US2403991A - Breathing apparatus - Google Patents

Description

y 16,1946; c. ,1. MURPHY pi-AL 2,403,991

BREATHING APPARATUS Filed Dec. 6, 1939 5 Sheets-Sheet l Mg? N a N 9 s H 3 n) a) I; Q,

WITNESSES v INVENTORS.

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July l6, 1946- c. J. MURPHY ETAL BREATHING APPARATUS Filed Dec. 6, 1939 3 Sheets-Sheet 3 INVENTORJ' Patented July 16, 1946 BREATHING APPARATUS Cornelius J. Murphy and William P. Yant, Pittsburgh, Pa., assignors to Mine Safety Appliances Company, Pittsburgh, Pa., a corporation of Pennsylvania Applicationllecember 6, 1939,Serial No. 307,783

This" invention relates to breathing apparatus, and more particularly to the self-contained type 3 Claims. (Cl. 128-191') in which pure oxygeni may be supplied. to the breathing circuit. 1 At very high altitudes, such as those encountered by aviators, the rarified air does not supply sufficierit oxygen to sustain human life. Therefore, it is customary to furnish aviators who are going to fly at such'heights with breathing apparatus connected to a supply of oxygenthat makes up for the deficiency inthe air. There are several types of breathing apparatus for this purpose, one of the mosteconomical being the demand' type in which oxygenenters the breathing tube only during inhalation. 'This type of apparatus'is sometimes constructed so that part of the unpurified exhaled air'may be rebreathed in order that the supply of pure oxygen will not be exhausted as quickly as otherwise. Nevertheless, there is still a waste of oxygen because the larger share of that inhaled but not consumed by the .body is lost with the exhaled air, whereby the service time of a given supply of oxygen is materially decreased.

In constructing the breathing apparatus define'dherein there were a number of special problems that had to be solved. It was necessary that the apparatus he self-contained and operative at variable atmospheric pressures and at altitudes from 15,000 to 30,000 ieet where the temperature is as low asminus 25 C. Such low temperatures cause condensation of moisture in the exhaled air resulting heretofore infreezing of the valve systerns of breathing apparatus. To be acceptable, the apparatus must be capable of furnishing oxygen while ascending from 15,000 to 30,000 feet, remaining at the higher altitude for two hours, and then descending to the 15,000 foot elevation. All that time the apparatus must be capable of supplying sufficient oxygen to support extreme physical exertion and to compensate for the psychological effects of the low atmospheric pressures. It likewise must not be uncomfortable to wear nor interfere with normal operation of a plane or gun, even though the seat is arranged to swing around in a complete circle. Satisfactory breathing apparatus must also be operative inany position.

It is among the objects of this invention to provide breathing apparatus which is especially suitable for high altitudes, in which substantially no oxygen is wasted during normal operation, which contains an air-purifying canister that can be quickly removed and replaced without inter- 2 fering with breathing, and which is simple in construction and operation.

Another object of this invention is to'provide breathing apparatus which operates on the demand principle but which is simplified in'that the apparatus requires a single breathing 'tube for operation and includes a simplified valve arrangement and one which is adaptable especially for operation at low temperatures.

A further object is to provide breathing apparatus which is adaptable to use with many types of canisters containing the chemicals for purifying exhaled air.

A still further object of this invention is to provide breathing apparatus including an auxiliary source of oxygen connected to the breathing circuit in such a manner that the valve system necessary for controlling the supply of oxygen is operable at extremely low temperatures.

In accordance with this invention a face-piece, covering the nose and mouth or the mouth alone, is connected by a breathing tube to a breathing chamber or bag to which pure oxygen issupplied from a suitable container. The bag, is provided with a type of valve that admits more oxygen to it only after the oxygen in the bag has been depleted to a certain extent by consumption in the body during the course of respiration. The wall of the breathing tube is provided with a pair of spaced valves that are adapted to be opened by an air-purifying canister when itsinlet and outlet are associated with the valves. The canister contains a suitable chemical for removing the carbon dioxide from the exhaled air and liberating oxygen. To prevent the exhaled air from passing around the canister instead of through it, the tube is provided with a check valve between the other two valves. The exhaled air in passing through the canister reacts with the chemical therein and liberates oxygen which passes on to the breathing bag. Consequently, the oxygen that is exhaled is not lost but is reinhaled so that less new oxygen from the container is required. During inhalation the resistance of the canister to air flow through it causes the check valve in the breathing tube to open and permit the air to pass around the canister. With this construction only one breathing tube is required.

When the air-purifying canister needs replacing because of utilization of its chemical it is removed and the two valves that were held open by it are closed, preferably automatically by springs. Outside air, whether impure or merely deficient in oxygen, is thus prevented from entering the breathing tube while the canister is removed.

' 3 During the short period required for replacing the canister the wearer breathes oxygen directly from the breathing bag and exhales around the edges of the face-piece, because the check valve in the breathing tube prevents him from exhaling back into the bag.

If desired, the breathing tube valves that are opened by the canister may be omitted as they do not affect the operation of the apparatus while the canister is in place. In one form of the invention the exhaled air, that is warmed considerably by chemical reaction in the canister, passes around the above-mentioned breathing bag valve to prevent any tendency for that valve to freeze in very cold atmospheres.

The invention is illustrated in the accompanying drawings in which Fig. 1 is a front View, partly in section, of a portion of my breathing apparatus; Fig. 2 is a fragmentary front view of the lower portion of the canister receptacle and breathing tube connected thereto; Fig. 3 is a fragmentary view showing the canister removed and the valves closed; Fig. 4 is a front view of the breathing bag and oxygen container that are connected to the breathing tube; Fig. 5 is an end view of the breathing bag with the oxygen container removed; Fig. 6 is a front view, partly broken away, of a modification of the breathing bag assembly; and Fig. '7 is a vertical section thereof taken on the line VIIVII of Fig. 6.

Referring to the drawings, a face-piece I (Fig. 1) of any suitable form is connected by a breathing tube 2 to a breathing bag 3 shown in Figs. 4 and 5. This bag is connected by an admission valve 4, a pressure-reducing valve 6 and a pipe I to the main valve 8 of an oxygen cylinder 9. This cylinder is also provided with a by-pass valve II that is connected by a pipe l2 directly to the breathing tube for by-passing oxygen around the bag in case of emergency. Between the oxygen cylinder and reducing valve, pipe 7 is provided with a pressure .gauge l8. The admission valve 4 is normally closed by a spring biased plunger I 4 that extends toward a bumper plate I6 on the opposite side of the bag which engages the plunger and thereby opens the valve whenever the bag becomes nearly deflated by consumption of oxygen by the body. Consequently, oxygen is supplied to the bag only at periodic intervals and is withdrawn therefrom only by the inhalations of the wearer of the face-piece.

It is a feature of this invention that the oxygen contained in the exhaled air is retained in the breathing apparatusand rebreathed so that it will not be wasted but will conserve the oxygen in the oxygen cylinder. Accordingly, a canister receptacle 2! is mounted on a pad '22 to which straps 23 are connected for harnessing this part of the breathing apparatus to the body of the wearer. The breathing tube from the face-piece leads directly to the top of this receptacle with which it communicates through a passage 25 in their adjoining walls. From this passage the breathing tube extends laterally to the side of the receptacle down which a flexible portion of the tube extends to another laterally extending portion below the receptacle. Hinged to the bottom of the canister receptacle is a cover 26 that is rigidly connected to the breathing tube below its central portion and with which the interior of the receptacle communicates through a passage 2?. The breathing tube continues on from cover 26 t0 the breathing bag.

To close passages 24 and 21 between the tube and canister receptacle when the latter is empty,

inlet and outlet valves 28 and 29 are mounted in the tube adjacent the two passages. These two valves are biased toward each other toward closed position by means of coil springs 3i encircling their stems 32 which are slidably mounted in guides 33 in the breathing tube. Each valve has an irregularly shaped portion 34 that extends substantially through the passage when the valve is closed and which does not close the passage when the valve is open. The air-purifying canister '36 that is placed in the canister receptacle contains a chemical suitable for removing carbon dioxide from the exhaled air and liberating oxygen. The canister has an inlet tube 31 at its upper end and an outlet tube 38 at its lower end which engage projecting portions 34 of the valves and force them inwardly so that the valves are unseated, as shown in Fig. 1. The inlet and outlet tubes of the canister are encircled by sealing gaskets 39 that are pressed against the walls of the passages. Thus, while the canister is in operative position the two Valves are held open by it so that exhaled air will pass through it and liberate oxygen that passes on to the breathing bag to add to the oxygen furnished by the oxygen cylinder. Exhaled air is prevented from shortcircuiting around the canister through the breathing tube by an inhalation check valve 4| mounted in the tube adjacent outlet valve 29. During inhalation this check valve is drawn open so that air can travel directly from the breathing bag to the face-piece through the breathing tube without having to pass through the canister which offers considerable breathing resistance.

When the chemical in the canister becomes spent so that a new canister is required, cover 26 is unlatched from the canister receptacle and swung downwardly to the position shown in Fig. 3. The moment this happens the pressure of the canister against valves 28 and 29 is released and they are closed by their springs to seal the breathing tube against the outside atmosphere. During the short period that expires while the old canister is being removed and replaced by a new one, the wearer inhales directly from the breathing ba as before, but exhales between the edges of the face-piece and his face. When the receptacle cover is closed on the new canister, the inlet and outlet tubes of the latter again force valves 28 and 29 open and. reestablish the normal selfcontained breathing circuit.

Directly below the face-piece the breathing tube is provided with a shut-off valve 42 which is used when the apparatus is being flushed out. That is, the wearer'inhales, closes this valve so that air can neither enter nor leave the breathing tube, and exhales directly into the atmosphere by lifting the face-piece. The valve is then opened and this process repeated a couple more times.

It will be seen that by utilizing check valve 4| during exhalation to direct exhaled air through the canister, and the breathing resistance of the canister during inhalation to by-pass purified air around the canister, only one breathing tube serves for both inhalation and exhalation. This simplifies the construction and makes the apparatus less cumbersome which is highly desirable for aircraft use.

Figs. 6 and 7 show a modified embodiment of the breathing bag assembly in which the collapsible breathing bag 5| is mounted in a metal box 52 to the back side of which the adjoiningside of the bag is secured as shown in Fig. 7..

Oxygen is supplied to the bag from a cylinder 53 disposed outside of the box and having a main valve 54 connected by a pressure reducing valve 56 inside of the box to an admission valve 51 communicating with the inside of the bag. The reducing valve is provided with a chamber 58 in which a lever 59 is pivotally mounted at one end. The opposite end of the lever is pivotally connected to the lower end of an upright rod 6| suspended from the top of a bellows member 62. Oxygen enters chamber 58 through a passage 63 when slidable valve member 64 is forced away from the inner end of the passage by a coil spring 65, and the passage is at all times in communication with a pressure gauge 61 through a tube 58. As the pressure in chamber 58 increases it expands the bellows and lifts rod 61 which swings the projection 69 on top of lever 59 against valve member 64, thereby forcing it inwardly against the inner end of valve passage 63.

The opposite side of chamber 58 is connected by a tube H to a valve chamber I2 (Fig. 7) in an admission valve projecting inwardly from the back side of box 52. This valve is normally closed by a spring pressed valve member 14 having a plate 16 on its outer end. When this valve member is moved inwardly it uncovers a port 11 that connects chamber 12 with an inner chamber 78 that is formed partly by a collapsible bellows member 19, This inner chamber is connected by a tube Bl to the interior of the bag.

As in the first embodiment, oxygen is admitted to the bag from the cylinder only when required, and likewise it is admitted only when the bag collapses a predetermined amount. Accordingly, the free side of the bag carries a metal disc 82 to which the lower end of a triangular metal plate 83 is pivotally connected. The upper end of this plate is pivotally supported from a bracket 84 connected to the top of the box. The upper portion of this plate is provided centrally with an opening in which a threaded sleeve 86 is secured which contains a screw 8! that is adjustable axially therein. When the bag collapses a predetermined amount the inner end of this screw engages end plate 16 on the admission valve and thereby forces valve member M away from port 1'! to allow oxygen to escape from the reducing valve chamber into tube 8| and the bag.

It is a feature of this embodiment of the invention that the breathing tube 2 (Fig. 6) which connects the bag with the face-piece is connected to the top of the box by a coupling 88 that opens into a jacket 89 encircling the major portion of admission valve 51. From an opening in the bottom of the jacket a tube 9| leads downwardly or shut in cold atmospheres, such as in high altitude aircraft use. This desirable result is accomplished because the exhaled air is warmed considerably in passing through air-purifying canister 36 of Fig. l by the chemical reaction therein, and this warm air flows in jacket 89 around the admission valve.

According to the provisions of the patent statutes, we have explained the principle and mode of operation of our invention and have illustrated and described what we now consider to represent its best embodiments. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. The combination with a face-piece, a breathing chamber, a breathing tube connecting said chamber and face-piece, and an oxygen container for supplying the chamber with oxygen, of an airpurifying canister provided with an inlet and an outlet, a pair of spaced valves mounted in the wall of said tube and adapted to be opened by said canister inlet and outlet when associated therewith, means detachably connecting the canister to said valves, and an inhalation check valve disposed in said tube between said pair of valves adjacent the canister outlet valve.

2. The combination with a face-piece, a breathing chamber, and an oxygen container for supplying the chamber with oxygen, of a breathing tube connecting said chamber andface-piece and having two laterally spaced substantially parallel portions connected by a flexible portion, a canister receptacle disposed between said spaced portions of the tube and rigidly connected to the wall of one of them, said wall and receptacle being provided with a communicating passage, said receptacle having a removable cover rigidly connected to the wall of the other of the spaced portions of the tube, said cover and wall being provided with a communicating passage, a pair of spring biased valves mounted in the tube for closing said passages, an air-purifying canisterremovably mounted in said receptacle and provided with inlet and outlet portions that open said valves when said cover is closed, and an inhalation check valve disposed in said breathing tube between said pair of valves.

3. Breathing apparatus comprising a facepiece, a breathing chamber, a breathing tubeconnecting said chamber and face-piece, an oxygen container for supplying the chamber with oxygen, the wall of said tube being provided with a pair of longitudinally spaced openings, an air-purifying canister provided with an inlet and an outlet communicating with said openings, and an inhalation check valve disposed in said tube between said openings adjacent the canister outlet opening.

CORNELIUS J. MURPHY. WILLIAM P. YANT.

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