Hydraulic accumulator

Abstract

The invention relates to a hydraulic accumulator, in particular a diaphragm accumulator, at least consisting of two housing parts (10, 12) which are held against one another by means of a fixing ring connection (14) so as to form an accumulator housing (16), and having a separating element (20) which is arranged at least partially movably within the accumulator housing (16) and which separates two fluid chambers (24, 26) from one another, characterised in that, in the fixed state of a fixing ring (32) of the fixing ring connection (14), said fixing ring is completely covered towards the environment (34) by the housing parts (10, 12).

Description

[0001] Hydro storage

[0002] The invention relates to a hydraulic accumulator, in particular a membrane accumulator, comprising at least two housing parts which are held together by means of a locking ring connection to produce an accumulator housing and with a separating element arranged at least partially movable within the accumulator housing, which separates two fluid spaces from each other.

[0003] DE 10 2015 012 357 A1 discloses a hydraulic accumulator, particularly 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 a separating membrane, separates two media compartments from one another, and with at least one media connection part connected to one of the housing parts along a weld seam, wherein the connection part engages at least partially in a receiving compartment formed in one of the housing parts along a housing opening, and wherein the adjacent wall surfaces of the housing part and the connection part are connected to each other by means of the weld seam in the receiving compartment. The two housing parts are joined end-to-end along a seam by a further weld seam, which can be produced by electron beam welding or laser beam welding without welding filler materials.To prevent unwanted welding spatter from reaching the inside of the storage housing with the sensitive elastomeric separating membrane during the welding process, the weld seam to be produced is fully covered on the inner circumference by an annular projection of one of the two housing parts.

[0004] DE 10 2014 005 51 1 A1 discloses a storage device, in particular in the form of a hydraulic accumulator, with a storage housing consisting of at least two housing parts which at least partially define a working space in the storage housing, in which a separating device is movably guided to separate two media spaces from each other and is held in a fixed position in the storage housing at a predetermined fixing point by means of a holding device, wherein the holding device applies the separating device to at least one of the housing parts in a contacting manner with a defined contact force while maintaining a constant or substantially constant wall thickness in the area of ​​the fixing point.

[0005] During assembly, the two shell-like housing parts are first partially placed inside one another, and the free edge of the larger-diameter housing part is folded over onto a defined top surface of the smaller-diameter housing part using a crimping or flanging process with a predefined crimping force. In this way, the two housing parts are permanently and fluid-tightly joined by a flanging process as an alternative to welding.

[0006] DE 10 201 1 1 17 752 A1 discloses a hydraulic accumulator in the form of a bellows accumulator, comprising an accumulator housing in which the bellows, having a predefinable number of folds, forms a movable separating element between the gas side and the fluid side. A spacer device is provided, which is arranged within the accumulator housing and is in fluid communication with the interior of the bellows, forming an additional media space, or is adjacent to the bellows. Furthermore, the bellows is received in the accumulator housing, and a bottom end of the housing forms a stop that limits the movement of the bellows to a stroke corresponding to a predefinable maximum volume consisting of the volume inside the bellows and an additional volume of the pot-shaped accumulator housing.The corresponding housing end part is fixed at its free end, pointing towards the environment, to the inside of the storage housing in a releasable manner by means of a locking ring connection, the associated locking ring consisting of a snap ring which is accessible from the outside and therefore not further secured, allowing the unintentional release of the interior of the storage housing with the bellows or bellows.

[0007] Based on this state of the art, the invention is based on the problem of improving known solutions while retaining their other features.

[0008] The advantages are further improved, in particular by connecting two housing parts of a storage tank housing in a reliable and cost-effective manner for the purpose of easily assembling a hydraulic accumulator. A hydraulic accumulator with the features of claim 1 as a whole solves this problem.

[0009] Because, according to the characterizing part of claim 1, in the fixed state of a locking ring connection, the locking ring is completely covered by the housing parts on the exterior side, the locking ring connection is an integral part of the storage housing assembly. This prevents the connection from unintentionally loosening from the outside, thus increasing operational reliability, especially in cases of high fluid or media pressure within the storage housing. The locking ring connection is easy to assemble. The locking ring, preferably designed as a slotted spring washer, is readily available on the market in a wide variety of designs, allowing the aforementioned connection solution to be obtained at minimal cost.In particular, such fixing rings are standardized (for example DIN 9926:2016-1 1 ), which facilitates their use in hydraulic storage designs.

[0010] Since the locking ring is shielded from the environment in a fixed state by the aforementioned housing parts, it is largely protected from corrosion, even if the hydraulic accumulator is used in aggressive environments, such as those with salty or chemically contaminated ambient air.

[0011] In a preferred embodiment of the hydraulic accumulator according to the invention, one housing part has a fluid connection, particularly in the form of a gas connection such as nitrogen gas, and the other housing part has a further fluid connection, particularly in the form of a liquid connection for a hydraulic medium such as hydraulic oil. Such hydraulic accumulators are regularly used in hydraulic systems, among other things, to store specific volumes of pressurized fluids and return them to the system as needed. Hydraulic systems with hydropneumatic accumulators are particularly common, which, as in the present case, are preferably equipped with a separating device designed as a diaphragm. The flexible, elastically compliant diaphragm separates a liquid chamber as the working chamber from a gas chamber as a further working chamber.The membrane effectively decouples the gas and liquid chambers. The liquid chamber is connected to a hydraulic circuit of the hydraulic system via the fluid connection of the accumulator housing. As the pressure in the hydraulic circuit increases, the accumulator absorbs hydraulic fluid, compressing the working gas. When the pressure decreases, the previously compressed working gas expands, displacing the liquid back into the hydraulic circuit. In this way, such accumulators can serve as energy storage devices for recuperation in technical systems.

[0012] In a further preferred embodiment of the hydraulic accumulator according to the invention, the two housing parts are at least partially nested to form the accumulator housing, in particular the housing part with the gas connection is at least partially nested within the housing part with the liquid connection. In this respect, the two housing parts are aligned concentrically to each other along the longitudinal axis of the accumulator housing, which is advantageous during assembly.

[0013] In a further particularly preferred embodiment of the hydraulic accumulator according to the invention, the two facing housing parts, starting from their respective free end faces, define an edge region that forms an overlapping area along which adjacent wall sections of both housing parts are in contact with each other. Due to this mutual wall contact, the locking ring connection is fully protected from the outside environment, as a type of seal is created by the housing parts of the accumulator housing.

[0014] In a further preferred embodiment of the hydraulic accumulator according to the invention, the housing part with one fluid connection has an annular recess in the form of a receiving groove into which the locking ring can be inserted, spread open, before being engaged. Preferably, the other housing part with the fluid connection has a further annular recess in the form of another receiving groove into which the slotted, spring-loaded locking ring engages as soon as both recesses are aligned during assembly, i.e., when the two housing parts are centered within the overlap area in their final position.

[0015] It is preferably provided in the fixed state of the locking ring that, under spring-elastic preload, it engages with an outer circumferential part in the further recess in the further housing part and remains with another inner circumferential part in the recess of one housing part.

[0016] In a further preferred embodiment of the hydraulic accumulator according to the invention, it is provided that in the assembled state the two recesses of both housing parts have annular and conical tapered slopes in the direction of a receptacle for the separating element, in particular in the form of a separating membrane, in the manner of approach or fixing slopes, during assembly.

[0017] For reliable installation of the locking ring, it is preferably further provided that the annular receptacle for the separating element is formed by the inner surfaces of both housing parts of the storage housing, and that the recess for the locking ring in one housing part has a shallower depth than the adjacent receptacle for the separating element. This results in only a slight weakening of the wall material in one housing part, which contributes to a pressure-resistant construction. The invention also relates to a method for creating a locking ring connection, wherein, with the aid of an assembly tool, when fixing one housing part together with the locking ring, the other housing part is pushed axially onto the first housing part from its free edge until the locking ring snaps into an adjacent recess of the other housing part due to its inherent elasticity.

[0018] Thanks to the assembly aid, which can be used for both mounting and dismounting the storage housing, very large quantities of hydraulic accumulators can be obtained in a cost-effective and production-technically traceable manner, especially for low-pressure and medium-pressure applications, which is extremely economical, so that the hydraulic accumulator can also be designed in the manner of a disposable accumulator.

[0019] The hydraulic accumulator according to the invention, along with the method described, will now be explained in more detail using an exemplary embodiment as shown in the drawing. The drawing is a general, not to scale, representation of the...

[0020] Fig. 1 shows, in the form of a longitudinal section, the essential components of the hydraulic accumulator as a whole;

[0021] Fig. 2 shows, in the form of a longitudinal section view, the essential components of an assembly device for the hydraulic accumulator according to Fig. 1; and

[0022] Fig. 3 shows an enlarged section of the frame labeled X in Fig. 2. Fig. 1 shows a hydraulic accumulator in the form of a diaphragm accumulator as a whole. The hydraulic accumulator, or diaphragm accumulator, has two housing parts 10, 12, which are held together by means of a locking ring connection 14 to form an accumulator housing 16. Inside 18 of the accumulator housing 16, a separating element 20 in the form of an elastomeric separating membrane 22 is arranged in the usual manner and is at least partially movable. The separating element 20, or separating membrane 22, separates two fluid chambers 24, 26 within the accumulator housing 16. For this purpose, the separating membrane 22 is shaped like a dome, pot- or shell-shaped, and is fixed within the accumulator housing 16 at its free circumferential edge 28, which is provided with a thickening.Furthermore, a closure element 30 is buttoned into the bottom of the separating membrane 22 for improved sealing of the fluid chamber 26 of the accumulator housing 16 against a hydraulic circuit (not shown) to which the accumulator is regularly connected. This design is common, so it will not be discussed in further detail here.

[0023] As can be further seen from Fig. 1, in the fixed state of a locking ring 32 of the locking ring connection 14, it is completely covered by the housing parts 10, 12 towards the surroundings 34. The locking ring 32 is designed as a slotted spring ring in the manner of a snap ring, and the slot 36 provided in the ring body is shown on the left when viewed from Fig. 1, where the slot 36 provides an end-face view of the ring body of the locking ring 32, which is provided with a predefinable ring diameter. In particular, such a locking ring 32 is a standardized snap ring made of elastic spring steel material.

[0024] One upper housing part 10 has a fluid connection 38, in particular in the form of a gas connection for a working gas, such as nitrogen gas. The fluid connection 38 has a through central opening which is closed in the usual manner by a sealing screw 40. The fluid connection 38 and the sealing screw 40 are covered by a screw-on protective cover 42, preferably made of plastic material, at least during transport.

[0025] The other, underlying housing part 12 has a further fluid connection 44, in particular in the form of a liquid connection for a hydraulic medium, such as hydraulic oil. This design is also common in hydraulic accumulators, especially diaphragm accumulators, so it will not be discussed in further detail here. The two housing parts 10, 12 are at least partially nested to form the accumulator housing 16; in particular, housing part 10 with the gas connection is at least partially inserted into housing part 12 with the liquid connection. The two facing housing parts 10, 12, starting from their respective free end faces, each define an edge region, which together form an overlap region 46, along which adjacent wall sections 48, 50 of both housing parts 10, 12 are in contact with each other.

[0026] Furthermore, the housing part 10 with the fluid connection 38 has an annular circumferential recess 52 in the form of a receiving groove, into which the locking ring 32 can be fully opened and inserted before the two housing parts 10, 12 are engaged together. Further details can be seen in particular in the illustration according to Fig. 3, which shows an enlarged view of the box-shaped cutout designated X in Fig. 2.

[0027] The other housing part 12, with the additional fluid connection 44, has a further annular recess 54 in the form of a further receiving groove, into which the spring-loaded locking ring 32, provided with the slot 36, engages as soon as both recesses 52, 54 are aligned, as shown in Figures 1 to 3. In the locked position, the locking ring 32, under spring preload, engages with its outer circumferential portion in the further recess 54 in the other housing part 12 in the operating position shown in Figure 1, while its other inner circumferential portion remains in the opposite recess 52 of the first housing part 10.

[0028] As can be seen further in Fig. 3, the two recesses 52, 54 have annular and conical chamfers 58, 60 in the corresponding wall sections of housing part 10 and housing part 12, respectively, extending towards a chamber-shaped receptacle 56 for the circumferential edge 28 of the separating element 20. These chamfers 58, 60 are designed as insertion and removal aids to facilitate the assembly of the two housing parts 10, 12. As can be seen further from Fig. 3, the inclined plane 60 in the wall part 50 of the housing part 12 has a greater inclination than the opposite inclined plane 58 in the wall part 48 of the housing part 10. As can be seen further, particularly from Fig. 3, the annular receptacle 56 for the separating element 20 is deeper than the adjacent recess 52 in the housing part 10 for the retaining ring 32.

[0029] Figure 2 shows in detail an assembly aid 62 for assembling the two housing parts 10, 12 to form the storage housing 16. The assembly aid 62 has a support 64 into whose annular receptacle a head-end region of one housing part 10 with the fluid connection 38 can be inserted or placed. A retaining plate 66 is inserted centrally into the support 64 and secured by a screw connection 68, of which only a single engagement screw is shown in Figure 2. The retaining plate 66 has a centrally projecting upward retaining pin 70, which engages with a predefinable clearance in the threaded receptacle that is otherwise provided for securing the sealing screw 40. In this way, one housing part 10 is supported by the support 64 of the assembly aid 62 with a predefinable clearance.

[0030] The assembly aid 62 further comprises an annular actuating plunger 72, which, viewed in the direction shown in Fig. 2, is vertically movable up and down in opposite directions. The actuating plunger 72 has an annularly recessed receiving flange 74 on its free inner side, onto which the further housing part 12 is placed flush with its free end face. The receiving flange 74 has a circumferential control edge 76 on its inner circumference, which is formed towards its free, inner end by more or less pointed wall sections of the actuating plunger 72, thus creating a kind of edge-shaped projection or pressure edge.

[0031] During assembly, the circumferential edge 28 of the separating element 20 is already permanently inserted or pressed into the corresponding receptacle 56 in the housing part 10, and the spread-open locking ring 32 is in its fully opened state in the annular recess 52 of the housing part 10 and thus projects beyond the corresponding adjacent wall part 48 of the housing part 10 with a predefinable overhang, as well as beyond the free edge of the recess 52. If the actuating plunger 72 is now moved from an upper starting position to the position shown in the Fig.In the assembly position shown in Fig. 2, moving from top to bottom with the housing part 12 in place, the control edge 76, as it passes over the recess 52, compresses the snap ring or locking ring 32. This is easily possible due to its slot 36, so that the subsequent edge area of ​​the further housing part 12, forming the overlap area 46, passes over the locking ring 32 and simultaneously pre-tensions it by compression. When, as shown in Fig. 3, both recesses 52, 54 then align, the locking ring 32, due to its pre-tension, retracts and rests with a defined pre-tension force on the outer circumferential side against the inner circumferential side of the further recess 54 in the housing part 12, which follows its contour. The chamfers 58, 60 support the sliding or moving process of the locking ring 32 into its respective pre-tensioned or locked position.

[0032] Once the two storage housing parts 10 and 12 are placed next to each other and locked together via the locking ring 32, forming the storage housing 16 with the separating element 20 in place, the finished storage unit can be easily removed. The inclined surface 58 prevents disassembly. It ensures that the locking ring 32 is always pressed into the recess 54 under tension or internal pressure. Otherwise, the housing 16 could unintentionally fly apart under the corresponding internal pressure.

[0033] The hydraulic accumulators or pressure accumulators discussed here consist preferably of extruded or forged blanks, particularly with regard to the housing parts 10, 12, in order to ensure the most cost-effective accumulator housing design possible. In this case, the primary focus is on small accumulator volumes, although the design principle shown is not limited to this. The connection solution according to the invention, in its practical embodiment, is a type of snap-ring connection to connect the two housing parts 10, 12, as the accumulator upper and lower parts respectively, as efficiently as possible in a single pressing or joining operation during the membrane insertion process. In this way, only low investment costs are necessary for the production of the accumulator structure, since only a press, i.e., the assembly aid 62, with a comparatively low pressing force via the actuating plunger 72 is required to join the pressure-bearing parts.In contrast to the forming design, as shown, for example, in DE 10 2014 005 51 1 A1, the use of the split or locking ring 36 results in a lower weight for the overall storage solution due to the reduced material usage. The design described above therefore represents a low-cost alternative to conventional membrane storage systems in the prior art.

[0034] The connection solution according to the invention can be used for any material combination; for example, the two housing parts 10, 12 can be made of steel, aluminum, or titanium. In any case, the solution according to the invention eliminates the need for production-intensive welding processes. Furthermore, conventional membrane storage structures, whether welded or formed, are generally manufactured in two process steps; the membrane insertion process is typically followed by welding or forming in a second, separate process step, which can be time-consuming, especially in the case of welding. The connection solution described above avoids this. This has no equivalent in the prior art.

Claims

Patent claims 1. Hydraulic accumulator, in particular a diaphragm accumulator, comprising at least two housing parts (10, 12) which are held together by means of a locking ring connection (14) to produce an accumulator housing (16) and with a separating element (20) arranged at least partially movably within the accumulator housing (16) which separates two fluid spaces (24, 26) from each other, characterized in that in the fixed state of a locking ring (32) of the locking ring connection (14) this is completely covered by the housing parts (10, 12) towards the environment (34).

2. Hydraulic accumulator according to claim 1, characterized in that one housing part (10) has a fluid connection (38), in particular in the form of a gas connection for a working gas, such as nitrogen gas, and that the other housing part (12) has a further fluid connection (44), in particular in the form of a liquid connection for a hydraulic medium, such as hydraulic oil.

3. Hydraulic accumulator according to claim 1 or 2, characterized in that the two housing parts (10, 12) are at least partially inserted into one another to form the accumulator housing (16), in particular the housing part (10) with the gas connection is at least partially inserted into the housing part (12) with the liquid connection.

4. Hydraulic accumulator according to one of the preceding claims, characterized in that the two mutually facing housing parts (10, 12), starting from their respective free end faces, define an edge area which together form an overlap area (46) along which adjacent wall parts (48, 50) of both housing parts (10, 12) are at least partially in contact with each other.

5. Hydraulic accumulator according to one of the preceding claims, characterized in that the housing part (10) with the fluid connection (38) has an annular recess (52) in the form of a receiving groove into which the locking ring (32) can be inserted with clearance before locking.

6. Hydraulic accumulator according to one of the preceding claims, characterized in that the other housing part (12) with the fluid connection has a further annular recess (54) in the form of a further receiving groove, into which the slotted, spring-loaded retaining ring (32) engages as soon as both recesses (52, 54) are brought into alignment during assembly.

7. Hydraulic accumulator according to one of the preceding claims, characterized in that in the fixed state of the locking ring (32) it engages with a part in the further recess (54) in the further housing part (12) under spring-elastic preload and remains with another part in the recess (52) of one housing part (10).

8. Hydraulic accumulator according to one of the preceding claims, characterized in that the two recesses (52, 54) of both housing parts (10, 12) have annular and conically tapered chamfers (58, 60) extending towards a receptacle (56) for the separating element (20), in particular in the form of a separating membrane (22).

9. Hydraulic accumulator according to one of the preceding claims, characterized in that the annular receptacle (56) for the separating element (20) is formed by inner surfaces of both housing parts (10, 12) of the accumulator housing (16) and that the recess (52) in one housing part (10) has a lesser depth than the receptacle (56) for the separating element (20).

10. Method for producing a locking ring connection (14) between two adjacent storage housing parts (10, 12) of a hydraulic storage tank, in particular according to one of the preceding claims, characterized in that, by means of an assembly aid (62), when fixing one housing part (10) together with the locking ring (32), the other housing part (12) is pushed onto the one housing part (10) from its free edge in an axial direction until the locking ring (32) snaps into an adjacent recess (54) of the other housing part (12) due to its inherent elasticity.

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