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 have fluid connection points (48, 50) and are held against one another by means of a fixing ring connection (14) in order to form an accumulator housing (16), and having a separating element (20) which is arranged movably within the accumulator housing (16) and separates two media chambers (24, 26) from one another, characterised in that the housing parts (10, 12) are at least partially set into one another along adjacent wall sections (32, 34), of which one wall section (32) of the one housing part (10) protrudes beyond the other housing part (12) in the direction of the environment, thereby forming a circumferential wall (36), and surrounds a wall region (38) of the other housing part (12) such that an engagement space (40) is created which is provided at a point of the transition (42) from the one housing part (10) to the other housing part (12) for receiving a fixing ring (44) of the fixing ring connection (14).

Description

[0001] HYDAC TECHNOLOGY GMBH

[0002] Industriestraße, 66280 Sulzbach / Saar, Germany

[0003] Hydro storage

[0004] The invention relates to a hydraulic accumulator, in particular a membrane accumulator, comprising at least two housing parts having fluid connection points, which are held together by means of a locking ring connection to produce an accumulator housing and with a separating element movably arranged within the accumulator housing, which separates two media spaces from each other.

[0005] DE 10 2015 012 357 A1 describes a hydraulic accumulator, in particular in

[0006] Form of a membrane storage device, known, consisting of at least two

[0007] Housing components of a storage housing in which a separating element, in particular in the form of a separating membrane, separates two media compartments from each other, and with at least one media connection part connected to one housing component along a weld seam, wherein the connection part engages at least partially in a receiving compartment located in one

[0008] The housing part is formed along a housing opening, and the adjacent wall surfaces of the housing part and the connecting part are joined by a weld seam in the receiving space. 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 filler materials. To prevent weld spatter from unintentionally reaching the inside of the storage housing with its sensitive elastomeric separating membrane during the welding process, the weld seam to be produced is completely covered on the inner circumference by an annular projection on one of the two housing parts.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] Based on this prior art, the invention aims to further improve known solutions while retaining their other advantages, in particular to connect two housing parts of a storage tank housing for the purpose of creating a hydraulic accumulator in a reliable and cost-effective manner and in a way that is easy to assemble. A hydraulic accumulator with the features of claim 1 as a whole solves this problem.

[0013] According to the characterizing part of claim 1, the housing parts are at least partially interlocked along adjacent wall sections, one wall section of which projects over the other towards the environment, forming a circumferential wall, and encompasses a wall area of ​​the other housing part in such a way that an engagement space is created which is provided at a point of the transition from one housing part to the other housing part for receiving a retaining ring of the retaining ring connection, the retaining ring connection is an integral part of the structure for the storage housing and is protected by the circumferential wall projecting far outwards in such a way that an unintentional loosening of the connection cannot occur, which increases functional reliability, especially in the event of a correspondingly high fluid or media pressure inside the storage housing.The locking ring connection is easy to assemble and can be loosened again, if necessary, to separate the housing parts. The locking ring, preferably designed as a slotted spring washer, is readily available in a wide variety of versions, allowing for a cost-effective solution. In particular, these locking rings are standardized (e.g., DIN 9926:2016-1), which simplifies their use in hydraulic accumulator designs.

[0014] In a preferred embodiment of the hydraulic accumulator according to the invention, the engagement chamber is wedge-shaped in cross-section and the wedge tapers conically towards the locking ring, the wedge shape of the engagement chamber acting as an assembly aid to ensure that the locking ring can be securely fixed in the corresponding receptacle, in particular in the housing part with the protruding circumferential wall.

[0015] In a further preferred embodiment of the hydraulic accumulator according to the invention, the cone angle of the conical taper between a tangent applied to the top surface of the other housing part and an imaginary extension on the inside of the circumferential wall of one housing part is 30° to 70°, preferably 40° to 60°, and particularly preferably 45°. This creates a kind of self-locking effect that ensures the locking ring remains securely in its locking position between the two housing parts.In a further preferred embodiment of the hydraulic accumulator according to the invention, the nested wall sections of both housing parts are designed as hollow cylinders, as is the circumferential wall of one housing part, and an end wall of the other housing part, which projects outwards towards the surroundings as viewed from the retaining ring, is provided with a predetermined curvature, forming a dome. This results in a particularly pressure-stable arrangement when the accumulator housing is completed, which can withstand even high media pressures inside the accumulator housing.

[0016] In a further preferred embodiment of the hydraulic accumulator according to the invention, an annular receiving groove is provided in one housing part for receiving the retaining ring. This groove is at least partially concave in the direction of the free edge of the circumferential wall when viewed from the other housing part and extends in the other direction as a guide chamfer that opens into the hollow cylindrical wall section of the other housing part. Preferably, the other housing part has a circumferential, nose-like projection at the point of transition from its hollow cylindrical wall section to its exposed, preferably curved, end wall. This projection is cut away from the outer surface of the other housing part at the point of transition to the cylindrical wall section, forming a shoulder.In this way, the locking ring is at least partially secured in the receiving groove of one housing part in a self-locking and self-locking manner.

[0017] In a further preferred embodiment of the hydraulic accumulator according to the invention, the cut-out section of the other housing part, in the fixed state, opens towards the guide ramp, which in this area is provided with a convex, outwardly projecting section and transitions into a straight section that opens onto the inside of the hollow cylindrical wall section of one housing part, forming the circumferential guide ramp. In this way, a smooth and continuous transition is achieved between the receiving groove in one housing part and the associated guide ramp, which forms a tapered conical angle in the direction of contact with the other housing part. Preferably, the receiving groove, at least in the area of ​​contact with the locking ring, follows the circular cylindrical outer contour of the locking ring, forming at least a quarter circle.

[0018] In a further particularly preferred embodiment of the hydraulic accumulator according to the invention, a cover is provided along the free edge of the circumferential wall to prevent water accumulation and thus provide corrosion protection. This cover extends over the working area, and parts of the other housing part open out through the central opening of this cover. Alternatively, at least one drainage channel is provided that penetrates the circumferential wall and opens inwards at the location of the retaining ring. Due to the cover, the working area is protected from the ingress of corrosive media, and any corrosive media that may unintentionally enter the working area can be discharged back into the environment of the hydraulic accumulator via the respective drainage channel.

[0019] The hydraulic accumulators discussed here have one housing section with a fluid connection, in particular a liquid connection for a hydraulic medium such as hydraulic oil, and the other housing section has a further fluid connection, in particular a gas connection for a working gas such as nitrogen gas. Furthermore, 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 (working chamber) from a gas chamber (another working chamber). The diaphragm thus decouples the gas and liquid chambers.The fluid chamber is regularly connected to a hydraulic circuit of the hydraulic system via the fluid connection of the accumulator housing. This allows the accumulator to absorb hydraulic fluid when the pressure in the hydraulic circuit increases, compressing the working gas. When the pressure decreases, the previously compressed working gas expands, displacing the fluid back into the hydraulic circuit. In this respect, such accumulators can serve as energy storage devices for energy recuperation in technical systems.

[0020] The hydraulic 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 general, not to scale, representation of the...

[0021] Figure 1 shows a longitudinal section through the hydraulic accumulator as

[0022] Whole;

[0023] Figure 2 shows, in enlarged view, the contents of a box labeled X in Figure 1.

[0024] Figure 1 shows a hydraulic accumulator in the form of a so-called 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 a pressure-resistant 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 from each other. For this purpose, the separating membrane 22 is designed in a cup- or bowl-shaped manner, resembling a dome, and is fixed within the accumulator housing 16 at its free circumferential edge 28, which is provided with a thickening.Furthermore, a sealing element 30 is injection-molded into the bottom of the separating membrane 22 for improved sealing of one fluid chamber 24 of the accumulator housing 16 in relation to the piping of a hydraulic circuit (not shown in detail), to which such a hydraulic accumulator is regularly connected. This design is also common, so it will not be discussed further here.

[0025] As can be seen further in Figure 1, the two housing parts 10, 12 are at least partially interlocked along adjacent hollow cylindrical wall sections 32, 34, with the other housing part 12 engaging with the first housing part 10 to approximately its midpoint. The outer wall section 32 of the housing part 10 is extended upwards when viewed in the direction of Figure 1 and forms an axially projecting circumferential wall 36, which is slightly wider than the wall diameter of the wall section. The circumferential wall 36, which projects axially outwards towards the surroundings, encompasses a wall area 38 of the other housing part 12, spaced apart such that an annular engagement space 40 is created. This engagement space, located at the transition 42 from the first housing part 10 to the second housing part 12, is designed to receive a retaining ring 44 of the retaining ring connection 14.

[0026] The retaining ring 44 is designed as a slotted spring ring in the manner of a snap ring, and the slot 46 in the corresponding ring body is shown on the left when viewed from the side of Figure 1, where the slot 36 provides a partial end-face view of the ring body of the retaining ring 44, which is provided with a predefinable ring diameter. Specifically, this retaining ring 44 is a standardized snap ring made of elastic spring steel material, which is also subject to a standard. The lowermost housing part 10 has a fluid connection 48, in particular in the form of a liquid connection for a hydraulic medium, such as hydraulic oil. In contrast, the other housing part 12, arranged above it, has a further fluid connection 50, in particular in the form of a gas connection for a working gas, such as nitrogen gas.The additional fluid connection 50 has a through central opening which is closed in the usual manner by a sealing screw 52. The additional fluid connection 50 and the sealing screw 52 are covered by a screw-on protective cover 54, preferably made of plastic material, at least during transport.

[0027] As can be seen particularly from the detailed view in Figure 2, the engagement space 40 is wedge-shaped in cross-section, and the wedge tapers conically towards the locking ring 44 and the transition 42 between the two housing parts 10 and 12. The cone angle Y of the conical taper between a tangent 56, applied to the corresponding upper surface 58 of the other housing part 12, and an imaginary extension on the inner surface 60 of the circumferential wall 36 of one housing part 10 is preferably 45° in this case. In this way, the inner circumference of the locking ring 44 slides in a particularly advantageous manner on the upper surface 58 of the other housing part 12 until it assumes its locking position, as shown in Figures 1 and 2, in a virtually self-locking and self-secured manner, and then remains permanently in this locking position.Depending on the design of the hydraulic accumulator, other angles of intervention, i.e., cone angles, can also be used, typically between 30 and 70° and preferably between 40 and 60°. The nested wall sections 32, 34 of both housing parts 10, 12 are hollow cylindrical, as are the projecting circumferential wall 36 of one housing part 10 and a terminal wall 62 of the other housing part 12, which, viewed from the retaining ring 44, projects outwards towards the surroundings and has the wall area 38 at its base. This terminal wall 62 is provided with a dome-like cup 64 with a predetermined curvature that decreases towards the retaining ring 44 and preferably transitions into a flat plane.

[0028] As can be seen particularly from Figure 2, an annular receiving groove 66 is provided in one housing part 10 for receiving the retaining ring 44. This groove is concave in the direction of the free edge of the circumferential wall 36, at least partially with respect to the one housing part 10, i.e., facing outwards. In the opposite direction, it extends a guide ramp 68, which forms a truncated cone and opens into the hollow cylindrical wall section 32 of one housing part 10. The other housing part 12 has, at the point of transition from its hollow cylindrical wall section 34 to its exposed, preferably curved, end wall 62, a nose-like projection 70 that extends at least partially around the perimeter. Viewed in the direction of Figure 2, this projection opens approximately centrally onto the upper surface of the opposite guide ramp 68.The nose-like projection 70 is cut free at the point of transition to the cylindrical wall section 34 of the other housing part 12, opposite its outer side and forming a shoulder 72.

[0029] This cut-out section of the other housing part 12, in the form of the shoulder 72, opens in the fixed state, i.e., in the direction of the guide slope 68, which in this contact area is provided with an overlying convex section 74, into a straight section 76 of the guide slope 68, which is guided on the inside of the hollow cylindrical wall section 32 of one housing part 10. The change from the concave receptacle for the locking ring 44 to the straight guide slope 68 with the intervening convex transition ensures secure guidance of the two housing parts 10, 12 relative to each other during assembly, as well as reliable guidance when locking the locking or expanding ring 44 in the associated receiving groove 66 in the outer housing part 10.In this respect, the recording ut 66 follows at least in the area of ​​the facility with the fixing ring 44, whose circular cylindrical outer contour forms a quarter circle.

[0030] When the inner, additional housing part 12 is inserted along the free upper surface of the first housing part 10, the separating element 20, or rather the separating membrane 22, with its circumferential edge 28, is already secured in a corresponding wall recess in the lower region of the additional housing part 12. The additional housing part 12 is then pushed into the first housing part 10 until the housing parts 10 and 12 are aligned, with the wall regions 32 and 34 abutting each other on their adjacent inner and outer circumferential sides. The additional housing part 12 can be inserted into the housing part 10 until the nose-like projection 70 comes into contact with the guide chamfer 68, thus forming a stop that prevents further insertion of the housing part 12 into the housing part 10.Due to the special arrangement of the projection 70 with the guide 68, tight tolerances are not required, as contact with the nose-like projection 70 is possible over a wide area of ​​the guide chamfer 68. Once the two housing parts 10 and 12 are nested, the locking ring 44 can be placed onto the top surface 58 of the dome 64 from above. The slotted locking ring 44 expands under spring preload and then slides into the receiving groove 66 on the housing part 10, snapping into place. The locking ring 44 then exerts a clamping force on the housing part 12 to hold it within the housing part 10. The curved or angled top surface 58 of the dome 64 plays a corresponding role in the clamping action exerted by the locking ring 44.To create a smooth transition between the hollow cylindrical wall section 34 of the housing part 12 and the adjoining dome 64, the wall sections of the further housing part 12 in the area of ​​the assembly with the locking ring 44 are more robust than the wall sections above and below, thus providing improved support for the locking ring 44. If necessary, the locking ring 44 can also be disengaged in the opposite direction, for example, to replace the separating element 20 with a new one in case of failure.

[0031] For corrosion protection, a cover 78 is provided along the free inner edge of the circumferential wall 36, covering the engagement space 40, and parts of the dome-shaped other housing part 12 open out along its central opening 80. Preferably, alternatively or additionally, several drainage channels 82 may be provided, extending completely through the circumferential wall 36 and opening inwards at the location of the retaining ring 44, preferably in an area that runs below the contact area between the retaining ring 44 and the receiving groove 66.

[0032] The hydraulic 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 for joining the two housing parts 10, 12 as the accumulator upper and lower parts as efficiently as possible in a pressing or other joining process during the membrane insertion process. In this way, only low investment costs are required for the production of the accumulator assembly.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 44 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.

[0033] 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 snap-ring connection solution described above avoids this and enables the extremely rapid production of a storage housing 16 from two storage housing parts 10, 12. This has no equivalent in the prior art.

Claims

P a t e n t a n s p r ü c h e 1. A hydraulic accumulator, in particular a diaphragm accumulator, comprising at least two housing parts (10, 12) having fluid connection points (48, 50), which are held together by means of a locking ring connection (14) to form an accumulator housing (16) and with a separating element (20) movably arranged within the accumulator housing (16), which separates two media spaces (24, 26) from each other, characterized in that the housing parts (10, 12) are at least partially nested along adjacent wall sections (32, 34), one wall section (32) of one housing part (10) projecting over the other (12) to form a circumferential wall (36) towards the surroundings and encompassing a wall area (38) of the other housing part (12) in such a way that an engagement space (40) is created.which is provided at a point of the transition (42) from one housing part (10) to the other housing part (12) for receiving a retaining ring (44) of the retaining ring connection (14).

2. Hydraulic accumulator according to claim 1, characterized in that the engagement space (40) is wedge-shaped in cross-section and the wedge in that direction tapers conically towards the fixing ring (44).

3. Hydraulic accumulator according to claim 1 or 2, characterized in that the cone angle (Y) of the conical taper between a tangent (56) applied to the top (58) of the other housing part (12) and an imaginary extension on the inside (60) of the circumferential wall (36) of one housing part (10) is 30° to 70°, preferably 40° to 60°, particularly preferably 45°.

4. Hydraulic accumulator according to one of the preceding claims, characterized in that the nested wall sections (32, 34) of both housing parts (10, 12) are formed as hollow cylinders, as is the circumferential wall (36) of one housing part (10), and that a terminal wall (62) of the other housing part (12), which projects outwards towards the environment as seen from the retaining ring (44), is provided with a predetermined curvature forming a dome (64).

5. Hydraulic accumulator according to one of the preceding claims, characterized in that an annular receiving groove (66) is provided in one housing part (10) for receiving the retaining ring (44), which is at least partially concave in the direction of the free edge of the circumferential wall (36) when viewed in the direction of one housing part (10) and has a guide ramp (68) extending in the other direction, which opens into the hollow cylindrical wall section (32) of one housing part (10).

6. Hydraulic accumulator according to one of the preceding claims, characterized in that the other housing part (12) has a circumferential, nose-like projection (70) at the point of transition from its hollow cylindrical wall section (34) to its exposed, preferably curved, end wall (62).

7. Hydraulic accumulator according to one of the preceding claims, characterized in that the nose-like projection (70) at the point of transition to the cylindrical wall section (34) of the other housing part (12), opposite its outer side and forming a shoulder (72), is cut free.

8. Hydraulic accumulator according to one of the preceding claims, characterized in that the cut-out section of the other housing part (12) opens in the direction of the guide ramp (68) in the fixed state, which in this area is provided with a convex section (74) and transitions into a straight section (76) which opens on the inside of the hollow cylindrical wall section (32) of one housing part (10) forming the circumferential guide ramp (68).

9. Hydraulic storage tank according to one of the preceding claims, characterized in that the receiving groove (66) at least in the area of ​​the system with the fixing ring (44), whose circular cylindrical outer contour follows the formation of at least a quarter circle.

10. Hydraulic accumulator according to one of the preceding claims, characterized in that, for corrosion protection, a cover (78) covering the engagement space (40) is provided along the free edge of the circumferential wall (36), along whose central opening (80) parts of the other housing part (12) open out and / or that at least one drainage channel (82) is provided which penetrates the circumferential wall (36) and opens inwards at the location of the retaining ring (44).

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