Airflow detection device based on piezoelectric film and electronic atomizer

Abstract

The utility model discloses an airflow detection device based on a piezoelectric film and an electronic atomizer. The airflow detection device comprises an airflow channel and the piezoelectric film covering the air outlet end of the airflow channel. The air inlet end of the airflow channel is further provided with a turbulent flow generating structure, one end of the piezoelectric film is fixed in the airflow channel to serve as a fixed end, and turbulent flow formed when airflow passes through the turbulent flow generating structure can enable the other end of the piezoelectric film to swing around the fixed end of the piezoelectric film. According to the airflow detection device and the electronic atomizer, the turbulent flow generation structure is arranged at the air inlet end of the airflow channel, stable airflow entering the airflow channel is changed to be in a turbulent flow state, and the turbulent flow enables the piezoelectric film to vibrate, so that the problem that the piezoelectric film cannot accurately generate an electric signal in a stable state is solved; and the accuracy and reliability of the airflow detection device in airflow detection are improved.

Description

Technical Field

[0001] This application relates to the field of sensing and detection technology, and in particular to an airflow detection device and an electronic atomizer based on a piezoelectric thin film. Background Technology

[0002] Airflow detection has a wide range of applications, such as medical drug inhalation, automated oxygen delivery, and electronic cigarettes, and generally employs capacitive membranes, resistive membranes, and MEMS (Mechanical and Electrical Systems). Capacitive membranes are widely used due to their price advantage, but they have some drawbacks. For example, if grease or other foreign matter adheres to them during operation, it can lead to false detections and problems. MEMS devices suffer from the problem of foreign matter clogging the pores. Resistive membranes have sensitivity limitations. Piezoelectric films can avoid interference from oil contaminants, but their characteristics mean they cannot obtain an effective signal under stable airflow conditions, thus hindering accurate detection. Utility Model Content

[0003] This application discloses an airflow detection device and an electronic atomizer based on a piezoelectric thin film. The airflow is detected by using a piezoelectric thin film and combined with an airflow channel design, which solves the drawbacks of the prior art and is not easily affected by external contamination.

[0004] An airflow detection device based on a piezoelectric thin film includes an airflow channel and a piezoelectric thin film covering the outlet end of the airflow channel. The inlet end of the airflow channel is also provided with a turbulence generating structure. One end of the piezoelectric thin film is fixed inside the airflow channel as a fixed end. The turbulence generated by the airflow passing through the turbulence generating structure can cause the other end of the piezoelectric thin film to swing around its fixed end.

[0005] Furthermore, the turbulence generating structure includes a columnar body and two baffles; the two ends of the columnar body are fixed to the inner wall of the airflow channel, dividing the airflow channel into a first flow channel and a second flow channel; one end of the baffle is fixed to the inner wall of the airflow channel, and the other end extends towards the middle of the airflow channel and is inclined towards the direction of the columnar body, dividing the airflow channel into a first bend and a second bend, so that the airflow passing through the first flow channel needs to pass through the first bend and the second bend to reach the piezoelectric film, while the airflow passing through the second flow channel only needs to pass through the second bend to reach the piezoelectric film.

[0006] Furthermore, the two baffles are a first baffle and a second baffle; the extension length of the first baffle is three-quarters of the inner diameter of the airflow channel, the first included angle formed between the first baffle and the inner wall of the airflow channel is between 45 degrees and 90 degrees, and the opening of the first included angle faces the direction of the columnar body; the second included angle formed between the second baffle and the inner wall of the airflow channel is between 45 degrees and 90 degrees, and the opening of the second included angle faces the direction of the columnar body and the first baffle.

[0007] Furthermore, the central cross-section of the columnar body is circular, with the center of the circle located on the center line of the airflow channel, and the diameter of the circle is larger than the inner diameter of the airflow channel.

[0008] Furthermore, the airflow channel includes a long axis section and a horn section. One end of the long axis section is connected to the small opening end of the horn section, the large opening end of the horn section serves as the air outlet end of the airflow channel, and the other end of the long axis section serves as the air inlet end of the airflow channel. The piezoelectric film is disposed in the horn section. The columnar body, the first baffle, and the second baffle are disposed in the long axis section and are arranged sequentially along the airflow direction.

[0009] Furthermore, the airflow detection device also includes an airflow detection circuit, which includes a DC blocking capacitor, an integrating circuit, and a processor. The DC blocking capacitor is connected to the piezoelectric film and is used to filter out the DC component in the electrical signal generated by the deformation of the piezoelectric film. The integrating circuit is connected to the DC blocking capacitor and is used to receive the signal output by the DC blocking capacitor and convert it into a detection voltage output to the processor.

[0010] Furthermore, the integrating circuit includes an operational amplifier, an integrating resistor, and an integrating capacitor. The inverting input of the operational amplifier is connected to the DC blocking capacitor through the integrating resistor. The non-inverting input of the operational amplifier is connected to and receives the reference voltage output by the processor. The two ends of the integrating capacitor are respectively connected to the inverting input and the output of the operational amplifier. The output of the operational amplifier is connected to the detection receiving end of the processor.

[0011] Furthermore, the airflow detection circuit also includes an offset resistor, the two ends of which are respectively connected to the inverting input terminal and the output terminal of the operational amplifier.

[0012] Furthermore, the airflow detection circuit also includes a discharge switch, the two ends of which are respectively connected to the two ends of the integrating capacitor; the processor is also connected to the discharge switch to control the on / off state of the discharge switch.

[0013] An electronic atomizer includes the aforementioned airflow detection device, wherein the electronic atomizer includes a cavity in which the airflow channel is provided.

[0014] The airflow detection device and electronic atomizer described in this application change the steady airflow entering the airflow channel into a turbulent state by setting a turbulence generating structure at the air inlet end of the airflow channel. The turbulence causes the piezoelectric film to vibrate, thereby solving the problem that the piezoelectric film cannot accurately generate electrical signals in a stable state, and improving the accuracy and reliability of the airflow detection device for airflow detection. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the airflow detection device according to an embodiment of this application.

[0016] Figure 2 This is a circuit diagram of an airflow detection device according to an embodiment of this application. Detailed Implementation

[0017] The embodiments of this application will now be described in detail with reference to the accompanying drawings. These drawings, as part of the disclosure of this application, are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of this application.

[0018] like Figure 1 As shown, an airflow detection device based on a piezoelectric thin film is disclosed. The piezoelectric thin film T1 is a sensor that converts mechanical energy into electrical energy using the piezoelectric effect. When the piezoelectric thin film T1 is deformed under force, an electrical signal is generated between the upper and lower electrode surfaces of the film, and the signal magnitude changes proportionally to the magnitude of the deformation. While general piezoelectric materials are sensitive to pressure, for the piezoelectric thin film T1, a small force applied longitudinally generates a large stress transversely. However, if the same force is applied to a large area of ​​the film, the resulting stress is much smaller. Therefore, the piezoelectric thin film T1 is highly sensitive to dynamic stress. In the airflow detection device, the piezoelectric thin film T1 is used to deform under the action of airflow and generate an electrical signal. The airflow detection device includes an airflow channel and the piezoelectric thin film T1 covering the outlet end of the airflow channel. The air inlet end of the airflow channel is also equipped with a turbulence generating structure. One end of the piezoelectric film T1 is fixed inside the airflow channel as a fixed end. When the airflow passes through the turbulence generating structure, turbulence is generated. This turbulence causes the other end of the piezoelectric film T1 to oscillate around its fixed end, thereby generating an electrical signal. In this embodiment, the airflow detection device, by setting a turbulence generating structure at the air inlet end of the airflow channel, changes the steady airflow entering the airflow channel into a turbulent state. The turbulence causes the piezoelectric film T1 to vibrate, thus solving the problem that the piezoelectric film T1 cannot accurately generate an electrical signal in a stable state, improving the accuracy and reliability of the airflow detection device.

[0019] In one embodiment, the turbulence generating structure includes a columnar body Y1 and two baffles. The two ends of the columnar body Y1 are fixed to the inner wall of the airflow channel, dividing the airflow channel into a first flow channel and a second flow channel, as shown below. Figure 1As shown, the channel formed between the right side of the circular cross-section of columnar body Y1 and the inner wall of the right side of the airflow channel is the first flow channel, and the channel formed between the left side of the circular cross-section of columnar body Y1 and the inner wall of the left side of the airflow channel is the second flow channel. One end of the baffle is fixed to the inner wall of the airflow channel, and the other end extends towards the middle of the airflow channel and is inclined towards the location of columnar body Y1, dividing the airflow channel into a first bend and a second bend. This means that the airflow passing through the first flow channel needs to pass through the first bend and the second bend to reach the piezoelectric film T1, while the airflow passing through the second flow channel only needs to pass through the second bend to reach the piezoelectric film T1. This makes the airflow reaching the piezoelectric film T1 turbulent, thereby forcing the piezoelectric film T1 to vibrate or oscillate irregularly, effectively generating an electrical signal.

[0020] As one implementation method, such as Figure 1 As shown, the two baffles are a first baffle D1 and a second baffle D2. The extension length of the first baffle D1 is three-quarters of the inner diameter of the airflow channel. The first angle formed between the first baffle D1 and the inner wall of the airflow channel is between 45 degrees and 90 degrees, preferably 60 degrees, and the opening of the first angle faces the direction of the columnar body Y1. The second angle formed between the second baffle D2 and the inner wall of the airflow channel is between 45 degrees and 90 degrees, preferably 60 degrees, and the opening of the second angle faces the direction of the columnar body Y1 and the first baffle D1. Through this staggered and orderly arrangement structure, the incoming airflow can form a more obvious turbulent state, effectively avoiding structural failure caused by turbulence, which leads to inaccurate detection by the airflow detection device.

[0021] As one implementation method, such as Figure 1 As shown, the central cross-section of the columnar body Y1 is circular, with the center of the circle located on the center line of the airflow channel, and the diameter of the circle is larger than the inner diameter of the airflow channel. This allows the incoming steady airflow to undergo a certain degree of scaling, increasing the impact force of the airflow and making the subsequent turbulence effect more pronounced.

[0022] As one implementation method, such as Figure 1 As shown, the airflow channel includes a long axis section and a horn section. Two parallel vertical lines in the figure represent the long axis section, with its lower end serving as the air inlet of the airflow channel and its upper end connecting to the small opening of the horn section. Two lines opening upwards in a V-shape represent the horn section, with its large opening serving as the air outlet of the airflow channel. The vertically upward arrows in the figure indicate the airflow direction. The piezoelectric film T1 is disposed in the horn section; the columnar body Y1, the first baffle D1, and the second baffle D2 are disposed in the long axis section and arranged sequentially along the airflow direction. Airflow detection devices using this structure provide more reliable and accurate detection results.

[0023] As one implementation method, such as Figure 2 As shown, the airflow detection device further includes an airflow detection circuit M1, which comprises a DC blocking capacitor C2, an integrating circuit, and a processor Z1. The DC blocking capacitor C2 is connected to the piezoelectric film T1 and is used to filter out the DC component in the electrical signal generated by the deformation of the piezoelectric film T1. The integrating circuit is connected to the DC blocking capacitor C2 and is used to receive the signal output by the DC blocking capacitor C2 and convert it into a detection voltage output to the processor Z1. The processor Z1 can be a control chip such as an MCU, DSP, or FPGA capable of data or signal processing.

[0024] The integrating circuit includes an operational amplifier U1, an integrating resistor R2, and an integrating capacitor C1. The inverting input of the operational amplifier U1 is connected to the DC blocking capacitor C2 through the integrating resistor R2. The non-inverting input of the operational amplifier U1 is connected to and receives the reference voltage Vref output by the processor Z1. The two ends of the integrating capacitor C1 are connected to the inverting input and the output Vout of the operational amplifier U1, respectively. The output Vout of the operational amplifier U1 is connected to the detection receiver of the processor Z1.

[0025] When the piezoelectric film T1 deforms under the force of turbulence, it generates a certain amount of charge. This charge forms an electrical signal that is transmitted to the integrating circuit through the DC blocking capacitor C2. After processing the signal, the integrating circuit generates a stable output voltage at its output terminal Vout. This voltage is the detection voltage output by the airflow detection circuit M1. While the deformation persists, the charge remains constant, generally considered stable for about ten seconds, thus maintaining a constant output detection voltage that reflects the deformation of the piezoelectric film T1. When the deformation of the piezoelectric film T1 recovers, an opposite charge is generated and coupled to the integrating capacitor C1 through the DC blocking capacitor C2, thus canceling it out and restoring the output detection voltage to its initial value.

[0026] The airflow detection circuit M1 converts the charge change of the piezoelectric film T1 into a stable voltage output, thereby determining the magnitude of the deformation of the piezoelectric film T1 and consequently detecting the airflow. For example, in an aerosol device, airflow is generated when the user inhales, causing the piezoelectric film T1 to continuously deform. The airflow detection circuit M1 converts the charge generated by this deformation into a fixed output voltage, indicating that the aerosol device has detected airflow. Without the processing of the airflow detection circuit M1, only a transient electrical signal is detected, making it difficult for the processor Z1 to determine the current airflow state.

[0027] In one embodiment, the airflow detection circuit M1 further includes an offset resistor R1, the two ends of which are connected to the inverting input and output Vout of the operational amplifier U1, respectively. The offset resistor R1 is a large resistor, which can prevent the operational amplifier U1 from becoming offset.

[0028] In one embodiment, the airflow detection circuit M1 further includes a discharge switch K1, the two ends of which are respectively connected to the two ends of the integrating capacitor C1; the processor Z1 is also connected to the discharge switch K1 to control the on and off of the discharge switch K1, thereby realizing the initial discharge of the airflow detection circuit M1.

[0029] This application also discloses an electronic atomizer, including the aforementioned airflow detection device. The electronic atomizer includes a cavity with the airflow channel inside. By incorporating a turbulence-generating structure at the air inlet end of the airflow channel, the electronic atomizer transforms the steady airflow entering the channel into a turbulent state. This turbulence causes the piezoelectric film T1 to vibrate, thereby solving the problem that the piezoelectric film T1 cannot accurately generate electrical signals in a stable state, and improving the accuracy and reliability of the airflow detection device.

[0030] When the e-atomizer is powered on and begins operation, the processor Z1 sends a control signal to close the discharge switch K1 for initial discharge. After the discharge, the e-atomizer begins real-time monitoring. When airflow enters the airflow channel and forms turbulence through the turbulence generator, reaching the piezoelectric film T1, the piezoelectric film T1 deforms. The resulting electrical signal is transmitted to the integrating circuit through the DC blocking capacitor C2. After processing the electrical signal, the integrating circuit generates a stable detection voltage at its output terminal Vout. Upon receiving this detection voltage, the processor Z1 determines that the piezoelectric film T1 has deformed, indicating that the user is using the e-atomizer. At this point, the processor Z1 immediately controls the heating wire or atomizing plate to start working, atomizing the liquid so that the atomized gas flows out with the airflow, thus realizing the atomization function of the electronic device.

[0031] The above embodiments are only for illustrating the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be used to limit the scope of protection of this application. All equivalent transformations or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.

Claims

1. An airflow detection device based on a piezoelectric thin film, comprising an airflow channel and a piezoelectric thin film covering the outlet end of the airflow channel, characterized in that: The air inlet end of the airflow channel is also provided with a turbulence generating structure. One end of the piezoelectric film is fixed in the airflow channel as a fixed end. The turbulence generated by the airflow passing through the turbulence generating structure can cause the other end of the piezoelectric film to swing around its fixed end.

2. The airflow detection device according to claim 1, characterized in that: The turbulence generating structure includes a columnar body and two baffles. The two ends of the columnar body are fixed to the inner wall of the airflow channel, dividing the airflow channel into a first flow channel and a second flow channel. One end of the baffle is fixed to the inner wall of the airflow channel, and the other end extends towards the middle of the airflow channel and is inclined towards the columnar body, dividing the airflow channel into a first bend and a second bend. This allows the airflow passing through the first flow channel to reach the piezoelectric film by passing through the first bend and the second bend, while the airflow passing through the second flow channel only needs to pass through the second bend to reach the piezoelectric film.

3. The airflow detection device according to claim 2, characterized in that: The two baffles are the first baffle and the second baffle, respectively; The first baffle extends for three-quarters of the inner diameter of the airflow channel. The first angle formed between the first baffle and the inner wall of the airflow channel is between 45 degrees and 90 degrees, and the opening of the first angle faces the direction of the column. The second angle formed between the second baffle and the inner wall of the airflow channel is between 45 degrees and 90 degrees, and the opening of the second angle faces the direction of the column and the first baffle.

4. The airflow detection device according to claim 2, characterized in that: The central cross-section of the column is circular, with the center of the circle located on the center line of the airflow channel, and the diameter of the circle is larger than the inner diameter of the airflow channel.

5. The airflow detection device according to claim 3, characterized in that: The airflow channel includes a long axis section and a horn section. One end of the long axis section is connected to the small end of the horn section, the large end of the horn section serves as the air outlet of the airflow channel, and the other end of the long axis section serves as the air inlet of the airflow channel. The piezoelectric film is disposed in the horn section; The columnar body, the first baffle, and the second baffle are provided with long axis sections and are arranged sequentially along the airflow direction.

6. The airflow detection device according to any one of claims 1 to 5, characterized in that: The airflow detection device further includes an airflow detection circuit, which includes a DC blocking capacitor, an integrating circuit, and a processor. The DC blocking capacitor is connected to the piezoelectric film and is used to filter out the DC component in the electrical signal generated by the deformation of the piezoelectric film. The integrating circuit is connected to the DC blocking capacitor and is used to receive the signal output by the DC blocking capacitor and convert it into a detection voltage output to the processor.

7. The airflow detection device according to claim 6, characterized in that: The integrating circuit includes an operational amplifier, an integrating resistor, and an integrating capacitor. The inverting input of the operational amplifier is connected to a DC blocking capacitor through the integrating resistor. The non-inverting input of the operational amplifier is connected to and receives a reference voltage output by the processor. The two ends of the integrating capacitor are connected to the inverting input and the output of the operational amplifier, respectively. The output of the operational amplifier is connected to the detection receiving end of the processor.

8. The airflow detection device according to claim 7, characterized in that: The airflow detection circuit also includes an offset resistor, the two ends of which are connected to the inverting input and output of the operational amplifier, respectively.

9. The airflow detection device according to claim 8, characterized in that: The airflow detection circuit also includes a discharge switch, the two ends of which are respectively connected to the two ends of an integrating capacitor; the processor is also connected to the discharge switch to control the on / off state of the discharge switch.

10. An electronic atomizer, comprising the airflow detection device according to any one of claims 1 to 9, characterized in that: The electronic atomizer includes a cavity, and the airflow channel is provided inside the cavity.

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