US 2830584 A
Description (OCR text may contain errors)
April 1958 F. HOLLMANN ETAL 2,830,584
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April 15, 1958 F. HOLLMANN ETAL 2,830,584
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April 1958 F. HOLLMANN EIAL 2,830,584
RESPIRATOR 5 Sheets-Sheet 5 Filed Dec. 9, 1953 United States Patent RESPIRATOR Franz Hollmann, Ernst Warncke, and Karl Friedrich Miillering, Lubeck, Germany, assignors to Firma Drag'erwerk, Heinr. & Bernh. Drager, Lubeck, Germany v Application December 9, 1953, Serial No. 397,067 Claims priority, application Germany December 15, 1952 3 Claims. (Cl. 128-443) This invention relates to respirators, and in particular to the supply of air thereto.
Respirators are well known which comprise either half or full face masks into which the fresh air is supplied through a hose. Such devices are preferably used to protect the wearer from dust, or against inhaling harmful gases. In respirators of this type the entire amount of fresh air supplied is introduced directly into the mask. The excess fresh air escapes with the exhaled air through exhaust valves, or through a free opening to the outside.
The supply of fresh air in such devices is such that the wearer will not find it difficult to breathe. Consequently, the amount of fresh air supplied is greater than the average amount of air inhaled, and therefore the maximum amount of air required by the wearer is supplied also.
Since this maximum requirement of air generally only occurs when the wearer performs heavy work, the air supply exceeds the normal requirement by only a small amount.
It has also been proposed to insert a respirator bag into the fresh air supply line which fills up during the exhaling' phase, and from which the maximum air requirement is drawn during the inhaling phase. In such a device the amount of air supplied can be less than the maximum amount of air required. But even under these circumstances the amount of air supplied is still often larger than the amount required for breathing, particularly since the air supply is continuous while breathing is an intermittent process.
The fresh air supplied in excess diffuses throughout the entire space within the mask, and consequently comes in contact with the part of the face covered by the mask. This is particularly undesirable when the air is dry, as is the case when, for example, the fresh air supply is expanded compressed air. Fresh air which istaken from a compressed air line under pressure of 6 atm. gauge, generally has a moisture content of only The dry air passes over that portion of the face .coveredby the mask, particularly the lips and dries out the skin. The absorption of water vapor by this dry air from theinterior of the mask results in a relatively sharp cooling effect upon the portions of the face in question, and may consequently lead to colds.
The objects of the instant invention are to avoid the disadvantages of these known respirators. The invention relates to a breathing mask for supplying fresh air and comprises anair supply line leading intoan antechamber which .in turn is connected to the interior of the mask as well as" being in communicationwiththe outside air. With this structure only that amount of fresh air is fed into the interior of the mask as is required for breathing, while the excess amount of air passes directly from the antechamber to the outside, without coming in contact with the face. Therefore, the wearer of the respirator takes from the stream of fresh air passing through the antechamber only that amount which is necessary to fill his lungs. Only that amount of air passes into the interior of the mask.
A structure of the antechamber may be of various types. A simple embodiment comprises an antechamber which is a continuation of the fresh air supply line. The
fresh air supply line may continue longitudinally and end on the outside, so that the fresh air is so-to-say led past the actual interior of the mask and only that amount of fresh air enters the interior of the mask as is aspirated by the wearer. The antechamber can take the form of a straight or bent tube, or a straight or bent hose, which passes through the interior of the mask and is provided with openings, preferably lateral openings, which communicate with the interior of the mask.
In another embodiment the antechamber isformed by partitioning off a portion of the interior of the mask. However, the antechamber may also be provided on the outside of the body of the mask proper.
In all cases, it is important that a chamber is inserted before the mask itself, through which the fresh air supply passes, but the chamber may have various shapes.
In order to permit a more economical use of fresh air, the antechamber may be relatively large. This results in a further advantage in that when the air supply is small the wearer will not inhale outside air into his lungs, even though under maximum consumption the fresh air supply is not sufficient. Since the antechamber is relatively large, under maximum requirement conditions the contents of the antechamber pass through the inhaling passages first while outside air follows through the exhaust openings of the fresh air supply line. The antechamber is of such size that it contains enough fresh air to cover the maximum requirements with any given amount of fresh air supply. The smaller the amount of fresh air supplied, the larger should be the antechamber. The structure of the antechamber is also such that the openings connecting the antechamber with the outside air are as remote as possible from the opening connecting the antechamber with the interior of the mask. This structure assures that fresh air is aspirated first out of the antechamber.
I The antechamber may be removable.
In order to avoid the formation of an undesirable excess pressure in the interior of the mask, the opening between the antechamber and the outside air is larger than the opening, or the sum of the openings, leading from the antechamber into the interior of the mask.
If the wearer is in a comparatively little harmful atmosphere, for example, in dusty air, the opening leading to the outside, i. e. the opening between the antechamber and the outside can remain open. If the antechamber is small, outside air may be pulled into the chamber whenever the wearer takes an especially deep breath. In order to avoid the entrance of outside air even under those conditions, the opening between the antechamber and the outside is provided with a check valve which opens when the flow of air therethrough is toward the outside and which is responsive preferably to very small rates of flow. Such a structure is chosen, for example, if the outside air contains carbon monoxide.
In order to reduce theresistance to exhaling, the inner wall of the mask is provided with one or more exhaust valves. The opening pressure of the exhaust valves, the openings of the fresh air supplylines into the interior of the mask, and the exhaust openings are adjusted by the pressure inside the mask during the exhaling phase and are dependent upon the pressure of the fresh air supply, so that the exhaled air is reliably prevented from reentering the antechamber, and all of the exhaled air passes through the exhaust valve to the outside.
The entrance opening for the fresh air supply into the antechamber is provided with a check valve which opens in the direction of the flow of fresh air. Another check valve is provided between the antechamber and the mask, which check valve opens into the interior of the mask.
The means by which the objects of the invention are obtained are described more fully withrespect to the accompanying drawings, in which:
Figure 1 is a cross-sectional view through a mask for covering the lower portion of the face;
Figures 2 to 5, inclusive, are views similar to Figure 1, each showing, respectively, a modified form of the invention;
Figure 6 is a cross-sectional view of a mask for covering the full face according to the invention;
Figure 7 is a cross-sectional view diagrammatically showing a further modified form of a mask as in Figure 1; and
Figure 8 is a cross-sectional view on the line 88, Figure 7. p
In the embodiment shown in Figure 1, an antechamber 3 is formed by mask body 1, made of sheet aluminum, and sheet metal partition insert 2. The sheet metal body 1 is provided with a rubber sealing edge 4. Connecting fitting 5 has corrugated hose 6 connected thereto, and communicates with chamber 3. A relatively small opening 7 is. provided in partition 2 adjacent the lower edge thereof and offset from the path of air flowing from fitting 5. The chamber 3 communicates with the outside through opening 8 which is larger than opening 7; Mask body 1 is also provided with an exhaust valve 9. The fresh air flowing through hose 6 enters chamber 3 through fitting 5. When the wearer inhales, the air is aspirated through opening 7. When the wearer exhales, the used air can pass to the outside through exhaust valve 9.
The embodiment shown in Figure 2 differs from that in Figure 1 principally in that the antechamber 3 is formed by bent tube 10 which twice pierces the mask body 1. The passing fresh air is aspirated during the inhaling phase through lateral openings 11 in the bent tube.
Figure 3 shows a rubber mask 12 whose antechamber 13 is molded with the mask body and is formed by partition 14. This partition has an opening 15 which communicates with the inside of the mask. Opening 16 opens antechamber 13 to the outside sidewise of the mask. Connecting fitting 17 on the mask has a fitting 18 inserted therein, onto which the thin air supply hose 19 is fastened.
Figure 4 shows a rubber half face mask which has a rubber antechamber 21 attached to rubber mask body 20. The interior of antechamber 21, space 22, is communicated with the interior of the mask by opening 23. Antechamber 21, which is tubular in shape, has hose 24 fastened to it on one end, and has excess pressure valve 25 mounted upon the other end. The excess pressure valve prevents outside air from being aspirated in a direction opposite to that of the flow of fresh air whenever the wearer takes an especially deep breath.
The embodiment shown in Figure 5 is essentially similar to that of Figure l. Check valve 26 is mounted across exhaust opening 8, and another check valve 27 is mounted across air supply line stud 5. Check valve 27 prevents exhaled air from being forced back into hose 6 whenever the wearer of the respirator exhales strongly. Check valve 26 prevents outside air from being drawn into the mask when the wearer takes a deep breath.
Figure 6 shows a full face mask 28 comprising exhaust 4v valve 29, eye glasses 30 and sealing edge 31. Mask body- 28 has-a stud member 32 fastened onto it. An antechamber 33 is removably attached to the stud member by bolt 34 which engages the threaded portion 35 in a spider on stud 32. Fresh air enters through hose 36 and is exhausted through excess pressure valve 37. The antechamber is closed olf from the interior of the mask by intake valve 38. Valves 37 and 38 function as described for corresponding valves 26 and 27 in Figure 5.
In Figure 7 the face mask body 38 of this embodiment is only partially shown. The mask body 38 has an exhaust valve 39 fastened to it. Stud member 40, which is not shown in detail, has a relatively large tube or hose 41 fastened thereto which contains intake air supply passage 42 as an integral part. Exhaust passage 41 is partially closed off at the bottom by partition 43. Figure 8 shows a cross-section along line 88 of Figure 7. Opening 43a lies within the plane of partition 43 and opens the hose 41 to the outside. Partition 44 is mounted in the interior of mask 38 transverse to the longitudinal axis of tubes 41 and 42, and contains aperture 45. Fresh air enters in the direction of arrow 46, and then passes to the outside in the direction of arrow 47 through opening 43a. Upon inhaling, the fresh air is aspirated through opening 45. If the supply of air through hose 46 is small, air from the outside flows through aperture 43a and tube 41 back into the mask in order to meet the additional air requirements under maximum breathing conditions. During the exhaling phase, the fresh air flowing through hose 42 flushes out antechamber 41. The exhaled air passes to the outside through exhaust valve 39. The larger the antechamber formed by tube 41 and space 48, the smaller the fresh air requirement of the respirator. Of course, the supply of fresh air must be such that the total amount is sufiicient for breathing.
Instead of tube 41, a tubular sheet metal jacket, an oval cannister, orany hollow container may be substituted. The distance between openings 45 and 43a should be as large as possible. The hose 42 does not have to extend all the way up to the mask.
Having now described the means by which the objects of the invention are obtained; we claim:
1. A respirator for handling excess quantities of air comprising a face mask, a fresh air supply intake tube joined to said mask, and a housing forming a second tube at least partiallysurrounding said intake tube and communicating both with the interior of the mask and the outside air and forming an antechamber between the interior of said mask and said intake tube.
2. A respirator as in claim 1, further comprising an opening between the antechamber and the interior of said mask and spaced as far as possible from said second tube.
3. A respirator as in claim 2, further comprising a partitionin said mask containing said opening.
References Cited in the file of this patent UNITED STATES PATENTS 404,986 Rudolfy June 11, 1889 680,419 Sehaelfer Aug. 13, 1901 1,615,718 Olgard 'Jan. 25, 1927 1,824,512 Szamier Sept. 22, 1931 1,926,027 Biggs Sept. 12, 1933 FOREIGN PATENTS 137,217 Great Britain Jan. 8, 1920 284,946 Switzerland Jan. 5, 1953