the flow limiting channel 32 is located on an end face of the flow limiting body 31 facing the gas inflow direction. Through the unique design of the flow limiting plate 3 and the diverter frame 2, after the calculation of fluid mechanics, each flow limiting plate 3 passes a fixed flow rate, and through the number of flow limiting plates 3, a fixed flow range is achieved; the present invention only needs to adjust the number of stacked flow limiting plates 3, that is, it can adjust or adapt to different gas flow rates, and has a wide range of application and strong applicability; at the same time, the unique flow path design of the flow limiting plate 3 itself ensures the stability of the flow rate.

[0033] In this embodiment, each current limiting plate 3 has many flow channel designs, that is, each current limiting plate 3 has a number of flow limiting channels 32, which are evenly distributed to form multiple channels, and the flow rate passing through each current limiting plate 3 is also the same, forming a laminar flow element for rectification; each current limiting plate 3 is a separate piece, and then they are not separated, but are fitted together piece by piece, and each current limiting plate 3 has the same structure and is stacked together.

[0034] The beneficial effects of this embodiment are: the present invention can accurately control the gas flow rate, the unique design of the flow divider 2 and the plurality of flow limiting plates 3 can ensure the stability of the internal flow path, and has a wide range of applications and strong applicability. The unique specification combination of the thermal resistance wire 11 and the capillary 10 ensures high precision and high stability of the measurement.

[0035] Embodiment 3

[0036] The present embodiment provides a flow limiter, which is used in a gas mass flow controller, and is used for gas flow limiting and rectification, i.e., gas mass flow control and other occasions; the flow limiter comprises a flow splitter frame 2, and a plurality of flow limiting plates 3, wherein the plurality of flow limiting plates 3 are stacked and installed on the flow splitter frame 2.

[0037] In this embodiment, the splitter frame 2 includes a frame body 21 and a connecting portion 22, which are integrally formed or welded to each other. The frame body 21 is provided with a channel for gas to pass through; a plurality of flow limiting plates 3 are tightly stacked and concentrically sleeved on the connecting portion 22 of the splitter frame 2.

[0038] In this embodiment, the connection part 22 of the flow splitter frame 2 is composed of three connecting rods, which are arranged equidistantly in the circumferential direction and fixed in the middle position of the end face of the frame body 21; the connecting rods are round rod-shaped, and the arrangement of multiple connecting rods makes the structure have a certain elasticity, which is convenient for the assembly of the current limiting plate 3. Alternatively, the connection part 22 of the flow splitter frame 2 is a columnar structure, and a plurality of current limiting plates 3 are stacked and concentrically sleeved on the columnar structure; the connection part 22 is cylindrical and integrally formed at the end of the frame body 21, so it is easy to manufacture and process.

[0039] In this embodiment, the flow limiting plate 3 includes an integrally arranged flow limiting body 31 and a plurality of flow limiting channels 32, wherein the flow limiting body 31 is in the shape of a plate, which may be a circular plate, and a hole is provided in the center of the flow limiting body 31, so that the flow limiting plate 3 can be concentrically sleeved on the connecting portion 22 through the hole; the flow limiting channel 32 is in the shape of a groove, which may be a U-shaped groove, and a plurality of flow limiting channels 32 are arranged in a circular array on the flow limiting body 31, and the flow limiting channel 32 is located on an end face of the flow limiting body 31 facing the gas inflow direction.

[0040] In this embodiment, each current limiting plate 3 has many flow channel designs, that is, each current limiting plate 3 has a number of flow limiting channels 32, which are evenly distributed to form multiple channels, and the flow rate passing through each current limiting plate 3 is also the same, forming a laminar flow element for rectification; each current limiting plate 3 is a separate piece, and then they are not separated, but are fitted together piece by piece, and each current limiting plate 3 has the same structure and is stacked together.

[0041] The beneficial effects of this embodiment are: the present invention creates a unique flow limiter design, which is composed of a flow limiting plate 3 and a diverter frame 2. After fluid mechanics calculations, each flow limiting plate 3 passes a fixed flow rate, and the number of flow limiting plates 3 is adjusted to achieve a fixed flow range; the present invention only needs to adjust the number of stacked flow limiting plates 3, that is, it can adjust or adapt to different gas flow rates, and has a wide range of applications and strong applicability; at the same time, the unique flow path design of the flow limiting plate 3 itself ensures the stability of the flow rate.

[0042] Embodiment 4

[0043] This embodiment provides a sensor 4 for use in a gas mass flow controller; the sensor 4 includes a capillary 10 and a plurality of thermal resistance wires 11 arranged inside the sensor 4 , wherein the plurality of thermal resistance wires 11 are wound around the capillary 10 .

[0044] In this embodiment, a capillary 10 and two groups of thermal resistance wires 11 are arranged at intervals and wound around the capillary 10 in the sensor 4. The specifications of the capillary 10 are: Φ0.35 (+0.02) x Φ0.25 (+0.01) x65 (+ 0.1), inner surface roughness: Ra0.4, outer surface roughness ≤ Ra0.4, hardness: HV200 ± 50; that is, the outer diameter of the capillary 10 is 0.35mm ~ 0.37mm, the inner diameter is 0.25mm ~ 0.26mm, and the length is 65mm ~ 65.1mm. The specifications of the thermal resistance wire 11 are: diameter 0.006 inches, and the resistance value is 340 (+ / -3%) ohms. When the gas flows through the capillary 10, the resistance of the two groups of thermal resistance wires 11 will change, and this change signal will be transmitted to the PCBA by the sensor 4.

[0045] The beneficial effect of this embodiment is that: the present invention designs a unique sensor structure, a capillary 10 with two sections of thermal resistance wires 11 wound on it; the unique specification combination of the thermal resistance wire 11 and the capillary 10 ensures the accuracy and stability of the measurement.

[0046] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes, combinations or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A gas mass flow controller, comprising a gas circuit seat (1), a sensor (4), an integrated circuit board (5), and a solenoid valve (6) connected end to end in sequence, wherein the gas circuit seat (1) is provided with a gas main circuit (9), a first gas branch circuit (7), and a second gas branch circuit (8) which are connected to each other, wherein the first gas branch circuit (7) and the second gas branch circuit (8) are respectively connected to the sensor (4), and characterized in that: The gas mass flow controller further comprises a flow divider (2) and a plurality of flow limiting plates (3), both of which are arranged in a gas main path (9), and the plurality of flow limiting plates (3) are stacked and installed on the flow divider (2); when the gas enters the gas path seat (1), a part of the gas passes through the flow divider (2) and flows through the plurality of flow limiting plates (3) before entering the gas main path (9), and another part of the gas flows from the first gas branch path (7) through the sensor (4) and passes through the second gas branch path (8) before entering the gas main path (9); when the two parts of gas are mixed, the sensor (4) transmits a signal to the integrated circuit board (5) and controls the electromagnetic valve (6) to open, so that the mixed gas flows out of the gas path seat (1) from the gas main path (9).

2. The gas mass flow controller according to claim 1, characterized in that: The flow limiting plate (3) comprises a flow limiting body (31) and a plurality of flow limiting channels (32) which are arranged integrally, and the plurality of flow limiting channels (32) are regularly distributed around the flow limiting body (31).

3. The gas mass flow controller according to claim 2, characterized in that: The flow limiting body (31) is in the shape of a plate, the flow limiting channel (32) is in the shape of a groove, and a plurality of flow limiting channels (32) are arranged in a circular array on the flow limiting body (31).

4. The gas mass flow controller according to claim 2, characterized in that: The flow splitter frame (2) comprises a frame body (21) and a connecting portion (22), which are fixed. The frame body (21) is provided with a hole for gas to pass through, and a plurality of flow limiting plates (3) are stacked and sleeved on the connecting portion (22).

5. The gas mass flow controller according to claim 4, characterized in that: The connecting portion (22) is composed of a plurality of connecting rods, which are evenly spaced in the circumferential direction and fixed on the frame body (21).

6. The gas mass flow controller according to claim 4, characterized in that: The connecting portion (22) is a columnar structure, and a plurality of current limiting sheets (3) are stacked and concentrically sleeved on the columnar structure.

7. The gas mass flow controller according to claim 4, characterized in that: The current limiting body (31) is provided with a hole, and the current limiting sheet (3) is sleeved on the connecting portion (22) through the hole.

8. The gas mass flow controller according to claim 1, characterized in that: The sensor (4) is provided with a capillary tube (10) and multiple groups of thermal resistance wires (11), the multiple groups of thermal resistance wires (11) are wound around the capillary tube (10), and the capillary tube (10) is respectively connected to the first gas branch (7) and the second gas branch (8).

9. The gas mass flow controller according to claim 8, characterized in that: The capillary (10) has an outer diameter of 0.35 mm to 0.37 mm, an inner diameter of 0.25 mm to 0.26 mm, a length of 65 mm to 65.1 mm, an inner surface roughness of 0.4, an outer surface roughness not exceeding 0.4, and a hardness of HV200±50.

10. The gas mass flow controller according to claim 8, characterized in that: The diameter of the thermal resistance wire (11) is 0.006 inches, the resistance value is 340 ohms, and the allowable deviation of the resistance value is ±3%.

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