US3436914A

US3436914A - Hydrostatic energy accumulator

Info

Publication number: US3436914A
Application number: US643311A
Authority: US
Inventors: Andre M Rosfelder
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1967-05-29
Filing date: 1967-05-29
Publication date: 1969-04-08
Anticipated expiration: 1986-04-08

Description

April 1969 A. M. ROSFELDER 3,436,914

HYDROSTATIC ENERGY ACCUMULATOR Filed May 29, 1967 Sheet of 2 32 16 n 26 F l G, I. ////////////X( F I G. 2

I I Q 496 FI G. 3.

7 2 6 8 l N VEN TOR FIG. 4. ANDRE-M. ROSFELDER JOSEPH H. GOLANT ATTORNEY.

April 8, 1969 A. M. ROSFELDER 3,436,914

HYDROSTATIC ENERGY ACCUMULATOR Filed May 29, 1967 Sheet 2 me 128 ,pg

F I G. 6. Q

F I G. 8 PC I86} JV V V V V INVENTOR.

ANDRE M. ROSFELDER I82 BY PH JOSEPH H. GOLANT ATTORNEY.

atent O1 fice 3,436,914 Patented Apr. 8, 1969 3,436,914 HYDROSTATIC ENERGY ACCUMULATOR Andre M. Rosfelder, La Jolla, Calif., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed May 29, 1967, Ser. No. 643,311 Int. Cl. F15b 1/02, 13/02, 21/04 US. CI. 6051 9 Claims ABSTRACT OF THE DISCLOSURE The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to energy accumulators and more particularly to hydrostatic energy accumulators for undersea environments.

Description of the prior art It is well known in the art to send to a preselected depth in the ocean a cylinder having its interior at a pressure of about one atmosphere and having a locked piston within the cylinder; the piston is then released to accomplish work because of the hydrostatic pressure differential across the piston. In 1939 Varney et al., Patent No. 2,176,477, illustrated the use of the hydrostatic principle to force a core barrel into the ocean bottom; in 1965 Bouyoucos, Patent No. 3,163,985, illustrated the use of the hydrostatic principle in a hydraulic energy storage system. While the physics principles involved in using the energy source available beneath the ocean are well known, in practice many of the devices built to date have failed to perform as desired. This has generally been due to a lack of control of the apparatus once it has reached the desired depth. The tremendous pressure difierential created across the piston would cause the piston to move quite quickly and slam against the cylinder bottom and once the piston was released all the energy accumulated would be expended quickly; there would be no way to purposely vary the rate of work done or to even provide that the work be done at a constant rate. The abovementioned drawbacks have made the practical application of the hydrostatic principle rather limited especially in the field of coring and underwater sampling.

SUMMARY OF THE INVENTION comprising in combination a chamber, means connected to the chamber for receiving a fluid, a movable chamber partition for dividing the chamber into a first portion and a second portion, the first portion being connected to the means for receiving a fluid, an orifice means connected to the chamber for controlling the fluid received, a valve means connected to the chamber for controlling the fluid received and a load means connected to the chamber for receiving the energy that has been accumulated, the load means being adapted to be of a rotary nature or of a translational nature enabling the accumulator to be combined with a great many devices so as to otter an adaptable short term energy source. In variations of my invention, amplification of the pressure ditferential may be accomplished as well as providing thin walled cylinders to operate with an internal pressure substantially equal to the external pressure so as to alleviate sealing problems.

An object of the invention is to provide a hydrostatic energy accumulator for undersea use that is smooth acting and adapted to be controllable for varying the application of the energy to the load as well as adapted to be stopped and started at desired intervals along a work cycle.

Another object of the invention is to provide a hydrostatic energy accumulator which is adapted to amplify the efiect of the energy accumulated.

Still another object of the invention is to provide a hydrostatic energy accumulator which alleviates the usually very difiicult sealing problems which occur during the use of deep ocean instrumentation.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic partial sectional view of a hydrostatic energy accumulator embodiment.

FIG. 2 is a diagrammatic partial sectional view of another embodiment of my invention.

FIG. 3 is a diagrammatic view of the FIG. 2 embodiment in a multiple arrangement.

FIG. 4 is a diagrammatic partial sectional view of still another embodiment of my invention illustrating an amplification of the energy accumulated.

FIG. 5 is a diagrammatic sectional view of a still further embodiment of the invention.

FIG. 6 is a diagrammatic view of the FIG. 5 embodiment in a multiple arrangement.

FIG. 7 is a diagrammatic partial sectional view of yet another embodiment of my invention.

FIG. 8 is a diagrammatic view of a valve means.

FIG. 9 is a partial diagrammatic sectional view of a sealing arrangement for the FIG. 4 embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings wherein like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a chamber such as a hollow cylinder 10 which for reference purpose may have an upstream end 12 and a downstream end 13. Within the cylinder 10 is a movable chamber partition which may be a piston head 14 adapted to slide along the length of the cylinder. The piston head 14 divides the cylinder 10 into two portions, a first portion 16 upstream of the piston head and a second portion 17 downstream of the piston head.

Connected to the upstream end 12 of the cylinder 10 is a means for receiving a fluid which means may be a conduit 18 opening to the surrounding sea. The first portion 16 communicates with the conduit 18. Also connected to the cylinder 10 and preferably disposed Within the conduit 18 are a valve means 19 and a constriction means 20".

The purpose of the valve means 19 and constriction means 20 is to control the rate of fluid received into the first portion 16 of the cylinder 10. The valve means 19 may be one of the many valves commercially available which are adapted to regulate a fluid flow to effect a desired result. A valve which will prevent the slamming of the piston head 14 upon downstream end 13 is illustrated in FIG. 8 and will be described below. The constriction means may also be designed to achieve a desired result and may be of the variable type. The combination of the valve means 19 and the constriction means 20 with the hydrostatic accumulator achieves one of the major advantages of the FIG. 1 embodiment in that a control is built into the accumulator to prevent rough or sporadic movement of the piston head 14; this control allows the accumulated energy to be used in a predetermined sequence and at a definite rate.

Connected to the chamber and preferably directly to the piston head 14 is a load means 22 (which is depicted with a broken line in FIG. 1, but which is understood to be any one of a great variety of oceanographic equipment for which the accumulator may be used as an energy source). For example, if the load means is a coring barrel then a rigid piston arm 24 may be needed to connect the piston head 14 to the coring barrel to enable the necessary driving force to be applied to the barrel.

During descent the second portion 17 of the cylinder is to remain at a relatively low pressure such as atmospheric pressure, while the ambient pressure of the ocean builds up rapidly to a relatively high pressure. To ensure the pressure integrity of the second portion 17, seals such as seal 25 placed about the piston head 14 and seal 26 placed in the downstream end 13 of the cylinder may be provided.

In operation the valve means is selectively opened at a predetermined depth causing a pressure differential to appear across the piston head 14; that is, a high pressure will appear on an upstream face 28 of the piston head while a relatively low pressure appears at a downstream face 30. This pressure differential will cause the piston head to slide in a downstream direction toward the downstream end 13 of the cylinder. At the same time the driving force is transmitted from the piston head through the piston arm 24 to the load means 22, which, if a core barrel, will cause the core barrel to be driven into the ocean bottom. Again it is noted that the combination of the valve means 19 and the constriction means provide a control by selectively metering the rate of flow of the incoming fluid so as to selectively receive the tremendous pressure which is available at the predetermined depth and to selectively transmit that pressure to the upstream face 28 of the piston head 14. This allows for a smooth movement of the piston head 14 or if desired an intermittent movement of the piston head since by closing the valve means 19 the piston head will come to rest. As the piston head 14 moves downstream in the cylinder 10 the volume of the second portion 17 decreases while the pressure increases until the fluid within that portion reaches a pressure substantially equal to the ambient ocean pressure so that a pressure differential across the piston head no longer exists. At this time the accumulated energy will have been expended and the piston head will come to rest. Practically speaking, this will occur when the piston head is very near the downstream end 13 so that eflectively the piston will travel the entire length of the cylinder 10 from the upstream end 12 to the downstream end 13.

Upon ascent the accumulator may again be used to perform useful work. [f the valve means 19 remains open the ambient ocean pressure will decrease upon ascent causing a reverse pressure differential across the piston head 14; that is, a higher pressure will appear upon the downstream face 30 and a lower pressure upon the upstream face 28. This pressure differential will cause the piston head to move away from the downstream end 13 and toward the upstream end 12, expanding the volume of the second portion 17. If the load means 22 is a core barrel, the reverse movement may be used to cause the core barrel to be retracted, thus possibly protecting the core sample it such is found to be desirable. However, if the reversing movement of the piston head 14 is undesirable then the valve means 19 may be closed and a second valve means may be provided so that as ascent occurs the high pressure built up in the second portion 17 will be released through a passageway 33 and past the valve means, which may be comprised of a ball 34 confined by any suitably known means, to the ambient sea. It is noted that the ball valve 34 will open only when the pressure in the passageway 33 is higher than the pressure in the surrounding sea.

It is noted that in the FIG. 1 embodiment the walls of cylinder 1-0 may be thick walled to withstand the pressure to be experienced at its operating depth.

The FIG. 2 embodiment operates in a similar manner to the embodiment just described in FIG. 1. The FIG. 2 embodiment also has a chamber and movable chamber partition which may be a cylinder 40 having an upstream end 41 and a downstream end 42 for reference and a piston head 43, respectively. There is also a valve means 44 and constriction means 46 connected to the cylinder as well as a means connected to the chamber for receiving a fluid such as a conduit 47. As in the FIG. 1 embodiment, a load means designated as 49 may be connected to the cylinder and preferably to a piston arm 50 which is connected to the piston head 43 so as to directly transmit the accumulated energy from the piston head 43 to the load means 49. In addition, the FIG. 2 embodiment has several other elements: a second chamber 52 and a means such as a conduit 51 for communicating the second chamber 52 to the cylinder 40. The chamber '52 will be maintained at a relatively low pressure, such as atmospheric pressure, during the initial portion of the systems operation and may be equal to the volume of cylinder 40.

In the FIG. 2 embodiment the cylinder 40 will be thin walled and the chamber 52 will be thick walled. My use of the terms thick and thin is to indicate that the walls of the chamber 52 are of sufiicient thickness to avoid substantial deflection at its designed operating depth whereas the walls of the thin walled cylinder 40 are designed to be flexible and uniformly compressed by the ambient sea pressure.

As in the FIG. 1 embodiment, the piston head 43 divides the cylinder 40 into a first portion 53 situated between the upstream end 41 of the cylinder and an upstream face 54 of the piston head and a second portion 55 which is located between a downstream face 56 of the piston head and the downstream end 42 of the cylinder. Within the second portion 55 may be a non-corrosive fluid which is adapted to be received by the second chamber 52 through the conduit 51. P

For operation it is desirable to have the compressibility of the fluid in the second portion 55, the compressibility of the cylinder 40, and the compressibility of the piston head 43 substantially equal. These conditions are fulfilled by using components of matching compressibilities, for most hydraulic fluids such as light oils, glycerine, etc., these conditions are fulfilled by most plastic materials and various metals or alloys such as cast iron, magnesium alloys, aluminum alloys, copper alloys, etc. Therefore, at operating depth the pressure of the system and within the system, except for the chamber 52, will be substantially equal to the surrounding sea pressure. This equalization prevents sealing problems which are a great nuisance presently. Only the valve means 44 and chamber 52 will have to withstand a pressure differential. A seal 58 around the piston head 43 may be used to keep the fluid in the first portion 53 from mixing with the fluid in the second portion 55. When valve means 44 is selectively opened a pressure differential is created across the piston head 43 causing a higher pressure on the upstream face 54, and a lower pressure on the downstream face 56 which will cause the piston head to move from the upstream end 41 of the cylinder to the downstream end 42. In this process the fluid located in the second portion 55 is received by the second chamber 52 through the conduit 51. If the valve means 44 is located within the conduit 51 then the movement of the fluid may be controlled, while the constriction means 46 located in conduit 47 acts to control a fluid such as sea water entering into the first portion 53.

FIG. 3 illustrates the FIG. 2 embodiment in a multiple arrangement having one large low pressure second chamber 52a and several thin walled cylinders 40a, 40b and 40, each of which may be connected to a load means indicated respectively 49a, 49b and 49c.

Another embodiment of my invention is shown in FIG. 4. the common elements with my first two embodiments are a chamber cylinder 60, a movable chamber partition piston head 61, means for receiving a fluid, a conduit 62 connected to the cylinder 60, and a constriction means 63 and valve means 64 connected to the cylinder and preferably disposed within the conduit 62 for controlling the fluid received. The piston head 61 divides the cylinder 60 into a first portion 65 and a second portion 66, said second portion to be maintained at a relatively low pressure. A second chamber 68 is connected to the cylinder 60, the chamber 68 being thin walled while the cylinder 60 is thick walled. The chamber 68 contains a second movable partition which may be a piston head 70 for dividing the second chamber into a first portion 72 and a second portion 74. The piston head 70 is shown sectionally larger than the piston head 61 and there is means connecting the two piston heads such as arm 76 so that any force applied to the smaller piston head 61 is transmitted to the larger piston head 70. The larger piston head applies the force which is upon the piston head 61 over a greater area thereby acting as a flow amplifier.

The FIG. 4 embodiment has a load means 78 which differs from the FIG. 1 and FIG. 2 load means by being part of a hydraulic circuit comprising a lead conduit 80 and return conduit 82 and being depicted as a rotary turbine. It is to be understood that rotary motion or translational motion may be accomplished with any of the embodiments of my invention by simply making slight modifications of the several embodiments. A fluid may be located in the second portion 74 of the chamber 68 which may flow through the conduit 80, drive the load means 78 and then flow to the first portion 72 through the conduit 82. Circulating the fluid in the manner just described allows the accumulated energy to be received by the load means.

In operation, the valve means opened to allow sea water to enter the cylinder 60 thereby causing a pressure differential to be created across the piston head 61. The piston head 61 will move across the cylinder 60 from its upstream end 83 to its downstream end 84. This motion is transmitted directly to the second piston head 70 by the arm 76 so that the fluid within the second portion 74 of the chamber 68 is pushed into the conduit 80 past the load means 78 and returned to the first portion 72 by way of the conduit 82.

Here again, the advantages of the system are its ability to control the incoming fluid by means of the valve means 64 and the constriction means 63 thus ensuring smooth operation. In addition, by structuring the chamber 68 thin walled as well as by having the chamber 68, the piston head 70 and the fluid within the second portion 74 of equal compressibility, sealing problems may be reduced especially about the rotary turbine as rotary elements have always presented difficult sealing problems. Also the use of two sectionally diflerent pistons allows an amplification effect by having a larger quantity of fluid moved through the hydraulic circuit. It is to be understood that piston head 70 may be sectionally smaller than piston head 61 thereby creating a pressure amplifier system 64 may be selectively the first portion 65 of which may be useful in shallow water operation (as opposed to the flow amplifier, deep water system disclosed above).

It should be noted here that the valve means 64 may be located in any one of three locations: with the conduit 62 as depicted in FIG. 4, or within conduit 80, or if fluid fills the entire system, that is, fills the second portion 74, the conduit 80, and the conduit 82, then the valve means may be placed within the conduit 82.

If the valve means should be moved from its position as depicted in the FIG. 4 embodiment then a severe sealing problem may exist at the upstream end 83 of the cylinder 60 since the piston head 61 may be directly subjected to the ambient sea pressure. A solution to this problem is to make the piston head 61 of two sections, FIG. 9, a larger section 85 and a smaller section 86 with a corresponding annular notch 88 for the section 86 in the upstream end 83 of the cylinder 60.

Seals

90 and 92 are provided about

sections

86 and 85, respectively. A very tight fit would be provided between the small section 86 and the annular notch 88 to withstand the pres sure. However, by creating a tight fit, friction is increased also. But since the distance travelled by the small sections 86 within the notch 88 is short, the friction to be overcome is small. Meanwhile, a much looser fit may be made between the larger section 85 and the interior wall of the chamber 60 to substantially reduce sliding friction; it is likely that the cylinder 60 even though thick walled will be deflected inward slightly by the tremendous pressure under which the accumulator may be subjected. By providing for a loose fit and a flexible seal 92, sliding friction will not increase appreciably even with a deflection of the cylinder. Water leakage past the seal 92 will not become a serious problem because once the piston head starts to move it will do so relatively quickly. A problem, however, may arise if it is desired to stop the piston head before it has reached a downstream end 84 of the cylinder 60. The severity of the problem would depend upon the deflection of the walls of the cylinder 60, the greater the deflection the more effective is the seal and, therefore, the less water leakage. But under certain conditions it may be necessary to trade off the advantages gained by reducing friction to that gained by being able to operate the accumulator intermittently. A seal 93 may also be placed in the downstream end 84 to prevent leakage between second portion 66 and first portion 72.

The embodiment shown in FIG. 5 is similar to that shown in FIG. 4 and operates in an analogous manner. The embodiment comprises a first thin walled chamber 100, a second thin walled chamber 102 and a third thick walled chamber 104. A movable partition piston head 106 divides the chamber into two portions, a first portion 108 and a second portion 110. A second movable partition piston head 112 divides the chamber 102 into two portions, a first portion 114 and a second portion 116; an arm means 117 connects the two

movable partitions

106 and 112. Fluid is received into the first portion 108 of the first chamber 100 by a fluid receiving means such as a conduit 118 within which a constriction means 120 is disposed for control. A valve means 122 is connected to the chamber 100 to also control the fluid received. A hydraulic circuit comprising a lead conduit 124, a load means 126 and a return conduit 128 provide the means for achieving useful work from the accumulated energy. The second portion of the chamber 100 and the first portion 114 and second portion 116 of the chamber 102 as well as the

conduits

124 and 128 are adapted to contain a fluid which may be a non-corrocive hydraulic oil. By having the compressibility of the

chamber

100 and 102, the

movable partitions

106 and 112, and the fluid in the system substantially equal, the pressure of and within the system is substantially equal to the pressure outside the system thereby substantially reducing the sealing problems.

The only seals necessary may be a seal 130 about partition 106 which will prevent sea water in the first portion 108 from mixing with the hydraulic fluid in the second portion 110. Since the pressure in both portions is substantially equal, there will not be a critical sealing problem, a simple O-ring seal is sufficient. Another seal may be placed about partition 112 to prevent fluid from leaking around the partition because a slight pressure differential will be present during operation. Or, as is illustrated, an annular flexible element 131 may be used to divide the

portions

114 and 116, one end of the flexible element attached to the partition 112, the other end connected to the interior wall of chamber 102. The advantage of such an element 131 known in the art as a rolling diaphragm is that friction between the partition 112 and the chamber 102 is eliminated.

In operation, the valve 122 may be opened subjecting the partition 106 to a pressure differential causing the partition to be moved in a downstream direction. The fluid in the second portion 110 will flow through a conduit 129 into the relatively low pressure thick walled chamber 104 as the volume of second portion 110 decreases. In turn, the second movable partition 112 is moved forcing the fluid in the second portion 116 into the hydraulic circuit to the load means 126.

FIG. 6 depicts multiple use of the FIG. embodiment to illustrate operation of two load means 126a and 126b with one thick walled chamber 104a. It is to be noted that partition 112 may be sectionally larger (as shown) or smaller; thus the system may be a flow amplifier or a pressure amplifier.

The FIG. 7 embodiment illustrates a first thick walled chamber 140, a movable partition 142 dividing the chamber into a [first portion 144 and a second portion 146, a valve means 148 and a constriction means 150 connected to the chamber 140 for controlling the receipt of a fluid into the first portion 144 and a hydraulic circuit comprising a lead conduit 152, a load means 154 and a return conduit 156. A second thick walled chamber 160 is provided with a resilient partition 162 dividing the chamber 160 into a first portion 164 which has an opening to the lead conduit 152 and communicates with the fluid within the second portion 146, and a second portion 166 which is separated from the hydraulic circuit by the resilient partition 162. In this embodiment, the second portion 166 is held at a relatively low pressure until operation. To operate, valve 148 is selectively opened to allow the fluid within the second portion 146 to be circulated through the hydraulic circuit. The low pressure existing in the second portion 166 of the chamber 160 reduces the pressure on the downstream face 167 so as to create a pressure differential, the high pressure being created by forces acting upon an end 170 of a rod 172 which is connected to an upstream face 173 of partition 142. With the pressure differential across the partition 142 a portion of the fluid in the second portion 146 will be pushed into the lead conduit 152. After an amount of fluid has left the portion 146 the partition 167 will move an incremental distance. This incremental move will cause a momentary lower pressure at the upstream face 173 so that the fluid in the hydraulic circuit will flow from the conduit 152 through the load 154 to the conduit 156 and into the first portion 144. Now that a complete cycle has been achieved, a momentary low pressure again appears at the downstream face 167' because of the low pressure in the portion 166 and the partition will again move an incremental distance downstream forcing more fluid into the conduit 152 and causing the cycle to repeat itself once again. Chamber 160 need be large enough only to initiate movement of the piston once the valve 148 has triggered the system. The advantage of the system is that it may be made very compact.

FIG. 8 is an example of a valve means which may be used in my various embodiments. The valve comprises a casing 180, a valve seat 182, a valve plug 184, a valve stem 186 and a valve spring 188. P indicates the high ambient pressure of the sea which will cause the valve plug 184 to be pulled away from the valve seat 182 if that pressure is suflicient to overcome the combined pressures of P the low pressure within the system, plus P the control pressure of the valve spring 188. By calculating P may be made sufficient to close the valve when the piston is near the end of its cylinder, thus preventing slamming of the piston.

The constriction means used throughout the different embodiments may be of any commercial available design and may be of a variable type so as to add flexibility to my embodiments.

It is to be noted, of course, that in construction of my FIGS. 4, 5 and 6 embodiments the cylinder 60 and the chamber 68, FIG. 4, are of generally equal lengths as are the lengths of the

chambers

100 and 102, FIG. 5.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. An improved hydrostatic energy accumulator for high fluid pressure environments comprising in combination:

a chamber;

means connected to the chamber for receiving a said high pressure fluid environment;

a freely movable chamber partition for dividing the chamber into a first portion and a second portion;

conduit means communicating said first portion with said fluid environment;

a flow regulating valve disposed in said conduit means for normally excluding said environment and when opened for controlling the rate of flow through said conduit means into said first portion;

an orifice constriction means disposed in said conduit means between said valve and said first portion for controlling the rate of flow through said conduit means into said first portion; and

load means connected to said chamber for receiving the energy accumulated,

wherein said accumulator is adapted to be dropped or lowered into the sea, said valve means being closed until a specific depth is reached; said valve means being selectively opened to cause a pressure differential across the chamber partition so that energy may be made available for the load,

said second chamber portion having its interior cavity normally at about atmospheric pressure when said environment is so excluded.

2. An improved hydrostatic energy accumulator as claimed in claim 1 including:

a second valve means communicating the second portion with the sea environment.

3. An improved hydrostatic energy accumulator as claimed in claim 1 wherein:

the chamber is thin walled; and including a second chamber, said second chamber being thick walled; and means communicating the second chamber to the thin walled chamber.

4. An improved hydrostatic energy accumulator as claimed in claim 3 including:

a fluid in the second portion of said thin walled chamber wherein,

the compressibility of said fluid, said thin Walled chamber and said movable chamber partition are substantially equal; and said second chamber being adapted to receive the fluid from the second portion of the thin walled chamber 5 through the communicating means.

5. An improved hydrostatic energy accumulator as claimed in claim 1 wherein:

the chamber is thick walled; and including a second chamber being thin walled connected to the thick walled chamber and adapted to contain a fluid;

a second movable partition for dividing said second chamber into a first portion and a second portion;

a hydraulic circuit including the load means through which the fluid from the second portion of the second chamber can circulate to the first portion of the second chamber whereby the load receives the accumulated energy;

means connecting the first partition to the second partition; and

said second partition being sectionally different from the first partition of the thick walled chamber.

6. An improved hydrostatic energy accumulator as claimed in claim 5 including:

a fluid within the second chamber; and

the compressibility of said fluid, said second chamber, and said second movable partition are substantially equal.

7. An improved hydrostatic energy accumulator as claimed in claim 1 wherein:

the chamber is a first thin walled chamber;

said second portion is adapted to contain a fluid;

a second thin walled chamber connected to the first thin walled chamber and adapted to contain a fluid;

a third chamber being thick walled communicating with the first thin walled chamber, said thick walled chamber being adapted to selectively receive the fluid from the second portion of the first thin walled chamber;

a second movable partition for dividing said second thin walled chamber into a first portion and a second portion;

a hydraulic circuit including the load means through which the fluid from the second portion of the second thin walled chamber can circulate to the first portion of the second thin walled chamber whereby the load receives the accumulated energy;

means for connecting the partition of the first thin walled chamber to the second partition; and

said second partition being sectionally different from the partition of the first thin walled chamber.

8. An improved hydrostatic energy accumulator as claimed in claim 7 including:

a fluid within the second portion of the first thin Walled chamber and the first and second portions of the second thin walled chamber; and

the compressibility of said fluid, the first thin walled chamber, the second thin Walled chamber, the partition of the first thin walled chamber and the second partition are substantially equal.

9. An improved hydrostatic energy accumulator as claimed in claim 1 wherein:

said chamber is a first thick walled chamber and including said first and second portions adapted to contain a fluid;

a hydraulic circuit including the Work means through which the fluid from the second portion of the chamber can circulate to the first portion;

a second thick walled chamber having an opening to the hydraulic circuit; and

a resilient partition dividing said second chamber into a first portion and a second portion, said first portion communicating with the fluid in the first chamber.

References Cited UNITED STATES PATENTS 2,644,307 7/1953 Blair 57 3,163,985 1/1965 Bouyoucos 6051 3,205,969 9/ 1965 Clark 6051 XR 2,160,920 6/ 1939 Strawn.

EDGAR W. GEOGHEGAN, Primary Examiner.

US. Cl. X.R. 601; 6