Defogging of self-contained breathing system visor

Abstract

A mask assembly is provided for a breathing system. The assembly includes a full-face mask with a visor and a breathing hose that extends to a breathing hose connector to supply breathing gas. A defogging tube mns within the hose from the connector to the mask and is configured to deliver pressurized gas to one or more nozzles oriented to spray the gas onto the visor's inner surface. The connector includes an inner fitting attached to both the breathing hose and defogging tube, and an outer fitting configured to connect to a breathing gas outlet and to receive pressurized gas from a separate source via a pressurized gas port. The inner and outer fittings include, respectively, an outer surface groove and an inner surface groove that, when joined, form a channel configured to convey the pressurized gas from the port to the defogging tube.

Description

DEFOGGING OF SELF-CONTAINED BREATHING SYSTEM VISORFIELD OF THE INVENTION

[0001] The present invention relates generally to the field of self-contained breathing systems (SCBSs).BACKGROUND

[0002] Self-contained breathing systems are designed to be worn by those who work in conditions with insufficient oxygen or with hazardous levels of toxic gases. Typical users include first responders in environments immediately dangerous to life or health (IDLH), such as smoke-filled, toxic and / or generally bad-air environments, in which the atmosphere is unsuitable for breathing. Breathing systems for such applications include closed-circuit, semi-closed, and open-circuit systems.

[0003] Open-circuit breathing systems are those in which exhaled or expired gases are discharged into the atmosphere and not rebreathed. Although such open-circuit systems are simple and provide excellent protection to the user, the high rate of gas usage, and the resulting weight and size of the required gas cylinder, typically limit the usage duration of such systems to about 30 to 45 minutes.

[0004] In semi-closed circuits, some exhaled air is released, while some is maintained in a rebreathing circuit, to which fresh air from a gas cylinder is added. By contrast, in closed- circuit breathing systems, also known as closed-circuit rebreathers (CCRs), the exhaled gas is passed through a carbon dioxide (CO2) chemical scrubber and combined with fresh oxygen from a gas cylinder to maintain oxygen content at a life-supporting level. An example of a CCR is described in International Patent Application PCT / IL2024 / 050035 to the inventors of the present invention, incorporated herein by reference.

[0005] A common issue encountered with such breathing systems is the fogging of the mask's visor, which impairs vision and compromises safety and operational efficacy.

[0006] Breathing systems may use a partial mask, in which only the nose and mouth are covered. Such partial masks provide a balance between comfort and protection, and are suitable for oxygen-deficient environments. Such partial masks eliminate the issue of fogging because they have no visor, but they do not provide sufficient protection for the user’s eyes and face in chemical, biological, radioactive, and nuclear (CBRN) environments that contain contaminants and / or agents that may hurt the eyes. Toxic environments, including smoky environments, such as a fire zone, may be harmful to soft tissues like the eyes. Consequently, many breathing systems use full-face masks that offer complete facial protection against airborne contaminants as well as a secure seal for efficient gas circulation. However, these masks suffer from visor fogging due to the humidity exhaled from the user’s lungs during breathing, which then condensates on the surface of the visor.

[0007] Various attempts have been made to solve the fogging problem. Two common approaches are antifogging and defogging. Antifogging can be done passively, e.g., by applying an anti-fog agent on the mask’s interior visor to minimize the surface tension of the water. Such anti-fog agents include surfactants like ethoxylates, polysiloxanes, and various detergents. However, these agents provide a very short period of anti-fogging capabilities and do not last for long. Antifogging can also be done by heating the visor, either passively by coating the visor with transparent gold nanocoating that harnesses sunlight to heat the visor lenses, or actively by using a power source to heat the visor lenses as done in the car’s rear and front windshields or in aircraft / cockpit windows. However, the first requires sunlight and is ineffective during dark or when there is no sunlight, and the other is a big energy consumer that requires a large battery and moreover may be dangerous when utilized in a 100% oxygen environment as used in a CCR.

[0008] US 2022 / 0088420 and US 2021 / 0368885 describe vent systems for defogging a visor of a user’s mask using dedicated vents. US 11,071,881 describes a visor device with a controlled airflow to prevent fogging of the visor. CN 212788860U describes anti-fog goggles having an airflow distributor. CA 3002065 describes a helmet having a ventilation system to prevent deposition of fog on the visor.

[0009] US Patent 4,534,344 describes a facemask for closed-circuit breathing apparatus featuring a dual-mask system, with an outer mask sealing over the eyes and a separate inner mask for the mouth and nose. Oxygen is supplied to the outer mask to demist the visor before it passes through a one-way valve into the inner mask to be added to recirculated gas inhaled by the wearer. The oxygen is delivered through a supply pipe 21, which runs inside a stub pipe 15 of the recirculated gas supply. (A method for connecting an oxygen cylinder to the supply pipe 21 in the stub pipe is not described.)

[0010] Each of the above systems suffers from its own disadvantages. These, as well as the disadvantages of the prior art antifogging and defogging techniques, are overcome by the present defogging system and method.SUMMARY

[0011] The present invention provides a mask assembly for a breathing system, including a full-face mask, configured to defog a visor of the full-face mask. A breathing hose of the mask assembly connects, at one end, to a mouthpiece of the full-face mask and has, at its other end, a breathing hose connector configured to connect to a breathing gas port of the breathing system. The breathing gas port provides breathing gas (i.e., breathable gas) that may include a portion of previously exhaled air. In addition, the hose connector has a pressurized gas port receiving pressurized gas for defogging of the visor. The pressurized gas typically is gas that has not been previously exhaled. A defogging tube extends from apressurized gas port through the mouthpiece of the mask to one or more nozzles inside the mask, where the nozzles are oriented to spray the pressurized gas (“defogging gas”) towards the inner surface of the visor to remove condensate from the visor.

[0012] The pressurized gas port may be included in the breathing hose connector, whereby the breathing hose connector isolates the pressurized gas from the breathing gas. The breathing hose connector may be a quick release connector, having complementary inner and outer fittings, whereby disconnection of the fittings disconnects the mask from both the breathing gas and from the pressurized gas for defogging. The inner fitting is attached both to the breathing hose and to the defogging tube and connects into the outer fitting. The outer fitting connects to a breathing gas outlet of the breathing system to receive the breathing gas and also has a pressurized gas port to receive the pressurized gas from a pressurized gas source that is separate from the breathing gas outlet. An outer surface groove of the inner fitting and an inner surface groove of the outer fitting, when joined, form a channel to direct the flow of the pressurized gas from the pressurized gas port to a pressurized gas passage in the inner fitting, which connects to the defogging tube.

[0013] The pressurized gas may be dry gas, that is, gas containing no moisture, such as oxygen provided by a gas cylinder to provide a user of the breathing system with a sufficient level of oxygen.

[0014] The present invention also provides a method for defogging a visor of a full-face mask of a breathing system, the method including: (a) providing a mask assembly having a full-face mask and a breathing hose; (b) connecting the full-face mask to the breathing hose; and (c) releasing pressurized gas through a defogging tube to be sprayed by nozzles in the mask over the visor and defogging thereof.

[0015] In a further aspect of the present invention, a method and system are provided for defogging a visor of a vision system by directing nozzles spraying pressurized gas towards the inner surface of the visor.

[0016] In a further aspect of the present invention, a breathing system is provided including: (a) a compressed gas cylinder; (b) a gas regulator attached to said cylinder and designed to provide gas at a regulated pressure; and (c) a mask configured to be worn by a user, the mask including a visor, and connected by a defogging tube to an outlet of said gas regulator, wherein said mask includes one or more nozzles oriented to deliver the gas from the regulator onto the visor for defogging thereof.

[0017] In a further aspect, the present invention provides a closed-circuit rebreather (CCR) system including: (a) a cylinder of compressed gas; (b) a gas regulator attached to said cylinder and designed to provide gas at a regulated pressure; (c) a carbon dioxide (CO2) absorber with CO2 scrubber material; (d) a counterlung connected to said CO2 absorber and designed to receive previously exhaled air exiting the CO2 absorber; and (e) a mask configured to be worn by a user, the mask including a visor, and connected to said counterlung via a breathing hose to receive the previously exhaled air, wherein said mask further includes a manifold connected to a defogging tube extending from the gas regulator designed to deliver pressurized gas to nozzles within the mask for spraying the pressurized gas onto the visor for defogging thereof. The pressurized gas delivered to the nozzles may be dry gas. The pressurized gas delivered to the nozzles also may be, for at least a period of operation of the breathing system, the only source of oxygen added to the previously exhaled, to maintain a sufficient level of oxygen for a user of the CCR system.

[0018] In a further aspect, the present provides a system for defogging a mask's visor in a breathing system, including: a mask with a visor configured to be worn by a user; a compressed gas cylinder; one or more nozzles within the mask configured to direct gas ontothe inner surface of the visor to maintain clear vision by reducing condensate formation on the visor’s surface; and a conduit providing a passageway for the gas from the compressed gas cylinder to the nozzles within the mask.BRIEF DESCRIPTION OF DRAWINGS

[0019] For a better understanding of various embodiments of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, as follows.

[0020] Figs. 1A-1B show elements of a breathing system including elements for defogging a mask visor, according to some embodiments of the present invention.

[0021] Figs. 2A-2B are additional views of the breathing system showing additional system elements, according to some embodiments of the present invention.

[0022] Fig. 3 is a block diagram of the breathing system, according to some embodiments of the present invention.

[0023] Figs. 4-5 are illustrations of a full-face mask of the breathing system showing the full-face mask, with the defogging tube entering the mask through the mouthpiece, according to some embodiments of the present invention.

[0024] Fig. 6 is an illustration of a full-face mask of the breathing system, with the defogging tube entering the mask through a dedicated port other than the mouthpiece, according to some embodiments of the present invention.

[0025] Figs. 7A-7B are illustrations of the breathing hose with the defogging tube extending within the breathing hose, according to a specific embodiment of the invention.

[0026] Fig. 8 is an illustration of the breathing hose and the defogging tube entering the mask separately, according to a specific embodiment of the invention.

[0027] Fig. 9 shows cut-away illustrations of the inner and outer fittings of the breathing hose connector, according to some embodiments of the present invention.

[0028] Figs. 10A-10C are further views of the inner and outer fittings of the breathing hose connector, according to some embodiments of the present invention.

[0029] Figs. 11A-11B are illustrations of a spray nozzle, according to a specific embodiment of the invention.

[0030] Figs. 12A-12D illustrate a manifold configured to be positioned inside the mask, opposite the mask mouthpiece, to receive pressurized gas from the defogging tube and distribute the gas to separate conduits inside the mask, each of which connect to nozzles that spray gas.DETAILED DESCRIPTION

[0031] Embodiments of the present invention provide systems and methods for defogging a visor of a mask of a breathing system. The invention includes controlling a defogging process by directing gas flow towards the inner surface of a visor, especially dry gas, thereby enhancing visibility by removing condensation effectively. The removal of condensation enhances user safety, operational performance, and comfort.

[0032] The invention is described by reference to the accompanying drawings, which are to be considered only as representative examples of embodiments of the invention. Alterations and modifications may be made by those having ordinary skill in the art without departing from the scope of the invention. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purpose of example and that it should not be taken as limiting the invention and its various embodiments and / or by the following claims. A teaching that two elements are combined in a claimed combination is further to be understood as also allowing for a claimed combination in which the two elements are notcombined with each other, but may be used alone or combined in other combinations. The excision of any disclosed element of the invention is explicitly contemplated as within the scope of the invention.

[0033] Fig. 1A shows a mask assembly (20) of a breathing system including a full5face mask (22) and elements for defogging a mask visor (24). Shown in the figure is a closed- circuit rebreather (CCR) configuration, but the principals of the present invention may also be applied to open-circuit breathing systems and to other types of systems with full-face masks having visors that may become fogged by condensation.

[0034] A mouthpiece (32) of the mask assembly receives “breathing gas” from a breathing hose (34), which may be dedicated to inhalation, such that the system also includes an exhalation hose (36). The mouthpiece may also regulate inhalation of breathing gas from the breathing hose (34) and exhalation of air to the exhalation hose (36). The distal end of the breathing hose has a breathing hose connector (38) connecting the breathing hose to breathing air from the breathing system, which, as described below, may be provided by a counterlung (i.e., gas reservoir). Hereinbelow, the terms “air” and “breathing air” refer to any combination of breathable air including sufficient oxygen to support life.

[0035] The breathing hose connector (38) may be, for example, a two-part, swivel connector, having an inner fitting (38 A) fixed to the breathing hose, and an outer fitting (38B), fixed to an outlet of the counterlung. The two parts may be connected with a fastener (40), which is typically a quick-release fastener. The fastener ensures that the inner and outer fittings are securely attached, for effective respiratory management, while enabling easy and fast disconnection when needed.

[0036] The breathing gas conveyed by the breathing hose (34) may be decompressed gas from a gas cylinder (e.g., for an open-circuit breathing system) and / or recycled air from a rebreather. The breathing hose extends from the breathing hose connector (38) to themouthpiece (32). In the example indicated in the figure, breathing gas passes into the breathing hose through the outer fitting’s main inlet (42).

[0037] A tube referred to herein as a defogging tube (44) may receive pressurized gas from a pressurized gas port (46) external to the mask, to convey the gas into the mask for defogging the mask visor (24). The defogging tube (44) conveys the pressurized gas (also referred to herein as “defogging gas) may pass within the breathing hose through the mouthpiece (32), or through an alternative mask entrance, to a manifold (48). The manifold in turn distributes the pressurized gas to one or more nozzles (50) that spray the pressurized gas towards the mask visor (24), thereby removing condensate from the visor. Hereinbelow, the term “pressurized gas” with respect to the gas provided to the nozzles refers to gas that is at a sufficient pressure to cause a discernable flow of gas from the nozzles, which may be, by way of example, a level of pressure comparable to the pressure of air that is blown through a fan or pump.

[0038] The mask visor is subject to fogging due to moisture in human breath. The breathing gas, which for CCRs may also be gas that has been exhaled, also may include some moisture. The pressurized gas conveyed by the defogging tube may be any type of breathable gas, but is typically “dry gas” containing not moisture, such as pure oxygen, to further improve the defogging process performed by the spraying of the gas onto the visor.

[0039] Fig. IB shows the breathing hose (34) and the exhaust hose (36) of the mask assembly, both attached to the mouthpiece (32) described above. The distal end of the breathing hose is shown connected to a counterlung (62). A frame (64) is provided on which additional elements of the system are mounted. The frame is attached to a backpack harness (66). The frame may be designed to be removable from the backpack harness and from the breathing hose (34) and the exhaust hose (36) of the mask assembly, so that the frame and itscomponents, such as the gas cylinder, can be replaced while a user continues to wear the backpack harness and the mask assembly.

[0040] Figs. 2A-2B are additional views of elements of the breathing system. Fig. 2A shows the frame (64) without the harness, showing the outer fitting (38B) of the breathing hose connected to the counterlung (62). Fig. 2B shows the breathing system with the counterlung removed, showing a compressed gas cylinder (70) providing breathing gas, such as oxygen, and a CO2 absorber (72) (i.e., “scrubber”), which receives the exhaled air from the exhalation hose (36). Also shown are a counterlung outlet (74) (“breathing gas outlet”), which connects to the breathing hose inner fitting connector (38 A) by means of the outer fitting connector (38B). The counterlung may receive the scrubbed gas at a counterlung inlet (76). In typical configurations for land use, the gas cylinder contains medical grade oxygen, but other gas configurations may be used.

[0041] Also shown is a gas regulator (80), which adjusts the pressure of the compressed gas, and which may provide pressurized gas to the defogging tube. As described below, the regulator may be configured with two regulator stages so as to provide gas at a first, typically higher pressure for defogging and at a second, typically lower pressure to support counterlung “demand” flow, that is, flow that is determined by a user’s breathing rate, as described below.

[0042] Fig. 3 is a block diagram of the elements described above assembled as a breathing system (60), showing schematically the flows of gas through a rebreather system.

[0043] The gas regulator (80) may include multiple stages. A first stage regulator (82) of the gas regulator (80) may decompress gas from the compressed gas cylinder (70) to a pressure level above atmospheric pressure. This “pressurized gas,” indicated by a hashed line in the figure, flows to the defogging tube (44), which may pass within the breathing hose (34), isolated from the breathing gas conveyed in the breathing hose. A typical range ofpressure from the first stage regulator may be 5 to 10 bar, which may be provided at a “free flow” gas rate that is not dependent on user’s breathing demand, or which may be variable, dependent on user demand or defogging need. The rate of flow may be in a range of, for example, 0.5 to 2.5 liters / minute. As described above, the defogging tube may convey the pressurized gas through the mouthpiece of the mask to reach the nozzles (50), which spray the pressurized gas towards the visor, thereby defogging the visor.

[0044] “Breathing gas,” indicated in the figure as a solid line, may flow from the counterlung (62) through the breathing hose connector (38) to the breathing hose (34), to reach the mouthpiece (32) of the full-face mask (22). As described above, the flow of gas from the counterlung is “demand flow”: when a user breaths at a higher rate, more of the demand gas is inhaled from the counterlung, and this demand flow may be supported by a second stage regulator (84).

[0045] In a closed-circuit system, such as the one shown, the breathing gas, when exhaled (i.e., “exhaled gas”), flows through the exhalation hose (36) to the CO2 absorber (i.e., scrubber) (72), from which the breathing gas then returns to the counterlung. A normal resting ventilation of 6 liters per minute (L / min) results from a rate of 12 breaths per minute and a tidal volume (i.e., volume per breath) of 0.5 liters. During moderate effort, ventilation increases to 30 to 50 L / min, and may reach 120 L / min at maximal exertion. (In an opencircuit breathing system, the exhaled gas is simply expelled.)

[0046] In general, breathing systems may be configured such that, if the counterlung pressure drops, additional “demand” gas may be provided by the second stage regulator (84) to the counterlung, typically provided at approximately atmospheric pressure. In some embodiments, the pressurized gas flow of the defogging tube may be set sufficiently high so that additional demand gas may not be needed, at least for low exertion activity by a user.That is, in some embodiments the level of oxygen provided for defogging obviates the need to provide additional oxygen at other points in the rebreather cycle.

[0047] The rate of the pressurized gas flow directed towards the visor may also be controlled by automatic (i.e., electronically or electrically) or manual control. Accordingly, in specific embodiments of the system according to any of the embodiments above, a valve or controller (86) may control the flow of gas, wherein said valve is either manual or may be automatically controlled based on, for example, signals from one more mask sensors (88). Such mask sensors may include, for example, a humidity sensor, a pressure sensor, and / or a vision sensor (identifying that vision is impaired by visor condensation), or any other suitable sensor or combination of sensors. The sensors may be configured to trigger an increase in gas flow when fogging is detected or when detected humidity exceeds a predefined threshold. In specific embodiments, the valve is a manual override switch designed to allow the user to control the defogging. In further specific embodiments, the manual override is operable to activate or deactivate the nozzles. In alternative certain embodiments, the flow of gas through the defogging tube (44) and nozzles (50) is constant (“free flow”) and is independent of the user’s breathing volume and rate. The valve, if present, may be positioned along any part of the path (i.e., “conduit”) from the regulator to the nozzles, or integrated with any element along the path, such as with gas regulator, the hose connector, the defogging tube, the manifold, or the nozzles.

[0048] Gases suitable for use in the defogging system according to any of the embodiments above typically possess certain characteristics, such as dryness and nonreactivity, which help to remove condensate from the visor without causing harm to the user or degradation of the system components. Some examples of gases that can be used in the defogging system alone or in various compositions include the gases in the following list.Oxygen can be provided for both the defogging gas and the breathing gas, or may be mixed with other gases.• Nitrogen is a dry gas that does not react easily with other substances, making it an appropriate gas for use in a breathing environment.• Argon is an inert gas that provides similar benefits to nitrogen but may be used in scenarios requiring denser gas compositions to aid in the defogging process.• “Dry air” composed primarily of nitrogen and oxygen can be specially processed to remove moisture, making it another suitable choice for defogging.• Carbon dioxide when used in small quantities can assist in displacing humidity on a visor, though its concentration levels must be carefully controlled to maintain a safe breathing environment.• Helium has a low density and non-reactive nature, and can be mixed with other gases to achieve specific defogging performance characteristics while ensuring safety and comfort for the user.

[0049] Each of these gases offers specific advantages and may be selected based on the requirements of the defogging system, environmental conditions, and safety considerations. The selection of the appropriate gas must align with the overall design and operational parameters of the breathing system.

[0050] It is to be noted that the defogging tube, the nozzles, and the pressurized gas source of the present invention are referred to above as a "defogging system," designed to reduce condensation of moisture on surfaces, such as glass or transparent polymer materials, which may include but are not limited to face masks, vehicle windows, mirrors, lenses, etc. In further embodiments, the defogging system may also be configured to manage thetemperature of the surface to be defogged and / or the humidity of the air in proximity to the surface.

[0051] Figs. 4-5 are illustrations of a full-face mask of the breathing system showing the full-face mask (22) equipped with multiple spray nozzles (50), with the defogging tube entering the mask through the mouthpiece. The nozzles are engineered to distribute gas directly onto the inner surface of the visor, to provide efficient defogging. The nozzles receive the pressurized gas (“defogging gas”) from the manifold (48), which distributes the pressurized gas to the nozzles through manifold extension tubes (96). Fig. 4 is a perspective view, while Fig. 5 is a side view of the full-face mask (22), also showing the multiple spray nozzles (50), the manifold (48), the manifold extension tubes (96), the sensor (88), e.g., humidity or visibility sensor, as well as the visor (24). A nozzle located to the side of the visor, approximately at the level of a user’s eyes, is distinguished in the figure as nozzle 50A. Through tests, this location has been shown to be particularly efficient for removing condensation on the visor.

[0052] Fig. 6 is an illustration of a full-face mask of the breathing system showing the full-face mask (22) equipped with multiple spray nozzles (50), with the defogging tube entering the mask through the side of the mask, in an alternative configuration.

[0053] Figs. 7A-7B are illustrations of the breathing hose (34) and the defogging tube (44) extending within the breathing hose, corresponding to the example of the full face mask described above with respect to Figs. 4-5. In Fig. 7A, the breathing hose is shown with the pressurized gas for the defogging tube (44) entering the breathing hose at the pressurized gas port (46) of the outer fitting hose connector (38) and exiting through the mouthpiece (to enter into the mask). Fig. 7B shows the defogging tube (44) entering the breathing hose at the side of the hose and exiting through the mouthpiece (in an alternative configuration).

[0054] Fig. 8 is an illustration of the breathing hose (34) and the defogging tube (44) entering the mask through separate ports, corresponding to the example of the full face mask described above with respect to Fig. 6. However, as in the example of Fig. 7A, pressurized gas for the defogging tube (44) entering the breathing hose at the pressurized gas port (46) of the outer fitting hose connector (38).

[0055] Fig. 9 shows cut-away illustrations of the inner and outer fittings of the hose connector, positioned with the inner fitting above the outer fitting (i.e., before connection). The cut-away of the inner fitting (38 A) shows an outer surface groove (90 A) of the connection that forms an inner side of a pressurized gas channel that transfer pressurized gas from the outer fitting (38B) to a pressurized gas passage (92) of the inner fitting. The passage (92) leads to a passage tube connector (94) that connects to the defogging tube. The outer fitting (38B) is shown likewise with an inner surface groove (90B) extending from the pressurized gas port (46), which, when joined with the outer surface groove forms the pressurized gas channel.

[0056] Figs. 10A-10C show further views of the inner and outer fittings of the breathing hose connector, when the fittings are disconnected from each other. The pressurized gas enters the pressurized gas port (46), which conveys the gas through a passage in the outer fitting shell to the pressurized gas channel, which runs between the outer surface of the inner fitting and the inner surface of the outer fitting when the inner and outer fitting grooves (90A and 90B) are joined. In other words, the connector channel is shared between the inner and outer fittings. Fig. 10C shows the inner fitting, with the outer surface groove (90A) of the connector channel. When the inner and outer fittings are joined, pressurized gas entering at the port (46) of the outer fitting flows into the connector channel between the grooves of the inner and outer fittings (90A and 90B). The pressurized gas flows from the connector channel through the pressurized gas passage (92) into the passage tube connector (94) describedabove, which connects to the defogging tube. Because both the breathing gas and the pressurized gas are connected to the outer fitting of the breathing gas connector, disconnecting the inner and outer fittings disconnects both the pressurized gas and the breathing gas conduits at the same time, facilitating the quick disconnection and reconnection of the mask assembly from the frame of the breathing system, as described above. In addition, the configuration of the shared connector channel for defogging gas, i.e., the channel between the inner and outer fittings, permits “swivel” operation of the connector, so that changing the relative angular orientation of the inner and outer fittings does not affect the flow of either the pressurized gas or the breathing gas.

[0057] Figs. 11A-11B are illustrations of a spray nozzle (50), Fig. 11A being a 3- dimensional view and Fig. 11B being a cross-sectional side view. Shown for each nozzle view is a nozzle outlet (100) from which gas is sprayed, nozzle mounts (102) for mounting the nozzle to an edge of the visor, and a nozzle inlet (104), which receives the pressurized gas. The mounts allow the angles of the nozzles to be adjusted, to maximize the defogging effect. In mask configuration that provide no anchoring points for the nozzles, mounts can be replaced with adhesive, glue, or by welding to the inner mask surface, or any other suitable means of connection.

[0058] Figs. 12A-12D illustrate the manifold (48) in perspective and cut-away views. The manifold may be configured to be positioned inside the mask opposite the mask mouthpiece, to receive pressurized defogging gas from the defogging tube and distribute the gas to separate conduits, i.e., the manifold extension tubes (96) described above, which in turn connect to the nozzles (50) that spray the gas. Shown in the figures are a pressurized gas inlet (110) of the manifold, which connects to the defogging tube, and outlet ports (112), which connect to the manifold extension tubes.

[0059] In specific embodiments, the location and positioning of the defogging tube (44) can be adjusted according to need, and it can pass either externally to existing tubes and hoses as an independent tube, or internally to reduce the risk of damage and entanglement. Accordingly, in certain embodiments of the mask assembly according to any of the embodiments above, the defogging tube (44) passes within said breathing hose (34) and is connected to a gas passage tube connector (94) within a breathing hose connector (38). Certain situations may require the disconnection of the mask from the breathing system, for example to replace the breathing system when the amount of gas in the compressed gas cylinder is low or if there is a malfunction. Moreover, the disconnection may be required while the user continues to wear the mask assembly (20). The breathing hose connector (38) may be a fast-release connector designed to enable easy and fast assembly and disassembly of the breathing hose from the breathing system.

[0060] The position and angle of the gas spray nozzles (50) within the mask are important, because, if not positioned well, defogging may be impaired or may cause discomfort to the user (e.g., gas sprayed over the eyes). Consequently, adjustment of the position and angle of the gas spray nozzles (50) can be important. Accordingly, in certain embodiments of the mask assembly according to any of the embodiments above, the gas spray nozzles (50) have mounts that fit against the visor edges in the mask permitting angular adjustment of the nozzle outlet, for example to enable targeting specific areas of the visor for focused defogging and / or improving user’s comfort.

[0061] As used herein, "possible locations of the spray nozzles in the mask" means the specific positions or areas within or on a mask where the nozzles that emit or spray a substance such as a mist or gas can be installed. The configuration and placement of these nozzles are designed to optimize the distribution of the emitted substance for specific applications, such as humidification or air purification. The exact placement can varydepending on the design of the mask, the intended use of the mask, and ergonomic considerations to ensure user comfort and effectiveness of the spray system. Nonlimiting examples of possible locations of the spray nozzles in the mask include:• Near the nose bridge area to directly target the nasal passages.• Embedded along the inner edge of the mask that contacts the cheek to provide broad coverage across the face.• At the lower portion of the mask near the chin to allow upward spray distribution.• Positioned on the outer surface of the mask to facilitate external spraying for cooling or disinfecting purposes.• Integrated into mask straps for even distribution around the perimeter of the face.

[0062] These examples are illustrative and do not restrict the placement of the spray nozzles to these locations only.

[0063] In certain embodiments, the mask assembly may include a gas-flow regulator associated with the defogging tube and designed to control or adjust the flow rate or speed of the gas over the visor.

[0064] In a further embodiment, the present invention provides a method of defogging a visor (24) of a mask (or hood) (22) of a breathing system, by supplying pressurized gas at a variable and / or controlled flow rate via a defogging tube (44) associated with a breathing hose (34) of the mask, and spraying said gas onto the inner surface of the visor using one or more gas spray nozzles (50) oriented within the mask (22). In specific embodiments of the above method, the breathing system is a closed-circuit rebreather (CCR), and said system further includes an exhalation hose (36) designed to connect the mask to a carbon dioxide (CO2) absorber for removal of CO2. In certain embodiments of the method, according to anyof the embodiments above, the defogging tube (44) passes within the breathing hose (34) and is connected to a passage (92) for the pressurized gas.

[0065] In an alternative embodiment, the present invention provides a method for defogging a visor (24) of a full-face mask (or hood) (22) used in a breathing system, including: (a) providing a mask assembly according to any of the embodiments above; (b) connecting the mask assembly to the breathing system; and (c) opening a compressed gas cylinder within the breathing system, thereby creating a flow of gas from said gas cylinder over said visor and defogging thereof.

[0066] To achieve effective defogging, it may be required to constantly spray gas over the visor. Accordingly, in certain embodiments of the method according to any of the embodiments above, the flow of gas through the defogging tube (44) and nozzles (50) is constant and is independent of the user’ s breathing rate and volume. Moreover, the gas speed and flow rate of the sprayed gas may remain constant throughout the entire usage of the system. Alternatively, adjustments of the flow rate, speed and / or direction of the gas may be required, e.g., due to hard conditions that cause higher perspiration and as a result increased fogging. Accordingly, in certain embodiments of the method according to any of the embodiments above, the mask further includes a valve associated with said defogging tube (44), and said method further includes a step of controlling or adjusting the flow rate and speed of the gas over the visor.

[0067] In a further aspect of the present invention, a system is provided for defogging a visor in a breathing system, the system including: a mask configured to be worn by a user; a compressed gas cylinder; one or more nozzles within the mask configured to direct gas onto the inner surface of the visor to maintain clear vision by reducing condensate formation; and a conduit from a gas regulator of the compressed gas cylinder to the one or more nozzles.

[0068] In certain embodiments, the system further includes one or more sensors (88) positioned within the mask to detect the presence and amount of fogging in the mask or on the visor. In specific embodiments thereof, the one or more sensors are configured to trigger an increase in gas flow when fogging is detected or when detected humidity exceeds a predefined threshold.

[0069] EXAMPLES

[0070] An example 1 provided by the present invention is a mask assembly (20) of a breathing system (50), the mask assembly having: (a) a full-face mask (22) with a visor (24); and (b) a breathing hose (34) extending from the full face mask at one end to a breathing hose connector (38) at the other end, to provide a breathing gas to the full face mask. The mask assembly also includes c) a defogging tube (44) extending within the breathing hose from the breathing hose connector (38) to the full-face mask (22), to provide a flow of a pressurized gas to one or more nozzles (50) inside the full-face mask. The one or more nozzles are oriented to spray the pressurized gas towards the inner surface of the visor (24). The mask assembly also includes d) the breathing hose connector (38), including an outer fitting (38B) and an inner fitting (38 A). The inner fitting is attached both to the breathing hose and to the defogging tube and connects into the outer fitting. The outer fitting connects to a breathing gas outlet of the breathing system to receive the breathing gas and further includes a pressurized gas port (46) to receive the pressurized gas from a pressurized gas source of the breathing system, which is separate from the breathing gas outlet. The inner and outer fittings are configured such that an outer surface groove (90A) of the inner fitting and an inner surface groove of the outer fitting, when joined, form a channel to direct the flow of the pressurized gas from the pressurized gas port through the channel to a pressurized gas passage (92) in the inner fitting that connects to the defogging tube.

[0071] An example 2 of the mask assembly includes the features of example 1 and the breathing hose connector has a quick-release fastener (40) for separating the inner fitting (38 A) from the outer fitting (38B), allowing quick-release of the breathing hose, including the defogging tube, from the breathing gas port and the pressurized gas source.

[0072] An example 3 includes features of either one of the above examples, and the pressurized gas source is a gas regulator (80) regulating pressure of gas from a compressed gas cylinder (70).

[0073] An example 4 includes features of any one of the above examples, and the defogging tube (44) enters the full-face mask (22) through a mouthpiece (32).

[0074] An example 5 includes features of any one of the above examples, and the breathing gas received by the breathing hose includes a portion of air previously exhaled by a user of the breathing system. The pressurized gas is dry gas having no previously exhaled air.

[0075] An example 6 includes features of any one of the above examples, and the pressurized gas is oxygen.

[0076] An example 7 includes features of any one of the above examples, and the one or more nozzles are mounted by adjustable mounting for adjusting the spray orientation to focus the pressurized gas on the visor.

[0077] An example 8 includes features of any one of the above examples, and the breathing system is a closed-circuit rebreather (CCR). The mask assembly further includes an exhalation hose (36) designed to connect the full-face mask to a carbon dioxide (CO2) absorber (72) of the breathing system that removes CO2 before the breathing gas is provided to the breathing hose.

[0078] An example 9 includes features of any one of the above examples, and the defogging tube (44) connects inside the full-face mask to a manifold (48) configured to distribute the pressurized gas to extension tubes (96) connected to one or more of the nozzles.

[0079] An example 10 includes features of any one of the above examples, and the inner and outer fittings can swivel with respect to each other when connected.

[0080] An example 11 includes features of any of the above examples, and further includes a valve (86) positioned along any part of a path from the pressurized gas source to the one or more nozzles to automatically or manually regulate the flow of the pressurized gas through the defogging tube.

[0081] An example 12 includes the features of example 11, and the valve is set to provide a constant-flow of pressurized gas independent of a user’s breathing rate and breathing volume.

[0082] An example 13 includes the features of example 11, and further includes one or more sensors positioned within the full-face mask to detect fogging of the visor. The sensors are operatively connected to the valve to vary the flow when fogging is detected or when humidity exceeds a predefined threshold.

[0083] In certain embodiments, the systems and methods according to any of the embodiments above include an inner screen instead of or in addition to a clear visor, and the defogging nozzles are designed to defog said screen. In such configurations, such systems may include a sensor or camera configured to transfer an image or video from the exterior of the mask onto the inner screen.

[0084] TABLE OF REFERENCES

[0085] It should be understood that all the limitations and definitions mentioned above in relation to one or more of the above systems and methods, apply mutatis mutandis to all the systems and methods mentioned and claimed, even if not explicitly referred thereto.

Claims

CLAIMS1. A mask assembly (20) of a breathing system (50), the mask assembly comprising:(a) a full-face mask (22) with a visor (24);(b) a breathing hose (34) extending from the full face mask at one end to a breathing hose connector (38) at the other end, to provide a breathing gas to the full face mask; c) a defogging tube (44) extending within the breathing hose from the breathing hose connector (38) to the full-face mask (22), to provide a flow of a pressurized gas to one or more nozzles (50) inside the full-face mask, wherein the one or more nozzles are oriented to spray the pressurized gas towards the inner surface of the visor (24); and d) the breathing hose connector (38), comprising an outer fitting (38B) and an inner fitting (38 A), wherein the inner fitting is attached both to the breathing hose and to the defogging tube and connects into the outer fitting, wherein the outer fitting connects to a breathing gas outlet of the breathing system to receive the breathing gas and further comprises a pressurized gas port (46) to receive the pressurized gas from a pressurized gas source of the breathing system that is separate from the breathing gas outlet, and wherein an outer surface groove (90A) of the inner fitting and an inner surface groove (90B) of the outer fitting, when joined, form a channel to direct the flow of the pressurized gas from the pressurized gas port to a pressurized gas passage (92) in the inner fitting that connects to the defogging tube.

2. The mask assembly of claim 1, wherein the breathing hose connector has a quick-release fastener (40) for separating the inner fitting (38 A) from the outer fitting (38B), allowing quick-release of the breathing hose, including the defogging tube, from the breathing gas port and the pressurized gas source.

3. The mask assembly of any one of the preceding claims, wherein the pressurized gas source is a gas regulator (80) regulating pressure of gas from a compressed gas cylinder (70).

4. The mask assembly of any one of the preceding claims, wherein the defogging tube (44) enters the full-face mask (22) through a mouthpiece (32).

5. The mask assembly of any one of the preceding claims, wherein the breathing gas received by the breathing hose includes a portion of air previously exhaled by a user of the breathing system, and wherein the pressurized gas is dry gas having no previously exhaled air.

6. The mask assembly of any one of the preceding claims, wherein the pressurized gas is oxygen.

7. The mask assembly of any one of the preceding claims, wherein the one or more nozzles are mounted by adjustable mounting for adjusting the spray orientation to focus the pressurized gas on the visor.

8. The mask assembly of any one of the preceding claims, wherein the breathing system is a closed-circuit rebreather (CCR), and wherein the mask assembly further comprises an exhalation hose (36) designed to connect the full-face mask to a carbon dioxide (CO2) absorber (72) of the breathing system that removes CO2 before the breathing gas is provided to the breathing hose.

9. The mask assembly of any one of the preceding claims, wherein the defogging tube (44) connects inside the full-face mask to a manifold (48) configured to distribute the pressurized gas to extension tubes (96) connected to one or more of the nozzles.

10. The mask assembly of any one of the preceding claims, wherein the inner and outer fittings can swivel with respect to each other when connected11. The mask assembly of any of the preceding claims, further including a valve (86) positioned along any part of a path from the pressurized gas source to the one or more nozzles to automatically or manually regulate the flow of the pressurized gas through the defogging tube.

12. The mask assembly of claim 11, wherein the valve is set to provide a constant-flow of pressurized gas independent of a user’s breathing rate and breathing volume.

13. The mask assembly of claim 11, further comprising one or more sensors positioned within the full-face mask to detect fogging of the visor and operatively connected to the valve to vary the flow when fogging is detected or when humidity exceeds a predefined threshold.

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