Thermal flow sensor

Abstract

The present application belongs to the technical field of flow sensors, and specifically provides a thermal flow sensor, including a shell, a flow tube, two heating resistors, a first temperature control module and a second temperature control module; the flow tube is arranged in the shell and in contact with the shell; the two heating resistors are arranged on the flow tube at intervals along the flow direction of the fluid; the first temperature control module and the second temperature control module are connected to the shell, and the first temperature control module is used to control the heating resistor to maintain a first temperature; the second temperature control module is used to control the shell to maintain a second temperature, and make the second temperature lower than the first temperature; the embodiments of the present application can solve the technical problems existing in the prior art that the thermal flow sensor requires complex algorithms to correct the measurement results and that the high-temperature corrosive gas corrodes the device more seriously.

Description

Technical Field

[0001] The present application belongs to the technical field of flow sensors, and in particular relates to a thermal flow sensor. Background Art

[0002] The thermal flow sensor includes an upstream resistor and a downstream resistor arranged on a capillary tube. When measuring the flow rate, the thermal flow sensor supplies power to the upstream resistor and the downstream resistor, causing the upstream resistor and the downstream resistor to heat up. The fluid in the capillary tube flows through the upstream resistor and the downstream resistor, taking away some heat. The heat change of the upstream resistor and the downstream resistor is manifested as a change in the electrical signal, and the flow rate is calculated based on the change in the electrical signal. The upstream resistor and the downstream resistor exchange heat with the fluid while also exchanging heat with the environment. The temperature difference between the ambient temperature and the upstream resistor and the downstream resistor is constantly changing, resulting in a constantly changing influence of the ambient temperature on the upstream resistor and the downstream resistor, which makes the measurement error of the thermal flow sensor large. Therefore, a complex algorithm is required to correct the measurement result. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a thermal flow sensor to solve the technical problem in the prior art that the thermal flow sensor requires a complex algorithm to correct the measurement result.

[0004] To achieve the above-mentioned purpose, an embodiment of the present application provides a thermal flow sensor, including a shell, a flow tube, two heating resistors, a first temperature control module and a second temperature control module; the flow tube is arranged in the shell and in contact with the shell; the two heating resistors are arranged at intervals on the flow tube along the flow direction of the fluid; the first temperature control module and the second temperature control module are connected to the shell, and the first temperature control module is used to control the heating resistor to maintain a first temperature; the second temperature control module is used to control the shell to maintain a second temperature, and make the second temperature lower than the first temperature.

[0005] The beneficial effects of this embodiment are as follows: the second temperature control module controls the temperature of the shell to be lower than the temperature of the heating resistor (the first temperature), so that the second temperature and the first temperature maintain a constant temperature difference, the fluid exchanges heat with the shell before flowing through the upstream heating resistor, so that the fluid temperature is lower than the upstream heating resistor, and the fluid is heated to the first temperature by the upstream heating resistor when flowing through the upstream heating resistor, so that the change of the electrical signal of the upstream heating resistor is more obvious; the fluid is higher than the shell temperature (the second temperature) after being heated by the upstream heating resistor, so that the heat exchange between the upstream heating resistor and the downstream heating resistor and the environment in the shell is more; the temperature of the fluid is higher than the second temperature when flowing through the downstream heating resistor, and the temperature difference between the fluid and the downstream heating resistor is less than the temperature difference between the fluid and the upstream heating resistor, so the downstream heating resistor needs less power to maintain the first temperature, so that the electrical signals of the upstream heating resistor and the downstream heating resistor are different, and a relationship is established with the flow size in the flow channel according to the difference in the electrical signal. Since the temperature difference between the first temperature and the second temperature is kept constant, a stable relationship can be established between the electrical signal and the flow size, avoiding the correction of the relationship caused by the shell temperature fluctuation caused by the environment.

[0006] In some embodiments, the first temperature control module includes two Wheatstone bridges, the Wheatstone bridge includes a first bridge arm and a second bridge arm, the first bridge arm includes the heating resistor, the second bridge arm includes at least two temperature-controlled resistors in parallel, and each temperature-controlled resistor is connected in series with a switch; the temperature-controlled resistor and the heating resistor form a voltage divider circuit, and the resistance value of each temperature-controlled resistor is different; the switch is used to switch different temperature-controlled resistors to be connected to the first bridge arm to switch the value of the first temperature.

[0007] The beneficial effect of this embodiment is that by switching temperature-controlled resistors with different resistance values, the heating resistor can be controlled to maintain different first temperatures to be suitable for different gases. When measuring corrosive gases, controlling the heating resistor to maintain a low temperature can reduce the temperature of the corrosive gas and reduce corrosion to the device; when measuring non-corrosive gases, controlling the housing to maintain a normal temperature can reduce the power required for heat exchange between the second temperature control module and the housing.

[0008] In some embodiments, the second temperature control module includes a heat exchange component and a temperature sensor communicatively connected to the heat exchange component, the heat exchange component is connected to the outer wall surface of the shell, the heat exchange component is used to exchange heat with the shell at a basic power to control the temperature of the shell; the temperature sensor is connected to the inner wall surface of the shell to sense the temperature of the shell.

[0009] The beneficial effects of this embodiment are: the temperature of the shell can be sensed in real time by the temperature sensor, and the heat exchange component can be adjusted accordingly according to the changes in the sensed shell temperature to reduce the temperature fluctuation of the shell and make the temperature of the shell more stable.

[0010] In some embodiments, the second temperature control module also includes a first storage unit, a first information acquisition unit and a first power adjustment unit, the first storage unit is used to store a first preset chart; the first information acquisition unit is used to collect a first parameter, the first power adjustment unit is used to obtain a first compensation power according to the first preset chart and the first parameter, the first power adjustment unit is used to obtain a first compensation power according to the first preset chart and the collected first parameter, and the first power adjustment unit is also used to control the heat exchange component to exchange heat with the shell at the sum of the basic power and the first compensation power.

[0011] The beneficial effects of this embodiment are as follows: due to different fluid flow rates, the amount of heat carried by the fluid after passing through the heating resistor is different, and the heat exchange rate between the fluid through the flow tube and the shell after passing through the downstream heating resistor is different. The heat exchange component needs to adjust the power of the heat exchange component according to the heat exchange rate between the flow tube and it; the power of the heat exchange component is adjusted by combining the first compensation power with the basic power, so that the heat exchange component can respond in time and change the power when the shell temperature changes, so that the shell can stably maintain the second temperature.

[0012] In some embodiments, the second temperature control module also includes a second storage unit, a second information acquisition unit and a second power adjustment unit, the second storage unit is used to store a second preset chart; the second information acquisition unit is used to collect second parameters, the second power adjustment unit is used to obtain a second compensation power according to the second preset chart and the second parameters, and the second power adjustment unit is also used to control the heat exchange component to exchange heat with the shell at the sum of the basic power and the second compensation power.

[0013] The beneficial effects of this embodiment are as follows: since the temperature sensor has a response time, controlling the heat exchange component based only on the temperature sensed by the temperature sensor will cause the system response time to be delayed and slow, resulting in inaccurate temperature control of the shell; the power of the heat exchange component is adjusted by combining the second compensation power with the basic power, so that the heat exchange component can respond in time and change the power when the shell temperature changes, thereby allowing the shell to stably maintain the second temperature.

[0014] In some embodiments, the heat exchange component includes a semiconductor refrigerator, which includes a first end and a second end, the first end and the second end have different temperatures, one of the second end and the first end is connected to the shell, and the other of the second end and the first end extends outside the shell and is used to connect to a structural member outside the shell and exchange heat.

[0015] The beneficial effects of this embodiment are that the second end and the first end of the semiconductor refrigerator can both generate heat and cool. When the shell temperature is higher than the second temperature, the semiconductor refrigerator can cool the shell. When the shell temperature is lower than the second temperature, the semiconductor refrigerator can heat the shell. This facilitates precise control of the shell temperature and is suitable for different working environments.

[0016] In some embodiments, the heat exchange component also includes a heat spreader; the heat spreader is connected to the end of the semiconductor refrigerator facing away from the shell; the heat exchange component also includes a plurality of first ribs and second ribs, the first ribs are connected to the side of the heat spreader facing away from the semiconductor refrigerator and are arranged at an angle to the heat spreader; the second ribs are connected to the end of each of the first ribs facing away from the heat spreader, and the second ribs are provided with a plurality of heat dissipation holes; the second ribs are connected to the structural member.

[0017] The beneficial effects of this embodiment are: arranging a heat spreader and a first fin between the structural member and the shell can improve the thermal conductivity, increase the heat dissipation area, accelerate the heat dissipation of the semiconductor refrigerator, and improve the cooling effect of the semiconductor refrigerator on the shell; arranging the second fin can further increase the heat dissipation area of ​​the semiconductor refrigerator, and the heat dissipation holes can make the external airflow contact with the first fin, thereby enhancing convective heat exchange.

[0018] In some embodiments, the heat exchange component also includes a heat spreader; the heat spreader is connected to one end of the semiconductor refrigerator facing away from the shell; the heat exchange component also includes a plurality of heat dissipation protrusions, and the heat dissipation protrusions are connected to a side of the heat spreader facing away from the semiconductor refrigerator.

[0019] The beneficial effect of this embodiment is that the provision of the heat dissipation protrusions can increase the heat dissipation area of ​​the heat spreader, accelerate the heat dissipation of the semiconductor refrigerator, and improve the cooling effect of the semiconductor refrigerator on the shell.

[0020] In some embodiments, the semiconductor refrigerator includes at least three insulating heat-conducting plates and at least two layers of Peltier, and the Peltier is sandwiched between two adjacent layers of the insulating heat-conducting plates.

[0021] The beneficial effect of this embodiment is that the provision of multiple layers of Peltier can increase the power of the semiconductor refrigerator and improve the heat exchange efficiency with the shell.

[0022] In some embodiments, the thermal flow sensor further includes a heat insulating member, the heat exchange component and the heat insulating member form a heat exchange cavity, and the shell is disposed in the heat exchange cavity and is attached to the heat exchange component.

[0023] The beneficial effects of this embodiment are: arranging the shell in the heat exchange cavity can reduce the heat dissipation of the shell to the external environment, which is beneficial to controlling the shell to maintain a stable temperature; when the shell is connected to other structures of the thermal flow sensor, or when the shell is connected to other structures in the flow controller, connecting through the insulation board can reduce the heat exchange between the shell and other structures connected to the shell, reduce the heat exchange between the heat exchange component and other structures connected to the shell, and make the temperature of the shell and other structures connected to the shell more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of the interior of a housing of a thermal flow sensor provided in an embodiment of the present application;

[0026] Figure 2 An exploded diagram of a thermal flow sensor provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of the connection between the temperature control circuit board provided in the embodiment of the present application and the upstream resistor, the downstream resistor and the temperature sensor;

[0028] Figure 4 A schematic diagram of a Wheatstone bridge provided in an embodiment of the present application;

[0029] Figure 5 A flow chart of power regulation of a heat exchange component provided in an embodiment of the present application;

[0030] Figure 6 Schematic diagram of the heat exchange assembly provided in the embodiment of the present application Figure 1 ;

[0031] Figure 7 A schematic diagram of the connection between the heat sink and the second rib provided in an embodiment of the present application;

[0032] Figure 8 Schematic diagram of the semiconductor refrigerator provided in the embodiment of the present application Figure 1 ;

[0033] Fig. 9Schematic diagram of the heat exchange assembly provided in the embodiment of the present application Figure 2 ;

[0034] Fig.10 Schematic diagram of the heat exchange assembly provided in the embodiment of the present application Figure 3

[0035] Fig.11 Schematic diagram of the semiconductor refrigerator provided in the embodiment of the present application Figure 2 .

[0036] Among them, the reference numerals in the figure are:

[0037] 100. Thermal flow sensor;

[0038] 10. housing; 11. groove;

[0039] 20. Flow channel tube;

[0040] 30. Upstream resistance;

[0041] 40. Downstream resistance;

[0042] 50. Temperature control circuit board; 51. Temperature control PID circuit; 52. First temperature control module; 53. Wheatstone bridge; 531. First bridge arm; 532. Second bridge arm; 5321. Temperature control resistor; 533. Voltage divider resistor;

[0043] 60. Second temperature control module; 61. Temperature sensor; 62. Heat exchange assembly; 621. Cold plate; 622. Semiconductor refrigerator; 6221. Insulated heat conductive plate; 6222. PN junction; 623. Heat spreader; 624. First fin; 625. Second fin; 626. Heat dissipation hole; 627. Heat dissipation protrusion; 628. Sensor housing; 70. Thermal insulation. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0046] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0048] An embodiment of the present application provides a thermal flow sensor for measuring the flow rate of a fluid. The thermal flow sensor can be used in a mass flow controller. The fluid can be a gas, a liquid or other fluid. The embodiment of the present application takes gas as an example for explanation.

[0049] The present application embodiment provides a thermal flow sensor, please refer to Figures 1 to 3 The thermal flow sensor 100 includes a shell 10, a flow tube 20, two heating resistors, a first temperature control module 52 and a second temperature control module 60; the flow tube 20 is arranged in the shell 10 and contacts the shell 10; the two heating resistors are arranged at intervals on the flow tube 20 along the flow direction of the fluid; the first temperature control module 52 and the second temperature control module 60 are connected to the shell 10, and the first temperature control module 52 is used to control the heating resistor to maintain a first temperature; the second temperature control module 60 is used to control the shell 10 to maintain a second temperature and make the second temperature lower than the first temperature.

[0050] The shell 10 is used to isolate the flow tube 20 and the heating resistor from the external environment to provide a stable measurement environment; the shell 10 is in contact with the flow tube 20 for heat exchange, and the shell 10 is also used to exchange heat with the gas through the flow tube 20; optionally, the shell 10 is a high thermal conductivity material with a thermal conductivity coefficient greater than 50W / (mK), and specifically aluminum, copper and other materials can be selected.

[0051] The flow tube 20 is used to connect to the main pipeline of the gas, so that part of the gas in the main pipeline flows through the flow tube 20; the flow tube 20 is in contact with the shell 10 at both upstream and downstream positions to facilitate heat exchange between the shell 10 and the gas.

[0052] The two heating resistors are located between the two positions where the flow tube 20 contacts the shell 10. The heating resistors are used to heat the gas in the flow tube 20 to the same temperature as the heating resistors. The heating resistor close to the upstream of the flow tube 20 is the upstream resistor 30, and the heating resistor close to the downstream of the flow tube 20 is the downstream resistor 40. Optionally, the two heating resistors are symmetrical about the middle position of the flow tube 20, and the heating resistors are heating resistance wires wound on the flow tube 20.

[0053] Optionally, the first temperature control module 52 includes an upstream circuit and a downstream circuit for controlling the temperature of the upstream resistor 30 and the temperature of the downstream resistor 40 respectively, the upstream circuit is connected to the upstream resistor 30, and the downstream circuit is connected to the downstream resistor 40; the voltage signal of the heating resistor is fed back to the next-level component of the thermal flow sensor 100 through the upstream circuit and the downstream circuit for calculation.

[0054] The first temperature is a preset target temperature of the heating resistor, and the two heating resistors maintain the same target temperature. The second temperature is a preset target temperature of the housing 10, that is, the ambient temperature of the gas when it flows through the housing 10. Different first temperatures and second temperatures can be set for measuring different gases, but during one measurement, the values ​​of the set first temperature and second temperature remain unchanged.

[0055] The temperature difference between the first temperature and the second temperature is selected according to the application control scenario of the flow sensor. Optionally, for a flow sensor applied in the semiconductor field, the temperature difference range of the first temperature and the second temperature is set to 50°C-75°C.

[0056] The value of the first temperature is related to the type of gas. Non-corrosive gases are less sensitive to high temperatures, so the heating resistor can be maintained at a higher operating temperature, that is, the first temperature can be higher. According to the temperature difference between the second temperature and the first temperature, the second temperature can be maintained constant near normal temperature (22°C); optionally, for non-corrosive gases, the second temperature is 20°C-25°C.

[0057] Corrosive gases are highly sensitive to high temperatures, so the first temperature is required to be relatively low to prevent the equipment from reacting with the corrosive gases at high temperatures and shortening its service life. Based on the temperature difference between the second temperature and the first temperature, the second temperature needs to be maintained at a lower temperature; optionally, for corrosive gases, the second temperature is 5°C-10°C.

[0058] The working process of this embodiment is as follows: the second temperature control module 60 controls the temperature of the shell 10 to be maintained near the second temperature, so that the second temperature and the first temperature maintain a relatively stable temperature difference; the fluid first exchanges heat with the shell 10 before flowing through the upstream resistor 30, and the fluid temperature reaches near the second temperature; when the fluid flows through the upstream resistor 30, it is heated to the first temperature by the upstream resistor 30. Since the temperature difference between the first temperature and the second temperature is large, the power required for the upstream resistor 30 to maintain the first temperature is greater, so that the electrical signal change of the upstream resistor 30 is more obvious. After the fluid is heated by the upstream resistor 30, the temperature reaches the first temperature and is higher than the second temperature; after the fluid flows through the upstream resistor 30, the fluid exchanges heat with the environment in the shell 10 between the upstream resistor 30 and the downstream resistor 40 , the fluid temperature drops and is lower than the first temperature. Affected by factors such as flow velocity and flow distance, the fluid temperature is difficult to drop to the second temperature, that is, the fluid temperature is lower than the first temperature and higher than the second temperature at this time; when the fluid flows through the downstream resistor 40, the temperature reaches the first temperature after being heated by the downstream resistor 40; before the fluid is heated by the upstream resistor 30 and the downstream resistor 40, the temperature difference between the fluid and the downstream resistor 40 is lower than the temperature difference between the fluid and the upstream resistor 30, so the heat exchange between the downstream resistor 40 and the fluid is less, and the power required for the downstream resistor 40 to maintain the first temperature is smaller, so that the electrical signals of the upstream resistor 30 and the downstream resistor 40 are different; a relationship is established based on the difference in the electrical signal and the flow size in the flow channel tube 20, that is, the flow is positively correlated with the difference in the electrical signal. Since the temperature difference between the first temperature and the second temperature remains relatively constant, a stable relationship can be established between the electrical signal and the flow size, avoiding interference with the relationship caused by the temperature fluctuation of the shell 10 due to changes in the external environment and a negative impact on the flow measurement accuracy.

[0059] The shell 10 is made of high thermal conductivity material, which can quickly exchange heat with the gas through the flow tube 20, so that the temperature of the gas quickly changes to the second temperature when entering the shell 10; the shell 10 can have high thermal conductivity by using materials such as aluminum and copper. For non-corrosive gases, the temperature range of the second temperature is near room temperature, which can reduce the power output of the second temperature control module 60 when exchanging heat with the shell. For corrosive gases, the second temperature is controlled in the range of 5°C-10°C, which can control the first temperature to maintain a relatively low temperature on the basis of maintaining the temperature difference between the first temperature and the second temperature, thereby reducing the corrosion of the flow tube 20 by the corrosive gas.

[0060] In some embodiments, please refer to Figure 3 and Figure 4The first temperature control module 52 includes two Wheatstone bridges 53. The Wheatstone bridge 53 provided in this embodiment includes a first bridge arm 531 and a second bridge arm 532. The first bridge arm 531 includes a heating resistor, and the second bridge arm 532 includes at least two parallel temperature-controlled resistors 5321. Each temperature-controlled resistor 5321 is connected in series with a switch; the temperature-controlled resistor 5321 and the heating resistor form a voltage-dividing circuit, and the resistance values ​​of the temperature-controlled resistors 5321 are different; the switch is used to switch different temperature-controlled resistors 5321 to be connected to the first bridge arm 531, control the heating resistor in the first bridge arm 531 to be equal to the resistance value of different temperature-controlled resistors 5321, and control the heating resistors to maintain different resistance values ​​to switch the value of the first temperature.

[0061] The temperature-controlled resistor 5321 on the second bridge arm 532 is used to control the temperature of the heating resistor to remain constant. The temperature-controlled resistors 5321 with different resistance values ​​are used to control the heating resistor to maintain different temperatures. After the switch of the temperature-controlled resistor 5321 is closed, the temperature-controlled resistor 5321 is connected to the heating resistor, and the heating resistor is controlled to maintain the same resistance as the temperature-controlled resistor 5321. Different resistance values ​​of the heating resistors correspond to different temperatures. When the two switches are closed at the same time, the heating resistor is connected to the two temperature-controlled resistors 5321 in the second bridge arm 532. At this time, the resistance of the heating resistor is controlled to be equal to the resistance of the two temperature-controlled resistors 5321 in parallel.

[0062] It can be understood that there are at least two Wheatstone bridges 53 , and the two heating resistors are respectively arranged in two different Wheatstone bridges 53 .

[0063] It can be understood that the Wheatstone bridge 53 further includes a third bridge arm and a fourth bridge arm. The third bridge arm and the fourth bridge arm each include a voltage-dividing resistor 533 , and the resistance values ​​of the two voltage-dividing resistors 533 are equal.

[0064] The Wheatstone bridge 53 is a circuit structure used to accurately measure the resistance value of an unknown resistor. The third bridge arm and the fourth bridge arm are ratio arms of the Wheatstone bridge 53. The resistance value of the voltage divider resistor 533 in the third bridge arm and the fourth bridge arm can control the ratio of the heating resistor in the first bridge arm 531 to the temperature control resistor 5321 in the second bridge arm 532.

[0065] The beneficial effect of this embodiment is that by switching the temperature-controlled resistor 5321 with different resistance values, the heating resistor can be controlled to maintain different first temperatures to be suitable for different gases. When measuring corrosive gases, controlling the heating resistor to maintain a low temperature can reduce the temperature of the corrosive gas and reduce corrosion to the device; when measuring non-corrosive gases, controlling the heating resistor to maintain a normal temperature can reduce the power required for refrigeration.

[0066] In some embodiments, please refer to Figure 2The second temperature control module 60 includes a heat exchange component 62 and a temperature sensor 61 that is communicatively connected to the heat exchange component 62. The heat exchange component 62 is connected to the outer wall surface of the shell 10. The heat exchange component 62 is used to exchange heat with the shell 10 at a basic power to control the temperature of the shell 10; the temperature sensor 61 is connected to the inner wall surface of the shell 10 to sense the temperature of the shell 10.

[0067] The heat exchange component 62 may include a heater and a cooler, or may include one of the heater and the cooler; the heat exchange component 62 is specifically configured according to the difference between the second temperature and the external environment to heat or cool the housing 10.

[0068] The basic power is the output power of the heat exchange component 62 . The basic power changes according to the difference between the temperature sensed by the temperature sensor 61 and the second temperature. The second temperature control module 60 can collect the value of the basic power.

[0069] The second temperature control module 60 obtains the output power of the heat exchange component 62 according to the difference between the temperature sensed by the temperature sensor 61 and the second temperature.

[0070] Optionally, the temperature sensor 61 is a thermistor, including a high-precision negative temperature coefficient thermistor or a positive temperature coefficient thermistor, with a measurement accuracy of ±1K (Kelvin). The thermistor is connected to the temperature control circuit board 50, and the temperature control circuit board 50 is used to obtain the voltage division value of the thermistor. The resistance value and temperature of the thermistor can be obtained through the voltage divided by the thermistor.

[0071] The beneficial effects of this embodiment are: the temperature of the shell 10 can be sensed in real time by the temperature sensor 61, and the heat exchange component 62 can be adjusted accordingly according to the sensed temperature change of the shell 10 to reduce the temperature fluctuation of the shell 10 and make the temperature of the shell 10 more stable.

[0072] In some embodiments, the second temperature control module 60 also includes a first storage unit, a first information acquisition unit and a first power adjustment unit, the first storage unit is used to store a first preset chart; the first information acquisition unit is used to collect a first parameter, the first power adjustment unit is used to obtain a first compensation power according to the first preset chart and the collected first parameter, the first power adjustment unit is used to obtain a first compensation power according to the first preset chart and the collected first parameter, and the first power adjustment unit is also used to control the heat exchange component 62 to exchange heat with the shell 10 at the sum of the basic power and the first compensation power.

[0073] When the gas flow rate in the flow channel tube 20 is large, the gas takes away more heat from the heating resistor per unit time. In order to keep the temperature of the heating resistor constant, the output power needs to be increased. In order to maintain the heat balance in the shell 10, make the heat of the gas entering and exiting the shell 10 equal, and reduce the impact of the gas heat on the original system, that is, not to take away the heat by the gas flowing out of the shell 10, it is necessary to quickly cool the temperature of the gas in the downstream of the flow channel tube 20 through the heat exchange component 62, so that the temperature of the gas when it flows out of the shell 10 is the same as the temperature of the gas when it flows into the shell 10. Therefore, it is necessary to perform additional power compensation on the heat exchange component 62 according to the power of the heating resistor to increase the power of the heat exchange component 62 and enable the heat exchange component 62 to quickly exchange heat with the shell 10, so that the shell 10 can be cooled quickly, that is, the first compensation power is used to compensate the basic power.

[0074] It can be understood that the first power regulating unit is connected to the heat exchange assembly 62. Optionally, the first storage unit includes a memory, and the first power regulating unit includes a processor and a controller.

[0075] It can be understood that the first preset chart is the relationship between the first parameter and the first compensation power; the first compensation power is obtained based on the heat exchange between the shell 10 and the flow tube 20, the heat exchange between the shell 10 and the flow tube 20 is related to the first parameter, and the first parameter is related to the voltage value of the upstream resistor 30, the voltage value of the downstream resistor 40, the resistance value of the upstream resistor 30, and the resistance value of the downstream resistor 40.

[0076] Optionally, the first preset chart is obtained by the following method: controlling the temperature of the flow tube 20 at the position where the gas flows out of the shell 10 to remain unchanged, measuring multiple sets of data corresponding to different gas flow rates, each set of data including the first compensation power, the voltage value of the upstream resistor 30, the voltage value of the downstream resistor 40, the resistance value of the upstream resistor 30, and the resistance value of the downstream resistor 40; fitting the relationship between the first compensation power and the first parameter according to the multiple sets of data to obtain the first preset chart.

[0077] The beneficial effects of this embodiment are as follows: due to different flow rates of the fluid, the amount of heat carried by the fluid after passing through the heating resistor is different, and the amount of heat exchange between the fluid through the flow tube 20 and the shell 10 after passing through the downstream resistor 40 is different. The heat exchange component 62 needs to adjust the power of the heat exchange component 62 according to the heat exchange between the flow tube 20 and it; the power of the heat exchange component 62 is adjusted by combining the first compensation power with the basic power, so that the shell 10 can stably maintain the second temperature.

[0078] In some embodiments, please refer to Figure 2The second temperature control module 60 also includes a second storage unit, a second information acquisition unit and a second power adjustment unit. The second storage unit is used to store a second preset chart; the second information acquisition unit is used to collect second parameters, and the second power adjustment unit is used to obtain a second compensation power according to the second preset chart and the collected second parameters. The second power adjustment unit is also used to control the heat exchange component 62 to exchange heat with the shell 10 at the sum of the basic power and the second compensation power.

[0079] Since the response time of the temperature sensor 61 is relatively long when performing temperature measurement, adjustment based only on the temperature change value of the temperature sensor 61 will cause the system response time to lag and be slow, resulting in inaccurate temperature control. Therefore, it is necessary to compensate for the time delay, that is, use the second compensation power to compensate the basic power.

[0080] The second power regulating unit is connected to the heat exchange assembly 62. Optionally, the second storage unit includes a memory, and the second power regulating unit includes a processor and a controller. Optionally, the second storage unit and the first storage unit use common hardware, and the second power regulating unit and the first power regulating unit use common hardware.

[0081] The second preset chart is the relationship between the second parameter and the second compensation power; the second compensation power is obtained according to the response time of the temperature sensor 61 sensing the temperature, the heat exchange between the shell 10 and the flow channel tube 20 is related to the second parameter, the second parameter is related to the temperature sensed by the temperature sensor 61 and the predicted temperature, and the predicted temperature is the temperature sensed by the temperature sensor 61 after the response time under the power of the current heat exchange component 62. The second preset chart is used to show the corresponding relationship between the difference between the predicted temperature and the temperature sensed by the temperature sensor 61 and the second compensation power.

[0082] Optionally, the predicted temperature is obtained by the following method: fitting the relationship between the temperature sensed by the temperature sensor 61, the current power of the heat exchange component 62, and time to obtain a third preset chart, the third chart is used to display the correspondence between the power of the heat exchange component 62 and the temperature sensed by the temperature sensor 61 at each subsequent moment, and the temperature sensed by the temperature sensor 61 after the response time is predicted based on the current power of the heat exchange component 62, the response time of the temperature sensor 61, and the third preset chart; the third preset chart and the response time of the temperature sensor 61 are stored in the second storage unit.

[0083] Optionally, the first compensation power and the second compensation power compensate the basic power input through feedforward control to achieve fast and accurate temperature control. Feedforward control is a control system that works according to the compensation principle based on the change of disturbance or given value.

[0084] It can be understood that the basic power can be corrected by the first compensation power and the second compensation power at the same time, or the basic power can be corrected by only the first compensation power or the second compensation power.

[0085] The beneficial effects of this embodiment are as follows: since the temperature sensor 61 has a response time, controlling the heat exchange component 62 based only on the temperature sensed by the temperature sensor 61 will cause the system response time to be delayed and slow, resulting in inaccurate temperature control of the shell 10; by adjusting the power of the heat exchange component 62 in combination with the second compensation power and the basic power, the influence of the response time of the temperature sensor 61 on the power of the heat exchange component 62 can be compensated, so that the shell 10 can stably maintain the second temperature.

[0086] In some embodiments, please refer to Figure 2 The heat exchange component 62 includes a semiconductor refrigerator 622, which includes a first end and a second end. The temperature of the first end is different from that of the second end. One of the second end and the first end is connected to the shell 10, and the other of the second end and the first end extends outside the shell 10 and is used to connect to a structural member outside the shell 10 and exchange heat.

[0087] It can be understood that the first end and the second end of the semiconductor refrigerator 622 both have two states, heating and cooling. The two states of the first end and the second end can be switched according to the direction of the current. When the first end is heating, the second end is cooling; when the first end is cooling, the second end is heating. When the temperature of the shell 10 is lower than the second temperature, the end of the semiconductor refrigerator 622 connected to the shell 10 is heated to increase the temperature of the shell 10; when the temperature of the shell 10 is higher than the second temperature, the end of the semiconductor refrigerator 622 connected to the shell 10 is cooled to cool the shell 10. Optionally, the power supply of the semiconductor refrigerator 622 is an H-bridge circuit power supply whose electrodes can be flipped to provide positive and negative voltages; the H-bridge is a typical DC motor control circuit whose circuit shape is similar to the letter H. The H-bridge circuit can reverse the current at both ends of the load or output terminal to which it is connected. Optionally, the semiconductor refrigerator 622 uses two synchronous buck circuits with complementary drives, which can obtain dual power supplies from a single power supply, while making the single positive power supply more efficient. Please refer to Figure 3 and Figure 5 Optionally, a temperature control PID (Proportional Integral Derivative) circuit 51 is provided on the temperature control circuit board 50. The temperature control PID circuit 51 is used to control the power of the semiconductor refrigerator 622 (Thermoelectric cooler, TEC) so that the difference T3 between the temperature T1 sensed by the temperature sensor 61 and the second temperature T2 is within a preset range.

[0088] Optionally, the semiconductor cooler 622 is adhered to the housing 10 by an adhesive with high thermal conductivity and low heat capacity. Optionally, the housing 10 includes two opposite mounting surfaces, the semiconductor cooler 622 is mounted on one of the mounting surfaces outside the housing 10, and the flow channel tube 20 and the temperature sensor 61 are mounted on the other mounting surface inside the housing 10.

[0089] Optionally, the semiconductor cooler 622 is bonded and fixed with the same material as the shell 10 around the semiconductor cooler 622, and then bonded to the shell 10 to achieve good sealing and better connection between the semiconductor cooler 622 and the flow sensor.

[0090] Optional, please refer to Figure 6 and Figure 8 The semiconductor cooler 622 includes two insulating heat-conducting plates 6221 and a Peltier layer sandwiched between the two insulating heat-conducting plates 6221. The Peltier layer includes a plurality of PN junctions 6222, and the PN junctions 6222 are connected together through connecting sheets.

[0091] The beneficial effects of this embodiment are: the second end or the first end connected to the shell 10 can be used for heating and cooling, and the semiconductor refrigerator 622 is set to cool the shell 10 when the temperature of the shell 10 is higher than the second temperature, and to heat the shell 10 when the temperature of the shell 10 is lower than the second temperature, so as to facilitate precise control of the temperature of the shell 10 and be suitable for different working environments; the semiconductor refrigerator 622 has a good cooling effect and can ensure that there is a sufficient temperature difference between the shell 10 and the heating resistor.

[0092] In some embodiments, please refer to Figure 2 , Figure 7 and Fig. 9 The heat exchange component 62 also includes a heat spreader 623; the heat spreader 623 is connected to the end of the semiconductor cooler 622 away from the shell 10; the heat exchange component 62 also includes a plurality of first ribs 624 and second ribs 625, the first ribs 624 are connected to the side of the heat spreader 623 away from the semiconductor cooler 622 and are arranged at an angle to the heat spreader 623; the second ribs 625 are connected to the ends of each first rib 624 away from the heat spreader 623, and a plurality of heat dissipation holes 626 are provided on the second ribs 625; the second ribs 625 are connected to the structural parts.

[0093] Optionally, the heat sink 623 includes copper or aluminum.

[0094] Optionally, the first fin 624 is perpendicular to the heat sink 623 , and the first fin 624 includes copper or aluminum.

[0095] Optionally, the second fin 625 is parallel to the heat spreader 623 , and the orthographic projections of the heat spreader 623 and the shell 10 on the second fin 625 in a direction perpendicular to the heat spreader 623 are located inside the second fin 625 , and the second fin 625 includes copper or aluminum.

[0096] It can be understood that the heat dissipation holes 626 are used to connect the external environment with the gaps between adjacent first ribs 624 .

[0097] Optionally, the structural member includes a sensor housing 628, in which a receiving space with an open end is provided. The open end of the sensor housing 628 is fixed to an end of the second rib 625 close to the heat spreader 623. The sensor housing 628 and the second rib 625 enclose a space. The shell 10, the heat spreader 623 and the first rib 624 are all arranged in the space and located in the sensor housing 628.

[0098] The beneficial effects of this embodiment are as follows: the heat spreader 623 and the first fin 624 are arranged between the structural member and the shell 10, which can improve the heat conduction effect, increase the heat dissipation area, accelerate the heat dissipation of the semiconductor refrigerator 622, and improve the cooling effect of the semiconductor refrigerator 622 on the shell 10; the second fin 625 is arranged to further increase the heat dissipation area of ​​the semiconductor refrigerator 622, and the heat dissipation hole 626 can make the external airflow contact with the first fin 624 to enhance the convection heat exchange; the semiconductor refrigerator 622 has a higher cooling efficiency and is mostly used to cool the shell 10, so the heat spreader 623 is arranged at the end away from the shell 10. The heat spreader 623, the first fin 624 and the second fin 625 include copper or aluminum, which can improve the heat conduction and heat dissipation effect of the semiconductor refrigerator 622 away from the shell 10, thereby improving the cooling effect of the end of the semiconductor refrigerator 622 connected to the shell 10. The second fins 625 are parallel to the heat spreader 623, that is, the first fins 624 are arranged perpendicularly to the heat spreader 623 and the second fins 625, which can reduce the area occupied by the first fins 624 on the heat spreader 623 and the second fins 625, and thus more first fins 624 can be arranged to improve the heat dissipation effect.

[0099] In some embodiments, please refer to Figure 2 , Figure 8 and Fig. 9 The heat exchange component 62 also includes a heat spreader 623; the heat spreader 623 is connected to one end of the semiconductor cooler 622 away from the shell 10; the heat exchange component 62 also includes a plurality of heat dissipation protrusions 627, and the heat dissipation protrusions 627 are connected to one side of the heat spreader 623 away from the semiconductor cooler 622.

[0100] It can be understood that the two ends of the heat spreader 623 along the thickness direction are respectively connected to the semiconductor cooler 622 and the heat dissipation protrusion 627. Optionally, the projections of the semiconductor cooler 622 and the housing 10 on the heat spreader 623 along the thickness direction of the heat spreader 623 are located inside the heat spreader 623, and the structural member includes a sensor housing 628 with an open end, and the open end of the sensor housing 628 is fixed to an end of the heat spreader 623 close to the housing 10.

[0101] Optionally, when the thermal flow sensor 100 is used in a flow controller, the structural parts also include a housing and a base of the flow controller, and the housing and the base of the flow controller are in contact with the heat spreader 623 for heat exchange. Optionally, the sensor housing 628 or the housing of the flow controller is made of a high thermal conductivity material, and the housing is embossed to increase the heat dissipation area and improve the appearance refinement.

[0102] The beneficial effect of this embodiment is that the provision of the heat dissipation protrusion 627 can increase the heat dissipation area of ​​the heat spreader 623 , accelerate the heat dissipation of the semiconductor refrigerator 622 , and improve the cooling effect of the semiconductor refrigerator 622 on the housing 10 .

[0103] In some embodiments, please refer to Figure 2 The inner wall surface of the shell 10 is provided with a groove 11, and the temperature sensor 61 is arranged in the groove 11. The temperature sensor 61 is connected to multiple inner surfaces of the groove 11 to exchange heat with the inner surfaces of the connected grooves 11.

[0104] Optionally, the temperature sensor 61 is bonded in the groove 11 by an insulating heat-conductive adhesive.

[0105] The beneficial effect of this embodiment is that the temperature sensor 61 exchanges heat with multiple inner surfaces of the groove 11, which can improve the heat exchange efficiency between the temperature sensor 61 and the shell 10, so that the temperature sensor 61 can accurately sense the temperature of the shell 10.

[0106] In some embodiments, please refer to Figures 9 to 11 The semiconductor refrigerator 622 includes at least three insulating heat-conducting plates 6221 and at least two layers of Peltier, and the Peltier layer is sandwiched between two adjacent layers of insulating heat-conducting plates 6221.

[0107] It can be understood that the insulating heat conducting plates 6221 are parallel to each other, and a layer of Peltier is provided between any two adjacent insulating heat conducting plates 6221; the insulating heat conducting plates 6221 are used to conduct the heat of the Peltier layer and isolate two adjacent Peltier layers.

[0108] Optionally, the semiconductor refrigerator 622 also includes a cold plate 621 connected to the insulating heat conductive plate 6221 near one end of the shell 10, and the cold plate 621 is connected to the shell 10. When current flows through the semiconductor refrigerator 622, the heat generated by the current will be transferred from the cold plate 621 of the heat exchange component 62 to the heat spreader 623, generating a hot side and a cold side on the heat exchange component 62.

[0109] The beneficial effect of this embodiment is that the provision of multiple layers of Peltier can increase the power of the semiconductor cooler 622 and improve the heat exchange efficiency with the shell 10 .

[0110] In some embodiments, the thermal flow sensor 100 further includes a heat insulating member 70 , the heat exchange component 62 and the heat insulating member 70 form a heat exchange cavity, and the housing 10 is disposed in the heat exchange cavity and is attached to the heat exchange component 62 .

[0111] It can be understood that the heat exchange cavity is used to isolate the housing 10 from the environment outside the housing 10. Optionally, the heat insulating member 70 is bonded to the housing 10 by glue with a low thermal conductivity coefficient, and the heat insulating member 70 is used to install other components of the thermal flow sensor 100 located outside the housing.

[0112] The beneficial effects of this embodiment are: arranging the shell 10 in the heat exchange cavity can reduce the heat dissipation of the shell 10 to the external environment, which is beneficial to controlling the shell 10 to maintain a stable temperature; when the shell 10 is connected to other structures of the thermal flow sensor 100, or when the shell 10 is connected to other structures in the flow controller, the heat exchange between the shell 10 and other structures connected to the shell 10 can be reduced through the insulation board, and the heat exchange between the heat exchange component 62 and other structures connected to the shell 10 can be reduced, so that the temperature of the shell 10 and other structures connected to the shell 10 is more stable and more energy-saving.

[0113] In some embodiments, the flow rate of the gas is calculated using the following method:

[0114] Qm=K*(Vu 2 / Ru-Vd 2 / Rd) (1)

[0115] Among them, Qm is the flow rate, Ru is the resistance value of the upstream resistor 30, Vu is the voltage of the upstream resistor 30, Rd is the resistance value of the downstream resistor 40, Vd is the voltage of the downstream resistor 40, Ru, Vu, Rd, Vd can all be directly measured in actual work; K is the conversion coefficient, K is related to the manufacturing parameters of the sensor (such as the inner diameter of the flow channel tube 20, the resistance wire length of the heating resistor, the resistance wire value of the heating resistor, etc.), the first temperature, the second temperature and the gas properties (such as gas density, gas viscosity, gas thermal conductivity, gas specific heat capacity, etc.). In the production process, it is necessary to introduce standard gas (in this field, the standard gas is usually nitrogen) to calibrate each sensor to determine the conversion coefficient of each sensor.

[0116] In the above flow algorithm, the influence of the external ambient temperature of the flow sensor does not need to be considered, which reduces a large amount of temperature correction and approximation, making the flow calculation accuracy higher than that of the traditional thermal flow sensor 100. After the manufacturing parameters and gas properties are determined, the conversion coefficient is only related to the temperature difference between the first temperature and the second temperature. Therefore, maintaining a constant temperature difference is the key to ensuring the stability of the conversion coefficient. The smaller the change in the conversion coefficient, the more accurate the measured flow, and the higher the accuracy of the thermal flow sensor 100. The above calculation method from electrical signal to flow signal is only exemplary, and those skilled in the art can also calculate the flow using easily conceivable forms such as polynomials or exponential relationships.

[0117] Based on the above effects, the mass flow controller of the embodiment of the present application has broad application prospects in achieving high-precision and high-stability flow control; the known and potential technical and product application fields of the mass flow controller of the embodiment of the present application and its specific application methods are exemplified as follows:

[0118] Semiconductor manufacturing: Critical steps in the semiconductor manufacturing process, such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), require extremely high gas flow control accuracy. The semiconductor refrigerator 622 of the present invention controls the constant temperature of the flow sensor housing 10, allowing the device to operate at different ambient temperatures. On the one hand, it improves the measurement accuracy of the flow sensor and expands the application scenarios of the flow sensor, making it suitable for measurement accuracy in the semiconductor manufacturing process. On the other hand, it increases the reliability, repeatability and service life of the equipment.

[0119] Pharmaceutical industry production: In the field of biopharmaceuticals, especially in the process of culturing cells and producing drugs, precise gas control is crucial; the embodiments of the present application can improve the accuracy of gas flow control and ensure the accuracy and safety of drug synthesis.

[0120] Environmental monitoring equipment: In environmental protection fields such as air quality monitoring and water quality testing, it is necessary to continuously and accurately monitor and control the sampling flow; the embodiments of the present application can provide fast response and high-precision flow monitoring, thereby improving the reliability of environmental monitoring.

[0121] Laboratories and scientific research equipment: Scientific research experiments often require precise control and measurement of extremely small gas or liquid flow rates; the technical solution of the embodiments of the present application can provide fine flow control for various laboratories to ensure the accuracy and efficiency of scientific research work.

[0122] Chemical process control: In the field of chemical production and fine chemicals, the precise proportion of controlled fluids directly affects product quality. The technical solution of the embodiment of the present application provides key control parameters for fine chemical processes by providing stable and accurate flow measurement.

[0123] Aerospace and military equipment: In aerospace and military equipment, the accuracy and response time of flow control are critical to the performance of the entire system; the embodiments of the present application can provide the required high-precision flow control in these demanding applications.

[0124] Food and beverage industry: In the production process of food and beverage, the precise amount of gas and liquid added is very important for the taste and quality of the product; the embodiments of the present application can provide high-precision and high-stability flow control in these applications, making the gas and liquid addition more accurate.

[0125] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A thermal flow sensor, characterized in that: The invention comprises a shell, a flow tube, two heating resistors, a first temperature control module and a second temperature control module; the flow tube is arranged in the shell and in contact with the shell; the two heating resistors are arranged on the flow tube at intervals along the flow direction of the fluid; the heating resistor close to the upstream of the flow tube is an upstream resistor, and the heating resistor close to the downstream of the flow tube is a downstream resistor; The first temperature control module and the second temperature control module are connected to the housing, the first temperature control module is used to control the heating resistor to maintain a first temperature; the second temperature control module is used to control the housing to maintain a second temperature, and make the second temperature lower than the first temperature; The second temperature control module includes a heat exchange component and a temperature sensor connected to the heat exchange component in communication, wherein the heat exchange component is connected to the outer wall of the shell, and the heat exchange component is used to exchange heat with the shell at a basic power to control the temperature of the shell; the temperature sensor is connected to the inner wall of the shell to sense the temperature of the shell; The second temperature control module further includes a first storage unit, a first information collection unit and a first power adjustment unit, wherein the first storage unit is used to store a first preset chart; The first information acquisition unit is used to acquire a first parameter, where the first parameter is related to a voltage value of the upstream resistor, a voltage value of the downstream resistor, a resistance value of the upstream resistor, and a resistance value of the downstream resistor; The first power regulating unit is used to obtain a first compensation power according to the first preset chart and the first parameter, and the first power regulating unit is also used to control the heat exchange component to exchange heat with the shell at the sum of the basic power and the first compensation power.

2. The thermal flow sensor according to claim 1, characterized in that: The first temperature control module includes two Wheatstone bridges, the Wheatstone bridge includes a first bridge arm and a second bridge arm, the first bridge arm includes the heating resistor, the second bridge arm includes at least two temperature control resistors connected in parallel, and each of the temperature control resistors is connected in series with a switch; The temperature-controlled resistor and the heating resistor form a voltage-dividing circuit, and the resistance values ​​of the temperature-controlled resistors are different; the switch is used to switch different temperature-controlled resistors to be connected to the first bridge arm to switch the value of the first temperature.

3. The thermal flow sensor according to claim 1, characterized in that: The second temperature control module further includes a second storage unit, a second information collection unit and a second power adjustment unit, wherein the second storage unit is used to store a second preset chart; The second information acquisition unit is used to collect a second parameter, and the second parameter is related to the temperature sensed by the temperature sensor and the predicted temperature, and the predicted temperature is the temperature sensed by the temperature sensor after a response time under the current power of the heat exchange component; the second power adjustment unit is used to obtain a second compensation power according to the second preset chart and the second parameter, and the second power adjustment unit is also used to control the heat exchange component to exchange heat with the shell at the sum of the basic power and the second compensation power.

4. The thermal flow sensor according to claim 1, characterized in that: The heat exchange component includes a semiconductor refrigerator, which includes a first end and a second end. The first end has a temperature different from that of the second end. One of the second end and the first end is connected to the shell, and the other of the second end and the first end extends outside the shell and is used to connect to a structural member outside the shell and exchange heat.

5. The thermal flow sensor according to claim 4, characterized in that: The heat exchange component also includes a heat spreader; the heat spreader is connected to one end of the semiconductor refrigerator away from the shell; the heat exchange component also includes a plurality of first ribs and second ribs, the first ribs are connected to one side of the heat spreader away from the semiconductor refrigerator and are arranged at an angle to the heat spreader; the second ribs are connected to one end of each of the first ribs away from the heat spreader, and the second ribs are provided with a plurality of heat dissipation holes; the second ribs are connected to the structural member.

6. The thermal flow sensor according to claim 4, characterized in that: The heat exchange component also includes a heat spreader; the heat spreader is connected to one end of the semiconductor refrigerator away from the shell; the heat exchange component also includes a plurality of heat dissipation protrusions, and the heat dissipation protrusions are connected to one side of the heat spreader away from the semiconductor refrigerator.

7. The thermal flow sensor according to claim 4, characterized in that: The semiconductor refrigerator comprises at least three insulating heat-conducting plates and at least two layers of Peltiers, and the Peltiers are sandwiched between two adjacent layers of the insulating heat-conducting plates.

8. The thermal flow sensor according to any one of claims 4 to 7, characterized in that: The thermal flow sensor further comprises a heat insulating member, the heat exchange component and the heat insulating member enclose a heat exchange cavity, and the shell is disposed in the heat exchange cavity and is attached to the heat exchange component.

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