Hot-wire flow sensor and particulate matter detection method thereof

Abstract

A hot wire flow sensor and a particulate matter detection method thereof are disclosed. The hot wire flow sensor includes an inlet and an outlet. The hot wire flow sensor further includes an ambient measurement unit disposed at the inlet side or the outlet side and measuring particulate matter data of a gas in the hot wire flow sensor; a particulate matter concentration calculation unit sampling the particulate matter data of the gas measured by the ambient measurement unit and obtaining particulate matter concentration data of the gas based on the sampled data; a comparison unit comparing the particulate matter concentration data with a predetermined threshold and generating a comparison result; and a notification unit receiving the comparison result generated by the comparison unit and generating notification information according to the comparison result.

Description

Technical Field

[0001] This application relates to the field of medical devices, and more particularly to a flow sensor and a ventilator and anesthesia machine having the flow sensor. Background Technology

[0002] With the development of modern medicine, ventilators, as an effective means of artificially replacing spontaneous ventilation, are widely used to treat sleep apnea or other respiratory disorders. The flow sensor, as a crucial component in the ventilator's airway structure, not only plays a decisive role in the ventilator's alarm function but also monitors the patient's inspiratory and respiratory flow rate and pressure in real time, feeding this information back to the ventilator's control system to assist in more accurate control of parameters such as patient flow rate, pressure, and tidal volume.

[0003] Flow sensors are precision electronic detection components and are core parts for monitoring gas volume and flow rate during ventilator use. Currently, due to differences in ventilator manufacturers, the structure and operating principles of ventilators vary, resulting in the use of different flow sensors. Based on their working principles, they can be broadly categorized as follows: hot-wire flow sensors, hot-film flow sensors, ultrasonic flow sensors, and pressure-measuring flow sensors.

[0004] The basic principle of a hot-wire flow sensor is to place a thin metal wire (whose resistance varies at different temperatures) in the gas stream being measured. An electric current heats the wire, raising its temperature above the fluid's temperature. When the gas flows over the hot wire, it carries away some of the wire's heat, causing the wire's temperature to drop. The amount of heat dissipated by the wire in the gas is related to the flow rate. This heat dissipation causes a change in the wire's temperature, which in turn causes a change in resistance. The flow rate signal is then converted into an electrical signal. After appropriate signal transformation and processing, the gas flow rate is measured. The hot wire, placed in the measurement channel, acts as one arm of a Wheatstone bridge. The hot wire placed in the measurement channel serves as one arm of a Wheatstone bridge. An operational amplifier differentially amplifies the voltage signal output from the bridge. The operational amplifier provides the bias voltage required for the transistor's operation and allows the operational amplifier's output signal to be superimposed on the transistor's bias potential, then amplified by the transistor to power the bridge. The feedback loop, consisting of the bridge circuit, operational amplifier, and transistor, ensures the hot wire operates at a constant temperature. Upon power-on, the hot wire resistor rapidly heats up, and its resistance immediately increases, quickly bringing the bridge to equilibrium. When fluid flows through the flow meter, the temperature and impedance of the hot wire change due to heat exchange, causing the bridge to become unbalanced. The fluid flow rate can then be measured based on the output feedback voltage signal. The higher the flow velocity per unit cross-sectional area, the faster the hot wire cools down. Therefore, the hot wire requires more electrical energy to maintain a stable temperature (180°C). The energy required to keep the hot wire at 180°C represents the flow rate of the airflow passing through the sensor and cooling the hot wire.

[0005] Hot-wire flow sensors offer significant advantages in terms of high precision, making them widely used as precision electronic detection components in medical devices such as ventilators and anesthesia machines. However, because the guide wire in a hot-wire flow sensor is extremely thin, if patient secretions or condensation adhere to the platinum wire of the flow sensor, especially residual medication after nebulization therapy, it can cause the flow sensor to malfunction. In severe cases, it can even cause the platinum wire to melt and the flow sensor to be destroyed. Summary of the Invention

[0006] In view of the above, a hot-wire flow sensor with an environmental sensor and its particulate matter detection method are proposed. This sensor can detect the cleanliness quality of the gas in the breathing circuit. For example, a particulate sensor such as PM2.5 can be used to detect the cleanliness quality of the gas in the breathing circuit of a ventilator or anesthesia machine. When the cleanliness deteriorates, an alert can be issued to notify the user to clean the breathing circuit, thereby helping to improve the durability of the sensor.

[0007] According to one aspect of the present invention, a hot-wire flow sensor is provided, the hot-wire flow sensor including an air inlet and an air outlet, characterized in that the hot-wire flow sensor further includes: an environmental measurement unit disposed on the air inlet side or the air outlet side, and the environmental measurement unit measuring particulate matter data of the gas in the hot-wire flow sensor; a particulate matter concentration calculation unit sampling the particulate matter data of the gas measured by the environmental measurement unit, and obtaining particulate matter concentration data of the gas based on the sampled data; a comparison unit comparing the particulate matter concentration data with a predetermined threshold and generating a comparison result; and a notification unit receiving the comparison result generated by the comparison unit and generating notification information according to the comparison result.

[0008] Preferably, when the comparison result indicates that the particulate matter concentration data is greater than a predetermined threshold, the notification unit generates a prompt message to clean the hot wire flow sensor.

[0009] Preferably, the hot-wire flow sensor further includes: a start-up unit that starts the environmental measurement unit according to a user's operation command or according to a predetermined start-up cycle.

[0010] Preferably, the hot-wire flow sensor further includes: a display unit that displays at least one of the following: particulate matter data of the gas in the hot-wire flow sensor measured by the environmental measurement unit; particulate matter concentration data of the gas obtained by the particulate matter concentration calculation unit; and the comparison result generated by the comparison unit.

[0011] Preferably, the environmental measurement unit includes a laser module and a photodiode, the laser module and the photodiode being disposed opposite to each other, and the laser module emitting a laser beam that irradiates particulate matter in the gas to generate scattered light, which is received by the photodiode.

[0012] Preferably, the laser module is a red laser module that emits a wavelength of 650nm.

[0013] Preferably, the hot-wire flow sensor further includes a filter unit disposed on the air inlet side, and the filter unit filters the gas flowing into the hot-wire flow sensor.

[0014] Preferably, the filter unit includes a filter screen and / or filter cotton, and the filter unit is detachably disposed on the air inlet side.

[0015] Preferably, a pull strap is installed on one side of the filter unit, the pull strap being used to remove the filter unit from inside the hot wire flow sensor.

[0016] According to one aspect of the present invention, a method for particulate matter detection for a hot-wire flow sensor is provided, the hot-wire flow sensor including an inlet and an outlet, characterized in that the method for particulate matter detection for the hot-wire flow sensor includes: an environmental measurement step, measuring particulate matter data of a gas in the hot-wire flow sensor; a particulate matter concentration calculation step, sampling the particulate matter data of the gas measured in the environmental measurement step, and obtaining particulate matter concentration data of the gas based on the sampled data; a comparison step, comparing the particulate matter concentration data with a predetermined threshold and generating a comparison result; and a notification step, receiving the comparison result generated by the comparison step, and generating notification information based on the comparison result.

[0017] Preferably, in the notification step, when the comparison result indicates that the particulate matter concentration data is greater than a predetermined threshold, a prompt message for cleaning the hot wire flow sensor is generated.

[0018] Preferably, before the environmental measurement step, the method further includes a startup step, which starts the environmental measurement step according to the user's operation instructions or according to a predetermined startup cycle.

[0019] Preferably, after the notification step, the method further includes a display step, displaying at least one of the following: particulate matter data of the gas in the hot-wire flow sensor measured by the environmental measurement step; particulate matter concentration data of the gas obtained by the particulate matter concentration calculation step; and the comparison result generated by the comparison step.

[0020] As can be seen from the above scheme, by setting up environmental sensors, the cleanliness quality of the gas in the breathing circuit can be sensed. For example, a particulate sensor such as PM2.5 can be used to sense the cleanliness quality of the gas in the breathing circuit of a ventilator or anesthesia machine. When the cleanliness deteriorates, an alert can be issued to notify the user to clean the breathing circuit, thereby helping to improve the durability of the sensor. Attached Figure Description

[0021] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which will make the above and other features and advantages of the present invention more apparent to those skilled in the art. In the drawings:

[0022] Figure 1A schematic diagram of a hot-wire flow sensor according to an embodiment of the present invention is shown;

[0023] Figure 2 A circuit diagram is shown below, illustrating the use of an infrared LED particulate matter concentration sensor as a hot-wire flow sensor with an environmental sensor, according to an embodiment of the present invention.

[0024] Figure 3 A functional block diagram of a hot-wire flow sensor according to an embodiment of the present invention is shown; and

[0025] Figure 4 A flowchart of a particulate matter detection method using a hot-wire flow sensor according to an embodiment of the present invention is shown. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the following embodiments are provided to further illustrate the present invention in detail.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0030] Figure 1 A schematic diagram of a hot-wire flow sensor according to an embodiment of the present invention is shown. Figure 1The upper part of the diagram shows a side view of the hot-wire flow sensor. As shown, the hot-wire flow sensor 10 includes an inlet 102, an outlet 104, and a thermistor platinum wire 106. When gas flows from the inlet 102 to the outlet 104 in the direction of the arrow, it carries away heat as it passes over the surface of the thermistor platinum wire 106. A temperature sensor in the hot-wire control device continuously measures the temperature of the hot wire and then measures the energy required to heat the wire and maintain it at a fixed temperature. The gas flow rate is measured by measuring the amount of electricity required for heating. The resistance of the thermistor platinum wire 106 changes with the gas flow rate, causing the circuit to lose its original balance and generating an unbalanced current signal. The magnitude of this signal corresponds to the gas flow rate, thus allowing the gas flow rate to be measured based on the gas's thermal conductivity. In this application, the hot-wire flow sensor also includes an environmental measurement unit 108, although... Figure 1 The environmental measurement unit 108 is positioned on the inlet side 102, but it can also be positioned on the outlet side 104. The installation position of the environmental measurement unit 108 can be set as needed, provided it can sense the cleanliness quality of the gas in the breathing circuit. During the use of the hot-wire flow sensor, patient secretions, condensate, and other particulate matter can adhere to the platinum wire of the flow sensor along with the gas, causing the flow sensor to malfunction and become unusable. In severe cases, it can even cause the platinum wire to melt and the flow sensor to be damaged. In this application, to reduce the cost of replacement due to damage, an environmental measurement unit 108 can be provided to facilitate sensing the cleanliness quality of the gas in the breathing circuit of the ventilator or anesthesia machine. When the cleanliness deteriorates, a prompt can be issued to notify the user to clean the breathing circuit, thereby helping to improve the durability of the sensor. Furthermore, although not shown in the figure, the hot-wire flow sensor may further include a filter unit, positioned on the inlet side, which filters the gas flowing into the hot-wire flow sensor. For example, the filter unit includes a filter screen and / or filter cotton, and is detachably mounted on the inlet side. For example, a pull strap can be installed on one end of the side of the filter unit to remove it from inside the hot-wire flow sensor when cleaning or replacement is required. The cross-section of the filter unit matches the cross-section of the inlet, allowing the filter unit to fit snugly against the inner wall of the inlet. Figure 1 The lower part of the diagram shows an enlarged view of the environmental measurement unit 108. The environmental measurement unit 108 includes, for example, an infrared emitting sensor 108-2 and an infrared receiving sensor 108-4, which are arranged opposite to each other. The infrared emitting sensor 108-2 emits infrared light, which irradiates particulate matter in the gas, causing scattered light due to the particulate matter. The infrared receiving sensor 108-4 receives the scattered light. The following references... Figure 2This section describes in detail the working principle of an infrared LED particulate matter concentration sensor.

[0031] Figure 2 A circuit diagram of an infrared LED particulate matter concentration sensor as a hot-wire flow sensor with an environmental sensor, according to an embodiment of the present invention, is shown. The particulate matter sensor utilizes the principle of light scattering and photoelectric conversion technology to measure and detect particulate matter. Its main function is to sense the cleanliness of the gas in the breathing circuit of a ventilator or anesthesia machine, and to issue a prompt to notify the user to clean the breathing circuit when the cleanliness deteriorates based on the sensor's sensing signal. In the operation of laser particulate matter sensing, a laser beam emitted by the transmitter travels along the optical path to the receiver. During this process, the light is attenuated by absorption and scattering from the particles contained in the gas. The receiver determines the opacity of the gas based on the ratio of the received light intensity to the incident light intensity, thereby reflecting the concentration of particulate matter in the gas. Specifically, as... Figure 2 As shown, the infrared emitting LED light source 202 outputs a high-level signal when particles pass through the airflow sensor. Because the particle signal scattered by the infrared LED light is weak, it only responds to large particles larger than 1µm. Therefore, the structure and circuit of a dust sensor using the infrared principle are relatively simple. Figure 2 As shown, when particulate matter concentration needs to be measured, the infrared emitting LED driver circuit 204 is controlled to enter the working state by the corresponding output IO on the microcontroller (MCU) 206 of the ventilator / anesthesia machine. The infrared emitting LED light source 202 emits infrared light. At this time, when particles 214 pass through the flow sensor, the infrared receiving sensor 210 outputs high and low level signal changes. This level signal is amplified by the amplifier circuit 208. The amplified level signal is sampled by the A / D sampling unit of the microcontroller (MCU) 206 to obtain particulate matter passing data. The microcontroller (MCU) 206 then calculates the data to obtain particulate matter concentration data. When the calculated particulate matter concentration exceeds a certain preset limit, the ventilator / anesthesia machine will display the corresponding particulate matter concentration exceeding the limit alarm indication inside the flow sensor through the human-machine interface display 212, prompting the user to clean the flow sensor pipeline in time.

[0032] Figure 3 A functional block diagram of a hot-wire flow sensor according to an embodiment of the present invention is shown. Figure 3 Examples are shown Figure 2 The diagram shown illustrates a functional block diagram of a hot-wire flow sensor equipped with an infrared LED particulate matter concentration sensor, used as an environmental sensor. Figure 3As shown, the hot-wire flow sensor includes: a start-up unit 302, which starts the environmental measurement unit 304 according to a user's operation command or a predetermined start-up cycle (e.g., every day, every week, or every month); the environmental measurement unit 304, located on the inlet side or the outlet side, measures particulate matter data of the gas in the hot-wire flow sensor; a particulate matter concentration calculation unit 306, which samples the particulate matter data of the gas measured by the environmental measurement unit 304 and obtains particulate matter concentration data of the gas based on the sampled data; and a comparison unit 308, which compares the particulate matter concentration data with a predetermined... The comparison is performed using a predetermined threshold, and a comparison result is generated. The notification unit 310 receives the comparison result generated by the comparison unit 308, and when the comparison result shows that the particulate matter concentration data is greater than the predetermined threshold, the notification unit 310 generates a prompt message for cleaning the hot wire flow sensor (e.g., by auditory, visual, or tactile means). The display unit 312 displays at least one of the following: particulate matter data of the gas in the hot wire flow sensor measured by the environmental measurement unit 304, particulate matter concentration data of the gas obtained by the particulate matter concentration calculation unit 306, and the comparison result generated by the comparison unit 308.

[0033] Figure 4 A flowchart illustrating a particulate matter detection method using a hot-wire flow sensor according to an embodiment of the present invention is shown. Figure 4 As shown, the particulate matter detection method for a hot-wire flow sensor includes the following steps: Initiation step 402, initiating environmental measurement according to user operation instructions or a predetermined initiation cycle (e.g., every day, every week, or every month); Environmental measurement step 404, measuring particulate matter data of the gas in the hot-wire flow sensor; Particulate matter concentration calculation step 406, sampling the particulate matter data of the gas measured in environmental measurement step 404, and obtaining particulate matter concentration data of the gas based on the sampled data; Comparison step 408, comparing the particulate matter concentration data with a predetermined threshold. The comparison result is generated; step 410 is notified to receive the comparison result generated in comparison step 408, and when the comparison result shows that the particulate matter concentration data is greater than a predetermined threshold, step 410 is notified to generate a prompt message for cleaning the hot wire flow sensor (e.g., by auditory, visual or tactile means); step 412 is displayed to display at least one of the following: particulate matter data of the gas in the hot wire flow sensor measured in environmental measurement step 404, particulate matter concentration data of the gas obtained in particulate matter concentration calculation step 406, and comparison result generated in comparison step 408.

[0034] As can be seen from the above solutions, the hot-wire flow sensor and particulate matter detection method for the hot-wire flow sensor proposed in this invention can sense the cleanliness quality of the gas in the breathing circuit by setting an environmental sensor. For example, a particulate sensor such as PM2.5 can be used to sense the cleanliness quality of the gas in the breathing circuit of a ventilator or anesthesia machine. When the cleanliness deteriorates, a prompt can be issued to notify the user to clean the breathing circuit, thereby helping to improve the durability of the sensor.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hot-wire flow sensor, the hot-wire flow sensor comprising an air inlet and an air outlet, characterized in that, The hot-wire flow sensor further includes: An environmental measurement unit is disposed on the air inlet side or the air outlet side, and the environmental measurement unit measures the particulate matter data of the gas in the hot wire flow sensor; The particulate matter concentration calculation unit samples the particulate matter data of the gas measured by the environmental measurement unit and obtains the particulate matter concentration data of the gas based on the sampled data. The comparison unit compares the particulate matter concentration data with a predetermined threshold and generates a comparison result; and The notification unit receives the comparison result generated by the comparison unit, and when the comparison result shows that the particulate matter concentration data is greater than a predetermined threshold, the notification unit generates a prompt message to clean the hot wire flow sensor.

2. The hot-wire flow sensor according to claim 1, characterized in that, The hot-wire flow sensor further includes a start-up unit that starts the environmental measurement unit according to a user's operation command or a predetermined start-up cycle.

3. The hot-wire flow sensor according to claim 1, characterized in that, The hot-wire flow sensor further includes a display unit that displays at least one of the following: particulate matter data of the gas in the hot-wire flow sensor measured by the environmental measurement unit; particulate matter concentration data of the gas obtained by the particulate matter concentration calculation unit; and the comparison result generated by the comparison unit.

4. The hot-wire flow sensor according to claim 1, characterized in that, The environmental measurement unit includes a light emitting module and a light receiving module, which are arranged opposite to each other. The light emitting module emits light, which irradiates particulate matter in the gas to generate scattered light, and the light receiving module receives the scattered light.

5. The hot-wire flow sensor according to claim 4, characterized in that, The light emitting module is an infrared emitting LED, and the light receiving module is an infrared receiving sensor.

6. The hot-wire flow sensor according to claim 4, characterized in that, The optical emitting module is a laser emitter, and the optical receiving module is a laser receiver.

7. The hot-wire flow sensor according to claim 6, characterized in that, The laser emitter is an infrared laser that emits a wavelength of 650nm.

8. The hot-wire flow sensor according to claim 1, characterized in that, The hot-wire flow sensor further includes a filter unit disposed on the air inlet side, and the filter unit filters the gas flowing into the hot-wire flow sensor.

9. The hot-wire flow sensor according to claim 8, characterized in that, The filter unit includes a filter screen and / or filter cotton, and the filter unit is detachably disposed on the air inlet side.

10. The hot-wire flow sensor according to claim 9, characterized in that, A pull strap is installed on one side of the filter unit, which is used to remove the filter unit from inside the hot wire flow sensor.

11. A method for particulate matter detection using a hot-wire flow sensor, the hot-wire flow sensor comprising an inlet and an outlet, characterized in that, The particulate matter detection method for a hot-wire flow sensor includes: The environmental measurement step involves measuring particulate matter data of the gas in the hot-wire flow sensor. The particulate matter concentration calculation step involves sampling the particulate matter data of the gas measured in the environmental measurement step, and obtaining the particulate matter concentration data of the gas based on the sampled data. The comparison step involves comparing the particulate matter concentration data with a predetermined threshold and generating a comparison result; and The notification step receives the comparison result generated by the comparison step, and when the comparison result shows that the particulate matter concentration data is greater than a predetermined threshold, generates a prompt message to clean the hot wire flow sensor.

12. The particulate matter detection method for a hot-wire flow sensor according to claim 11, characterized in that, Prior to the environmental measurement step, a startup step is also included, which initiates the environmental measurement step according to the user's operation instructions or according to a predetermined startup cycle.

13. The particulate matter detection method for a hot-wire flow sensor according to claim 11, characterized in that, Following the notification step, a display step is also included, displaying at least one of the following: particulate matter data of the gas in the hot-wire flow sensor measured by the environmental measurement step; particulate matter concentration data of the gas obtained by the particulate matter concentration calculation step; and the comparison result generated by the comparison step.

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