Breathing aid

Abstract

To provide a respiratory assistance apparatus having an improved gas composition sensing capability.SOLUTION: A respiratory assistance apparatus has a gases inlet configured to receive a supply of gases; a blower unit configured to generate a pressurised gases stream from the supply of gases; a humidification unit configured to heat and humidify the pressurised gases stream; and a gases outlet for a heated and humidified gases stream. A flow path for the gases stream extends through a respiratory device from the gases inlet through the blower unit and the humidification unit to the gases outlet. A sensor assembly is provided in the flow path before the humidification unit. The sensor assembly has an ultrasound gas composition sensor system for sensing one or more gas concentrations within the gases stream.SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] The present invention relates to a respiratory assistance device that provides a user with a warmed and humidified gas flow for therapeutic purposes. Although not exclusive, in particular, the respiratory assistance device can provide respiratory assistance to patients or users who require a supply of warmed and humidified gas for respiratory treatments such as respiratory humidification therapy, high-flow oxygen therapy, CPAP therapy, Bi-PAP therapy, and airway positive pressure (PAP) therapy including OPAP therapy, usually for the treatment of diseases such as obstructive sleep apnea (OSA), snoring, and chronic obstructive pulmonary disease (COPD).

Background Art

[0002] Respiratory assistance devices or systems that provide a flow of humidified and warmed gas to a patient for therapeutic purposes are well known in the art. Systems that provide this type of treatment (e.g., respiratory humidification) typically have a structure that sends gas from a gas source to a humidifier chamber, such as a blower (also known as a compressor, ventilator unit, fan unit, flow generator, or pressure generator). The gas becomes saturated with water vapor as it passes over the water in the humidifier chamber or through the warmed and humidified air. The warmed and humidified gas is then sent from the humidifier chamber to a downstream user or patient via a gas conduit and a user interface.

[0003] In one form, such a respiratory assistance system can be a modular system that includes a separate (modular) humidifier unit and a blower unit. The modules are connected in series via connecting conduits to pass gas from the blower unit to the humidifier unit. For example, FIG.1 shows a schematic view of a user 1 receiving warmed and humidified air from a modular respiratory assistance system. Pressurized air is provided from a ventilator unit or blower unit 2a to a humidifier chamber 4a via a connector conduit 10. The humidified, warmed, and pressurized air flow exits the humidifier chamber 4a via a user conduit 3 and is provided to the patient or user 1 via a user interface 5.

[0004] In an alternative configuration, the respiratory support system can be an integrated system in which the blower unit and humidifier unit are contained within the same housing. A typical integrated system consists of a main blower unit or ventilator unit that provides a pressurized gas flow and a humidifier unit that is fitted into the blower unit or otherwise securely connected. For example, the humidifier unit is fitted into the blower unit by a slide-in or push-in connection, thereby ensuring that the humidifier unit is securely connected to the main blower unit and held firmly in place on the main blower unit. Figure 2 shows a schematic diagram of user 1 receiving heated and humidified air from an integrated respiratory support system 6. The system operates similarly to the modular system shown in Figure 1, but the humidifier chamber 4b is integrated with the blower unit to form the integrated system 6.

[0005] The user interface 5 shown in Figures 1 and 2 is a nasal mask that covers the nose of user 1. However, it should be noted that in these types of systems, a mask that covers both the mouth and nose, a full-face mask, a nasal cannula, or any other suitable user interface may be used as a substitute for the nasal mask shown. It is also possible to use a mouth-only interface or mouth mask. Furthermore, the patient or user end of the conduit may be connected to a tracheostomy connector or endotracheal intubation.

[0006] U.S. Patent No. 7,111,624 includes a detailed description of an integrated system. For use, a “slide-on” water chamber is connected to the blower unit. One variation of this design is a slide-on or clip-on design in which, for use, the chamber is enclosed within a portion of the integrated unit. An example of this type of design is shown in International Publication No. 2004 / 112873, which describes a blower or flow generator 50 and an associated humidifier 150.

[0007] For these integrated systems, the most common operating mode is as follows: Air is drawn by a blower through an inlet into a case that encloses at least the blower portion of the system. The blower pressurizes the airflow from the flow generator inlet and passes it to the humidifier chamber. The airflow is heated and humidified in the humidifier chamber and exits the humidifier chamber through the inlet. A flexible hose or conduit is connected directly or indirectly to the humidifier outlet, and the heated and humidified gas is passed to the user through the conduit. This is schematically illustrated in Figure 2.

[0008] In both modular and integrated systems, the gas supplied by the blower unit is generally sourced from ambient air. However, some forms of these systems can be configured to allow the supplemental gas to be mixed with atmospheric air for specific treatments. In such systems, the gas conduit supplying the supplemental gas is typically connected directly to the humidifier chamber or somewhere else on the high-pressure (outlet) side of the blower unit, or alternatively, to the inlet side of the blower unit, as described in International Publication No. 2007 / 004898. This type of respiratory support system is generally used when the patient or user requires oxygen therapy and oxygen is supplied from a central gas source. The oxygen from the gas source is mixed with atmospheric air to increase the oxygen concentration before being delivered to the patient. Such systems make it possible to combine oxygen therapy with high-flow humidification therapy for the treatment of diseases such as COPD. In such treatments, it is important that the oxygen concentration delivered to the patient is known and controlled. Currently, the oxygen concentration delivered to the patient is typically calculated manually or estimated based on a printed reference table that presents various oxygen concentrations pre-calculated based on the various oxygen flow rates supplied from the central gas source and the various flow rates generated by the blower unit.

[0009] Where references are made in this specification to patent specifications, other external documents, or other sources, these are generally intended to provide background for considering the features of the present invention. Unless otherwise indicated, references to such external documents should not be construed as an admission that such documents or sources constitute prior art or part of the general knowledge in the art in any jurisdiction. [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide a respiratory support device with improved gas composition detection capabilities, or at least to provide a useful alternative for the public. [Means for solving the problem]

[0011] In a first aspect, the essence of the present invention is, in a broad sense, a respiratory assistance device configured to provide a heated and humidified gas flow, comprising: a gas inlet configured to receive a gas supply; a blower unit configured to generate a pressurized gas flow from the gas supply; a humidifier unit configured to heat and humidify the pressurized gas flow; a gas outlet for the heated and humidified gas flow; a flow path for the gas flow passing through the respiratory device from the gas inlet through the blower unit and the humidifier unit to the gas outlet; and a sensor assembly provided in the flow path in front of the humidifier unit, comprising an ultrasonic gas composition sensor system for detecting one or more gas concentrations in the gas flow.

[0012] Preferably, the ultrasonic gas composition sensor system may comprise a transmitter-receiver pair, the transmitter-receiver pair may be operable to transmit cross-flow acoustic pulses from the transmitter to the receiver through the gas flow to detect the speed of sound in the gas flow near the sensor assembly.

[0013] In one embodiment, the transmitter-receiver pair may be arranged such that the acoustic pulses move in a cross-flow direction, which is substantially perpendicular to the direction of gas flow.

[0014] In another configuration, the transmitter-receiver pair may be arranged such that the acoustic pulses travel through the gas flow in a crossflow that is inclined with respect to the direction of gas flow but is not orthogonal.

[0015] In one configuration, a transmitter-receiver pair comprising a transducer configured as a transmitter and a transducer configured as a receiver can transmit unidirectional acoustic pulses.

[0016] In another configuration, a transmitter-receiver pair may comprise a pair of transmitter-receiver transducers configured to transmit bidirectional acoustic pulses.

[0017] In one embodiment, the transmitter and receiver may be aligned with respect to the direction of gas flow and may face each other across the flow path.

[0018] In another configuration, the transmitter and receiver may be displaced from each other in the direction of the gas flow.

[0019] Preferably, the acoustic pulse may have a direct beampath between the transmitter and receiver. Alternatively, the acoustic pulse may have an indirect beampath between the transmitter and receiver, involving one or more reflections.

[0020] In another configuration, the pair of transmitter and receiver transducers may take the form of a single transmitter-receiver configured to transmit cross-flow acoustic pulses and receive echo return pulses.

[0021] In another form, the ultrasonic gas composition sensor system may include a pair of a transmitter transducer and a receiver transducer operable to transmit an acoustic pulse along a flow through a gas flow from the transmitter to the receiver to detect the speed of sound in the gas flow near the sensor assembly.

[0022] Preferably, the respiratory assist device may further include a sensor control system operably connected to the pair of the transmitter transducer and the receiver transducer of the ultrasonic gas composition sensor system, configured to detect the speed of sound through the gas flow and operate the transducer pair to generate a speed of sound signal indicating the speed of sound.

[0023] Preferably, the sensor control system is configured to generate one or more gas concentration signals indicating the gas concentration in the gas flow based at least on a signal indicating the speed of sound through the gas flow.

[0024] In one form, the sensor assembly may further include a temperature sensor configured to measure the temperature of the gas flow near the sensor assembly and generate a representative temperature signal, and the sensor control system is configured to generate one or more gas concentration signals indicating the gas concentration in the gas flow based on the speed of sound signal and the temperature signal.

[0025] In another form, the sensor assembly may further include a humidity sensor configured to measure the humidity of the gas flow near the sensor assembly and generate a representative humidity signal, and the sensor control system is configured to generate one or more gas concentration signals indicating the gas concentration in the gas flow based on the speed of sound signal and the humidity signal. By way of example, the humidity sensor may be a relative humidity sensor or an absolute humidity sensor.

[0026] In another form, the sensor assembly may include both a temperature sensor and a humidity sensor that measure the temperature and humidity of the gas flow in the vicinity of the sensor assembly and generate respective representative temperature and humidity signals, and the sensor control system is configured to generate one or more gas concentration signals indicative of the gas concentration in the gas flow based on the sonic signal, the temperature signal, and the humidity signal.

[0027] Preferably, the sensor control system may be configured to apply a temperature correction to the temperature signal to compensate for any predicted temperature detection error caused by the heat in the breathing apparatus that affects the temperature sensor.

[0028] Preferably, the sensor assembly may further include a flow rate sensor configured to detect the flow rate of the gas flow in the vicinity of the sensor assembly and generate a representative flow rate signal, and the system may further include a provided motor speed sensor configured to detect the motor speed of the blower unit and generate a representative motor speed signal, and the temperature correction is calculated by the sensor control system based at least on the flow rate signal and / or the motor speed signal.

[0029] [[ID=ll]] In one form, the sensor control system may be configured to generate a gas concentration signal representative of the oxygen concentration in the gas flow.

[0030] In another form, the sensor control system may be configured to generate a gas concentration signal representative of the carbon dioxide concentration in the gas flow.

[0031] Preferably, the sensor assembly may be detachably mounted in the flow path.

[0032] Preferably, the flow path may have a shape or configuration that promotes a stable flow of the gas flow in at least one section or part of the flow path.

[0033] Preferably, the flow path may have a shape or configuration that promotes a stable flow in the section or part of the flow path that includes the sensor assembly.

[0034] Preferably, the flow path may include one or more flow directors at or toward the gas inlet. More preferably, each flow director may be in the form of a bow-shaped fin.

[0035] In one embodiment, the flow path may comprise at least one helical portion or section that facilitates a stable flow of gas. Preferably, the flow path may comprise an inlet section extending between the gas inlet and the blower unit, the inlet section comprising at least one helical portion.

[0036] Preferably, the sensor assembly may be positioned in the helical portion of the flow path. More preferably, the helical portion comprises one or more substantially straight sections, and the sensor assembly is positioned in one of the straight sections.

[0037] Preferably, the sensor assembly may comprise a sensor housing comprising a body which is hollow and defined by a peripheral wall extending between a first open end and a second open end, thereby defining a sensing passage between the walls within the body, through which a gas flow can flow in the direction of a flow axis extending between the first and second ends of the body, and a pair of transmitter and receiver transducers are arranged on opposite walls or sides of the sensing passage. More preferably, the sensor housing may comprise a body which defines a sensing passage between a first end and a second end along the body, comprising two spaced-apart side walls and an upper and lower wall extending between the side walls, and a pair of transducer mounting assemblies arranged on opposite walls of the body, each of which is configured to receive and hold each transducer of the transducer pair so that each transducer of the transducer pair is aligned and faces each other across the sensing passage of the body.

[0038] Preferably, the blower unit may be operable to generate a gas flow at the gas outlet having a maximum flow rate of 100 liters / minute.

[0039] In one embodiment, the gas inlet may be configured to receive a supply of gas containing a mixture of atmospheric air and pure oxygen from an oxygen source. In another embodiment, the gas inlet may be configured to receive a supply of gas containing a mixture of atmospheric air and carbon dioxide from a carbon dioxide source.

[0040] Preferably, the flow path is located within the bulk flow path of the device.

[0041] In a second aspect, the essence of the present invention, in a broad sense, lies in a sensor assembly for detecting an inline flow path of gas flow within a respiratory assistance device, the sensor assembly comprising a sensor housing having a main body, the main body being hollow and defined by a peripheral wall extending between a first open end and a second open end, thereby defining a detection passage between the walls within the main body, through which the gas flow can flow in the direction of a flow axis extending between the first end and the second end of the main body, the sensor assembly comprising an ultrasonic gas composition sensor system mounted on the sensor housing for detecting one or more gas concentrations in the gas flow flowing through the detection passage, a temperature sensor mounted on the sensor housing for detecting the temperature of the gas flow flowing through the detection passage, and a flow sensor mounted on the sensor housing for detecting the flow rate of the gas flow flowing through the detection passage.

[0042] Preferably, the sensor housing may be configured to detachably engage with a complementary retaining aperture within the flow path of the respiratory support device.

[0043] Preferably, the ultrasonic gas composition sensor system may comprise a pair of transmitter and receiver transducers that can operate to transmit acoustic pulses from the transmitter to the receiver through the gas flow, in a direction substantially perpendicular to the flow axis of the gas flow flowing through the sensing passage.

[0044] Preferably, the transmitter transducer and receiver transducer pair may be placed on opposite walls or sides of the sensing passage.

[0045] Preferably, the sensor housing body comprises two spaced-apart side walls and an upper wall and a lower wall extending between the side walls, defining a detection passage along the body between a first end and a second end, and the body may comprise a pair of transducer mounting assemblies positioned on opposing walls of the body, each of which is configured to receive and hold each transducer of the transducer pair so that each transducer of the transducer pair is aligned and facing each other across the detection passage of the body.

[0046] Preferably, a pair of transducer mounting assemblies may be arranged on opposing side walls of the main body, and each transducer mounting assembly includes a retaining cavity that internally receives and holds each transducer in the pair.

[0047] Preferably, each transducer-mounted assembly may include a cylindrical base portion extending from each side wall of the main body and at least one pair of opposing clips extending from the base portion, the base portion and the clips together defining a retaining cavity.

[0048] Preferably, each side wall of the main body may be provided with a transducer aperture, which is aligned with the associated transducer mounting assembly, and through the transducer aperture, the operating front of the transducer can extend to access the sensing passage.

[0049] Preferably, the transducer-mounted assembly can be configured such that the working surface of each transducer is substantially flush with the inner surface of each wall of the sensor housing.

[0050] A second aspect of the present invention may have any one or more of the features described with respect to the sensor assembly of the first aspect of the present invention.

[0051] As used herein and in the claims, the term “stable flow” means a type of gas flow, whether laminar or turbulent, that promotes or causes to substantially maintain the substantially constant over time attributes or characteristics of the flow being measured or detected, under a given set of conditions, on a measure in which the attributes or characteristics are being measured or detected.

[0052] As used herein and in the claims, the terms “crossflow beam” or “crossflow” mean an ultrasonic pulse or beam transmitted in a beampath that crosses or traverses the main gas flow direction or axis, as opposed to being along the main gas flow direction, unless the context suggests otherwise. For example, a crossflow beam may be transmitted across the gas flow path in a direction substantially perpendicular to the main gas flow direction or axis, but other crossflow angles are also intended, which are covered by this term.

[0053] As used herein and in the claims, the terms “beam along the flow” or “along the flow” mean an ultrasonic pulse or beam that can be transmitted in the direction of the gas flow or against it, whether parallel or coincident, in a beam path substantially aligned with the direction or axis of the main gas flow path, unless the context suggests otherwise.

[0054] As used herein and in the claims, the term “equipped with” means “consisting of at least a part of.” When interpreting each sentence in this specification and in the claims that contains the term “equipped with,” there may be features other than the one or more features to which the term is followed. Related terms such as “equipped with” and “equipped with” should be interpreted similarly.

[0055] Numerical range References to numerical ranges disclosed herein (e.g., 1 to 10) are intended to incorporate references to all related numerical values ​​within that range (e.g., 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10), as well as any range of related numerical values ​​within that range (e.g., 2 to 8, 1.5 to 5.5, and 3.1 to 4.7), and therefore all subranges of all ranges expressly disclosed herein are also expressly disclosed. These are merely examples of what is particularly intended, and all possible combinations of numerical values ​​between the listed minimum and maximum values ​​should likewise be considered expressly described herein.

[0056] As used herein, the term "and / or" means "and" or "or" or both.

[0057] As used herein, "(s)" following a noun signifies the plural and / or singular form of that noun.

[0058] The essence of this invention lies as described above, but the following structures are also conceivable, although they merely provide examples.

[0059] Preferred embodiments of the present invention will be described with reference to the drawings, merely as examples. [Brief explanation of the drawing]

[0060] [Figure 1] This is a schematic diagram of a known form of respiratory support device having a modular blower unit connected to a humidifier unit. [Figure 2] This is a schematic diagram of another known form of respiratory support device in which the blower unit and humidifier unit are integrated into a single main housing. [Figure 3] A perspective view of the main housing of a respiratory support device according to one embodiment of the present invention is shown. [Figure 4] Figure 3 shows a side elevation view of the respiratory support device. [Figure 5] Figure 4 shows a front elevation view of the respiratory support device from direction A. [Figure 6] Figure 4 shows a rear elevation view of the respiratory support device from direction B. [Figure 7] Figure 3 shows a bottom view of the respiratory support device. [Figure 8] Figure 3 shows a plan view of the respiratory support device. [Figure 9] Figure 3 shows a perspective view of the respiratory support device, with the upper part of the main housing removed, exposing the electronic control circuit and blower unit compartment. [Figure 10] Figure 9 shows a perspective view of the respiratory assist device, with the electronic control circuit, external blower unit case, and other components removed, exposing the upper side of the internal blower case containing the motor and impeller. [Figure 10A] Figure 3 shows a perspective view of the respiratory support device, with the lower part of the main housing and the base section removed, exposing the lower parts of the main external blower unit case and the internal blower case. [Figure 11] Figure 10 shows a perspective view of the respiratory support device, with the internal blower case and humidification chamber inlet connector removed, exposing the upper part of the main housing base section. [Figure 12] Figure 11 shows a perspective view of the respiratory support device, with the lower part of the main housing removed, exposing the base compartment and humidifier unit compartment. [Figure 13] Figure 12 shows a plan view of the respiratory support device. [Figure 14] Figure 12 shows a rear end view of the respiratory support device from direction C. [Figure 15] Figure 12 shows a bottom view of the respiratory assistance device, illustrating a sensor assembly and a first embodiment of the inlet section of a gas flow channel having a spiral flow channel. [Figure 16] Figure 12 shows a lower perspective view of the respiratory support device. [Figure 17] Figure 12 shows an enlarged perspective view of the lower part of the respiratory support device, particularly the gas flow channel inlet section and a portion of the sensor assembly. [Figure 18A] Figure 12 shows a bottom view of the breathing apparatus, illustrating a sensor assembly and a second embodiment of the inlet section of a gas flow channel having a direct flow path. [Figure 18B] Figure 18A shows a rear end view of the respiratory support device having a direct inflow channel. [Figure 18C] Figure 18A shows a perspective view of the lower part of the respiratory apparatus. [Figure 19] A perspective view of the housing of a sensor assembly according to one embodiment of the present invention is shown. [Figure 20] Figure 19 shows a perspective view of the sensor assembly housing, which has a sensor configuration mounted within the housing. [Figure 21] Figure 19 shows a bottom view of the housing of the sensor assembly. [Figure 22] Figure 19 shows a top-down plan view of the sensor assembly housing. [Figure 23] Figure 19 shows a side view of the housing of the sensor assembly. [Figure 24] Figure 19 shows an end view of the housing of the sensor assembly. [Figure 25] A block diagram of a sensor control system for a respiratory assistance device according to one embodiment of the present invention is shown. [Figures 26A-26E] This diagram shows schematic representations of various ultrasonic transducer configurations for sensor assemblies using cross-flow beams. [Figures 27A-27C] This diagram shows schematic representations of various ultrasonic transducer configurations for sensor assemblies that use beams aligned with the flow. [Modes for carrying out the invention]

[0061] Overview The present invention relates primarily to a sensor assembly and associated sensor control circuit for detecting various characteristics of the gas flow through a respiratory assistance device. As an example, one embodiment of the sensor assembly and sensor control system will be described with reference to an integrated system type respiratory assistance device in which the blower unit and humidifier unit are integrated within a single housing. However, it will be understood that the sensor assembly and associated sensor control system may also be implemented in a modular type respiratory assistance device system in which the humidifier unit is separate from the blower unit.

[0062] Furthermore, the embodiments described refer in particular to respiratory support devices used in high-flow humidification and oxygen therapy, which can consider the gas stream as a two-component gas mixture of atmospheric air mixed with supplemental oxygen (O2) such that the oxygen concentration of the gas stream delivered to the end user has an increased oxygen concentration compared to atmospheric air. In the art, supplementing or mixing another gas with atmospheric gas is known as "augmentation" and is typically used to alter the concentration of a particular gas, such as oxygen or nitrogen, compared to its concentration in atmospheric air.

[0063] It will be understood that the sensor assembly and detection circuit may alternatively be configured specifically for other respiratory therapies such as PAP therapy, or implemented in other respiratory support devices that are specifically controlled for other therapies, regardless of whether they deliver a pressurized gas flow of atmospheric pressure alone or a pressurized gas flow of atmospheric air reinforced with another specific gas such as oxygen or nitrogen. While the sensor assembly and sensor control system are primarily configured to detect the oxygen concentration of a binary gas mixture containing oxygen-enhanced atmospheric gas, it will be understood that they may also be configured or adapted to detect the characteristics of gas flows containing other enhanced air mixtures or binary gas mixtures, such as atmospheric air enhanced with nitrogen (N2) from a nitrogen source, atmospheric air enhanced with carbon dioxide (CO2) from a carbon dioxide source or any other suitable supplemental gas, oxygen-enhanced helium, or any other suitable binary gas mixture.

[0064] Integrated respiratory support device for high-flow humidification and oxygen therapy. Referring to Figure 3, the main housing of an integrated respiratory support device 10 (breathing device) according to one embodiment of the present invention is shown. The breathing device 10 comprises a blower unit that generates a pressurized or high-flow gas stream, which is then heated and humidified by a humidification unit as described above. Although not shown in Figure 3, the gas stream generated by the breathing device 10 is typically delivered to the patient through a patient interface comprising a flexible delivery conduit or tube, the conduit or tube connected at one end to the gas outlet 12 of the breathing device 10 and at the other end to a user interface, which is typically a nasal cannula, or alternatively, a nasal mask, a full-face mask, a tracheostomy connector, or any other suitable user interface.

[0065] In this embodiment, the breathing apparatus 10 is provided with a humidification unit 15 of the type described above, for example, with reference to Figure 2. The humidification unit 15 comprises a humidification water chamber 17 and a heater plate 19, which are located in a humidification unit compartment, generally shown as 14, that is positioned at or toward the front end 11 of the main housing. Referring to Figures 3 and 5, the humidification chamber 17, if installed, is provided with an inlet port 16 and an outlet port 18 for connecting the chamber to the flow path of the breathing apparatus. For example, the inlet port 16 is connected to the flow path after the blower unit so that the humidification chamber 17 receives a pressurized or high-flow gas stream through the inlet from a blower unit located at or toward the rear end 13 of the main housing. Once heated and humidified, the gas stream exits the humidification chamber through the outlet port 18, which is fluidly connected to the gas outlet 12 of the breathing apparatus 10.

[0066] Referring to Figure 6, the gas inlet assembly 20 of the respiratory device 10 is shown at the rear end 13 of the main housing. In this embodiment, the gas inlet assembly 20 comprises one or more atmospheric air inlet valves 22 into which ambient atmospheric air is drawn into the device by a blower unit, and a supplement gas connection inlet 24, which may be connected to a central gas supply source of supplement gas, such as an oxygen stream, which is mixed with atmospheric air to increase the oxygen concentration. As will be described in more detail later, the two-component gas mixture of air and oxygen is drawn in or drawn in by the blower unit, pressurized, and becomes a gas stream of a desired flow rate to be subsequently sent to a humidification unit, where the gas stream is heated and humidified and then sent to the end user via the patient interface to complete the breathing circuit.

[0067] Referring to Figure 3, in this embodiment, the main housing of the respiratory apparatus 10 is a two-part structure including a lower housing 26, which is detachably coupled or fitted to the upper housing 28 and, when assembled together, forms a whole main housing or case that encloses the blower unit and provides a humidification unit compartment that receives the humidification chamber. However, it will be understood that a multi-part housing structure of three or more parts or a single integrated main housing may be used as an alternative. In this embodiment, the housing parts are molded from plastic, but it will be understood that, if necessary, one or more components or parts of the housing may be formed from other materials.

[0068] Referring to Figure 7, the main base or lower portion 26a of the lower housing 26 is shown. Referring to Figure 8, a user control interface 30 is provided on the main upper portion 28a of the upper housing 28, and the user control interface 30 may include a user control device and / or a user display for controlling the respiratory device 10.

[0069] Referring to Figure 9, the breathing apparatus 10 is shown with the upper housing 28 removed, exposing the main or external blower unit case 32 of the blower unit compartment, which is housed and positioned toward the rear end 13 of the main housing in this embodiment. A Pront circuit board 31, which contains the control system electronics of the breathing apparatus 10 and is mounted along the blower unit case 32, is also seen in Figure 9. Connectors and / or conduits 23, 25 that fluidly connect the inlet port 16 and outlet port 18 of the humidification chamber 17 to the blower unit and gas outlet 12, respectively, are also shown more clearly. Figure 10 shows the internal blower case 34, which houses the motor and impeller of the blower unit. The gas outlet of the blower unit is generally shown as 35. The internal blower case 34 is mounted or housed inside the main blower unit case 32 shown in Figure 9.

[0070] Referring to Figure 10A, the gas outlet 35 of the blower unit can be seen more clearly. The blower unit is also provided with a central gas inlet aperture or port 37, through which gas is drawn in by the rotating impeller of the blower unit. In this embodiment, the inlet port 37 of the blower unit is fluidly connected to the gas inlet assembly 20 by a flow path.

[0071] Referring to Figure 11, the base compartment 36 is located behind the blower unit and positioned toward or toward the rear end 13 of the main housing. In this embodiment, the base compartment 36 is mounted on or housed within the lower housing 26. The base compartment 36 has an outlet port or aperture 38 on its top or lid 36a, which is fluidly connected to the inlet port 37 of the blower unit by a conduit and / or connector so that, in operation, the gas flow enters the gas inlet assembly 20 and then flows from the base compartment 36 through the blower unit. Figure 12 shows the base compartment 36 more clearly with the lower housing 26 of the main housing omitted from the figure. The humidification unit compartment 14 is also more clearly visible in Figure 12.

[0072] gas flow path During operation, the gas flow is transported from the gas inlet assembly 20 to the gas outlet 12 via a flow path through the breathing apparatus 10. In this embodiment, the flow path begins at the gas inlet assembly 20, where a gas flow, such as atmospheric air mixed with supplemental oxygen, enters the breathing apparatus 10, is channeled or transported through the inlet section of the flow path in the base compartment 36, and then enters the blower unit compartment. After leaving the inlet section of the flow path, the gas flow enters the blower unit, where the gas is pressurized or accelerated to become a high-flow gas flow with a controllable flow rate, which is typically a high flow rate for high-flow humidification therapy. In such applications, the flow rate may be in the range of about 1 L / min to about 100 L / min, more preferably in the range of about 2 L / min to about 60 L / min. The flow path exits the blower unit and enters a humidification unit via a fluid connection (e.g., via conduits, connectors, and / or ports), where the gas flow is heated and humidified. The flow path ends where the gas flow is transported from the outlet 18 of the humidifying unit to the gas outlet 12 of the breathing apparatus 10.

[0073] It will be understood that certain portions or sections of the gas flow path, for example, the path after the humidification unit, can be completely sealed. Furthermore, the path may be sealed between the humidification unit and the blower unit, and the inlet section of the path before the blower unit can also be optionally substantially sealed along most of the path after the gas inlet assembly 20. It will be understood that the path transporting the gas flow can be defined by conduits, ports, and / or connectors that fluidly connect to various components, such as the blower unit to the humidification unit, and / or generally by the formation of housings and cases within the breathing apparatus, which can constitute enclosed channels or passages formed from inner walls or inner surfaces that direct the gas flow through the breathing apparatus.

[0074] Spiral inlet channel - First embodiment Figure 14 shows an inlet aperture 58 formed at the rear of the base compartment 36. The inlet aperture 58 is located behind the gas inlet assembly 20. A first embodiment of the inlet section of the gas flow path will be described with reference to Figure 15. The inlet section of the gas flow path is located within the base compartment 36 of the main housing and extends from the gas inlet assembly 20 at the rear of the breathing apparatus 10 to the outlet port 38 of the base compartment, and then enters the inlet port 37 of the blower unit. As shown in Figure 15, the inlet section of the flow path generally follows the path indicated by arrow XX.

[0075] In this embodiment, at least a portion of the inflow section of the flow path has a shape or configuration that promotes a stable airflow upon reaching the outlet port 38 and before entering the blower unit compartment through the outlet port 38. A stable airflow helps reduce noise and increase the accuracy of the sensing gas characteristics measured by the sensor assembly in the sensor zone of the flow path. In this embodiment, the stable flow is generated or provided by at least a portion of the inflow section of the flow path that is helical or provides a helical course or path. For example, as shown in Figure 15, at least a portion of the flow path indicated by arrow XX is in the form of a gradually tightening path. The terms “helical” or “spiral” are intended to mean any form of flow path that is continuous and gradually winds in one or more turns from a start point to an end point. It is intended to encompass any uniform or non-uniform helical path, regardless of whether it is a continuous, gradually tightening curve with a radius decreasing relative to a central point or central axis, where the radius reduction rate may be constant or variable, or whether the flow path is wound in a spiral toward a reference point located within the outermost winding (i.e., in at least one winding), regardless of whether the reference point is located in the center or not, and regardless of whether the flow path is wound in a spiral toward a reference point located within the outermost winding (i.e., in at least one winding).

[0076] The helical portion of the flow path may, depending on the design requirements, form a large portion of the entire inflow section of the flow path, or alternatively, a small portion of the inflow section of the flow path. In this embodiment, the helical portion of the flow path generally begins at a location indicated by 42 and ends at a location indicated by 44 after one inward helical winding. The inflow section of the flow path begins in an inlet zone indicated as a whole by 46, with an initial section or portion before the start of the helical portion 42, and ends in an ending section or portion indicated as a whole by 48, after the end of the helical portion 44. In this embodiment, the ending of the inflow section of the flow path is in the form of a gradually winding flow path that opens toward a larger transition zone 48 in which an outlet port 38 to a blower unit is located. The transition zone 48 has a substantially curved circumferential wall, which may substantially coincide with at least a portion of the circumference, or be curved in other ways when viewed in plan, or be concave. In Figure 15, the circumferential wall section of the transition zone is defined between 50 and 52 with a central point Y within the transition zone 48. The shape of the walls within the transition zone is configured to promote a stable flow of gas as it exits the inlet section of the flow path and enters the blower unit.

[0077] As described above, the flow path within the respiratory apparatus 10 may be formed from a combination of conduits, tubes, housings, or cases of the respiratory apparatus, including connectors, ports, and / or other joints that fluidly connect various sections of the flow path. In this embodiment, the inlet section of the flow path is substantially defined by two walls 54 and 56 of equal width, spaced apart from each other and enclosed within the base compartment, forming a conduit, channel, or passage enclosed by horizontally extending upper and lower walls or surfaces such as the upper cover 36a of the base compartment and the base or lower side 26a of the lower housing 26 of the main housing (see Figure 7). As shown in this embodiment, the walls 54, 56 are upright and extend substantially perpendicular or substantially perpendicular to the substantially horizontal enclosing upper cover 36a of the base compartment and the lower side 26a of the lower housing 26. It will be understood that the walls 54 and 56 of equal width may alternatively be enclosed from above and / or below by one or more flat plates or members. In this embodiment, the flow path, at least the flow path within the helical portion of the inflow section, has a substantially rectangular or square cross-sectional shape, but it will be understood that this is not essential. In alternative embodiments, the flow path may be configured to have any other desired cross-sectional shape, including circular, elliptical, or other shapes, and the shape may be uniform along the length of the flow path, or may vary between two or more shapes and / or sizes. It will also be understood that the inflow section, in particular the helical portion of the inflow section of the flow path, may be formed from a rigid conduit or tube formed to extend in a desired helical shape.

[0078] In this embodiment, the cross-sectional area of ​​the helical portion of the inflow section of the flow path is substantially uniform along the length of the helical portion, but in an alternative embodiment, the cross-sectional area may be non-uniform along the length of the helical portion. In particular, the width (W) between walls 54 and 56 that extend to the same extent is substantially constant throughout the entire helical portion of the inflow section in this embodiment, but may be variable along the length of the helical portion in an alternative embodiment, if necessary. Referring to Figure 17, the wall height (H) is also preferably constant along at least the helical portion of the inflow section of the flow path, but in other embodiments, it may be configured to be variable, if necessary.

[0079] In this embodiment, the entire inflow section of the flow path extends substantially in the same plane within the base compartment 36 such that there is no vertical displacement or shift of the flow path within the inflow section, or at least within the helical portion of the inflow section, until the flow path transitions to the outlet port 38, at which point the flow path extends vertically into the blower unit case 32 above the base compartment 36.

[0080] In this embodiment, there is a single helical section substantially located before the transition zone of the flow path, where the flow path enters the blower unit section 32. However, in alternative embodiments, it will be understood that the flow path may comprise two or more separate helical sections arranged in series within the flow path. If there are multiple helical sections, they may all be located before the blower unit, or they may be located after the blower unit and before the humidifier unit, or alternatively, at least one helical section may be provided in each region. In a preferred embodiment, one or more helical sections are preferably provided before the flow path enters the humidifier unit, and more preferably before the flow path enters the blower unit or any other section of the flow path where the facilitation of a stable flow is beneficial for noise reduction or gas flow characteristic detection accuracy.

[0081] Sensor assembly Referring to Figures 15-17, the breathing apparatus 10 includes a sensor assembly 60 positioned or installed along the flow path in front of the humidification unit for detecting various characteristics or parameters of the gas flow. In this embodiment, the sensor assembly 60 is located in a sensor zone of the inflow section of the flow path, preferably within the helical portion of the inflow section of the flow path when the gas flow has stable flow characteristics. The sensor assembly 60 includes a sensor housing shown in Figures 16 and 17, configured or adapted to receive and hold one or more sensors, sensor components, or sensor devices for detecting or sensing one or more characteristics of the gas flow flowing through the flow path. For clarity, Figures 16 and 17 show the housing of the sensor assembly 60 without any sensors. The housing and sensors will be described in further detail with reference to Figures 19-24.

[0082] In this embodiment, the sensor housing is a modular component that is detachably fixed, mounted, engaged, held, or fitted within the flow path so that it can be removed for replacement, maintenance, or repair if desired. In this embodiment, the flow path walls 56 and 54 in the inflow section are discontinuous within the substantially straight section 61 of the flow path, thereby providing a receiving or mounting slot, aperture, groove, or gap from which the sensor housing of the sensor assembly 60 can be received and held. When installed, the housing of the sensor assembly bridges the holding gap provided by the discontinuous walls 54, 56 to complete the flow path. Using this configuration, the sensor assembly 60 is configured to provide detection of one or more characteristics of the gas flow in the bulk flow path or main flow path of the breathing apparatus. In other words, the sensor assembly 60 is not located in a separate chamber or auxiliary flow path relative to the bulk flow path or main flow path through the breathing apparatus.

[0083] In this embodiment, the sensor housing is configured to be received and held within the mounting aperture of the flow path via a friction fit. However, it will be understood that any other detachable mounting configuration or retention system, including a clip system, a latch system, a snap fit, or any other detachable configuration, may be used as an alternative.

[0084] The sensor assembly 60 may be configured or adapted to include one or more sensors for detecting one or more characteristics of the gas flow in the flow path. Any suitable sensor may be mounted in the sensor housing, as understood. In this embodiment, the sensor assembly comprises at least a gas composition sensor for detecting or measuring the gas composition or concentration of one or more gases in the gas flow. In this embodiment, the gas composition sensor is in the form of an ultrasonic gas composition sensor system that utilizes ultrasound or sound waves to determine the gas concentration. In particular, the ultrasonic gas composition sensor utilizes binary gas detection or analysis to determine the relative gas concentrations of two gases in a binary gas mixture. In this embodiment, the gas composition sensor is configured to measure the oxygen concentration in a bulk gas flow, which consists of supplemented oxygen-enhanced atmospheric air, which is essentially a binary gas mixture of nitrogen (N2) and oxygen (O2). It will also be understood that the ultrasonic gas concentration sensor may be configured to measure the gas concentration of other enhancement gases mixed with atmospheric air in the gas flow, including two gases, nitrogen (N2) and carbon dioxide (CO2) or any other ratio. For example, an ultrasonic gas concentration sensor may be configured to measure carbon dioxide (CO2), deliver a controlled level of CO2 to the patient, and control the patient's breathing pattern. By adjusting the level of CO2 delivered to the patient, the patient's Cheyne-Stokes respiration can be controlled. Controlling a patient's breathing pattern may be useful in several situations, such as athlete training that simulates high-altitude conditions.

[0085] As described above, in this embodiment, the breathing apparatus 10 comprises a gas inlet assembly 20, which is configured to receive ambient air and supplemental gases such as oxygen from an oxygen supply line or gas bottle. However, it will be understood that the air supply does not necessarily have to be ambient, and air may be supplied to the gas inlet assembly from an air supply line or gas bottle. Furthermore, it will be understood that the breathing apparatus 10 does not necessarily have to receive an air supply. The breathing apparatus 10 may be configured to receive a supply of any two or more gases suitable for mixing and subsequently delivering to the end user via the patient interface. The gases may be supplied to the gas inlet assembly of the breathing apparatus by any suitable means, including from a central gas supply line, from a gas bottle, or in any other manner.

[0086] In this embodiment, the sensor assembly 60 also includes a temperature sensor configured to measure the temperature of the gas flow and a flow sensor configured to detect the flow rate of the gas flow in the flow path.

[0087] Direct inlet channel - Second embodiment A second embodiment of the inlet section of the gas flow channel within the base compartment 36 will be described with reference to Figures 18A to 18C. Similar reference numerals in the drawings represent components similar to those of the helical inlet channel in the first embodiment described with reference to Figures 14 to 17. In this second embodiment, the inlet section of the channel is a shorter and more direct channel between the inlet aperture 58 and the outlet port 38 of the base compartment 36. The shorter and more direct channel reduces the gas residence time in the base compartment, thereby reducing the heating of the gas due to the surrounding electronic components.

[0088] In this embodiment, the inlet flow path can be defined by three main zones or main regions extending between the inlet aperture 58 and the outlet port 38. The three regions are the inlet zone 39, the sensor zone 41, and the transition zone 43.

[0089] Referring to Figure 18A, the inlet zone or region 39 extends between the inlet aperture 58 and the transition line EE approximately before the sensor zone 41. In this embodiment, the inlet zone 39 of the inlet flow path is defined between two walls 45 and 47, which extend in or toward the inlet aperture 58 to the sensor assembly 60. In this embodiment, the cross-sectional area of ​​the inlet zone 39 gradually decreases or diminishes toward the transition line EE from the inlet aperture 58 to the sensor zone 41, thereby forming a funnel-like shape for the walls in the inlet zone. For example, the side walls 45 and 47 have a greater displacement from each other in the inlet aperture 58 relative to their displacement from each other in or toward the transition line EE. In other words, this distance or displacement between the side walls 45 and 47 decreases from the inlet aperture 58 towards the transition line EE, so that the inlet zone 39 begins with a wide opening at the inlet aperture 58 and the flow path gradually narrows toward the transition line EE before the sensor zone 41. This funnel-like configuration of the inlet zone creates an accelerated gas flow, which facilitates a more stable gas flow in the subsequent sensor zone.

[0090] Optionally, one or more flow directors 49 may be provided in the inlet zone 39. In this embodiment, the inlet zone 39 is curved in that it is not a direct, straight flow path from the gas inlet assembly to the sensor zone, which may create uneven flow or velocity gradients across the inlet flow path in one or more regions of the inlet flow path. To compensate for this, the inlet zone 39 is provided with a plurality of flow directors 49, which are in the form of arched or curved fins (clearly shown in Figure 18C) configured or provided with an outline or shape that helps to promote a uniform airflow to the sensor zone 41, not biased toward any particular wall of the flow path. The number and shape or outline of the flow directors 49 may be modified to help direct the airflow to the sensor zone 41 at a desired angle, but it will be understood that preferably the bulk flow is configured to enter the sensor zone in a direction substantially perpendicular to the transition line EE or the front opening of the sensor assembly 60. In this embodiment, the fins 49 help provide a stable flow through the sensor zone 41. Referring to Figure 18B, the fins 49 may also function as tamper-proof or protective guards to prevent user access to the sensor assembly 60, which may contain delicate or calibrated sensor components. In this embodiment, the fins 49 are integrally formed with the top cover 36a of the base compartment 36 and suspended downward from the top cover 36a into the inlet zone, but it will be understood that the fins may alternatively be integrally formed with the base or lower side 26a of the lower housing 26, or mounted so as to extend upward from the base or lower side 26a into the inlet zone. It will also be understood that the fins do not necessarily have to be oriented vertically and may alternatively be oriented horizontally so as to extend from the side walls of the inlet zone of the inlet flow path, or at any other suitable angle or mixture of angles.

[0091] Sensor zone 41 is defined approximately between the end of the inlet zone at the transition line EE and the beginning of the transition zone 43 at the transition line FF. The sensor zone comprises a modular, detachable sensor assembly 60 of the type described above with reference to Figures 15-17, and which is known to be positioned in the bulk flow path to detect various characteristics or parameters of the gas flow. As shown, the ends of the side walls 45, 47 extend into the open front side of the sensor assembly 60, and the end of the loop wall 51 of the transition zone 43 extends into the opposite rear outlet side of the sensor assembly 60. Similar to the embodiments described with reference to Figures 15-17, the sensor assembly 60 is detachably held within a retaining gap provided or formed between the ends of the side walls 45, 47 and the loop wall 51.

[0092] The transition zone 43 is defined by a substantially curved peripheral wall or loop wall 51, which may substantially coincide with at least a large portion of the circumference, or may curve in other ways or take a concave shape when viewed in plan. In this embodiment, the loop wall 51 may extend circumferentially around a center point 53. The opening to the transition zone 43 is defined by the end of the loop wall, which extends outward relative to the center point 53 and engages with the outlet side of the sensor assembly 60. As shown, the substantially circular or spherical transition zone 43 has an outlet for the airflow through an outlet port 38 provided in the top cover 36a of the base compartment 36.

[0093] Similar to the spiral inlet channel embodiment described with reference to Figures 14-17, the shorter direct inlet channel in Figures 18A-18C is also enclosed from above and below by horizontally extending upper and lower walls or surfaces, forming an enclosed channel or air passage. The channel is mainly defined by side walls 45, 47 and loop wall 51 that extend to the same width, and these side walls are enclosed from above and below, for example, by the top cover 36a of the base compartment and the base or lower side portion 26a of the lower housing 26 of the main housing (see Figure 7). As shown, in this embodiment, the side walls 45, 47, and 51 are upright and extend substantially perpendicular to or substantially perpendicular to the substantially horizontal enclosing top cover 36a of the base compartment and the lower side portion 26a of the lower housing 26.

[0094] Sensor housing and position In the above embodiment, the sensor assembly 60 is located in the sensor zone, and the inlet section of the flow path is in front of the blower unit. However, the sensor assembly may alternatively be located in a sensor zone in any other suitable portion of the flow path in front of the humidifier unit. In particular, the sensor zone of the flow path can be located at any position in the flow path upstream (i.e., in front of) the humidifier unit, including before or after the blower unit.

[0095] The sensor housing and sensors of the sensor assembly 60 will now be described in more detail. The sensor assembly can be used in either a helical or direct inlet flow channel embodiment, as described with reference to Figures 14 to 18C. Referring to Figures 19 to 23, the sensor assembly 60 comprises a sensor housing 62, which houses one or more sensors for measuring various characteristics of the gas flow in the bulk flow channel. In this embodiment, the sensor housing 62 comprises a central body 63 extending between a first end 74 and a second end 76. The body 63 is hollow and has openings at both ends, thereby providing a passage or sensing passage 86 through which the gas flow passes from the first end 74 to the second end 76 of the body 63. In particular, the gas flow generally flows in the direction of the flow axis 110 shown in Figure 20, extending from the first end 74 to the second end 76 of the body 63.

[0096] In this embodiment, the body 63 is formed between a first end 74 and a second end 76 by two spaced-apart vertical side walls 64 and 66, and an upper wall 68 and a lower wall 70 extending horizontally between the vertically extending side walls 64 and 66, and the walls collectively form and define a sensing passage. The body is open at both ends 74 and 76, and in use, both ends 74 and 76 are aligned with the flow path direction so that the gas flow moves through the hollow interior or cavity of the body defined by the inner surfaces of the side walls, upper wall, and lower wall. In this embodiment, the width W between the side walls 64 and 66 and the height (H) between the upper wall 68 and the lower wall 70 substantially correspond to the cross-sectional dimensions of the portion or section of the flow path that directly surrounds either side of the sensor assembly.

[0097] Sensor installation Temperature sensor and flow sensor Referring to Figures 19, 20, and 22, this embodiment of the sensor assembly is provided with mounting apertures 78, 80 for receiving and holding a temperature sensor 82 and a flow sensor 84. For example, the temperature sensor mounting aperture 78 is provided on the upper wall 68 of the main body of the sensor housing and is configured to receive and hold the temperature sensor. Similarly, a separate flow sensor mounting aperture 80 is provided on the upper wall 68 of the main body 63 of the sensor housing 62 and has a shape or configuration for receiving and holding the flow sensor. The sensors 82 and 84 may be held within each mounting aperture 78, 80 by friction fitting, snap fitting, or any other coupling or fixing configuration. The temperature sensor may optionally be provided with an infrared radiation shielding component.

[0098] Referring to Figure 20, the temperature sensor 82 and the flow sensor 84 are mounted so as to be suspended downward from the upper wall 68 of the main body 63 into the sensing passage 86. Preferably, the temperature sensor 82 and the flow sensor 84 are suspended approximately in the center between the ends 74 and 76 of the main body. The sensors 82 and 84 do not necessarily have to be suspended from the upper wall, nor do they necessarily have to be oriented vertically. In other embodiments, the sensors 82 and 84 may be mounted or fixed to any wall of the upper wall, lower wall, or side wall of the main body 63 of the sensor housing. Furthermore, the orientation of the sensors 82 and 84 from the support wall or mounting wall to the sensing passage may be vertical, horizontal, or any other suitable angle. The sensors 82 and 84 do not necessarily have to be centrally located relative to the support wall, and may be located at any suitable position, in the center, or elsewhere within the sensing passage. The sensors 82 and 84 may also extend from the same or different support walls.

[0099] In this embodiment, the temperature sensor 82 may be monolithic, digital, IC, or a temperature transceiver, but any alternative type of temperature sensor, whether analog or digital, can be used. In this embodiment, the temperature sensor 82 is a silicon bandgap temperature transceiver.

[0100] In this embodiment, the flow sensor 84 comprises a hot-wire anemometer (HWA) flow detector. In one embodiment, the flow sensor 84 is a constant-resistance HWA, in which case the detector comprises a temperature-controlled heated bead thermistor located in the sensing passage, from which the flow rate can be determined based on the energy (current) required to maintain the bead at a preset temperature. The preset temperature is preferably configured to be at a level that does not significantly alter the local temperature of the gas flow through the sensing passage in the context of O2 measurement. In other embodiments, the flow sensor 84 may comprise a constant-current HWA, in which case it will be understood that the flow rate is determined from the change in the resistance of the heated bead. It will be understood that any other suitable form of flow sensor or detector may be used if necessary.

[0101] Ultrasonic gas composition sensor system In this embodiment, an ultrasonic gas composition sensor is implemented and configured to detect the relative gas concentration of a two-component gas mixture in a gas stream using non-invasive cross-flow beam, ultrasonic pulse, or wave-based two-component gas analysis, as will be described in more detail later.

[0102] The sensor housing comprises transducer mounting assemblies, collectively designated 90 and 92, that receive and hold ultrasonic transducer components of the ultrasonic gas composition sensor system. In this embodiment, the transducer mounting assemblies 90 and 92 are located on opposite sides of the main body 63, thereby supporting or mounting a pair of transducers on opposite sides of the sensing passage 86. The transducers are aligned with the sensing passage 86 and face each other across the sensing passage 86. The transducer mounting assemblies 90 and 92 are mounted or fixed to the respective side walls 64 and 66 of the main body. Each transducer mounting assembly or formation is configured to provide holding cavities 90a and 92a of a size and shape that receive and hold transducer components of complementary sizes and shapes of the gas composition sensor system. In this embodiment, the receiving cavities 90a and 92a are substantially cylindrical and are aligned with or coaxial with circular transducer apertures provided through the respective side walls 64 and 66 of the main body. Figure 19 shows the transducer aperture 66a of the side wall 66, while the side wall 64 similarly has a corresponding transducer aperture, although this is not visible. In an alternative embodiment, it will be understood that transducer pairs can be mounted on the upper wall 68 and lower wall 70 of the main body, and the remaining temperature sensor 82 and flow sensor 84 are mounted so as to extend from either side wall 64, 66 into the sensing passage.

[0103] Referring to Figures 23 and 24, in this embodiment, each transducer mounting assembly 90, 92 has a cylindrical base portion 90b, 92b, which at one end is fixed to or mounted on the outer surfaces of the side walls 64, 66 of the main body 63, and at the other end is provided with at least one pair of opposing clips, clip portions, or fingers 90c, 92c extending from the cylindrical base portion. The cylindrical base portions, in combination with extension clips, collectively define a holding cavity 90a, 92a, within which the transducer components are securely received and held. In this embodiment, each transducer mounting assembly is provided with a circular array of clips or clip portions 90c, 92c spaced apart around the entire circumference of the cylindrical base portion 90b, 92b. In this embodiment, six clip portions 90c, 92c forming three opposing pairs are provided, but it will be understood that the number of pairs of clip portions may be changed if necessary.

[0104] The clip portions 90c and 92c may be elastically flexible, thereby allowing them to bend slightly outward relative to the axes of the respective receiving cavities 90a and 92a, indicated by 90d and 92d, respectively. The clip portions 90c and 92c may also be configured to taper in the direction toward the respective cavity axes 90d and 92d as they extend away from the respective cylindrical base portions 90b and 92b. This provides a cylindrical retaining cavity having dimensions that decrease in diameter or gradually taper as it extends away from the base portions 90b and 92b. As shown in Figure 24, each clip portion 90c and 92c, when viewed in cross-section along the length extending away from the associated cylindrical base portions 90b and 92b, is substantially arc-shaped or concave, thereby coinciding with the circumference of the cylinder. Referring to Figure 23, for example, each clip portion extends between a first end 94 located on the cylindrical base portion 90b and a second end or end 96 defining the end of the transducer receiving cavity 90a. In this embodiment, the inner surface of each clip portion toward the end 96 is provided with a ridge or shoulder portion 97, which extends into the retaining cavity and is configured to function as a stop or grip formation that secures the transducer component within the retaining cavity.

[0105] When installing typically cylindrical transducer components within each transducer mounting assembly 90, 92, the clip portions 90c, 92c flex slightly outward when the transducer component is partially inserted, and then return to their respective resting positions when the transducer is fully engaged within the cavity, thereby firmly gripping or holding the transducer within their respective holding cavities.

[0106] It will be understood that, if necessary, other transducer mounting assemblies may be used as alternatives to receive and hold the transducer elements within the sensor housing. Preferably, the transducer mounting assembly is configured to detachably secure the transducer components so that the transducer can be removed from the sensor housing for replacement or repair if necessary.

[0107] In this embodiment, the main body 63 and the transducer mounting assembly are integrally formed from a suitable material such as plastic. However, it will be understood that the sensor housing parts may be formed separately and then fixed or connected together.

[0108] Referring to Figure 20, transducers 100 and 102 are shown installed in the transducer mounting assemblies 90 and 92 of the sensor housing. In this embodiment, the transducers and transducer mounting assemblies are configured such that the front surfaces of the transducers extend into the respective transducer apertures in the side walls 64 and 66 of the main body 63, thereby cooperating to be in the same plane as the remaining inner surfaces of the side walls. For example, referring to Figure 20, the front surface 102b of transducer 102 is shown to be in substantially the same plane as the inner surface 66b of the side wall 66. The same configuration is provided for the opposing transducer components 100.

[0109] As shown, this configuration provides a pair of transducers 100, 102 which are aligned with each other and face each other across the sensing passage 86 of the main body 63, so that ultrasonic waves are transmitted in the direction of the gas flow moving through the passage 86 from the first end 74 to the second end 76 of the main body or in a direction substantially perpendicular to the flow axis 110.

[0110] The distance between a pair of transducers 100, 102 that define the acoustic beampath length (e.g., indicated by W in Figure 19) is selected to be large enough to provide the desired sensitivity, but short enough to avoid phase wrap-around obscurity. For example, the distance between transducers is selected to be large enough to increase sensitivity, but is limited based on the expected total phase shift for the range of gas composition and temperature being detected.

[0111] Sensor control system and circuit Referring to Figure 20, the electrical terminals or connectors 100a, 102a of transducers 100, 102 protrude from the side of the main body 63 of the sensor housing, and the electrical terminals 82a, 84a of temperature sensor 82 and flow sensor 84 are accessible from the outer surface of the upper wall 68 of the main body 63. A flexible wiring fabric or tape 112 may extend across the side and top surface of the sensor housing to provide wiring connections to the electrical terminals of the sensors. The wiring 112 extends to the sensor control system and circuit of the breathing apparatus 10, which is configured to control the sensors as will be described further later.

[0112] Referring to Figure 25, an example of a sensor control system 150 electrically connected to sensor components 100, 102, 84, and 82 via wiring 112 will be described. It will be understood that the electronic sensor control system 150 can be implemented in software or hardware, including implementation in any programmable device such as a microprocessor, microcontroller, or digital signal processor, and that it may have memory and associated input / output circuits as appropriate. It will be understood that the various modules of the sensor control system 150 may be diverse, further separate, or integrated, and that Figure 25 is described as merely an example of the general function of the sensor control system. The sensor control system 150 may be integrated with the main control system of the respiratory device, or it may be a separate subsystem that communicates with the main controller or control system. The sensor control system 150 will be described with reference to a specific arrangement or configuration of sensors arranged to identify the gas composition or relative concentration of gases in a two-component gas mixture, such as an air / oxygen mixture which is substantially equivalent to a nitrogen / oxygen mixture. However, it will be understood that the sensor control system may be configured to provide information indicating the concentration of other gases in the gas stream.

[0113] Flow module The flow sensor 84 is configured to detect the flow rate of the gas flow 110 flowing through the detection passage 86 of the sensor housing, for example, in units of liters per minute, and to generate a representative flow signal 152, which is received and processed by a flow module 154 in the sensor control system 150. A motor speed sensor 120 is also preferably provided in the blower unit to detect the motor speed, for example, the revolutions per minute (rpm) of the blower unit motor. The motor speed sensor 120 generates a representative motor speed signal 156, which is received and processed by a motor speed module 158.

[0114] Temperature module The temperature module 160 is configured to receive and process a temperature signal 162 generated by a temperature sensor 82, which represents the temperature of the gas flow through the sensing passage 86 of the sensor housing. In this embodiment, the temperature sensor 82 is configured to detect the temperature of the gas flow near the acoustic beam path between transducers 100 and 102.

[0115] The temperature module 160 is optionally configured to apply temperature compensation to the temperature signal 162 to compensate for potential errors or offsets generated by the temperature sensor 82. In particular, since the sensor assembly 60 is located after the blower unit compartment and other electronic circuits, heat from the circuits and motor may affect the temperature detected by the temperature sensor 82 depending on the operating conditions. For example, due to heat above the sensor assembly, the temperature signal 162 may show a gas flow temperature higher than the true temperature. To compensate for this potential error under certain operating conditions, the temperature module 160 is configured to apply a temperature compensation coefficient or correction based on the following formula: T corrected =T sensor +ΔT. During the ceremony: ·T corrected This is the corrected temperature after compensation. ·T sensor This is the temperature detected by the temperature sensor 82, represented by signal 162. ΔT is the temperature error calculated or predicted based on the current operating status of the respiratory device. That is the case.

[0116] The temperature error (ΔT) is changed according to the operating conditions of the breathing apparatus 10. In this embodiment, the temperature error is calculated based on the proportional relationship between the current gas flow rate 152 in the breathing apparatus and the current motor speed 156 and the system conditions. Typically, an increase in flow rate has a cooling effect, while an increase in motor speed increases heating inside the breathing apparatus housing due to increased power consumption. In operation, the temperature module is configured to continuously or periodically calculate the temperature error ΔT based on the current system operating conditions, particularly the current flow rate 152 and motor speed 156. The updated temperature error ΔT is then used to calculate the input temperature T detected from the temperature sensor. sensor Applied to 162, corrected temperature T corrected Generates.

[0117] In one embodiment, ΔT = α × (motor speed / flow rate), where α is a constant. However, it will be understood that, alternatively, ΔT may be calculated based on a reference table or other algorithm that takes into account one or more other operating conditions or system variations that affect temperature fluctuations likely to occur in the vicinity of the temperature sensor 82 in relation to the operation of the respiratory apparatus. In some embodiments, ΔT may incorporate time-dependent effects that affect temperature fluctuations, such as heat accumulated in the respiratory apparatus during long-term operation. For example, ΔT may also be expressed as an integral-differential equation that represents a time-varying effect, such as one attributable to the thermal capacitance of one or more parts of the respiratory apparatus.

[0118] Gas composition module The gas composition sensor system is configured as an ultrasonic two-component gas detection system. As described above, the gas composition detection system in this embodiment comprises a pair of ultrasonic transducer components 100, 102 provided on both sides of the detection passage of the sensor housing. One of the transducer components, 100, is configured as an ultrasonic transmitter that transmits unidirectional ultrasonic waves or acoustic beam waves or pulses across the passage to the other ultrasonic transducer in a direction substantially perpendicular to the direction of the gas flow through the detection passage, and the other ultrasonic transducer is configured as an ultrasonic receiver that receives the transmitted ultrasonic waves or pulses on the other side of the passage. In this embodiment, the transducer components 100, 102 may typically be piezoelectric ceramic transducer elements operating in a narrow bandwidth or any other suitable, operable ultrasonic transducer elements. In this embodiment, the transducer elements operate at a frequency of about 25 kHz, but this can be changed as desired. In a preferred form, the operating frequency is selected to be above the human audible acoustic spectrum and / or high enough to reduce or minimize interference from noise sources, so that gas composition detection is silent to the user.

[0119] The ultrasonic transmitter 100 and receiver 102 are controlled by the driver circuit 170 and receiver circuit 172 of the gas composition module 174, respectively. In particular, the driver circuit 170 provides a control excitation signal 176 to the ultrasonic transducer to drive the ultrasonic transducer to transmit pulses of ultrasonic energy. The ultrasonic receiver 102 detects the pulses and generates a representative received signal 178, which is received and processed by the receiver circuit 172. In this embodiment, a pulse system is used, but in alternative embodiments, a continuous wave or standing wave method may be used.

[0120] Ultrasonic two-component gas analysis is based on detecting the velocity of acoustic pulses through a gas sample, which is the bulk flow or main stream of the gas flow, through the sensing passage 86 of the sensor housing. The velocity of sound is a function of the average molecular weight and temperature of the gas. In this configuration, the gas composition module 174 receives a temperature signal 164 from the temperature module 160, representing the indicated temperature of the gas flowing between the beam paths between the ultrasonic transducers. Using knowledge of the detected velocity of sound and the detected temperature, the gas composition of the gas flow can be determined or calculated. In particular, using the measured velocity of sound across the sensing passage, the ratio of two known gases can be estimated by referencing empirical relationships stored in the form of reference tables, standard algorithms, or data, as is known in the field of ultrasonic two-component gas analysis. Alternatively, if a temperature sensor is not available, it will be understood that an estimate of the temperature of the gas flow in the beam path of the ultrasonic transducer may be used in the two-component gas analysis calculation. In such alternative embodiments, the temperature of the gas flow may be adjusted or controlled to be within a narrow temperature range so that an estimate of the temperature of the gas flow in the beam path can be used.

[0121] In some embodiments, the breathing apparatus may also be equipped with a humidity sensor, which is placed in the flow path and configured to generate a humidity signal indicating the humidity of the gas flow through the sensor assembly. In such embodiments, the gas composition may be determined by the detected speed of sound and the detected temperature and / or humidity. The humidity sensor may be a relative humidity sensor or an absolute humidity sensor. In some embodiments, the gas composition may be determined based on the detected speed of sound and the detected humidity without requiring a temperature sensor.

[0122] A gas composition detection system can be used to measure the ratio of any two known gases in a gas composition. In this embodiment, the gas composition module is configured to determine the relative gas concentrations in a mixture of supplemental oxygen-mixed air, which is substantially equivalent to a nitrogen / oxygen mixture. In such a two-component gas mixture, the average molecular weight of the gases can be determined by monitoring the speed of sound and taking temperature into account, and thus the relative concentrations of the two gases can be determined. From this ratio, the oxygen or nitrogen concentration of the gas stream can be extracted.

[0123] In this embodiment, the gas composition module 124 comprises an analyzer or controller 180, which is configured to operate ultrasonic transducers 100, 102 via driver circuits 170 and receiver circuits 172 using control signals 171, 173. The analyzer 180 is also configured to receive and process a corrected temperature signal 164 from the temperature module 160. In operation, the analyzer 180 is configured to periodically transmit unidirectional ultrasonic or acoustic pulses across a sensing path at a desired frequency to determine the velocity of sound of the acoustic pulses. The measured velocity of sound is then used, along with knowledge of temperature from the temperature module 160, to determine the gas composition. The velocity of the acoustic pulses can be determined in any desired manner, including by using a timer circuit to measure the travel time of the acoustic pulses moving directly or indirectly from transmitter 100 to receiver 102 across the path via phase detection. It will be understood that, if appropriate signal processing is implemented, the phase can be tracked to minimize the effects of "wrap-around". The distance between transducer elements 100 and 102 is known and is similar to the width between the side walls 64 and 66 of the sensor housing (W in Figure 19). Therefore, the sound velocity can be determined based on the travel time and the distance between transducers (corresponding to the beam path length). In particular, the analyzer may be pre-programmed with any other generally valid or instrument-specific data useful in determining the gas composition via the distance between transducers and / or sound velocity detection, and may be calibrated using this data. Calibration may take into account the change in the distance between transducer elements 100 and 102 as a function of temperature. For example, the distance between the side walls 64 and 66 of the sensor housing may increase or decrease as the temperature changes.

[0124] Optionally, the gas composition sensor module may be configured with user-selectable or pre-programmed scaling or correction factors to take argon into account when determining the oxygen concentration used when oxygen is supplied to a breathing apparatus from a commercially available oxygen concentrator using a pressure swing adsorption method. For example, the user may activate the control system and use the argon scaling or correction factor to change the detected oxygen concentration to remove any argon components and obtain a calculated oxygen concentration.

[0125] The sensor control system 150 may output data or signals indicating various characteristics detected by the sensor assembly or other sensors. For example, the output signals or data 182, 184, and 186 from modules 154, 158, and 160 may represent the detected flow rate 182, motor speed 184, and temperature 186. Similarly, the gas composition module is configured to generate one or more output signals or data 188 indicating the gas composition detected by the ultrasonic gas composition detection system. In this embodiment, the output signal 188 may represent the oxygen percentage or oxygen (O2) concentration in the gas stream. Alternatively, the signal or additional signal may represent the nitrogen (N2) concentration or percentage. It would also be understood that the system may be modified to provide signals representing the concentrations of other gases in the gas stream, including but not limited to carbon dioxide (CO2), for example.

[0126] Next, the main controller of the respiratory device may receive and process one or more gas concentration output signals 188. For example, the main controller may be configured to display the detected oxygen reading on the respiratory device's output display based on the oxygen signal 188. In one embodiment, the user control interface 30 (see Figure 8) may be configured to display gas concentration readings detected by the ultrasonic gas composition sensor system, such as oxygen concentration or one or more other gas concentration levels.

[0127] In some embodiments, the main controller is configured to determine whether one or more gas concentration levels, for example, oxygen concentration, remain within a user-defined range defined by a maximum threshold and / or minimum threshold. For example, in such embodiments, the main controller may be configured to compare the detected gas concentration level based on the gas concentration output signal 188 with a user-defined or selected gas concentration level threshold. If the detected level is below the minimum threshold, above the maximum threshold, or otherwise outside the user-defined range, the main controller may trigger or activate an alarm built into the device, which may be audible, visible, tactile, or any combination thereof. The main controller may also optionally shut down the device or trigger any other appropriate action function for each alarm that is triggered.

[0128] In some embodiments, the breathing apparatus 10 includes a disinfection system and / or cleaning mode of the type described in International Publication No. 2007 / 069922, which is incorporated by reference. Such a disinfection system utilizes thermal disinfection by circulating heated dry gas through a portion of the gas flow path to the user interface. In such embodiments, the main controller is configured to determine, based on the detected oxygen signal 188, whether the oxygen concentration level in the gas flow path is below a preset oxygen concentration level before initiating any disinfection system or cleaning mode. For example, the main controller may be configured to prevent the initiation of any cleaning mode until the detected oxygen concentration is within a safe range, preferably below about 30%, in order to minimize the risk of fire.

[0129] The oxygen signal 188 can be further used to automatically control the motor speed of the blower unit, thereby changing the gas flow rate and, consequently, altering or changing the oxygen concentration, or to stop the operation of the device if the oxygen concentration falls outside a preset upper or lower threshold. Alternatively, the user of the breathing apparatus can manually control the oxygen supply flow rate from a central gas source connected to the breathing apparatus based on real-time feedback from the displayed oxygen reading, without needing to estimate the oxygen concentration based on a printed reference table, thereby changing the oxygen concentration. In some embodiments, the breathing apparatus has a valve that automatically changes or alters the oxygen supply flow rate from the central gas source, thereby changing the oxygen concentration. The main controller can receive the oxygen signal 188 and adjust the oxygen valve accordingly until a predetermined value of the oxygen signal 188 corresponding to the desired oxygen concentration is reached.

[0130] Alternative ultrasonic gas composition sensor system configuration Referring to Figures 26A to 26E, various alternative configurations for ultrasonic transducers in a gas composition detection system that detects the speed of sound through a gas flow by transmitting and receiving cross-flow ultrasonic beams or pulses are described. Similar reference numerals represent similar components.

[0131] Referring to Figure 26A and Figures 19-25, the transducer configuration 200 of the above-described embodiment is schematically shown. As shown, this transducer configuration provides a configuration in which a pair of transducers 202, 204 facing each other from both sides of the sensing passage 206, with the airflow direction generally indicated by 208. In this configuration 200, each of the transducers 202, 204 is driven as either a dedicated transmitter or a dedicated receiver, thereby transmitting ultrasonic pulses 210 unidirectionally across the airflow from the transmitter transducer to the receiver transducer. As shown, the transducer pair is aligned with respect to the airflow direction 208 (i.e., upstream or downstream with no displacement from each other) and configured to transmit cross-flow pulses substantially perpendicular to the airflow direction.

[0132] Referring to Figure 26B, an alternative transducer configuration 220 is shown, in which a pair of transducers 222, 224 are provided opposite each other on either side of the sensing path, but each transducer can operate as both a transmitter and a receiver. That is, each transducer is an ultrasonic transmitter-receiver or transceiver. In this configuration, bidirectional ultrasonic pulses 226 can be transmitted between the transmitter pair 222 and 224. For example, pulses can be transmitted alternately back and forth between the transducers, or in any other order or pattern. Here again, the transducer pair is aligned with respect to the airflow direction and configured to transmit cross-flow pulses substantially perpendicular to the airflow direction.

[0133] Referring to Figure 26C, an alternative echo transducer configuration 230 is shown, in which the transmitter-receiver transducer pair is provided in the form of a single ultrasonic transmitter-receiver transducer 232, which is located on one side of the sensing path and is configured to transmit cross-flow acoustic pulses 236 across the sensing path 206 and to receive reflected pulses or echoes reflected from the opposite side of the sensing path.

[0134] Referring to Figure 26D, an alternative transducer configuration 240 is shown, in which the transmitter transducer 242 and receiver transducer 244 are displaced from each other with respect to the airflow path (i.e., one is upstream of the other) and are located on opposite sides of the sensing path. In Figure 26D, the receiver is upstream of the transmitter, but the reverse configuration is also possible. In this configuration, the transmitter 242 can either transmit a crossflow pulse directly to the receiver 244 across the sensing path 206, as shown by beam 246, or it can create a longer indirect path length by a reflection path involving at least two reflections, as shown by beam 248. As shown, in this displaced configuration, the acoustic pulse has a crossflow direction that is inclined and traverses the airflow path direction 208 rather than being substantially perpendicular to it. Although a unidirectional configuration is shown, it will be understood that transducers 242, 244 may alternatively be an ultrasonic transmitter-receiver, and bidirectional beam pulses may be transmitted between the transducers forward and backward (i.e., both upstream and downstream with respect to the airflow).

[0135] Referring to Figure 26E, an alternative transducer configuration 250 is shown, which is a modification of the configuration in Figure 26D, in which the transmitter 252 and receiver 254 are again displaced from each other in the airflow direction 208 but are located on the same side of the sensing path, so that the transmitted cross-flow pulse 256 has at least one reflection (or multiple reflections in the case of longer path lengths) from the opposite side of the sensing path 206. In other respects, the same alternative options as those described with reference to Figure 26D apply, including bidirectional operation and swapping of the positions of the transmitter and receiver.

[0136] Referring to Figures 27A to 27C, various further alternative configurations for ultrasonic transducers in gas composition detection systems that detect the speed of sound through a gas flow by transmitting and receiving ultrasonic beams or pulses along the flow are described. Similar reference numerals represent similar components.

[0137] Referring to Figure 27A, an alternative transducer configuration 260 is shown, in which there is a pair of transducers 262, 264 facing each other from opposite sides of the sensing passage 206, with the airflow direction or axis generally indicated by 208. In this configuration 260, each of the transducers 262, 264 is driven as either a dedicated transmitter or a dedicated receiver, thereby transmitting ultrasonic pulses 266 unidirectionally through a beampath between the transmitter and receiver, substantially aligned with or parallel to the gas flow axis 208 in the sensing passage 206. In the embodiment shown, the transmitter is upstream of the receiver, but it will be understood that the reverse configuration can also be used. In this configuration, a flow sensor is provided in the sensing passage to provide a flow signal indicating the flow rate of the gas flow in the sensing passage. It will also be possible to derive or determine the speed of sound in the sensing passage in the same manner as described above using the previous embodiment, and it will be understood that the flow signal is used in signal processing to remove or compensate for the gas flow rate with a calculated speed of sound signal.

[0138] Referring to Figure 27B, an alternative transducer configuration 270 is shown, in which a pair of transducers 272, 274 are provided facing each other from opposite sides of the sensing passage, similar to Figure 27A, but each transducer can operate as both a transmitter and a receiver. That is, each transducer is an ultrasonic transmitter-receiver or transceiver. In this configuration, bidirectional ultrasonic pulses 276 along the flow can be transmitted between the transducer pair 272 and 274. For example, the pulses can be transmitted alternately back and forth between the transducers, or in any other order or pattern. Here again, the transducer pair is aligned with respect to the airflow axis 208, substantially aligned with the airflow axis 208 in the sensing passage 206, or configured to transmit pulses along the flow in one or more parallel beam paths. When using this configuration, the flow component of the sound velocity signal can be directly derived or identified from the processing of the transmitted and received acoustic pulses, so a separate flow sensor is not necessarily required.

[0139] Referring to Figure 27C, an alternative echo transducer configuration 280 is shown, in which the transmitter-receiver transducer pair is provided in the form of a single ultrasonic transmitter-receiver transducer 282, which is located on one side of the sensing passage (whether at the start or end) and is substantially aligned with or parallel to the airflow axis 208, along the sensing passage 206, transmitting flow-following acoustic pulses 286 and receiving reflected pulses or echoes reflected from the opposite end of the sensing passage. In the shown embodiment, the transmitter-receiver 282 is shown at the end of the passage, but alternatively, it may be located at the start of the passage. As in the configuration of Figure 27A, a flow sensor is provided in the sensing passage so that the sound velocity calculation can compensate for the airflow component.

[0140] Using the alternative configurations shown in Figures 26B-26E and 27A-27C, the driver circuit, receiver circuit, and signal processing can be configured accordingly to detect the speed of sound in the detection path, and then, as described above, the gas composition is determined using the speed of sound.

[0141] Desirable features 1. A respiratory assistance device configured to provide a heated and humidified gas flow, comprising: a gas inlet configured to receive a gas supply; a blower unit configured to generate a pressurized gas flow from the gas supply; a humidifier unit configured to heat and humidify the pressurized gas flow; a gas outlet for the heated and humidified gas flow; a flow path for the gas flow passing through the respiratory device from the gas inlet through the blower unit and the humidifier unit to the gas outlet; and a sensor assembly provided in the flow path before the humidifier unit, comprising an ultrasonic gas composition sensor system for detecting one or more gas concentrations in the gas flow.

[0142] 2. The ultrasonic gas composition sensor system comprises a transceiver pair consisting of a transmitter and a receiver, the transceiver pair being operable to transmit cross-flow acoustic pulses from the transmitter to the receiver through a gas flow to detect the speed of sound in the gas flow near the sensor assembly, according to paragraph 1, a respiratory assistance device.

[0143] 3. A respiratory assist device according to paragraph 2, wherein the transmitter and receiver pair is arranged such that the acoustic pulses move along the gas flow in a direction substantially perpendicular to the direction of gas flow.

[0144] 4. A respiratory assist device according to paragraph 2, wherein the transmitter-receiver pair is arranged such that acoustic pulses move along the gas flow in a cross-flow that is inclined with respect to the direction of gas flow but is not perpendicular to it.

[0145] 5. A respiratory assistance device according to any one of paragraphs 2 to 4, comprising a transmitter-receiver pair comprising a transducer configured as a transmitter and a transducer configured as a receiver, which transmits unidirectional acoustic pulses.

[0146] 6. A respiratory assist device according to any one of paragraphs 2-4, comprising a transmitter-receiver pair comprising a pair of transmitter-receiver transducers configured to transmit bidirectional acoustic pulses.

[0147] 7. A respiratory assist device according to paragraph 5 or 6, wherein the transmitter and receiver are aligned with respect to the direction of gas flow and face each other across the flow path.

[0148] 8. A respiratory support device according to paragraph 5 or 6, wherein the transmitter and receiver are displaced from each other in the direction of gas flow.

[0149] 9. A respiratory assist device according to paragraph 8, in which acoustic pulses have a direct beam path between the transmitter and receiver.

[0150] 10. A respiratory assist device according to paragraph 8, wherein the acoustic pulse has a beam path that is indirect between the transmitter and receiver and undergoes one or more reflections.

[0151] 11. A respiratory assist device according to any one of paragraphs 2-4, wherein the pair of transmitter transducer and receiver transducer is a single transmitter-receiver configuration configured to transmit cross-flow acoustic pulses and receive echo return pulses.

[0152] 12. A respiratory assist device according to paragraph 2, comprising a pair of transmitter and receiver transducers that can operate to detect the speed of sound in the gas flow near a sensor assembly by transmitting flow-following acoustic pulses from the transmitter to the receiver through the gas flow.

[0153] 13. A respiratory assist device according to any one of paragraphs 2 to 12, further comprising a sensor control system configured to operate the transducer pair to detect the speed of sound through a gas flow and generate a sound velocity signal indicating the speed of sound, operably connected to a pair of transmitter and receiver transducers of an ultrasonic gas composition sensor system.

[0154] 14. A respiratory assist device according to paragraph 13, wherein the sensor control system is configured to generate one or more gas concentration signals indicating the gas concentration in the gas flow based on a signal indicating the speed of sound through the gas flow.

[0155] 15. A respiratory assist device according to paragraph 13 or 14, wherein the sensor assembly further comprises a temperature sensor configured to measure the temperature of the gas flow near the sensor assembly and generate a representative temperature signal, and the sensor control system is configured to generate one or more gas concentration signals indicating the gas concentration in the gas flow based on the sound velocity signal and the temperature signal.

[0156] 16. A respiratory assist device according to paragraph 13 or 14, wherein the sensor assembly further comprises a humidity sensor configured to measure the humidity in a gas flow near the sensor assembly and generate a representative humidity signal, and the sensor control system is configured to generate one or more gas concentration signals indicating the gas concentration in the gas flow based on the sound velocity signal and the humidity signal.

[0157] 17. A respiratory assist device according to paragraph 13 or 14, wherein the sensor assembly further comprises a temperature sensor configured to measure the temperature of a gas flow near the sensor assembly and generate a representative temperature sensor, and a humidity sensor configured to measure the humidity in the gas flow near the sensor assembly and generate a representative humidity signal, and the sensor control system is configured to generate one or more gas concentration signals indicating the gas concentration in the gas flow based on the sound velocity signal, the temperature signal, and the humidity signal.

[0158] 18. A respiratory assist device according to paragraph 15 or 17, wherein the sensor control system is configured to apply temperature compensation to the temperature signal to compensate for any predicted temperature sensing errors caused by heat within the respiratory device that affect the temperature sensor.

[0159] 19. The respiratory assist device according to paragraph 18, wherein the sensor assembly further comprises a flow sensor configured to detect the flow rate of the gas flow near the sensor assembly and generate a representative flow signal, and the system further comprises a motor speed sensor configured to detect the motor speed of the blower unit and generate a representative motor speed signal, and temperature compensation is calculated by the sensor control system based on at least the flow signal and / or the motor speed signal.

[0160] 20. A respiratory support device according to any one of paragraphs 13-19, wherein the sensor control system is configured to generate a gas concentration signal representing the oxygen concentration in the gas stream.

[0161] 21. A respiratory support device according to any one of paragraphs 13-19, wherein the sensor control system is configured to generate a gas concentration signal representing the carbon dioxide concentration in the gas stream.

[0162] 22. A respiratory assistance device according to any one of paragraphs 1 to 21, wherein the sensor assembly is detachably mounted within the flow path.

[0163] 23. A respiratory assist device according to any one of paragraphs 1 to 22, wherein the flow path has a shape or configuration that facilitates a stable flow of gas in at least one section or portion of the flow path.

[0164] 24. A respiratory assist device according to paragraph 23, wherein the flow path has a shape or configuration that facilitates a stable flow in a section or portion of the flow path, including a sensor assembly.

[0165] 25. A respiratory support device according to paragraph 23 or 24, wherein the flow path comprises one or more flow directors at or toward the gas inlet.

[0166] 26. Each flow director is in the form of a bow-shaped fin, an assisted breathing device according to paragraph 25.

[0167] 27. A respiratory assist device according to any one of paragraphs 23 to 26, wherein the flow path comprises at least one helical portion or section that facilitates a stable flow of gas.

[0168] 28. A respiratory assist device according to paragraph 27, wherein the flow path comprises an inlet section extending between a gas inlet and a blower unit, the inlet section comprising at least one helical section.

[0169] 29. A respiratory assistance device according to paragraph 27 or 28, wherein the sensor assembly is positioned in the helical portion of the flow path.

[0170] 30. A respiratory assist device according to paragraph 29, wherein the spiral section comprises one or more substantially straight sections, and the sensor assembly is positioned in one of the straight sections.

[0171] 31. A respiratory assist device according to any one of paragraphs 2 to 30, wherein the sensor assembly comprises a sensor housing having a main body, the main body being hollow and defined by a peripheral wall extending between a first open end and a second open end, thereby defining a detection passage between the walls within the main body, through which a gas flow can flow in the direction of a flow axis extending between the first end and the second end of the main body, and a pair of transmitter transducers and receiver transducers are arranged on opposite walls or sides of the detection passage.

[0172] 32. A respiratory assistance device according to paragraph 31, comprising: a sensor housing comprising a main body having two spaced-apart side walls and an upper and lower wall extending between the side walls, defining a detection passage along the main body between a first end and a second end; and a pair of transducer mounting assemblies disposed on opposing walls of the main body, each of which is configured to receive and hold each transducer of the transducer pair so that each transducer of the transducer pair is aligned and faces each other across the detection passage of the main body.

[0173] 33. A respiratory support device according to any one of paragraphs 1 to 32, wherein the blower unit is operable to generate a gas flow at the gas outlet having a maximum flow rate of 100 liters / minute.

[0174] 34. A respiratory assist device according to any one of paragraphs 1 to 33, wherein the gas inlet is configured to receive a supply of gas containing a mixture of atmospheric air and pure oxygen from an oxygen source.

[0175] 35. A respiratory assist device according to any one of paragraphs 1 to 33, wherein the gas inlet is configured to receive a supply of gas containing a mixture of atmospheric air and carbon dioxide from a carbon dioxide source.

[0176] 36. A respiratory support device according to any one of paragraphs 1 to 35, wherein the flow path is located within the bulk flow path of the device.

[0177] 37. A sensor assembly for detecting an inline flow path of gas flow in a respiratory support device, comprising a sensor housing having a main body, the main body being hollow and defined by a peripheral wall extending between a first open end and a second open end, thereby defining a detection passage between the walls within the main body, through which the gas flow can flow in the direction of a flow axis extending between the first end and the second end of the main body, the sensor assembly comprising an ultrasonic gas composition sensor system mounted on the sensor housing for detecting one or more gas concentrations in the gas flow flowing through the detection passage, a temperature sensor mounted on the sensor housing for detecting the temperature of the gas flow flowing through the detection passage, and a flow sensor mounted on the sensor housing for detecting the flow rate of the gas flow flowing through the detection passage.

[0178] 38. The sensor housing is configured to detachably engage with a complementary retaining aperture in the flow path of the respiratory assistance device, as per paragraph 37.

[0179] 39. An ultrasonic gas composition sensor system comprising a sensor assembly according to paragraph 37 or 38, comprising a pair of transmitter and receiver transducers operable to transmit acoustic pulses from a transmitter to a receiver through a gas flow in a direction substantially perpendicular to the flow axis of the gas flow flowing through a sensing passage.

[0180] 40. A pair of transmitter transducers and receiver transducers are arranged in a sensor assembly according to paragraph 39, on opposite walls or sides of the sensing passage.

[0181] 41. A sensor assembly according to paragraph 39 or 40, comprising a sensor housing body having two spaced-apart side walls and an upper and lower wall extending between the side walls, defining a sensing passage along the body between a first end and a second end, the body comprising a pair of transducer mounting assemblies positioned on opposing walls of the body, each of the pair of transducer mounting assemblies configured to receive and hold each transducer of the transducer pair so that each transducer of the transducer pair is aligned and facing each other across the sensing passage of the body.

[0182] 42. A pair of transducer-mounted assemblies are arranged on opposing side walls of the main body, and each transducer-mounted assembly has a holding cavity that internally receives and holds each transducer of the pair, forming a sensor assembly according to paragraph 41.

[0183] 43. Each transducer-mounted assembly comprises a cylindrical base portion extending from each side wall of the main body and at least one pair of opposing clips extending from the base portion, the base portion and the clips together define a holding cavity, the sensor assembly according to paragraph 42.

[0184] 44. Each side wall of the main body is provided with a transducer aperture, the transducer aperture is aligned with the associated transducer-mounted assembly, and the operating front of the transducer extends through the transducer aperture to access the sensing passage, the sensor assembly according to paragraph 43.

[0185] 45. A sensor assembly according to paragraph 44, wherein the transducer assembly is configured such that the working surface of each transducer is in substantially the same plane as the inner surface of each wall of the main body of the sensor housing.

[0186] The above description of the present invention includes preferred embodiments of the invention. Modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A respiratory support device configured to provide a heated and humidified gas stream containing a two-component gas mixture of atmospheric air and supplemented nitrogen, The main enclosure, One or more gas inlets configured to receive atmospheric air, A supplemental gas connection inlet is configured to receive a supply of nitrogen from a supplemental gas source in order to mix with the atmospheric air to generate a gas flow containing the two-component gas mixture, A blower unit configured to pressurize the gas flow, A humidification unit configured to heat and humidify the gas flow, A gas outlet for the gas flow, following the blower unit and the humidifier unit, A gas flow path through the main housing, from the gas inlet through the blower unit and the humidifier unit to the gas outlet, wherein the flow path within the main housing comprises an inlet section extending between the gas inlet and the blower unit, and the inlet section comprises at least one spiral section provided upstream of the blower unit for facilitating a stable flow of the gas flow within the flow path for detection by a sensor assembly, The sensor assembly is provided in the inlet section of the flow path within the main housing, upstream of the blower unit and the humidifier unit, for the purpose of detecting a stable flow of the gas flow, and the sensor assembly includes an ultrasonic gas composition sensor system for detecting one or more gas concentrations in the gas flow. A sensor control system operably connected to the sensor assembly and generating one or more gas concentration signals representing the one or more gas concentrations in the gas flow, A main housing comprising, A respiratory support device in which the one or more gas concentration signals include gas concentration signals representing the detected nitrogen concentration in the gas stream.

2. The respiratory assist device according to claim 1, further comprising an output display configured to display one or more gas concentration levels based on the one or more gas concentration signals.

3. The respiratory assist device according to claim 1 or 2, wherein the main controller of the device is configured to compare one or more detected gas concentration levels, represented by one or more gas concentration signals, with each user-defined range defined by a maximum threshold and / or a minimum threshold, and further configured to trigger or activate an alarm of the device if the detected level is less than the minimum threshold, greater than the maximum threshold, or otherwise outside the user-defined range.

4. The respiratory assist device according to any one of claims 1 to 3, wherein the ultrasonic gas composition sensor system comprises a pair of transmitter transducers and receiver transducers, the sensor control system is operably connected to the pair of transmitter transducers and receiver transducers and configured to operate the pair of transducers to generate a sound velocity signal indicating the speed of sound through the gas flow, and is configured to generate one or more gas concentration signals indicating one or more gas concentrations in the gas flow based on at least the signal indicating the speed of sound through the gas flow.

5. The respiratory assistance device according to claim 4, wherein the pair of transmitter-receiver transducers is operable to transmit cross-flow acoustic pulses from the transmitter to the receiver through the gas flow in order to detect the speed of sound in the gas flow near the sensor assembly.

6. The respiratory assistance device according to claim 4, wherein the pair of transmitter transducer and receiver transducer is operable to transmit flow-oriented acoustic pulses from the transmitter to the receiver through the gas flow in order to detect the speed of sound in the gas flow near the sensor assembly.

7. The respiratory assist device according to claim 4, wherein the sensor assembly further comprises a temperature sensor configured to measure the temperature of the gas flow near the sensor assembly and generate a representative temperature signal, and the sensor control system is configured to generate one or more gas concentration signals indicating one or more gas concentrations in the gas flow based on the sound velocity signal and the temperature signal.

8. The respiratory assistance device according to claim 4, wherein the sensor assembly further comprises a humidity sensor configured to measure the humidity of the gas flow near the sensor assembly and generate a representative humidity signal, and the sensor control system is configured to generate one or more gas concentration signals indicating one or more gas concentrations in the gas flow based on the sound velocity signal and the humidity signal.

9. The respiratory assistance device according to any one of claims 1 to 8, wherein the sensor assembly further comprises a flow sensor configured to detect the flow rate of the gas flow in the vicinity of the sensor assembly and generate a representative flow rate signal.

10. The respiratory assistance device according to claim 9, wherein the flow sensor comprises a hot-wire anemometer flow detector.

11. The respiratory support device according to any one of claims 1 to 10, wherein the humidifying unit further comprises a heater plate.

12. The respiratory support device according to any one of claims 1 to 11, wherein the humidifying unit further comprises a humidifying water chamber.

13. The gas flow path through the main housing, Most of the inflow section of the flow path in front of the blower unit, The flow path between the blower unit and the humidifier unit, and / or The flow path after the humidification unit, A respiratory support device according to any one of claims 1 to 12, wherein one or more of the components are sealed.

14. The respiratory assistance device according to any one of claims 1 to 13, wherein the humidifying unit comprises a humidifying unit compartment having a heater plate and receiving a humidifying water chamber, and the main housing of the device surrounds the blower unit and provides the humidifying unit compartment that receives the humidifying water chamber.

15. The respiratory assistance device according to any one of claims 1 to 14, wherein the sensor assembly is removably mounted in the flow path.

16. The respiratory support device according to any one of claims 1 to 15, wherein the supplemental gas connection inlet is connected to a nitrogen supply source to receive a supply of nitrogen.

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