EP3099940B1 - Pressure accumulator - Google Patents

Description

The invention relates to a pressure accumulator, comprising a storage housing in which a movable separating element fluid-tightly separates a gas space which can be filled with a working gas from a fluid space, wherein a monitoring device is provided which provides an optically recognizable display in an accident affecting the sealing effect of the separating element.

Hydropneumatic accumulators of this type are state of the art. They are widely used in fluid systems and hydraulic systems, for example as a pulsation damper for smoothing pressure fluctuations or for storing hydraulic energy. The document EP 1 709 334 B1 discloses, for example, a pressure accumulator of this type in the form of a bellows accumulator, which is provided in particular as a pulsation damper. For the functionality of such memory, it is crucial that the separating element between the working spaces, gas side and fluid side, forms an absolute separation and maintains this during operation. A defect occurring at the separating element, be it a bellows or a membrane, which leads to a fluid transition to the gas side and thus to a reduction of the gas volume, leads to progressive reduction of the damping effect in the case of pulsation dampers or to loss of the storage capacity in the case of energy stores.

An accumulator of the type mentioned is out DE 10 2011 100 532 A1 known. The known hydraulic accumulator comprises a movable separating device for separating two media, which are received in different media spaces, wherein by means of a measuring device, a passage of at least one medium of a media space on the separating device in the other media space with the other medium is detectable. In this case, the measuring device has at least one sensor element, which can detect the passage of media via the separating device and is connected to a locking point of the storage housing. The connection is made via a flexible cable connection, wherein the cable is connected at its one end to the sensor element and is connected at its other end to the lock with parts of the storage enclosure that at least partially limits the media spaces. About the lock of the storage enclosure, the sensor element is connected to an evaluation for the evaluation of measurement signals. The evaluation electronics comprises an output unit for displaying an accident detected via the sensor element.

Movable separating elements in the form of bellows or elastomeric membranes are exposed to high mechanical loads during operation, so that there is a risk of breakage during operation. In-service accumulators, it is difficult to detect such a malfunction quickly and in a timely manner that the accumulator can be replaced before malfunction or failure of a related system occurs.

In view of this problem, the invention has for its object to provide a pressure accumulator available, which ensures increased reliability in conjunction with an associated fluid or hydraulic system.

According to the invention this object is achieved by a pressure accumulator having the features of claim 1 in its entirety.

A significant feature of the invention is accordingly that the monitoring device on the wall of the housing has a viewing window through which an indicator is observable, which is in communication with the gas space and whose optical properties change noticeably when wetted with fluid. The fact that a fluid transfer to the gas side by observing an indicator can be seen through a viewing window, the function monitoring can be carried out particularly easily and safely during operation.

This opens up the advantageous possibility to perform the functionality of the accumulator during operation of the system, so without the pressure accumulator should be removed from the system and subjected to an external functional test. An expansion of a relevant accumulator from the system is therefore required only when an accident has occurred. The replacement of a defective accumulator can therefore be made before it comes to a major malfunction or the failure of the associated system, so that improved reliability can be achieved.

With particular advantage, the invention is provided in a pressure accumulator, which has a bellows as a separating element, in particular in the form of a metal bellows. Bellows, in particular metal bellows, are preferably used in pulsation dampers, where high mechanical alternating loads occur during operation on the bellows, in particular at the folds, and there is a corresponding risk of the occurrence of a defect. Therefore, the possibility of monitoring provided by the invention has a particularly advantageous effect.

In a particularly advantageous manner may be provided when moistening its color changing indicator.

In advantageous embodiments, a sample amount of fiberglass wool is provided as an indicator, which is white in the unwetted state and discolored when wetted with fluids of different types in different ways visually recognizable. When operating with a fluid in the form of hydraulic oil, a possible leakage is recognizable by a relatively dark discoloration of the glass fiber wool. When using the pressure accumulator in fuel systems wetting by diesel oil leads to a contrast less dark discoloration. For example, lead petrol or ethylene glycol to a yellowish or orange discoloration, ie to discoloration, which are certainly distinguishable from the white starting state of fiberglass wool.

In advantageous embodiments, the glass fiber wool is arranged in a bore leading through the wall of the housing to the gas space.

The bore can be closed on the outside of the housing by a threaded insert, which has a pressure-resistant viewing window, the arrangement can be taken with particular advantage so that the glass fiber wool in the bore between the viewing window having threaded insert and located at the inner end of the bore strainer is arranged. However, it may also be sufficient to observe only via the viewing window or sight glass in order to be able to detect damage to the separating element even without an indicator by an operating or maintenance person.

With particular advantage, the arrangement may be made such that the bore is formed as a continuous threaded bore, with the inner end of a threaded ring is screwed, which forms the holder for the screen body. For the monitoring device, this results in a particularly simple structural design.

In the case of pressure accumulators having a cylindrical housing which has a housing cover forming an axial housing end at one end, the bore of the monitoring device can advantageously be formed in the housing cover.

The invention with reference to an embodiment shown in the drawing is explained in detail.

Fig. 1

einen Längsschnitt eines Ausführungsbeispiels des erfindungsgemäßen Druckspeichers;

Fig. 2

einen gegenüber Fig. 1 in größerem Maßstab gezeichneten Längsschnitt des ein Sichtfenster aufweisenden Gewindeeinsatzes des Ausführungsbeispiels;

Fig. 3

einen im gleichen Maßstab wie Fig. 2 gezeichneten Längsschnitt eines weiteren Gewinderinges mit Siebkörper und

Fig. 4

eine perspektivische Schrägansicht des Gewinderinges von Fig. 3.

Show it:

Fig. 1

a longitudinal section of an embodiment of the pressure accumulator according to the invention;

Fig. 2

one opposite Fig. 1 drawn on a larger scale longitudinal section of a viewing window having threaded insert of the embodiment;

Fig. 3

one on the same scale as Fig. 2 drawn longitudinal section of another threaded ring with strainer and

Fig. 4

an oblique perspective view of the threaded ring of Fig. 3 ,

The illustrated in the drawing embodiment of a pressure accumulator in the form of a metal bellows is especially intended for use in hydraulic systems and fuel systems to dampen pressure surges of the operating medium and smooth. In the field of fuel systems is intended in particular to diesel fuel, gasoline or the like. Furthermore, a pressure accumulator could also be used in electrohydraulic brake systems, for example in vehicle construction. The pressure accumulator shown has a designated as a whole with 2 memory housing, with a substantially circular cylindrical, a longitudinal axis 4 defining cup-shaped main body 6. The main part 6 has at one end as a housing closure a housing cover 8, which is connected to the main part 6 by flipping the end edge 10 is connectable to an inclined surface 12 of the lid 8, wherein an O-ring 14 forms the seal. The folded end edge 12 may be connected to the housing cover 8 by means of an additional weld (not shown). In the housing cover 8, a (also not shown) filling connection for the introduction of a working gas, such as N _{2 may be provided} in a gas side working space, the Fig. 1 is referred to as the gas space 16.

At the end opposite the cover 8, the main part 6 of the storage housing 2 has a base 18 on which, coaxially to the longitudinal axis 4, a fluid connection with a cylindrical connecting body 20 is provided. This has two fluid ports 22, 24, which open into a common input space 26, which leads to the fluid side 28 in the housing 2. As a separating element between the gas chamber 16 and the fluid chamber 28, a metal bellows 30 is provided in the present embodiment, which, as in the mentioned, from EP 1 709 334 B1 known pressure accumulator, with its one end 32 with an inner, annular extension 34 of the lid 8 is sealed by welding. The metal bellows 30 surrounds the outside of a circular cylindrical, inner pot body 36 which is open at the end facing the housing bottom 18. With the open edge 38 of the pot body 36, the other Balgende 40 is sealed by welding.

To form the monitoring device, which indicates an indication of a fluid transfer from the fluid chamber 28 to the gas chamber 16 by a bellows break, in the present embodiment in the housing cover 8, offset from the longitudinal axis 4, a continuous threaded bore 44 is formed. The threaded bore 44 is sealed at the outer end by means of a threaded insert 46. In the inner end of the threaded bore 44, a threaded ring 48 can be screwed. The outer threaded insert 46 is formed by a screw sight glass, which has a viewing window 50 made of pressure-resistant glass. In the present example, this one by the company Herberts Industrial Glass, Gewerbeschulstr. 72, D-42289 Wuppertal, commercially available under the name "Metaglas" screw sight glass provided, which contains a viewing window 50 made of borosilicate glass. The threaded ring 48, which is screwed into this at the inner end of the threaded bore 44, carries a screen body 52. This forms a support for an intended as an indicator amount of fiberglass wool 54, which is located between the screen body 52 and the viewing window 50 of the threaded insert 46.

As the 3 and 4 Most clearly, the screen body 52 is in the form of a hemispherical dome formed of a metallic support fabric, in the present example, with a mesh size of 0.1 mm. About the outside of the support fabric also extends a metallic support fabric 56 with a mesh size of 0.83 mm at a wire thickness of 0.22 mm.

The fiberglass wool 54, which is white in its unwetted starting state, discolored upon wetting by fluid which, in the event of a defect of the separating element, in the present case a bellows break, passes from the fluid space 28 to the gas space 16. In the case of fluids such as hydraulic oil or diesel fuel, a strong darkening of the glass fiber wool 54 observable via the viewing window 50 occurs. Other fluids, depending on their color, lead to different discoloration of the indicator, for example to less dark discoloration in gasoline fuels and the like. In any case, the wetting of the gas fiber wool 54 serving as indicator is reliably recognizable via the viewing window 50. It is understood that instead of the glass fiber wool 54 as an indicator other substances can be provided which optically change their optical property when wetted with the fluids in question, in particular discolored, the initial state of the unwetted indicator does not necessarily have to be white.

While a simplified embodiment is described above, in which optical changes of the indicator are directly visually recognizable by observation through the viewing window 50, it should be emphasized that the invention is equally advantageous if appropriate accumulators are installed such that an immediate Blickkontant for visual observation of the viewing window 50 is not possible. In these cases, an optical sensor device of known type may be provided, for example including one the indicator through the viewing window 50 through light source. As an indicator is any substance in question, which changes when wetted their optical property or reflectivity in a manner detectable by the sensor device. As already mentioned, color changes do not have to start from the initial state. It may also be monochrome changes in reflectivity.

The viewing window 50 can also be glued into the housing part 46, which is designed as a threaded insert. Another possibility is to produce a pressure-tight interference fit between the viewing body 50 designed as a viewing window and the housing part 46. This may be done by suitable Einpassvorgänge of equip, but particularly preferred is the production of a kind of frictional connection between the viewing window 50 and associated housing part 46. As part of a pertinent frictional connection between the adjacent wall portions of the viewing window 50 and housing part 46, a physical and / or chemical pressure-resistant connection occur. As a further alternative solution would also be conceivable to manufacture the housing part 46 integrally with the viewing window 50, in particular the housing part 46 completely formed of a transparent material, in particular pressure-resistant glass material.

Claims (9)

1. Pressure accumulator with an accumulator housing (2), wherein a moveable separating element (30) separates a gas chamber (16) which can be filled with a working gas from a fluid chamber (28) in a fluid-tight manner, wherein a monitoring device (50, 54) is provided which provides a visually detectable display in the event of separating element (30) malfunctioning such that it leaks, characterised in that the monitoring device has a viewing window (50) in the wall of housing (2) which can be observed via an indicator (54) connected to gas chamber (16) whose optical characteristics change noticeably when wetted with fluid.
2. Pressure accumulator in accordance with claim 1, characterised in that it has a bellows, particularly in the form of metal bellows (30) as a separating element.
3. Pressure accumulator in accordance with one of the preceding claims, characterised in that an indicator (54) is provided which changes its colour when wetted.
4. Pressure accumulator in accordance with claim 3, characterised in that a sample quantity of glass fibre wool (54) is provided as indicator, which is white when unwetted and discolours visibly in different ways when wetted with fluids of different kinds.
5. Pressure accumulator in accordance with claim 4, characterised in that glass fibre wool (54) is arranged in a bore (44) which leads through the wall of housing (2) to the gas chamber (16).
6. Pressure accumulator in accordance with claim 5, characterised in that bore (44) is closed on the outside of housing (8) by a threaded insert (46), which has a pressure-resistant viewing window (50).
7. Pressure accumulator in accordance with claim 6, characterised in that glass fibre wool (54) is arranged in bore (44) between the viewing window (50) with a threaded insert (46) and a filter body (52) at the inner end of the bore (44).
8. Pressure accumulator in accordance with claim 7, characterised in that the bore is made as a continuous threaded bore (44) to the inner end, of which a threaded ring (48) may be screwed to form the holder for filter body (52).
9. Pressure accumulator in accordance with one of claims 5 to 8, characterised in that it has a cylindrical housing (2) with a housing cover (8) forming an axial housing end, in which the bore (44) of the monitoring device is made.

Images