Gas flow detection device

Abstract

The utility model discloses a gas flow detection device, which comprises an annular shell, a PCB (Printed Circuit Board), a thermistor type temperature sensor, two platinum resistance type temperature sensors and a constant-current power supply, the PCB is fixed in the annular shell, the constant-current power supply, the thermistor type temperature sensor and the two platinum resistance type temperature sensors are all installed on the PCB, and the two platinum resistance type temperature sensors are located on the two sides of the PCB; the constant-current power supply is respectively and electrically connected with the thermistor type temperature sensor and the two platinum resistance type temperature sensors, and the thermistor type temperature sensor and the two platinum resistance type temperature sensors are respectively and electrically connected with the control circuit on the PCB. The device is simple in overall structure, small in size, more accurate in measurement and suitable for being used in various working conditions limited by the size.

Description

Technical Field

[0001] The utility model relates to the technical field of gas flow detection equipment, in particular to a gas flow detection device. Background Art

[0002] Gas mass flow is an important and complex design problem in the field of engineering. In many industrial and scientific applications, accurate measurement of gas mass flow is crucial. Most traditional gas flow sensors detect flow through gas pipes, which are bulky and only suitable for scenarios where gas pipes are connected. Utility Model Content

[0003] In order to solve the technical problems existing in the background technology, the utility model proposes a gas flow detection device.

[0004] The utility model provides a gas flow detection device, comprising: an annular housing, a PCB board, a thermistor temperature sensor, two platinum resistance temperature sensors and a constant current power supply;

[0005] The PCB board is fixed inside the annular housing, and the constant current power supply, the thermistor temperature sensor and two platinum resistance temperature sensors are all installed on the PCB board, and the two platinum resistance temperature sensors are located on both sides of the PCB board;

[0006] The constant current power supply is electrically connected to the thermistor temperature sensor and the two platinum resistance temperature sensors respectively, and the thermistor temperature sensor and the two platinum resistance temperature sensors are electrically connected to the control circuit on the PCB board respectively.

[0007] Preferably, the PCB board is located on the axial section of the annular housing.

[0008] Preferably, the control circuit includes an MCU, a filter and rectifier unit and a voltage detection unit, the thermistor temperature sensor and two platinum resistance temperature sensors are electrically connected to the voltage detection unit respectively, the voltage detection unit is electrically connected to the filter and rectifier unit, and the filter and rectifier unit is electrically connected to the MCU.

[0009] Preferably, the control circuit further comprises a wireless transmission unit, which is electrically connected to the MCU and is used to transmit the calculated gas flow to a remote server or a mobile client.

[0010] Preferably, symmetrical receiving grooves for receiving the PCB board on both sides are provided on the inner wall of the annular shell, and notches for the PCB board on both sides to enter and exit the receiving groove are provided at one end of the annular shell corresponding to the receiving groove; at least one countersunk hole connected to the receiving groove is provided on the annular shell corresponding to each receiving groove, and bolts for fixing the annular shell and the PCB board are passed through the countersunk hole.

[0011] Preferably, the front end of the bolt extends out of the countersunk hole and is threadedly connected to the PCB board.

[0012] Preferably, through holes for the bolts to pass through are provided at locations corresponding to the PCB board and the bolts, and the front end of the bolts passes through the countersunk hole and the through hole in sequence and is threadedly connected to the annular housing.

[0013] In the utility model, the proposed gas flow detection device, before calculating the gas flow according to the resistance change caused by the temperature change of thermistor temperature sensor and platinum resistance temperature sensor due to the gas flow, first uses two platinum resistance temperature sensors to increase the judgment of the environmental state, and through repeated tests, it can eliminate the flow detection error caused by foreign matter interfering with the gas flow rate or the flow calculation error caused by the measurement error of a single sensor, so as to achieve more reliable flow detection. Moreover, the overall structure is simple, the volume is small, there are no moving parts and pressure sensing parts, the measurement accuracy is not affected by vibration, and the pressure and temperature of the environment have no effect on the measurement results, and it can be used in various working conditions with volume restrictions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic structural diagram of a gas flow detection device in an embodiment of the present invention.

[0015] Figure 2 This is a schematic structural diagram of a gas flow detection device in another embodiment of the present utility model.

[0016] Figure 3 This is a schematic structural diagram of a gas flow detection device in another embodiment of the present invention. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] Reference Figure 1 The utility model proposes a gas flow detection device, comprising: an annular housing 1, a PCB board 2, a thermistor temperature sensor 4, two platinum resistance temperature sensors 3 and a constant current power supply 5;

[0019] The PCB board 2 is fixed inside the annular housing 1, the constant current power supply 5, the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3 are all installed on the PCB board 2, and the two platinum resistance temperature sensors 3 are located on both sides of the PCB board 2, the constant current power supply 5 is electrically connected to the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3 respectively, and the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3 are electrically connected to the control circuit on the PCB board 2 respectively.

[0020] In the specific implementation, a stable air duct is formed inside the annular shell 1 to avoid flow rate fluctuations caused by interference from various foreign objects in the installation environment; the thermistor temperature sensor 4 and two platinum resistance temperature sensors 3 on the PCB board 2 inside the annular shell 1 detect the change in their own resistance caused by the temperature change in the gas flow channel, and the control circuit calculates the gas flow rate through the resistance change of the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3. Among them, the ambient temperature detected by the thermistor temperature sensor 4 is used as a reference temperature benchmark, and one platinum resistance temperature sensor 3 detects the ambient temperature while being powered on and heated. When the gas flow takes away the heat, the temperature of the platinum resistance sensor will decrease; the other platinum resistance temperature sensor 3 detects the ambient temperature while being powered on and heated, which can be used as a detection calibration.

[0021] Before calculating the gas flow rate according to the resistance change caused by the temperature change of thermistor temperature sensor 4 and platinum resistance temperature sensor 3 due to the gas flow, the utility model first uses two platinum resistance temperature sensors 3 to increase the judgment of the environmental state, and can eliminate the flow detection error caused by foreign matter interfering with the gas flow rate or the flow calculation error caused by the measurement error of a single sensor through repeated tests, so as to achieve more reliable flow detection. Moreover, the overall structure is simple, the volume is small, there are no moving parts and pressure sensing parts, the measurement accuracy is not affected by vibration, and the pressure and temperature of the environment have no effect on the measurement results, and it can be applied to various working conditions limited by volume.

[0022] Among them, the constant current power supply 5 serves as the power supply of the three temperature sensors. The difference between the self-heating of the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3 and the temperature drop when powered on is solidified through the adjusted current, thereby avoiding external changes that cause changes in the heat generation of the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3 themselves, which is beneficial to improving accuracy.

[0023] In this embodiment, the PCB board 2 is located on the axial section of the annular housing 1 to ensure that the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3 are located in the middle of the annular housing 1, which is beneficial to improving the measurement accuracy.

[0024] Since the PCB board 2 is directly exposed to the airflow, in order to protect the control circuit on the PCB board 2, in this embodiment, the surface of the PCB board 2 is treated with anti-mildew, anti-moisture and anti-salt spray protection.

[0025] In this embodiment, the control circuit includes an MCU, a filter and rectifier unit, and a voltage detection unit. The thermistor temperature sensor 4 and two platinum resistance temperature sensors 3 are electrically connected to the voltage detection unit respectively, the voltage detection unit is electrically connected to the filter and rectifier unit, and the filter and rectifier unit is electrically connected to the MCU.

[0026] During specific use, the voltage detection unit is used to detect the voltage changes caused by the resistance changes of the two resistive sensors due to the temperature changes caused by the gas flow; the filtering and rectifying unit is used to filter and rectify the voltage changes to shield some gas flow rate fluctuations caused by the passage of foreign objects, and transmit the rectified voltage changes to the MCU; the MCU is used to convert the rectified voltage changes into precise resistance changes through a table lookup method, and calculate the resistance changes per unit time as real-time gas flow rate in conjunction with the preset algorithm, and then based on the fixed inlet and outlet areas, the gas flow in the area can be accurately measured.

[0027] Among them, the MCU first calculates the corresponding temperature through the thermistor temperature sensor 4 and the two platinum resistance temperature sensors 3, and calculates the temperature difference between the two platinum resistance temperature sensors 3 and the thermistor temperature sensor 4 respectively; when one of the temperature differences exceeds the preset range, the measurement data of the platinum resistance temperature sensor 3 exceeding the preset range is removed, and the real-time gas flow rate is calculated based on the measurement data of the platinum resistance temperature sensor 3 and the thermistor temperature sensor 4 that do not exceed the preset range, thereby calculating the real-time gas flow rate; when both temperature differences do not exceed the preset range, the real-time gas flow rate is calculated based on the average value of the measurement data of the two platinum resistance temperature sensors 3 and the measurement data of the thermistor temperature sensor 4, thereby calculating the real-time gas flow rate; when both temperature differences exceed the preset range, the measurement data of the platinum resistance temperature sensor 3 exceeding the preset range is removed.

[0028] The overall digital circuit measurement of this embodiment can accurately measure the gas flow rate and is easy to maintain.

[0029] The calculation formula for gas flow is:

[0030]

[0031] Where: V is the gas flow rate (kg / m 3 ), S is the cross-sectional area (m 3 ), ρ z is the medium density under working volume (kg / m 3), K is the equilibrium coefficient, Q is the amount of heating (related to specific heat and structure) (J), T1 is the temperature measured by the thermistor temperature sensor 4 (°C), and T2 is the temperature measured by the platinum resistance temperature sensor 3 (°C).

[0032] in,

[0033] Where: z is the medium density under working volume (kg / m 3 ), ρ n The medium density under standard conditions (101.325Kpa, 20℃) (kg / m 3 ), P is the operating pressure (Pa), T is the operating temperature (℃).

[0034] Specifically, the filtering and rectifying unit is a Gaussian filter.

[0035] In this embodiment, the control circuit also includes a wireless transmission unit, which is electrically connected to the MCU. The wireless transmission unit is used to transmit the calculated gas flow to a remote server or mobile client for easy viewing.

[0036] In one specific embodiment, the thermistor temperature sensor 4 is an epoxy resin encapsulated NTC thermistor temperature sensor 4 .

[0037] In this embodiment, symmetrical receiving grooves for receiving the PCB board 2 on both sides are provided on the inner wall of the annular shell 1, and notches for the PCB board 2 on both sides to enter and exit the receiving groove are provided at one end of the annular shell 1 corresponding to the receiving groove; at least one countersunk hole connected to the receiving groove is provided on the annular shell 1 corresponding to each receiving groove, and a bolt 6 for fixing the annular shell 1 and the PCB board 2 is passed through the countersunk hole.

[0038] like Figure 3 As shown, in one specific embodiment, the front end of the bolt 6 extends out of the countersunk hole and is threadedly connected to the PCB board 2.

[0039] like Figure 2 As shown, in another specific embodiment, a through hole for the bolt 6 to pass through is opened at the corresponding position of the PCB board 2 and the bolt 6, and the front end of the bolt 6 passes through the countersunk hole and the through hole in sequence and is threadedly connected to the annular housing 1.

[0040] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A gas flow detection device, characterized in that: include: An annular housing (1), a PCB board (2), a thermistor temperature sensor (4), two platinum resistance temperature sensors (3) and a constant current power supply (5); The PCB board (2) is fixed inside the annular housing (1), the constant current power supply (5), the thermistor temperature sensor (4) and two platinum resistance temperature sensors (3) are all installed on the PCB board (2), and the two platinum resistance temperature sensors (3) are located on both sides of the PCB board (2); The constant current power supply (5) is electrically connected to the thermistor temperature sensor (4) and the two platinum resistance temperature sensors (3) respectively, and the thermistor temperature sensor (4) and the two platinum resistance temperature sensors (3) are electrically connected to the control circuit on the PCB board (2) respectively.

2. The gas flow detection device according to claim 1, characterized in that: The PCB board (2) is located on the axial section of the annular housing (1).

3. The gas flow detection device according to claim 1, characterized in that: The control circuit comprises an MCU, a filtering and rectifying unit and a voltage detection unit; the thermistor temperature sensor (4) and two platinum resistance temperature sensors (3) are respectively electrically connected to the voltage detection unit; the voltage detection unit is electrically connected to the filtering and rectifying unit; and the filtering and rectifying unit is electrically connected to the MCU.

4. The gas flow detection device according to claim 3, characterized in that: The control circuit also includes a wireless transmission unit, which is electrically connected to the MCU and is used to transmit the calculated gas flow to a remote server or a mobile client.

5. The gas flow detection device according to claim 1, characterized in that: The inner wall of the annular housing (1) is symmetrically provided with receiving grooves on both sides for receiving the PCB board (2); one end of the annular housing (1) is provided with notches at a position corresponding to the receiving groove for the PCB board (2) to enter and exit the receiving groove; at least one countersunk hole communicating with the receiving groove is provided at a position corresponding to each receiving groove on the annular housing (1); a bolt (6) for fixing the annular housing (1) and the PCB board (2) is passed through the countersunk hole.

6. The gas flow detection device according to claim 5, characterized in that: The front end of the bolt (6) extends out of the countersunk hole and is threadedly connected to the PCB board (2).

7. The gas flow detection device according to claim 6, characterized in that: A through hole for the bolt (6) to pass through is provided at a position corresponding to the PCB board (2) and the bolt (6); the front end of the bolt (6) passes through the countersunk hole and the through hole in sequence and is threadedly connected to the annular housing (1).

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