US3526223A

US3526223A - Space suit and membrane pump system therefor

Info

Publication number: US3526223A
Application number: US488367A
Authority: US
Inventors: Daniel Lee Curtis
Original assignee: Litton Systems Inc
Current assignee: Northrop Grumman Guidance and Electronics Co Inc
Priority date: 1965-09-20
Filing date: 1965-09-20
Publication date: 1970-09-01
Anticipated expiration: 1987-09-01
Also published as: SE319085B; DE1653505A1; GB1125090A

Description

United States Patent [72] Inventor Daniel Lee Curtis Manhattan Beach, California [21] Appl. No. 488,367 [22] Filed Sept. 20, 1965 [45] Patented Sept. 1, 1970 [73] Assignee Litton Systems Inc.

Beverly Hills, California [54] SPACE SUlT AND MEMBRANE PUMP SYSTEM THEREFOR 18 Claims, 7 Drawing Figs.

[52] US. Cl 128/1425. 92/80. 92/107: 103/150: 62/259.2/81 [51] Int.Cl A62b 7/14 [50] Field ofSearch 128/140, 142.5,142,142.4,145.5,145.6,191,399,400, 402;62/259,402;98/1.5,103/148,150,152,440; 230/160.161.163,164;2/2.1.81: l65/(1nquired) 92/80, 107; 137/63R,64 (Digest) [56] References Cited UNITED STATES PATENTS 1,282,145 10/1918 Tobler 103/152 Primary ExaminerWilliam E. Kamm Arrorney- Robert H. Lentz. Alan C. Pose, Alfred B. Levine andJohn B. MillerJr.

ABSTRACT: A fluid pump comprising an outer casing having two internal diameters to provide an annular step and a flexible tubular membrane positioned within said outer casing. A passive fluid flows within the flexible tubular membrane and a pumping fluid passes between the inner wall of the outer casing and the flexible tubular membrane. The flexible tubular membrane in its expanded position provides a fluid seal for the pumping fluid along the inner wall ofthe casing and the annular step. Compression and the expansion ofthe flexible tubular membrane, due to the pressure differential between the two aforementioned fluids, allows the passive fluid and the pumping fluid to be successively expelled from the pump upon the closing and opening ofthe fluid seal, respectively.

Pa tented Sept. 1, 1970 Sheet MM N a w W 5 3 MN Q h mm S J mm J \vM v n O\ WVVv-////// ///////V7 N/ Q \1 ll Patented Sept. 1, 1970 Sheet 3 of 3 SPACE SUIT AND MEMBRANE PUMP SYSTEM THEREFOR This invention relates generally to a fluid pump apparatus and, more particularly, to apparatus in which one fluid is pumped by the action of another fluid. The invention provides a pump that moves fluid material by an action closely akin to peristalsis, that is, where the contents of a membrane within the pump is forced onward by successive membrane contractlons.

Recent advances have been made in the arts of pure fluid devices and in protective suits for pilots and other personnel who occupy non-pressurized cabins of 'vehicles that operate at altitudes greater than 12 miles above sea level. Such advances as these have demonstrated a need for a simplified. light weight, and reliable fluid pump that has relatively few moving parts and that is not dependent upon a source of electrical energy for power. One of the major problems heretofore encountered in the attempts to meet these needs has been the inability of such a pumping device to be disassociated entirely from a source of electrical energy.

For example, fluid pumps have been proposed wherein one fluid (the pumping fluid) is used to move another fluid. Among the pumps that fall within this category are those which comprise a rigid outer casing having a flexible-walled conduit positioned therein as an inner lining. The fluid to be pumped (the passive fluid) flows through the flexible-walled conduit, while the pumping fluid is forced into the annular volume between the flexible-walled conduit and the inner surface of the casing. Such pumps are peristaltic in nature in that the passive fluid is pumped by sequentially compressing (by means of the pumping fluid pressure) the flexible-walled conduit containing the passive fluid.

Although prior art peristaltic pumps have been found to perform reasonable well in many applications, there are several disadvantages attendant their use. First, it is not unusual to find that more than one of the casing-conduit assemblies described above are needed to constitute the pump. In such an event, the casings are normally connected end-toend, and the peristaltic action is created by an external control valveor an auxiliary pump which causes pumping fluid to be supplied cyclically to one of the casing-conduit assemblies at a time. Obviously, a fluid pump in this configuration is rather cumbersome and has an excessive number of moving parts. Second, in prior art fluid pumps having but one casing-conduit assembly, the peristaltic action is created either by an external control valve or by travelling pressure waves in the pumping fluid which are generated by an external source of sinusoidal pressure. So that travelling pressure waves may be used to compress the flexible conduit within the casing, the conduit is described as being composed of two materials of widely different moduli of elasticity, thus further complicating the construction of the pump. Moreover, both ofthe aforementioned fluid pumps of the prior art have been described in the literature as requiring an auxiliary motor-driven pump for circulating the pumping fluid through the casing-conduit assembly or for creating the travelling pressure waves. This requirement makes the fluid pumps dependent upon some other motordriven pump and precludes their use where, for reasons of size, weight, the unavailability of electricty, or for other reasons, motors of any type cannot be used.

Another type of fluid pump, not of the character described above, has been proposed in an attempt to eliminate the requirement of an auxiliary motor power source by using fluid power to operate the fluid pump. The pump comprises generally a casing divided by a flexible member. The passive fluid is injected into the lower one-half of the casing, the socalled flow chamber. External valve means are used to produce cyclic fluid pressure fluctuations in the top half of the casing, termed the pumping chamber. The cyclic pressure fluctuations cause a deformation of the member dividing the casing, causing passive fluid to be drawn into and expelled from the flow chamber. Hydrostatic heads of pumping fluid such as waterfalls, compressed gas, pressurized pipelines, and

the like, have been proposed as sources of fluid pressure for the pumping chamber. However, even though such power sources have been employed with minor success with this prior art pump, they have not successfully provided a truly self-contained fluid pump since external valving still has been required to cause fluctuations in the pressure. The need for these auxiliary controls has detracted substantially from the usefulness of the pump.

it is, therefore, an object of the present invention to provide a fluid pump that does not require the use of external motors, relief valves or pumps for its operation.

Another object of the invention is to provide an improved fluid pump that is operated by a fluid source of substantially constant pressure.

It is a further object of the invention to provide a fluid pump having relatively few moving parts, which is easily manufactured, and which will have an extremely long and useful life.

It is still another object of the invention to provide a fluid pump for moving one fluid by means of a pressure differential existing between said one fluid and a second fluid.

Another object of the present invention is to provide a selfcontained fluid pump that is peristaltic in nature, in that a first material is moved onward by compressing a flexible tubular membrane containing the first material by means of pressure in a second material.

A further object of the invention is to provide a fluid pump system for space enclosures in which fluid, such as coolant fluid, is pumped by means of fluid gas supplied to the space enclosure.

These and other objects are accomplished in accordance with an illustrative embodiment of the invention by a fluid pump employing an outer casing having a variable internal volume and a flexible tubular membrane positioned therein that extends the length of the casing. The tubular membrane serves as a barrier between the pumping fluid,and the passive fluid to be pumped. Also, the membrane serves to intermit tently valve the flow of pumping fluid, as will be pointed out in greater detail hereinafter. Suffice it to say that, in its expanded condition, the tubular membrane provides a fluid seal for the pumping fluid. Fluid to be pumped (passive fluid) enters the casing and passes through the tubular membrane, whereas the pumping fluid enters the casing and passes between the tubular membrane and the inner surface ofthe casing. Within the described embodiment of the present invention,

pumping of passive fluid (a coolant stored within a fluid reservoir) through a protective suit (hereinafter called a space suit) is accomplished by connecting an inlet end of the pump casing to the passive fluid reservoir and an outlet end of the pump casing to the space suit. A pumping fluid inlet' pipe in-' terconnects a fluid source of constant pressure and the pump casing, and an exhaust pipe couples the pump-casing to the space suit wherein the pumping fluid is used as the oxygen supplied to the occupant of the suit. Compression of the tubular membrane, due to the difference between the pressures of the pumping fluid and the passive fluid, forces the passive fluid to exit the pump in a direction of flow determined by two check valves.

Assume that the pumping fluid is the gas oxygen, and that the membrane is filled with a liquid type of passive fluid. The tubular membrane is thereby inflated to its maximum dimension, as limited by-the internal wall of the casing. An effective gas seal is formed by the membrane against the inner wall of the pump casing, and gas flow into the pump from the constant pressure source is trapped causing the gas pressure in the pump to increase. As the gas pressure increases, it becomes greater than the liquid pressure so as to cause the tubular membrane to collapse and pump the liquid contained therein pressure of the respiratoryforcing it to re-expand. The pumping action is ready to be repeated.

Broadly, then, one may readily perceive that the present invention provides a self-contained fluid pump comprising a pump casing, having inlet and outlet ports therein, through which a first fluid may pass. A flexible walled chamber, positioned within the pump casing, has openings to the outside of the pump so that a second fluid may pass therethrough. When a second fluid fills the flexible walled chamber, the wall of the flexible chamber becomes fully distended and covers the outlet port, thereby inhibiting the flow of the first fluid through the pump casing so that the pressure of the first fluid within the casing will increase. Because the first fluid is supplied to the pump at a substantially constant pressure, the pressure of the first fluid trapped within the casing rises and compresses the flexible walled chamber, forcing the second fluid out of the flexible chamber. Thus, this extremely simplified and reliable fluid pump is particularly adaptable for use, for example, as an artificial heart pump or in space suit applications for pumping blood or coolant fluid, respectively, by means of the power derived from the expansion of compressed oxygen normally used to supply respiratory gas to the patient or suit inhabitant.

By making the expanding compressed oxygen do the work of pumping a coolant to a space suit, for example, energy is taken from the compressed oxygen, thereby lowering slightly the temperature of the oxygen supplied to the space suit from the exhaust pipe of the pump. This is advantageous since the cooler respiratory gas cooperates with the coolant to keep the suit inhabitant at a lower ambient temperature within his space suit.

These and other advantages and features which are believed to be characteristic of the present invention, both as to its organization and method of operation, will be better understood from the following description considered in connection with the accompanying drawings in which one embodiment of the present invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.

In the drawings:

FIG. 1 is a diagrammatic view ofa pumping system embodying a fluid pump of the present invention;

FIG. 2 is a cross-sectional view ofa fluid pump constructed in accordance with teachings ofthe invention;

FIG. 3 is a cross-sectional view of the fluid pump illustrated in FIG. 2, the pump being shown at a different interval of operation;

FIG. 4 is a cross-sectional view of the fluid pump illustrated in FIG. 2, the pump being shown at a still different interval of operation;

FIG. Sis a diagrammatic view ofa pumping system employing two of the'fluid pumps of the present invention connected in parallel;

FIG. 5a is a cross-sectional view of an alternate embodiment of pumping fluid diverter that may be used in the pumping systems illustrated in FIGS. 5 and 6; and

FIG. 6 is a diagrammatic view ofa pumping system employing two of the fluid pumps of the present invention connected in series.

With reference now to the drawings, wherein like or corresponding parts are designated by the same reference characters throughout the several views, there is diagrammatically illustrated in FIG. 1 a pumping system employing a pump 10 to move a passive fluid (for example, a liquid coolant) from a reservoir 40 through a space suit 50 by means of power supplied by a pumping fluid (for example, a compressed gas such as oxygen) contained within a bottle 60. Pumping fluid is supplied to the pump 10 through a fluid conduit 62 connected to an inlet pipe 24 of the pump 10 through a constant pressure outlet valve 64 which assures a substantially constant pressure cp. to the pipe 24. It may be seen that the passive fluid flows from the reservoir 40 to the pump 10 through a fluid conduit 29 which is coupled to an inlet pipe 14 by a check valve 20. A pressure is maintained on the passive fluid by a cylinder 131 within the reservoir 40 pushed downwardly by a spring 130.

The passive fluid is expelled from the pump 10 through an outlet pipe 16 to the space suit 50 through a check valve 30, coupled to the space suit 50 by a fluid conduit 31. The pump 10 is also connected to the space suit 50 by an exhaust pipe 26 through which the pumping fluid escapes the pump 10 for supplying oxygen as the respiratory gas for the suit inhabitant.

It will be noted that the space suit 50 is diagrammatically illustrated to have an inner chamber 92 in which the suit inhabitant would be positioned and to which the respiratory gas is supplied through a connector 93. Gas is exhausted from the space suit 50 through an over-pressure exhaust vent 63 in the helmet thereof. The space suit 50 is also shown to include a coolant garment as an integral part thereof. The passive fluid coolant is supplied to the coolant garment 90 through a connector 94 to which the fluid conduit 31 is coupled. The passive fluid exits the coolant garment 90 of the space suit 50 through a fluid conduit 91 which is coupled to the reservoir 40.

One skilled in the art will readily perceive, from the description which hereinafter follows, that the passive fluid flow rate through the pump 10 may be adjusted to match the flow rate of coolant within the coolant garment 90 that is required for maximum metabolic heat production by the suit inhabitant. The pump 10 of the present invention may be adjusted to automatically match the required coolant flow rate over the complete range of metabolic heat production because of the fact that oxygen consumption of the suit inhabitant is essentially a linear function of metabolic heat. Thus, as more oxygen is required by the suit inhabitant due to increased exercise, a proportionately greater amount of fluid coolant is pumped through the coolant garment 90 by the pump 10 of the invention.

FIG. 2 shows a cross-sectional view of the self-contained fluid pump 10 illustrated in FIG. 1, which utilizes the novel structures of the invention to obviate the need for auxiliary motors and pumps for pumping one fluid by means of another fluid. Basically, the pump 10 shown in FIG. 2 includes an outer casing 12 sealed at one end by an inlet plug 15 having the inlet pipe 14 threaded therethrough. The other end of the casing 12 is sealed by an outlet plug 17 through which is threaded the=outlet pipe 16. Within the casing 12 is positioned an expandable tubular membrane 18. The tubular membrane 18 is connected, on one end, to the inlet pipe 14 by means of a clamp 21 and, on the other end, to the outlet pipe 16 by means ofa clamp 23. So that a pumping fluid may be injected into the void between the tubular membrane 18 and the internal surface of the casing 12, the inlet pipe 24 is threaded through the wall of the casing 12 near the inlet plug 15. The exhaust or outlet pipe 26 is threaded through the casing 12 near the outlet plug 17 to provide a means for exhausting the pumping fluid from the casing 12.

Before continuing with a discussion of the operation of the pump 10 ofthe present invention, it is important to notice that the casing 12 of the pump is cylindrical in shape in the preferred embodiment which is described. Moreover, the internal diameter of the cylindrical casing 12 is not constant, but rather the casing 12 has a first internal diameter over an internal surface 28 that extends from the inlet end of the casing 12 almost the entire length of the casing toward the outlet end. At the outlet end, the cylindrical casing 12 has a second diameter greater than the first diameter and extending over an internal cylindrical surface 27. A step 25 is formed where the surface 27 meets the surface 28. One may clearly understand, from the discussion which hereinafter follows, that the step 25 and the tubular membrane 18 cooperate to form an effective fluid seal. This fluid seal prevents the pumping fluid from prematurely exiting through the exhaust pipe 26 as the pumping fluid is injected into the void between the membrane 18 and the internal surface 28 of the casing 12. Certain advantages that will become clear from the discussion which follows accrue because of the inclusion of this internal valve structure. The most important of these advantages is the elimination of external control valves and auxiliary motors and pumps heretofore necessary for producing cyclic pressure fluctuations to collapse a membrane similar to the membrane 18 within the casing 12.

As shown in FIG. 2, when a passive fluid is to be pumped by the pump of the invention, the passive fluid flows from the fluid conduit 29 through the check valve into the inlet pipe 14 of the pump 10. The check valve 20 is shown to be a balltype which prevents reverse flow of passive fluid when a pumping fluid under pressure is forced into the casing 12 to collapse the tubular membrane 18. To the outlet pipe 16 is connected a similar ball-type check valve for determining a direction of flow of the passive fluid from the outlet pipe 16 through the check valve 30 to the fluid conduit 31.

It will be recognized by those skilled in the art that the pump 10 of the present invention is a peristaltic device; that is, the passive fluid is moved by compressing the flexible tubular membrane 18 which contains the passive fluid. In the embodiment described, it will be assumed hereinafter that the pumping fluid comprises a gas (such as oxygen) under pressure. Power to operate the pump 10 is derived from the expansion of the compressed gas, the flexible tubular membrane 18 serving as a barrier between the gas and the passive fluid contained within the membrane. Compression of the tubular membrane 18, due to the gas pressure applied to the inlet pipe 24, forces the passive fluid to exit the pump 10 through the outlet pipe 16, the direction of flow being determined by the

check valves

20 and 30.

As mentioned above, the tubular membrane 18 also serves the function of intermittently valving gas flow from the inlet pipe 24 to the exhaust pipe 26. This may be recognized by examining the sequence of operations within the pump 10. Assume initially that the tubular membrane 18 is filled with a passive fluid that is a liquid (such as water), and thus inflated to its maximum dimension as shown in FIG. 2. The maximum dimension of the membrane 18 obviously is determined by the internal wall 28 of the casing 12. An effective gas seal is formed by the membrane 18 and the edge of the step 25 in the casing 12, and gas flow into the pump 10 is trapped causing the gas pressure to increase in the volume between the membrane 18 and the casing 12. The gas pressure increases until its value exceeds that of the liquid pressure, at which time, the tubular membrane 18 begins to collapse at the inlet end of the pump. This condition is illustrated in FIG. 3.

Compression of the membrane 18 continues in a smooth motion from the inlet end of the pump 10 to the outlet end, thereby pumping the liquid therein contained out of the casing 12 through the outlet pipe 16. The gas seal is finally broken, as

, shown in FIG. 4, allowing the gas contained between the membrane 18 and the surface 28 to escape through the exhaust pipe 26. The sudden drop in gas pressure within the pump 10, as the gas escapes through pipe 26, opens check valve 20 and allows liquid to enter the membrane 18 through the inlet pipe 14. As liquid enters, the membrane 18 is forced to re-expand. During this operation of filling the membrane 18, a longitudinal force is exerted on the membrane 18 by the liquid, thereby holding open the internal gas valve until the membrane 18 has again filled with liquid. More particularly, the tubular membrane 18 is maintained in a relatively taut condition near the step 25 within the casing 12 until sufficient fluid is contained within the membrane 18 to cause the membrane to contact the

internal surfaces

27 and 28 of the casing 12. With the membrane 18 inflated so as to be forced against the step 25, the pumping action is ready to be repeated.

An extra benefit to those who may use the invention may be derived from the pump 10. It should be noted that the work done by the pumping fluid in pumping a passive fluid through the membrane 18 results in a temperature drop in the pumping fluid from the inlet pipe 24 to the outlet pipe 26. Thus, the exhausted pumping fluid is delivered to the space suit 50, illustrated in FIG. 1, at a slightly lower temperature than would otherwise be achieved. This is advantageous, since the cooler respiratory gas will cooperate with the coolant being pumped through the coolant garment to keep the suit inhabitant at a lower ambient temperature.

The pump 10 of the invention may be constructed of various materials, well known to those skilled in the art, depending upon the use to be made of the pump. If noncorrosive liquids, such as water and the like, are to be pumped through the membrane 18, the membrane 18 may be constructed of rubber or plastic material. The casing 12, in such an event, could be constructed of a Lucite material, fabricating the inlet plug 15 and the outlet plug 17 from rubber, plastic, or a metal (such as copper).

In accordance with the present invention, it has been found that a change in the internal dimensions of casing 12 (to form step 25) need be only a quarter of an inch or less. Some of the other dimensions, for example, of the embodiment of fluid pump described are: an overall length of approximately 4 inches; an internal surface 27 of approximately one inch in length; an external diameter of 0.75 inches; and a weight of 0.16 pounds. In practice it has been found that a pump of the present invention, fitting the foregoing description, is capable of a pumping speed of 30 cubic centimeters of fluid per second or better into a static pressure head of five pounds per square inch, for example, over a temperature range primarily limited by the temperature characteristics of the passive and pumping fluids. Thus, it has been found that the utilization of the basic concepts herein set forth provide a fluid pump which is capable of operating, independent of any auxiliary valves, pumps and motors, over temperature ranges greatly exceeding those heretofore achieved by the prior art fluid pumps.

Whereas a pumping system has been described, with reference to FIG. 1, employing but one of the fluid pumps of the present invention, a number of fluid pumps of the invention may be connected in parallel or in series to provide a pumping system of even greater efficiency. For example, a pumping system is shown in FIG. 5 which obtains approximately twice the pumping efficiency of the one illustrated in FIG. 1 by connecting in parallel two of the fluid pumps 10 and 10 of the invention. The fluid conduit 29 from the pressure reservoir 40 is coupled to the inlet pipe 14 of the pump 10 through a pipe T-coupling and the check valve 20. Similarly, the fluid conduit 29 is coupled to the inlet pipe 14' of the pump 10' through the coupling 105 and the check valve 20'. The passive fluid is expelled from the pump 10 through the outlet pipe 16, the check valve 30 and a T-coupling 107 to the fluid conduit 31, which is connected to the space suit 50. In like manner, passive fluid is expelled from the pump 10 through the outlet pipe 16, the check valve 30' and the T- coupling 107 to the fluid conduit 31.

With reference to the means of supplying pumping fluid to the

pumps

10 and 10 connected in parallel, it may be noticed that the pumping fluid is alternately applied to the pumps 10 and 10' by passing the pumping fluid from the bottle 60 through a diverter 120, interposed in the system between the bottle 60 and the inlet pipes 24 and 24' of the pumps 10 and 10', respectively. The diverter is shown to include a small chamber 121 into which the inlet pipes 24 and 24' protrude. Between the ends of the inlet pipes 24 and 24' there is positioned a flapper valve 124 connected to the side of the casing 121. The gas bottle 60 is connected to the diverter 120 by a coupling 122 secured to one side of the chamber 121.

The gas, or pumping fluid flow to drive the pumps 10 and 10' is fed through the diverter 120 before it is allowed to reach the pumps. Essentially, gas flow through the diverter 120 remains constant, the function of the diverter 120 being to alternately direct the gas flow to one pump at a time. The pump to which the pumping fluid flow is directed undergoes compression, while the other pump is filling with passive fluid.

The diverter 120 illustrated in FIG. 5 is a simply constructed device that is self-actuating. The flexible flapper 124 is situated between the two exit ports of the diverter and positions itself to seal one or the other of the two exit ports, depending upon whether a pressure P1 in the inlet pipe 24 is greater or less than a pressure P2 in the inlet pipe 24'. Assume that gas is flowing from the bottle 60 to the pump 10. In this instance, the gas pressure P1 in the inlet pipe 24 is greater than the pressure P2 in the inlet pipe 24' connected to the pump 10'. Thus, a gas pressure P3 within the diverter 120 .reflects this difference between the pressures P1 and P2 and forces the flapper 124 against the opening of the inlet pipe 24', thereby preventing gas flow to the pump 10. While the pumping fluid is not being applied to the pump 10', the tubular membrane 18' (not shown in FIG. 5) is filling with the passive fluid. When the fluid seal (which prevents the pumping fluid, or gas from prematurely exiting the exhaust pipe 26 of the pump is broken, the pressure P1 in the inlet pipe 24 decreases rapidly, thereby reducing the pressure P3 in the diverter 120 to a value less than the pressure P2 in the inlet pipe 24'. The flapper 124 is, therefore, released from the opening of the inlet pipe 24'. In response to the increase in gas flow to the inlet pipe 24 of the pump 10 when the gas seal breaks, the flapper 124 is moved against the opening of that inlet pipe 24, allowing the flow of pumping fluid to be diverted to the pump 10'.

From the foregoing it will be understood by those skilled in the art that, when pump 10 is pumping the passive fluid from the reservoir 40 to the space suit 50, the pump 10' is filling with liquid; and, when the pump 10' is moving the passive fluid from the reservoir 40 to the space suit 50, the pump 10 is filling with passive fluid. The efficiency is doubled because useful work is being accomplished by the pumping system during each of the filling intervals of the two parallel-connected pumps. I

Reference is made to FIG. 5a where there is shown an auxiliary view of an alternate embodiment of fluid diverter 120 that employs a ball 124 interposed between the

inlet pipes

24 and 24 for directing the gas flow to one or the other of the two

pumps

10 and 10. Since the movement of the ball 124' is similar to the movement of the flapper 124 shown in FIG. 5, further description of the diverter 120 shown in FIG. 5a is deemed to be unnecessary.

Attention is directed now to FIG. 6, wherein a pumping system is illustrated, for example, which also obtains approximately twice the pumping efficiency of the one illustrated in FIG. 1. However, in contrast to the pumping system of FIG. 5, the fluid pumps 10 and 10 of FIG. 6 are shown to be connected in series. Whereas a parallel connection of the two pumps 10 and 10' (as illustrated in FIG. 5) requires the use of four

check valves

20, 20, 30, and 30, a serially-connected arrangement, (as shown in FIG. 6) requires only three

check valves

20, 30 and 30. Similar to the diverter 120 shown in FIG. 5, the diverter 120 shown in FIG. 6 controls the flow of pumping fluid from the bottle 60 to one or the other of the pumps ID or 10. The operation of the diverter 120 in the series arrangement of the fluid pumps of the present invention is identical to the operation described above with reference to the parallel arrangement of the pumps. Therefore, a duplication of that explanation will not be made with reference to the pumping system in FIG. 6. It should be realized, however, that with either of the two arrangements of dual pump systems, illustrated in FIGS. 5 and 6, an inherent advantage accrues to the user by virtue of the fact that the system is designed to allow one pump to fail without the complete pumping system failing. Thus, not only is the efficiency of the pumping system increased, but also the reliability ofthe system is enhanced.

While the fluid pump of the invention has been described with reference to only one particular embodiment, it will be understood that various modifications could be made in the construction thereof without departing from the spirit and scope of the invention. Thus, by way of example and not of limitation, one skilled in the art might readily transpose the two fluids within the pump, that is, pass the pumping fluid through the center of the flexible tubular membrane 18 and the passive fluid between the flexible membrane 18 and the internal surface 28 of the casing 12. Additionally, the casing 12 may be constructed to be conical in shape having the inlet port for the passive fluid at the larger end of the cone, while the outlet port would be positioned at the tip, or smaller end of the cone. Essentially, the casing 12 may be of any shape which allows the flexible membrane 18 to block the escape of the pumping fluid through the exhaust pipe 26 when the membrane 18 is fully distended.

It is also noted that the pump 10 or pair of pumps, together with a coolant fluid reservoir and oxygen supply, may be included in a compact pack that can be carried on the back of the space suit; similarly, these components may be included as a unit in a space vehicle as part of the life-support system. Accordingly, it is to be expressly understood that the foregoing description shall be interpreted only as illustrative of the invention and that various changes may be made without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. A fluid pump comprising:

a cylinder having a first internal diameter and a second internal diameter meeting at an annular step near a first end of said cylinder;

means having an inlet port therein for closing a second end of said cylinder;

means having an outlet port therein for closing said first end of said cylinder;

first injection means for injecting a fluid to be pumped into said inlet port;

- an expandable tubular membrane positioned within said cylinder and connected between said inlet and said outlet ports, said tubular membrane and said annular step creating a fluid seal when said membrane is inflated to its maximum dimension with the fluid to be pumped;

second injection means for injecting a pumping fluid into the void between said tubular membrane and the internal surface of said cylinder to expel the fluid to be pumped, said injection means being located near said second end of said cylinder; and

exhaust means for venting said pumping fluid from the void when said fluid seal is broken, said exhaust means being located at the opposite end of said cylinder from said injection means.

2. A fluid pump as defined in claim 1 wherein said means for closing said first and second ends of said cylinder include fluid check valves.

3. A fluid pump as defined in claim 1 wherein said second injection means is connected to said cylinder near said second end and said exhaust means is connected to said cylinder near said first end.

4. A fluid pump as defined in claim 3 wherein said first internal diameter begins at said second end of said cylinder and extends inward to said annular step, said first internal diameter of said cylinder being greater than said second internal diameter.

5. A fluid pump for moving a first fluid by successively compressing a flexible tube containing the first fluid by means of a second fluid having a greater pressure than said first fluid, said pump comprising:

an elongated casing having a greater internal dimension at one end thereof than at an opposite end;

inlet means for injecting the first fluid into one end of said casing;

outlet means for withdrawing the first fluid from the opposite end of said casing from said inlet means;

an expandable tube positioned within said casing and interconnecting said inlet means and said outlet means for conveying the first fluid from said inlet means to said outlet means, said tube being substantially entirely contiguous with the internal surface of said casing, and forming a fluid seal between said tube and the internal surface of said casing when said tube is filled with the first fluid;

injection means for inserting the second fluid at a substantially constant pressure between said tube and the internal surface of said casing to force the first fluid from said tube, said injection means being coupled to said casing near said inlet means; and

exhaust means for venting the second fluid from a void between said tube and the internal surface of said casing as said tube fills with the first fluid, said void being formed as the first fluid is forced from said tube, said exhaust means being attached to said casing near said outlet means and cooperative with said tube to control the escape of the second fluid.

6. A fluid pump as defined in claim wherein said elongated casing is cylindrical in shape.

7. A fluid pump as defined in claim 6 wherein the change in the internal dimension of said casing from one end to the other is formed by two cylindrical surfaces, a first cylindrical surface of substantially constant diameter beginning at the end of said casing adjoining said inlet means and extending a first length toward the end of said casing adjoining said outlet means, a second cylindrical surface of substantially constant diameter joining said first cylindrical surface intermediate said inlet and outlet means and extending a second length to the end adjoining said outlet means, said joint between said first and second cylindrical surfaces forming an annular step that functions with said tube to intermittently valve the flow of the second fluid through said exhaust means.

8. A fluid pump as defined in claim 7 wherein the first fluid comprises a liquid and the second fluid comprises a gas.

9. A fluid pump as defined in claim 8 wherein a relatively constant gas pressure source is coupled to said injection means to supply said gas.

10. A fluid pump as defined in claim 9 wherein said inlet means and said outlet means each include a check valve for establishing unidirectional flow of said liquid through the pump from said inlet means out through said outlet means.

11. A fluid pump as defined in claim 7 wherein said first length is greater than said second length.

12. A fluid pumping system for moving a first fluid by successively compressing and relaxing, by means of a second fluid, a tubular membrane containing the first fluid, said pumping system comprising:

an elongated casing having a greater internal dimension at one-end thereof than at an opposite end;

a first source of the first fluid;

inlet means interconnecting said first fluid source and one end of said casing for injecting the first fluid into said casa utilization device for the first fluid;

outlet means for discharging the first fluid from said casing, said outlet means interconnecting said utilization device and an end of said casing opposite said inlet means;

an expandable tubular membrane positioned within said casing and interconnecting said inlet means and said outlet means for conveying the first fluid therebetween, said tubular membrane being substantially entirely contiguous with the internal surface of said casing when said mem- -brane is filled with the first fluid; a second source of the second fluid, the second fluid being discharged therefrom at a substantially constant pressure; injection means for inserting the second fluid at substantially constant pressure between said tubular membrane and the internal surface of said casing to force the first fluid from said membrane, said injection means intercoupling said second fluid source and said casing at a location near said inlet means; and

exhaust means for discharging the second fluid from a void between said tubular membrane and the internal surface of said casing, said exhaust means being attached to said casing near said outlet means and cooperative with said tubular membrane to control the escape of the second fluid.

13. A thermal control system comprising:

a space suit including an inner chamber and a coolant garment;

a reservoir for storing a first fluid;

a source of a second fluid, said source including a regulator for discharging said second fluid at a substantially constant pressure;

a fluid pump for moving said first fluid by successively compressing and relaxing, by means of said second fluid, a tubular membrane containing said first fluid, said pump including a casing, inlet means interconnecting said reservoir and one end of said casing for injecting said first fluid into said casing, outlet means for discharging said first fluid from said casing, said outlet means interconnecting said coolant garment and an end of said casing opposite said inlet means, an expandable tube positioned within said casing and interconnecting said inlet means and said outlet means for conveying the first fluid from said inlet means to said outlet means, said tube being contiguous with the internal surface of said casing when said tube is filled with said first fluid, injection means for inserting said second fluid at a substantially constant pressure between said tube and the internal surface of said casing to force said first fluid from said tube, said injection means intercoupling said source of said second fluid and said casing near said inlet means, and exhaust means for venting the second fluid from a void between said tube and the internal surface of said casing as said tube fills with the first fluid, said void being formed as the first fluid is forced from said tube, said exhaust means intercoupling the inner chamber of said space suit and said casing near said outlet means and being cooperative with said tube to control the escape of said second fluid.

14. A thermal control system comprising:

a space suit including an inner chamber and a coolant garment;

a reservoir for storing a first fluid therein, said reservoir being coupled to said coolant garment for receiving said first fluid therefrom;

a source of a second fluid, said source including a regulator for discharging said second fluid at a substantially constant pressure; and

a fluid pump for moving said first fluid through said coolant garment in response to the requirement of said second fluid in said inner chamber, said fluid pump including a first fluid chamber having inlet and outlet ports therein, said inlet port being coupled to said reservoir and said outlet port being coupled to said coolant garment, a second fluid chamber interposed in the system between said source of a second fluid and said inner chamber of said space suit, said fluid pump having a flexible wall separating said first chamber from said second chamber,

said flexible wall preventing said second fluid from entering said inner chamber of said space suit.

15. A thermal control system comprising:

a space suit;

a reservoir for storing a first coolant fluid, said first fluid being connected to said space suit;

pumping means including a flexible membrane coupling said reservoir and said source of second fluid to said space suit and being powered by the second fluid for moving the first fluid from said reservoir to said space suit, said first fluid and said second fluid being isolated from each other in said pumping means said flexible membrane.

16. A pumping system for moving a first fluid by successively compressing and relaxing, by means of a second fluid, a tubular membrane containing the first fluid, said pumping system comprising:

a utilization device for the first and the second fluids;

a reservoir for storing the first fluid;

a source of second fluid, said source including a regulator for discharging said second fluid at a substantially constant pressure;

a pair of fluid pumps interposed between said reservoir and said utilization device, each of said fluid pumps being adapted to move the first fluid by successively compressing and relaxing, by means of the second fluid, a tubular membrane containing the first fluid, each of said pumps including a casing, inlet means intercoupling said reservoir and one end of said casing for injecting the first fluid into said casing, outlet means for discharging the first fluid from said casing, said outlet means interconnecting said utilization device and an end of said casing opposite said inlet means, an expandable tube positioned within said casing and interconnecting said inlet means and said outlet means for conveying the first fluid from said inlet means to said outlet means, said tube being contiguous with the internal surface of said casing when said tube is filled with the first fluid, injection means for inserting the second fluid, at a substantially constant pressure, between said tube and the internal surface of said casing to force the first fluid from said tube, and exhaust means for venting the second fluid from a void between said tube and the internal surface of said casing as said tube fills with the first fluid, said void being formed as the first fluid is forced from said tube, said exhaust means intercoupling said utilization device and said casing near said outlet means and being cooperative with said tube to control the escape ofthe second fluid; and

a diverter intercoupling said source of the second fluid and said inlet means of each fluid pump, said diverter including a casing, said injection means of each pump being coupled to said casing on opposite sides thereof, valve means interposed between the openings of said injection means within said diverter casing for alternately directing the flow of the second fluid to one or the other of said injection means.

17. in a life support system for a space enclosure having at least two separate fluid utilization systems:

a source of compressed gas;

a source of coolant fluid;

means for pumping said compressed gas and said coolant fluid; and

means for releasing the compressed gas and said coolant fluid into separate fluid utilization systems of said space enclosure and for simultaneously powering said pumping means, whereby the temperature drop which would normally accompany release of the compressed gas is reduced toward the desired ambient temperature of the enclosure.

18. A thermal control system comprising:

a space suit including an inner chamber and a coolant garment;

a reservoir for storing a first fluid;

a fluid pumping system for moving said first fluid by successively compressing and relaxing, by means of said second fluid, a tubular membrane containing said first fluid, said pumping system including an elongated casing having a greater internal dimension at one end thereof than at an opposite end, inlet means interconnecting said reservoir and one end of said casing for injecting said first fluid into said casing, outlet means for discharging said first fluid from said casing, said outlet means interconnecting said coolant garment of said space suit and an end of said casing opposite said inlet means, an expandable tubular membrane positioned within said casing and interconnecting said inlet means and said outlet means for conveying said first fluid therebetween, said tubular membrane being contiguous with the internal surface of said casing when said membrane is filled with said first fluid, injection means for inserting said second fluid between said tubular membrane and the internal surface of said casing to force said first fluid from said membrane, said in ection means mtercouplmg said second fluid source and said casing at a location near said inlet means, and exhaust means for discharging said second fluid from a void between said tubular membrane and the internal surface of said casing, said exhaust means interconnecting said casing near said outlet means and said inner chamber of said space suit and being cooperative with said tubular membrane to control the escape of said second fluid to said inner chamber.