Expansion Unit

Abstract

An expansion device is disclosed, comprising an expansion housing 10, the expansion housing having a separation membrane 12 separating the expansion housing 10 into two chambers 14, 18, one of which can be filled with liquid via a liquid connection 16 in the expansion housing 10, characterized in that the other chamber 18 of the two chambers 14, 18 is permanently connected to the environment 21 via at least one opening 20 in the expansion housing 10, such that ambient pressure is present in the other chamber 18 even during operation of the expansion device.

Description

[Technical field]

[0001] The present invention relates to an expansion device comprising an expansion housing having a separation membrane separating the expansion housing into two media chambers, one of which can be filled with liquid via a liquid connection in the expansion housing. [Background technology]

[0002] DE 4302356 A1 discloses a safety group with an expandable container for installation on a cold water pipe connected to a pressure-tight water heater, the expandable container having a membrane and a tube section, at the inlet of which a backflow preventer and a downstream safety valve are arranged. The tube section is provided with an opening, the membrane of the expandable container consists of a flexible hose that is pulled over the tube section and surrounded by a pressure accumulator housing that is filled with a gas, e.g. nitrogen, under a certain pressure via a connection.

[0003] EP 943872 discloses a combined expandable vessel for domestic and heating water, with the purpose of absorbing volume changes caused by temperature fluctuations during the operation of such a system. The expandable vessel is separated by an elastic membrane into a pressurized compressed gas chamber and a water chamber connected to the water system via a connection, and the domestic water chamber and the heating water chamber are integrated into a common vessel. In this way, a domestic water expandable vessel and a heating water expandable vessel are formed, which can be subjected to different pressures, the domestic water expandable vessel consisting of the actual domestic water chamber and a further compressed gas chamber which can be filled with compressed gas at a given pressure via a filling valve.

[0004] Since the known expansion vessels are in each case continuously exposed to the relevant operating pressure formed by the working gas contained in the closed chamber, they are subject to the European Pressure Equipment Directive, which is implemented in Germany within the framework of the Pressure Equipment Ordinance. Pressure vessels are already subject to this regulation if they are operated at a maximum permissible pressure of more than 0.05 MPa (0.5 bar), which means that they must be subjected to internal or visual inspections at certain intervals and strength tests, also known as pressure tests, must be carried out at longer intervals which are correspondingly time-consuming and expensive, as well as monitoring periods for compliance with these. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent No. 4302356 [Patent Document 2] European Patent No. 943872 Summary of the Invention [Problem to be solved by the invention]

[0006] Based on this state of the art, the present invention is based on the object of further improving known solutions in such a way that they are no longer subject to the restrictive requirements of the Pressure Equipment Directive or the Pressure Vessels Ordinance in legally prescribed inspection intervals. [Means for solving the problem]

[0007] The corresponding object is achieved by an expansion device having in its entirety the features of claim 1, the invention being based on the knowledge that for many applications such an expansion device only needs to compensate for the fluctuating volume of liquid more or less without pressure, without needing a high-pressure vessel with a trapped gas volume at a given pressure, which usually exceeds the limit of 0.05 MPa (0.5 bar) in accordance with the Pressure Equipment Directive or the Pressure Vessels Ordinance.

[0008] Thus, according to the characterizing part of claim 1 of the present invention, it is provided that the other chamber is permanently connected to the environment through at least one opening in the extended housing, so that even during operation of the device, the ambient pressure is present in the other chamber. Thus, liquid with a certain pressure and volume can still flow into one of the chambers of the extended housing, so that the elastic separation membrane bulges in the direction of the other chamber, thereby displacing ambient air from this other chamber to the outside through the respective opening of the extended housing. If then a variable volume of liquid is withdrawn from one of the chambers of the container, the membrane relaxes again and returns to its original state, and then the liquid is "sucked back" again into the other chamber through the respective opening to the environment for compensation purposes. Thus, with the extended device according to the invention, it is possible to use it in a large number of applications in which only a certain variable volume must be compensated for on the liquid side, without having to comply with the stringent regulations in the field of permanently pressurized containers with operating pressures above 0.05 MPa (0.5 bar).

[0009] The expansion device according to the invention is particularly suitable for connection to any kind of fluid circuit, in particular in the form of a hydraulic circuit. In aircraft, due to the wide range of operating temperatures from +40°C to -56°C (ISA temperature), the hydraulic oil typically enclosed in the hydraulic operating circuit may expand or contract, and the resulting fluctuating volume in the hydraulic circuit can be reliably compensated by the expansion device according to the invention with little design effort. This is not comparable to the prior art.

[0010] In a preferred embodiment of the expansion device according to the invention, the liquid connection and at least one opening for passing ambient air to the other chamber are arranged on both end sides of the expansion housing. In this way, the vertical direction is substantially predetermined relative to the expansion housing during its operation, and the variable volume to be accommodated can freely enter and exit one chamber under the effect of gravity. Since the air opening is arranged at the top of the expansion housing, particularly good flow conditions are achieved when air enters and leaves the other chamber, the respective volume of which is predetermined by the expansion dimension of the elastic separation membrane, which is exposed to the variable volume on the liquid side.

[0011] In a particularly preferred embodiment of the expansion device according to the invention, it is provided that at least one opening for the passage of air in the expansion housing is used to accommodate an air filter. In this way, the air flowing into the expansion housing can be filtered out of polluting particles. If configured accordingly, the air filter can also separate moisture components from the ambient air in the usual way.

[0012] In a further particularly preferred embodiment of the expansion device according to the invention, the expansion housing consists of two shell-like housing parts that are glued together and made of plastic material, for example a conventional composite material. Since the container-like expansion housing is not exposed to high pressure, in particular only to ambient pressure, a lightweight construction made of plastic is possible.

[0013] In a further preferred embodiment of the expansion device according to the invention, one housing part with the respective opening engages over the other housing part with the liquid connection, and in the area of ​​the overlap on the inner circumference of the other housing part with the liquid opening a retaining ring is inserted, which presses the separation membrane into the annular recess of the other housing part. In this way, a gas-tight connection between the housing parts is achieved, and the membrane is fixed in place on its edge in the expansion housing by the retaining ring without additional fastening means. Preferably, one housing part with the opening protrudes inwards in the area of ​​the retaining ring and thus engages over the other housing part and the retaining ring, nevertheless resulting in a pressure-stable configuration of the expansion housing in conjunction with the shell-like structure of the housing parts.

[0014] In a further preferred embodiment of the expansion device according to the invention, it is provided that at the overlap point between the one housing part and the other housing part with the retaining ring, an axial gap is present, in this way a certain tolerance compensation is made so that in each case the retaining ring with the membrane can be reliably attached to the shell arrangement of the housing parts.

[0015] Preferably, the membrane consists of a shell-like elastomeric body having a closure on the bottom side for sealing the liquid connection when the liquid-side housing part is completely emptied, in this way the membrane can be easily moved to its closed position and the liquid can be completely drained from the other housing part.

[0016] In a preferred embodiment of the expansion device according to the invention it is further provided that the separation membrane has a bead-like thickening which engages with a lip projecting radially into an associated annular gap in the other housing part, thereby achieving an additional fixing option for the edge of the membrane in the other housing part.

[0017] In a further preferred embodiment of the expansion device according to the invention, it is provided that the liquid connection in the other housing part has two connection parts which engage through the liquid connection, and these two connection parts are fixed relative to each other to clamp the other housing part to the liquid connection in the edge area between these two connection parts. In this way, the other housing part, which may be fiberglass reinforced, is safely penetrated by the metal material of these connection parts, so that, despite the lightweight construction of the housing, a robust connection option for the hydraulic circuit with a standardized connection geometry is created. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 shows an expansion device according to the invention in longitudinal section. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In the following, the expansion device according to the invention is explained in more detail by means of a drawing embodiment, in which the essential components of the expansion device are shown in a single figure in the form of a longitudinal section.

[0020] The expansion device according to the figure has an expansion housing 10 with a partition arranged therein in the form of an elastic separation membrane 12. The separation membrane 12 separates the housing 10 in its interior into a chamber 14 which can be filled with liquid, for example in the form of hydraulic oil, via a liquid connection 16. If necessary, liquid can be drained from the chamber 14 via the liquid connection 16, which is connected in the usual way to a hydraulic supply device (not shown in detail). As can be seen, a further second chamber 18 is arranged above the separation membrane 12, which second chamber 18 is permanently connected to the environment 21 via an opening 20 in the expansion housing 10, even during operation of the device, so that ambient pressure prevails in the respective other chamber 18.

[0021] As can be seen from the figure, the liquid connection 16 and the opening 20 for the passage of ambient air to the other medium chamber 18 are arranged coaxially with the longitudinal axis 22 of the extension housing 10 at both ends of the extension housing 10 .

[0022] In a preferred embodiment of the expansion device according to the invention, it is further provided that, as shown in the figures, one opening 20 for the passage of air in the expansion housing 10 is used to accommodate an air filter 24 which is received in the opening 20 in the manner of a screwable replacement cartridge. If the air filter 24 becomes clogged with polluting particles from the ambient air, it can be easily replaced with a new air filter 24.

[0023] The extension housing 10 is essentially formed from two shell-like housing parts 26, 28, which are glued together along a given adhesive joint 30 and consist of a plastic material, preferably fiberglass reinforced plastic. However, it is also possible for the housing parts 26, 28 to be manufactured from die-cast aluminum parts, for example. Instead of the above-mentioned joining via adhesive joint 30, a different connection can also be provided, for example the two housing parts 26, 28 can be screwed together in an embodiment not shown in detail.

[0024] The upper housing part 26 with the opening 20 engages over the other housing part 24 with the liquid connection 16 along the protruding edge 32, and in the area of ​​this overlap the retaining ring 36 is inserted into the inner circumference 34 of the other housing part 28 with the liquid connection 16, which presses the separation membrane 12 into an annular recess 38 of the other housing part 28. At the point of overlap there is an axial gap in the longitudinal direction of the longitudinal axis 22 between the other housing part 28 with the retaining ring 36 and the one housing part 26. The retaining ring 36 abuts against a protruding contact surface 42 of the other housing part 28. Viewed in the direction of the figure, the annular recess 38 lies below the annular contact surface 42, above which the contact surface 42 extends in an outwardly widening cone 44, the upper boundary wall of which, viewed in the horizontal direction, also defines a gap 40 downwards.

[0025] The separation membrane 12 consists of a shell-shaped elastomer body, which has a closure part 46 on the bottom side for sealing the liquid connection 16 when the housing part 28 is completely emptied on its liquid side or on the side of one of the medium chambers 14. The closure part 46 is configured like a solid valve plate and is in particular "buttoned" at the lower end of the membrane body of the separation membrane 12. The plate-shaped closure part 46 is arranged concentrically with the longitudinal axis 22, the circumferential diameter of the closure part 46 being selected in each case such that its downwardly projecting closure edge, which is flush with the free end side of the separation membrane 12, comes into contact with a free peripheral edge 50 which defines the liquid connection 16 on the opposite inside of the other housing part 28.

[0026] Furthermore, the separation membrane 12 has at its outer free end a bead-shaped thickened portion 52, which is bounded outwardly by an annular recess 38 and inwardly towards the longitudinal axis 22 by a concave recess 54 of the retaining ring 36. The retaining ring 36 is preferably configured as an elastically flexible plastic clip part which can be inserted from above along the free opening of the other housing part 28 and snapped along the contact surface 42 via the thickened portion 52. Due to the elastic pretension, the retaining ring 36 forms a kind of retaining bracket for the thickened portion 52 of the separation membrane 12. In order to securely fix the separation membrane 12 in the other housing part 28, it is further provided that the thickened portion 52 has at its upper end a radially projecting thin-walled lip 56 which engages flush in an associated annular gap 58 in the other housing part 28. In this way, a secure fixation of the separation membrane 12 in the other housing part 28 in an axial direction parallel to the longitudinal axis 22 is also achieved.

[0027] As can be seen, the liquid connection 16 in the other housing part 28 has two connection parts 60, 62 which engage through the liquid connection 16 and which are fixed relative to one another and clamp the other housing part 28 between them in an edge region 64 of the liquid connection 16. One connection part 60 has an external thread 65 (not shown in detail) on its free end side, via which the entire expansion device with the expansion housing 10 can be connected in the usual way to a hydraulic supply circuit (not shown). One connection part 60 has an O-ring 66 on its outer periphery for the purpose of sealing a possible leakage point from the first medium chamber 14 to the environment 21. In this respect, the O-ring 66 is sealingly arranged on the inner periphery of the edge region 64 of the other housing part 28. From the inside, the further connecting part 62 is first inserted, so that on its free upper end side a flat contact surface 67 transverse to the longitudinal axis 22 is formed for contacting the closure part 46, provided that the medium chamber 14 is completely emptied of liquid. The connecting part 62 has an external thread 68 along a cylindrical hollow engagement socket, via which the hollow-cylindrical connecting part 60 with a correspondingly configured internal thread can be screwed onto the connecting part 62 from the outside. When the two connecting parts 60, 62 are fastened to one another via the designated threads, the edge region 64 is thus firmly clamped between the connecting parts 60, 62, for which reason the connecting part 62 has a flange-like widening 69 in the direction of the closure part 46, the outside diameter of which corresponds to the outside diameter of the edge 48 of the closure part 46.

[0028] In addition to or instead of the adhesive part 30, the upper housing part 26 can be configured as a clip part with an enlarged outer edge 70 and clipped onto the lower housing part 28. In this way, a housing structure is achieved which can be easily and cheaply manufactured, which makes it possible to dispense with conventional joining techniques such as gluing, screwing, etc. for connecting the housing parts 26, 28 to one another, and which allows a clip or snap connection, since only the ambient pressure prevails in the other medium chamber 18 via the opening 20 or via the air filter 24. In any case, the free edge of the outer wall 70 projects beyond the lower end side of the retaining ring 36 in the horizontal plane. To apply the necessary retention force, the circumferential outer wall 70 is enlarged in diameter towards its free end.

Claims

1. An expansion device comprising an expansion housing (10), wherein the expansion device has a separation membrane (12) that separates the expansion housing (10) into two medium chambers (14, 18), and one of the two medium chambers (14, 18) can be filled with liquid via a liquid connection part (16) in the expansion housing (10), An expansion device characterized in that the other medium chamber (18) of the two medium chambers (14, 18) is permanently connected to the environment (21) via at least one opening (20) in the expansion housing (10) such that ambient pressure is present in the other medium chamber (18) even while the expansion device is in operation.

2. The expansion device according to claim 1, characterized in that the liquid connection portion (16) and the at least one opening (20) for ambient air to pass to the other medium chamber (18) are arranged on both ends of the expansion housing (10).

3. The expansion device according to claim 1, characterized in that the at least one opening (20) for the passage of air within the expansion housing (10) is used to house an air filter (24).

4. The expansion device according to claim 1, characterized in that the expansion housing (10) consists of two shell-shaped housing parts (26, 28) that are bonded to each other and made of plastic material.

5. The expansion device according to claim 1, characterized in that one housing portion (26) having each of the openings (20) covers and engages with the other housing portion (28) having the liquid connection portion (16), a retaining ring (36) is inserted into the overlapping region on the inner circumference (34) of the other housing portion (28) having the liquid connection portion (16), and the retaining ring (36) presses the separation membrane (12) into the annular recess (38) of the other housing portion (28).

6. The expansion device according to claim 5, characterized in that one housing portion (26) having the opening (20) protrudes inward within the area of ​​the retaining ring (36) and covers and engages with the other housing portion (28) and the retaining ring (36).

7. The expansion device according to claim 5, characterized in that at the overlapping point between the other housing portion (28) having the retaining ring (36) and the one housing portion (26), there is an axial gap (40), and the other housing portion (28) abuts against the retaining ring (36) having a protruding contact surface (42).

8. The expansion device according to claim 5, characterized in that the separation membrane (12) is made of a shell-shaped elastomer body having a closing portion (46) at its bottom for sealing the liquid connection portion (16) when the other housing portion (28) is completely emptied on its liquid side.

9. The expansion device according to claim 5, characterized in that the separation membrane (12) has a bead-shaped thickened portion (52) that engages with a lip (56) that radially protrudes into a related annular gap (58) within the other housing portion (28).

10. The expansion device according to any one of claims 5 to 9, wherein the liquid connection portion (16) in the other housing portion (28) has two connecting portions (60, 62) that engage through the liquid connection portion (16), and these two connecting portions (60, 62) are fixed relative to each other, and the other housing portion (28) is clamped between these two connecting portions (60, 62) at the edge region (64) of the liquid connection portion (16).

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