US2710978A - Apparatus for inflating life rafts - Google Patents

Description

June 21, 1955 s. w. ALDERFER APPARATUS FOR INFLATING LIFE RAFTS 2 Sheets-Sheet 1 Filed June 28, 1952 m m m m 'STERLING W.

ALDERFER ATTORNEYS June 1955 s. w. ALDERFER APPARATUS FOR INFLATING LIFE RAFTS 2 Sheets-Sheet 2 Filed June 28, 1952 United dtates Patent APPARATUS FOR INFLATING LIFE RAFTS Sterling W. Aiderfer, Akron, Ohio, assignor, by mesne assignments to Knapp-Monarch Company, St. Louis, Mo., a corporation of Delaware Application June 28, 1952, Serial No. 296,186

4 Claims. (Cl. 9-11) The invention relates generally to inflatable pneumatic life rafts such as are carried by aircraft for use when forced down at sea, and more particularly to a novel method and apparatus for inflating the raft by using the usual steel bottle of carbon dioxide gas.

Conventional pneumatic life rafts may be substantially i.

elliptical in outer configuration, and the outer peripheral portion consists of a tubular chamber having flexible bulkheads or partitions dividing the chamber into two or more compartments. The inflation system usually consists of a steel cylinder or bottle containing liquefied carbon dioxide under high pressure and having a valve and discharge connection adapted for attachment to a manifold which distributes the gas to each compartment, carbon dioxide being used because of its extremely rapid rate of expansion. The manifold is T-shaped, having a floating spring in the cross bar of the T urging two discharge check valves at its outer ends inwardly against their seats, and the discharge valves communicate one with each compartment.

In order to prevent premature expansion of the gas in the manifold with rapid absorption of heat, all the orifices in the manifold are kept small, but when the gas passes through the discharge check valves into the compartments with a drop in pressure to atmospheric or a maximum of about 2 pounds per square inch, it expands so rapidly that it is impossible to prevent the formation of snow or ice at the valve orifices. This condition is greatly aggravated at subnormal tempera tures, and increasingly so at temperatures ranging downward from 60 F. The discharge of gas containing particles of snow and ice through the small valve orifices thus tends to close those orifices. Because the valve orifices are small and because the floating spring merely tends to hold the valves in position with no equalizing effect under abnormal condition such as lowered temperatures or a badly folded or cramped position of the raft, one of the valve orifices is apt to become clogged more than the other. This causes unequal distribution of gas to the two compartments, and results in overinflation and sometimes bursting of one side of the raft while the other side is still collapsed or underinflated. Under extreme conditions both valve orifices may become plugged, momentarily preventing further inflation in either side.

When one considers that the lives of several persons may be entriely dependent upon the proper and almost instant inflation of one of these rafts in an emergency and especially in frigid temperatures where the effects of exposure in the water are more critical, the importance of proper and equal distribution of carbon dioxide to the compartments under any and all conditions cannot be over-emphasized.

The primary object of the present invention is to provide an improved inflation system which will overcome the foregoing disadvantages and insure proper and equal distribution of gas throughout the compartments of a pneumatic life raft under any and all adverse con-' ditions.

Another object is to provide raft inflating mechanism which can be applied to conventional pneumatic life rafts without requiring substantial change in the construction of the rafts.

A further object is to provide novel carbon dioxide distributing mechanism for pneumatic life rafts which is simple and inexpensive to manufacture and practically foolproof in operation.

These and other objects are attained by the method, parts, combinations and arrangements comprising the present invention, a preferred embodiment of apparatus for carrying out the invention being shown in the accompanying drawings and described in the specification. Various modifications may be made within the scope of the invention as defined in the appended claims.

Referring to the drawings:

Fig. 1 is a schematic plan view of a pneumatic life raft embodying the apparatus of the present invention;

Fig. 2 is an enlarged fragmentary cross sectional view as on line 2-2, Fig. 1;

Fig. 3 is a fragmentary elevation on line 33, Fig. 2; and

Fig. 4 is a fragmentary sectional view on line 44, Fig. 2.

The pneumatic raft shown in Fig. 1 consists of an inflatable flotation tube 10 generally elliptical in shape forming the outer periphery of the raft, and supporting a flat bottom wall 11 secured to the bottom of the tube. Midway of one side of the tube 10 is a usual flexible partition or bulkhead 12, and in one form of conventional raft there are two of these dividing the tube into two equal compartments or gas chambers. An inflatable hollow seat 13 extends transversely between the sides of the tube at its central portion. The tube 10, bottom 11, bulkhead 12 and seat 13 may all be constructed of rubberized fabric in a usual and well known manner, and the tube compartments and seat are provided with the usual mattress valves (not shown), for deflating or attaching a hand pump. Many other accessories, such as oar locks, ropes, etc., are attached to the boat but have no pertinence to the present invention, and have been omitted for the sake of clarity.

In the conventional raft, the T-shaped distributing manifold previously described is connected between the carbon dioxide bottle and the flotation tube at one of the bulkheads 12 so that one distributing check valve communicates with each compartment of the tube. in the preesnt invention a double bulkhead arrangement having spaced bulkheads 14 is substituted for one usual bulkhead i2, and the bottle is connected to the chamber or space between bulkheads 14-. Other than the specific construction of the double bulkheads and the gas connection therebetween, no further structural change in the life raft from conventional construction is necessary.

The bulkheads 14 are constructed of the same rubberized fabric as bulkhead 12 and are attached to the inner surface of the tube 10 in the same manner by means of the usual reinforcing tape 15 adhered to the rim flange of the bulkhead material and the adjacent tube surface, with angular shoes 16 of bulkhead material adhered to and backing up the bulkhead on the side opposite the rim flange. The bulkheads 14 are spaced apart sufiiciently to form a relatively small preliminary expan sion chamber P which is large enough to hold all the snow which may be formed by the expanding gas.

Substantially midway of the bulkheads 14 on the outside of the tube it is an air inlet valve 17 of usual con struction fitted with an inlet nipple having a quick coupling nut for attachment to the valve discharge head 18 of the steel bottle or cylinder 19 containing the carbon dioxide gas under pressure. Thus, the carbon dioxide entering the chamber P vaporizes at a reasonably low pressure of say pounds per square inch, forming a certain amount of snow which collects in the chamber and quickly evaporates.

In the central portion of each bulkhead 14 is a low pressure diaphragm check valve of novel construction indicated generally at 20, for exhausting the gas into compartments of the tube 10. These valves may be constructed to open at pressures as low as .l" of mercury. Referring to Figs. 2, 3 and 4, the valves 29 each include an internal metal disk 21 having a relatively large outlet orifice 22 which may be of the order of /s to elfectively prevent any clogging of the orifice by snow or ice even at low temperatures. The disk 21 is enclosed in a doublewalled disk preferably of soft natural or synthetic rubber which has orifices 23 and 24 in its inner and outer walls 25 and 26 respectively, said orifices registering with the orifice 22 in disk 21. Radially outward of the disk 21 the walls 25 and 26 preferably join and form a circumferential tapered rim or fin 27 which may be enclosed between and adhered to the fabric of the bulkhead 14 and a circular strip of reinforcing tape 23 to make a tight continuous joint all around the opening 25 in the bulkhead within which the valve 20 is mounted.

A diaphragm 30 which may be of rubber or neoprene is attached to the outer side of each valve 20 preferably at equally spaced points on its periphery. As shown in Fig. 3 the diaphragm 30 may be substantially square with tubular portions 31 at its corners, in which are located the tubular heads of rivets 32 having their opposite ends flanged under the metal disk 21. The head of rivets 32 are received in metal lugs 33 which are embedded in the tubular portions 31 of the diaphragm and the outer Wall 26 of the rubber disk. These lugs 33 enable the tubular heads of the rivets 32 to be upset as indicated at 3-4 to secure the diaphragm 30 to the rubber wall 24 and the metal disk 22.

The outer wall 26 of the rubber disk is provided with concentric sharp- edged ribs 35 and 36 which normally contact the inner surface of the diaphragm 3 3. but a very slight pressure, which may be as low .3 inch of mercury, on the central portion of the diaphragm under the outlet orifices 22 and 24 will break the contact and allow gas to escape from under the diaphragm between the corners thereof. Accordingly, when the chamber P is filled with gas, it will pass through the outlet orifices and out from under the diaphragm without any tendency to clog the check valves 20, because the outlet orifices 22 and 24 are relatively large and the pressure of the gas passing therethrough is quite low due to the fact that the pressure has been reduced in chamber P and the re sulting snow collected therein.

The distribution of gas through the valves 28 to the two compartments in the tube 10 is substantially uniform because of the prevention of clogging the outlet orifices. Moreover, should one compartment become inflated faster than the other for any reason, the increased back pressure in the one compartment would at the low exhausting pressures, automatically operate to equalize the pressures in the two compartments by allowing the di aphragm exhausting into the other compartment to open farther against the lower back pressure. In the conventional inflating device using the T-shaped manifold previously described, the expansion of gas is governed by the high pressure within the steel cylinder and the relatively low back pressures in the compartments of the order of not more than 2 pounds per square inch, have no material effect in respect to equalizing pressures in the two compartments.

It will be apparent that instead of forming the preliminary expansion chamber P in one side of the tube 10 as shown in Fig. l, the chamber can be formed within the hollow seat 13, and the gas exhausted into the tube 10 on each side of opposite bulkheads 12 by diaphragm valves 20' in the end walls of the hollow seat; In such case the valve discharge headi18 of the steel cylinder 19 would be attached to an intermediate portion of the tubular seat.

In the operation of inflating a life raft according to the present invention, the steel cylinder 19 containing liquid carbon dioxide is quickly connected to the inlet valve 17 and the discharge head 18 opened in the usual manner. Carbon dioxide partly in vapor and partly in liquid form enters the chamber P and immediately drops in pressure causing the liquid to vaporize and expand and producing particles of snow and ice within the chamber. The expanding gas opens the diaphragm 30 and ex hausts at low pressure through the valves 20, the increas' ing back pressures in the compartments acting to equalize the pressures in the respective compartments. Thus, in a matter of a few seconds, both sides of the tube 10 are equally inflated, even at sub-normal temperatures, whereupon the steel cylinder can be disconnected if desired.

The novel inflating system of the present invention overcomes all the difiiculties of improper and unequal inflation incurred with prior inflating devices, and adequately protects the lives of persons dependent upon rapid and foolproof operation of life raft inflating devices under all kinds of weather conditions. The invention is easily applied to conventional rafts without substantial change in construction and is inexpensive to manufacture.

While a preferred apparatus for carrying out the invention is shown and described herein, it is understood that rarious changes and modifications in details of construction may be made without departing from the scope of the claims.

What is claimed is:

l. in a pneumatic life raft having a flotation tube and :1 vertical bulkhead in one side of its flotation tube, a pair of spaced apart bulkheads in the opposite side of said tube forming a preliminary expansion chamber therebetween, means for admitting liquefied carbon dioxide gas under pressure into said chamber, a diaphragm check valve in ':.;ch of the chamber bulkheads for exhausting said gas at low pressure into opposite ends of the tube, said check valves including a resilient wall having a central outlet orifice of the order of about as inch in diameter surrounded by concentric external ribs, and a resilient diaphragm normally abutting the outer edges of said ribs to close the valve but disengageable therefrom by low pressures within the chamber of the order of about .1 inch of mercury.

2. In a pneumatic lift raft having a flotation tube and a vertical bulkhead in one side of its flotation tube, a pair of spaced apart fabric bulkheads in the opposite side of said tube forming a preliminary expansion chamber therebetween, means for admitting liquefied carbon dioxide gas under pressure into said chamber, a diaphragm check valve in each of the chamber bulkheads for exhausting said gas at low pressure into opposite ends of the tube, said check valves including a metal disk embedded in a resilient wall secured to the fabric bulkhead, said disk and resilient wall having a central outlet orifice of the order of about A; inch in diameter surrounded by concentric external ribs on the resilient wall, a resilient diaphragm normally abutting the outer edges of said ribs to close the valve but disengageable therefrom by low pressures within the chamber of the order of about .1 inch of mercury, and means securing the diaphragm at spaced points on its periphery to the outer part of the resilient wall.

3. In a pneumatic life raft having a flotation member compartmented to define at least a pair of gas-receiving compartments, means on said life raft defining a preliminary expansion chamber adapted to communicate with said gas-receiving compartments, check valves associated one each with each gas-receiving compartment and prd viding. for communication between the gas-receiving compartments and said expansion chamber, means for admitting liquefied gas under pressure to expand into said chamber, said check valves being operative to exhaust gas, which is in said chamber at a pressure reduced from the gas original pressure when in said liquefied state, into the gas-receiving compartments of the raft, each check valve comprising a bulkhead and a resilient diaphragm, the bulkhead being disposed between said expansion chamber and the gas-receiving compartment associated with said check valve, said bulkhead having an orifice therethrough surrounded by external sealing ribs on the compartment side of said bulkhead, and said resilient diaphragm normally abutting the edges of said ribs to close the valve but disengageable therefrom by gas pressure Within the expansion chamber greater than the gas pressures within the compartments by an amount as low as in the order of about .1 inch of mercury.

4. In a pneumatic life raft having a flotation member compartmented to define at least a pair of gas-receiving compartments, means on said life raft defining a preliminary expansion chamber adapted to communicate with said gas-receiving compartments, check valves associated one each with each gas-receiving compartment and providing for communication between the gas-receiving compartments and said expansion chamber, means for admitting liquefied gas under pressure to expand into said chamber, said preliminary expansion chamber being of a small volume relative to the volume of each of said gas-receiving compartments, said check valves being operative to exhaust gas, which is in said chamber at a pressure reduced from the gas original pressure when in said liquefied state, into the gas-receiving compartments of the raft, each check valve comprising a bulkhead and a resilient diaphragm, the bulkhead being disposed between said chamber and the gas-receiving compartment associated with said check valve, said bulkhead having an orifice therethrough surrounded by external sealing ribs on the compartment side of said bulkhead, and said resilient diaphragm normally abutting the edges of said ribs to close the valve but disengageable therefrom by gas pressures Within the expansion chamber greater than the gas pressures within the compartments.

. References Cited in the file of this patent UNITED STATES PATENTS 1,667,143 Luiz Apr. 24, 1928 2,173,567 Shafer Sept. 19, 1939 2,183,740 Fitch Dec. 19, 1939 2,208,181 Eggleston July 16, 1940 2,256,286 Johnston Sept. 16, 1941 2,359,843 Harris Oct. 10, 1944 2,444,717 Allen July 6, 1948 2,520,771 Martin Aug. 28, 1950 2,566,576 Marsh Sept. 4, 1951 FOREIGN PATENTS 48,105 Germany of 1889 331,629 Italy Nov. 11, 1935

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