Flow channel structure of thermal gas micro-flow sensor

Abstract

The invention relates to the technical field of gas micro-flow sensors, in particular to a thermal gas micro-flow sensor, a flow channel structure and a design method. A rib plate layer, a groove layer and a chip layer of the runner structure of the thermal gas micro-flow sensor are fixedly connected through detachable fasteners, a rib plate is inserted into a groove, first ventilation intervals are formed between the rib plate and the two ends of the groove in the length direction, second ventilation intervals are formed between the rib plate and the bottom of the groove, and a mounting groove is opposite to a through groove in position. And the gas inlet, the gas outlet, the second ventilation interval and the two first ventilation intervals are communicated. By replacing the rib plate layers with different rib plate sizes and / or the groove layers with different sizes, the shape and size of the cross section of the runner can be adjusted. Through mechanical structure innovation, the flow channel performance is convenient and adjustable, great flexibility is provided for sensor research and development, the research and development period is shortened, and the iteration cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of gas microflow sensor technology, and in particular to a thermal gas microflow sensor, its flow channel structure, and the design method of the flow channel structure. Background Technology

[0002] Thermal MEMS gas flow sensors are widely used due to their advantages such as small size, fast response, and high sensitivity. The core detection element of the sensor, the "MEMS chip," is placed in the flow channel. The geometry of the flow channel (such as shape, size, and length) directly affects the gas flow state (such as velocity distribution, laminar / turbulent flow) passing through the chip, and thus plays a decisive role in the sensor's key performance parameters such as sensitivity, response time, measurement range, linearity, and stability.

[0003] Currently, most common sensor flow channels are integrally machined. For example, Chinese patent application CN109579928A, entitled "A Flow Channel and Sealing Structure for a Thermal Micro-Flow Measurement Sensor," employs a welded structure, which improves sealing performance and pressure resistance reliability. However, once this type of flow channel is manufactured, its shape and size are fixed, making it impossible to flexibly adjust the cross-sectional shape or size. This hinders iterative debugging and rapid replacement or adjustment of flow channel parameters. When different measuring gases, different flow ranges, or optimization of sensor performance are required, the entire flow channel component must be redesigned and manufactured. This process is not only time-consuming but also costly, severely restricting the R&D efficiency and iteration speed of sensor products.

[0004] Therefore, there is an urgent need in this field for a solution that can quickly and cost-effectively adjust the size and shape of the flow channel to accelerate the research and development and performance optimization of sensors. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and solve the technical problem that the flow channel structure of thermal gas micro-flow sensors is not adjustable, resulting in long research and development cycles and high iteration costs.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a flow channel structure for a thermal gas micro-flow sensor, comprising: The rib layer includes a substrate, a gas inlet and a gas outlet penetrating the substrate, and a rib mounted on and protruding from the substrate, the rib being located between the gas inlet and the gas outlet. The grooved layer has grooves for accommodating ribs, and the bottom of the grooves has channels for ventilation. The chip layer includes a base plate, which has mounting slots for mounting printed circuit boards and chips, and the bottom of the mounting slots has vias for metal pins to pass through. The ribbed plate layer, the groove layer and the chip layer are fixedly connected by detachable fasteners. The ribbed plate is inserted into the groove and has a first ventilation gap at both ends in the length direction of the groove, and a second ventilation gap between the ribbed plate and the bottom of the groove. The positions of the installation groove and the through groove are opposite, and the gas inlet, the gas outlet, the second ventilation gap and the two first ventilation gaps are connected; The thickness d of the ribbed plate and the width D of the groove satisfy the relationship: d ≤ D; When d = D, the cross-section of the flow channel formed after assembly is rectangular; when d < D, the cross-section of the flow channel formed after assembly is U-shaped; By replacing the ribbed plate layer with different ribbed plate sizes and / or the groove layer with different sizes, the shape and size of the cross-section of the flow channel can be adjusted.

[0007] Optionally, at least one sealing ring is provided on the contact plane between the ribbed plate layer and the groove layer and between the groove layer and the chip layer.

[0008] Optionally, arc transition structures are provided on the end walls at both ends in the length direction of the groove; On one end of the ribbed plate facing away from the substrate, rounded corners are provided on both sides in the length direction.

[0009] Optionally, raised blocks are provided on the contact surface between the chip layer and the groove layer, and the installation groove is provided on the raised blocks; On the contact surface between the groove layer and the chip layer, there are receiving grooves for receiving the raised blocks.

[0010] In a second aspect, the present invention also provides a method for designing a flow channel structure of a thermal gas micro-flow sensor, which is used for designing the flow channel structure in any implementation manner of the first aspect, and includes the following steps: S1. Determine the measurement requirement parameters, including the type of the gas to be measured, the upstream and downstream pressures, the flow measurement range, the gas density and the kinematic viscosity of the gas ; S2.初选流道参数,初步选定流道横截面形状为矩形或U形,并选定一组初始流道特征尺寸:包括凹槽宽度D0、凹槽深度H0、肋板厚度d0、肋板高度h0; S3. Calculate the flow velocity and the Reynolds number: According to the maximum mass flow rate and the initially selected cross-sectional area S of the flow channel, calculate the maximum gas flow velocity:

[0011] Calculate the hydraulic diameter of the flow channel and calculate the Reynolds number: It should be noted that there is an error in the Chinese description of step S2 in the original text. The correct English translation should be: S2.初选流道参数,初步选定流道横截面形状为矩形或U形,并选定一组初始流道特征尺寸:包括凹槽宽度D0、凹槽深度H0、肋板厚度d0、肋板高度h0; S2.初选流道参数,初步选定流道横截面形状为矩形或U形,并选定一组初始流道特征尺寸:包括凹槽宽度D0、凹槽深度H0、肋板厚度d0、肋板高度h0;Determine if Re is less than 2000. If yes, proceed to step S4; otherwise, return to step S2 to reselect the flow channel parameters. S4. Fluid simulation verification: Based on the flow channel parameters selected in step S2, establish a fluid dynamics model for simulation to verify whether the gas flow in the flow channel is in a laminar state and evaluate the flow stability. If it meets the requirements, proceed to step S5; otherwise, return to step S2 to reselect the flow channel parameters. S5. Machining and Assembly: Based on the simulated flow channel parameters, machine the rib layer and groove layer parts, and assemble them with the chip layer to form the flow channel structure. S6. Performance Testing and Iteration: Perform performance testing on the assembled sensors. If the performance does not meet the requirements, replace the rib layer or groove layer parts with different feature dimensions and retest until the optimal flow channel parameter combination D1, H1, d1, h1 that meets the performance requirements is obtained.

[0012] Optionally, in step S5, multiple sets of serialized rib plate layers and groove layer parts are processed simultaneously, wherein the series values ​​of rib plate thickness d are selected in the range of 0.8d0 to 1.2d0, the series values ​​of rib plate height h are selected in the range of 0.8h0 to 1.2h0, the series values ​​of groove width D are selected in the range of 0.8D0 to 1.2D0, and the series values ​​of groove depth H are selected in the range of 0.8H0 to 1.2H0.

[0013] Optionally, in step S3, the cross-sectional area S of the flow channel is calculated as follows: When the cross-section of the flow channel is rectangular, S = s × w, where s is the flow channel height, w is the flow channel width, and s = H - h, w = d = D; When the cross-section of the flow channel is U-shaped, S = (D - d) × (H - h).

[0014] Optionally, in step S3, the hydraulic diameter The calculation method is as follows: When the cross-section of the flow channel is rectangular: When the cross-section of the flow channel is U-shaped: in The wetted perimeter of the flow channel cross-section. .

[0015] Optionally, in step S4, a heat source is set on the flow channel wall in the middle of the flow channel corresponding to the chip heating area in the fluid dynamics simulation model to simulate the working state of the chip. The length L of the flow channel satisfies: .

[0016] Thirdly, the present invention also provides a thermal gas microflow sensor, including the flow channel structure of any one of the first aspects; Printed circuit boards are installed in mounting slots; The chip is mounted on a printed circuit board or chip layer and is electrically connected to the printed circuit board by gold or aluminum wire bonding. The metal pin has one end connected to the printed circuit board and the other end passing through a via. Its root is sealed with potting compound.

[0017] The above-described technical solution of the present invention has the following advantages: The flow channel structure of the thermal gas microflow sensor provided by this invention features a rib layer, a groove layer, and a chip layer fixedly connected by detachable fasteners. The ribs are inserted into the grooves, with a first ventilation gap between the ribs and both ends of the groove along its length, and a second ventilation gap between the ribs and the bottom of the groove. The mounting groove and the through groove are positioned opposite each other, and the gas inlet, gas outlet, second ventilation gap, and two first ventilation gaps are connected. By replacing the rib layers with different rib sizes and / or the groove layers with different sizes, the cross-sectional shape and size of the flow channel can be adjusted. This invention, through mechanical structural innovation, achieves convenient and adjustable flow channel performance, providing great flexibility for sensor development, shortening the development cycle, and reducing iteration costs.

[0018] The flow channel structure design method for the thermal gas microflow sensor provided by this invention achieves convenient and adjustable flow channel performance. Starting from an initial guess of parameters, the optimal flow channel geometry parameters are quickly located through fluid simulation and component replacement testing. The entire process is time-efficient and low-cost, fully demonstrating the significant advantages of this invention in accelerating sensor research and development iteration.

[0019] The thermal gas microflow sensor provided by the present invention includes the above-mentioned flow channel structure. The overall structure and assembly are simple. The rib layer and the groove layer are adjusted only in the size of the rib and the groove. The parts are highly interchangeable and the cross-sectional shape and size of the flow channel can be easily adjusted. Attached Figure Description

[0020] The accompanying drawings are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not be consistent with the actual product.

[0021] Figure 1 This is a schematic diagram of the flow channel structure of a thermal gas microflow sensor according to Embodiment 1 of the present invention; Figure 2 yes Figure 1 Top view of the central channel structure; Figure 3 yes Figure 2 AA cross-sectional schematic diagram of the central channel structure; Figure 4 is Figure 2 Schematic diagram of the B-B section of the middle flow channel structure (rectangular cross-section d = D); Figure 5 is Figure 1 Schematic diagram of the middle flow channel structure in a disassembled state; Figure 6 is Figure 5 Schematic diagram of another angle of the middle flow channel structure in a disassembled state; Figure 7 is a schematic diagram of the U-shaped cross-section (d < D) of the flow channel structure of a thermal gas micro-flow sensor in Embodiment 1 of the present invention; Figure 8 is a schematic diagram of the cross-section of another flow channel structure in Embodiment 1 of the present invention (the cutting direction and position are the same as Figure 3 ); Figure 9 is a schematic diagram of the disassembled state of a thermal gas micro-flow sensor in an embodiment of the present invention; Figure 10 is a schematic diagram of the cross-section of a thermal gas micro-flow sensor in an embodiment of the present invention (the cutting direction and position are the same as Figure 3 ).

[0022] In the figure: 1: Rib layer; 11: Substrate; 12: Rib; 121: Fillet; 13: Gas inlet; 14: Gas outlet; 2: Groove layer; 21: Groove; 211: Arc transition structure; 22: Through groove; 23: Accommodation groove; 3: Chip layer; 31: Bottom plate; 32: Installation groove; 33: Protruding block; 34: Through hole; 4: Printed circuit board; 5: Chip; 6: Metal pin. Detailed implementation manners

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 like Figures 1-6 As shown, the flow channel structure of the thermal gas micro-flow sensor provided in this embodiment of the invention includes a rib layer 1, a groove layer 2, and a chip layer 3. The three-layer structure is fixedly connected by eight sets of detachable fasteners to ensure complete fit between the layers. In this embodiment, the detachable fasteners are, for example, screws and nuts.

[0025] See Figures 3-6 The rib layer 1 includes a substrate 11, a gas inlet 13 and a gas outlet 14 penetrating the substrate, and a rib 12 mounted and protruding from the substrate 11, with the rib 12 located between the gas inlet 13 and the gas outlet 14. In this embodiment, assuming the nominal thickness of the selected rib 12 is d0 and the nominal height is h0, to facilitate subsequent adjustments to the flow channel shape and size, multiple serialized rib layers 1 with different rib thicknesses d and / or different rib heights h are prepared during actual processing. The series values ​​of the rib thickness d are selected within the range of 0.8d0 to 1.2d0, and the series values ​​of the rib height h are selected within the range of 0.8h0 to 1.2h0. It is worth noting that the height of the rib 12 refers to its protrusion from the substrate 11.

[0026] In a specific example, the nominal thickness of rib 12 is d0 = 1.0 mm, and the height is h0 = 1.5 mm. In actual manufacturing, a series of rib layers with a height h of 1.5 mm and thickness d of 0.8, 0.9, 1.0, 1.1, and 1.2 mm are prepared. Of course, for each rib thickness, ribs of different heights can be manufactured separately, for example, a series of ribs with height h of 1.2, 1.5, and 1.8 mm.

[0027] The groove layer 2 is provided with a groove 21 for accommodating the rib 12, and a through groove 22 for ventilation is provided at the bottom of the groove 21. In this embodiment, assuming that the nominal width of the selected groove 21 is D0 and the nominal depth is H0, in order to facilitate subsequent adjustment of the flow channel shape and size, multiple serialized groove layers 2 with different groove widths D and / or different groove depths H are prepared during actual processing. The series values ​​of the groove width d are selected in the range of 0.8D0 to 1.2D0, and the series values ​​of the groove depth H are selected in the range of 0.8H0 to 1.2H0.

[0028] The thickness d of the rib plate and the width D of the groove satisfy the relationship: d ≤ D; see Figure 4 , when d = D, the cross-section of the flow channel formed after assembly is rectangular; see Figure 7 , when d < D, the cross-section of the flow channel formed after assembly is U-shaped. It should be noted that when adjusting the shape and size of the flow channel cross-section, it can be achieved by replacing the groove layer 2 with grooves 21 of different sizes, or by replacing the rib plate layer 1 with rib plates of different sizes, or by replacing both the groove layer 2 with grooves 21 of different sizes and the rib plate layer 1 with rib plates of different sizes simultaneously.

[0029] The chip layer 3 includes a bottom plate 31, and an installation groove 32 for installing a printed circuit board (PCB) and a chip is provided on the bottom plate 31. A through hole 34 for a metal pin to pass through is provided at the bottom of the installation groove 32.

[0030] See Figure 3 and Figure 4 As shown in

[0031] By replacing the rib plate layer 1 with different rib plate sizes and / or the groove layer 2 with different sizes, the adjustability of the cross-section shape and size of the flow channel is achieved. In this way, the combination of flow channel parameters with the best performance can be quickly found. Through the innovation of the mechanical structure, the present invention realizes the convenient adjustability of the flow channel performance, provides great flexibility for sensor research and development, shortens the research and development cycle, and reduces the iteration cost.

[0032] In this embodiment, sealing rings (not shown in the figure) are respectively provided on the contact planes between the rib plate layer 1 and the groove layer 2, and between the groove layer 2 and the chip layer 3 to achieve planar sealing. Preferably, multi-channel planar sealing is respectively adopted on the contact planes between the rib plate layer 1 and the groove layer 2, and between the groove layer 2 and the chip layer 3. For example, two sealing rings are arranged at intervals between every two adjacent layers.

[0033] In order to stabilize the airflow and minimize the influence on the airflow, in one example, see Figure 3 , Figure 5 and Figure 6 , arc transition structures 211 are provided on the two end walls in the length direction of the groove 21. On both sides in the length direction of one end of the rib plate 12背离基板11的一端, rounded corners 121 are provided. A relatively smooth transition structure is formed at the corner of the flow channel.

[0034] See Figure 3 and Figure 5 In one example, a protrusion 33 is provided on the contact surface between the chip layer 3 and the groove layer 2, and a mounting groove 32 is provided on the protrusion 33. The contact surface between the groove layer 2 and the chip layer 3 is provided with a receiving groove 23 for accommodating the protrusion 33, which can further improve the sealing performance, assembly convenience and accuracy.

[0035] In this embodiment, the rib 12 and the base plate 11 can be an integral structure or a detachable connection; no limitation is made here. In one example, see... Figure 8 As shown, if the rib 12 and the substrate 11 are detachably connected (e.g., tight-fitting plug-in, screw fixing connection, etc.), then only a series of ribs 12 need to be processed. The part of the rib 12 connected to the substrate 11 is the same. When different sizes of ribs are needed, only the ribs of the corresponding sizes need to be replaced. This will not be elaborated further here.

[0036] This embodiment also provides a flow channel structure design method for a thermal gas micro-flow sensor, which is used for designing the flow channel structure of the thermal gas micro-flow sensor, and includes the following steps: S1. Determine the required measurement parameters, including the type of gas to be measured, upstream and downstream pressures, flow measurement range, and gas density. and gas kinematic viscosity ; S2. Initial selection of flow channel parameters: initially select the cross-sectional shape of the flow channel as rectangular or U-shaped, and select a set of initial flow channel characteristic dimensions, including groove width D0, groove depth H0, rib thickness d0, and rib height h0. S3. Calculate the flow velocity and Reynolds number: Based on maximum mass flow rate Given the initially selected cross-sectional area S of the flow channel, calculate the maximum gas velocity:

[0037] Calculate the hydraulic diameter of the flow channel And calculate the Reynolds number: Determine if Re is less than 2000. If yes, proceed to step S4; otherwise, return to step S2 to reselect the flow channel parameters. S4. Fluid simulation verification: Use software such as Ansys or Comsol to establish a fluid dynamics model based on the flow channel parameters selected in step S2 to perform simulation, verify whether the gas flow in the flow channel is in a laminar state, and evaluate the flow stability. If it meets the requirements, proceed to step S5; otherwise, return to step S2 to reselect the flow channel parameters. S5. Machining and Assembly: Based on the simulated flow channel parameters, machine the rib layer and groove layer parts, and assemble them with the chip layer to form the flow channel structure. S6. Performance Testing and Iteration: Perform performance testing on the assembled sensors. If the performance does not meet the requirements, replace the rib layer or groove layer parts with different feature dimensions and retest until the optimal flow channel parameter combination D1, H1, d1, h1 that meets the performance requirements is obtained.

[0038] In this embodiment, the method for calculating the cross-sectional area S of the flow channel in step S3 is as follows: When the cross-section of the flow channel is rectangular, S = s × w, where s is the flow channel height, w is the flow channel width, and s = H - h, w = d = D; When the cross-section of the flow channel is U-shaped, S = (D - d) × (H - h).

[0039] In step S3, the hydraulic diameter The calculation method is as follows: When the cross-section of the flow channel is rectangular: When the cross-section of the flow channel is U-shaped: in The wetted perimeter of the flow channel cross-section. .

[0040] In preparation for the iteration, in step S5, multiple sets of serialized rib plate layers and groove layers are processed simultaneously. The series values ​​of rib plate thickness d are selected from 0.8d0 to 1.2d0, the series values ​​of rib plate height h are selected from 0.8h0 to 1.2h0, the series values ​​of groove width D are selected from 0.8D0 to 1.2D0, and the series values ​​of groove depth H are selected from 0.8H0 to 1.2H0.

[0041] In this embodiment, in step S4, a heat source is placed on the channel wall corresponding to the chip heating area in the middle of the flow channel in the fluid dynamics simulation model to simulate the chip's working state. Preferably, the length L of the flow channel satisfies: .

[0042] The flow channel structure obtained by the design method provided in this embodiment enables convenient and adjustable flow channel performance. Starting from an initial guess of parameters, the optimal flow channel geometry parameters are quickly located through fluid simulation and component replacement testing. The entire process is time-efficient and low-cost, fully demonstrating the significant advantages of this invention in accelerating sensor research and development iterations.

[0043] It should be noted that the U-shaped cross-section of the flow channel means that the shape of the cross-section is approximately U-shaped, and does not necessarily mean that it must be exactly the same as the shape of a "U". For example, it can also be described as having a "U"-shaped cross-section, which is not limited here.

[0044] Example 2 like Figure 9 and Figure 10 As shown, the thermal gas microflow sensor provided in this embodiment includes any of the flow channel junctions in embodiment one, as well as a printed circuit board 4, a chip 5, and a metal pin 6. The printed circuit board 4 is mounted within the mounting slot 32.

[0045] The thermal MEMS flow sensor chip 5 is mounted on the printed circuit board 4 or chip layer 3 by means of bonding, and is electrically connected to the printed circuit board 4 by gold wire or aluminum wire bonding.

[0046] One end of the metal pin 6 is connected to the printed circuit board 4, and the other end passes through the via 34. The final electrical signal is led out through the metal pin 6, and the root of the metal pin 6 is sealed by potting silicone rubber or epoxy resin. Here, the potting and the sealing rings between each layer together achieve the overall structural seal.

[0047] The thermal gas microflow sensor in this embodiment has a simple structure and assembly. The rib layer and groove layer are adjusted only in the size of the ribs and grooves. The parts are highly interchangeable and can be easily adjusted in terms of the cross-sectional shape and size of the flow channel.

[0048] Any aspects not described in detail in this embodiment are common knowledge or existing technology in the field.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that not every embodiment contains only one independent technical solution, and in the absence of conflict between solutions, the various technical features mentioned in each embodiment can be combined in any way to form other implementation methods that can be understood by those skilled in the art.

[0050] Furthermore, without departing from the scope of the present invention, modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, shall not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flow channel structure for a thermal gas microflow sensor, characterized in that, include: The rib layer includes a substrate, a gas inlet and a gas outlet penetrating the substrate, and a rib mounted on and protruding from the substrate, the rib being located between the gas inlet and the gas outlet; The grooved layer has a groove for accommodating the rib, and the bottom of the groove has a through groove for ventilation; The chip layer includes a base plate, the base plate having mounting slots for mounting printed circuit boards and chips, and the bottom of the mounting slots having through holes for metal pins to pass through. The rib layer, groove layer and chip layer are fixedly connected by detachable fasteners. The rib is inserted into the groove and has a first ventilation gap with both ends of the groove along its length. The rib has a second ventilation gap with the bottom of the groove. The mounting groove is opposite to the through groove. The gas inlet, gas outlet, second ventilation gap and the two first ventilation gaps are connected. The thickness d of the rib and the width D of the groove satisfy the relationship: d ≤ D; When d = D, the cross-section of the flow channel formed after assembly is rectangular; when d < D, the cross-section of the flow channel formed after assembly is U-shaped. The shape and size of the flow channel cross-section can be adjusted by replacing rib layers with different rib sizes and / or groove layers with different sizes.

2. The flow channel structure according to claim 1, characterized in that: At least one sealing ring is provided on the contact plane between the rib layer and the groove layer, and on the contact plane between the groove layer and the chip layer.

3. The flow channel structure according to claim 1, characterized in that: The two end walls of the groove along its length are provided with arc transition structures; The rib has rounded corners on both sides along its length, at one end away from the base plate.

4. The flow channel structure according to claim 1, characterized in that: A protrusion is provided on the contact surface between the chip layer and the groove layer, and the mounting groove is disposed on the protrusion; The contact surface between the groove layer and the chip layer is provided with a receiving groove for accommodating the protrusion.

5. A method for designing the flow channel structure of a thermal gas microflow sensor, used for designing the flow channel structure according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Determine the required measurement parameters, including the type of gas to be measured, upstream and downstream pressures, flow measurement range, and gas density. and gas kinematic viscosity ; S2. Initial selection of flow channel parameters: initially select the cross-sectional shape of the flow channel as rectangular or U-shaped, and select a set of initial flow channel characteristic dimensions, including groove width D0, groove depth H0, rib thickness d0, and rib height h0. S3. Calculate the flow velocity and Reynolds number: Based on maximum mass flow rate Given the initially selected cross-sectional area S of the flow channel, calculate the maximum gas velocity: Calculate the hydraulic diameter of the flow channel And calculate the Reynolds number: Determine if Re is less than 2000. If yes, proceed to step S4; otherwise, return to step S2 to reselect the flow channel parameters. S4. Fluid simulation verification: Based on the flow channel parameters selected in step S2, establish a fluid dynamics model for simulation to verify whether the gas flow in the flow channel is in a laminar state and evaluate the flow stability. If it meets the requirements, proceed to step S5; otherwise, return to step S2 to reselect the flow channel parameters. S5. Machining and Assembly: Based on the simulated flow channel parameters, machine the rib layer and groove layer parts, and assemble them with the chip layer to form the flow channel structure. S6. Performance Testing and Iteration: Perform performance testing on the assembled sensors. If the performance does not meet the requirements, replace the rib layer or groove layer parts with different feature dimensions and retest until the optimal flow channel parameter combination D1, H1, d1, h1 that meets the performance requirements is obtained.

6. The design method according to claim 5, characterized in that: In step S5, multiple sets of serialized rib plate layers and groove layer parts are processed simultaneously. The series values ​​of rib plate thickness d are selected from 0.8d0 to 1.2d0, the series values ​​of rib plate height h are selected from 0.8h0 to 1.2h0, the series values ​​of groove width D are selected from 0.8D0 to 1.2D0, and the series values ​​of groove depth H are selected from 0.8H0 to 1.2H0.

7. The design method according to claim 5, characterized in that: In step S3, the cross-sectional area S of the flow channel is calculated as follows: When the cross-section of the flow channel is rectangular, S = s × w, where s is the flow channel height, w is the flow channel width, and s = H - h, w = d = D; When the cross-section of the flow channel is U-shaped, S = (D - d) × (H - h).

8. The design method according to claim 7, characterized in that: In step S3, the hydraulic diameter The calculation method is as follows: When the cross-section of the flow channel is rectangular: When the cross-section of the flow channel is U-shaped: in The wetted perimeter of the flow channel cross-section. .

9. The design method according to claim 5, characterized in that: In step S4, a heat source is placed on the flow channel wall in the middle of the flow channel corresponding to the chip heating area in the fluid dynamics simulation model to simulate the working state of the chip. The length L of the flow channel satisfies: .

10. A thermal gas microflow sensor, characterized in that, Includes the flow channel structure as described in any one of claims 1 to 4; A printed circuit board is installed in the mounting slot; The chip is mounted on the printed circuit board or chip layer and is electrically connected to the printed circuit board by gold or aluminum wire bonding. The metal pin has one end connected to the printed circuit board and the other end passing through the via, with its root sealed with potting compound.

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