DE102018217369A1 - Pressure compensation device set up for underwater applications - Google Patents

Abstract

The invention relates to a pressure compensation device (1), set up for underwater applications, with which an interior of a container (39), which forms a fluid area (8), can be sealed off from the surrounding seawater area (7), with the pressure compensation device (1) a pressure level of the fluid area (8) can be raised at least to the ambient pressure prevailing in the sea water area (7), the pressure compensation device (1) being constructed in such a way that at least two stores (2; 2a, 2b) with a flexible wall area (4) in series are arranged, the at least two stores (2; 2a, 2b) being arranged in an annular pressure chamber of a housing (27). The use of the pressure compensation device (1) for pressurizing containers (39) filled with at least one fluid for a hydraulic actuating axis (37) is also proposed.

Description

The present invention relates to a pressure compensation device for a hydraulic system, set up for underwater applications.

Such types of hydraulic systems can be used to move an element under water at water depths up to several thousand meters in connection with the extraction of oil and natural gas, mining, scientific inquiries or infrastructure projects. For example, in the case of crude oil or natural gas production facilities at sea, process valves are located at great depths with which the volume flow of the medium to be extracted can be regulated or shut off.

The use of hydraulic and / or electrical and / or mechanical components under water, especially at great depths, is problematic because the components can be damaged by water, in particular sea water. In particular, the high ambient pressure of the water requires pressure compensation. For this, hydraulic pressure compensators can be used, which can raise the pressure level of a hydraulic system used in the underwater area to the ambient pressure prevailing in the water. For this purpose, membranes can be used which are exposed to ambient sea water on one side and which are connected to a reservoir of the hydraulic system on the other side. A disadvantage of this arrangement is that if the membrane, which forms an interface, is damaged, seawater can penetrate into the hydraulic system.

Proceeding from this, it is the object of the present invention to create a device and to specify a use which alleviate or even avoid the disadvantages mentioned. In particular, a penetration of sea water into the hydraulic system should be reliably avoided in a structurally simple manner. Furthermore, the operating time of the pressure compensation device is to be increased significantly. In addition, a space-saving arrangement of hydraulic cylinders or drive spindles should be made possible.

These objects are achieved with a device or a use according to the independent patent claims. Further embodiments of the invention are specified in the dependent claims. It should be pointed out that the description, in particular in connection with the figures, give further details and developments of the invention, which can be combined with the features from the patent claims.

A pressure compensation device, which is set up for underwater applications, contributes to this. It serves to seal an interior of a housing, which itself forms an (inner) fluid area, from the surrounding sea water area, the pressure compensation device being able to raise a pressure level of the fluid area at least to the ambient pressure prevailing in the sea water area. The hydraulic system, which is set up for underwater applications, can consequently comprise an interior of a container (for example a hydraulic and / or electrical component, such as an electric motor, a pump, a tank or the like), which forms a fluid region which is opposite the surrounding sea water area is sealed. For this purpose, the at least one hydraulic pressure compensation device is provided, which can raise the pressure level of the fluid (hydraulic fluid, transformer oil, lubricant, etc.) in the fluid area at least to the ambient pressure prevailing in the (surrounding) sea water area.

The pressure compensation device is constructed in at least two stages in such a way that at least two stores with a flexible wall area are arranged in series.

The device proposed here for a system filled under water with a fluid (or hydraulic system or electrical system with transformer oil or mechanical system with lubricant) has the particular advantage that underwater pressure compensation with an at least double (redundant) barrier against intrusion is realized by sea water. The at least two barriers are arranged and connected in series. In other words, this means in particular that the at least one reservoir with the flexible wall area can be acted upon by the sea water, as a result of which the flexible wall is movable in response to the sea water pressure. The movement of the flexible wall can then be transferred (separated from the direct influence of the sea water) to a movement of the flexible wall area in the subsequent store. A transmission medium, in particular a liquid, which is arranged in the memory, can be used for this. The (resulting) movement of the flexible wall area can (directly) lead to a pressure adjustment in the fluid area, for which the flexible wall area is preferably in direct contact with the fluid area. As a result, with this arrangement, two separate component failures (in the first reservoir and the second reservoir) would have to occur before sea water can enter the interior of the system. The device is therefore characterized by high reliability, so that the system is designed for 20 years and more operating time, for example, and requires a minimum, preferably no maintenance.

The internal fluid (for example a hydraulic medium, transformer oil or lubricant) is isolated and can therefore have an essentially equal or even higher pressure than the environment (for example sea water). The two barriers (flexible walls) mean that the seawater has to pass two sealing points (membrane or bubbles) before it can penetrate the system (redundancy to prevent system errors).

The fact that the at least two reservoirs, each with a flexible wall area, is arranged in an annular pressure chamber of a housing, reliably prevents seawater from penetrating into the hydraulic system in a structurally simple manner. In particular, the pressure compensation capacity is significantly increased and the installation space is reduced.

The annular pressure chamber of the housing is preferably designed as a hollow cylinder arrangement with two hollow cylinders arranged coaxially to one another, between which there is an intermediate cavity.

Advantageously, the at least two stores with a flexible wall area are (completely) arranged in the intermediate cavity.
The at least two stores with a flexible wall area are preferably ring-shaped.

At least one of the memories can e.g. B. span an annular intermediate cavity.

It is possible for a plurality or a plurality of two-stage storage systems of the type described to be arranged distributed over a circumference of an annular intermediate cavity.

It is further preferred that the number of stores with flexible wall areas which are arranged in a row is not very high, for example is 2, 3 or a maximum of 4. The technical outlay for production can thus be limited.

The reservoir (which is actively connected to the sea water) with a flexible wall area can be a membrane reservoir or a bladder reservoir. In the case of a diaphragm accumulator, a diaphragm can be provided, which is essentially plate-shaped, the periphery (fixed) of which is connected to a storage wall, and which is movable radially on the inside in response to a pressure prevailing there. A bladder accumulator can be designed with a flexible wall, which encloses a predeterminable bladder accumulator volume and can move axially and radially in the direction of a pressure prevailing there. The flexible wall and / or the membrane are particularly fluid-tight and resistant to contact with sea water under high pressure.

A flexible wall area is expediently loaded by at least one compression spring.

A piston accumulator with a displaceable piston is preferably arranged in series between the accumulators with a flexible wall area.

The piston of the piston accumulator is expediently loaded by at least one compression spring. The compression spring can be used to set a predeterminable prestress, for example to set a pressure level that is higher than the pressure generated by the seawater on the fluid region. The piston is in particular designed with a rigid piston plate on which the compression spring acts. Damage or overloading of this rigid piston due to the pressure spring load can thus be permanently avoided.

The fluid is preferably biased in the fluid region with respect to the pressure of the surrounding sea water region with 0.5 to 10 bar. For this purpose, a correspondingly designed compression spring can be provided in the piston accumulator, with which the prestress above the seawater pressure level can be adjusted.

A displacement sensor is advantageously assigned to the piston of the piston accumulator. The displacement sensor is in particular set up to detect the current stroke or the current position of the piston with reference to a reference position or the piston accumulator. A sensor in this sense is in particular a sensor by means of which a position of the piston can be determined or measured directly / indirectly. The sensor can include an end position switch, a pressure switch. This enables monitoring of a possible leakage by observing the position of the piston, for example if a movement of the piston is determined under unchanged pressure conditions.

The piston of the piston accumulator can comprise a plurality of sealing devices arranged downstream (in the effective direction of the pressure). The piston can preferably seal an opening of a second interior of the piston accumulator from the fluid region. Compared to a cylinder tube (piston cylinder housing), the piston can additionally have at least one seal that swells (when in contact with sea water).

It is preferred that the at least two accumulators with a flexible wall area and the at least one piston accumulator form an intermediate space which is filled with a transmission medium (fluid and / or gas). Advantageously, a (output side) second interior of a membrane or bladder accumulator and a (input side) first interior of a piston accumulator form an (partially or completely) intermediate space filled with a fluid and / or gas. The fluid (or transmission fluid) in the (output-side) second interior of the accumulator with a flexible wall area and the (input-side) first interior of the piston accumulator is preferably a hydraulic fluid, a mechanical grease-like medium or a dielectric transformer oil.

The fluid in the (interior) second interior of the piston accumulator and in the fluid area is advantageously an oil, in particular a transformer oil.

The pressure compensation device is further preferably designed in the manner of a hollow cylinder in such a way that the at least two stores with a flexible wall area are surrounded by an outer hollow cylinder jacket and are arranged opposite an inner hollow cylinder jacket.

An arrangement with the pressure compensation device presented here is expediently arranged in a hollow cylinder arrangement with a hollow cylinder interior, through the central opening of which an actuating axis of an electronic or hydraulic component can be guided. The central passage opening can be arranged (sealingly) around the setting axis of an electronic or hydraulic component (electric motor, pump, cylinder compensation, etc.).

According to another aspect, the use of a pressure compensation device proposed here for pressurizing at least one container filled with fluid (for example with hydraulic fluid, oil, grease, lubricant, etc.) is proposed for a hydraulic actuating axis of an electric motor, a pump and / or a cylinder compensation . The at least one pressure compensation device is used in particular to apply ambient pressure (water pressure) to an integrated hydraulic actuating axis (electric motor, pump, cylinder compensation) in its oil-filled container. The cylinder or a rod of the cylinder can be guided through the central opening of the housing, which enables a space-saving integrated construction.

• 1: Querschnitt durch eine erste Ausführungsform der Druckkompensationseinrichtung mit zwei Blasenspeichern und einer Kolbenspeichereinrichtung in einem ringförmigen Hohlraum;
• 2: einen Schaltplan einer Druckkompensationseinrichtung wie 1, jedoch mit - in Reihe angeordnet - zwei Membranspeichern und einem Kolbenspeicher;
• 3: Blockschaltbild der Druckkompensationseinrichtung nach 1 zwischen Seewasser- und (innerem) Fluidbereich;
• 4: Querschnitt durch eine weitere Ausführungsform der Druckkompensationseinrichtung mit zwei Membranspeichern in einem Ringraum; und
• 5: perspektivisch im Schnitt den ringförmigen Druckraum (Zwischen- hohlraum) eines Gehäuses als Teil der Druckkompensationseinrichtung.

The measures proposed here are based in particular on the idea of forming an at least two-stage pressure compensator with at least two bladder or membrane accumulators, which forms the interface between seawater and intermediate pressure space, and a piston or spring-piston accumulator, which establishes contact with the hydraulic reservoir. Instead of one, there are now at least two interfaces; this increases the tightness and durability. In addition, a preload above the seawater pressure level can be set by a spring in the piston or spring piston accumulator.
The invention and the technical environment are explained in more detail below with reference to figures. The same components are identified by the same reference numerals. The representations are schematic and are not intended to illustrate size relationships. The explanations given with reference to individual details of a figure are extractable and can be freely combined with facts from other figures or the above description, unless something different arises for a person skilled in the art or such a combination is explicitly prohibited. They show schematically:

• 1 : Cross section through a first embodiment of the pressure compensation device with two bladder accumulators and a piston accumulator device in an annular cavity;
• 2nd : a circuit diagram of a pressure compensation device such as 1 , but with - arranged in series - two diaphragm accumulators and one piston accumulator;
• 3rd : Block diagram of the pressure compensation device according to 1 between seawater and (inner) fluid area;
• 4th : Cross-section through a further embodiment of the pressure compensation device with two diaphragm accumulators in an annular space; and
• 5 : Perspective in section, the annular pressure space (intermediate cavity) of a housing as part of the pressure compensation device.

1 shows a cross section through a first embodiment of the pressure compensation device 1 with a first store 2a with flexible wall area and a second store 2 B with flexible wall area, both storage 2a and 2 B as a bladder accumulator with a bladder 18th respectively. 19th are designed as a flexible wall area. The bubble 18th has a first opening 16 to the lake water area 7 and the bubble 19th has a second opening 17th to the fluid area 8th on. Between the first store 2a and the second memory 2 B is a piston accumulator 3rd with a spring-loaded piston 5 arranged. With 11 is a space between the Outside walls of the first bubble 18th and the second bubble 19th referred to, which is filled with a transmission medium. The pressure compensation device 1 is constructed in such a way that the two memories 2a and 2 B , the piston accumulator 3rd and the space 11 in an annular pressure space (intermediate cavity 36 , please refer 5 ) of a housing 27 are arranged.

2nd shows the basic representation of a circuit diagram of a pressure compensation device 1 with - arranged and connected in series - two stores 2a , 2 B with a flexible wall area 4th and a piston accumulator 3rd with a sliding piston 5 . The stores 2a , 2 B with flexible wall area 4th are in the 1 using the example of two bladder accumulators and in the 4th explained using the example of two membrane accumulators. Furthermore, the flexible wall 4th in the 1 using the example of an impenetrable bubble and in 4th explained using the example of an impenetrable membrane.

The first store 2a (Membrane accumulator) has a (interior) first interior 2.1 and a (interior) second interior 2.2 on through a flexible wall area 4th , for example an elastic metal membrane (or according to 1 a rubber bladder), separated from each other and sealed against each other. The second store 2 B (Membrane accumulator) corresponds to the first membrane accumulator 2a built, with a third interior 2.3 and a fourth interior 2.4 are present through a flexible wall area 4th are separated. The piston accumulator 3rd has a (interior) first interior 3.1 and a (interior) second interior 3.2 by the sliding piston 5 are separated from each other and sealed against each other by seals. With 6 is a dash-dot line shows a schematic dividing line, on the right side of which is the seawater area 7 and on the left side is the (inner) fluid area 8th located. The first store 2a is a filter 38 upstream for the seawater. The sea water filter can serve to prevent dirt particles from drilling into the membrane 9.1 clog. Furthermore, the sliding piston 5 of the piston accumulator 3rd a pioneer 10th assigned. With 39 is called a container.

3rd illustrates a block diagram of the pressure compensation device 1 , for example according to 1 , between the sea water area 7 and the fluid area 8th . The first interior 2.1 of the first memory 2a stands with the sea water area 7 and the fourth interior 2.4 of the second memory 2 B stands with the fluid area 8th in connection. The second interior 2.2 of the membrane accumulator 2a and the first interior 3.1 of the piston accumulator 3rd functionally form a common space 11 . The gap can be constructive 11 be designed as a single room. The gap 11 can also consist of two separate rooms, i.e. the second interior 2.2 and the first interior 3.1 exist, which are connected to each other by a pipeline or the like. With 12th is a first boundary, for example a membrane 9.1 and at 13 is a second boundary, for example a membrane 9.2 , designated. The two borders 12th , 13 form a double security (redundancy) against the ingress of sea water into the fluid area 8th .

The first interior 2.1 of the first memory 2a is with sea water (first medium 24th ) filled with one side of the membrane with the ambient pressure prevailing in the water 9.1 charged. The water pressure in the sea water area 7 and in the first interior 2.1 is equal to. In the gap 11 there is a second medium 25th (Transmission medium), for example a hydraulic fluid, a grease-like substance, a dielectric transformer oil or a gas, in particular nitrogen. The second medium 25th is through the other side of the membrane 9.1 pressurized so that the space 11 forms an intermediate pressure space. The pressure of the medium 25th continues to stress one side of the second membrane 9.2 . The second interior 3.2 of the piston accumulator 3rd is filled with a medium, preferably with transformer oil.

That of the pressure compensation device 1 Downstream system equipment can be used as a container-like module, for example a container 39 (see. 2nd ), be formed, wherein several such modules can be placed on the seabed. The container is filled with a dielectric liquid, for example hydraulic oil, so that all components in the module are immersed in the liquid. Through the pressure compensation device 1 pressure compensation between the interior of the container and the external environment (sea water area 7 ) achieved in such a way that the liquid in the container is pressurized to the same pressure as that prevailing in the external environment. For this purpose, the pressure compensation device has 1 at least two separating surfaces or interfaces: a flexible separating element (membrane 9 or bubble), which is in contact with the sea water on one side, and a flexible separating element (membrane 9 or bubble), which is on its other side acted upon by the liquid that is in the container. The gap is between the two separating elements 11 arranged. The pressure compensation device presented here 1 has the particular advantage that unintentionally through the membrane 9.1 penetrated seawater does not (directly) get into the container, but is prevented by the piston 5 in the space 11 remains and can be removed there. It there is therefore a double security against ingress of sea water. An additional additional safeguard is that the piston 5 of the piston accumulator 3rd by a compression spring 14 is acted upon, causing the medium 25th is under a bias. The preload pressure is slightly higher than the ambient pressure, for example 0.5 to 10 bar, so that sea water cannot penetrate into the downstream device. For a leak in the piston accumulator 3rd the piston is to be detected 5 the pathfinder 10th assigned the position of the piston 5 supervised.

4th illustrates a further embodiment of the pressure compensation device 1 with a first store 2a and a second memory 2 B , the two stores 2a and 2 B are designed as a membrane accumulator. As a flexible wall area 4th assigns the first memory 2a a first membrane 9.1 and the second store 2 B a second membrane 9.2 on. The first flexible membrane 9.1 is on a first membrane plate 22 , for example an unyielding sheet, and the second flexible membrane 9.2 is on a membrane plate 23 supported. In the first interior 2.1 is a compression spring 15 present, one end of which on the membrane plate 22 and the other end in a recess 28 in the cover plate of the housing 27 is supported. They are in the first interior 2.1 a first medium 24th (Sea water), in the gap 11 a second medium 25th (for example transformer oil) and in the fourth interior 2.4 a third medium 26 (Fluid, for example hydraulic oil).

5 shows a perspective view in section of the annular pressure chamber (between the cavity 36 ) of a housing 27 as part of the pressure compensation device 1 . It is an arrangement for a pressure compensation device 1 (for example according to 1 and 4th ) present in a common holding element. A hollow cylinder arrangement 29 - in 5 cut in half - has a hollow cylinder jacket 31 and a hollow cylinder interior 30th on. The housing 29 the pressure compensation device 1 has the shape of the hollow cylinder arrangement 29 . The second opening 17th is on a container 39 , for example a container-like module, via a second connection 21 , for example a pipe. The first opening 16 , for example a hole, is over a first connection 20th , for example a pipe, the sea water area 7 assigned. The hollow cylinder arrangement 29 consists of an external (first) hollow cylinder 32 and an inner (second) hollow cylinder arranged coaxially thereto 33 together, which is an external hollow cylinder jacket 34 or an internal hollow cylinder jacket 35 exhibit. Between the outer hollow cylinder jacket 34 and the inner hollow cylinder jacket 35 , ie in the cylinder jacket 31 of the hollow cylindrical housing 27 , is coaxial an annular intermediate cavity 36 available. In the intermediate cavity 36 are according to 1 at least two stores 2a , 2 B (Bladder accumulator) and a piston accumulator 3rd or according to 4th two stores 2a , 2 B (Membrane accumulator) arranged.

In a central opening in the hollow cylinder space 30th is a control axis shown in dashed lines 37 , for example a (not shown) hydraulic cylinder or a (not shown) drive spindle arranged to save space.

Reference list

1

Pressure compensation device

2nd

Storage with flexible wall area

2a

first store with flexible wall area

2 B

second store with flexible wall area

2.1

first interior of 2a

2.2

second interior of 2a

2.3

third interior of 2 B

2.4

fourth interior of 2 B

3rd

Piston accumulator

3.1

first interior of 3rd

3.2

second interior of 3rd

4th

flexible wall area

5

piston

6

parting line

7

Sea water area

8th

Fluid area

9

membrane

9.1

first membrane

9.2

second membrane

10th

Displacement sensor

11

Space

12th

first limit

13

second limit

14

first compression spring

15

second compression spring

16

first opening

17th

second opening

18th

first bubble

19th

second bubble

20th

first connection

21

second connection

22

first membrane plate

23

second membrane plate

24th

first medium

25th

second medium

26

third medium

27

casing

28

Recess

29

Hollow cylinder arrangement

30th

Hollow cylinder interior

31

Hollow cylinder jacket

32

external hollow cylinder

33

internal hollow cylinder

34

external hollow cylinder jacket

35

internal hollow cylinder jacket

36

Intermediate cavity

37

Positioning axis

38

filter

39

container

Claims (13)

Pressure compensation device (1), set up for underwater applications, with which an interior of a container, which forms a fluid area (8), can be sealed off from the surrounding seawater area (7), the pressure compensation device (1) being used to set a pressure level of the fluid area (8) at least to the ambient pressure prevailing in the seawater area (7), the pressure compensation device (1) being constructed in such a way that at least two stores (2; 2a, 2b) with a flexible wall area (4) are arranged in series, the at least two Stores (2; 2a, 2b) are arranged in an annular pressure chamber of a housing (27). Pressure compensation device (1) Claim 1 The annular pressure chamber of the housing (27) is designed as a hollow cylinder arrangement (29) with two hollow cylinders (32, 33) arranged coaxially to one another, between which an intermediate cavity (36) is present. Pressure compensation device (1) Claim 2 The at least two stores (2; 2a, 2b) with a flexible wall area (4) are arranged in the intermediate cavity (36). Pressure compensation device (1) according to one of the preceding claims, wherein the at least two stores (2; 2a, 2b) with a flexible wall area (4) are annular. Pressure compensation device (1) according to one of the preceding claims, wherein at least one memory (2; 2a, 2b) with a flexible wall area (4) is a membrane memory or bladder memory. Pressure compensation device (1) according to one of the preceding claims, wherein a flexible wall area (4) is loaded by at least one compression spring (15). Pressure compensation device (1) according to one of the preceding claims, wherein a piston accumulator (3) with a displaceable piston (5) is arranged in series between the accumulators (2; 2a, 2b) with a flexible wall area (4). Pressure compensation device (1) according to one of the preceding claims, wherein the piston (5) of the piston accumulator (3) is loaded by at least one compression spring (14). Pressure compensation device (1) according to one of the preceding claims, wherein a displacement sensor (10) is assigned to the piston (5) of the piston accumulator (3). Pressure compensation device (1) according to one of the preceding claims, wherein an intermediate space (11) which is filled with a transmission medium is formed between the at least two stores (2; 2a, 2b) with a flexible wall area (4). Pressure compensation device (1) according to one of the preceding claims, it being designed in such a way that the at least two stores (2; 2a, 2b) with a flexible wall area (4) are surrounded by an external hollow cylinder jacket (34) and an internal hollow cylinder jacket (35) are arranged opposite one another. Arrangement comprising the pressure compensation device (1) according to one of the preceding claims, which is arranged in the intermediate cavity (36) of a hollow cylinder arrangement (29), through the central opening of which an actuating axis (37) of an electrical or hydraulic component can be guided. Use of the pressure compensation device (1) according to one of the preceding claims for pressurizing at least one container (39) filled with fluid for one hydraulic actuating axis (37) of an electric motor, a pump or a cylinder compensation.

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