US3062002A - Underwater propulsion system - Google Patents

Description

Nov. 6, 1962 R. c. SHA1-FER UNDERWATER PROPULSION SYSTEM Filed Aug. 9. 1960 www United States Patent 3,062,002 UNDERWATER PROPULSION SYSTEM Robert C. Shaffer, Torrance, Calif. (11465 Pinehurst Drive, Lakeside, Calif.) Filed Aug. 9, 1960, Ser. No. 48,437 12 Claims. (Cl. (S0-35.5)

This invention relates generally to fluid propulsion systems, and more particularly -relates to a fluid-powered drive unit for propelling a diver or a vehicle under water.

In recent years skin diving has become a wide-spread hobby. Usually the diver is equipped with a self-contained underwater breathing apparatus which supplies the diver with a breatheable gas at a pressure controlled by that of the ambient water. v Conventional gas tanks utilized for this purpose contain about 70 cubic feet of air which permits a diver to breathe for about one hour at the surface of the water and for lesser periods at a greater depth. Also physical exercise will increase the amount of breatheable gas required by the diver. Hence even if the diver takes along more than one tank of breatheable gas along with other underwater equipment the amount of time he can stay safely under water is strictly limited.

Accordingly, various attempts have been made to provide a diver with a self-propelled vehicle, such for example as a sled whereby the diver may carry more equipment including more tanks of air or other breatheable gas and hence may prolong his diving excursions. Thus it has been proposed to provide a battery-powered vehicle for a diver. However, an electric battery not only has a considerable weight which must be carried by the vehicle in addition to the diver, his other equipment and the tanks with the gas but the batteries must 'oe frequently recharged. As a result a small vehicle powered by an electric battery cannot operate long under water.

Accordingly, there is a need for a drive unit for propelling a vehicle or a diver and which may be powered to maneuver under water, which is light in weight and which can propel itself under water to carry a diver and his equipment for considerable periods of time.

A diver who carries a tank of breatheable gas such as air will use a very small quantity of the oxygen contained in the gas. For example, at the surface of the water 95% of the oxygen is not used by the diver and hence must be exhausted. As the diver descends into greater depths with correspondingly greater Water pressures, an even smaller quantity of oxygen is used by the diver due to the greater pressure of 4the gas supply, the remainder being discharged into the water. Since oxygen is a ready source of energyit would be very desirable to utilize the otherwise wasted quantities of oxygen and hence not only improve the eciency of the drive unit but also save weight because the gas is required in any case to permit the diver to breathe.

lt is accordingly an object of the present invention to provide an improved propulsion system adapted to propel a vehicle or a diver under Water.

Another object of the invention is to provide, in an underwater propulsion system, a closed liquid-vapor system which is heated by fuel burned by making use of the oxygen otherwise wasted by the diver in breathing.

A further object of the invention is to provide an improved, lightweight propulsion system adapted to propel an underwater vehicle or a diver which is eilicient and permits operation for many hours to allow a diver to stay under water for extended periods of time.

In accordance with the present invention there is provided au underwater drive unit which comprises a rigid cylinder having secured to the edges thereof a exible membrane to define a chamber of variable volume between the inner wall of the cylinder and the membrane. When this chamber is now cyclically expanded and contracted, water will be forced out of the cylinder and will ilow in again as the space defined by the membrane is reduced and increased in volume. Preferably, a clam shell valve is provided at one end of the cylinder which is periodically opened and closed to cause the water to i'low continuously in one direction through the cylinder,` thereby moving the cylinder in the opposite direction by reaction.

The drive unit is preferably actuated by aliquid-vapor system which is generated by burning a suitable fuel with the oxygen of the exhaust gas of the breathing apparatus of the diver. To tihs end there is preferably provided a closed water-steam system including novel check valves and a novel pump and valve system for circulating the water through the closed system.

yThese and other objects of the present invention will become more apparent as the description proceeds, taken in connection with the accompanying drawing in which:

=FlG. 1 is a schematic view, partly in section, of the propulsion system of the present invention; and

FIG. 2 is a sectional view of the check valve system for the drive unit of the system of FIG. 1 and illustrated in the intake position.

yReferring now to the drawing and particularly to FIG. l, there is illustrated an underwater propulsion system embodying the present invention. The system includes a drive or propulsion unit 10 and a closed liquid-vapor system 11 for actuating or operating the drive unit 10.

The liquid-vapor system 11 preferably operates by water and steam and includes a fuel tank 12 containing a suitable liquid or gaseous fuel, such for example as liquid propane. The propane tank 12 may contain enough gas to supply gaseous fuel for about four hours. A fuel line 13 connects the tank 12 to a combustion chamber 14 which may be closed at the top and bottom to prevent water from entering the combustion chamber, The burnt gases may leave the combustion chamber 14 by suitable means such as an opening 15 to prevent water from entering the combustion chamber 14. A suitable burner and pilot light 16 is connected to the fuel line 13 and extends into the combustion chamber 14. The com-v bustion chamber 14 may `be made of a suitable metal such as stainless steel. The main burner 16 may be used with a demand valve schematically indicated at 17 which meters the amount of fuel permitted to enter the combustion chamber 14 in accordance with the weight or mass of the air or combustible gas entering the combustion chamber. The air enters the combustion chamber 14 by means of an air line 18 and may -be supplied with either an oxygen containing gas or air in any suitable and desired manner. Preferably, however, the air line 18 is connected to the exhaust of a self-contained underwater breathing apparatus schematically illustrated at 19. By utilizing the exhaust gas from the breathing apparatus 19 there is a considerable savings in weight and an increase in etciency -because it is not necessary to carry an extra supply of oxygen.

In the combustion chamber 14 there is disposed a heating coil 20 connected to a water reservoir and steam dome 21. 'Ille bottom portion of the reservoir 21 is connected to the lower end of the heating coil 20 by a water pipe 22,. The pipe 22 may be provided with a check valve 23 which permits the flow of water from the reservoir 21 into the heating coil 20 but will prevent the ow of water or steam in the reverse direction. As shown at'24 the lower portion of the reservoir 21 is iilled with water. The upper end of the heating coil 2t) is connected by the pipe or conduit 25 to the steam pressure dome of the reservoir 21 and delivers, under operating conditions, wet steam into the steam dome.

The drive unit is connected to the steam dome 21 by another heating coil 26 disposed about the hot portion of the combustion chamber 14 and a steam line 27 for delivering the steam to the drive unit. The steam line 27 is connected to a check valve system 28 on the drive unit 10 which will be explained in more detail hereinafter. The check valve system 28 is controlled by the drive unit 10. The steam exhausted from the drive unit 10 then flows through a steam line 30 to a circulating pump unit generally indicated at 31. The pump unit includes a housing 32 which may also consist of stainless steel. The pump housing 32 has a rigid bottom cover 33 on which is mounted a exible bellows 34 which may be made, for example, of neoprene or other exible material. A branch 35 of the steam conduit 30 extends through the bottom portion 33 of housing 32 into the bellows 34. The upper or free end of the bellows 34 is closed. The bellows is spring-loaded by means of a spring 36 which bears between the upper cover 37 of the housing 32 and the bellows to urge the bellows into its compressed or retracted state.

The steam then ows from steam conduit 30 past the pump unit 31 and into a steam conduit 40 and thence through the inner sleeve 41 of a rst heat exchanger 45, through another steam conduit 42 into condenser 43 indicated schematically which is cooled by ambient water. From condenser 43 the condensed steam ilows as water through water conduit 46 into another check valve system 47 and thence into the outer sleeve 50 of the heat exchanger 45. The check valve system 47 has a branch 48 which connects it to the upper cover 37 of the housing 32 of the pump unit 31.

The check valve system 47 includes a rst valve body 51 which is in the portion of the water conduit upstream of the branch 48. The first valve body 51 has a seat 52 upstream of the valve body and a stop 53 disposed immediately upstream ofthe branch 48 and some distance `away from the seat 52. A second valve includes the second valve body 54 disposed downstream of the branch 48 having its valve seat 55 arranged upstream of the valve body 54. A suitable stop 56 is provided for the second valve body 54. It will thus be seen that if the pressure in the branch line 48 increases, valve 51 will be urged against its seat 52 while the valve body 54 will tend to open. On the other hand, an excess of pressure in the water line 46 will permit both valve bodies to open.

From the rst heat exchanger 45 the water now flows though water conduit 60 into the upper end of a second heat exchanger 61 which is disposed in the combustion chamber 14 and operates as a pre-heater. As illustrated the heat exchanger 61 preferably consists of a coil of pipe. The lower end ofthe heat exchanger 61 from which hot Water may be obtained is connected by means of a conduit 62 into the lower or water-lled portion 24 of the reservoir 21, thus completing the steam-water cycle.

The drive unit y10 and its associated valve system 28 will now be described. The drive unit 10 includes a rigid, hollow cylinder 65 which -rnay be made of a suitable metal such yas stainless steel. A tube or membrane 66 of a exible material is disposed within the hollow cylinder 65 and is normally spaced from the inner wall of the cylinder 65 as indicated by the full lines. The tube 66 is turned over the edges of `the cylinder 65 as shown at 67 and forms a water-tight seal with the cylinder. To this end the overturned portion 67 of the tube 66 may be glued or bonded to the cylinder, or a suitable ring 68 may be put over the overturned portion 67 to secure a tight seal. The tube 66 may be made, for example, of neoprene. An air-tight chamber 69 is thus formed between the inner wall of the cylinder 65 and the tube 66. Since the tube 66 is flexible, the volume of the chamber 69 may be increased or decreased.

A clam shell valve 70 is disposed at one of the open 4 ends of the tube 66 and is arranged to open or close the left-hand end of the drive unit 10. The clam shell valve 70 is pivoted at 71 and has two members 72 and 73 which close the end of the 'tube 66. The ends of the two valve members 72, 73 adjacent to the tube 66 are secured to the tube by a flexible tube 74 which extends over the tube 66 as shown and is held, for example, to the valve 70 by a Wire or ring 75 and to 'the tube 66 by another wire or ring 76. The exible tube 74 is so disposed and arranged that the clam shell valve 70 is normally closed as shown by ythe solid lines of the drawing. How ever, a slight water pressure from the right or interior of the tube 66 is sufficient to force the valve open and permit Ithe water to llow inthe direction of the arrows 77.

The check valve system 28, which will now be described, is operated by the movements of the membrane or exible tube 66 through -a mechanical linkage. At the downstream portion of the conduit 27 connecting the steam generator to the drive unit there is provided a first valve including `a valve member 78 having a valve seat 80. The iirst valve is provided in `a conduit 81 which connects the conduit 27 to the conduit 30 leading to the circulating pump 31. A second conduit 82 is provided as a branch line to house part of the mechanical linkage to be presently described, while a third conduit 83 connects to the chamber 69. The second valve of the check valve system 28 includes a valve body 85 having a seat 86 disposed upstream of the conduit 30. A selector valve body 88 has a function of forcing either the valve body 78 or the valve body 85 from their respective seats to keep them open. To this end the valve body 88 has a rod 90 at its upper end. Hence when the check valve system is in the position illustrated in FIG. 2 Ithe valve body 78 is forced from its seat to permit steam to enter the chamber 69. The lower end of the selector valve body 88 is provided with a nger-like extension 91 which engages the valve body `85 when the selector valve 88 is in its lower position (illustrated in FIG. 1) to keep the valve body 85 from its seat 86.

The positions of the selector valve body 88 are controlled by a linkage 92 which is connected to the flexible tube 66 and moves in unison therewith. To this end the tube 66 is provided with a pressure foot 93 to which is connected a rod 94 extending through conduit 83. The rod 94 bears against a compression spring 95, the tension of which may be adjusted by the threaded cover 96 closing the conduit 83. A first link 98 is pivoted at 97 to the rod 94 and has a hollow opening into which extends a rod 100 which is permitted to move into the opening in the link 98. A spring 101 bears against another link 1102 and extends into the opening of Ithe link 98 to provide a positive connection between the individual links. The link 102 is pivoted at 103 and has a free end 104 which extends into a suitable recess of the selector valve 88.

The operation of the propulsion system of the invention will now be explained. Steam is initially generated by -opening the valve 17 to admit fuel from the fuel tank 12 into the combustion chamber 14. The fuel is ignited by the pilot light ora suitable catalyst. In order to maintain combustion, oxygen is required which is delivered into the combustion chamber 14 by means of the air line 18 from a supply 19 of oxygen-containing gas or air which may be the exhaust from a self-contained underwater breathing device of conventional design. Thus the combustion chamber 14 is heated and the water contained in the heating coil 20 is heated as the water circulates from the lower portion 24 of the water reservoir and steam dome 21 through the coil 20 back into the upper portion of the water reservoir and steam dome. Eventually wet steam is generated and collects in the upper steam portion of the dome 21 to force the water from the lower water portion of the dome 21, `aided by gravity, past the check valve 23 back into the heating coil 20. The steam chamber.

now enters the heating coil 26 from the top of the steam dome 21 to be converted into superheated steam. As mentioned previously, the check valve 23 prevents water from flowing back into the reservoir portion of dome 21 but permits free llow `of water into the heating coil to permit continuous generation of steam.

Initially, that is, at the start of the operation of the system, the clam shell valve 70 is closed slightly by the action of its fastening tube 74. At the same time the flexible tube 66 is essentially collapsed as shown in clot and dash lines because the pressure in the entire steamwater system is lower than the ambient pressure. As a result the check valve system 28 is in the position shown in FIG. 2. Hence the valve body 78 is forced oil its seat to permit the `steam which is now being generated to tlow from the second heating coil 26, conduit 27 past valve seat 80 through conduits 81, 82, v83 into chamber 69. The steam pressure will also force valve body 85 into its closed position thus preventing the steam from flowing into conduit 30; The steam pressure further forces the tube 66 away from the cylinder 65 until the tube assumes the shape shown in solid lines. It will be apparent that this action ywill not take place until the steam pressure exceeds the ambient pressure because in expanding the chamber 69 the steam must overcome the Iwater pressure. The water previously contained in the open space between the flexible tube 66 is now expelled at the open ends of the cylinder 65 and will force open the clam shell valve 70.

When the tube 66 is fully expanded, all the water within the tube has been expelled and the water pressure acting against the clam shell Valve 70 tending to open it is reduced, hence permitting the shell valve to close again.

At the same time the expansion of the tube 66 into the position shown in full -lines has pulled the rod 94 into its lower position. Therefore, the links 98 and 102 rotate about the pivot 163 with the result that the selector valve body 88 suddenly snaps into its lower position shown in FIG. l. During this movement rod 100 is permitted to move into the opening in link 98. With the selector valve body 88 in its lower position, valve body 85 is now forced off its seat 86. As a result the steam in chamber 69 is now permitted to ow past valve seat 86 and conduit 30 into the circulating pump 31 and beyond. vThe suddenly reduced pressure in conduit 81 now forces vvalve body 78 against its seat thus preventing further steam from flowing into chamber 69.

The steam thus exhausted from chamber 69 into conduit 30 causes a momentary rise of pressure in the conduit and hence expands bellows 34 momentarily against the action of its spring 36. Accordingly, the water in the upper'portion of the pump housing 32 is forced out of the housing through the branch conduit 48 and into the valve chamber. Since the stop 53 of the valve body 61 is relatively far away from the seat 52 of the valve body 51, the closing of the valve body against its seat 52 is delayed in spite of a relatively rapid movement of the valve body. At the same time the valve body 54 is forced away from its seat 55 to permit llow of the condensed water from the condenser coils and from the pump housing into the outer sleeve 50 of the heat exchanger. Thus a small portion of the water is rammed by inertia into the outer sleeve.

The remainder of the steam from chamber 69 is rapidly condensed as it liows from conduit 30 through the inner sleeve 41 of the heat exchanger 45 into the condenser coils 43. As the water llows along the outer sleeve 50 it is heated in counter-current ow by the steam owing in the inner sleeve of the heat exchanger.

From the outer sleeve 50 of the heat exchanger 45 the water now flows into the second heat exchanger or preheater 61 where the water is further heated in countercurrent flow by the hot gases in the combustion The thus preheated water is then returned by means of the conduit 62 into the lower portion 24 of the reservoir and steam dome 21 thus completing its cycle.

The burnt hot gases from the combustion chamber 14 are released into the ambient water to prevent water from entering the combustion chamber during operation of the system.

The steam-water system is initially filled with water and then exhausted by a suitable pump to a pressure of about 2 inches of mercury which corresponds to a vapor pressure of water at about F. Alternatively, steam may be initially introduced into the system. Then the entire steam-water system may be immersed in an epoxy resin to seal any leak that may be present. The resin may then be set to seal all leaks and the system is ready for operation.

Except for the condenser coils 43 and the circulating pump 31 which are in contact with the ambient water, the remainder of the water-steam system should be carefully insulated from the water to avoid heat losses. To this end all valves, the reservoir and all conduits should be carefully heat insulated. This may be accomplished, for example, by protecting all parts with a material such as neoprene. In particular the superheated steam generated by the steam generator must be protected from heat losses by suitable heat insulation of all steam conduits.

The operation of the drive unit 16 will now be explained. As set forth hereinabove, when the steam generator is started, the valve 70 is initially closed. Also the tube 66 is collapsed, thus permitting steam to enter the chamber of the drive unit. The resulting expansion of the tube 66 forces the water within the tube 66 outV at both ends of the cylinder and opens the valve 70. Subsequently, as already explained, the steam is exhausted from the chamber in the drive unit into the circulating pump and the condenser. As a result the ytube 66 tends to collapse again thus forcing water into the open space within the tube 66. Since the valve 70 is now closed, the water can only enter the cylinder through the right-hand open end thereof.

As previously explained, the chamber 69 is exhausted into the conduit 30 and condenser 43. As a result the tube 66 tends to collapse into the position shown in dot and'dash lines. As soon as the tube 66 approaches its dot and dash or collapsed position the selector valve body snaps into its upper position of FIG. 2. Consequently Valve body 78 is forced off its seat 80 to permit steam to enter chamber 69. The steam prsesure, in turn, forces valve body 85 against its seat 86 and another cycle of operation starts again.

The water in tube 66 is forced out past clam shell valve 70 which opens under the increased pressure. Thus the water tends to llow in the direction of the arrows 77. The cylinder will be propelled through the water by reaction force in a direction opposite to thatot the water flow as shown by arrow 64. Hence any equipment connected to the drive unit or a diver secured to the drive unit will be propelled similarly.

Thus the operation of the drive unit 10 is as follows. Assume that the drive unit is initially in the position shown in FIG. l where membrane 66 is partially expanded to provide a relatively small space for the water. Next, a vacuum created in the steam-water system pulls the membrane 66 towards the inner walls of tube 65. Water now rushes into the void thus created. This water can only flow into the space formed by the walls of membrane 66 from the right of FIG. l because the clam shell valve is closed. If the clam shell valve 70 were not closed, or not fully closed, the pressure of water attempting to ow from the left into the drive unit 10 would quickly close the valve 74) fully.

Due to inertia, the water flowing from the right to the left in the direction of arrows 77 will continue to flow in the same direction and forces open clam shell valve 70. After the membrane 66 has assumed its dot and dash position adjacent the inner wall of tube 65, steam is forced into the chamber 69. This action now expands the membrane 66 and displaces the Water in the tube. Due to inertia the water continues to iiow in the same direction, that is, in the direction of arrows 77. During this time the clam shell valve is forced open.

Finally the vacuum which is then again created in chamber 69 forces the membrane 66 outwardly to the dot and dash position and water again rushes into the thus formed void. Any water which might attempt to flow from left to right tends to close the valve '70 so that the water is forced to iiow from right to left as shown by arrows 77.

It will thus be seen that the main function of clam shell valve 70 is to prevent water from flowing into the left end of the drive unit when a void is formed by contraction of the membrane. Furthermore, it is important to note that the water flows into a void and need not displace water already in the drive unit. This factor contributes to a better eiciency of the propulsion system of the invention.

There has thus been disclosed an underwater propulsion system which is comparatively light in weight and will permit operation under water for many hours. The propulsion system of the invention is adapted, to propel a suitable underwater vehicle or may directly carry a diver, his breatheable gas supply, other equipment and the necessary fuel. The fuel is preferably oxidized by means of the exhaust gas discharged from an under- `water breathing device, thus eliminating the waste of oxygen and reducing the weight of the equipment needed to power the propulsion system of the invention. The .system of the invention utilizes a closed liquid-vapor system which makes it unnecessary to replenish the boiler fluid.

What is claimed is:

1. An underwater propulsion system comprising a hollow rigid cylinder of circular cross-section adapted to be propelled under water, a flexible member symmetrically disposed Within said cylinder and normally spaced from the inner wall of said cylinder, said member extending over the edges of said cylinder and forming a Water-tight seal with said edges to provide an annular chamber of variable volume defined by said member and the inner wall of said cylinder, means for cyclically allowing fluid 1o enter said chamber and withdrawing it again, and a `separate valve secured to one open end of said cylinder for cyclically opening and closing said open end, whereby, when said system is immersed in water, a column of water is forced by the cyclic expansion and retraction of said member through said cylinder under .the control of said valve to propel said cylinder in a direction opposite to that of the iiow of said column of water.

2. An underwater propulsion system for propelling a diver having `an underwater breathing device delivering exhaust air expelled by the diver, said system comprising a hollow rigid body; a exible member disposed within said body and secured thereto to form a water-tight charnber of variable volume defined by the inner wall of said body and said member; a closed liquid-vapor system for periodically expanding and contracting said chamber, and including means for permitting vapor to enter said chamber and to withdraw vapor from said chamber; a supply of oxidizable fuel, a combustion chamber connected to said supply for burning the fuel to heat liquid to obtain vapor; and means for delivering the exhaust air from the breathing device expelled by the diver into said combustion chamber to burn the fuel.

`3. An underwater propulsion system comprising a hollow, rigid body, a flexible membrane extending over the inner wall of said body and secured to the edges thereof to form a chamber of variable volume defined by said inner Wall and said membrane; a closed steam-water system for periodically increasing and decreasing the volume of said chamber, Said steam-water system including a steam generator; a gate valve disposed on one open end of said body and adapted to open or close said open end; said closed steam-Water system including in series connection a check valve system associated with said chamber, and a pump, said check valve system including a first valve for controlling the flow of steam from said generator to said chamber, and a second valve for controlling the ow of steam from said chamber to said pump, and a mechanical linkage coupled between said membrane and said valves to force said rst valve into 4the open position when said membrane is contracted, thereby permitting steam to flow into said chamber to force said second valve into the closed position and to expel fluid from the space formed by said membrane past said open gate valve, said linkage being arranged to force said second valve into its open position when said membrane is expanded, thereby permitting steam to flow from said chamber to said pump, and to force said first valve into its closed position.

4. An underwater propulsion system comprising a hollow, r-igid body, a flexible membrane extending over the inner wall of said -body and secured to the edges thereof to form a chamber of variable volume defined by said inner wall and said membrane; a closedv steam-water systern for periodically expanding and contracting the volume of said chamber, said steam-water system including a steam generator; a valve disposed on one open end of said body and adapted to open or close said open end; said closed steam-water system including in series connection a check valve system, a pump and a condenser, said check valve system including a rst valve member and seat therefor for controlling the ow of steam from said generator to said chamber, and a second valve member and seat therefor for controlling the ow of steam from said chamber to said pump, a selector valve body, a mechanical linkage coupled to said membrane and movable therewith for moving said selector valve body; said selector valve body being disposed to force said first valve member into the open position when said membrane contracts, thereby permitting steam to flow into said chamber to force said second valve member into the closed position and to expel fluid from the space formed by said membrane past said open valve, said selector valve body being disposed to force said second valve member into its open position when said membrane expands, thereby permitting steam to ow from said chamber to said pump, said first valve member being forced into its closed position by the pressure differential created thereby, the steam flowing from the chamber and said check valve system into said condenser, said pump being actuated by flow of iiuid from said chamber to force fluid from said chamber back into said steam generator.

5. An underwater propulsion system comprising a hollow, rigid body, a flexible membrane extending over an inner wall of said body and secured to the edges thereof to form a first chamber of variable volume defined by said inner wall and said membrane, a closed steam-water system for periodically increasing and decreasing the volume of said first chamber, said steam-water system including a steam generator, a valve disposed on one open end of said body and adapted to open or close said open end, said closed steam-water system further including in series connection a pump, a condenser, a check valve system, and a heat exchanger arranged down-stream from said steam generator; means coupled to said membrane and responsive to the movements thereof for periodically supplying steam from said generator to said first chamber and for allowing steam to flow from said first chamber -to said pump; the steam owing from the chamber through a branch of said heat exchanger into said condenser and then to said check valve system, said pump being actuated by flow of uid from said chamber, said pump including a housing, a bellows in said housing communicating with said first chamber, a second expansible chamber defined by said housing and bellows, said check valve system having a first valve body and seat therefor and a second valve body and seat therefor, said first valve body controlling fluid ow lfrom said condenser to said second chamber and said second valve body controlling fluid flow from said second chamber to the other branch of said heat exchanger, said check valve system being arranged so that operation of said pump closes said first valve body and opens said second valve body to force fluid from said second chamber into said heat exchanger.

6. An underwater propulsion system comprising ya hollow, rigid body, a fiexible membrane extending over the inner Wall of said body and secured to the edges thereof to form a chamber of variable volume defined by said inner wall and said membrane; a closed steam-water system for periodically increasing and decreasing the volume of said chamber, said s-team-Water system including a steam generator; a combustion chamber adjacent said steam generator, a supply of oxidizable fuel, means for supplying the fuel and air to said combustion chamber to vaporize .the water into steam; a valve disposed on one open end of said body and adapted to open or close said open end; a rst check valve system, a second check valve system, a pump, a condenser, a first and a second hea-t exchanger arranged serially and downstream from said steam generator, means coupling said membrane to said first check valve system and responsive to expansion and contraction of said membrane for periodically permitting the flow of steam from said generator to said chamber and permitting thereafter the ow of steam from said chamber to said pump, the steam fiowing from the chamber and said first check Valve system through said first heat. exchanger `into said condenser and then to said second check valve system, said pump being actuated by flow of fluid from said chamber for permitting periodically fiuid flow from said condenser to said second heat exchanger, said second heat exchanger being disposed in said combustion chamber to preheat the fluid therein, and a return connection from said second heat exchanger to said steam generator.

7. An underwater propulsion system comprising a hollow, rigid body, a flexible membrane extending over the inner wall of said body and secured to the edges thereof to form a chamber of variable volume defined by said inner wall and said membrane; a closed steam water system for periodically increasing and decreasing the volume of said chamber, said steam-water system including a steam generator; a combustion chamber adjacent said steam generator, a supply of oxidizable fuel, means for supplying the fuel and air to said combustion chamber to vaporize the water into steam; a clam shell valve disposed on one open end of said body and adapted to open or close said open end; said closed system further including in series connection a first check Valve system, a second check valve system, a pump, a condenser, a first and a second heat exchanger arranged downstream from said steam generator, said first check valve system including a first valve member and seat therefor for controlling the flow of steam from said generator to said chamber, and a second valve member and seat therefor for controlling the ow of steam from said chamber to said pump, a mechanical linkage connected to and movable with said membrane and having a selector Valve body movable with said membrane and linkage, said selector valve body being disposed to force said first valve member into the open position when said membrane is collapsed, thereby permitting steam to flow into said chamber to expel uid from the space formed by said membrane past said open clam shell valve, said second valve member lbeing forced into the closed position by the pressure differential thereacross, said selector valve body being disposed to force said second valve member into its open position when said membrane is expanded, thereby permitting steam to flow from said chamber to said pump, said first valve member being forced into its closed position by the pressure differential thereacross, the steam l0 fiowing from the chamber and said first check valve system through said first heat exchanger into said condenser and then to said second check valve system, said pump being actuated by flow of fluid from said chamber, said second check valve system having a third valve body and seat therefor and a fourth valve body and seat therefor, a second chamber in communication with said pump and second check valve system, said third valve body controlling uid flow from said condenser to said second chamber, and said fourth valve body controlling fluid ow from said second chamber to said second heat exchanger, said second check valve system being arranged so that operation of said pump closes said third valve body and opens said fourth valve body to force fiuid from said second chamber into said second heat exchanger, said second heat exchanger being disposed in said combustion chamber to preheat the fluid therein, and a return connection from said second heat exchanger to said steam generator.

8. In an underwater propulsion of the type including a rigid hollow cylinder, and a flexible membrane disposed in said cylinder and secured to the edges thereof to fonn a chamber of variable volume; a check valve system for cyclically permitting iiuid to flow from a generator into said chamber to cause expansion of the chamber and to permit the fluid to exhaust from the chamber into a reservoir to cause collapse of the chamber, said check valve system including a conduit adapted to convey fluid from the generator to the chamber and from the chamber to the reservoir, a first valve member for controlling the uid fiowing into the chamber, a second valve member for controlling the fiuid flowing from the chamber, a selector valve body for forcing either said first or said second valve body into is open position, and a mechanical linkage secured to and movable with said membrane and controlling the position of said selector valve body, said selector valve body being arranged to maintain said first valve member open when said membrane is collapsed while the fiuid pressure is forcing said second valve member into its closed position, said selector valve ybody being further arranged to maintain said second valve member open when said membrance is expanded While the fluid pressure is forcing said first valve member into its closed position.

9. In an underwater propulsion system of the type including a rigid hollow cylinder, and a iiexible membrane disposed in said cylinder and secured to the edges thereof to form a chamber of variable volume: a clam shell valve secured to one open end of the cylinder; and a check valve system for cyclically permitting fiuid to flow from a generator into said chamber to expand the chamber, and to permit the fluid to exhaust from the chamber into a reservoir to collapse the chamber, said check valve system including a conduit adapted to convey fiuid from the generator to the chamber and from the chamber to the reservoir, a first valve member having a seat therefor disposed downstream yfrom the generator for controlling the fluid flowing into the chamber, a second valve member having a seat therefor disposed downstream from the chamber for controlling the fiuid owing from the chamber, a selector valve body, and a mechanical linkage secured to said membrane and movable in unison therewith and controlling the position of said selector valve body, said selector valve body being arranged to urge said first valve member away from its seat when said membrane is collapsed while the Huid pressure is forcing said second valve member against its seat, and said selector valve body being further arranged to urge said second valve member away from its seat when said membrane is expanded while the fluid pressure is forcing said first valve member against its seat.

10. In a closed steam-water system, an intermittent supply of steam; a circulating pump, a check valve system communicating with said supply; and a steam generator downstream of said check valve system, said pump having a housing, a bellows communicating with said supply, and disposed in said housing to dene a chamber having a volume variable by said bellows, said check valve system communicating with said chamber and including a rst valve body and a seat therefor for controlling the uid ow from said supply to said chamber, the seat for said rst valve lbody being disposed upstream of said chamber, and a second valve body and a seat therefor disposed downstream of said chamber for controlling the ow of uid from said chamber to said generator, whereby an increase of pressure in said bellows causes eX- pansion of said bellows and a decrease of the volume of said chamber to cause in turn said rst valve body to move towards its seat and said second valve body to move away from its seat, thereby to cause flow of fluid from said supply to said generator.

11. In a closed steam-water system, an intermittent supply of steam; a circulating pump; a condenser; a check valve system; and a steam generator downstream of said check valve system, said pump having a housing, a bellows disposed in said housing and communicating with said supply to dene a chamber having a volume variable by said bellows, said check valve system communicating with said chamber and including a rst valve body and a seat therefor for controlling the uid ow from said condenser to said chamber, the seat for said first valve body being disposed upstream of said chamber, and a second valve body and a seat therefor downstream of said chamber for controlling the tlow of fluid from said chamber to said generator, whereby an increase of pressure in said bellows causes expansion of said bellows and a decrease of the volume of said chamber to cause in turn said rst valve body to move towards its seat and said second valve body to move away from its 12 seat, thereby to cause ow of fluid from said condenser to said generator.

12. In a closed steam-water system, an intermittent supply of steam; a circulating pump, a heat exchanger having an inner sleeve and an outer sleeve, said inner sleeve being disposed downstream of said supply; a condenser; a check valve system downstream of said inner sleeve and communicating with said outer sleeve; and a steam generator downstream of said outer sleeve, said pump having a housing, a bellows communicating with said supply and disposed in said housing to define a chamber having a volume variable by said bellows, said check valve system communicating with said chamber and including a rst valve body and a seat therefor for controlling the fluid flow from said condenser to said chamber, the seat for said rst valve body being disposed upstream of said chamber, and a second valve body and a seat therefor downstream of said chamber for controlling the flow ot uid from said chamber to said outer sleeve, whereby an increase of pressure in said bellows causes expansion of said bellows and -a decrease of the volume of said chamber to cause in turn said rst valve body to move towards its seat and said second valve body to move `away from its seat, thereby to cause flow of tiuid from said condenser to said generator.

References Cited in the tile of this patent UNITED STATES PATENTS 1,282,145 Tobler Oct. 22, 1918 2,089,853 Nelson Aug. 10, 1937 2,291,912 Meyers Aug. 4, 1942 2,722,021 Keogh-Dwyer Nov. 1, 1955

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