Thermal flow sensor and flow control system

Abstract

The utility model belongs to the technical field of flow sensors, and provides a thermal flow sensor and a flow control system.The thermal flow sensor comprises a shell, a temperature difference measuring assembly, a thermal boundary measuring assembly and a temperature control circuit board; the temperature difference measuring assembly comprises a flow channel pipe, an upstream resistor and a downstream resistor, the middle part of the flow channel pipe is arranged in the shell and is in contact with the shell, and the upstream resistor and the downstream resistor are arranged on the flow channel pipe at an interval; the thermal boundary measurement assembly comprises a temperature sensing element and a temperature reading element, the temperature sensing element is connected to the shell, and the temperature sensing element is used for collecting the temperature of the flow channel pipe through the shell; and the temperature control circuit board is used for transmitting an upstream voltage signal of the upstream resistor, a downstream voltage signal of the downstream resistor and a signal of the temperature reading element.

Description

Technical Field

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

[0002] Thermal flow sensors calculate flow by measuring the temperature difference caused by fluid flowing through a pipeline. The thermal boundary temperature of a thermal flow sensor directly affects the accuracy and stability of flow measurement. Thermal flow sensors in the prior art mostly use two voltage points (upstream voltage Vu and downstream voltage Vd) and the thermal conductivity of the measured object fluid to estimate the thermal boundary temperature of the fluid. This method requires calibration data of multiple temperature points. The thermal boundary temperature of the corresponding temperature point is estimated based on the calibration data of different temperature points. The thermal boundary temperature estimation process is complicated. Utility Model Content

[0003] The purpose of the embodiments of the present application is to provide a thermal flow sensor and a flow control system to solve the technical problem of the complex thermal boundary temperature estimation process in the thermal flow sensor in the prior art.

[0004] To achieve the above-mentioned purpose, the technical solution adopted in the present application is: to provide a thermal flow sensor, including a shell, a temperature difference measurement component, a thermal boundary measurement component, and a temperature control circuit board; the temperature difference measurement component includes a flow tube, an upstream resistor and a downstream resistor, the middle part of the flow tube is arranged in the shell and contacts the shell, and the upstream resistor and the downstream resistor are arranged at intervals on the flow tube; the thermal boundary measurement component includes a temperature sensing element and a temperature reading element, the temperature sensing element is connected to the shell, and the temperature sensing element is used to collect the temperature of the flow tube through the shell; the temperature control circuit board is electrically connected to the upstream resistor, the downstream resistor, the temperature sensing element and the temperature reading element, and the temperature control circuit board is used to transmit the upstream voltage signal of the upstream resistor, the downstream voltage signal of the downstream resistor and the signal of the temperature reading element.

[0005] The beneficial effects of this embodiment are as follows: the shell is in contact with the flow tube and a temperature sensing element connected to the shell is provided, and the temperature of the flow tube is conducted to the temperature sensing element through the shell, so that the temperature sensing element can sense the heat of the flow tube, and then directly read the thermal boundary temperature through the temperature reading element. There is no need to estimate the thermal boundary heat through a complex calculation process, and the temperature difference calculated using the upstream voltage signal and the downstream voltage signal can be directly corrected, so that the thermal flow sensor can more simply correct the temperature difference and quickly obtain flow information.

[0006] In some embodiments, the temperature sensing element includes a thermistor, the temperature reading element includes a resistor and a power supply, the resistor, the power supply and the thermistor are connected in series, and the thermistor is electrically connected to the temperature control circuit board.

[0007] The beneficial effects of this embodiment are as follows: a thermistor is provided to sense the temperature conducted by the shell; after the thermistor is connected in series with a power supply and a resistor, the voltage of the thermistor can be obtained through the voltage of the resistor and the voltage of the power supply, and then the resistance value of the thermistor and the corresponding temperature can be calculated; the temperature sensing element is set as a thermistor to be able to sensitively sense slight changes in temperature, and can reflect temperature changes in a short time, so that the thermal boundary temperature can be quickly and accurately obtained, and the flow rate can be quickly read.

[0008] In some embodiments, the temperature sensing element includes a connector, the connector is connected between the thermistor and the housing, and the connector is made of insulating thermally conductive material.

[0009] The beneficial effect of this embodiment is: an insulating and heat-conductive connector is provided to connect the temperature sensing element to the shell, which ensures that the temperature sensing element can sense the heat conducted by the shell while avoiding electrical connection between the temperature sensing element and the shell, so that the temperature sensing element can stably sense the thermal boundary temperature.

[0010] In some embodiments, the connecting member is an adhesive material to connect the thermistor to the housing.

[0011] The beneficial effect of this embodiment is that the connecting piece is set to a viscous material, so that the temperature sensing element can be directly bonded to the shell, and the connection is convenient.

[0012] In some embodiments, a thermally conductive circuit board is further included, which is disposed in the shell, the thermally conductive circuit board is bonded to the shell, and the thermally conductive circuit board is bonded to the temperature sensing element; the thermally conductive circuit board is used to connect the temperature sensing element, the upstream resistor, the downstream resistor and the temperature control circuit board to receive signals from the temperature sensing element, the upstream resistor, and the downstream resistor and output them to the temperature control circuit board.

[0013] The beneficial effects of this embodiment are as follows: a thermally conductive circuit board is arranged to fit the shell and the temperature sensing element, so that the temperature of the shell can be conducted to the temperature sensing element through the thermally conductive circuit board, and heat can be conducted to the temperature sensing element from different directions, thereby improving the heat transfer effect and making the thermal boundary temperature sensed by the temperature sensing element more accurate; at the same time, the thermally conductive circuit board can connect the temperature sensing element, the upstream resistor, the downstream resistor and the temperature control circuit board, so that the temperature control circuit board can obtain electrical signals conveniently.

[0014] In some embodiments, the thermally conductive circuit board is a ceramic circuit board or a metal-based circuit board.

[0015] The beneficial effect of this embodiment is that by setting the thermally conductive circuit board as a ceramic circuit board or a metal-based circuit board, a high thermal conductivity effect can be achieved, so that the thermal boundary temperature sensed by the temperature sensing element is more accurate.

[0016] In some embodiments, a heat conductive block for supporting the flow tube is disposed on the shell, the heat conductive block is in contact with the thermally conductive circuit board, and the heat of the flow tube can be conducted to the thermally conductive circuit board and / or the shell through the heat conductive block.

[0017] The beneficial effects of this embodiment are as follows: a heat-conducting block is provided to support the flow channel tube and the heat-conducting block is abutted against the heat-conducting circuit board, so that the temperature of the flow channel tube can be transferred to the heat-conducting circuit board through the heat-conducting block, and heat can be conducted to the heat-conducting circuit board from multiple directions, which can improve the heat conduction effect of the heat-conducting circuit board and make the thermal boundary temperature sensed by the temperature sensing element more accurate.

[0018] In some embodiments, the housing includes a groove, and the temperature sensing element is disposed in the groove.

[0019] The beneficial effects of this embodiment are as follows: the temperature sensing element is arranged in the groove of the shell, so that the temperature sensing element can sense the heat conducted by the shell from multiple directions, and at the same time can save space in the shell and reduce the volume of the thermal flow sensor.

[0020] The present application also provides a flow control system, comprising any one of the above-mentioned thermal flow sensors, and also comprising a main control circuit board and a valve, wherein the main control circuit board is connected to the temperature control circuit board, and the main control circuit board is used to receive the output signal transmitted by the temperature control circuit board and convert the output signal into a control voltage signal, and the control voltage signal is used to control the valve action; the output signal includes an upstream voltage signal, a downstream voltage signal and a signal of a temperature reading element.

[0021] The beneficial effects of this embodiment are: the flow control system includes the above-mentioned thermal flow sensor, which can simply and quickly obtain flow information, making the flow control system calculation simpler and able to quickly control the valve to adjust the flow.

[0022] In some embodiments, the main control circuit board includes a sensor analog front-end circuit, a first converter, a microcontroller, a second converter and a drive circuit; the sensor analog front-end circuit is used to receive the output signal transmitted by the temperature control circuit board, and the sensor analog front-end circuit is used to preprocess the output signal and transmit it to the first converter; the first converter is used to convert the preprocessed output signal into a digital signal and transmit the digital signal to the microcontroller; the microcontroller is used to calculate the flow rate according to the digital signal, and the microcontroller is used to generate a control signal according to the flow rate and transmit the control signal to the second converter; the second converter is used to convert the control signal into an analog control signal; the drive circuit is connected to the valve, and the drive circuit is used to receive the analog control signal and convert the analog control signal into a control voltage signal to control the valve action.

[0023] The beneficial effects of this embodiment are: setting up an analog front-end circuit, a first converter, a microcontroller, a second converter and a drive circuit can control the action state of the valve according to the signal output by the thermal flow sensor to control the size of the fluid flow flowing through the pipeline and the flow tube. 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 a thermal flow sensor provided in an embodiment of the present application;

[0026] Figure 2 Schematic diagram of the internal structure of the housing provided in the embodiment of the present application Figure 1 ;

[0027] Figure 3 Schematic diagram of the internal structure of the housing provided in the embodiment of the present application Figure 2 ;

[0028] Figure 4 Schematic diagram of the internal structure of the housing provided in the embodiment of the present application Figure 3 ;

[0029] Figure 5 A schematic diagram of a flow control system provided in an embodiment of the present application;

[0030] Figure 6 A schematic diagram of the connection between the thermal flow sensor and the main control circuit board provided in an embodiment of the present application.

[0031] Among them, the reference numerals in the figure are:

[0032] 100. Flow control system;

[0033] 10. Thermal flow sensor; 11. Housing; 111. Groove; 12. Temperature difference measurement assembly; 121. Flow channel tube; 122. Upstream resistor; 123. Downstream resistor; 13. Thermal boundary measurement assembly; 131. Temperature sensing element; 132. Temperature reading element; 1321. Resistor; 1322. Power supply; 14. Temperature control circuit board; 141. Upstream control circuit; 142. Downstream control circuit; 15. Thermally conductive circuit board; 151. Connector; 16. Thermally conductive block;

[0034] 20. Main control circuit board; 21. Sensor analog front-end circuit; 22. First converter; 23. Microcontroller; 24. Second converter; 25. Drive circuit;

[0035] 30. Valve. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The first aspect of the present application provides a thermal flow sensor 10, such as Figure 1-2 As shown, it includes a shell 11, a temperature difference measurement component 12, a thermal boundary measurement component 13, and a temperature control circuit board 14; the temperature difference measurement component 12 includes a flow tube 121, an upstream resistor 122 and a downstream resistor 123, the middle part of the flow tube 121 is arranged in the shell 11 and contacts the shell 11, and the upstream resistor 122 and the downstream resistor 123 are arranged at intervals on the flow tube 121; the thermal boundary measurement component 13 includes a temperature sensing element 131 and a temperature reading element 132, the temperature sensing element 131 is connected to the shell 11, and the temperature sensing element 131 is used to collect the temperature of the flow tube 121 through the shell 11; the temperature control circuit board 14 is electrically connected to the upstream resistor 122, the downstream resistor 123, the temperature sensing element 131 and the temperature reading element 132, and the temperature control circuit board 14 is used to transmit the upstream voltage signal Vu of the upstream resistor 122, the downstream voltage signal Vd of the downstream resistor 123 and the signal of the temperature reading element 132.

[0041] The shell 11 is a hollow structure and is used to isolate the measurement environment from the external environment, thereby reducing the influence of the external environment temperature on the flow channel tube 121 , the upstream resistor 122 , the downstream resistor 123 and the temperature sensing element 131 .

[0042] The shell 11 is made of a heat-conducting material, such as aluminum, graphite or heat-conducting ceramics; the shell 11 is in contact with the flow tube 121 and can conduct the thermal boundary temperature around the flow tube 121, which is convenient for measuring the thermal boundary temperature. The thermal boundary temperature is the temperature of the surrounding environment of a section of the flow tube 121 between the upstream resistor 122 and the downstream resistor 123.

[0043] The flow rate of the fluid is different, and the temperature change of the fluid after passing through the flow channel tube 121 is also different; the temperature difference measurement component 12 is used to measure the temperature change of the fluid after passing through a section of the flow channel tube 121, and the flow rate of the fluid can be calculated based on the temperature change of the fluid. At the same time, the temperature of the fluid will also be affected by the external environment. The thermal boundary measurement component 13 is used to measure the thermal boundary temperature (the temperature of the environment around the flow channel tube 121), and the measured fluid flow rate is corrected by the thermal boundary temperature.

[0044] The flow tube 121 is used to connect to the device under test. The fluid in the device under test flows into the flow tube 121. The flow tube 121 is conveniently connected to the temperature difference measurement component 12 to facilitate the measurement of the fluid. Optionally, the flow tube 121 is in direct contact with the shell 11 for heat conduction, and the flow tube 121 is connected to the shell 11 by fasteners.

[0045] The upstream resistor 122 and the downstream resistor 123 are located in the housing 11 . The upstream resistor 122 and the downstream resistor 123 are arranged in the middle of the flow tube 121 , and are used to heat the fluid in the flow tube 121 and detect the heat change of the fluid.

[0046] Optionally, the upstream resistor 122 and the downstream resistor 123 are heating resistor wires, and the upstream resistor 122 and the downstream resistor 123 are coil-like structures sleeved on the flow tube 121; optionally, the upstream resistor 122 and the downstream resistor 123 can also be thermistors, and the upstream resistor 122 and the downstream resistor 123 are bonded to the flow tube 121 with high thermal conductivity glue.

[0047] The temperature sensing element 131 is connected to the housing 11 and is used to measure the thermal boundary temperature conducted by the housing 11 .

[0048] The temperature reading element 132 is used to convert the thermal boundary temperature signal measured by the temperature sensing element 131, and the temperature signal of the temperature sensing element 131 can be conveniently read through the temperature reading element 132; for example, the temperature sensing element 131 uses a thermocouple, and the temperature reading element 132 uses an electrical meter. The thermocouple converts the temperature signal into an electromotive force signal, and then the electromotive force signal is converted into temperature through the electrical meter.

[0049] Optionally, the temperature control circuit board 14 includes an upstream control circuit 141 and a downstream control circuit 142, the upstream control circuit 141 is electrically connected to the upstream resistor 122, and the downstream control circuit 142 is electrically connected to the downstream resistor 123. When the fluid flows through the flow channel tube 121, the upstream resistor 122 and the downstream resistor 123 measure the temperature, and convert the temperature into an upstream voltage signal Vu and a downstream voltage signal Vd through the upstream control circuit 141 and the downstream control circuit 142 respectively; the temperature control circuit board 14 reads the upstream voltage signal Vu, the downstream voltage signal Vd and the signal of the temperature reading element 132, thereby facilitating the calculation of the temperature change of the fluid between the upstream resistor 122 and the downstream resistor 123 and the thermal boundary temperature, and then calculating the flow rate of the fluid.

[0050] Optionally, the temperature control circuit board 14 is arranged outside the shell 11, which can reduce the space occupied by the shell 11 and reduce the volume of the shell 11; optionally, the temperature control circuit board 14 can also be arranged inside the shell 11 to reduce external interference.

[0051] Optionally, the thermal flow sensor 10 includes multiple wires, which connect the temperature sensing element 131, the upstream resistor 122, the downstream resistor 123 and the temperature control circuit board 14, and output the signals of the temperature sensing element 131, the upstream resistor 122, and the downstream resistor 123 to the temperature control circuit board 14; this embodiment does not need to set up a thermal conductive circuit board 15, and the cost is relatively low.

[0052] The beneficial effects of this embodiment are as follows: the housing 11 is in contact with the flow tube 121 and a temperature sensing element 131 connected to the housing 11 is provided, and the temperature of the flow tube 121 is conducted to the temperature sensing element 131 through the housing 11, so that the temperature sensing element 131 can sense the heat of the flow tube 121, and then directly read the thermal boundary temperature through the temperature reading element 132; the circuits of the temperature difference measurement component 12 and the thermal boundary measurement component 13 are separated, and the measured thermal boundary temperature is not affected by the temperature difference measurement component 12, and the measurement is more accurate; at the same time, the temperature sensing element 131 and the upstream resistor 122 and the downstream resistor 123 can all be provided in the housing 11, and the overall structure is more centralized; the temperature sensing element 131 and the thermal boundary heat do not need to be estimated through a complex calculation process, and the read thermal boundary temperature is not affected by the fluid flow rate, and the flow rate calculated using the upstream voltage signal Vu and the downstream voltage signal Vd can be directly corrected, so that the thermal flow sensor 10 can more simply correct the flow rate and quickly obtain accurate flow information; even when the fluid flow rate changes rapidly, stable and accurate temperature readings can be provided.

[0053] In some embodiments, Figure 6 As shown, the temperature sensing element 131 includes a thermistor (NTC), the temperature reading element 132 includes a resistor 1321 and a power source 1322, the resistor 1321, the power source 1322 and the thermistor are connected in series, and the thermistor is electrically connected to the temperature control circuit board 14.

[0054] Optionally, when the housing 11 is made of insulating materials such as thermally conductive ceramics, insulating fasteners may be used to fix the thermistor to the housing 11 .

[0055] Resistor 1321 and power supply 1322 are connected in series with the thermistor, the voltage of power supply 1322 is fixed, the voltage of the thermistor can be calculated based on the voltage of power supply 1322 and the voltage of resistor 1321, the voltage ratio and resistance ratio of the thermistor to the voltage of resistor 1321 are equal, and the resistance of the thermistor can be calculated based on the voltage and resistance of resistor 1321 and the voltage of the thermistor. The resistance of the thermistor changes with the change of temperature, and the real-time thermal boundary temperature value can be obtained from the preset inherent impedance-temperature characteristics of the thermistor.

[0056] Optionally, the signal of the temperature reading element 132 is a voltage signal of the resistor 1321 .

[0057] Optionally, the resistor 1321 is a precision resistor with a small resistance error, so that the calculated thermal boundary temperature is more accurate; the thermistor is grounded through the precision resistor.

[0058] The beneficial effects of this embodiment are as follows: the temperature sensing element 131 is set as a thermistor which can sensitively sense slight changes in the temperature conducted by the shell 11, can quickly reach a thermal equilibrium state, and reflect temperature changes in a short time, greatly shortening the waiting time; at the same time, the production of thermistors is more stable, and the error between different products is small, so that the thermal boundary temperature can be quickly and accurately obtained, and the flow rate can be quickly read.

[0059] In other embodiments, the temperature sensing element 131 is a thermocouple or an infrared sensor, and the thermal boundary temperature is measured by the thermocouple and the infrared sensor, without providing the resistor 1321 for voltage division calculation.

[0060] In some embodiments, the temperature sensing element 131 includes a connector connected between the thermistor and the housing 11 , and the connector includes an insulating thermally conductive material.

[0061] The connector is used to fix the thermistor on the housing 11 and isolate the thermistor from the housing 11 to provide an insulating environment for the thermistor. Especially when the housing 11 is made of conductive materials such as aluminum shell, the connector can prevent conduction between the aluminum shell and the thermistor and prevent damage to the thermistor.

[0062] Optionally, the connecting piece is an insulating heat-conducting material such as a thermally conductive silicone sheet; an insulating fastener is used to fix the thermistor to the thermally conductive silicone sheet, and the thermally conductive silicone sheet is fixed to the housing 11.

[0063] The beneficial effects of this embodiment are as follows: an insulating and heat-conductive connector is provided to connect the temperature sensing element 131 to the shell 11, which ensures that the temperature sensing element 131 can sense the heat conducted by the shell 11 while avoiding electrical connection between the temperature sensing element 131 and the shell 11, so that the temperature sensing element 131 can stably sense the thermal boundary temperature.

[0064] In some embodiments, the connecting member is an adhesive material to connect the thermistor to the housing 11 .

[0065] Optionally, the connector is made of materials such as high thermal conductivity glue or thermal grease, which facilitates bonding and fixing the thermistor to the housing 11 while providing insulation and heat conduction.

[0066] The beneficial effect of this embodiment is that the connecting piece is set to a viscous material, so that the thermistor can be directly bonded to the housing 11, and the installation is more convenient.

[0067] In some embodiments, Figure 2-3As shown, the thermal flow sensor 10 also includes a thermally conductive circuit board 15, which is disposed in the housing 11, the thermally conductive circuit board 15 is bonded to the housing 11, and the thermally conductive circuit board 15 is bonded to the temperature sensing element 131; the thermally conductive circuit board 15 is used to connect the temperature sensing element 131, the upstream resistor 122, the downstream resistor 123 and the temperature control circuit board 14, so as to receive signals from the temperature sensing element 131, the upstream resistor 122, and the downstream resistor 123 and output them to the temperature control circuit board 14.

[0068] The heat-conducting circuit board 15 is used to electrically connect the temperature control circuit board 14 and the temperature sensing element 131, the upstream resistor 122, and the downstream resistor 123 in the housing 11, and can conduct heat, and has both heat and electricity conduction functions. The heat-conducting circuit board 15 can be set as a special-shaped structure that can improve heat exchange efficiency.

[0069] Optionally, a temperature sensing element 131 is sandwiched between the thermally conductive circuit board 15 and the housing 11 ; and a thermally conductive material is disposed in the gap between the thermally conductive circuit board 15 and the housing 11 for heat transfer.

[0070] The beneficial effects of this embodiment are as follows: the thermally conductive circuit board 15 is arranged to fit the shell 11 and the temperature sensing element 131, so that the temperature of the shell 11 can be conducted to the temperature sensing element 131 through the thermally conductive circuit board 15, and the thermal boundary temperature can also be conducted to the temperature sensing element 131 through the shell 11, and the heat can be conducted to the temperature sensing element 131 from different directions, thereby improving the heat transfer effect and making the thermal boundary temperature sensed by the temperature sensing element 131 more accurate; at the same time, the thermally conductive circuit board 15 can connect the temperature sensing element 131, the upstream resistor 122, the downstream resistor 123 and the temperature control circuit board 14, so that the temperature control circuit board 14 can obtain electrical signals conveniently.

[0071] In some embodiments, the thermally conductive circuit board 15 includes a connector 151, and the connector 151 includes multiple conductors and multiple conductive columns. The conductor is arranged in the thermally conductive circuit board 15, and the conductor can be set as copper foil. The temperature control circuit board 14 is arranged outside the shell 11, and the shell 11 is provided with holes for the conductors to pass through; one ends of the multiple conductors are respectively electrically connected to the upstream resistor 122, the downstream resistor 123 and the temperature sensing element 131, and the other ends of the multiple conductors are respectively connected to the multiple conductive columns, each conductor is connected to a conductive column, and the conductive column passes through the holes on the shell 11 and is electrically connected to the temperature control circuit board 14 outside the shell 11.

[0072] A connector 151 is provided on the thermally conductive circuit board 15 to make the circuit between the temperature sensing element 131, the upstream resistor 122, the downstream resistor 123 and the temperature control circuit board 14 more stable; and the temperature control circuit board 14 is provided outside the shell 11 to reduce the influence of the temperature of the temperature circuit board on the temperature inside the shell 11, and at the same time to reduce the volume of the shell 11.

[0073] In some embodiments, the thermally conductive circuit board 15 is a ceramic circuit board or a metal-based circuit board or a circuit board using other high thermal conductive substrates.

[0074] A ceramic circuit board is a circuit board that uses a thermally conductive ceramic substrate. The ceramic circuit board includes ceramic substrates such as aluminum oxide and aluminum nitride. The thermal conductivity of the ceramic circuit board is above 20W / (m·K). For example, it can be different values ​​such as 25W / (m·K), 30W / (m·K) or 50W / (m·K).

[0075] Metal-based circuit boards are circuit boards that use metal substrates. Different metal substrates have different thermal conductivities. For example, the thermal conductivity of an aluminum substrate is about 200-250W / (m·K), and the thermal conductivity of a copper substrate is about 350-400W / (m·K).

[0076] The beneficial effects of this embodiment are: the thermally conductive circuit board 15 is set to a ceramic circuit board or a metal-based circuit board, which can achieve a high thermal conductivity effect compared with the traditional substrate, so that the temperature change can be quickly transmitted from the flow channel tube 121 area to the temperature sensing element 131, so that the thermal boundary temperature sensed by the temperature sensing element 131 is more accurate, which can improve the temperature response speed and measurement accuracy of the thermal flow sensor 10.

[0077] In some embodiments, Figure 2 As shown, a heat conducting block 16 for supporting the flow tube 121 is provided on the shell 11 . The heat conducting block 16 abuts against the heat conducting circuit board 15 . The heat of the flow tube 121 can be transferred to the heat conducting circuit board 15 and / or the shell 11 through the heat conducting block 16 .

[0078] Optionally, two heat-conducting blocks 16 are provided, and the upstream resistor 122 and the downstream resistor 123 are arranged between the two heat-conducting blocks 16; a mounting groove is opened on the heat-conducting block 16, and the flow channel tube 121 is arranged in the mounting groove, so that the position of the flow channel tube 121 is more stable.

[0079] The beneficial effects of this embodiment are as follows: a heat-conducting block 16 is provided to support the flow tube 121 and the heat-conducting block 16 is abutted against the heat-conducting circuit board 15, so that the temperature of the flow tube 121 can be transferred to the heat-conducting circuit board 15 through the heat-conducting block 16, and heat can be conducted to the heat-conducting circuit board 15 from multiple directions, which can improve the heat conduction effect of the heat-conducting circuit board 15 and make the thermal boundary temperature sensed by the temperature sensing element 131 more accurate.

[0080] In some embodiments, Figure 4 As shown, the housing 11 includes a groove 111 , and the temperature sensing element 131 is disposed in the groove 111 .

[0081] Optionally, the groove 111 is provided on a surface of the housing 11 opposite to the heat-conducting circuit board 15 .

[0082] Optionally, the groove 111 may be configured as a contoured structure corresponding to the temperature sensing element 131 , so that the temperature sensing element 131 is embedded in the groove 111 .

[0083] The beneficial effects of this embodiment are as follows: the temperature sensing element 131 is disposed in the groove 111 of the shell 11, so that the temperature sensing element 131 can sense the heat conducted by the shell 11 from multiple directions, while saving space in the shell 11 and reducing the volume of the thermal flow sensor 10; after the temperature sensing element 131 is placed in the groove 111, the thermally conductive circuit board 15 can also better fit with the shell 11.

[0084] The present application also provides a flow control system 100, such as Figure 5 As shown, the thermal flow sensor 10 includes any one of the above-mentioned first aspects, and also includes a main control circuit board 20 and a valve 30. The main control circuit board 20 is connected to the temperature control circuit board 14. The main control circuit board 20 is used to receive the output signal transmitted by the temperature control circuit board 14 and convert the output signal into a control voltage signal. The control voltage signal is used to control the action of the valve 30; the output signal includes an upstream voltage signal Vu, a downstream voltage signal Vd and a signal of the temperature reading element 132.

[0085] The main control circuit board 20 calculates the output signal, calculates the flow rate according to the upstream voltage signal Vu and the downstream voltage signal Vd, calculates the thermal boundary temperature according to the signal of the temperature reading element 132 and corrects the flow rate according to the thermal boundary temperature, calculates the flow rate of the fluid in the flow tube 121 according to the corrected temperature difference, and calculates the control voltage signal of the valve 30 according to the flow rate of the fluid in the flow tube 121.

[0086] Optionally, the temperature sensing element 131 is powered by a voltage reference source on the main control circuit board 20, and the voltage reference source provides a low-noise, high-precision power supply 1322 to improve detection accuracy.

[0087] After receiving the control voltage signal from the main control circuit board 20 , the valve 30 is adjusted to a corresponding opening to control the flow of the fluid in the pipeline connected to the valve 30 and the flow channel pipe 121 .

[0088] The beneficial effects of this embodiment are: the flow control system 100 includes the above-mentioned thermal flow sensor 10, which can simply and quickly obtain flow information, making the flow calculation of the flow control system 100 simpler, and then being able to quickly control the valve 30 to adjust the flow.

[0089] In some embodiments, Figure 5-6As shown, the main control circuit board 20 includes a sensor analog front-end circuit 21, a first converter 22, a microcontroller 23 (Microcontroller Unit, MCU), a second converter 24 and a drive circuit 25; the sensor analog front-end circuit 21 is used to receive the output signal transmitted by the temperature control circuit board 14, and the sensor analog front-end circuit 21 is used to pre-process the output signal and transmit it to the first converter 22; the first converter 22 is used to convert the pre-processed output signal into a digital signal and transmit the digital signal to the microcontroller 23; the microcontroller 23 is used to calculate the flow rate according to the digital signal, and the microcontroller 23 is used to generate a control signal according to the flow rate and transmit the control signal to the second converter 24; the second converter 24 is used to convert the control signal into an analog control signal; the drive circuit 25 is connected to the valve 30, and the drive circuit 25 is used to receive the analog control signal and convert the analog control signal into a control voltage signal to control the action of the valve 30.

[0090] The sensor analog front-end circuit 21 receives the output signal transmitted by the thermal flow sensor 10. The output signal includes analog signals such as the upstream voltage signal Vu, the downstream voltage signal Vd and the signal of the temperature reading element 132 (such as the voltage signal of the resistor 1321). The sensor analog front-end circuit 21 includes a preprocessing circuit, which performs preprocessing operations such as filtering, amplifying, calculating and multiplexing the output signal.

[0091] Optionally, the first converter 22 is an analog to digital converter (ADC), and the first converter 22 converts the preprocessed output signal into a digital signal for processing by the microcontroller 23 .

[0092] The microcontroller 23 is the calculation and control center of the flow control system 100. The microcontroller 23 receives the digital signal from the first converter 22, calculates the actual flow rate and generates a corresponding digital control signal based on the values ​​of the upstream voltage signal Vu, the downstream voltage signal Vd and the temperature value of the temperature sensor element 131 detected in real time, and then transmits the digital control signal to the second converter 24.

[0093] Optionally, the temperature sensing element 131 is a thermistor, and the temperature reading element 132 includes a precision resistor and a voltage reference source connected in series with the thermistor; the microcontroller 23 can calculate the real-time impedance of the thermistor through the voltage divider value between the thermistor and the precision resistor and the voltage value of the known voltage reference source, and the real-time thermal boundary temperature value can be obtained from the preset thermistor inherent impedance-temperature characteristic. The microcontroller 23 simultaneously calculates the flow value before correction through the upstream voltage signal Vu and the downstream voltage signal Vd, and then calculates the corrected real flow value of the fluid based on the thermal boundary temperature value and the preset thermal boundary temperature of different fluids on the flow influence curve. The microcontroller 23 generates a digital control signal of the valve 30 through a control algorithm based on the real flow value and the target flow value.

[0094] Optionally, the second converter 24 is a digital to analog converter (DAC), which converts the digital control signal generated by the microcontroller 23 into an analog control signal, and the analog control signal is used to adjust the input control signal of the piezoelectric drive circuit to achieve precise control of the fluid flow.

[0095] The drive circuit 25 is connected to the second converter 24 and the valve 30. The drive circuit 25 is used to convert the analog control signal into different voltage values ​​to obtain a control voltage signal. The drive circuit 25 controls the physical movement of the valve 30 through the control voltage signal to adjust the flow rate of the fluid flowing through the valve 30 so that the measured actual flow value is the same as the target flow value.

[0096] Optionally, the driving circuit 25 is a piezoelectric driving circuit, the valve 30 is a piezoelectric ceramic valve, the piezoelectric ceramic valve includes a piezoelectric actuator, the piezoelectric driving circuit controls the action of the piezoelectric actuator by controlling the voltage signal, the piezoelectric actuator controls the opening of the piezoelectric ceramic valve, and adjusts the flow of the fluid through the piezoelectric ceramic valve. The piezoelectric ceramic valve has a fast response speed and can quickly adjust the fluid flow.

[0097] The beneficial effects of this embodiment are as follows: the analog front-end circuit, the first converter 22, the microcontroller 23, the second converter 24 and the drive circuit 25 are arranged to control the action state of the valve 30 according to the signal output by the thermal flow sensor 10, so as to control the size of the fluid flow through the pipeline and the flow tube 121, and to perform real-time automatic control of the fluid flow.

[0098] Based on the above effects, any 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 embodiments of the present application and their specific application methods are exemplified as follows:

[0099] Semiconductor manufacturing: Key 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 embodiments of the present application can provide more accurate flow data to ensure the consistency of the semiconductor manufacturing process and the quality of the product.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] The above are only preferred embodiments of the present application and are 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: It includes a housing, a temperature difference measurement component, a thermal boundary measurement component, and a temperature control circuit board; The temperature difference measurement assembly comprises a flow channel tube, an upstream resistor and a downstream resistor, the middle portion of the flow channel tube is arranged in the shell and in contact with the shell, and the upstream resistor and the downstream resistor are arranged on the flow channel tube at intervals; The thermal boundary measurement assembly includes a temperature sensing element and a temperature reading element, wherein the temperature sensing element is connected to the housing and is used to collect the temperature of the flow channel tube through the housing; The temperature control circuit board is electrically connected to the upstream resistor, the downstream resistor, the temperature sensing element and the temperature reading element, and is used to transmit the upstream voltage signal of the upstream resistor, the downstream voltage signal of the downstream resistor and the signal of the temperature reading element.

2. The thermal flow sensor according to claim 1, characterized in that: The temperature sensing element comprises a thermistor, the temperature reading element comprises a resistor and a power source, the resistor, the power source and the thermistor are connected in series, and the thermistor is electrically connected to the temperature control circuit board.

3. The thermal flow sensor according to claim 2, characterized in that: The temperature sensing element comprises a connecting piece, the connecting piece is connected between the thermistor and the shell, and the connecting piece is made of insulating heat-conducting material.

4. The thermal flow sensor according to claim 3, characterized in that: The connecting member is an adhesive material to connect the thermistor to the housing.

5. The thermal flow sensor according to claim 1, characterized in that: It also includes a heat-conducting circuit board, which is arranged in the housing, the heat-conducting circuit board is attached to the housing, and the heat-conducting circuit board is attached to the temperature sensing element; The thermally conductive circuit board is used to connect the temperature sensing element, the upstream resistor, the downstream resistor and the temperature control circuit board to receive signals from the temperature sensing element, the upstream resistor and the downstream resistor and output them to the temperature control circuit board.

6. The thermal flow sensor according to claim 5, characterized in that: The thermally conductive circuit board is a ceramic circuit board or a metal-based circuit board.

7. The thermal flow sensor according to claim 5, characterized in that: The shell is provided with a heat-conducting block for supporting the flow tube, the heat-conducting block is in contact with the heat-conducting circuit board, and the heat of the flow tube can be conducted to the heat-conducting circuit board and / or the shell through the heat-conducting block.

8. The thermal flow sensor according to any one of claims 1 to 7, characterized in that: The housing includes a groove, and the temperature sensing element is arranged in the groove.

9. A flow control system, characterized in that: The thermal flow sensor comprises the thermal flow sensor as described in any one of claims 1 to 8, and further comprises a main control circuit board and a valve, wherein the main control circuit board is connected to a temperature control circuit board, the main control circuit board is used to receive an output signal transmitted by the temperature control circuit board and convert the output signal into a control voltage signal, and the control voltage signal is used to control the action of the valve; the output signal comprises an upstream voltage signal, a downstream voltage signal and a signal of a temperature reading element.

10. The flow control system according to claim 9, characterized in that: The main control circuit board includes a sensor analog front-end circuit, a first converter, a microcontroller, a second converter and a driving circuit; The sensor analog front-end circuit is used to receive the output signal transmitted by the temperature control circuit board, and the sensor analog front-end circuit is used to pre-process the output signal and transmit it to the first converter; The first converter is used to convert the preprocessed output signal into a digital signal and transmit the digital signal to the microcontroller; The microcontroller is used to calculate the flow rate according to the digital signal, and the microcontroller is used to generate a control signal according to the flow rate and transmit the control signal to the second converter; The second converter is used to convert the control signal into an analog control signal; The driving circuit is connected to the valve, and is used for receiving the analog control signal and converting the analog control signal into a control voltage signal to control the valve action.

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