Oxygen Mask

The present invention relates to an oxygen mask.

Most oxygen masks have a face piece to cover the mouth and nose, a one-way exhalation valve and a one-way inhalation valve connected to a supply of oxygen, and optionally a second one-way inhalation valve connected to ambient air. The oxygen supply is normally set at a predetermined "full flow" rate which ensures that there is always sufficient oxygen being fed into the mask through the inhalation valve throughout both the inhalation and exhalation cycle of the lungs. On breathing in, oxygen mixed with ambient air (either from the second inhalation valve or externally mixed with oxygen) is drawn into the lungs, and then the lungs exhale the gas through the exhalation valve. However during exhalation of the lungs, oxygen under pressure still enters the mask through its one way inhalation valve, but this means that unconsumed oxygen is also exhausted through the exhalation valve without ever entering the lungs of the user. This results in a waste of oxygen.

It has been attempted to connect the oxygen to the inhalation valve through an expandable bladder in order so that the bladder fills during the exhalation of the lungs and then contracts during the inhalation by the lungs, thereby reducing the amount of oxygen entering the mask during the exhalation of the lungs and so reducing waste of oxygen. However the force required to inflate the bladder results in a positive pressure of oxygen at the inhalation valve even during the exhalation of the lungs, and oxygen is still wasted through the exhalation valve without ever entering the lungs of the user. This again results in a waste of oxygen.

On mountaineering expeditions, this waste of oxygen can lead to a shortage of oxygen which can result in a mission being aborted or put the lives of the mountaineers at risk.

The invention seeks to provide a solution to this problem.

According to the present invention there is provided an oxygen mask comprising:

a) A mask face piece to cover the nose and mouth of a user, said face piece having at least one one-way inhalation valve, and an one-way exhalation valve, b) A chamber having an inlet port connectable to an adjustable supply of oxygen, and outlet port, and apertures in the chamber wall connecting the inside of the chamber to ambient air, and c) A conduit connecting the chamber outlet port to a face piece inhalation valve, in use oxygen enters the chamber displacing ambient air in the chamber through the apertures during the exhalation cycle of the user's lungs, and oxygen is drawn out of the chamber through the conduit and through an inhalation valve during the inhalation of the lungs.

Preferably, the supply of oxygen is adjusted such that the amount of oxygen being consumed during the inhalation cycle is substantially equal to the capacity of the chamber.

In one emobodiment the chamber includes a bag connected to the inlet port and outlet port which inflates during the exhalation cycle displacing air out through the apertures, and collapses during the inhalation cycle drawing air in through the apertures into the chamber. Preferably the mask face piece has an one-way inhalation valve connected to the conduit and a second one-way inhalation valve connected to ambient air.

In another embodiment the chamber has an inlet port and outlet port at one end and the apertures at the other end, and said chamber fills with oxygen and mixes with and displaces ambient air during the exhalation cycle of the lungs, and mixed oxygen and air exits the chamber and is drawn into the mask face piece during the inhalation cycle of the lungs, whilst being displaced with ambient air through the chamber apertures.

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows a schematic view of a first embodiment during the inhalation of the lungs,

Figure 2 shows a schematic view of a first embodiment during the exhalation of the lungs,

Figure 3 shows a schematic view of a second embodiment during the inhalation of the lungs, and

Figure 4 shows a schematic view of a third embodiment during the exhalation of the lungs.

Referring to Figures 1 and 2 there is shown an oxygen mask 1. Mask 1 has a mask face piece 2 to cover the nose and mouth of a user. Face piece 2 may be of a type known in the art. Face piece 2 has a first one-way inhalation valve 3, a second oneway inhalation valve 4 connected to ambient air, and an one-way exhalation valve 5. One way valves 3, 4 and 5 may be circular rubber discs which seal against and lift off a peripheral seating formed by the mask piece as is known in the art.

A transparent plastics tubular chamber 6 is provided. Chamber 6 has an inlet port 7 connected by a tube 8 to an adjustable supply of oxygen "X", and an outlet port 9. A conduit 10 connects the chamber outlet port 9 to the first mask inhalation valve 3. Inlet port 7 and outlet port 9 are at one end of tubular chamber 6. At the other end of chamber 6 are a plurality of apertures 11 in the chamber wall connecting the inside of the chamber to ambient air (a single aperture could be provided).

An inflatable bag 12 of non-elastic material is connected to the inlet port 7 and outlet port 9.

In use, during the exhalation cycle of the user's lungs, oxygen (dots) enters the bag 12 in chamber 6 displacing ambient air (dashes) in the chamber through the apertures 11 and so inflates the bag as shown in Figure 2. Whilst exhaling the pressure in mask face piece 2 is positive so closing the first and second inhalation valves 3 and 4, and air from the lungs is expelled through the exhalation valve 5.

During the inhalation cycle of the user's lungs, oxygen is drawn out of the bag 12 in chamber 6, through the conduit 10 and through first inhalation valve 3 as the

pressure in the mask piece 2 is negative. Also ambient air is drawn in through second inhalation valve 4 to mix with the oxygen before it enters the user's lungs. At the same time bag 12 collapses drawing ambient air into the chamber through apertures 11 as shown in Figure 1.

The supply of oxygen can be adjusted such that the amount of oxygen being consumed during the inhalation cycle is substantially equal to the capacity of the chamber so that the bag almost fills and collapses. The transparent chamber allows the user to check this.

The ability of the bag to store and deliver oxygen during inhalation means that the user always has oxygen on demand, but with the oxygen supply adjusted correctly, there is no positive pressure leaking oxygen into the mask face piece during the exhalation cycle so no oxygen is wasted.

Referring to Figures 3 and 4 there is shown an oxygen mask 21. Mask 21 has a mask face piece 22 to cover the nose and mouth of a user. Face piece 22 may be of a type known in the art. Face piece 22 has a first one-way inhalation valve 23, and an one-way exhalation valve 25. One way valves 23, 25 may be circular rubber discs which seal against and lift off a peripheral seating formed by the mask piece as is known in the art.

A transparent plastics tubular chamber 26 is provided. Chamber 26 has an inlet port 27 connected by a tube 28 to an adjustable supply of oxygen "X", and an outlet port 29. A conduit 30 connects the chamber outlet port 29 to the first mask inhalation valve 23. Inlet port 27 and outlet port 29 are at one end of tubular chamber 26. At the other end of chamber 26 are a plurality of apertures 31 in the chamber wall connecting the inside of the chamber to ambient air (a single aperture could be provided).

In use, during the exhalation cycle of the user's lungs, oxygen enters chamber 26 displacing ambient air (dashes) in the chamber through the apertures 31 whilst mixing with ambient air to fill chamber 26 with oxygen (dots) and ambient air mixture as shown in Figure 4. Whilst exhaling the pressure in mask face piece 22 is positive

so closing the first inhalation valve 23, and air from the lungs is expelled through the exhalation vale 25.

During the inhalation cycle of the user's lungs, oxygen and ambient air mixture is drawn out of chamber 26, through the conduit 30 and through first inhalation valve 23 as the pressure in the mask piece 22 is negative. At the same time ambient air is drawn into the chamber 26 through apertures 31 as shown in Figure 3.

The supply of oxygen can be adjusted such that the amount of oxygen being consumed during the inhalation cycle is substantially equal to the capacity of the chamber so that the chamber almost fills without oxygen escaping out of the apertures 31 and then empties of oxygen and ambient air mixture.

The ability of the chamber to store and deliver oxygen during inhalation means that the user always has oxygen on demand, but with the oxygen supply adjusted correctly, there no positive pressure leaking oxygen into the mask face piece during the exhalation cycle so no oxygen is wasted.

The invention has applications in mountaineering as well as medical, aviation and other applications.

The invention may take a form different to that specifically described above.

Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

TOMKINS & CO.