EP2588761B1 - Pressure store - Google Patents

Description

The invention relates to a pressure accumulator comprising sub-chambers arranged in a housing, a first sub-space arranged between the housing and a flexible separating membrane, a second sub-space arranged between the separating membrane and a supporting body and a third sub-space encompassed by the supporting body, wherein the first sub-space comprises a first fluid can be filled, wherein the second subspace and the third subspace fluidly connected to each other and can be filled with a second fluid, and wherein the first and the second subspace vary by movements of the separation membrane depending on the respective filling state in their respective size, wherein the first fluid a Storage medium and the second fluid is a working medium, and wherein the second subspace increases upon removal of storage medium from the pressure accumulator and reduced upon filling of the pressure accumulator with storage medium.

Such an accumulator is off DE 101 13 415 A1 known. In the known pressure accumulator in the form of a hydropneumatic pressure accumulator, a flexible separating element is arranged in a storage housing, formed by a pipe end piece, and surrounds a support body having fluid passages. The support body has at least sections on a non-circular cross-sectional shape. The partition is anchored to form a seal on the storage housing so that on the outside and Inside the separating element each separate receiving spaces are formed. A centrally located, through bore forms a passage for a storage medium leading to the internal receiving space of the storage. For filling the outside gas space, a gas valve is provided. The known pressure accumulator can be used for energy storage, for example in conjunction with vehicle suspensions, or as a pulsation damper. Furthermore, the known solution is particularly suitable for damping pressure peaks in hydraulic or other fluid power systems. For use as an accumulator for storage media in the form of chemically aggressive fluids, such as urea-water solution, the known solution leaves nothing to be desired.

Another accumulator is off DE 38 10 509 C2 known. A pressure accumulator is known, comprising a container main body with an outer tube of cylindrical shape, at one end of a side plate and at the other end a lid is arranged, at least one inlet opening and an outlet opening, which are formed on the outer tube, and a bladder or A membrane for dividing the interior of the container main body into a gas chamber and a liquid chamber, wherein an opening of the bubble is sealed by the lid. An insert is arranged to project into the bladder for the purpose of reducing the volume of the gas chamber. The insert is formed of a foot part, a middle part and a head part, wherein the head part is kept in contact with the bottom of the membrane, which makes it possible to prevent damage to the membrane by repeated contraction. In the contracted state, the bladder or membrane rests against the insert.

From the GB 877,800 is a damper known for pulsations in fluid carrying lines. In a steel housing of the damper is a arranged movable membrane which separates a compressible gas space from a liquid space. The membrane may be supported on a spherical support member having circumferentially distributed bores.

Pressure accumulators of this type are widely used in various sizes and structural designs to receive and deliver varying volumes of subject fluids that are under the operating pressure of a fluid system connected to the fluid side, with the bladder on its gas side under a biasing pressure of the working gas forming a pressure pad , The reliability of the pressure accumulator depends primarily on the usually made of a plastic material, especially butyl, existing from memory bladder, which is not only exposed to mechanical stresses in operation, but should also be resistant to chemically aggressive storage fluids. As has been shown, it is not yet possible in connection with aggressive fluids, such as urea-water solutions, to ensure a trouble-free life of sufficient length during continuous operation, for example over 20,000 hours.

The so-called "urea injection" is increasingly being used in automotive engineering to reduce nitrogen oxide (NOx) emissions by injecting it into the exhaust gas stream from internal combustion engines. In such an application, it is particularly important that a long service life in continuous operation is achievable trouble-free.

In view of this, the invention has the object of providing a pressure accumulator which, in conjunction with aggressive storage media, is distinguished by improved operational reliability and is accordingly particularly suitable for use in urea injection in vehicle technology.

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

According to the invention, it is provided that the support body has the shape of a longitudinally approximately V-shaped body of revolution rounded at the end facing the first compartment and formed closed and provided with at least one lateral wall opening as a passage point between the second and third compartment. In this design, the support body for the separation membrane or storage bubble forms a large-area support, so that the pressure-exceeding virtually crease-free adjacent storage bubble is optimally protected.

The first fluid is a storage medium and the second fluid is a working medium, wherein the second subspace increases upon removal of storage medium from the pressure accumulator and decreases upon filling of the pressure accumulator with storage medium. By the volumes of the second and the third subspace the male amount of working medium is determined. When filling the first subspace with storage medium, the flexible separation membrane is moved to the effect that the adjoining outside of the support body to the third subspace second subspace is reduced. Accordingly, when removing or decreasing filling of the first subspace with storage medium, the second subspace is increased.

Advantageously, the pressure accumulator is designed as a hydropneumatic bladder accumulator for a gaseous working medium and / or a liquid storage medium. Particularly preferably, the pressure accumulator for filling a storage medium in the form of a chemically aggressive fluid, such as urea-water solution is formed. This allows a use the pressure accumulator according to the invention in the urea injection, especially in the automotive field.

In a particular embodiment of the pressure accumulator according to the invention, the support body and the separation membrane are shaped and dimensioned such that the support body for a separation limit beyond a definable volume volume of the first subspace, in other words at a maximum value for the recorded storage medium volume size, a support for the separation membrane forms.

Further, it is advantageous if the housing and the separation membrane are shaped and dimensioned in such a way that the separation membrane rests at least partially against the housing when the first subspace is completely emptied. Alternatively, the separation membrane may be shaped and dimensioned such that it is spaced apart from the support body and spaced from the housing upon complete emptying of the first subspace.

The support body or the housing thus form an effective protection for the separation membrane against overstressing at pressure exceedances in the first and second subspace by the separation membrane or the reservoir bubble may abut the support body or on the housing and is thereby protected in pressure exceeding a crushing , The reduced mechanical stress leads to an increase in the safe life of the separation membrane, even when exposed to chemically aggressive media, such as a urea-water solution.

Typically, the housing has a head part which adjoins the second and / or third subspace and forms the closure of the housing. The housing is suitably cup-shaped, wherein the first subspace is arranged on the bottom side. In the head part, a connection device for the second fluid can be provided.

Further, it is advantageous if a holding body is provided on the head part, on which the opening edge of the separating membrane is anchored. The holding body preferably forms a holding part, on which the supporting body is arranged. This results in a particularly compact design of the pressure accumulator.

In a particular embodiment of the pressure accumulator according to the invention, the holding body has the shape of a bell whose bell casing surrounds a fourth subspace adjoining the third subspace. In this way, the absorption capacity of the pressure accumulator for the second fluid or the typically gaseous working medium is increased and at the same time reduces the material requirement for the formation of the pressure accumulator.

With regard to the design of the head part, the arrangement may advantageously be made so that the head part has a screwed to the housing cover part with inner wall parts in the form of a concentric to the axis of the housing spherical cap, and that within the cover part of the holding body is arranged such that between the Outer wall in the form of spherical surface parts and the inner wall parts of the lid part, a gap for receiving an adjacent to the opening edge edge region of the separation membrane is formed.

A particularly secure anchoring of the separating membrane can be achieved if the holding body has, in an axially offset from its holding part in the direction of the connection means a machined into the outer wall annular groove in the anchoring of the separation membrane engages a peripheral edge surrounding the edge bead.

In particularly advantageous embodiments, the connection device has a screw socket which engages through an opening concentric to the central axis of the cover part and which pulls the holding body against the inner wall of the cover part by screwing with the cover part and clamps the located in the gap edge region of the separation membrane.

With particular advantage, the arrangement may be made such that the holding body forms a circular cylinder in the region of the holding part, on the edge region of which latching elements are formed which form a snap-in connection with counter-elements on the supporting body. This type of anchoring of the support body is particularly easy to install and allows low production costs.

The locking elements can be offset from the end edge of the outer wall of the holding part and formed by depressions of the outer wall of the holding part, in which a bead-like, radially inwardly projecting projection on the inside of the support body can be snapped.

Alternatively, the latching elements on the inner wall of the holding member may be formed by a recess axially remote from its end edge and a radially inwardly projecting, adjoining the end edge projection which can be latched with counter-elements of distributed over the circumference of the opening of the support body latching fingers. In a ring of individual detent fingers thus formed, the assembly is particularly simple and convenient. The same applies to embodiments in which the latching takes place on the outside of the holding part. Also in this case, individual locking fingers may be provided at the end edge of the support body.

The support body is preferably formed from a plastic material. With particular advantage this glass fiber-reinforced polyarylamide IXEF ^®, a material, which is distinguished over conventional glass fiber reinforced plastics by a smooth, closed outer skin can be provided. Because of these properties, the holding body and / or the connection device can be formed from this material in an advantageous manner.

Fig. 1

einen gegenüber einer praktischen Ausführungsform lediglich geringfügig vergrößert dargestellten Längsschnitt eines Ausführungsbeispieles des erfindungsgemäßen Druckspeichers;

Fig. 2

einen Längsschnitt lediglich eines Haltekörpers mit daran festgelegtem Stützkörper für das Ausführungsbeispiel von Fig. 1;

Fig. 3

einen gegenüber Fig. 2 stark vergrößerten Ausschnitt des in Fig. 2 mit III bezeichneten Bezirks und

Fig. 4

einen der Fig. 2 ähnlichen Längsschnitt, in dem ein abgewandeltes Beispiel der Verrastung des Stützkörpers am Haltekörper dargestellt ist.

The invention is explained in detail below with reference to the drawing. Show it:

Fig. 1

a comparison with a practical embodiment only slightly enlarged illustrated longitudinal section of an embodiment of the pressure accumulator according to the invention;

Fig. 2

a longitudinal section of only a holding body with it fixed support body for the embodiment of Fig. 1 ;

Fig. 3

one opposite Fig. 2 greatly enlarged section of the in Fig. 2 with III designated district and

Fig. 4

one of the Fig. 2 similar longitudinal section, in which a modified example of the locking of the support body is shown on the holding body.

The invention will be explained below with reference to the example of the use of the pressure accumulator for a system of urea injection. In Fig. 1 , which shows the embodiment of the pressure accumulator in its entirety, a memory housing is denoted by 2, which has the shape of a large cylindrical pot on the closed bottom 4, a flow opening 6 is located on the whole. The aligned on the central longitudinal axis 10 opening 6 allows the supply and removal of a first fluid, such as a urea-water solution, to or from the first compartment 8, which is located in the housing 2 adjacent to the bottom 4. One with the storage housing 2 screwed head portion 12 forms the fluid-tight closure of the upper, open end of the housing second

The head part 12 has an outer cover part 14 on which the screw connection with the housing 2 is formed and which may consist of a metallic material, for example of aluminum, as may also be the case with the housing 2. Alternatively, the cover part 14 may also be formed from a structurally stable plastic material. The cover part 14 has a central, concentric with the axis 10 opening 16. At a small distance from the opening 16, the cover part 14 inner wall parts in the form of a concentric to the axis 10 spherical cap 18. Within the cover part 14, the head part 12 has a holding body 20, with an integrally located thereon, the connecting means for the second fluid forming screw 22, which passes through the opening 16 of the cover member 14 and by means of which, in cooperation with a nut 24 of the holding body 20 within the lid part 14 is fixed. Through the screw neck 22, a central fluid channel 26 extends to fill a third subspace 28 with the working medium under bias pressure as the second fluid. A located within the channel 26 valve insert is not shown in the drawing.

The holding body 20 has the shape of a bell whose shell surrounds a fourth subspace 30 which adjoins the third subspace 28. The bell shell forms on its outer wall spherical surface parts 34 which define a clamping gap 36 for the anchoring region 38 located in the gap 36 of a separation membrane 40 between itself and the cap 18 of the cover part. The bladder formed from a plastic suitable for such pressure accumulators, such as butyl, forms the flexible separating membrane 40 between the first subspace 28 and the second subspace 54. The holding body 20 has an annular groove 42 between the end of the outer spherical surface part 34 and the screw neck 22, into which for particularly secure anchoring the separating membrane 40 engages an edge bead 44 surrounding its opening edge.

The holder body 20 forms with which located within the plane formed by the separating membrane 40 bubble cap, a holding portion 46 for anchorage of a projecting into the interior of the bladder support body 48. This is formed of a sufficiently structurally rigid plastic material, with glass fiber-reinforced polyarylamide IXEF ^® to be particularly well has proved suitable. How out Fig. 1 can be seen, the support body 48 has the shape of a body of revolution with spherical rounded, located at a distance from the bottom 4 of the housing 2 located lower end and surrounds adjacent to the fourth subspace 30 third subspace 28. The other, upper end 50 of the support body 48 fixed to the holding part 46 by means of a snap connection. As Fig. 1 In addition, the support body 48 is approximately V-shaped in longitudinal section and has lateral wall openings 52 for the passage of the working fluid to the second compartment 54, which adjoins the third compartment 28.

The details of the snap connection are the most obvious FIGS. 2 and 3 removable. As can be seen 46 recesses 56 and 60 are formed at a small distance from the end edge 56 of the holding member, in which the end portion of the support body 48 is receivable, wherein a radially inwardly projecting projection 62 of the support body 48 can be snapped into the recess 60. The holding body 20 is formed in the present example, as well as the support body 48 and located in the channel 26 of the nozzle 22 valve made of glass fiber reinforced polyarylamide IXEF ^® , so that the holding body 20 is formed therewith a support body 48 is a completely made of plastic unit.

In operation, when used for the urea injection, the first subspace 8 of the pressure accumulator by means of a pump with the urea-water solution filled until an upper value of the system pressure is reached and the pump shuts off. The accumulator pressure forces the metered injection storage medium into the system. When a lower pressure value is reached, the pump switches on again. If it should come to unwanted pressure excesses and a certain limit of the volume increase of the first subspace 8 is exceeded, the separation membrane 40 applies to the support body 48 and is thereby protected against overloading and damage.

The Fig. 4 shows a variant of the design of the snap connection, wherein the locking elements are now arranged on the inner wall of the holding member 46 of the holding body 20. As Fig. 4 shows, it is a recess 64 axially remote from the end edge 56 and a radially inwardly projecting, adjoining the end edge 56 projection 66. The counter-elements on the part of the support body 48 are formed by retaining fingers 68 which extend beyond the circumference of the opening Support body 48 are arranged distributed. When formed by individual locking fingers 68 counter elements, the preparation of the locking designed particularly simple and convenient.

Also at the in FIGS. 2 and 3 shown embodiment of the latching on the outside of the holding member 46 of the holding body 20, the counter-elements of the support body 48 may also be formed of individual, circumferentially distributed locking fingers.

Claims (19)

1. A pressure accumulator comprising compartments (8, 54, 28) arranged within a housing (2),

   - a first compartment (8) arranged between the housing (2) and a flexible separating diaphragm (40),

   - a second compartment (54) arranged between the separating diaphragm (40) and a support body (48), and

   - a third compartment (28) contained within the support body (48),

   - the first compartment (8) being able to be filled with a first fluid,

   - the second compartment (54) and the third compartment (28) being connected to one another such as to convey fluid and being able to be filled with a second fluid,

   - the first and the second compartment (8, 54) varying in their respective size as a result of movements of the separating diaphragm (40) as a function of the respective filling state,

   - the first fluid being a storage medium and the second fluid being a working medium, and

   - the second compartment (54) being enlarged when the storage medium is removed from the pressure accumulator and being reduced in size when the pressure accumulator is filled with storage medium,

   - characterised in that the support body is in the form of a rotating body with an approximately V-shaped longitudinal section and which is rounded and closed on the end facing the first compartment (8) and is provided with at least one side wall opening (52) as the point for passing through between the second and the third compartment (54; 28).
2. The pressure accumulator according to Claim 1, characterised in that the pressure accumulator is in the form of a hydropneumatic bladder accumulator for a gaseous working medium and/or a liquid storage medium.
3. The pressure accumulator according to Claim 1 or 2, characterised in that the pressure accumulator is made for filling with a storage medium in the form of a chemically corrosive fluid such as urea/water solution.
4. The pressure accumulator according to any of the preceding claims, characterised in that the support body (48) and separating diaphragm (40) are shaped and dimensioned such that the support body (48) forms a support for the separating diaphragm (40) at a volumetric size of the first compartment (8) which exceeds a definable limit value.
5. The pressure accumulator according to any of the preceding claims, characterised in that the housing (2) and the separating diaphragm (40) are shaped and dimensioned such that the separating diaphragm (40) at least partially adjoins the housing (2) when the first compartment (8) is completely emptied.
6. The pressure accumulator according to any of Claims 1 to 4, characterised in that the separating diaphragm (40) is shaped and dimensioned such that it is spaced apart from the support body (48) and from the housing (2) when the first compartment (8) is completely emptied.
7. The pressure accumulator according to any of the preceding claims, characterised in that the housing (2) has a head part (12) which forms the closure of the housing (2) adjacent to the second and/or third compartment (54, 28).
8. The pressure accumulator according to Claim 7, characterised in that there is a connection device (22) for the second fluid in the head part (12).
9. The pressure accumulator according to Claim 7 or 8, characterised in that there is provided on the head part (12) a retaining body (20) on which the opening edge of the separating diaphragm (40) is anchored.
10. The pressure accumulator according to Claim 9, characterised in that the retaining body (20) forms a retaining part (46) on which the support body (48) is arranged.
11. The pressure accumulator according to either of Claims 9 or 10, characterised in that the retaining body (20) is in form of a bell the jacket of which surrounds a fourth compartment (30) adjacent to the third compartment (28).
12. The pressure accumulator according to any of Claims 9 to 11, characterised in that the head part (12) has a cover part (14) which can be screwed to the housing (2) with inside wall parts in the form of a spherical cap (18) which is concentric to the axis (10) of the housing (2) and that within the cover part (14) the retaining body (20) is arranged such that between its outside wall in the form of spherical surface parts (34) and the inside wall parts of the cover part (14) a gap (36) is formed for accommodating an edge region (38) of the separating diaphragm (40) adjacent to the opening edge.
13. The pressure accumulator according to any of Claims 9 to 12, characterised in that in a region which is axially offset from its retaining part (46) in the direction of the connection device (22) the retaining body (20) has an annular groove (42) which has been machined into the outside wall and in which an edge bead (44) which surrounds the opening edge of the separating diaphragm (40) engages for the anchoring of the latter.
14. The pressure accumulator according to Claim 12 or 13, characterised in that the connection device has a screw fitting (22) which extends through an opening (16) of the cover part (14) which is concentric to the central axis (10), which fitting pulls the retaining body (20) against the inside wall of the cover part (14) by screwing to the cover part (14) and clamps the edge region (38) of the separating diaphragm (40) located in the gap (36).
15. The pressure accumulator according to any of Claims 10 to 14, characterised in that in the region of the retaining part (46) the retaining body (20) forms a circular cylinder on the edge region of which catch elements (58, 60) are formed which with counter-elements (62) on the support body (48) form a snap connection which anchors the latter.
16. The pressure accumulator according to Claim 15, characterised in that the catch elements on the outer wall of the retaining part (46) are offset from its end edge (56) and are formed by depressions (58, 60) of the outer wall of the retaining part (46) into which a bead-like projection (62) which protrudes radially to the inside can be snapped on the inside of the support body (48).
17. The pressure accumulator according to Claim 15, characterised in that the catch elements on the inside wall of the retaining part (46) are formed by a depression (64) which is axially spaced apart from its end edge (56) and a projection (66) which adjoins the end edge (56) and which protrudes radially to the inside, and said catch elements can be latched to counter-elements by catch fingers (68) which are distributed over the periphery of the opening of the support body (48).
18. The pressure accumulator according to any of the preceding claims, characterised in that the support body (48) is formed from plastic, preferably from glass fibre-reinforced polyarylamide IXEF^®.
19. The pressure accumulator according to any of Claims 9 to 18, characterised in that the retaining body (20) and/or the connection device (22) is formed from plastic, in particular glass fibre-reinforced polyarylamide IXEF^®.

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