Hydraulic pressure accumulator

Abstract

2. Hydraulic pressure accumulator, at least comprising a storage housing (10) and a separating device which separates two fluid spaces (12) from each other in the storage housing (10) and has two connection points (16) on the storage housing (10) for the supply and / or discharge of a fluid attributable to the respective fluid space (12), characterized in that at least one connection point (16) is provided with a protective device (26) which at least partially covers the areas subject to corrosion at this connection point (16) and which remains on the pressure accumulator over its lifetime.

Description

[0001] The invention relates to a hydraulic pressure accumulator, at least consisting of an accumulator housing and a separating device which separates two fluid spaces from each other in the accumulator housing and has two connection points in the accumulator housing for the supply and / or discharge of a fluid attributable to the respective fluid space.

[0002] DE 10 2015 012 357 A1 discloses a hydraulic pressure accumulator or hydroaccumulator, in particular in the form of a membrane accumulator, comprising at least two housing parts of an accumulator housing in which a separating element, in particular in the form of an elastomeric separating membrane, separates two media or fluid spaces from each other, and with at least one media connection part connected to one of the housing parts along a weld seam, which forms a connection point in the accumulator housing and which engages at least partially in a receiving space in a nozzle-like manner, which is formed in one of the housing parts of the accumulator housing along a housing opening, wherein the adjacent wall surfaces of the housing part and the connection part in the receiving space are connected to each other by means of the weld seam.Because the weld seam forms a seat surrounding the connection part inside the housing opening of the storage housing, an optimally sealed and secure connection is ensured even under high stress, and the weld seam thus integrated into the storage housing is protected against corrosion.

[0003] Storage tank housings of this type are regularly subject to the Pressure Vessel Directive and are constructed from shell-like housing components made of common metallic materials, such as carbon steel, which are also susceptible to corrosion. Accordingly, at least the storage tank housing of the pressure accumulator requires external corrosion protection, which is typically achieved through painting or other protective coatings.If, particularly on the so-called gas side of the pressure accumulator, the corresponding connection point through which a working gas, usually nitrogen gas, can be introduced and extracted into one of the media or fluid chambers, is to be coated with a paint finish on the outer circumference in the same way as on the rest of the accumulator housing, then, at least during prolonged operation, paint will flake off in this area due to the attachment of standard filling and / or testing devices, which are typically screwed onto and off the external thread of the connection point using a fitting. In this way, the painted threads at the connection point are inevitably exposed and then subject to corrosion once again.In particular, such filling and / or testing devices serve to replenish the supply on the gas side of the storage tank using nitrogen charging devices if the supply has at least partially passed through the elastic separating membrane onto the liquid side of the tank. During filling, the gas pre-charge pressure can simultaneously be determined and readjusted using the aforementioned device.

[0004] In practice, galvanizing has become established as a further corrosion protection measure, at least on the gas connection side, providing long-lasting corrosion protection in the area of ​​gas connections. However, in addition to the increased manufacturing costs due to the coating process, galvanizing is now also considered an environmentally harmful measure.

[0005] Based on this prior art, the invention aims to further improve known solutions in such a way that the provision of corrosion-resistant pressure accumulators is made possible over a long period of time with low manufacturing costs and in an environmentally friendly manner. A hydraulic pressure accumulator with the features of claim 1 in its entirety achieves this objective.

[0006] According to the characterizing part of claim 1, at least one connection point is provided with a protective device that at least partially covers the areas at this connection point subject to corrosion and remains in place throughout the service life of the pressure accumulator. This means that the protective device is not removed from the gas connection point during normal operation of the pressure accumulator, even when a filling and / or testing device is connected externally, particularly to check the gas supply of the pressure accumulator and to replenish it as needed. During the manufacturing process of the pressure accumulator, the protective device is permanently attached to the gas connection point, thus allowing for the easy application of a protective coating to the outer circumference of the pressure accumulator housing for corrosion protection.It is understood that, within the scope of the invention, it is also possible to arrange such a protective device on the liquid side of the pressure accumulator with its associated connection point as needed, for example, for transport purposes. Preferably, the protective device is itself corrosion-resistant, at the latest after the application of a protective lacquer or other protective coating.

[0007] The hollow cylindrical and ring-shaped protective device can be additionally covered by a protective cap, which is removed when necessary, particularly to connect a filling and / or testing device to the pressure accumulator via the protective device. When in place, the protective cap covers one exposed end face of the ring body with its continuous central opening.

[0008] Thanks to the solution according to the invention, galvanizing of components of the accumulator housing is also unnecessary. This enables long-lasting, trouble-free operation of the pressure accumulator within the framework of complete hydraulic supply systems. Furthermore, the protective device can be used at connection points of all possible types of pressure accumulators, such as diaphragm accumulators, bladder accumulators, bellows accumulators, piston accumulators, etc.While it is generally possible to equip a hydraulic pressure accumulator with a housing made of high-strength plastic materials, such as carbon fibers, instead of conventional materials like carbon steels, stainless steels, and corrosion-resistant steels, such plastic designs prove to be very expensive, especially in high-pressure applications, and therefore only represent a solution for specific requirements, such as in the aerospace industry, where components must be both highly strong and lightweight. The corrosion-resistant construction of the pressure accumulator according to the invention allows it to be used even in corrosive environments, such as offshore wind turbines.

[0009] In a preferred embodiment of the hydraulic pressure accumulator according to the invention, the connection point consists of a hollow cylindrical connection nozzle that can be connected, and in particular screwed, to the protective device along a connecting section, in particular a threaded section. Preferably, the connection point, particularly on the gas side of the pressure accumulator, is a one-piece, nozzle-like component of the accumulator housing, and is specifically arranged projecting from the circumference of an upper accumulator housing part in its pole region. In this respect, the otherwise customary weld between the connection nozzle and the upper accumulator housing part is unnecessary. However, this does not apply when forged parts are used. The connection nozzle, which protrudes flush from the upper accumulator housing part, provides a good point of attachment for the releasable connection of the protective device to the connection nozzle.However, it is also possible to create an inseparable, permanent connection between the protective device and the connection fitting, for example by welding or crimping.

[0010] In a further preferred embodiment of the hydraulic pressure accumulator, the connection nozzle with the protective device has a central opening for the engagement of a releasable sealing screw. In a closed position, this screw engages the connection nozzle and hermetically seals the associated fluid chamber from the environment. This chamber preferably serves to hold a working gas, such as nitrogen gas. It is also preferable that the sealing screw is secured against unintentional leakage into the environment by a locking mechanism inside the connection nozzle.

[0011] In a further particularly preferred embodiment of the hydraulic pressure accumulator according to the invention, the protective device is formed from a double-sided ring body which, fixed to the connection nozzle, encompasses the connection nozzle with a predefinable length in the axial direction such that a head portion of the sealing screw, which projects beyond the connection nozzle in its closed position, is at least partially enclosed with a predefinable radial distance. In this way, the sealing screw is also protected from unintentional external actuation by the protective device. Preferably, one free end of the ring body is flush or substantially flush with the free head face of the head portion of the sealing screw.

[0012] In a further preferred embodiment of the hydraulic pressure accumulator according to the invention, the other free end of the ring body rests on the defined rim on the top of the accumulator housing, preferably along a sealing line or sealing surface formed on one side by a projection at the other free end of the ring body and on the other side by a flat surface area of ​​the top of the accumulator housing that includes the connection nozzle for the gaseous fluid. In this way, the protective device also seals the connection nozzle and its connecting section from the environment at the bottom, so that no corrosive media, including air, can reach either the connection nozzle or the sealing screw.For this purpose, the ring body preferably has a reduction in diameter facing towards the head part of the sealing screw, which covers the threaded section of the connecting piece to the outside.

[0013] In a further preferred embodiment of the hydraulic pressure accumulator according to the invention, the ring body has a diameter widening in the direction away from the threaded section, which carries an annular groove for receiving a sealing device, in particular in the form of an O-ring. Preferably by means of a protective cap that can be screwed onto an external thread of the ring body, the ring body is covered with a closed cap section, and in the defined state of the protective cap, it comes into sealed contact with the sealing device of the ring body. Thus, the transition point between the ring body of the protective device and the protective cap is hermetically sealed from the environment.

[0014] In a further preferred embodiment of the hydraulic pressure accumulator, the head section is sealed at a transition point to the screw thread of the sealing screw against the connection port by means of an additional sealing device. This additional sealing device advantageously seals the interior of the upper accumulator housing section, with its gas side, against the environment in the area of ​​engagement of the sealing screw.

[0015] In a further preferred embodiment of the hydraulic pressure accumulator according to the invention, the surface of the accumulator housing is protected against corrosion by means of a corrosion protection coating, such as a paint or a coating, which preferably also includes the additional connection point for fluid, such as a hydraulic medium. When such corrosion protection is applied by spraying, the nozzle-like connection point is completely covered by the protective device.

[0016] In a further preferred embodiment of the hydraulic pressure accumulator according to the invention, the ring body is made of corrosion-resistant material, such as stainless steel, and is open on opposite sides, featuring a diameter reduction on one side and a diameter expansion on the other. It also has an internal thread that extends from the diameter reduction to the free end of the ring body. In this respect, the ring body, and thus the protective device, can be provided with a coating, such as a paint finish, similar to the outer surface of the accumulator housing.

[0017] The pressure accumulator according to the invention will now be explained in more detail with reference to an embodiment shown in the drawing. The drawing is a simplified, not to-scale representation of the... Fig. 1 partly in view, partly in the form of a sectional view, the upper connection point of a membrane storage tank as a whole; Fig. 2 a partial longitudinal section view through the upper part of a storage housing part after the Fig. 1 with attached protective device and protective cap; and Fig. 3. A top view of the pressure accumulator after the Fig. 2, shown in the upper half with protective cap and in the lower half without.

[0018] The Fig. Figure 1 shows a hydraulic pressure accumulator as a whole, here in the form of a so-called diaphragm accumulator. The pressure accumulator has a storage housing 10 and a separating device arranged therein (not shown), for example in the form of an elastomeric separating membrane, which separates two fluid chambers 12, 14 from each other in the storage housing 10, which in Fig. 1 are shown only in outline. The storage housing 10 has two connection points 16, 18 for the supply and / or discharge of a fluid attributable to the respective fluid chamber 12, 14. In the direction of view of the Fig. Figure 1, which depicts an operating position of the pressure accumulator, shows the upper fluid chamber 12 as the so-called gas side of the pressure accumulator, which is separated from a liquid chamber, the further fluid chamber 14, by means of the separating device or separating membrane in a media-tight manner. While a working gas, such as nitrogen, is regularly used on the gas side of the pressure accumulator, the pressure accumulator can regularly be filled with a hydraulic medium, such as hydraulic oil, on its liquid side, and in this respect the pressure accumulator is described in the Fig. 1. The pressure accumulator is connected via its lower second connection point 18 to a pressure supply circuit (not shown) for the purpose of actuating hydraulic working cylinders of a working device (not shown). The design and use of such pressure accumulators is common and is illustrated by way of example in DE 10 2015 012 357 A1. It is understood that, within the scope of the invention, the pressure accumulator can also perform a different type of fluid separation for other applications and that the fluids used can change accordingly. Furthermore, the pressure accumulator is designed according to the Fig. 1, as is customary in the prior art, provided only with a protective cap 19, preferably made of plastic materials. In this respect, the invention is described in relation to the Fig. 2 and Fig. 3 explained in more detail.

[0019] Unlike known pressure storage or diaphragm storage solutions, the two connection points 16, 18 are integral parts of the storage housing 10 and therefore do not need to be welded to it separately. Furthermore, in the present case, the storage housing 10 consists, in the usual manner, of two shell parts in the form of an upper and a lower storage housing part 20 and 22, respectively, which are permanently welded together along a circumferential weld seam 24. The construction of the storage housing 10 from individual shell or housing parts 20, 22, which are welded together at their ends, is therefore common practice, and will not be discussed in further detail here. In any case, the housing parts 20, 22 with their connection points 16, 18 can be produced by machining or, preferably, by forging or deep drawing.

[0020] At least the upper gas-side connection point 16 is provided with a protective device 26, preferably corrosion-resistant, which at least partially, preferably completely, covers the areas at this connection point 16 that are subject to corrosion. The protective device 26 is designed to be corrosion-resistant insofar as it is constructed of stainless steel materials, consists of plastic materials, or at least bears a coating on the metal that is exposed to the environment, in particular in the form of a protective lacquer 27 or other protective coating, which is in the Fig. 1 is represented by dashed lines.

[0021] As shown, each connection point 16, 18 consists of a hollow cylindrical connection piece 28, 30, wherein the upper connection piece 28 can be connected, in particular screwed, to the protective device 26 along a connecting section 32 in the form of a threaded section. For this purpose, the upwardly projecting connection piece 28 has an external thread 34 onto which the hollow cylindrical protective device 26 can be screwed with its internal thread 36 in a releasable manner, wherein the Fig. Figure 2 shows the fully installed position of the protective device 26. However, it is also possible (not shown) to make the connection permanent, for example by means of a welded or pressed connection.

[0022] What next? Fig. As shown in Figure 2, the connecting piece 28, together with the protective device 26, has a continuous central opening 38 for the engagement of a releasable locking screw 40, which is located in a Fig. 1 and Fig. In the closed position shown in Figure 2, the screw is engaged with the connecting nozzle 28 and hermetically seals the associated inner fluid chamber 12 from the environment. This chamber preferably serves to hold a working gas, such as nitrogen gas. A corresponding sealing screw 40 with a locking element to prevent unintentional loosening is shown in DE 10 2007 032 207 A1.According to the teaching of this patent, a curved, longitudinally extending notch (not shown) is provided on the shaft 42 of the sealing screw 40. This notch is formed as a narrow interruption of the external thread 44 present in this area. When the sealing screw 40 is open, this notch extends beyond a threaded section 45 of a threaded bore 46 in the connecting nozzle 28, thus enabling the successive release of a media passage between the fluid chamber 12 and a filling and / or testing device to be connected. After removing the protective cap 19, the filling and / or testing device can be screwed onto an external thread 74 of the protective device 26. The protective cap 19 can be secured via a threaded section on the outer circumference of the protective device 26, and the corresponding external thread 74 of the protective device 26 serves as a standard part for screwing on the filling and / or testing device.In this way, the protective device 26 no longer needs to be removed during the entire service life of the hydraulic accumulator and can thus continuously fulfill its protective function. Such filling and / or testing devices are commercially available and can be obtained from the patent holder under the designation FPU (see prospectus HYDAC International Filling and Testing Device FPU / DE 3.501.31 / 02.20).

[0023] The protective device 26 is formed from a solid ring body 48, which is fixed to the upper connecting piece 28, in particular by screwing, pressing, or welding. Viewed axially, it overlaps the connecting piece 28 with a predefinable length such that a head part 50 of the locking screw 40, which projects beyond the connecting piece 28 in its closed position, is encompassed by a predefinable radial distance 52. The head part 50 has, in the usual manner (not shown), a recess on its inner side, such as an internal hexagon socket, for the engagement of an actuating tool (not shown), such as an Allen key. A circumferential annular collar 54 is present between the head part 50 and the shaft 42 with the external thread 44, forming a constriction.The one free upper end of the ring body 48 is essentially flush with the free head side of the head part 50 of the locking screw 40, as shown in the illustration. Fig. 2 the head part 50 may also have a slight protrusion above the top of the ring body 48 in the fixed position of the locking screw 40.

[0024] The other, lower free end of the ring body 48 sits on the upper surface 56 of the storage housing 10. For this purpose, the corresponding upper storage housing part 20 has a flat annular surface 58, coaxial with the hollow cylindrical connection stub 28. Furthermore, the ring body 48 has a projection 60 at its lower free end in the form of a circumferential cam track, which, with the annular surface 58 or the flat surface area of ​​the upper surface 56 of the storage housing 10, forms a linear sealing surface 62 when the protective device 26 is in the fixed position on the connection stub 28. In this way, a fluid-tight, corrosion-resistant transition point is also created at the base of the protective device 26 and the storage housing 10. The sealing force results from the tightening torque with which the protective device 26 is fixed to the upper connection stub 28 via the threaded connection 32.

[0025] The ring body 48 has a diameter reduction 64 facing the head 50 of the sealing screw 40, which protectively covers the threaded connection section 32 towards the outside. In this respect, the circular cylindrical diameter reduction 64 encompasses the radial distance 52. On the opposite lower side, the ring body 48 has a diameter expansion 66 in the direction away from the threaded section 32, which carries a circumferential annular groove 68 for receiving a sealing device, in the form of a conventional O-ring 70. The protective cap 19, which forms the threaded section with an internal thread 72 onto the external thread 74 ( Fig. 3) the ring body 48 is screwable, the ring body 48 is as shown in the illustration according to the Fig. 2 covered and thus in the fixed state of the protective cap 19 in a sealed manner in contact with the sealing device in the form of the O-ring 70. The corresponding external thread 74 is only in the Fig. Figure 3 partially shows that on opposite sides, an identical flattened section 76 penetrates the protective device 26. This flattened section serves as a guide for a wrench (not shown) to tighten and loosen the protective device 26 on the upper part of the storage housing 20 along the connecting piece 28. The distance between the two flattened sections 76 determines the wrench size for the respective operating tool. Furthermore, the corresponding external thread 74 of the ring body 48, as already explained, serves for attaching the filling and / or testing device by screwing it on.

[0026] The head 50 of the sealing screw 40 is in turn sealed at a transition point in the form of the ring collar 54 to the shaft 42 with the screw or external thread 44 against the connecting nozzle 28 by means of a further sealing device 78 in the form of a flat gasket or other sealing ring. Thus, in the fixed state of the sealing screw 40 as shown in the illustration, Fig. 2. The fluid chamber 12 is hermetically sealed from the environment. The in Fig. The connection point 16 shown in section 2 can now be coated with a protective coating 27, as shown in Fig.As shown in Figure 1, the protective device 26 is coated. Thanks to the protective device 26 in its fixed position on the storage housing 10, no paint can reach the threaded connection 32 on the outer circumference of the connection nozzle 28, so that the connection 32 remains free of paint particles in all cases. Even after the protective cap 19 is removed from the safety device 26, no corrosive media can reach the connection 32. Sealing is achieved at the bottom via the sealing surface 62 between the protective device 26 and the storage housing 10, and the opening or free space formed by the radial distance 52 is effectively covered by the protective cap 19. Thus, corrosion protection is achieved in the connection area of ​​the filling and / or testing device, even during prolonged operation of the pressure or hydraulic accumulator. This has no equivalent in the prior art.This also applies if the associated connecting piece 28 is welded to the other reservoir components of the hydraulic accumulator in a different configuration along a linear connection point (not shown). Furthermore, the protective device 26 need not be exclusively bolted to the associated connecting piece 28 as shown; rather, the protective device 26 can be fixed by alternative joining techniques, such as pressing, welding, etc.

[0027] Preferably, the ring body 48 itself is made of corrosion-resistant material, such as stainless steel, and the protective cap 19 shown can be made of a suitable plastic material. Thus, robust, continuous corrosion protection is locally present at the so-called gas valve of the pressure accumulator. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 012 357 A1 [0002, 0018] DE 10 2007 032 207 A1

[0022]

Claims

[1] Hydraulic pressure accumulator, at least consisting of an accumulator housing (10) and a separating device which separates two fluid spaces (12, 14) from each other in the accumulator housing (10) and is connected to the accumulator housing (10) with two connection points (16, 18) for the supply and / or discharge of a fluid attributable to the respective fluid space (12, 14), characterized by , that at least one connection point (16) is provided with a protective device (26) which at least partially covers the areas at this connection point (16) that are subject to corrosion, and which remains on the pressure accumulator over its lifetime. [2] Hydraulic pressure accumulator according to claim 1, characterized by , that the connection point (16, 18) consists of a hollow cylindrical connection stub (28, 30) which can be connected, in particular screwed, to the protective device (26) along a connecting section (32), in particular a threaded section. [3] Hydraulic pressure accumulator according to claim 1 or 2, characterized by , that the connecting nozzle (28) with the protective device (26) has a central opening (38) for the engagement of a releasable sealing screw (40), which in a closed position engages with the connecting nozzle (28) and hermetically seals the associated fluid space (12) from the environment, which preferably serves to hold a working gas, such as nitrogen gas. [4] Hydraulic pressure accumulator according to one of the preceding claims, characterized by , that the protective device (26) is formed from a ring body (48) which is fixed to the connecting piece (28), preferably viewed in the axial direction, overlaps the connecting piece (28) with a predefinable length such that a head part (50) of the locking screw (40), which projects beyond the connecting piece (28) in its closed position, is at least partially encompassed with a predefinable radial distance (52). [5] Hydraulic pressure accumulator according to one of the preceding claims, characterized by that one free end of the ring body (48) is flush or substantially flush with the free head side of the head part (50) of the locking screw (40). [6] Hydraulic pressure accumulator according to one of the preceding claims, characterized by , that the other free end of the ring body (48) sits on the top (56) of the storage housing (10), preferably along a sealing line or sealing surface (62) formed on one side by a projection (60) at the other free end of the ring body (48) and on the other side by a flat surface area (58) of the top (56) of the storage housing (10), which includes the connection nozzle (16) for the gaseous fluid. [7] Hydraulic pressure accumulator according to one of the preceding claims, characterized by, that the ring body (48) has a diameter reduction (64) facing towards the head part (50) of the locking screw (40), which covers the thread section (32) to the outside. [8] Hydraulic pressure accumulator according to one of the preceding claims, characterized by , that the ring body (48) has a diameter expansion (66) in the direction away from the threaded section (32) which carries an annular groove (68) for receiving a sealing device, in particular in the form of an O-sealing ring (70). [9] Hydraulic pressure accumulator according to one of the preceding claims, characterized by , that by means of a protective cap (19) which can be screwed onto an external thread (74) of the ring body (48), the ring body (48) is covered and that in the specified state of the protective cap (19) it comes into sealed contact with the sealing device (70) of the ring body (48). [10] Hydraulic pressure accumulator according to one of the preceding claims, characterized by , that the head part (50) is sealed at a transition point (54) to the screw thread (44) of the sealing screw (40) opposite the connecting nozzle (28) by means of a further sealing device (78). [11] Hydraulic pressure accumulator according to one of the preceding claims, characterized by , that the surface of the storage housing (10) is protected against corrosion by means of corrosion protection, such as a paint (27) or a coating, which preferably includes the further connection point (18) for fluid, such as a hydraulic medium. [12] Hydraulic pressure accumulator according to one of the preceding claims, characterized by, that the ring body (48) of the protective device (26) is made of corrosion-resistant material, such as stainless steel, which is provided on opposite sides with a diameter reduction (64) on one side and a diameter expansion (66) on the other and has an internal thread (36) which opens outside the diameter reduction (64) at the free end of the ring body (48). [13] Hydraulic pressure accumulator according to one of the preceding claims, characterized by , that the ring body (48) is additionally or alternatively corrosion-resistant by coating.

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