Closed-circuit rebreather positive pressure management

Abstract

Systems and methods are provided for managing face mask pressure of a breathing system. The system includes an inhalation blower that pumps breathing air from a CO2 absorber to the face mask, an exhalation blower that pumps breathing air from the face mask to the CO2 absorber, and a controller. The controller is configured for receiving sensor signals from one or more pressure sensors and / or flow meters indicative of user respiration and of face mask pressure, for responsively issuing controller signals to provide blower pressure countering a face mask pressure drop during inhalation, and to counter a face mask pressure increase during exhalation, while maintaining a net positive face mask pressure with respect to ambient air pressure.

Description

CLOSED-CIRCUIT REBREATHER POSITIVE PRESSURE MANAGEMENT FIELD OF THE INVENTION

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

[0002] Self-contained breathing systems for land use 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 systems in which exhaled air is 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] Common issues encountered with such breathing systems are (1) the difficulty of maintaining positive pressure in the face mask at all times, especially during high physical exertion, (2) breathing through the scrubber, and (3) the limited time for operation. Disadvantages of the prior art are overcome by the present system and methods.SUMMARY

[0006] The present invention provides devices and methods for enhancing a closed-circuit rebreather (CCR) system designed to operate in conditions with insufficient oxygen or with hazardous levels of toxic gases. A CCR typically includes: (a) a compressed breathing gas cylinder; (b) a gas regulator attached to the cylinder and designed to provide breathing gas at a regulated pressure; (c) a face mask configured to be worn by a user, the face mask covering a user’s mouth and nose, and generally including a visor, as well, for protection of the user’s eyes; (d) a carbon dioxide (CO2) absorber with CO2 scrubber material; and (e) a counterlung connected to the CO2 absorber to receive exhaled air exiting the CO2 absorber. Devices, systems, and methods provided by the present invention include blowers (i.e., air pumps) designed to ease breathing by a user, while maintaining a positive face mask pressure for secure operation.BRIEF DESCRIPTION OF DRAWINGS

[0007] 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:

[0008] Fig. l is a schematic, block diagram of a breathing system including blowers for managing face mask pressure, according to some embodiments of the present invention;

[0009] Fig.2 is a schematic, block diagram of the breathing system, together with valves for hybrid operation, according to some embodiments of the present invention;

[0010] Fig. 3 is a schematic, mechanical drawing of the breathing system indicating physical geometries of system elements, according to some embodiments of the present invention;

[0011] Fig. 4 is a schematic, mechanical drawing of an inhalation manifold assembly providing breathing air to the inhalation tube of the breathing system, according to some embodiments of the present invention;

[0012] Fig. 5 is a schematic, exploded, mechanical drawing of the inhalation manifold assembly providing breathing air to the inhalation tube of the breathing system, including a manifold to which other elements of the subassembly are connected, according to some embodiments of the present invention;

[0013] Fig. 6 is a schematic, mechanical drawing of the manifold of the inhalation manifold assembly, according to some embodiments of the present invention;

[0014] Fig. 7 is a schematic, cut-away drawing of a bypass route for air flow in the manifold, according to some embodiments of the present invention;

[0015] Figs. 8A-8B are schematic drawings of a CO2 absorber of the breathing system, including a canister and canister cover, according to some embodiments of the present invention;

[0016] Fig. 9 is a schematic, cut-away drawing of a manifold of the canister cover, providing a bypass route for air flow in the exhalation valve, according to some embodiments of the present invention;

[0017] Figs. 10A-10B are schematic drawings of a shutter of the exhalation blower, according to some embodiments of the present invention;

[0018] Figs. 11A-11B are additional schematic drawings of a flow meter of a mouthpiece of the face mask, according to some embodiments of the present invention;

[0019] Fig. 12 is a table of the blower and shutter operation during a breathing cycle, showing the operating changes during inhalation and exhalation, according to some embodiments of the present invention; and

[0020] Figs. 13A-13D are graphs of the blower and shutter operation during a breathing cycle, showing the operating changes during inhalation and exhalation, according to some embodiments of the present invention.DETAILED DESCRIPTION

[0021] Embodiments of the present invention provide devices, systems, and methods to ease breathing by a user of a closed-circuit rebreather (CCR), while maintaining a positive face mask pressure for secure operation.

[0022] The invention is described by reference to the accompanying drawings, which are to be considered only as representative examples 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 not combined 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.

[0023] Fig. 1 shows a breathing system 100 that includes a face mask 104 and elements of a CCR system. The face mask receives breathing air, or “breathing gas,” from an inhalation tube or hose 112 and releases exhaled air to an exhalation tube 114. Herein, the term breathing air refers to air that is breathable, typically air at a pressure above or equal to atmospheric pressure, with a minimum oxygen content of 19.5 percent oxygen.

[0024] During CCR operation, the breathing air is recycled in the breathing system. Exhaled air is released from the face mask to the exhalation tube that leads to a CO2 absorber 120 (i.e., “scrubber”). Air passes through the CO2 absorber to reach a counterlung 122 (i.e., gas reservoir), which provides the recycled breathing air to the face mask.

[0025] The recycled air from the counterlung is supplemented by breathing air supplied by one or more compressed gas cylinders 130. In typical configurations for land use, the compressed gas cylinder contains medical grade oxygen, but other gas configurations may be used that mix oxygen with other gases (e.g., nitrogen, argon, and / or helium). A gas configuration may be “dry air,” having no moisture. The compressed gas is typically at a pressure level 131, which may be, for example, two hundred atmospheres (atm) or more.

[0026] In examples of the present invention, the compressed gas may be decompressed in two stages. A first stage regulator 132 may reduce the pressure to a “service line” pressure 133, i.e., a pressure that is typical for many industrial applications, such as 5-10 atm. A second stage regulator 134 may then reduce the service level pressure to a breathing air line pressure 135 of approximately 1 atm, which may be supplied at a constant rate, for example, in a range of 0.5 to 2.5 liters / minute. 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.

[0027] As indicated in the figure, the inhalation tube conveys breathing air from the compressed gas cylinder to the face mask, when a user is inhaling, and may also convey breathing air to the counterlung (in particular when the user is not inhaling, that is, when the user is exhaling). The system may be configured such that, if the counterlung pressure drops, additional “demand” gas may be provided by the second stage regulator to the counterlung.

[0028] Monitoring of the system operation may include receipt of signals from multiple pressure and gas sensors, such as gas pressure sensors 140 (Pl) and 142 (P2), positioned before and after the face mask, respectively. A CO2 sensor 144 (P3) may also be positioned after the counterlung to confirm CO2 absorber operation. Additional sensors may include a service line pressure sensor 146 (P4), and an APR pressure sensor 152 (P5).

[0029] Two blowers, an inhalation blower 212 (Bl) and an exhalation blower 214 (B2) are provided to control the pressure of the breathing air in the face mask, typically configured to maintain in the face mask a positive pressure (for example not dropping below +0.5 mbar) above atmospheric pressure, while not exceeding a maximum pressure threshold like for example +10 mbar above atmospheric pressure. The inhalation blower 212 is configured to pump breathing air into the face mask, increasing the pressure both to ease inhalation and to ensure a positive pressure relative to ambient air pressure. The exhalation blower 214 is configured to pump breathing air from the face mask, easing the user exertion required to breathe into the scrubber. A controller 220 (also referred to herein as a “blower controller”), typically having a processor and memory, typically manages the operation of both blowers according to stored instructions, controlling their on / off states and adjusting their speeds in response to air pressure measurements taken from the pressure sensors Pl and / or P2. The controller may also receive signals from additional sensors in the system, including the gas pressure sensors 140 (Pl) and 142 (P2). Based on the pressure signals, the controller adjusts the speeds of the blowers, easing a user's inhalation and exhalation while maintaining apositive pressure in the face mask. That is, the controller typically adjusts the blower speeds to maintain air pressure at sensor Pl and / or sensor P2 that are greater than ambient pressure by a preset positive pressure increment.

[0030] In addition, the system may include one or both of an inhalation shutter 222 and an exhalation shutter 224. The exhalation shutter may be positioned along (i.e., in or in line with) the exhalation tube between the exhalation valve and the exhalation blower, and the inhalation shutter may be positioned along the inhalation tube between the inhalation valve and the inhalation blower. When the exhalation shutter is provided, either alone or together with the inhalation shutter, the controller may narrow or close the exhalation shutter when a user is inhaling, reducing or stopping the flow of breathing air to the exhalation blower and thereby allowing air pressure in the face mask to rise during inhalation to reduce inhalation exertion. The controller can subsequently open the exhalation shutter when the user exhales. Opening the exhalation shutter causes the face mask pressure to be reduced quickly, as the exhalation blower does not have to power up to a desired speed, but can remain in operation. Similarly, when the inhalation shutter 222 is provided (either alone or with the exhalation shutter), the controller may narrow or close the inhalation shutter, reducing or stopping the breathing air flow from the inhalation blower to the mask when a user is exhaling, thereby preventing the air pressure in the face mask from building up and thereby reducing exertion during exhalation. The controller can subsequently open the inhalation shutter 224 when the user inhales, so that the face mask pressure can be increased quickly due to the pressure of the inhalation blower, in order to assist with inhalation. That is, the inhalation blower may be operating before the shutter is opened and therefore the change in pressure occurs more rapidly than is possible when the blower is not already operating. Operation of one or both shutters therefore permits a faster change in pressure than could be achieved by merely changing the blower speeds. To determine when a user is inhaling or exhaling, the controllermay either rely on pressure sensors Pl and P2, or may receive a signal indicative of breathing air flow from a flow meter 226, typically positioned in the mouthpiece of the face mask and described further hereinbelow. The rate of air flow measured (for example in liters per second) by the flow meter is indicative of respiration, as inhalation causes a flow that is the opposite of the flow of exhalation. One or more additional (or alternative) flow meters may also be positioned in the inhalation and / or exhalation tubes to similarly provide indications of inhalation and exhalation.

[0031] Note that the blowers and controller typically require a power source, such as a battery, not shown. Signals communicated to and from the controller may be wired or wireless.

[0032] In some embodiments, the inhalation blower 212, the counterlung 122, and the 2ndstage regulator 134 connect to a common manifold, creating an inhalation manifold assembly 170 (also referred to herein as a 2ndstage assembly), described further hereinbelow.

[0033] The blowers, shutters and controller, working together, provide several advantages, including:1. Precise control over breathing air pressure2. Significant reduction in breathing resistance for the user3. Precise pressure control in face mask to maintain positive pressure, enhancing safety and comfort4. Improved overall comfort for extended use5. Rapid response to changes in breathing patterns6. Efficient use of the compressed gas supply

[0034] Fig.2 is a schematic block diagram of an enhanced breathing system 200, which includes all the components described in Fig. 1, with the addition of two pressure-actuated valves: an air-purifying respirator (APR) valve 154 and an exhalation valve 156. The additionof these valves allows for a hybrid mode of operation, switching between the CCR mode described above with respect to Fig. 1 and an APR mode receiving external breathing air from an air-purifying respirator. The APR valve 154 is connected to receive breathing air from an APR unit 106 and to provide breathing air to the face mask. The exhalation valve 156 is positioned in the path of the exhalation tube 114, to switch the flow of breathing air between an exhaust outlet 160 and the CO2 absorber. The hybrid capability allows for more flexible use of the system in varying environmental conditions. Both valves are typically designed to be actuated according to air pressure indicative of whether or not the compressed gas cylinder is open. In some embodiments, the valves are air-pressure actuated, with pneumatic actuators.

[0035] For example, the APR valve 154 and the exhalation valve 156 may be connected directly to the service line 133, such that the service line pressure triggers their opening and closing. This pressure-based actuation ensures a reliable and quick transition between closed-circuit and APR modes. When the compressed gas cylinder is open, creating pressure in the service line, the APR valve 154 closes, preventing air flow from the APR unit, and the exhalation valve 156 directs exhaled air to the CO2 absorber for closed-circuit operation.

[0036] When the compressed gas cylinder is closed, resulting in no pressure in the service line, the APR valve 154 opens, allowing air flow from the APR unit, and the exhalation valve 156 directs exhaled air to the exhaust outlet 160 for open-circuit operation. This pressure-based valve operation provides a fail-safe mechanism, ensuring that the system defaults to APR mode if the compressed gas supply is depleted or shut off.

[0037] The controller 220 may also be configured to monitor the operation of these valves, coordinating their function with the blowers and shutter to maintain optimal breathing conditions in both closed-circuit and open-circuit modes. The controller may use the service line pressure sensor 146 (P4) to monitor the state of the valves and adjust the systemoperation accordingly. For example, the controller may close the shutter and / or turn off the exhalation blower when the system is set to APR mode, for example by sensing the service pressure (P4) to determine that the compressed gas cylinder is closed (and / or by sensing the exhalation pressure sensor P2 to determine that the exhalation valve is open, expelling air to the environment). The controller may also be configured to shut off the inhalation blower in APR mode, in which case breathing air may flow through a blower bypass (described below with respect to Fig. 7).

[0038] In some embodiments, the APR valve is also connected to the inhalation manifold 170, which, as described above, may connect the inhalation blower, the 2ndstage regulator, and the counterlung outlet.

[0039] An additional APR sensor 152 (P5) may be included to detect whether the APR unit is connected to the system, providing further data for system management, such as operation of the inhalation blower to compensate for the APR pressure level.

[0040] This enhanced system retains all the advantages of the system in Fig. 1, while adding the flexibility of hybrid operation. The addition of the pressure-actuated valves and exhaust outlet allows for adaptation to different environmental conditions, potentially extending the overall operational time of the system and providing an additional layer of safety through its fail-safe design.

[0041] Fig.3 is a schematic, mechanical drawing of the breathing system 200 indicating physical geometries of various system elements, including those described above (with respect to Figs. 1 and 2). The face mask 104 is shown connected to the inhalation tube 112 and to the exhalation tube 114 by way of a mouthpiece 302. The exhalation tube is shown connecting to the exhalation valve 156 by way of a connector 304. The CO2 absorber has an absorber cover 308, which is a manifold to which the exhalation blower 214 and the exhalation blower shutter 222 may also be connected.

[0042] The exhalation valve is shown connecting to the CO2 absorber 120 by an absorber cover connector 306. In this configuration, the connector 306 connects to the exhalation blower shutter 222. The CO2 absorber 120 also includes a CO2 absorber canister 310, which receives exhaled air from the absorber cover 308 and contains CO2 scrubber material for removing CO2 for the closed circuit.

[0043] The counterlung 122 is not shown in the figure, as it is typically positioned to cover the CO2 absorber. Shown are connectors to the counterlung, these being a connector 312 from the CO2 absorber, and a connector 314 to the inhalation manifold assembly 170.As described above, the inhalation manifold assembly may include the inhalation blower 212, the APR valve 154, and the 2ndstage regulator 134. The APR valve 154 connects to the APR 106. The 2ndstage regulator 134 connects to the 1ststage regulator 132, which in turn connects to the compressed gas cylinder 130. Also shown is a gas cylinder valve 320, for opening and closing the gas cylinder.

[0044] Also shown is an inhalation tube connector 330, connecting the inhalation tube to the inhalation manifold assembly. An APR tube 340 may connect the APR to the APR valve. The elements of the CCR subsystem, including the CO2 absorber 120 and the compressed gas cylinder 130 are typically mounted to a frame 350 that a user carries as a backpack. In further variations, the APR may also be mounted. It should be noted that the inhalation tube connector 330, like the connectors 304 and 306 along the exhalation tube, may be a quick-connect type of connector, permitting quick the separation of the face mask and tubes from the frame 350.

[0045] Fig. 4 is a schematic, mechanical drawing of the inhalation manifold assembly 170, which, as described above, may be a subassembly of either of systems 100 or 200. The assembly includes an inhalation tube manifold, also referred to as a 2ndstage manifold 400, to which other elements are connected. As indicated, those elements may include theinhalation blower 212, the APR valve 154, and the 2ndstage regulator 134, shown together with the connector 314 to the counterlung. Through the connector 314, the counterlung may provide breathing air to the space within the inhalation tube manifold 400 and may also receive breathing air from that space (for example, when a user is exhaling). Also shown in the figure is the inhalation tube connector 330, connected to a manifold connector 410. Also shown is a connector 420 of the APR valve, connecting the APR valve to the APR tube 340 described above. A 2ndstage regulator connector 430 provides an inlet for the decompressed breathing air from the compressed gas cylinder.

[0046] Fig. 5 is a schematic, exploded, mechanical drawing of the inhalation manifold assembly 170, including the inhalation tube manifold 400 to which the other elements connect. As indicated, those elements may include the inhalation blower 212 and the APR valve 154, as well as the 2ndstage regulator 134, not shown. Also shown in the figure are a pneumatic actuator 500 of the APR valve, described above, and clips 510, which may be included to connect the APR valve to the inhalation tube manifold. As indicated, the manifold may have a manifold socket 520 for the inhalation blower, as well as a connector 530 for the inhalation tube. The assembly is modular in the sense that the functions of blowers and vents may be added if a given field operation requires either or both, and may be removed if a given operation does not require either or both. Caps may be connected in place of the APR valve and / or blower according to requirements. The inhalation tube connector 330, connecting to the inhalation tube manifold 400 by way of the inhalation manifold assembly connector 410.

[0047] Fig. 6 is a schematic, mechanical drawing of the inhalation manifold 400, indicating with black arrows the flow of breathing air into and out of the manifold. Breathing air flows from the manifold 400 to the inhalation tube through the 2ndstage outlet 530. The breathing air may be pumped through the manifold, to assist with breathing, when theinhalation blower described above is fit into the inhalation blower socket 520. During operation in APR mode, breathing air may flow into the manifold from the APR valve connector 420. During operation in CCR mode, breathing air may flow into the manifold from the 2ndstage regulator connector 430 (also referred to herein as the decompressed air inlet). In either case, breathing air may flow from the manifold both to and from the counterlung, through the counterlung connector 314.

[0048] Fig. 7 is a schematic, cut-away drawing of a bypass route for air flow in the inhalation tube manifold 400. The inhalation blower (not shown in the cut-out schematic), when operating, pulls breathing air through the path indicated by the hashed lines, with breathing air that enters from the counterlung being conveyed to the inhalation tube outlet 530. However, when the inhalation blower fails or is stopped (for example by the blower controller), breathing air passes through a diaphragm referred to as an inhalation manifold blower bypass 700, as indicated in the figure.

[0049] Figs. 8A-8B are schematic, mechanical drawings of the CO2 absorber 120, from two perspectives, both views showing the CO2 absorber cover 308 and the CO2 absorber canister 310 which typically holds scrubber material, such as a mixture of calcium hydroxide and sodium hydroxide. Also shown are the exhalation blower 214, the shutter 222, and the exhalation tube connector 310 to the CO2 absorber (connecting to the shutter in the configuration shown). Like the inhalation manifold assembly, the CO2 absorber cover is modular, such that the blower and shutter features can be removed when not required. Also shown is a connector 802 to a CO2 absorber fan, which may be attached for cooling the canister.

[0050] Fig.9 is a schematic, cut-away drawing of the manifold of the canister cover 308, providing bypass routes 900 for air flow in the exhalation valve if the blower fails.

[0051] Figs. 10A-10B are schematic drawings of shutters 222 and 224 of the respective inhalation and exhalation blowers, in respective closed and open positions. Shutters also have a signal connection (e.g., an electrical connection) to the controller (not shown).

[0052] Figs. 11A-11B are schematic drawings of exploded views of a flow meter 1100 of the mouthpiece 302 of the face mask 104, showing how the flow meter fits into the mouthpiece before the mouthpiece is attached to the face mask. Various technologies known in the art may be used for the flow meter, such as mechanical meters, Venturi meters, and thermal flow meters. Mechanical meters use a physical element within the flow stream to measure flow rate, such as a turbine, propeller, or piston. Venturi meters utilize the Bernoulli principle to determine flow rate. As fluid flows through a tube and into a constricted area, its velocity increases and pressure decreases. The pressure difference between a wider section and the constricted area indicates the flow rate. In typical thermal flow meters, two temperature sensors are used, one measuring the fluid's temperature, the other being heated to maintain a constant temperature difference between the sensors. The heat required is proportional to the mass flow rate of the fluid or gas.

[0053] Fig. 12 and Figs. 13A-13D are respectively a table and graphs of the blower and shutter operation during a breathing cycle, showing the operating changes during inhalation and exhalation. The table of Fig. 12 shows that during exhalation, the inhalation blower Bl is off or operating at a low speed, and the exhalation blower B2 is at a higher speed, helping to draw out exhaled air. The exhalation shutter is open and the inhalation shutter is closed. By contrast, during inhalation, the inhalation blower Bl is high (i.e., the speed is high), and the exhalation blower is off or low. The exhalation shutter is closed and the inhalation shutter is open. (As described above, the invention may also be provided with only a single blower and or shutter.)

[0054] Figs. 13A-13D are more detailed graphs indicating the blower and shutter operation during breathing cycles. “Events” TO to T4 are indicated, these being indications of sensor readings (i.e., signals) that trigger actions by the controller, such as shutter and blower control.

[0055] As shown in Fig. 13A, air flow rate is positive during inhalation (the period from TO to T2) and negative during exhalation (the period from T2 to T4), the flow rate being measured by flow meter Fl, described above (typically positioned in the face mask mouthpiece). While the flow rate during inhalation increases from zero (at TO) to a maximum (at Tl), the inhalation shutter is open to its maximum level (e.g., 100%), as shown in Fig.13B. During this period, the speed of the inhalation blower may also be increased by the controller from a “stand-by” speed, for example 50% of maximum rpm, to a full rate, such as 100% (Fig. 13C) to ensure that the air pressure in the mask (as measured by the air pressure sensors inside the breathing tubes) does not drop below a minimum threshold (e.g., 0.5 mbar above ambient pressure) thereby ensuring a “positive pressure” in the face mask (Fig. 13D).This adjustment ensures a reduction or increase in air pressure as needed to prevent the pressure from exceeding safe thresholds, especially during periods of increased physical exertion. That is, the controller may be configured to increase the blower speed(s) as the breathing cycle rate increases (as measured, for example, by cycles indicated by the flow meter).

[0056] Towards the end of the inhalation period, the controller closes the inhalation shutter and opens the exhalation shutter (Fig. 13B), to allow the exhalation blower to begin dissipating the pressure increase. The controller also may increase the inhalation blower (Bl) speed to ensure that a maximum pressure (e.g., 10-12 mbar above ambient pressure) is not exceeded. In summary, the air flow rates of the blowers, which is determined by blower fan rotations per minute (rpm) and by the shutter opening, are changed in real time by thecontroller, depending on the air pressure measured at the pressure sensors and the flow rate measured by the face mask flow meter. The controller is configured to keep a positive pressure (with respect to atmospheric pressure) in the breathing tubes and face mask, within certain minimum and maximum pressure limits. The minimum limit is typically at least 0.5 mbar above ambient air pressure, while the maximum is typically below 10-12 mbar above ambient air pressure.

[0057] Note that, as indicated in Fig. 13D, if the blowers and shutters are switched off or disabled (for example, due to loss of battery power), the result is a much lower pressure during inhalation increasing user exertion, as well as a significantly higher pressure during exhalation, with the resistance to exhalation being analogous to inflating a balloon.

[0058] It is to be understood that mask pressure control can be achieved with one blower, rather than two, and without shutters. Optionally, a second blower can be added to improve operation or a shutter can be added to the first blower. A further enhancement is to employ both additional elements, that is, a second blower and a shutter, and a further enhancement is to add a second shutter.

[0059] EXAMPLES

[0060] A first example of the present invention is apparatus for a breathing system (represented by systems 100 or 200 described above) that typically includes a face mask, an APR unit, and a CCR subsystem, where the CCR subsystem includes a compressed gas cylinder and a carbon dioxide (CO2) absorber. The apparatus includes:• an inhalation blower, configured to pump breathing air from the CO2 absorber, typically through a counterlung, to the face mask through an inhalation tube;• an exhalation blower, pumping breathing air from the face mask to the CO2 absorber through an exhalation tube;• a controller configured with memory that stores instructions, configured to receive sensor signals from one or more pressure sensors and / or flow meters indicative of user respiration and of face mask pressure, to issue responsively controller signals to provide blower pressure countering a face mask pressure drop during inhalation, and to counter a face mask pressure increase during exhalation. The pressure adjustments are made so as to maintain a net positive face mask pressure with respect to ambient air pressure both during inhalation and during exhalation.

[0061] In a further example, the controller signals to provide blower pressure countering a face mask pressure drop during inhalation may be issued to one or more of the inhalation blower, to increase the inhalation blower speed; and / or to an inhalation shutter, to open, thereby permitting breathing air flow from the inhalation blower to the face mask; and / or to the exhalation blower, to decrease the exhalation blower speed; and / or to an exhalation shutter, to restrict breathing air flow from the face mask to the exhalation blower. Alternatively, or additionally, the signals to provide blower pressure countering a face mask pressure increase during exhalation may be issued to one or more of the inhalation blower, to decrease the inhalation blower speed; and / or to an inhalation shutter, to restrict breathing air flow from the inhalation blower to the face mask; and / or to the exhalation blower, to increase the exhalation blower speed; and / or to an exhalation shutter, to open, thereby permitting breathing air flow from the face mask to the exhalation blower.

[0062] A further example of the present invention includes the above features as well as an inhalation manifold including four openings: 1) an inhalation tube outlet, from which breathing air is provided to an inhalation tube of the face mask; 2) a decompressed breathing air inlet, into which breathing air flows from the compressed gas cylinder, reduced in pressure by one or more regulators; 3) an inhalation blower socket in which to position the inhalationblower; and 4) a counterlung connector, connecting to a counterlung of the CCRthat receives breathing air from the CO2 absorber.

[0063] In a further example, the inhalation manifold also includes an air-purifying respirator (APR) valve inlet, connecting to an APR valve that opens and closes a passage for air flow from an APR unit.

[0064] In a further example, the inhalation manifold also includes a bypass route for the breathing air in the inhalation manifold to bypass the inhalation blower to reach the inhalation tube connector during failure of the inhalation blower.

[0065] A further example of the present invention may include the features of any one of the above examples and the CO2 absorber may include a canister and a canister cover, where the canister cover includes: 1) an exhalation tube inlet, connecting to an exhalation tube of the face mask; 2) an exhalation blower socket for the exhalation blower; and 3) a canister cover outlet to the CO2 absorber canister. The canister cover may also include a bypass route for the breathing air in the CO2 canister cover to bypass the exhalation blower to reach the CO2 absorber canister in the event of failure of the exhalation blower.

[0066] A further example of the present invention is apparatus including any one of the features of the above examples, and including, in the exhalation tube, a shutter. Reducing the exhalation blower pressure during inhalation includes triggering partial or complete closure of the shutter, and increasing the exhalation blower pressure during exhalation includes triggering opening of the shutter.

[0067] A further example of the present invention is apparatus including any one of the features of the above examples and including an exhalation valve. The exhalation valve expels breathing air to the environment when the compressed gas cylinder is closed and breathing air is supplied from an air-purifying respirator (APR). The controller may also be configured to stop the exhalation blower when breathing air is supplied from the APR.

[0068] A further example of the present invention is a rebreather system for land-based rebreather operation that may include: a face mask; a closed-circuit rebreather (CCR) subsystem including a compressed gas cylinder and a carbon dioxide (CO2) absorber; an inhalation blower, pumping breathing air from the CO2 absorber (typically through a counterlung) to the face mask; an exhalation blower, pumping breathing air from the face mask to the CO2 absorber (which conveys the air to the counterlung); one or more pressure sensors indicative of face mask pressure during inhalation and exhalation; a controller configured to receive pressure indications of inhalation and exhalation from the pressure sensors, to increase the inhalation tube pressure and to reduce the exhalation blower tube pressure during inhalation, and to decrease the inhalation tube pressure and to increase the exhalation tube pressure during exhalation, while maintaining a net positive face mask pressure with respect to ambient air pressure.

[0069] A further example of the present invention is a method for setting face mask breathing air pressure of a closed-circuit rebreather (CCR), such as the CCR of the above examples.

[0070] In another example, the apparatus may incorporate a user-interface module capable of displaying information related to the detected object and receiving user inputs to modify the operational parameters of the device, system, and / or breathing system.

[0071] In yet another example, the apparatus may include a memory component for storing data related to an object detected by a sensor, which may help in subsequent processing or historical analysis of object encounters.

[0072] In a further example, the apparatus according to any one of the examples above is equipped with a communication module configured to transmit received data to a remote server or another device or system within a network for additional processing or for generating alerts.

[0073] 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. Furthermore, it should be understood that a teaching that two elements are combined in a claimed combination may be understood as also allowing for a claim in which the two elements are not combined with each other, but may be used alone or combined with other combinations. The exclusion of any disclosed element of the invention from the claims is explicitly contemplated as being within the scope of the invention.

[0074] TABLE OF REFERENCES

Claims

CLAIMS1. Apparatus for a breathing system, wherein the breathing system includes a face mask and a closed-circuit rebreather (CCR) subsystem supplying breathing air to the face mask, wherein the CCR subsystem includes a compressed gas cylinder and a carbon dioxide (CO2) absorber, the apparatus comprising:an inhalation blower, configured to pump breathing air from the CO2 absorber to the face mask through an inhalation tube;an exhalation blower, configured to pump breathing air from the face mask to the CO2 absorber through an exhalation tube;a controller comprising memory having instructions that, when executed, perform steps of:receiving sensor signals from one or more pressure sensors and / or flow meters indicative of user respiration and of face mask pressure;responsively issuing controller signals to adjust blower pressure provided by one or both of the inhalation blower and the exhalation blower to counter a face mask pressure drop during inhalation, and to counter a face mask pressure increase during exhalation, while maintaining a net positive face mask pressure with respect to ambient air pressure.

2. The apparatus of claim 1, wherein the controller signals to adjust blower pressure, to counter a face mask pressure drop during inhalation, are issued by the controller to the inhalation blower to increase the inhalation blower speed, and / or to an inhalation shutter to open, permitting breathing air flow from the inhalation blower to the face mask, and / or to the exhalation blower to decrease the exhalation blower speed, and / or to an exhalation shutter to restrict breathing air flow from the face mask to the exhalation blower.

3. The apparatus of either one of the above claims, wherein the controller signals to adjust blower pressure, to counter a face mask pressure increase during exhalation, are issued by the controller to the inhalation blower to decrease the inhalation blower speed, and / or to an inhalation shutter to restrict breathing air flow from the inhalation blower to the face mask, and / or to the exhalation blower to increase the exhalation blower speed, and / or to an exhalation shutter to open, permitting breathing air flow from the face mask to the exhalation blower.

4. The apparatus of claim 1, further comprising an inhalation manifold comprising four openings: 1) an inhalation tube outlet, from which breathing air is provided to the inhalation tube; 2) a decompressed breathing air inlet, into which breathing air flows from the compressed gas cylinder, reduced in pressure by one or more regulators; 3) an inhalation blower socket in which to position the inhalation blower; and 4) a counterlung connector, connecting to a counterlung of the CCR that receives breathing air from the CO2 absorber.

5. The apparatus of claim 4, wherein the inhalation manifold further comprises an air-purifying respirator (APR) valve inlet, connecting to an APR valve that opens and closes a path from an APR unit.

6. The apparatus of claim 4, wherein the inhalation manifold further comprises a bypass route for the breathing air in the inhalation manifold to bypass the inhalation blower to reach the inhalation tube connector during failure of the inhalation blower.

7. The apparatus of any one of the above claims, wherein the CO2 absorber comprises a CO2 absorber canister and a canister cover, the canister cover comprising: 1) an exhalation tube inlet, connecting to the exhalation tube; 2) an exhalation blower socket for the exhalation blower; and 3) a canister cover outlet to the CO2 absorber canister.

8. The apparatus of claim 7, wherein the canister cover further comprises a bypass route for the breathing air in the CO2 canister cover to bypass the exhalation blower to reach the CO2 absorber canister during failure of the exhalation blower.

9. The apparatus of any one of the above claims, wherein increasing the inhalation tube pressure comprises increasing the inhalation blower speed and decreasing the inhalation tube pressure comprises decreasing the inhalation blower speed.

10. The apparatus of any one of the above claims, wherein increasing the exhalation tube pressure comprises increasing the exhalation blower speed and decreasing the exhalation tube pressure comprises decreasing the exhalation blower speed.

11. The apparatus of any one of the above claims, wherein the exhalation tube comprises an exhalation valve, wherein the exhalation valve expels breathing air to the environment when the compressed gas cylinder is closed and breathing air is supplied from an air-purifying respirator (APR) and wherein the controller is configured to stop the exhalation blower when breathing air is supplied from the APR.

12. A rebreather system for land-based rebreather operation, comprising:a face mask;a closed-circuit rebreather (CCR) subsystem comprising a compressed gas cylinder and a carbon dioxide (CO2) absorber;an inhalation blower, pumping breathing air from the CO2 absorber canister to the face mask;an exhalation blower, pumping breathing air from the face mask to the CO2 absorber; a controller comprising memory having instructions that, when executed, perform steps of:receiving sensor signals from one or more pressure sensors and / or flow meters indicative of user respiration and of face mask pressure;responsively issuing controller signals to adjust blower pressure provided by one or both of the inhalation blower and the exhalation blower to counter a face mask pressure drop during inhalation, and to counter a face mask pressure increase during exhalation, while maintaining a net positive face mask pressure with respect to ambient air pressure.

13. A method for setting face mask breathing air pressure of a closed-circuit rebreather (CCR), wherein the CCR includes a face mask, a compressed gas cylinder and a carbon dioxide (CO2) absorber, the method comprising executing, by an automated controller, steps including:receiving sensor signals from one or more pressure sensors and / or flow meters indicative of user respiration and of face mask pressure; andresponsively issuing controller signals to adjust blower pressure provided by one or both of the inhalation blower and the exhalation blower to counter a face mask pressure drop during inhalation, and to counter a face mask pressure increase during exhalation, while maintaining a net positive face mask pressure with respect to ambient air pressure.

14. The method of claim 13, wherein the controller signals to adjust blower pressure, to counter a face mask pressure drop during inhalation, are issued by the controller to the inhalation blower to increase the inhalation blower speed, and / or to an inhalation shutter to open, permitting breathing air flow from the inhalation blower to the face mask and / or to the exhalation blower to decrease the exhalation blower speed, and / or to an exhalation shutter to restrict breathing air flow from the face mask to the exhalation blower.

15. The method of claim 13, wherein the controller signals to adjust blower pressure, to counter a face mask pressure increase during exhalation, are issued to the inhalation blower to decrease theinhalation blower speed, and / or to an inhalation shutter to restrict breathing air flow from the inhalation blower to the face mask, and / or to the exhalation blower to increase the exhalation blower speed, and / or to an exhalation shutter to open, permitting breathing air flow from the face mask to the exhalation blower.

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