US3129707A - Breathing apparatus - Google Patents

Description

April 21, 1964 M. BECKER ETAL 3,129,707

BREATHING APPARATUS Filed Nov. 12, 1954 4 Sheets-Sheet 1 INVENTORS EARL M. BECKER BY JOHN ,1. BRIDGE ATTORNEY A ril 21, 1964 E. M. BECKER ETAL BREATHING APPARATUS Filed Nov. 12, 1954 4 Sheets-Sheet 2 INVENTOR. EARL M. BECKER I By /JO;N J. BRIDGE j ATTORNEY April 21, 1964 E. M. B EKER ETAL 3,129,707

BREATHING APPARATUS 4 Sheets-Sheet 3 Filed Nov. 12, 1954 IN VEN TORS EARL M. BECKER JOHN J. BRIDGE ATTORNEY A ril 21, 1964 E. M. BECKER ETAL 7 7 BREATHING APPARATUS Filed NOV. 12, 1954 4 Sheets-Sheet 4 IN VEN TORS EARL M. BECKER JOHN J. BRIDGE ATTORNEY United States Patent 3,129,707 BREATHENG APPARATUS Earl M. Becker, Pittsburgh, and John 5. Bridge, Turtle Creek, Pa., assignors to Mine Safety Appliances Company, Pittsburgh, Pin, a corporation of Pennsylvania Fiied Nov. 12, 1954, Ser. No. 468,432 1 (Hahn. (Ci. 128-142) This invention relates to improvements in self-contained breathing apparatus, and more particularly in breathing apparatus adapted for use in underwater swimmlng, diving and salvage work. Although the invention will be particularly described in connection with breathing apparatus for use under water, it is to be understood that the apparatus may readily be adapted for use in any atmosphere which is inadequate for normal breathing.

Existing self-contained breathing apparatus, especially those designed for underwater use, have had high resistance to breathing by the wearer. The principal disadvantage of high breathing resistance is that it requires the expenditure of additional energy by the wearer of the apparatus so that he rapidly becomes fatigued or may even reach the point where the loses control of his senses. Present day breathing bags, for example, are not constructed to efliciently simulate or follow the movements of the wearers lungs during all swimming positions. That is, insuflicient flexibility is present in these bags whereby the bags will expand and contract, as do human lungs, during the inhalation and exhalation cycles, regardless of the position of the swimmers body. This inflexibility raises the breathing resistance in the apparatus to the point Where it is extremely difficult to either inhale or exhale without exerting a great deal of physical effort throughout the entire breathing cycle.

Another disadvantage found in self-contained breathing apparatus used underwater is that the various valves included in the apparatus and necessary to the breathing system are impractical due to their complexity in construction and operation. Thus, the wearer is under constant strain and danger having knowledge that his apparatus may not always function safely and may not be susceptible to quick manipulation when an emergency arises.

Regarding the regulating valve for the compressed oxygen cylinder containing oxygen for breathing purposes, the existing practice includes the turning of a hand wheel on the valve for obtainin emergency oxygen flow, and determining the amount of oxygen in the cylinder at any given moment by visually inspecting a pressure gauge. This type of construction has two distinct disadvantages. The first being that, when an emergency arises, the wearer may not have sutiicient time or be physically able to turn the hand wheel the necessary turns in order to obtain the required emergency flow of oxygen. Secondly, visual gauges are, one, temperamental and thereby may give erroneous readings, and two, these gauges are readily susceptible to breakage. Furthermore, the condition of the water may be such that the gauge cannot be seen or the operation performed by the user may be such that he is not in a position to see the gauge. Consequently, emergency oxygen may not be available when needed and the oxygen pressure in the tank may decrease to the point where the wearer of the apparatus no longer has an opportunity to safely surface or reach his home base prior to the depletion of oxygen.

Considering the face mask valves, no positive acting, simple and readily manipulative means has been employed in the prior art teachings, whereby communication between the face mask and other breathing system components can be opened and closed, whereby fluid can be ejected from the face piece, and whereby fresh air can be admitted to the face mask. As the safety of 3,129,707 Patented Apr. 21, 1964 ice the wearer is always dependent upon the proper functioning of such valves, and as split second operation of the valves may be necessary in emergencies, it is obviously of utmost importance that the valves be constructed in a manner to accomplish these desired results.

Accordingly, it is among the objects of this invention to overcome the above-mentioned disadvantages and generally improve self-contained breathing apparatus.

It is an object of this invention to provide a self-contained breathing apparatus so constructed that the wearer can breathe with ease by keeping the resistance to breathing in the apparatus to a minimum.

Another object is to improve the construction of the breathing bag to increase its flexibility and provide a large exchange volume to permit the bag to follow the movement of the wearers lungs and decrease breathing resistance.

Another object is to provide an apparatus whose buoyancy can be controlled by overcoming the natural buoyancy of the wearer and apparatus to permit the wearer to quickly ascend without having to exert physical effort. Provision is also made to permit the wearer to use the apparatus as an escape device.

Another object of this invention is to improve the various valves in the breathing system by simplifying the valves in construction and providing means whereby the valve may be readily operated in a positive fashion.

A further object of this invention is to provide an improved regulating valve for the compressed oxygen tank of the self-contained breathing apparatus so that emergency oxygen flow may be quickly and easily obtained and provide a feeler gauge responsive to the oxygen pressure in the compressed oxygen tank.

A still further object of this invention is the provision of a breathing mask comprising means which permits the breathing of atmospheric air through the mask when the wearer is not under water, thereby preventing the necessity, at such times, of removing the mask, and permits the wearer to conserve the supply of oxygen.

Since under some conditions, the wearer of the apparatus might come to the surface at a point remote from his original base of operations, it is an object to provide means which enable him to remove his face mask in the water without permitting water to enter the breathing bag or other components of the breathing system.

Other objects and advantages will become apparent from the following detailed description and annexed drawings in which:

FIG. 1 shows a front elevation of the apparatus of this invention as supported in place on the body of a wearer;

FIG. 2 shows the apparatus in side elevation;

FIG. 3 is a rear elevation of the apparatus with parts broken away;

FIG. 4 is a perspective view of the breathing bag;

FIG. 5 is an enlarged vertical sectional view of the face mask, with a part broken away, taken on line VV of FIG. 1;

FIG. 6 is an enlarged fragmentary vertical sectional view of the shut-off valve showing the components in a closed position;

FIG. 7 is a vertical sectional view of the fresh air valve taken on line VIIVII of FIG. 5;

FIG. 8 is an enlarged exploded perspective view of part of the fresh air valve; and

FIG. 9 is a fragmentary vertical sectional view of the fresh air valve illustrated in FIG. 7 but shown in the open position.

Referring now to the drawings, the apparatus comprises a comfortable, tight fitting, flexible rubber molded face mask 1 securely held in place on the wearers face by adjustable flexible rubber head straps 2. A flat, oval, glass lens 3 extending laterally of the face mask is mounted on the upper portion thereof across both eyes of the wearer. A shut-oif valve 4 is securely mounted to the lowermost portion of the face mask well below lens 3 and includes a dump valve, all to be more particularly explained hereinafter. A conventional inhalation check valve housing 6 is mounted on one side of valve 4 and an exhalation check valve housing 8 is mounted on the other side, each being connected to a breathing bag 10 by flexible inhalation and exhalation hoses 12 and 14, respectively, by female fittings 15 and 16 threadedly connected to male fittings 17 and 18 attached to breathing bag 19. The components interposed between the mask and breathing bag are arranged for connection in fluid tight relationship.

Oxygen for breathing is supplied to bag 10 by cylinder 20 through regulating valve 22, connecting hose 24 and fitting 26 which includes a one-way valve similar to the type used in vehicular inner tubes. Fitting 26 is connected to bag 10 in any convenient manner and is in open communication with the bag (FIG. 3). A pair of female fittings 27 and 28 are mounted on the rearwardly and downwardly extending portion of bag It for threaded connection to complementary male fittings 29 and 30 extending from an air-purifying canister 31.

Canister 31 is of the carbon dioxide absorbent type and is rectangular in shape for containing a well-known chemical for absorbing the carbon dioxide from the exhaled breath. The canister is so constructed that it has a large cross-sectional area in proportion to its length, thus reducing resistance to gas flow. One type of efiicient carbon dioxide absorbing chemical that may be used is a combination of lime, sodium hydroxide and water.

Attention is now directed to the vest and harness that connect and carry the various parts of the apparatus in place on the body of the wearer. Vest 33 is made of lightweight, but sturdy, cloth material having portions extending over the shoulders, across the front, back, and around the sides of the wearers body. The cloth is continous across the front and rearwardly over the shoulders but is separated vertically along the back and sides. The sides are each connected together by snap fasteners 34 and the back separation is laced together by lace 35. Once the lace 35 has been adjusted to a particular body size, vest 33 is donned by merely slipping the vest over the head of the wearer and snapping together fasteners 34. Straps 36 are sewed directly to vest 33 and are constructed to have portions extending downwardly on the front side of the vest. Other portions 37 of straps 36 are arranged to extend circumferentially of cylinder 20 for strapping the cylinder to the vest.

Noting FIG. 3, each strap 38 is sewed to the vest on each side of lace 35 and is so constructed as to extend around canister 31 for mounting the canister in its opera tive position. Buckles 39 are adjusted to tightly strap the canister to the vest. Referring to FIG. 1, straps 36 carry quick-disconnect grippers 40 for connection to the front end of each crotch strap 41. The other ends of crotch straps 41 (FIG. 3) include safety fasteners 42 adapted for connection to D-rings 43 mounted on straps 38. As is readily noted, grippers 40 allow adjustment of the crotch straps 41 and also permit the crotch straps to be rapidly disconnected from the front side of vest 33 for quickly releasing the straps from the wearers legs. Strap portions 37 also include safety fasteners 44 for connection to D-rings 45 secured to breathing bag 10. All of the abovementioned straps are constructed of high tensile strength webbing highly resistant to water damage.

Particular reference is now made to the breathing bag 10 shown in FIGS. 14 wherein it can be noted that the bag is constructed of a lightweight, durable rubberized fabric or similar material. Bag 10 is shaped similar to an inverted V and the general contour of the bag is such that it may be comfortably draped over the upper portion of the wearers body, regardless of body size. Bag 10 contains an opening 46 at the top thereof large enough to accommodate the wearers head when the breathing bag is being donned. The inner section 47 of bag 10 fits against the body and is smooth to enhance the wearing comfort, and the outer section 48 of bag 10 is pleated or folded to form rounded corrugations 48a extending radially =from opening 46. A flexible exhalation hose 49 (FIG. 3) is contained within bag 10 for connection between male fitting 18 and female fitting 27 to provide a closed fluid passage between exhalation hose 14 and canister 31. The shape of bag 10 permits good positioning of the bag on the body of the user and allows free movement during all types of operations. The corrugations 43a on the outer section 43 of the bag greatly improve the flexibility of this element to allow the bag to flex with the movement of the users lungs and provide a large breathing exchange volume. Accordingly, since the bag will flex with small diiferential pressure changes, low breathing resistance is always available to the user while swimming in any position. The shape of the breathing bag and the manner in which it is positioned on the wearer as described permits the wearer to inhale and exhale without undue exertion. Also, positioning of the bag in the manner described provides good flotation when the bag is so used. That is, the head of the wearer will always ride well above the surface of the water and the wearer can float comfortably until he leaves the water.

In order to prevent rupture or failure of the breathing bag 10 or any part of the respiratory system when valve 4 is closed, or when the bag is inflated for emergency flotation, a pressure relief valve 5% of conventional design is connected to the back of the bag on outer section 48 (FIGS. 2 and 3) and is set to open at any desired predetermined pressure.

Reference is now made to the shutoif valve 4- mounted on the lower part of the face mask 1, and in this respect, attention is directed to FIGS. 1, 2, 5 and 6. Valve 4 comprises a main housing 52 secured to the face mask by a clamp 53. The upper part of housing 52 comprises a dished-out or cup-shaped top portion 54 and cylindrical bottom portion 54a forming an upper chamber 55. Cylindrical portion 54a forms a valve seat 56 and is connected to a dump valve housing 58 in a manner to communicate with cup-shaped portion 54. The lower part of housing 52 comprises a lower chamber 57 with which inhalation passage 60 of check valve housing 6 communicates. An exhalation passage formed by check valve housing 8 (not shown) similarly communicates with chamber 57 on the side of housing 52 opposite to passage 60. A valve head 61 is contained within housing 52 by a valve stem 62 extending into the housing 52 through a closure cap 63 threadedly connected to the housing. Head 61 is connected to the threaded inner end of stem 62 by a threaded nut 64 and may be shimmed for slightly adjusting the valve upwardly or downwardly, as the case may be. The outer end of stem 62 comprises a hemisphere 65 having a small dished-out portion 66. Spring 67 is interposed between hemisphere 65 and cap 63 and its normal extension maintains valve head 61 unseated from seat 56 and, consequently, in the open position. When hemisphere 65 is depressed to compress spring 67 (FIG. 6), valve head 61 is seated on seat 56 to close the communication between inhalation passage 61! and the exhalation passage (not shown) on one hand and the face mask 1 on the other hand. In order to provide a locking means for maintaining valve head 61 against seat 56, and providing a quick release mechanism for disengaging these valve elements, a small ball 68 is rotatably suspended from a wire holder 69 pivotally secured to cap 63. When only a momentary closure of valve head 61 is desired, hemisphere 65 is finger-depressed. If permanent closure is required, ball 68 is frictionally locked within dished-out portion 66 by downward pivotal movement of holder 69 and rotative and slideable movement of ball 68 against the curved surface of hemisphere 65 depressing the latter element. From the above description, it is readily seen that the valve construction permits a means for quickly locking or unlocking valve head 61 by merely pivoting ball,

68 into portion 66 or snapping ball 68 out of portion 66.

The dump valve included in valve 4 comprises the housing 58 containing a ball check valve 70 spring loaded or biased to the closed position against a seat 70a by a spring 71. The outlet end of housing 58 is threaded to receive a knurled safety closure 73 and includes seat 72 against which the solid lower portion of closure 73 is seated for closing the outlet. Passage 74, formed by the upper and lower portions of closure 73, permits open communication between the interior of housing 58 and the surrounding atmosphere when closure member 73 is unscrewed to the open position, that is, when the lower portion of the closure is unscrewed from seat 72. Since ball 70 is spring loaded to the closed position, communication between the face mask and the outside is only possible when pressure, by blowing or the like, is applied inside of the face mask.

When the need arises to eject or empty fluid from the face mask, hemisphere 65 is depressed to close valve head 61 and closure 73 is unscrewed to open the outlet end of housing 58. It is then only necessary to blow against ball 70 against the action of spring 71 to eject fluid from the dump valve. As is seen in FIG. 5, the cup shaped portion 54 and housing 58 are so positioned at the bottom of the face mask as to provide an efficient trough or drain for any fluid collecting in the mask.

Particular reference is made to FIGS. 5, 7, 8 and 9 wherein fresh air valve is mounted on the side of face mask 1 and comprises an internally threaded tubular housing 77 clamped to the face mask by a cylindrical locking member 78 threadedly connected to the housing against lock washer 78a. Openings 79 on the outer end of housing 77 cooperate with the passage 77a formed by the housing to provide fluid communication between the outside air and the interior of the face mask. A valve head 80 having an integral stem portion 81 is spring loaded to the closed position by spring 82 against rubber O-ring seat 83. Head 80 is centered and spaced from the inner wall of housing 77 by spider legs, one of which is shown at 80a, FIGS. 7 and 9. Stem 81 extends through a centrally disposed aperture 81a of housing 77 into a cylindrical housing extension element 84. Element 84 is circumferentially cut out along its bottom portion forming a U-shaped aperture 86 having lateral aperture extensions 87 and a U-shaped lug 87a. The upper part of element 84 is cut out to form an inverted U-shaped aperture 88. A rectangular lever 85 comprises an aperture 89 and a cam 90. When assembling lever 85 with element 84, note FIGS. 7 and 8, stem 81 is depressed against spring 82 permitting the upper portion of lever 85 to be pushed upwardly until a portion of cam 90 passes into aperture 88 and lug 87a is aligned with and passes into aperture 89. Thus, when the lever is so located, stem 81 and valve head 89 return to the original closed position permitting lever 85 to hang rather loosely as shown in FIG. 7. The distance between the end of stem 81 and lug 87a is smaller than the thickness of lever 85 to prevent accidental dislodgment of lever 85 from element 84 when valve head 80 is closed. Looking at FIG. 7, as lever 85 is rotated toward the left, cam 90 engages stem 81 to depress valve head 80 against spring 82 for unseating the valve head from O-ring seat 83. Further rotation of lever 85 to the ultimate position as shown in FIG. 9 fully opens valve 5 and locks it in place by the interposition of cam 90 between stem 81 and lug 87a. Although the valve is maintained in the open position as described, a mere flick downwardly of lever 85 will immediately seat valve head 80 thus closing fluid communication between the surrounding medium and interior of the face mask.

When the user of the apparatus is in the position to breathe fresh air and does not desire to remove the face mask, shut-off valve 4 is closed and fresh air valve 5 is opened. Beside the readily manipulative features of fresh air valve 5, the importance of the valve in a selfcontained breathing apparatus when constructed accord ing to this invention should be quite apparent. It is possible for the user to breathe atmospheric air without the removal of the face mask and thus prevent being subjected to the full force of the water and other dangerous elements when the wearer has surfaced. What little water may enter fresh air valve 5, due to the roughness of the water on the surface, may be ejected through the dump valve. Also, the user of the apparatus may breathe atmospheric air while moving about at his base of operations after the mask has been donned and properly adjusted to thus conserve the supply of oxygen in the oxygen cylinder.

Also, the closing of shut-off valve 4 permits the conservation of the oxygen supply when the user does not desire oxygen for breathing purposes. Furthermore, when it is desired that the breathing bag 10 be used purely as a flotation bag, all communication between the face mask and the bag may be cut off for this purpose. When valve 4 is closed for operating the bag during flotation, sufiicient oxygen may be supplied to the bag to provide the necessary buoyancy for the wearer.

Looking at FIGS. 1, 2 and 3, the regulating valve 22 for the oxygen supply system is interposed between bag 10 and cylinder 20 and has two primary functions, firstly, to regulate the flow of oxygen from the cylinder to the bag and provide emergency oxygen supply to the bag, and secondly, provide a means for determining the amount of oxygen in the cylinder by the sense of feel. Valve 22 comprises a housing 91 having an on-ofi hand wheel 92 which opens and closes the passage of oxygen coming from cylinder 20. A knurled hand knob 93 is mounted on valve housing 91 and is so constructed as to permit regulation of the oxygen flow from cylinder 20 to bag 10. Knob 93 includes a hand lever 94 which when depressed overrides the normal setting for the oxygen flow and delivers an emergency flow of oxygen to the bag. For example, knob 93 may contain several settings, such as for supplying a half, one, or two liters of oxygen per minute to the breathing bag and a shut-off setting, and when lever 94 is squeezed or depressed, on the order of 15) liters per minute of oxygen can be supplied to bag 10. A feeler rod 95 extends through housing 91 and is responsive to the pressuure of oxygen in cylinder 20. The amount of rod extension beyond housing 91 is dependent upon the pressure available in cylinder 20. In its normal operation, rod 95 would be preset so that when the rod no longer extends through the housing, only emergency oxygen pressure would be available in cylinder 29. Accordingly, it is seen that it is merely necessary to place the hand over the rod to determine whether normal oxygen pressure is available or whether only an emergency pressure exists. Of course, the emergency pressure'would be of a value which would permit the user of the apparatus to reach a breathable atmosphere before the oxygen supply became exhausted. An oxygen outlet fitting 96 extends outwardly and below knob 93 and includes a one-way valve similar to an inner tube valve to permit oxygen to flow into hose 24 when hose fitting 97 is threadedly engaged to fitting 96 but prevents escape of oxygen when fitting 97 is disconnected. The other end of hose 24 is secured to a hose fitting 98 similar to the one shown at 97 and cooperates with one-way valve type fitting 26 in a manner identical to that just described for fittings 96 and 97. The shut-off setting is included in knob 93 to provide a rapid means for stopping the flow of oxygen into bag 10 independently of hand wheel 92 since the latter normally requires several turns before oxygen can be stopped. A detailed description of the construction of valve 22 is not necessary to this invention since the instant improvement relates to the combination of valve 22 broadly with other elements of the self-contained breathing apparatus herein described. The specific details of this valve, however, are found in our co-pending application for a patent, Serial No. 488,818 filed February 17, 1955 and entitled Gas Dispensing Apparatus, now Patent No. 2,895,640 and is by reference incorporated herein. As is well known in the art, oxygen is supplied to the face mask only in amounts required by the user. That is, the frequency of inhalation and depth of inhalation determines the amount of oxygen supplied since the inhalation check valve housing 6 closes on the exhalation of the user.

The operation of the complete underwater self-contained breathing apparatus will now be described. Assuming that the apparatus is completely disassembled, the wearer will first don vest 33 by placing the same over his head and then closing snap fasteners 34 under his armpits. If adjustment of the vest is required, lacing 35 will be loosened or tightened before or after the vest is donned. Crotch straps 41 are attached to D-rings 43 by fasteners 42 rearwardly of the vest and to grippers 40 on the front side of the vest. After the vest is in place, canister 31 is strapped to the vest by straps 38 and tightened in place by buckles 39. Next, cylinder 20 including valve 22 is attached to the vest by portions 37 of straps 36. Breathing bag 10 is placed over the head of the wearer through opening 46 disposing the bag on the shoulders, chest and back. The breathing bag is then attached to the donned apparatus in the front by securing fasteners 44 to D-rings 45 and in the rear, by threadedly connecting female fittings 27, 28 to male fittings 29, 30 of canister 31. Face mask 1 and valve 22 can then be connected to the breathing bag by attaching hoses 12 and 14 and threadedly securing hose 24 to fittings 26 and 96. The fresh air valve being in the open position, and shut-off valve 4 being closed, mask 1 may be adjusted on the head by straps 2. When the diver is ready to submerge, hand wheel 92 is turned to open valve 22 and knob 93 is adjusted to supply oxygen to bag 10. Valve 4 is opened, fresh air valve 5 is closed and oxygen is supplied to face mask 1 for starting the respiratory cycle. As the diver breathes, check valve housing 6 opens on the inhalation cycle while check valve housing 8 remains closed. Conversely, on the exhalation cycle, check valve housing 6 closes and check valve housing 8 opens to permit the exhaled air to pass through hose 14, hose 49, and canister 31 where the carbon dioxide is absorbed and the breathing air is purified for entrance to breathing bag 10 for subsequent recirculation into the face mask through hose 12. Pure oxygen from cylinder 20 passes through valve 22 and hose 24 into breathing bag 10 adjacent hose 12.

Regardless of the swimming position, the breathing apparatus operates with a low breathing resistance factor. When emergency oxygen flow is desired, lever 94 is depressed overriding the normal setting of knob 93. This increased flow of oxygen may be required when the wearer is doing exhaustive work or he finds that the additional oxygen is a necessity. As the diver surfaces, he closes valve 4 and upon reaching the surface, opens fresh air valve 5 for breathing atmospheric air. When immediate or emergency buoyancy is required, valve 4 may be closed and emergency lever 94 may be depressed to fill bag 10 giving the diver an opportunity to quickly surface. The oxygen filled bag will provide a flotation means keeping the divers head above water. Also, in the case of emergency escape, for example, from a submerged vessel, the oxygen cylinder 20 may be dispensed with by supplying compressed air or oxygen into bag 10 from a source within the vessel. After the source of oxygen supply has been removed, the wearer may by any well-known method ascend from the submerged vessel to the surface of the Water. By manipulating valve 4, suflicient oxygen can be supplied to the face mask for breathing purposes as the user ascends to the surface.

If at any time, whether on or under the water, fluid need be ejected from the mask, it is necessary only to unscrew closure 73 and blow against valve 70.

After the apparatus has been used for some time, it may be necessary to remove canister 31 and replace it with a fresh one. Also, cylinder 20 must be replaced as the oxygen is used up, but both components are usually designed to sustain breathing for a reasonably long period of time.

Having explained the principle of the present invention and having illustrated and described what is considered to be the best embodiment, it is to be understood that, within the scope of the appended claim, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

Breathing apparatus comprising a face mask, a houslng secured to and in fluid communication with said mask, inhalation and exhalation fluid passage means connected to said housing, valve means interposed between said passage means and mask for opening and closing fluid communication between said passage means and mask, said valve means comprising a valve head biased to the open position and means having a curved surface for actuating said valve head, and pivoted locking means operable against said curved surface for releasably looking said valve means in the closed position.

References Cited in the file of this patent UNITED STATES PATENTS 7,476 Lane July 2, 1850 575,840 Kenly Jan. 26, 1897 1,088,817 Graham Mar. 3, 1914 1,330,798 Gilles Feb. 17, 1920 2,348,074 Lambertsen May 2, 1944 2,362,240 Bonilla Nov. 7, 1944 2,362,643 Lambertsen Nov. 14, 1944 2,402,984 Browne July 2, 1946 2,403,991 Murphy July 16, 1946 2,444,029 Bowen June 29, 1948 2,456,130 Lambertsen Dec. 14, 1948 2,758,596 Cupp Aug. 14, 1956 2,792,828 Engelder May 21, 1957 2,814,291 Holmes Nov. 26, 1957 FOREIGN PATENTS 13,604 Great Britain 1905 542,955 Great Britain Feb. 4, 1942

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