Gas flowmeter

Abstract

The utility model relates to the technical field of circuit design, in particular to a gas flow meter, which comprises an MCU (Microprogrammed Control Unit) module, a CAN (Controller Area Network) communication module, a power supply module and a flow meter module, and the flow meter module, the CAN communication module and the power supply module are respectively and electrically connected with the MCU module. According to the design, two flowmeter modules are included, formula fitting calculation is carried out by measuring the pressure difference of two sensors and combining the environment temperature, accurate gas flow data are obtained, the accuracy and reliability of measurement are improved, and the device is suitable for various complex working environments; by optimizing circuit design and module combination, high-precision gas flow measurement is achieved, and the gas flow meter is high in stability and reliability, easy to maintain and suitable for various industrial and daily application scenes.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit design, in particular to a gas flow meter. Background Art

[0002] Gas flow meters play a vital role in industrial production and everyday life. Their primary function is to accurately measure gas flow to support process control, ensure safety, improve energy efficiency, protect the environment, and meet regulatory requirements. In fields such as chemical engineering, energy, and environmental protection, accurate gas flow measurement is crucial for optimizing processes, reducing resource waste, monitoring emissions, and ensuring fair trade. Furthermore, gas flow meters facilitate real-time monitoring and maintenance of equipment, promptly identifying issues and reducing maintenance costs. Therefore, gas flow meters have broad application value in improving production efficiency, ensuring operational safety, and complying with environmental standards.

[0003] Existing gas flow meters include differential pressure type, float type and thermal type, which have been widely used in various industries. However, thermal type gas flow meters have disadvantages such as small measurement range, easy damage and high cost. Float type gas flow meters are easily affected by the environment, and differential pressure gas flow meters are large in size.

[0004] Therefore, there is a need for a gas flow meter that can provide accurate measurement over a wider flow range. The gas flow meter needs to be more durable, reduce maintenance frequency, and have a more competitive price. At the same time, it needs to be smaller, easier to install and maintain, and suitable for application scenarios with limited space. Utility Model Content

[0005] The utility model aims to solve the problems of existing gas flow meters such as relatively narrow measurement range, easy damage, high cost and easy influence by environmental changes, and proposes a gas flow meter.

[0006] The utility model is achieved through the following technical solutions:

[0007] A gas flow meter, comprising an MCU module, a CAN communication module, a power module, and a flow meter module, wherein the flow meter module, the CAN communication module, and the power module are electrically connected to the MCU module respectively;

[0008] The MCU module includes a control chip U2, and the model of the control chip U2 is SWM181CBT6;

[0009] The flow meter module includes a flow sensor chip U3, the model of which is BMP390L;

[0010] Pin 2 of the flow sensor chip U3 is connected to pin 43 of the control chip U2, pin 4 of the flow sensor chip U3 is connected to pin 44 of the control chip U2, and pin 7 of the flow sensor chip U3 is connected to pin 42 of the control chip U2;

[0011] Pin 1 of the flow sensor chip U3 is respectively connected to the power module, pin 6 of the flow sensor chip U3, one end of the resistor FB1, and one end of the capacitor C9. The other end of the capacitor C9 is respectively connected to one end of the capacitor C10, pins 3, 8, and 9 of the flow sensor chip U3 and then grounded. The other end of the capacitor C10 is respectively connected to the other end of the resistor FB1 and pin 10 of the flow sensor chip U3.

[0012] Furthermore, there are two flow meter modules, and the two flow meter modules are electrically connected to the MCU module respectively.

[0013] Furthermore, the CAN communication module includes a communication chip U1, the model of the communication chip U1 is SIT65HVD233DR, pin 1 of the communication chip U1 is connected to pin 9 of the control chip U2, pin 4 of the communication chip U1 is connected to pin 8 of the control chip U2, pin 6 of the communication chip U1 is respectively connected to one end of the TVS diode D2, one end of the TVS diode D3, and the CANL bus end, and pin 7 of the communication chip U1 is respectively connected to the other end of the TVS diode D2, one end of the TVS diode D1, and the CANH bus end.

[0014] Furthermore, the TVS diode is a bidirectional TVS diode.

[0015] Furthermore, the power supply module includes a power supply chip U4, the model of the power supply chip U4 is SSP7603P30M5R, and pin 1 of the power supply chip U4 is respectively connected to the cathode of the diode D4, the cathode of the diode D5, one end of the capacitor C11, and one end of the capacitor C12. The anode of the diode D4 is connected to the 5V voltage input end, and pin 5 of the power supply chip U4 is respectively connected to one end of the capacitor C13 and one end of the capacitor C14. Pin 5 of the power supply chip U4 outputs a +3V voltage.

[0016] Beneficial effects of the utility model:

[0017] (1) This utility model proposes a gas flow meter that uses a BMP390L flow sensor chip. The design includes two flow meter modules. By measuring the pressure difference between the two sensors and performing a formula fitting calculation based on the ambient temperature, accurate gas flow data is obtained. This design improves the accuracy and reliability of the measurement and is suitable for various complex working environments.

[0018] (2) The utility model proposes a gas flow meter that uses the SWM181CBT6 control chip and is equipped with a 24MHz passive crystal oscillator to provide a stable clock source. The MCU circuit module includes SWD and UART debugging interfaces, which are convenient for development and debugging. At the same time, the external LED control signal provides users with a simple and intuitive status indication function.

[0019] (3) The gas flow meter proposed in this utility model adopts the SIT65HVD233DR communication chip to achieve efficient data transmission between external devices and MCU. The use of the CAN communication interface ensures the stability and real-time performance of data transmission, supports remote monitoring and data reading, and the application of the bidirectional TVS diode further enhances the anti-interference ability and electrical protection of the communication module.

[0020] (4) The gas flow meter proposed in this utility model realizes high-precision gas flow measurement by optimizing circuit design and module combination. It has high stability, reliability and easy maintenance, and is suitable for a variety of industrial and daily application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 This is a circuit block diagram of a gas flow meter proposed in the utility model;

[0023] Figure 2 This is a circuit schematic diagram of the MCU module of a gas flow meter proposed in this utility model;

[0024] Figure 3 This is a circuit schematic diagram of a CAN communication module of a gas flow meter proposed in this utility model;

[0025] Figure 4 This is a circuit schematic diagram of a power module of a gas flow meter proposed in the utility model;

[0026] Figure 5 This is a circuit schematic diagram of a flow meter module of a gas flow meter proposed in the present utility model;

[0027] Figure 6 This is a cross-sectional view of a gas flow meter proposed in the present utility model;

[0028] In the figure, 1-pressure sensor 1, 2-pressure sensor 2, 3-45° inclined plane. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The schematic implementation methods of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1

[0031] refer to Figure 1-Figure 5 A gas flow meter includes an MCU module, a CAN communication module, a power module, and a flow meter module, wherein the flow meter module, the CAN communication module, and the power module are electrically connected to the MCU module. The MCU module includes a control chip U2, the model of which is SWM181CBT6. This chip serves as the core of the entire gas flow meter and is responsible for processing signals and data from the flow meter module, the CAN communication module, and the power module. The SWM181CBT6 chip has the characteristics of high performance and low power consumption, and is suitable for complex gas flow measurement and control tasks. To ensure the stable operation of the MCU module, a 24MHz passive crystal oscillator is installed in the design. The crystal oscillator provides a stable clock source, ensuring the high-precision timing and data processing capabilities of the MCU. The choice of a passive crystal oscillator reduces the number of external components and improves the reliability and stability of the system. To facilitate development and debugging, the MCU module reserves SWD and UART debugging interfaces. The SWD interface provides a simple and efficient debugging method, supports single-step debugging and breakpoint setting, and the UART interface is used for serial communication, facilitating data transmission and the output of debugging information. In this embodiment, the MCU module can also be connected to an external LED control signal for status indication and information transmission. The MCU controls the LED's blinking frequency and pattern to convey system status and fault information to the user. This includes, but is not limited to, fast blinking indicating system operation and slow blinking indicating standby. This design allows users to intuitively understand the device's operating status, enhancing the user experience.

[0032] The flow meter module includes a first flow sensor chip U3 and a second flow sensor chip U5. The model of the first flow sensor chip U3 is BMP390L; pin 2 of the first flow sensor chip U3 is connected to pin 43 of the control chip U2, pin 4 of the first flow sensor chip U3 is connected to pin 44 of the control chip U2, and pin 7 of the first flow sensor chip U3 is connected to pin 42 of the control chip U2; pin 1 of the first flow sensor chip U3 is respectively connected to the power module, pin 6 of the first flow sensor chip U3, one end of the resistor FB1, and one end of the capacitor C9. The other end of the capacitor C9 is respectively connected to one end of the capacitor C10, pins 3, 8 and 9 of the first flow sensor chip U3 and then grounded. The other end of the capacitor C10 is respectively connected to the other end of the resistor FB1 and pin 10 of the first flow sensor chip U3.

[0033] The model of the second flow sensor chip U5 is BMP390L; pin 2 of the second flow sensor chip U5 is connected to pin 43 of the control chip U2, pin 4 of the second flow sensor chip U5 is connected to pin 44 of the control chip U2, and pin 7 of the second flow sensor chip U5 is connected to pin 41 of the control chip U2; pin 1 of the second flow sensor chip U5 is respectively connected to the power module, pin 6 of the second flow sensor chip U5, one end of the resistor FB2, and one end of the capacitor C15, the other end of the capacitor C15 is respectively connected to one end of the capacitor C16, pins 3, 8 and 9 of the second flow sensor chip U5 and then grounded, and the other end of the capacitor C16 is respectively connected to the other end of the resistor FB2 and pin 10 of the second flow sensor chip U5.

[0034] In this embodiment, two BMP390L flow sensor chips are used to measure the pressure at two different points respectively. By acquiring the pressure data of the first flow sensor chip U3 and the second flow sensor chip U5, the pressure difference between the two points can be obtained. The BMP390L sensor chip can not only measure pressure, but also measure the ambient temperature. The ambient temperature data obtained by these two sensor chips can be used to monitor and compensate for changes in ambient temperature in real time. The control chip SWM181CBT6 in the MCU module is used to calculate the pressure difference between the two sensors, and the formula is fitted in combination with the real-time ambient temperature data. Through formula fitting, the current gas flow rate can be accurately calculated.

[0035] The CAN communication module includes a communication chip U1, the model of which is SIT65HVD233DR. Pin 1 of the communication chip U1 is connected to pin 9 of the control chip U2, pin 4 of the communication chip U1 is connected to pin 8 of the control chip U2, pin 6 of the communication chip U1 is respectively connected to one end of the bidirectional TVS diode D2, one end of the bidirectional TVS diode D3, and the CANL bus end, and pin 7 of the communication chip U1 is respectively connected to the other end of the bidirectional TVS diode D2, one end of the bidirectional TVS diode D1, and the CANH bus end.

[0036] In this embodiment, the communication method adopted is a bus-based communication protocol, namely CAN communication. The CAN communication has a high communication rate and strong anti-interference ability. The communication chip SIT65HVD233DR is responsible for converting the data of the MCU module into a CAN bus signal, so that external devices can exchange data with the MCU through the CAN bus.

[0037] By connecting pins 1 and 4 of U1 to pins 9 and 8 of the control chip U2, respectively, effective data communication between the MCU and the communication chip is achieved. The use of bidirectional TVS diodes (D2, D3, and D1) further enhances the CAN communication module's anti-interference capabilities and electrical protection. Bidirectional TVS diodes D2 and D3 are connected to pins 6 (CANL) and 7 (CANH) of the communication chip U1, respectively, protecting the CAN bus from high-voltage transients. Bidirectional TVS diode D1, along with bidirectional TVS diodes D2 and D3, form a protective circuit that prevents electrical overloads from damaging the communication chip and bus.

[0038] The CAN communication module allows remote devices to access and control the gas flow meter through the CAN bus, realizing remote monitoring functions.

[0039] Through the CAN bus, external devices can read gas flow data in real time and adjust and control the working status of the flow meter as needed. The real-time nature and efficient transmission of data ensure that external devices can quickly respond to and process the data provided by the flow meter.

[0040] The power supply module includes a power supply chip U4, the model of which is SSP7603P30M5R. Pin 1 of the power supply chip U4 is respectively connected to the cathode of the diode D4, the cathode of the diode D5, one end of the capacitor C11, and one end of the capacitor C12. The anode of the diode D4 is connected to the 5V voltage input end. Pin 5 of the power supply chip U4 is respectively connected to one end of the capacitor C13 and one end of the capacitor C14. Pin 5 of the power supply chip U4 outputs a +3V voltage.

[0041] In this embodiment, diodes D4 and D5 protect the circuit, preventing reverse current from damaging the power supply chip and other components. Capacitors C11 and C12 provide filtering, while capacitors C13 and C14 further smooth the output voltage, reducing high-frequency noise and transient interference in the power supply. C11 and C12 are connected in parallel between pin 1 of power supply chip U4 and ground, effectively filtering out input power noise. C13 and C14 are connected in parallel between pin 5 of power supply chip U4 and ground, smoothing the 3V output voltage and ensuring stable power supply.

[0042] The power supply chip SSP7603P30M5R is responsible for converting the 5V input voltage into a stable 3V output voltage. The chip has an efficient voltage conversion function and can provide a stable low-voltage power supply to meet the voltage requirements of the MCU and pressure sensor.

[0043] Example 2

[0044] This embodiment proposes a gas flow meter calibration method based on the first embodiment.

[0045] refer to Figure 6 The gas channel inside the gas flowmeter is designed to be larger at the front and smaller at the back, with a 45° slope in the middle. This design will cause the gas flow velocity to change when it flows through the channel due to the change in the channel cross-sectional area.

[0046] Therefore, two pressure sensors are arranged at different positions of the channel: pressure sensor 1 is located at a place where the channel cross-sectional area is S1, and the measured air pressure is P1; pressure sensor 2 is located at a place where the channel cross-sectional area is S2, and the measured air pressure is P2.

[0047] The Bernoulli equation describes the conservation of energy when a fluid flows in a pipe. For incompressible fluids, the Bernoulli equation can be simplified to:

[0048]

[0049] In horizontal flow, gravitational potential energy is neglected , we can get:

[0050]

[0051] According to the continuity equation :

[0052] ,

[0053] Substituting the velocity term into the Bernoulli equation and rearranging it, we get the expression for flow rate Q:

[0054]

[0055] Density of gas It will change with temperature. Therefore, the density needs to be calibrated to ensure the accuracy of the calculation. In actual operation, it is necessary to:

[0056] Measure temperature, use temperature sensor to measure gas temperature in real time;

[0057] Adjust density, adjust gas density according to the measured temperature The value of

[0058] Recalculate the flow rate and recalculate the gas flow rate Q using the calibrated density value.

[0059] Through the above design and calculation methods, this gas flowmeter can accurately measure gas flow. The channel design, pressure sensor placement, and application of the Bernoulli equation enable the system to calculate flow rate based on pressure differential and cross-sectional area change. Temperature calibration further improves measurement accuracy and reliability.

[0060] The above shows and describes the basic principles and main features of the present utility model and the advantages of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present utility model. Various changes and improvements are possible without departing from the spirit and scope of the present utility model. Such changes and improvements are within the scope of the present utility model. The scope of protection claimed in the present utility model is defined by the appended claims and their equivalents.

Claims

1. A gas flow meter, comprising an MCU module, a CAN communication module, and a power module, characterized in that: It also includes a flow meter module, wherein the flow meter module, the CAN communication module, and the power supply module are electrically connected to the MCU module respectively; The MCU module includes a control chip U2, and the model of the control chip U2 is SWM181CBT6; The flow meter module includes a flow sensor chip U3, the model of which is BMP390L; Pin 2 of the flow sensor chip U3 is connected to pin 43 of the control chip U2, pin 4 of the flow sensor chip U3 is connected to pin 44 of the control chip U2, and pin 7 of the flow sensor chip U3 is connected to pin 42 of the control chip U2; Pin 1 of the flow sensor chip U3 is respectively connected to the power module, pin 6 of the flow sensor chip U3, one end of the resistor FB1, and one end of the capacitor C9. The other end of the capacitor C9 is respectively connected to one end of the capacitor C10, pins 3, 8, and 9 of the flow sensor chip U3 and then grounded. The other end of the capacitor C10 is respectively connected to the other end of the resistor FB1 and pin 10 of the flow sensor chip U3.

2. A gas flow meter according to claim 1, characterized in that: There are two flow meter modules, and the two flow meter modules are electrically connected to the MCU module respectively.

3. A gas flow meter according to claim 1, characterized in that: The CAN communication module includes a communication chip U1, the model of the communication chip U1 is SIT65HVD233DR, pin 1 of the communication chip U1 is connected to pin 9 of the control chip U2, pin 4 of the communication chip U1 is connected to pin 8 of the control chip U2, pin 6 of the communication chip U1 is respectively connected to one end of the TVS diode D2, one end of the TVS diode D3, and the CANL bus end, and pin 7 of the communication chip U1 is respectively connected to the other end of the TVS diode D2, one end of the TVS diode D1, and the CANH bus end.

4. A gas flow meter according to claim 3, characterized in that: The TVS diode is a bidirectional TVS diode.

5. A gas flow meter according to claim 1, characterized in that: The power supply module includes a power supply chip U4, the model of which is SSP7603P30M5R. Pin 1 of the power supply chip U4 is respectively connected to the cathode of the diode D4, the cathode of the diode D5, one end of the capacitor C11, and one end of the capacitor C12. The anode of the diode D4 is connected to the 5V voltage input end. Pin 5 of the power supply chip U4 is respectively connected to one end of the capacitor C13 and one end of the capacitor C14. Pin 5 of the power supply chip U4 outputs a +3V voltage.

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