US 3474783 A
Description (OCR text may contain errors)
Oct. 28, 1969 P. ULM N 3,474,783
RESPIRATORY MASK WITH EXHALATION VALVE v I HAVING ALTERNATE BIASING MEANS Filed Jan. 31. 1967 2 Sheets-Sheet 1 Oct. 28. 1969 P. ULMANN 3,474,783
RESPIRATORY MASK WITH EXHALATION VALVE HAVING ALTERNATE BIASING MEANS Filed Jan. 31, 1967 2 Sheets-Sheet 2 EXHALATION VALVE ON A IR INLET United States Patent 3,474,783 RESPIRATORY MASK WITH EXHALATION VALVE HAVING ALTERNATE BIASING MEANS Paul Ulmann, Bagnols-sur-Ceze, France, assignor to Commissariat a lEnergie Atomique, Paris, France Filed Jan. 31, 1967, Ser. No. 612,974 Claims priority, applicatiozrhFrance, Feb. 18, 1966,
Int. Cl. A62b 7 /02; F16k 15/14 US. Cl. 128142.3 Claims ABSTRACT OF THE DISCLOSURE The present invention is directed to an exhalation device for respiratory masks. It is known that a protective mask or respirator should allow the exhaled air to pass through an outlet valve as soon as the pressure within the mask exceeds the pressure of the surrounding atmosphere by a predetermined difference.
Two types of respiratory masks are in common use. In one type, which will be referred-to hereinafter as isolating masks, the face-piece is supplied with a respiratory mixture at a pressure which is distinctly higher than that of the surrounding atmosphere (the over-pressure being usually between 20 and 50 mm. H O) in order to prevent the penetration of toxic gases or dust particles from the atmosphere through the face-piece at any locations in which leak-tightness is faulty. In the second type of respiratory mask, or so-called filtering masks, the face-piece is supplied from the surrounding atmosphere through a filter cartridge and an inlet valve which opens under the action of the reduced pressure or partial vacuum which is developed within the mask as a result of inhalation by the wearer.
In order to prevent any waste of the respiratory mixture, the exhalation device of isolating masks must be calibrated so as to remain closed as long as the pressure within the mask does not exceed the pressure of the atmosphere by a few millimeters of water in addition to the supply overpressure. An exhalation device of this type would not be suitable for use in filtering masks inasmuch as it would induce considerable respiratory discom fort in these masks, in which the exhalation device must open as soon as the pressure inside the mask becomes higher than the ambient pressure. In'short, the devices which are designed for filtering masks are not suitable for isolating masks inasmuch as they would permit leakage of the respiratory mixture, and the devices for isolating masks are not comfortable for use under filtering conditions.
However, in a number of dilferent applications and especially in the nuclear industry, it often happens that the same operator is obliged either for safety reasons or flexibility of use to make use of a filtering mask on some occasions and an isolating mask on other occasions. Up to the present time, it was necessary either to change the face-piece or to utilize in all cases an isolating mask exhalation device, with the resulting difiiculties in breathing which are experienced by the wearer.
3,474,783 Patented Oct. 28, 1969 The present invention is intended to provide an exhalation device for a respiratory mask which can be supplied either from the surrounding atmosphere through a filter cartridge or with a respirable gas which is at overpressure with respect to said atmosphere. The invention is especially characterized in that the device comprises a canister fitted with a valve-seat for connecting the interior of the mask to the atmosphere, a valve which is elastically applied against the valve-seat with slight pressure, elastic means adapted to cooperate with the valve so as to exert thereon an additional force which tends to apply said valve against its seat and which is of suflicient intensity to balance said overpressure with respect to the surrounding atmosphere, and a mechanism for releasing said elastic means.
The invention also extends to masks which are fitted on the one hand with a device for supplying a respiratory mixture and a filter cartridge for supplying the mask from the surrounding atmosphere which can be empolyed alternatively through a suction device and, on the other hand with an exhalation deivce as hereinabove defined. The invention also consists in other arrangements which are preferably employed at the same time in conjunction with the preceding but which can be employed independ ently thereof.
A better understanding of the invention will be gained by consideration of the following description of one form of execution which is given by way of non-limitative example, reference being made to the accompanying drawings, in which:
FIG. 1 is a view in elevation of an exhalation device as shown in the isolated condition;
" FIG. 2 is a view of the device taken in cross-section on a plane which passes through its axis, the parts being shown in the position occupied for the purpose of operation with an isolating mask;
FIG. 3, which is similar to FIG. 2, shows the parts in the position occupied for the purpose of operation with a filtering mask;
FIG. 4 is a View in cross-section of the device of FIG. 1 with the top removed, a number of parts being only partly shown for enhanced visibility of other parts located beneath;
FIG. 5 is a detail view of the check valve and is intended to show the deformation to which said valve is subjected when in position and at rest within the device.
FIG. 6 is a view of a prior art mask showing the location of the exhalation device or valve.
The device which is shown in FIGS. 1 to 4 comprises a canister A in which is mounted a normally-closed valve B. The casing A comprises a cylindrical body 6 which is secured in leak-tight manner to a skirt 10 of the facepiece C by means of a fastening collar 8 (as shown in FIGS. 2 and 3) and a cover 12. Said cover has a cylindrical skirt and a convex base 14 pierced by a series of uniformly spaced apertures 16. The skirt is provided with a circular internal boss 18 for engaging the cover 12 within a channel 20 of the body 6.
The top face of the canister body 6 has a circular rib of rounded transverse section which constitutes a valveseat 22, said seat being adapted to surround a communication passageway between the interior of the face-piece C and the cover 12. The exhalation or outlet valve is formed by the combination of said seat 22 and a gate 24 which is composed of a stem 26 and a flat diaphragm 32. The stem 26 has a narrowed portion 28 which is stationarily fixed in a recess formed in a hub of the body which is joined to the peripheral portion by means of three arms 30. The arms 30 are adapted to retai a screen 34 which is placed between the diaphragm 32 and the interior of the face-piece C (as shown in FIGS. 2, 3 and 4).
The valve-seat 22 and recess in which the stem 26 is imprisoned have a relative axial location such that, when the gate 24 is in position, the diaphragm 32 is slightly deformed, as is apparent from FIG. which shows the amplitude a of the deformation. The natural elasticity of the material constituting the gate thus tends to apply said gate against the seat 22 with a force which can be of a very low order.
There are also fitted in the cover 12 elastic means which tend to increase the force with which the diaphragm 32 of the gate 24 is applied against its seat 22 (as shown in FIGS. 2 and 3). These means comprise a cup 36 provided in the central portion with three apertures for the passage of air to the surrounding atmosphere. The axial displacement of said cup 36 is guided by three rectilineal bosses 38 formed on the skirt of the cover 12 and disposed at an angle of 120 relatively to each other. A spiral spring 40 which is compressed between the bottom 14 of the cover 12 and the cup 36 serves to apply this latter against the periphery of the diaphragm 32.
The cup 32 is rigidly fixed by any suitable means such as the screws 44 which are shown in FIGS. 1 to 4 to a control ring 46 which is adapted to slide over the outer cylindrical wall of the skirt of the cover 12.
The L-shaped guide slots which are formed in the skirt of the cover 12 permit the sliding motion of the screws 44; when the ring 46 is oriented in such a manner that the screws 44 are placed in that portion of the slots 48 which is parallel to the axis (as shown in FIGS. 1 and 2), the spring 40 thrusts back the cup 36 towards the gate 24 and adds its tension to the elasticity of the gate so as to shut off the outlet valve. On the other hand, when the ring 46 is raised and oriented so as to lock the screws 44 in that portion of the guide slots 48 which is perpendicular to the axis, the spring 40 cannot produce action on the gate 24 (as shown in FIG. 3).
The operation of the device is apparent from the foregoing description and will therefore be discussed only in brief outline.
When the ring 46 is free (as shown in FIG. 2), the
spring 40 applies said ring against the edge of the dia phragm 32. The force exerted by the spring 40 which is added to the elasticity of the diaphragm is sufficient to maintain the outlet valve in the closed position as long as only the normal supply overpressure of the mask is exerted on the diaphragm. It is only when the overpressure produced by the breath exhaled by the wearer is higher than the normal overpressure that the outlet valve opens to release the exhaled air. When the wearer of the mask has to operate this latter as a filter, using filter cartridge 51 (FIG. 6) for example in order to switch from one point of supply of respiratory mixture 50 (FIG. 6) to another, it is merely necessary in that case to remove the ring 46 and to rotate this latter to a slight extent in order to lock it in position (as shovm in FIG. 3). The cup 36 which is maintained in the top position retains the spring 40. The outlet valve is then free and the diaphragm 32 rises in the case of very low values of overpressure within the mask with respect to the ambient pressure, thereby preventing any difliculty in breathing. Moreover,.the diaphragm 32 is capable of reversal (position shown in chain-dotted lines in FIG. 3) in order to permit high flow rates.
What I claim is:
1. An exhalation device for respiratory masks, comprising a canister, a valve-seat in said canister forming a passageway connecting the interior of the .mask to the atmosphere, a valve elastically applied against said seat with slight pressure, resilient means cooperating with said valve to exert thereon an additional force applying said valve against its seat, mechanism for releasing said resilient means and freeing said valve therefrom, said resilient means being a spring interposed between said canister and a cup bearing on said valve, said bearing cup being rigidly fixed to a control ring slidably mounted on the outer wall of the canister said releasing mechanism locking said ring on said canister in a position in which said cup does not bear on said valve.
2. A device in accordance with claim 1, said cup and said ring being coupled by screws passing through L- shaped slots in said canister, said slots having a circular portion cooperating with said screws providing said release mechanism.
3. A respiratory mask comprising an exhalation device in accordance with claim 2, wherein said mask can be supplied either from the surrounding atmosphere through a filter cartridge or with a respirable gas which is at overpressure with respect to the atmosphere, and wherein said additional force is of sufficient intensity to balance said overpressure with respect to the surrounding atmosphere.
4. A respiratory mask in accordance with claim 3, wherein said mask comprises a device for supplying a respiratory mixture and a filter cartridge for supplying air from the surrounding atmosphere which can be employed alternately through a suction device whereby the interior of the mask can be connected either to the respiratory-mixture supply or to the filtered-air supply.
'5. An exhalation device for respiratory masks comprising a canister, a gas passageway in said canister con necting the interior of the mask to the atmosphere, a valve seat in said canister, a closure member cooporating with said valve seat to open and close said gas passageway in response to changes of gas pressure within the mask, means resiliently biasing said member to a position'in which said passageway is closed, supplementary biasing means movable between a first position in which said means resiliently act on said closure member to additionally bias said member to its closed position and a second position in which said means disengage said closure member, and manually actuable control means for moving said supplementary biasing means between said first and second positions and locking said supplementary biasing means in said second position.
References Cited UNITED STATES PATENTS 3,199,524 8/1965 Mitchell 137-529 XR FOREIGN PATENTS 74,330 6/ 1952 Denmark. 705,216 3/1954 Great Britain.
L. W. TRAPP, Primary Examiner U.S. Cl. X.R. l37529; 251176