WO2020074431A1

WO2020074431A1 - Pressure compensation device designed for underwater applications

Info

Publication number: WO2020074431A1
Application number: PCT/EP2019/077056
Authority: WO
Inventors: Alexandre ORTH; Juergen Schneider; Gottfried Hendrix
Original assignee: Robert Bosch Gmbh
Priority date: 2018-10-11
Filing date: 2019-10-07
Publication date: 2020-04-16
Also published as: EP3864302B1; EP3864302A1; DE102018217369A1

Abstract

The invention relates to a pressure compensation device (1) designed for underwater applications and by means of which an interior of a container (39), which forms a fluid region (8), can be sealed with respect to the surrounding seawater region (7), wherein a pressure level of the fluid region (8) can be raised at least to the surrounding pressure prevailing in the seawater region (7) by the pressure compensation device (1), wherein the pressure compensation device (1) is constructed in such a way that at least two accumulators (2; 2a, 2b) having a flexible wall region (4) are arranged in series, wherein the at least two accumulators (2; 2a, 2b) are arranged in an annular pressure space of a housing (27). Also proposed is the use of the pressure compensation device (1) for pressurizing at least one fluid-filled container (39) for a hydraulic actuating shaft (37).

Description

Pressure compensation device set up for underwater applications

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 should be structurally simple hydraulic system can be reliably avoided. 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 first the at least one reservoir with the flexible wall area with the sea water is acted upon, whereby 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 a high level of reliability, so that the system is designed, for example, for 20 years and more of operating time 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).

Due to the fact that the at least two reservoirs, each with a flexible wall area, are arranged in an annular pressure chamber of a housing, penetration of seawater into the hydraulic system is reliably avoided 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.

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 which is above the seawater pressure level can be set 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 intended. 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:

Fig. 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;

2: a circuit diagram of a pressure compensation device like FIG. 1, but with

- arranged in series - two diaphragm accumulators and one piston accumulator;

Fig. 3: Block diagram of the pressure compensation device according to Fig. 1 between

Seawater and (inner) fluid area;

Fig. 4: cross section through a further embodiment of the

Pressure compensation device with two diaphragm accumulators in an annulus; and

5: a perspective section through 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 accumulator 2a with a flexible wall area and a second accumulator 2b with a flexible wall area, both accumulators 2a and 2b being designed as bladder accumulators with a bladder 18 or 19 as a flexible wall area . The bladder 18 has a first opening 16 to the seawater area 7 and the bladder 19 has a second opening 17 to the fluid area 8. A piston accumulator 3 with a spring-loaded piston 5 is arranged between the first accumulator 2a and the second accumulator 2b. With 11 a space between the outer walls of the first bladder 18 and the second bladder 19 is designated, which is filled with a transmission medium. The pressure compensation device 1 is constructed such that the two accumulators 2a and 2b, the piston accumulator 3 and the intermediate space 11 are arranged in an annular pressure space (intermediate cavity 36, see FIG. 5) of a housing 27. 2 shows the basic diagram of a circuit diagram of a pressure compensation device 1 with - arranged and connected in series - two accumulators 2a, 2b with a flexible wall area 4 and a piston accumulator 3 with a displaceable piston 5. The accumulators 2a, 2b with flexible wall area 4 are explained in FIG. 1 using the example of two bladder accumulators and in FIG. 4 using the example of two membrane accumulators. Furthermore, the flexible wall 4 is explained in FIG. 1 using the example of an impenetrable bladder and in FIG. 4 using the example of an impenetrable membrane.

The first accumulator 2a (membrane accumulator) has a (interior) first interior 2.1 and a (interior) second interior 2.2, which are separated from one another by a flexible wall area 4, for example an elastic metal membrane (or a rubber bladder according to FIG. 1) are sealed against each other. The second accumulator 2b (membrane accumulator) is constructed in accordance with the first membrane accumulator 2a, a third interior 2.3 and a fourth interior 2.4 being present, which are separated by a flexible wall area 4. The piston accumulator 3 has a (interior) first interior 3.1 and an (interior) second interior 3.2, which are separated from each other by the displaceable piston 5 and sealed against one another by seals. 6 with a dash-dot line is a schematic dividing line, on the right side of which is the seawater area 7 and on the left side of which the (inner) fluid area 8 is located. A filter 38 for the seawater is arranged in front of the first reservoir 2a. The seawater filter can serve to prevent dirt particles from clogging the bore to the membrane 9.1. Furthermore, a displacement sensor 10 is assigned to the displaceable piston 5 of the piston accumulator 3. With 39 a container is designated.

FIG. 3 illustrates a block diagram of the pressure compensation device 1, for example also according to FIG. 1, between the seawater area 7 and the fluid area 8. The first interior 2.1 of the first reservoir 2a is located with the seawater region 7 and the fourth interior 2.4 of the second reservoir 2b with the fluid region 8 in connection. The second interior 2.2 of the diaphragm accumulator 2a and the first interior 3.1 of the piston accumulator 3 functionally form a common space 11. In terms of construction, the space 11 can be designed as a single space. The intermediate space 11 can also consist of two individual spaces, that is to say of the second interior 2.2 and the first Interior 3.1 exist, which are connected by a pipe or the like. 12 denotes a first boundary, for example a membrane 9.1, and 13 denotes a second boundary, for example a membrane 9.2. The two boundaries 12, 13 form a double security (redundancy) against ingress of sea water into the fluid region 8.

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

The system device downstream of the pressure compensation device 1 can be designed as a container-like module, for example container 39 (cf. FIG. 2), it being possible for a plurality of such modules to be deposited 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. Pressure compensation device 1 achieves pressure compensation between the interior of the container and the external environment (sea water region 7) in such a way that the liquid in the container is pressurized to the same pressure as prevails in the external environment. For this purpose, the pressure compensation device 1 has at least two separating surfaces or interfaces: a flexible separating element (membrane 9 or bladder), which is in contact with the sea water on one side, and a flexible separating element (membrane 9 or bladder), which is on the other side is acted upon by the liquid that is in the container. The intermediate space 11 is arranged between the two separating elements. The pressure compensation device 1 presented here has the particular advantage that sea water which has inadvertently penetrated through the membrane 9.1 does not get (directly) into the container, but rather remains blocked by the piston 5 in the intermediate space 11 and can be removed there. There is therefore a double security against ingress of sea water. Another additional safeguard is that the piston 5 of the piston accumulator 3 is acted upon by a compression spring 14, whereby the medium 25 is under a prestress. 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. In order to detect a leak in the piston accumulator 3, the displacement sensor 10 is assigned to the piston 5 and monitors the position of the piston 5.

4 illustrates a further embodiment of the pressure compensation device 1 with a first memory 2a and a second memory 2b, the two memories 2a and 2b being designed as membrane memories. As a flexible wall area 4, the first reservoir 2a has a first membrane 9.1 and the second reservoir 2b has a second membrane 9.2. The first flexible membrane 9.1 is supported on a first membrane plate 22, for example a rigid sheet, and the second flexible membrane 9.2 is supported on a membrane plate 23. In the first interior 2.1 there is a compression spring 15, one end of which is supported on the diaphragm plate 22 and the other end of which is supported in a recess 28 in the cover plate of the housing 27. There is a first medium 24 (sea water) in the first interior 2.1, a second medium 25 (for example transformer oil) in the intermediate space 11 and a third medium 26 (fluid, for example hydraulic oil) in the fourth interior 2.4.

5 shows, in perspective, in section the annular pressure space (between cavity 36) of a housing 27 as part of the pressure compensation device 1. There is an arrangement for a pressure compensation device 1 (for example according to FIGS. 1 and 4) in a common holding element. A hollow cylinder arrangement 29 - cut in half in FIG. 5 - has a hollow cylinder jacket 31 and a hollow cylinder interior 30. The housing 29 of the pressure compensation device 1 has the shape of the hollow cylinder arrangement 29. The second opening 17 is connected to 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 bore, is assigned to the seawater region 7 via a first connection 20, for example a pipe. The hollow cylinder arrangement 29 is composed of an outer (first) hollow cylinder 32 and an inner (second) hollow cylinder 33 arranged coaxially therewith, which have an outer hollow cylinder jacket 34 or an inner hollow cylinder jacket 35. Between the outer hollow cylinder jacket 34 and the inner hollow cylinder jacket 35, ie in the cylinder jacket 31 of the hollow cylinder-like housing 27 An annular intermediate cavity 36 is provided coaxially. 1, at least two accumulators 2a, 2b (bladder accumulators) and a piston accumulator 3 or, according to FIG. 4, two accumulators 2a, 2b (membrane accumulators) are arranged in the intermediate cavity 36. In a central opening of the hollow cylinder space 30, an actuating axis 37 shown in broken lines, for example a hydraulic cylinder (not shown) or a drive spindle (not shown) is arranged to save space.

Reference list

1 pressure compensation device

2 storage tanks with flexible wall area

2a first store with flexible wall area

2b second store with flexible wall area

2.1 first interior of 2a

2.2 second interior of 2a

2.3 third interior of 2b

2.4 fourth interior of 2b

3 piston accumulators

3.1 first interior of 3

3.2 second interior of 3

4 flexible wall area

5 pistons

6 dividing line

7 sea water area

8 fluid area

9 membrane

9.1 first membrane

9.2 second membrane

10 travel sensors

11 space

12 first limit

13 second limit

14 first compression spring

15 second compression spring

16 first opening

17 second opening

18 first bubble

19 second bubble

20 first connection

21 second connection

22 first membrane plate 23 second membrane plate

24 first medium

25 second medium

26 third medium

27 housing

28 recess

29 hollow cylinder arrangement

30 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 filters

39 containers

Claims

1. Pressure compensation device (1), set up for underwater applications, with which an interior of a container, which forms a fluid region (8), can be sealed off from the surrounding seawater region (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) are arranged in a row, the at least two stores (2; 2a, 2b) being arranged in an annular pressure chamber of a housing (27).

2. Pressure compensation device (1) according to claim 1, wherein the annular pressure chamber of the housing (27) is designed as a hollow cylinder arrangement (29) with two coaxially arranged hollow cylinders (32, 33), between which one

Intermediate cavity (36) is present.

3. Pressure compensation device (1) according to claim 2, wherein the at least two stores (2; 2a, 2b) with a flexible wall area (4) are arranged in the intermediate cavity (36).

4. 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.

5. 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.

6. 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).

7. 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).

8. 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).

9. Pressure compensation device (1) according to one of the preceding claims, wherein the piston (5) of the piston accumulator (3) is assigned a displacement sensor (10).

10. Pressure compensation device (1) according to one of the preceding claims, wherein between the at least two memories (2; 2a, 2b) with a flexible wall area (4)

Intermediate space (11) is formed, which is filled with a transmission medium.

11. Pressure compensation device (1) according to one of the preceding claims, it being designed such 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 (34). 35) are arranged opposite one another.

12. An 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 an actuating axis

(37) an electrical or hydraulic component is feasible.

13. Use of the pressure compensation device (1) according to one of the preceding claims for pressurizing at least one fluid-filled container (39) for a hydraulic actuating axis (37) of an electric motor, a pump or a cylinder compensation.