A smart face mask with air supply and its method

Abstract

This invention discloses an air-supplying smart face mask and its method, belonging to the field of personal protective equipment technology. The face mask includes a main body assembly consisting of a negative pressure intake chamber and a positive pressure air supply chamber physically isolated by an outer shell cover and an air inlet base. The method eliminates the pressure sensor, which is susceptible to interference from complex operating conditions, and directly utilizes a motor that performs the air supply function as a sensing actuator. Leveraging the aerodynamic coupling characteristics of the mechanical structure, a reference current is recorded under a steady-state flow field. After operation, the working current is collected at high frequency and the slope is calculated. A judgment threshold is corrected through dynamic sensitivity compensation. The breathing phase is determined based on the current trend and slope, and the speed is adjusted accordingly. This invention improves the reliability and durability of the system in dusty environments; optimizes the human-machine aerodynamic coupling characteristics, enhances the system's wearability, rapidly increases the speed to establish a safe positive pressure during inhalation, and decreases the speed during exhalation to reduce exhaust resistance, thus lowering the wearer's breathing resistance.

Description

Technical Field

[0001] This invention relates to the field of personal protective equipment, specifically to an air-purifying smart face mask and its method. Background Technology

[0002] In coal mines, chemical plants, and dusty work environments, supplied-air respirators are crucial for ensuring the respiratory safety of workers. Traditional electrically powered supplied-air filtering respirators typically employ a constant speed or constant setting control strategy, with the fan operating at a fixed power regardless of whether the wearer is inhaling, exhaling, or holding their breath. This operating method has significant drawbacks: First, when the wearer exhales, the continuous supplied airflow and exhaled airflow oppose each other inside the mask, leading to increased exhaust resistance and a sharp rise in internal exhaust resistance. Second, when the wearer inhales rapidly during vigorous exercise, the constant airflow may not be sufficient to meet the instantaneous peak flow demand, causing the positive pressure inside the mask to be disrupted, allowing external contaminants to leak in. Third, continuous high-power operation accelerates battery consumption and shortens the device's runtime. While existing technologies have attempted to add pressure sensors to detect breathing pressure, precision sensors are prone to failure under harsh conditions of dust and high humidity, and this also increases the structural complexity of the system.

[0003] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide an air-blowing smart face mask and its method to solve the problems mentioned in the background art. Specifically, the technical solution of this invention is as follows:

[0005] A breathing-following control method for an air-supply smart face mask, comprising:

[0006] S1. Set up an air-supply smart mask. The air-supply smart mask includes a mask body assembly that forms a negative pressure air intake chamber and a positive pressure air supply chamber physically isolated by the outer shell cover and the air inlet base, a brushless DC motor and centrifugal impeller located in the positive pressure air supply chamber, and a filter assembly connected to the negative pressure air intake chamber.

[0007] S2. Under steady-state flow field, a brushless DC motor is controlled by a pulse width modulation drive signal to drive the centrifugal impeller to rotate with a constant duty cycle, and the average current value under steady state is recorded as the steady-state reference current.

[0008] S3. After startup, the real-time operating current and commutation frequency of the brushless DC motor are collected at high frequency, a time window queue is established to store the data, and the slope of the fitted line of the data in the queue is calculated.

[0009] S4. Perform dynamic sensitivity compensation: Calculate the difference between the steady-state reference current and the average load current under the current stable operating state, look up the preset impedance and compensation coefficient association table based on the difference, obtain the corresponding signal attenuation compensation coefficient, use the coefficient to correct the preset standard current fluctuation threshold, and generate a real-time judgment threshold.

[0010] S5. Adjust the rotation speed according to the changing trend, slope direction and real-time judgment threshold of the real-time working current: When the real-time working current shows a continuous upward trend, the slope is positive and the fluctuation amplitude exceeds the real-time judgment threshold, it is judged as the inhalation start segment and the pressure boosting strategy is executed; when the real-time working current shows a continuous downward trend, the slope is negative and the fluctuation amplitude exceeds the real-time judgment threshold, it is judged as the exhalation start segment and the pressure depressurization strategy is executed.

[0011] Preferably, in step S5, the step of implementing the boosting strategy includes:

[0012] Call the pre-stored pressure-flow-current-speed multidimensional characteristic mapping data model;

[0013] The current motor speed and operating current are input into the multidimensional characteristic mapping data model, and the real-time air pressure inside the mask is estimated through multidimensional interpolation calculation.

[0014] The deviation between the real-time air pressure value and the preset target micro-positive pressure value is calculated using a proportional-integral-derivative control algorithm.

[0015] Adjust the duty cycle of the pulse width modulation drive signal according to the deviation to increase the speed of the brushless DC motor until the real-time air pressure value reaches the target micro-positive pressure value.

[0016] Preferably, in step S5, the step of implementing the voltage reduction strategy includes:

[0017] Reduce the duty cycle of the pulse width modulation drive signal to control the brushless DC motor to decelerate to the standby speed that maintains the minimum ventilation volume, so as to reduce the collision resistance between the exhaled airflow and the supplied airflow.

[0018] Preferably, in step S4, the dynamic sensitivity compensation follows the following logic:

[0019] The difference is used to characterize the degree of blockage resistance in the flow channel;

[0020] The larger the difference, the smaller the corresponding signal attenuation compensation coefficient, and the lower the generated real-time judgment threshold, so as to improve the sensitivity of capturing weak respiratory signals under the condition of high flow channel impedance.

[0021] Preferably, during system operation, a filter clogging compensation step is also included:

[0022] Calculate the average current value over one respiratory cycle;

[0023] When the average current value shows a slow downward trend and it is confirmed by monitoring the breathing switching frequency that the wearer is not in a state of accelerated breathing rate, it is determined that the filter element in the filter assembly is dusty.

[0024] The pulse width modulation reference duty cycle is automatically increased to improve the overall speed range of the centrifugal impeller, thereby overcoming the air intake resistance caused by dust accumulation.

[0025] Preferably, in step S1, the physical isolation between the positive pressure air supply chamber and the negative pressure air intake chamber is achieved through the following methods:

[0026] An upward-protruding annular partition wall is provided on the upper surface of the air inlet base;

[0027] When the outer cover is fastened, its inner side is tightly pressed against the sealing rib at the top of the annular partition wall;

[0028] A negative pressure air intake chamber is formed in the outer area of ​​the annular partition wall, and a positive pressure air supply chamber is formed in the inner area of ​​the annular partition wall.

[0029] Preferably, in step S1, the filter assembly includes a waterproof box base connected to both sides of the air inlet base by snap-fit. The mating surface between the waterproof box base and the air inlet base is provided with a plastic elastomer sealing coating layer, which forms an airtight flow channel after being pressed.

[0030] A smart face mask with air supply, comprising:

[0031] The main component of the mask consists of an outer shell cover and an air inlet base, and the interior is divided into a negative pressure intake chamber and a positive pressure air supply chamber by an annular partition wall.

[0032] The air supply drive assembly includes a brushless DC motor located in a positive pressure air supply chamber and a centrifugal impeller fixed on the motor shaft;

[0033] The filter assembly is installed on both sides of the air inlet base and connected to the negative pressure air intake chamber;

[0034] The motherboard electrically connects the brushless DC motor to the battery.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] This invention eliminates the pressure sensor, which is susceptible to interference from complex operating conditions, and directly utilizes the motor that performs the air supply function as the sensing actuator. By leveraging the pneumatic coupling characteristics of the mechanical structure, the reliability and durability of the system in dusty environments are improved. It achieves millisecond-level breathing-following response, rapidly increasing the rotation speed to establish a safe positive pressure during inhalation and decreasing the rotation speed to reduce exhaust resistance during exhalation, thereby reducing the wearer's breathing resistance, optimizing the human-machine pneumatic coupling characteristics, and improving the system's wearability. Through low-power operation during the exhalation phase, it effectively reduces ineffective air supply work, extending the device's operating time with the same battery capacity. Attached Figure Description

[0037] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0038] Figure 1 This is a schematic diagram of the overall external structure of the mask;

[0039] Figure 2 This is a schematic diagram of the filter assembly;

[0040] Figure 3 This is a schematic diagram of the connection structure between the air supply drive component and the motherboard;

[0041] Figure 4 This is a schematic diagram of the process flow of the method of the present invention.

[0042] In the diagram: 10. Main mask assembly; 11. Outer shell cover; 12. Air inlet base; 13. Annular partition wall; 131. Sealing rib; 14. Negative pressure intake chamber; 15. Positive pressure air supply chamber; 20. Filter assembly; 21. Waterproof box base; 22. Sealing cover layer; 23. Filter element; 24. Buckle; 30. Air supply drive assembly; 31. Motor mounting cover; 32. Brushless DC motor; 33. Centrifugal impeller; 41. Main board; 411. Microcontroller unit; 412. Sampling resistor; 42. Battery. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0044] Example 1:

[0045] Please see Figure 1-4 This invention provides a breathing tracking control method for an air-purifying smart face mask, comprising:

[0046] S1. An air-supply smart mask is provided. The air-supply smart mask includes a mask body assembly 10, which is physically isolated by a negative pressure air intake chamber 14 and a positive pressure air supply chamber 15 formed by an outer shell cover 11 and an air inlet base 12; a brushless DC motor 32 and a centrifugal impeller 33 located in the positive pressure air supply chamber 15; and a filter assembly 20 connected to the negative pressure air intake chamber 14.

[0047] S2. Under steady-state flow field, the brushless DC motor 32 is controlled by pulse width modulation drive signal to drive the centrifugal impeller 33 to rotate with a constant duty cycle, and the average current value under steady state is recorded as steady-state reference current.

[0048] S3. After startup, the real-time operating current and commutation frequency of the brushless DC motor 32 are collected at high frequency, a time window queue is established to store the data, and the slope of the fitted line of the data in the queue is calculated.

[0049] The specific frequency range of high-frequency acquisition is from 1 kilohertz to 10 kilohertz to ensure that the transient current jump characteristics at the moment of respiration can be fully captured.

[0050] S4. Perform dynamic sensitivity compensation: Calculate the difference between the steady-state reference current and the average load current under the current stable operating state, look up the preset impedance and compensation coefficient association table based on the difference, obtain the corresponding signal attenuation compensation coefficient, use the coefficient to correct the preset standard current fluctuation threshold, and generate a real-time judgment threshold.

[0051] S5. Adjust the rotation speed according to the changing trend, slope direction and real-time judgment threshold of the real-time working current: When the real-time working current shows a continuous upward trend, the slope is positive and the fluctuation amplitude exceeds the real-time judgment threshold, it is judged as the inhalation start segment and the pressure boosting strategy is executed; when the real-time working current shows a continuous downward trend, the slope is negative and the fluctuation amplitude exceeds the real-time judgment threshold, it is judged as the exhalation start segment and the pressure depressurization strategy is executed.

[0052] The breathing-following control method of the air-supply smart mask in this embodiment addresses the problem that traditional masks cannot match the human breathing rhythm in constant airflow mode, leading to a sudden increase in breathing resistance or leakage. It utilizes the coupling characteristics of motor current and pneumatic load for sensorless control.

[0053] In the initial stage of the mask system startup, the breathing follow control method of the air-supply smart mask drives the brushless DC motor 32 through the control motherboard 41. For example, a 24V three-phase brushless motor is used to drive the centrifugal impeller 33 to rotate in a steady flow field without breathing interference. At this time, the initial resistance of the filter element 23 is relatively fixed. The system records the current value in this state as a reference to provide a reference zero point for subsequent identification of load changes.

[0054] Once operational, the breathing-following control method of the air-blowing smart mask utilizes the sampling resistor 412 and microcontroller 411 on the mainboard 41, such as an STM32F103 series microcontroller, to high-frequency read the bus current. Human breathing airflow directly alters the pressure environment within the flow channel, thereby changing the rotational resistance torque of the centrifugal impeller 33. This change in mechanical resistance is mapped to fluctuations in the motor current within milliseconds. The microcontroller 411 determines the trend direction of current change by calculating the slope of the fitted straight line of the current data.

[0055] The computational logic flow is as follows: the microcontroller unit 411 acquires continuous current samples at a fixed sampling frequency and pushes them into a circular queue; linear regression is performed on the sample points in the queue using the least squares method. Let the sampling window size be... ,For example The sampling point sequence is Then the slope of the fitted line Calculated using the following formula:

[0056]

[0057] The slope The positive or negative sign of the symbol is used as the input for determining the direction of breathing: when Time characterizes the upward trend of current, when The time characterizes the decreasing trend of the current;

[0058] In this calculation process, the setting of the judgment time and the real-time judgment threshold follows the signal-to-noise ratio priority principle: the system pre-determines the amplitude of the inherent current ripple generated by the commutation of the motor during steady-state operation; in order to prevent misjudgment, the slope judgment value is set to be greater than the rate of change caused by the inherent current ripple, so as to filter out the interference of the motor's electrical noise on the breathing signal at the algorithm level.

[0059] The slope judgment value is the real-time judgment threshold generated after correction based on the standard current fluctuation threshold, which is reflected in the slope dimension.

[0060] Considering that in actual dusty operations, the filter component 20 will gradually accumulate dust, leading to an increase in air intake resistance. This high resistance will physically attenuate the disturbance signal of the breathing airflow to the motor, resulting in a lag in system response. The breathing follow control method of the air-supply smart mask introduces a dynamic sensitivity compensation mechanism. By monitoring the difference between the load current and the reference current in real time, the degree of flow channel blockage is quantified, and the judgment threshold is adjusted accordingly to ensure that the system can automatically lower the judgment threshold to capture weak breathing signals when the filter element is blocked.

[0061] The signal attenuation compensation coefficient is a gain factor used to correct the standard current fluctuation threshold. It is used to quantify the degree of attenuation of aerodynamic disturbance signals by physical resistance. Its logical function is to dynamically scale the judgment threshold so that the system maintains a consistent trigger sensitivity under different blockage environments.

[0062] Once an inhalation is confirmed, the system rapidly increases its rotation speed to replenish the flow and establish positive pressure; once an exhalation is confirmed, the system reduces its rotation speed to reduce exhaust resistance. This control logic achieves the tracking of the human breathing phase without the need for an external pressure sensor, reducing the wearer's breathing work consumption and extending the battery's operating time.

[0063] In step S5, the steps for implementing the boost strategy include:

[0064] Call the pre-stored pressure-flow-current-speed multidimensional characteristic mapping data model;

[0065] The current motor speed and operating current are input into the multidimensional characteristic mapping data model, and the real-time air pressure inside the mask is estimated through multidimensional interpolation calculation.

[0066] The deviation between the real-time air pressure value and the preset target micro-positive pressure value is calculated using a proportional-integral-derivative control algorithm.

[0067] Adjust the duty cycle of the pulse width modulation drive signal according to the deviation to increase the speed of the brushless DC motor 32 until the real-time air pressure value reaches the target micro-positive pressure value.

[0068] The step of implementing the pressurization strategy in this embodiment aims to solve the problem that the negative pressure inside the mask during inhalation may cause external pollutants to leak in, and to achieve closed-loop pressure stabilization without introducing a physical pressure sensor.

[0069] The steps of executing the pressurization strategy rely on the motor aerodynamic characteristic database pre-established in the memory of the motherboard 41. This database was obtained through standard wind tunnel testing in a laboratory environment and covers the pressure and flow relationship of the specific model of fan at different speeds and currents. When it is determined to be the inhalation start stage, the microcontroller unit 411 uses the real-time collected motor speed and current as index variables and performs interpolation calculations in the multi-dimensional characteristic mapping data model to calculate the virtual air pressure value inside the current mask.

[0070] This model logically represents the energy conversion and conservation relationship between the motor's electrical energy input, mechanical torque output, and airflow aerodynamic load. Through this model, the system can transform the difficult-to-measure static pressure of the cavity into a logical combination function of easily monitored current and speed signals, thereby achieving sensorless pressure closed-loop control.

[0071] The construction process of this multidimensional characteristic mapping data model is as follows: In a standard wind tunnel laboratory environment, the system traverses the entire speed range of the motor and simulates different exhaust back pressures by adjusting the wind tunnel load valve; for each discrete speed point and back pressure point, the motor bus current value, air flow value, and cavity pressure value are recorded simultaneously; finally, the least squares method is used to perform surface fitting on the massive discrete data points collected, thereby generating a continuous lookup table that can cover all working conditions, and establishing a deterministic functional relationship with current and speed as inputs and pressure as output;

[0072] This virtual air pressure value is then fed as feedback into the proportional-integral-derivative (PID) control algorithm module. The controller compares this estimated real-time air pressure value with a preset safety target micro-positive pressure value to calculate the pressure deviation. The safety target micro-positive pressure value is typically set to 10 to 20 Pascals to balance protection and comfort. This deviation is then amplified by a proportional circuit to provide rapid response, accumulated by an integral circuit to eliminate steady-state error, and finally outputs the corrected control quantity.

[0073] The feedback is sent to the proportional-integral-derivative control program module of the microcontroller unit 411 inside the motherboard 41;

[0074] Based on this deviation, the pressure boosting strategy dynamically adjusts the duty cycle of the pulse width modulation output to the brushless DC motor 32. If the real-time air pressure is lower than the target value, the duty cycle increases, the motor accelerates, and the centrifugal impeller 33 pumps in more air to compensate for the pressure loss caused by suction. As the rotational speed increases, the estimated air pressure gradually approaches the target value, and the system enters a steady-state slightly positive pressure state. This virtual closed-loop control based on model estimation avoids the risk of reading drift from physical sensors when covered by dust or damp, ensuring the stability of the protective pressure.

[0075] In step S5, the steps for implementing the buck strategy include:

[0076] Reduce the duty cycle of the pulse width modulation drive signal to control the brushless DC motor 32 to decelerate to the standby speed that maintains the minimum ventilation volume, so as to reduce the collision resistance between the exhaled airflow and the supplied airflow.

[0077] The step of implementing the pressure reduction strategy in this embodiment is aimed at the phenomenon that when the wearer exhales, continuous strong airflow will cause excessive pressure inside the mask, difficulty in exhaust, and increased ineffective power consumption.

[0078] When the system determines that the wearer has entered the exhalation phase based on the current slope characteristics, the step of executing the pressure reduction strategy immediately intervenes in the motor control logic. The microcontroller unit 411 rapidly reduces the duty cycle of the pulse width modulation drive signal and sends a deceleration command to the brushless DC motor 32. The motor speed does not drop directly to zero, but rather falls back to the preset standby speed.

[0079] The standby speed setting is designed to maintain the minimum ventilation in the flow channel. Its function is to prevent the humid and hot gas produced by exhalation from condensing and fogging on the mask, while maintaining a slight positive pressure trend inside the mask relative to the external environment to prevent negative pressure backflow when the valve closes at the end of exhalation.

[0080] By actively reducing the rotation speed during the exhalation phase, the pressure-reducing strategy significantly minimizes the collision between the supplied airflow and the exhaled airflow within the confined space of the mask. This reduced airflow resistance directly lowers the peak respiratory work of the wearer and improves the dynamic matching between the air supply system and the human respiratory rhythm. Simultaneously, since exhalation typically occupies a large portion of the respiratory cycle, the motor's low-power operation during this period significantly reduces battery power consumption, allowing the device to support longer operation times with the same battery capacity.

[0081] In step S4, dynamic sensitivity compensation follows the following logic:

[0082] The difference is used to characterize the degree of blockage resistance in the flow channel;

[0083] The larger the difference, the smaller the corresponding signal attenuation compensation coefficient, and the lower the generated real-time judgment threshold, so as to improve the sensitivity of capturing weak respiratory signals under the condition of high flow channel impedance.

[0084] In this embodiment, dynamic sensitivity compensation is used to overcome the technical problem that as the filter element 23 accumulates dust on its surface over time, the air path resistance increases, thereby weakening the effect of breathing airflow on motor load modulation.

[0085] Dynamic sensitivity compensation senses environmental changes by continuously monitoring the average load current of the brushless DC motor 32 during stable operation. Since increased flow channel impedance leads to a decrease in the working flow rate of the centrifugal impeller 33 and a drop in aerodynamic load torque, resulting in a decrease in operating current, the difference between the current average load current and the factory-set steady-state reference current objectively quantifies the degree of flow channel blockage. To prevent errors in the steady-state reference current recording caused by starting the system when the filter element is severely clogged—that is, misidentifying a high-impedance state as the initial low-impedance reference—the microcontroller unit 411 stores a factory-set cleanliness reference value in its non-volatile memory.

[0086] The microcontroller unit 411 internally maintains a correlation table between impedance and compensation coefficient. The calibration logic of this correlation table is as follows: During the laboratory calibration phase, standard damping meshes of different mesh sizes are used to progressively block the air inlet to physically simulate different levels of filter dust accumulation impedance; under each impedance level, the measurement system can effectively identify the minimum current fluctuation amplitude required for a standard breathing action; the ratio of this minimum current fluctuation amplitude to the standard amplitude under clean filter conditions is calculated, and this ratio is directly defined as the signal attenuation compensation coefficient. This coefficient is then anchored and stored one-to-one with the current average load current difference, thereby completing the establishment of the lookup table database.

[0087] In this logic, the calculated current difference is used as a lookup table index. When the difference increases, it indicates that the filter is severely clogged, and the flow change caused by the breathing action has been significantly attenuated by the time it reaches the centrifugal impeller 33. The resulting current fluctuation amplitude is lower than the preset conventional fluctuation judgment threshold. At this time, the dynamic sensitivity compensation logic will select a smaller signal attenuation compensation coefficient.

[0088] This coefficient is used to correct the standard current fluctuation threshold, i.e., the threshold for determining breathing switching. The specific calculation logic follows the formula:

[0089]

[0090] in, To determine the threshold in real time, The standard current fluctuation threshold, This is the signal attenuation compensation coefficient; the smaller the coefficient, the lower the final real-time judgment threshold. This means that under high-impedance conditions with a clogged filter, the system automatically increases its sensitivity to minute current fluctuations, triggering a breathing state switch as soon as a slight change in slope is detected. This mechanism ensures that the mask maintains consistent and sensitive breathing tracking performance throughout the entire lifespan of the filter, from when it is brand new until it reaches its maximum dust holding capacity, avoiding tracking lag or failure caused by signal attenuation.

[0091] The system operation also includes a filter clogging compensation step:

[0092] Calculate the average current value over one respiratory cycle;

[0093] When the average current value shows a slow downward trend and it is confirmed by monitoring the breathing switching frequency that the wearer is not in a state of accelerated breathing rate, it is determined that the filter element 23 in the filter assembly 20 is dusty.

[0094] The pulse width modulation reference duty cycle is automatically increased to improve the overall speed range of the centrifugal impeller 33, thereby overcoming the air intake resistance caused by dust accumulation.

[0095] The filter clogging compensation step in this embodiment aims to solve the problem that the overall air intake volume decreases due to dust accumulation on the filter element, making it unable to meet basic breathing needs.

[0096] The filter clogging compensation process runs continuously in the background. The microcontroller unit 411 calculates the average motor current value within a complete breathing cycle, including inhalation and exhalation. Since the current fluctuation caused by breathing is periodic, while the increase in resistance caused by dust accumulation is a long-term cumulative unidirectional trend, the system separates these two signals by comparing the average current data of multiple consecutive breathing cycles.

[0097] When the average current value shows a slow upward trend over a long period, and it is confirmed by monitoring the breathing switching frequency that the wearer is not in a state of increased breathing rate caused by strenuous exercise, the filter clogging compensation step determines that the current drop is caused by physical clogging of filter 23.

[0098] Upon confirmation of blockage, the mainboard 41 automatically adjusts the motor's basic drive parameters. The system increases or improves the pulse width modulation (PWM) reference duty cycle supplied to the brushless DC motor 32, thereby increasing the overall speed range of the centrifugal impeller 33. This adjustment allows the motor to operate at higher speeds during all stages of inhalation and exhalation, generating higher static pressure sufficient to overcome the additional intake resistance caused by dust accumulation. This ensures that the actual airflow through the filter element remains within a safe range for effective protection, preventing insufficient air supply due to filter element aging.

[0099] Because increasing the base voltage directly increases the electromagnetic torque of the motor, thereby driving the centrifugal impeller 33 to operate at a higher static pressure point, it can offset the additional pressure drop caused by dust accumulation in the filter element and ensure a constant output flow.

[0100] In step S1, the physical isolation between the positive pressure air supply chamber 15 and the negative pressure air intake chamber 14 is achieved in the following way:

[0101] An upwardly protruding annular partition wall 13 is provided on the upper surface of the air inlet base 12;

[0102] When the outer cover 11 is fastened, its inner side is tightly pressed against the sealing rib 131 at the top of the annular partition wall 13.

[0103] A negative pressure air intake chamber 14 is formed in the outer region of the annular partition wall 13, and a positive pressure air supply chamber 15 is formed in the inner region of the annular partition wall 13.

[0104] In this embodiment, the physical isolation between the positive pressure air supply chamber 15 and the negative pressure air intake chamber 14, through a specific mechanical structure design, ensures the uniqueness of the airflow path and the accurate transmission of pressure changes, providing a stable fluid dynamic environment for the current sensing-based control method.

[0105] The physical isolation between the positive pressure air supply chamber 15 and the negative pressure air intake chamber 14 relies on the annular partition wall 13 integrally injection molded on the air inlet base 12. This partition wall acts as a rigid boundary, dividing the internal space of the mask into two functionally distinct areas.

[0106] To achieve strict airtightness, the outer cover 11 is locked to the air inlet base 12 by multiple self-tapping screws. During the locking process, the inner surface of the outer cover 11 is pressed downward, interfering with the sealing rib position 131 preset at the top of the annular partition wall 13. This tight compression eliminates the possibility of gas leakage or crossflow between the two cavities.

[0107] Therefore, the outer region of the annular partition wall 13 is defined as the negative pressure intake chamber 14, which is specifically used to collect external air that has passed through the filter assembly 20. At this time, the airflow is in a low-pressure state before being drawn in. The inner region of the annular partition wall 13 is defined as the positive pressure air supply chamber 15, which houses the high-speed rotating centrifugal impeller 33, where the airflow is accelerated and pressurized. This clear physical isolation forces all airflow to pass through the centrifugal impeller 33 to enter the positive pressure zone from the negative pressure zone. This means that any change in the airflow state, such as pressure fluctuations caused by human breathing, will directly and completely affect the impeller load, thereby ensuring that the motor current signal can accurately and without interference reflect the breathing state.

[0108] In step S1, the filter assembly 20 includes a waterproof box base 21 connected to both sides of the air inlet base 12 by a buckle 24. The mating surface of the waterproof box base 21 and the air inlet base 12 is provided with a plastic elastomer sealing layer 22, which forms an airtight flow channel after being pressed.

[0109] The sealing layer 22 is fixed to the periphery of the sealing surface of the waterproof box base 21 through a secondary injection molding process, and its elastic deformation is sufficient to compensate for the flatness error of the injection molded part.

[0110] In this embodiment, the filter component 20 not only performs the function of filtering dust, but its connection structure is designed to ensure that the external pneumatic pressure signal can be transmitted to the internal sensor components and motor without loss.

[0111] The waterproof box base 21 in the filter assembly 20 is manufactured by injection molding. The connection interface between the base 21 and the air inlet base 12 adopts a secondary injection molding or wrapping process, integrating a layer of thermoplastic elastomer sealing wrapping layer 22.

[0112] When the waterproof box base 21 is fastened to both sides of the air inlet base 12 via the snap-fit ​​structure 24, the fastening force provided by the snap-fit ​​24 compresses the thermoplastic elastomer soft rubber layer. The soft rubber layer undergoes elastic deformation, filling any microscopic gaps that may exist between the mating surfaces of the two rigid plastic parts, forming a completely airtight airflow channel;

[0113] This airtight design is not only for waterproofing and dustproofing, but more importantly, for creating a rigid pressure transmission channel. When the wearer inhales, creating negative pressure inside the mask, this pressure drop can quickly extend to the air inlet through this airtight channel, driving external air to pass through the filter element 23 at an accelerated speed. If there is a leak at the connection, the pressure wave generated by breathing will be bypassed and depressurized by the leaking airflow, resulting in a reduced load change amplitude on the centrifugal impeller 33. Therefore, the application of the sealing coating layer 22 ensures high-fidelity transmission of breathing signals in the airway. Combined with the aforementioned sensitivity compensation algorithm, it further enhances the system's ability to capture signals from internal sensing and actuator devices.

[0114] Example 2:

[0115] Please see Figure 1-4 A smart face mask with air supply, comprising:

[0116] The main body component 10 of the mask is formed by the outer shell cover 11 and the air inlet base 12, and the interior is divided into a negative pressure air intake chamber 14 and a positive pressure air supply chamber 15 by an annular partition wall 13.

[0117] The air supply drive assembly 30 includes a brushless DC motor 32 located in the positive pressure air supply chamber 15 and a centrifugal impeller 33 fixed on the motor shaft; wherein, the brushless DC motor 32 is fixed in the positive pressure air supply chamber 15 by a motor mounting cover 31, and the motor mounting cover 31 serves to support and guide the airflow.

[0118] The filter assembly 20 is installed on both sides of the air inlet base 12 and connected to the negative pressure air intake chamber 14;

[0119] The motherboard 41 is electrically connected to the brushless DC motor 32 and the battery 42.

[0120] The air-purifying smart face mask in this embodiment integrates a mechanical flow channel structure and an embedded electronic control system, forming a complete personal protective equipment.

[0121] The main body component 10 of the mask serves as the skeleton, while the outer shell cover 11 and the air inlet base 12 are typically made of impact-resistant engineering plastics such as ABS or PC. The internal annular partition wall 13 establishes a single airflow direction, namely: external environment -> filter component 20 -> negative pressure air intake chamber 14 -> centrifugal impeller 33 -> positive pressure air supply chamber 15 -> facial space.

[0122] The air supply drive assembly 30 is the core power source of the system. A brushless DC motor 32, for example, a high-speed, low-inertia internal rotor brushless motor, is installed in a dedicated motor mounting cover 31. Its output shaft is tightly connected to the centrifugal impeller 33 via an interference fit. To ensure the physical system can respond to high-frequency breathing changes, the brushless DC motor 32 is specifically selected as a low-inertia internal rotor motor, whose mechanical response time constant is less than the sampling period of the control algorithm. Simultaneously, the blades of the centrifugal impeller 33 are designed with a backward-curved shape. This aerodynamic configuration ensures a monotonically linear relationship between aerodynamic load torque and speed within the operating flow range, avoiding current signal distortion caused by nonlinear aerodynamic characteristics. The backward-curved blade design of the centrifugal impeller 33 achieves a smoother aerodynamic characteristic curve, facilitating pressure estimation by the algorithm.

[0123] The motherboard 41 serves as the control center, integrating a microcontroller (MCU, such as the STM32 series), a motor drive circuit (MOSFET bridge), and a current sampling circuit; the battery 42 (such as a lithium polymer battery pack) provides power to the system. The motherboard 41 contains firmware programs that execute the aforementioned breathing follow-up control method.

[0124] In real-world scenarios, the motherboard 41 not only drives the motor to deliver air, but also reuses the motor itself as a highly sensitive breathing sensor. By collecting the current signal on the motor windings, the motherboard 41 can calculate the wearer's breathing phase in real time and dynamically adjust the motor speed according to a preset pressurization or depressurization strategy. This high degree of hardware and software synergy enables the air-blowing smart mask to achieve millisecond-level breathing response without the need for external, fragile sensors, ensuring long-term reliability and wearing comfort under harsh conditions such as dust and humidity.

[0125] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A breathing-following control method for an air-supply smart face mask, characterized in that, include: S1. A smart mask with air supply is provided. The smart mask with air supply includes a mask body assembly (10) consisting of a negative pressure air intake chamber (14) and a positive pressure air supply chamber (15) formed by the outer shell cover (11) and the air inlet base (12) forming a physically isolated negative pressure air intake chamber (14), a brushless DC motor (32) located in the positive pressure air supply chamber (15), a centrifugal impeller (33), and a filter assembly (20) connected to the negative pressure air intake chamber (14). The filter assembly (20) is provided with a filter element (23) connected to the filter assembly (20) of the negative pressure air intake chamber (14). S2. Under steady-state flow field, the brushless DC motor (32) is controlled by pulse width modulation drive signal to drive the centrifugal impeller (33) to rotate with a constant duty cycle, and the average current value under steady state is recorded as steady-state reference current. S3. After starting operation, the real-time operating current and commutation frequency of the brushless DC motor (32) are collected at high frequency. A time window queue for real-time operating current is established for data storage. The slope of the straight line fitting the operating current data with time in the queue is calculated. The commutation frequency is then used to obtain the current motor speed. S4. Perform dynamic sensitivity compensation: Calculate the difference between the steady-state reference current and the average load current under the current stable operating state, look up the preset impedance and compensation coefficient association table based on the difference, obtain the corresponding signal attenuation compensation coefficient, use the coefficient to correct the preset standard current fluctuation threshold, and generate a real-time judgment threshold. S5. Adjust the rotation speed according to the changing trend, slope direction and real-time judgment threshold of the real-time working current: When the real-time working current shows a continuous upward trend, the slope is positive and the fluctuation amplitude exceeds the real-time judgment threshold, it is judged as the inhalation start segment and the pressure boosting strategy is executed; when the real-time working current shows a continuous downward trend, the slope is negative and the fluctuation amplitude exceeds the real-time judgment threshold, it is judged as the exhalation start segment and the pressure depressurization strategy is executed.

2. The breathing tracking control method for an air-supply smart face mask according to claim 1, characterized in that, In step S5, the steps for implementing the boost strategy include: Call the pre-stored pressure-flow-current-speed multidimensional characteristic mapping data model; The current motor speed and operating current are input into the multidimensional characteristic mapping data model, and the real-time air pressure inside the mask is estimated through multidimensional interpolation calculation. The deviation between the real-time air pressure value and the preset target micro-positive pressure value is calculated using a proportional-integral-derivative control algorithm. Adjust the duty cycle of the pulse width modulation drive signal according to the deviation to increase the speed of the brushless DC motor (32) until the real-time air pressure value reaches the target micro-positive pressure value.

3. The breathing tracking control method for an air-supply smart face mask according to claim 1, characterized in that, In step S5, the steps for implementing the buck strategy include: Reduce the duty cycle of the pulse width modulation drive signal and control the brushless DC motor (32) to decelerate to the standby speed that maintains the minimum ventilation volume, so as to reduce the resistance between the exhaled airflow and the supplied airflow.

4. The breathing tracking control method for a smart air-supply face mask according to claim 1, characterized in that, In step S4, dynamic sensitivity compensation follows the following logic: The difference is used to characterize the degree of blockage resistance in the flow channel; The larger the difference, the smaller the corresponding signal attenuation compensation coefficient, and the lower the generated real-time judgment threshold, so as to improve the sensitivity of capturing weak respiratory signals under the condition of high flow channel impedance.

5. The breathing tracking control method for a smart air-supply face mask according to claim 1, characterized in that, The system operation also includes a filter clogging compensation step: Calculate the average current value over one respiratory cycle; When the average current value shows a slow downward trend and it is confirmed by monitoring the breathing switching frequency that the wearer is not in a state of accelerated breathing rate, it is determined that the filter element (23) in the filter assembly (20) is dusty; The pulse width modulation reference duty cycle is automatically increased to improve the overall speed range of the centrifugal impeller (33) in order to overcome the air intake resistance caused by dust accumulation.

6. The breathing tracking control method for an air-supply smart face mask according to claim 1, characterized in that, In step S1, the physical isolation between the positive pressure air supply chamber (15) and the negative pressure air intake chamber (14) is achieved in the following way: An upward-protruding annular partition wall (13) is provided on the upper surface of the air inlet base (12). When the outer cover (11) is fastened, its inner side is tightly pressed against the sealing rib (131) at the top of the annular partition wall (13); A negative pressure air intake chamber (14) is formed in the outer region of the annular partition wall (13), and a positive pressure air supply chamber (15) is formed in the inner region of the annular partition wall (13).

7. The breathing tracking control method for an air-supply smart face mask according to claim 1, characterized in that, In step S1, the filter assembly (20) includes a waterproof box base (21) connected to both sides of the air inlet base (12) by a buckle (24). The mating surface of the waterproof box base (21) and the air inlet base (12) is provided with a plastic elastomer sealing layer (22), which forms an airtight flow channel after being pressed.

8. A smart face mask with air supply, characterized in that, include: The main body assembly of the mask (10) is formed by the outer shell cover (11) and the air inlet base (12), and the interior is divided into a negative pressure air intake chamber (14) and a positive pressure air supply chamber (15) by an annular partition wall (13). The air supply drive assembly (30) includes a brushless DC motor (32) located in the positive pressure air supply chamber (15) and a centrifugal impeller (33) fixed on the motor shaft. The filter assembly (20) is installed on both sides of the air inlet base (12) and connected to the negative pressure suction chamber (14). A motherboard (41) is electrically connected to a brushless DC motor (32) and a battery (42), wherein the battery (42) is configured to provide power to the battery (42); the motherboard (41) is configured to perform a breathing follow-up control method for an air-purifying smart mask as described in any one of claims 1-7.

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