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 Title: |
US4964404:
Breathing apparatus
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Stone, William C.; Derwood, MD 20855
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| Assignee: |
None
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| Published / Filed: |
1990-10-23
/ 1989-04-19
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| Application Number: |
US1989000340251
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| IPC Code: |
Advanced:
A62B 7/10;
B63C 11/24;
Core:
B63C 11/02;
more...
IPC-7:
A61M 16/00;
A62B 9/02;
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| U.S. Class: |
Current:
128/204.22;
002/002.5;
128/202.17;
128/204.26;
128/204.28;
128/204.29;
128/205.12;
128/205.13;
128/205.14;
128/205.22;
128/205.24;
128/205.28;
128/206.15;
Original:
128/204.22;
128/204.28;
128/204.29;
128/205.12;
128/205.13;
128/205.14;
128/205.17;
128/205.22;
128/205.24;
128/205.28;
128/206.15;
128/204.26;
002/002.5;
055/387;
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| Field of Search: |
128/205.11,205.12,205.13,205.14,205.15,205.17,205.22,205.24,204.18,204.22,204.26,204.28,204.29,201.25,201.28,206.15
002/2.1 R,2.1 A,2.5
055/387
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| Priority Number: |
| 1989-04-19 |
US1989000340251 |
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| Abstract: |
A mixed gas breathing apparatus reversibly switchable between open circuit and closed circuit systems. Three embodiments show three different levels of redundancy: nonredundant, bi-linear redundant and fully redundant. The counterlung minimizes the static lung loading and thus decreases breathing resistance. Manual control system is readily accessible and allows control of addition of the breathing gases.
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| Attorney, Agent or Firm: |
Marks Murase & White ;
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| Primary / Asst. Examiners: |
Eickholt, Eugene H.;
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| Maintenance Status: |
E3 Expired Check current status
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| INPADOC Legal Status: |
Show legal status actions
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| Parent Case: |
CROSS-REFERENCE TO RELATED APPLICATIONS
Reference is made to applicant's co-pending applications Ser. No. 07/340,250 entitled "BREATHING APPARATUS MOUTHPIECE" filed Apr. 19, 1989 and application Ser. No. 07/340,260 entitled "BREATHING APPARATUS GAS-ROUTING MANIFOLD" filed Apr. 19, 1989.
FIELD OF THE INVENTION
The present invention relates to portable life support systems used to sustain human respiration in locations where exposure to the environment would be fatal and in particular where there is a lack of immediate recourse to a safe-haven. These portable life support systems are free of safety umbilicals and larger environmentally controlled structures.
BACKGROUND OF THE INVENTION
Portable life support systems are used in a variety of situations in which the ambient environment around the user cannot be breathed either because of the lack of oxygen in usable form or because of the presence of substances which would have toxic effects if inhaled. These uses include extravehicular activity in space, scuba diving, deep off-shore diving work, use in contaminated atmospheres, use at high altitudes and the like.
The two fundamental architectures in the design of portable life support apparatus are open circuit and closed circuit systems. Open circuit systems, typified by the underwater diving system popularized by Jacques Cousteau, are the simplest, consisting of a compressed gas supply and a demand regulator from which the user breathes. The exhaust gas is ported overboard with each breath, hence the name "open" circuit. These systems are bulky and inefficient in that the oxygen not absorbed during each breath is expelled and wasted. Additionally failure of any component results in failure of the system.
Closed circuit systems, also known as rebreathers, make nearly total use of the oxygen content of the supply gas by removing the carbon dioxide generated by the user, and adding makeup oxygen or oxygen containing gas to the system when the internal volume drops below a set minimum level, or when the oxygen partial pressure drops below some pre-established setpoint.
These closed circuit breathing systems generally consist of a mouthpiece from which the user breathes and which is connected by means of two flexible impermeable hoses, one to remove the exhaled gas and the other to return the processed gas to a means for removing the carbon dioxide from the breathing gas, replenishing metabolized oxygen, and providing for makeup gas volume with a breathable gas to maintain system volume during descent as the gases within the breathing circuit are compressed. Such devices are usually provided with a series of checkvalves located near the mouthpiece such that gas flow within the breathing circuit is always maintained in a single direction. Oxygen addition to the system may be made by several means, most commonly by oxygen generators, such as the type disclosed in U.S. Pat. No. 2,710,003, to Hamilton et al., or the addition of oxygen or an oxygen containing gas, either through a constant mass flow orifice or by means of a manually operated or a sensor-controlled electronic valve.
Gas addition closed circuit systems may be one of two types, a pure oxygen version, which is limited to operating environments where the partial pressure of oxygen is less than two atmospheres, and a mixed gas version, normally used for underwater work at great depths. From a control standpoint, oxygen rebreathers are quite simple and require no active control. Mixed gas rebreathers, on the other hand, are considerably more complex. These were first pioneered in the late 1960's in an effort to solve the problems of narcosis at depths and to eliminate the oxygen toxicity problems which limit the safe diving depth of pure oxygen rebreathers.
The major deficiencies and problems existing with these known systems include a lack of redundancy or safety, limited duration or range, excess weight, high breathing resistance , and difficult manual operation.
A major leak anywhere in the breathing circuit of existing rebreathers leads to a subsequent flooding of the carbon dioxide removal system and therefore failure of the breathing apparatus. For operations conducted in locations where an immediate abort to a safe environment is impossible, such a failure could result in the death of the user.
When breathing in a closed circuit system, the exhaled breathing gas is held in a closed container, such as a breathing bag or a counterlung. Work is done when the gas is exhaled into, or inhaled from, the counterlung since surrounding environment is displaced as the counterlung is expanded. It has now been discovered that the work of breathing is dependent upon the user orientation angle and is directly related to static lung loading, which is the vertical distance, in centimeters of water, from the diver's or "user's" suprasternal notch, and the center of gravity of the inflated counterlung. Further, lung physiology prefers a slight positive pressure during inhalation, such as a static lung loading of between 0 to +10 centimeters of water. The present invention is the first to appreciate that known rebreathers with back-mounted counterlungs have negative static lung loadings and thus difficult inhalation characteristics while those that are chest-mounted have positive static lung loadings well in excess of +10 centimeters of water, and thus have hard exhalation characteristics. Furthermore, it has also been discovered that these known counterlungs are very sensitive to the user orientation angle due to the location of the center of gravity of these counterlungs.
In the prior art manual bypass valves, which permit the user to manually add either oxygen or an oxygen containing gas to the breathing circuit in the event of failure of the automatic valves, if present, have been placed on the body of the rebreather. For the case of a back-mounted rebreather, such as that shown in U.S. Pat. No. 3,710,553, these valves require an awkward reverse reach in order to operate them.
It is a primary object of the present invention to provide a mixed gas breathing apparatus switchably operable between open circuit and closed circuit modes and with different levels of redundancy for this apparatus; non-redundant, bi-linear redundant, and fully redundant.
It is a further object of the present invention to provide a counterlung for the breathing apparatus that minimizes the work of breathing wherein the static lung loading is between 0 to +10 centimeters of water.
A still further object of the present invention is to provide a manual control system which is compact and easy to reach. Such ease of use and ready accessibility is essential in an emergency where the user is apt to panic when faced with the possibility of death.
SUMMARY OF THE INVENTION
The present invention provides an integrated, improved mixed gas breathing apparatus which solves the specific problems described above. This mixed gas breathing apparatus is reversibly switchable between an open circuit and a closed circuit system. In three different embodiments of this invention, the breathing apparatus has different levels of redundancy. The first embodiment, as depicted in FIG. 1, is a non-redundant breathing apparatus. The second embodiment, depicted in FIG. 12, is a redundant bi-linear breathing apparatus. While, the third embodiment, depicted in FIG. 14, is a fully redundant breathing apparatus.
The breathing apparatus of the present invention is preferably equipped with twin, split counterlungs comprising the frontal portion of a vest worn by the user. An integral buoyancy compensator comprises the back side of the vest. The counterlungs are independently attached by means of flexible waterproof hoses to independent carbon dioxide removal systems in gas sensor banks for automated control of the oxygen concentration in each half of the system.
The breathing apparatus is equipped with two mouthpieces, for the bi-linear redundant and fully redundant systems, or one mouthpiece for the non-redundant system, connected by means of flexible waterproof hose to the independent split counterlungs, from which the user breathes and which can be made to function in either the open circuit or closed circuit mode. Each mouthpiece is equipped with directional check valves which control the direction of gas flow through the closed circuit system.
When used for diving, or under other pressure conditions, upon decent to greater depth or increased pressure, and in subsequent collapse of the counterlungs, inhalation demanded is satisfied through the mouthpiece, which contains an internal second stage open circuit diaphragm and gas addition valve which together comprise the automatic diluent system. The second stage diluent gas addition valve is equipped with an adjustable in-line flow restricter which permits the user to adjust the pressure drop required to trigger an opening of the valve and, should the need arise, completely close off the flow, thus providing diluent shut-off capability within easy, quick reach of the user.
Auxiliary manual control systems are provided for each closed circuit breathing circuit in compact cases which are affixed to the front of the vest. Each manual control system permits the user to manually add both oxygen and a diluent gas, as well as to shut-off the flow of oxygen to the breathing circuit from the automatic oxygen control system in the event of a malfunction in the automatic control system. Each manual control system output is connected by means of a single flexible low pressure line to the downstream side of the exhalation hose from each respective mouthpiece at its junction with the exhalation counterlung.
Two manifold blocks, mounted at the shoulder line of the vest, permit inhalation and exhalation lines from each mouthpiece, and automatic and manual gas addition lines, to be cross routed to the opposite system's carbon dioxide removing and gas control systems in the event of a malfunction.
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| Family: |
None
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First Claim:
Show all 42 claims |
I claim:
1. A breathing apparatus comprising:
- a first circuit comprising:
- a carbon dioxide removal device;
- said first circuit being operatively connected to enable gas to flow from said mouthpiece to said counterlung and said carbon dioxide removal device and back to said mouthpiece; and further comprising:
- a second circuit comprising:
- a supply of breathable gas normally automatically supplied to said first circuit over a first path;
- a manual override system for manually interrupting said automatically supplied breathing gas; and
- a second path for selectively manually connecting said supply of breathable gas to said first circuit through said manual override system for selectively manually admitting breathable gas into said first circuit.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 31 U.S. patent(s) that reference this one
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