Pressure compensation device designed for underwater applications

Abstract

A system filled with a fluid, designed for underwater applications, in which the interior of a housing and/or tank forms a fluid region which is sealed with respect to the surrounding seawater region, includes at least one hydraulic pressure compensation device, which at least raises the pressure level of the fluid region to the ambient pressure prevailing in the seawater region. The pressure compensation device is constructed in two stages in such a way that at least one store having a flexible wall region and at least one piston store having a displaceable piston are arranged in series. The use of the pressure compensation device to pressurize at least one housing filled with fluid for a hydraulic actuating shaft is also proposed.

Claims

1. A pressure compensation device designed for underwater applications and configured to seal a housing with respect to a surrounding seawater region, said housing forming a fluid region, the pressure compensation device comprising: at least one accumulator with a flexible wall region, the at least one accumulator defining a first interior space fluidly connected to the seawater region and a second interior space separated from the first interior space by the flexible wall region; and at least one piston accumulator with a displaceable piston, the at least one piston accumulator having a third interior space fluidly connected to the second interior space and a fourth interior space fluidly connected to the fluid region, the piston sealing the third interior space from the fourth interior space, wherein the pressure compensation device is configured to raise a pressure level of the fluid region to between 0.5 and 10 bar greater than the ambient pressure prevailing in the seawater region, and wherein the pressure compensation device is constructed in two stages in such a way that the at least one accumulator and the at least one piston accumulator are arranged in series.

2. The pressure compensation device as claimed in claim 1, wherein the at least one accumulator with the flexible wall region includes one of a diaphragm accumulator and a bladder accumulator.

3. The pressure compensation device as claimed in claim 1, further comprising: at least one compression spring configured to load the piston of the piston accumulator.

4. The pressure compensation device as claimed in claim 3, wherein the at least one spring loads the piston in a direction towards increasing the pressure level of the fluid region so as to increase the pressure level to between 0.5 and 10 bar greater than the ambient pressure.

5. The pressure compensation device as claimed in claim 1, further comprising: a displacement transducer configured to monitor a position of the piston of the piston accumulator.

6. The pressure compensation device as claimed in claim 1, wherein the piston of the piston accumulator comprises a plurality of downstream sealing devices.

7. The pressure compensation device as claimed in claim 1, wherein the second interior space and the third interior space form an interspace that is defined by the at least one accumulator with the flexible wall region and by the at least one piston accumulator, the interspace being filled with a transmission medium.

8. The pressure compensation device as claimed in claim 1, wherein the pressure compensation device is configured as a hollow cylinder in which the at least one accumulator includes an inner accumulator that has a flexible bladder forming the flexible wall region and the at least one piston accumulator includes an outer accumulator that surrounds the inner accumulator.

9. An arrangement comprising: a hollow cylinder configured as a drum and defining a central opening configured to guide an actuating shaft of an electronic or hydraulic component, the hollow cylinder defining a plurality of bores; and a plurality of pressure compensation devices configured to seal a housing with respect to a surrounding seawater region, said housing forming a fluid region, each pressure compensation device arranged in an associated one of the plurality of bores, each pressure compensation device comprising: at least one accumulator with a flexible wall region; and at least one piston accumulator with a displaceable piston, wherein the plurality of pressure compensation devices are configured to raise a pressure level of the fluid region at least to the ambient pressure prevailing in the seawater region, and wherein each pressure compensation device is constructed in two stages in such a way that the at least one accumulator and the at least one piston accumulator are arranged in series.

10. A method of using a pressure compensation device comprising: pressurizing at least one fluid-filled housing for a hydraulic actuating shaft of one of an electric motor, a pump, and a cylinder compensator with the pressure compensation device to a pressure level that is between 0.5 and 10 bar greater than the ambient pressure prevailing in a surrounding seawater region, the pressure compensation device including: at least one accumulator with a flexible wall region, the at least one accumulator defining a first interior space fluidly connected to the seawater region and a second interior space separated from the first interior space by the flexible wall region; and at least one piston accumulator with a displaceable piston, the at least one piston accumulator having a third interior space fluidly connected to the second interior space and a fourth interior space fluidly connected to the fluid region, the displaceable piston sealing the third interior space from the fourth interior space, wherein the pressure compensation device is constructed in two stages in such a way that the at least one accumulator and the at least one piston accumulator are arranged in series.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure and the technical field are explained in more detail below with reference to figures. Here, identical components are designated by identical reference signs. The illustrations are schematic and not intended to illustrate size relationships. The explanations set out with respect to individual details of a figure can be extracted and freely combined with technical matters from other figures or the present description, unless something else necessarily results for a person skilled in the art or such a combination is explicitly forbidden here. In the drawings:

(2) FIG. 1 shows a circuit diagram of a pressure compensation device having—arranged in series—a diaphragm accumulator and a piston accumulator,

(3) FIG. 2 shows a block diagram of a pressure compensation device between seawater region and (inner) fluid region,

(4) FIG. 3 shows a circuit diagram of a pressure compensation device having two diaphragm accumulators and three piston accumulators which are in each case arranged parallel to one another,

(5) FIG. 4 shows a structural embodiment of a pressure compensation device, and

(6) FIG. 5 shows an arrangement of a plurality of pressure compensation devices in a common drum-like holding element.

DETAILED DESCRIPTION

(7) FIG. 1 shows the basic illustration of a circuit diagram of a pressure compensation device 1 having—arranged and connected in series—an accumulator 2 with a flexible wall region 4 and a piston accumulator 3 with a displaceable piston 5. The accumulator 2 with flexible wall region 4 is explained in FIGS. 1, 2 and 3 using the example of a diaphragm accumulator and in FIGS. 4 and 5 using the example of a bladder accumulator. Furthermore, the flexible wall 4 is explained in FIGS. 1, 2 and 3 using the example of a nonpenetrable diaphragm 9 and in FIGS. 4 and 5 using the example of a nonpenetrable bladder 23.

(8) The diaphragm accumulator 2 has an (inlet-side) first interior 2.1 and an (outlet-side) second interior 2.2 which are separated from one another and sealed with respect to one another by a flexible wall region 4, for example an elastic metal diaphragm (or, according to FIG. 4, a rubber bladder). The piston accumulator 3 has an (inlet-side) first interior 3.1 and an (outlet-side) second interior 3.2 which are separated from one another by the displaceable piston 5 and sealed with respect to one another by means of seals. Reference sign 6 designates in dot-dash line a schematic separating line, on the right-hand side of which the seawater region 7 is situated and on the left-hand side of which the (inner) fluid region 8 is situated. A filter 35 for the seawater is arranged upstream of the diaphragm accumulator. The seawater filter can serve to avoid a situation in which dirt particles clog the bore to the diaphragm. Furthermore, the displaceable piston 5 of the piston accumulator 3 is assigned a displacement transducer 10.

(9) FIG. 2 illustrates a block diagram of the pressure compensation device 1, for example also according to FIG. 1, between the seawater region 7 and the fluid region 8. The first interior 2.1 of the diaphragm accumulator 2 is connected to the seawater region 7, and the second interior 3.2 of the piston accumulator 3 is connected to the fluid region 8. The second interior 2.2 of the diaphragm accumulator 2 and the first interior 3.1 of the piston accumulator 3 functionally form a common interspace 11. The interspace 11 can be structurally designed as a single space. The interspace 11 can also consist of two individual spaces, that is to say of the second interior 2.2 and the first interior 3.1, which are interconnected by a pipeline or the like. A first boundary, formed by for example a diaphragm 9, is designated by 12, and a second boundary, formed by for example a piston 5, is designated by 13. The two boundaries 12, 13 form a two-fold safeguard (redundancy) against penetration of seawater into the fluid region 8.

(10) The first interior 2.1 of the diaphragm accumulator 2 is filled with seawater (first medium 27) which loads the one side of the diaphragm 9 with the ambient pressure prevailing in the water. The water pressure in the seawater region 7 and in the first interior 2.1 is equal. The interspace 11 contains a second medium 28 (transmission medium), for example a hydraulic fluid, a grease-like substance, a dielectric transformer oil or a gas, in particular nitrogen. The second medium 28 is pressurized by the other side of the diaphragm 9, with the result that the interspace 11 forms an intermediate pressure space. Furthermore, the pressure of the medium loads the one side of the piston 5 of the piston accumulator 3. The second interior 3.2 of the piston accumulator 3 is filled with a third medium 29, preferably with transformer oil. Here, the other side of the piston 5 exerts pressure on the medium 29. This pressure simultaneously acts on the medium 29 which fills the (not shown) downstream devices, for example tank or housing. Consequently, the pressure in the inner fluid region 8 and in the second interior 3.2 of the piston accumulator 3 is equal.

(11) The system device arranged downstream of the pressure compensation device 1 can take the form of a container-like module, wherein a plurality of such modules can be deposited on the seabed. The container is filled with a dielectric liquid, for example a hydraulic oil, with the result that all the components in the module are immersed in the liquid. The pressure compensation device 1 achieves pressure compensation between the inside of the container and the external surroundings (seawater region 7) in such a way that the liquid in the container is placed under the same pressure as prevails in the external surroundings. For this purpose, the pressure compensation device 1 has two separating surfaces or boundary surfaces: a flexible separating element (diaphragm 9 or bladder 23) which is in contact on its one side with the seawater, and a piston 5 which is subjected on its other side to the action of the liquid which is situated in the container. The interspace 11 is arranged between the two separating elements. The pressure compensation device 1 presented here has the particular advantage that seawater which has penetrated unintentionally through the diaphragm 9 does not pass (directly) into the container but, hampered by the piston 5, remains in the interspace 11 and can be removed there. There is thus present a double safeguard against penetrated seawater. An additional further safeguard consists in the fact that the piston 5 of the piston accumulator 3 is acted upon by a compression spring 22 (see also FIG. 4), with the result that the medium 29 is under a prestress. The prestress pressure is slightly greater than the ambient pressure, for example 0.5 to 10 bar, thereby preventing seawater from penetrating into the downstream device. To detect a leakage in the piston accumulator 3, the piston 5 is assigned the displacement transducer 10 which monitors the position of the piston 5.

(12) FIG. 3 shows a circuit diagram of a pressure compensation device, such as, for example, also according to FIG. 1, but with two diaphragm accumulators 2a, 2b and three piston accumulators 3a, 3b, 3c which are in each case arranged and connected parallel to one another. There is in this way realized a greater volume of the interiors of the diaphragm accumulators 2a, 2b and of the piston accumulators 3a, 3b, 3c.

(13) FIG. 4 illustrates a structural embodiment of a pressure compensation device 1, in particular also according to the circuit diagram illustrated in FIG. 1. The embodiment is distinguished by the fact that the accumulator 2 with the flexible wall region 4 and the piston accumulator 3 are formed in the manner of a compact cylinder, with the result that a particularly space-saving design is realized. The pressure compensation device 1 is designed in the manner of a hollow cylinder in such a way that an inner bladder accumulator 2 is surrounded by an outer piston accumulator 3. As FIG. 4 illustrates, the piston accumulator 3 consists of a cylinder tube 14 and a piston 5 as separating element. A closure cover 15, which has a central through-opening 16, is present on a first end side 14.1 of the cylinder tube 14. A central through-opening 18, which opens with the inner fluid region, is present on the other second end side 14.2 of the cylinder tube 14. The piston 5 is sealed with respect to the inner lateral surface 14.3 of the cylinder tube 14 by means of seals 19. A first hollow cylinder 20 grows out of the surface of the piston 5 that faces the opening 16, and a further hollow cylinder 21 grows out of the surface of the closure cover 15 that faces the opening 18, the open ends of which cylinder overlap one another. Between the outer first hollow cylinder 21 and the inner lateral surface 14.3 there is arranged a compression spring 22 which is supported by the one end on the closure cover 15 and by the other end on the piston 5. In the inner cavity formed by the hollow cylinders 20 and 21 there is situated a bladder 23, for example consisting of an elastomer, of a bladder accumulator 2, which bladder serves as a separating wall. The bladder 23 has two (axially) opposite end regions, with—in each case at a distance—the end regions being situated opposite to the piston 5 or to the closure cover 15 and the central region being situated opposite to the hollow cylinders 20, 21 in such a way that an interspace 11 is formed. The lower end region of the bladder 23 transitions into a hollow cylinder-like through-connection 24 with an opening 34 for the passage of seawater (first medium 27), said connection engaging through the opening 16.

(14) The mode of operation is such that a pressure-loaded first medium 27 (seawater) fills the bladder 23, which widens under the pressure and thus in turn displaces a second medium 28 outside the bladder 23. This medium 28 in turn is braced between the bladder 23 and the piston 5 and drives the latter in the axial direction (cylinder function) by the widening of the bladder 23 and the medium 28. The piston 5 is additionally sealed with respect to the cylinder tube 14 by means of a piston seal (redundant). The piston 5 is preloaded by a compression spring 22 and thus ensures prestressing of the system with respect to the pressure of the first medium 27. Consequently, a medium on the piston side, which can be a third medium 29 or else the same medium as the second medium 28, is loaded (on the outlet side) separately from and with a prestress with respect to the first medium 27.

(15) There can optionally be provided safeguarding of the pressure compensation against possible escape of first medium 27 caused by damage to the bladder 23 upon complete unloading of the prestress (piston 5 in the end position) and upon pressure equalization, for example leakage of the piston seal 19. The piston 5 of the pressure compensation is moved by the spring 22 into the end position and thus closes the opening 18 at the outlet by means of an (annular) seal 25 on the piston 5. Here, a cylindrical projection 30 on the piston 5 preferably engages in the opening 18 in a form-fitting manner.

(16) Furthermore, safeguarding can optionally be present by means of an additional sealing ring 31 on the piston 5 that, for example, swells by contact with a medium other than the operating fluid or transmission fluid. The swelling of the sealing ring 31 results in a form fit which produces sealing tightness between the piston 5 and the cylinder tube 14.

(17) The pressure compensation serves for equalizing two pressures in a system which operate with media which are used separately from one another, such as oil and water, for example. This pressure compensation makes it possible by means of the spring 22 to prestress one side with higher pressure so as to prevent the other medium with lower pressure penetrating into the system. Moreover, the separation is redundant since two different methods of separation of liquid or gaseous media are arranged in series here without requiring a relatively large space requirement.

(18) FIG. 5 shows an arrangement for a plurality of pressure compensation devices 1 (for example according to FIG. 4) in a common holding element. The pressure compensation devices 1 are arranged parallel to one another in the longitudinal direction. In this way, a relatively large volume for the pressure compensation (redundancy) is realized. A hollow cylinder 32 in the manner of a drum-half-cut-open in FIG. 5—has a cylinder jacket 32.1 (hollow cylinder wall) and a cylinder interior 32.2. The cylinder jacket 32.1 is penetrated by a plurality of through-bores 33.1, 33.2 which are oriented parallel to the center axis in the longitudinal direction and into each of which a pressure compensation device 1 is plugged in a form-fitting manner. FIG. 5 illustrates—in a half-cut-open view—only one pressure compensation device 1 arranged in a bore 33. The hollow cylinder 32 is formed as a drum in a similar manner to a revolver magazine.

(19) The pressure compensation device 1 according to FIG. 5 can be used to apply ambient pressure (water pressure) to an integrated hydraulic actuating shaft 17 (electric motor, pump, cylinder compensator) in its oil-filled housing. For this purpose, the (plurality of) pressure compensators 1 are accommodated in a type of drum. The cylinder or a rod of the cylinder can be guided through the central opening or the cylinder interior 32.2 of the drum, thus allowing a space-saving integrated design.

LIST OF REFERENCE SIGNS

(20) 1 Pressure compensation device 2, 2a, 2b Accumulator with flexible wall region 2.1 First interior 2.2 Second interior 3, 3a to 3c Piston accumulator 3.1 First interior 3.2 Second interior 4 Flexible wall region 5 Piston 6 Separating line 7 Seawater region 8 Fluid region 9 Diaphragm 10, 10a, 10b Displacement transducer 11 Interspace 12 First boundary 13 Second boundary 14 Cylinder tube 14.1 First end side 14.2 Second end side 14.3 Inner lateral surface 15 Closure cover 16 Opening 17 Actuating shaft 18 Opening 19 Seal 20 First hollow cylinder 21 Second hollow cylinder 22 Compression spring 23 Bladder 24 Connection 25 Seal 26 Seal 27 First medium 28 Second medium 29 Third medium 30 Projection 31 Sealing ring 32 Hollow cylinder 32.1 Cylinder jacket 32.2 Cylinder interior 33.1, 33.2 Bores 34 Opening 35 Filter