EP2588761A1

EP2588761A1 - Pressure store

Info

Publication number: EP2588761A1
Application number: EP11726353.3A
Authority: EP
Inventors: Norbert Weber
Original assignee: Hydac Technology GmbH
Current assignee: Hydac Technology GmbH
Priority date: 2010-06-30
Filing date: 2011-06-17
Publication date: 2013-05-08
Anticipated expiration: 2031-06-17
Also published as: EP2588762B1; EP2588762A1; WO2012000617A1; US9133859B2; US20130126026A1; EP2588761B1; DE102010025627A1; WO2012000616A1

Abstract

A pressure store comprising sub-chambers (8, 54, 28) arranged in a housing (2), a first sub-chamber (8) arranged between the housing (2) and a flexible separating diaphragm (40), a second sub-chamber (54) arranged between the separating diaphragm (40) and a supporting body (48), and a third sub-chamber (28) encompassed by the supporting body (48), wherein the first sub-chamber (8) can be filled with a first fluid, wherein the second sub-chamber (54) and the third sub-chamber (28) are connected to one another in fluid-conducting fashion and can be filled with a second fluid, and wherein the first and the second sub-chamber (8, 54) vary in terms of their respective sizes as a result of movements of the separating diaphragm (40) as a function of the respective filling state, is characterized in that the first fluid is a storage medium and the second fluid is a working medium, and in that the second sub-chamber (54) is increased in size during the extraction of storage medium from the pressure store and is reduced in size during the filling of the pressure store with storage medium.

Description

accumulator

The invention relates to a pressure accumulator comprising sub-spaces arranged in a housing, a first sub-space arranged between the housing and a flexible separating diaphragm, a second sub-space arranged between the separating diaphragm and a supporting body, and a third sub-volume encompassed by the supporting body, wherein the first sub-space comprises a first sub-space the first fluid can be filled, wherein the second subspace and the third subspace are fluidly connected to each other and filled with a second fluid, and wherein the first and the second subspace vary by movements of the separation membrane depending on the respective Befül- lungszustand in their respective size.

Such a pressure accumulator is known from DE 101 13 41 5 A1. 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 separating element is anchored to the storage housing so as to form a seal, so that separate receiving spaces are formed on the outside and inside of the separating element. A central, continuous bore forms a passage for a storage medium leading to the inner 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 pressure accumulator is known from DE 38 10 509 C2. 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.

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 operational safety 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 used in vehicle technology to reduce the nitrogen oxides (NOx) emissions by injecting into the exhaust gas flow of internal combustion engines ,

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 characterizing part of claim 1, an essential feature of the invention is that the first fluid is a storage medium and the second fluid is a working medium, and that the second subspace increases upon removal of storage medium from the pressure accumulator and upon filling of the pressure accumulator with storage medium reduced. By the volumes of the second and the third subspace the male amount of working medium is determined. At a filling of the first subspace with storage medium, the flexible separation membrane is moved to the effect that the second subspace adjacent to the third subspace outside the support body is reduced. Accordingly, when a removal or decreasing Befül development of the first subspace with storage medium of 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 use of 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 at a fixed limit exceeding volume size of the first subspace, in other words at a maximum value for the recording medium to be recorded volume size, a support for the separation membrane forms.

Furthermore, it is advantageous if the housing and the separating membrane are shaped and dimensioned in such a way that the separating membrane rests against the housing at least partially 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 when pressure is exceeded. tions in the first and second subspace, in that the separation membrane or the storage bubble can abut the support body or on the housing and is thereby protected when pressure is exceeded against 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 expediently cup-shaped, wherein the first part is arranged on the bottom side. In Kopfteili 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 the material requirement for the formation of the pressure accumulator is reduced.

In particularly advantageous embodiments, the support body has the shape of a body of revolution, rounded at the end facing the first part space and formed closed and with at least one lateral wall opening as a passage point between the second and third partial space is provided. With such a design, the support body for the separation membrane or storage bubble can form a large-area support, so that the storage bubble, which lies practically free of creases when the pressure is exceeded, is optimally protected.

With regard to the design of the head part, the arrangement can be made with advantage so that the head part has a verschaubbares with the housing cover part with inner wall parts in the form of a concentric to the axis of the housing spherical cap, and that is arranged within the cover part of the holding body such that between the outer wall in the form of spherical surface parts and the inner wall parts of the cover part, a gap for receiving a bordering on the edge of the opening edge region of the separation membrane is formed. A particularly secure anchoring of the separating membrane can be achieved if the holding body has an annular groove machined into the outer wall in an area axially offset from its holding part in the direction of the connecting device, in which an edge bead surrounding the edge of its opening engages for anchoring the separating membrane.

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

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 kind the 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 locking elements on the inner wall of the holding member by one of the end edge axially remote recess and a radially inwardly projecting, adjoining the end edge projection may be latched with counter-elements of over the circumference of the opening of the support body vertei Lten 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 of 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.

The invention is explained in detail below with reference to the drawing. Show it: Fig. 1 shows 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 shows a longitudinal section of only one holding body with supporting body fixed thereto for the embodiment of FIG. 1; FIG.

Fig. 3 is a comparison with FIG. 2 greatly enlarged detail of FIG.

2 with III designated district and

FIG. 4 shows a longitudinal section similar to FIG. 2, in which a modified example of the latching of the supporting body on the holding body is shown.

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 whole, 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. A screwed to the storage housing 2 head part 1 2 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 slight distance from the opening 16, the cover part 14 has inner wall parts in the form of a spherical cap 18 concentric with the axis 10. Within of the cover part 14, the head part 1 2 a holding body 20, with an integrally located thereon, the connection means for the second fluid forming screw 22, which passes through the opening 1 6 of the cover member 14 and by means of which, in cooperation with a nut 24 of the holding body 20th is set within the lid part 14. By the

Screw socket 22 extends a central fluid channel 26 to fill a third subspace 28 with the standing under bias pressure working fluid as a 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 of the separation membrane 40 engages an edge rim 44 surrounding its opening edge.

The holder body 20 forms with which located within the bran by the Trennmem- 40 formed 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 ^® as has proved particularly well. As can be seen from FIG. 1, the support body 48 has the shape of a rotation body with a spherically rounded, closed lower end situated at a distance from the bottom 4 of the housing 2 and surrounding one The other, upper end 50 of the support body 48 is on Haltetei l 46 by means of a

Snap connection set. As FIG. 1 also shows, 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 partial space 54, which adjoins the third partial space 28.

The details of the snap connection can be seen most clearly in Figures 2 and 3. 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 is filled by means of a pump with the urea-water solution 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 there are unwanted pressure violations and a certain

Limit value 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. Fig. 4 shows a variant of the design of the snap connection, wherein the locking elements now on the inner wall of the holding part 46 of the Holding body 20 are arranged. As shown in FIG. 4, this 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 holding fingers 68, the are distributed over the circumference of the opening of the support body 48. When formed by individual locking fingers 68 counter elements, the preparation of the locking designed particularly simple and convenient. Also in the embodiment shown in Figures 2 and 3, the latching on the outside of the holding member 46 of the holding body 20, the counter-elements of the support body 48 may be formed of individual, circumferentially distributed locking fingers.

Claims

P a n t a n s p r e c h e

Pressure accumulator comprising partial chambers (8, 54, 28) arranged in a housing (2),

a first part (8) arranged between the housing (2) and a flexible separating membrane (40),

a between the separation membrane (40) and a support body (48) arranged second subspace (54), and

a third subspace (28) encompassed by the support body (48), wherein the first subspace (8) can be filled with a first fluid, wherein the second subspace (54) and the third subspace (28) are connected to one another in fluid-conducting manner and with a second one Fluid are fillable, and

wherein the first and the second partial space (8, 54) vary in their respective size as a result of movements of the separating membrane (40) as a function of the respective filling state,

characterized in that the first fluid is a storage medium and the second fluid is a working medium, and

- That the second subspace (54) increases upon removal of storage medium from the accumulator and reduced when filling the pressure accumulator with storage medium.

Pressure accumulator according to claim 1, characterized in that the pressure accumulator is designed as a hydropneumatic bladder accumulator for a gaseous working medium and / or a liquid storage medium.

Pressure accumulator according to claim 1 or 2, characterized in that the pressure accumulator for filling a storage medium in the form of a chemically aggressive fluid, such as urea-water solution is formed.

4. Pressure accumulator according to one of the preceding claims, characterized in that the support body (48) and the separation membrane (40) are shaped and dimensioned such that the support body (48) at one ner a definable limit exceeding volume size of the first subspace (8 ) forms a support for the separation membrane (40).

5. Pressure accumulator according to one of the preceding claims, characterized in that the housing (2) and the separation membrane (40) are shaped and dimensioned such that the separation membrane (40) at a complete emptying of the first subspace (8) at least partially on the housing (2).

6. Accumulator according to one of claims 1 to 4, characterized in that the separating membrane (40) is shaped and dimensioned such that they at a complete emptying of the first subspace (8) spaced from the support body (48) and spaced from the housing (2) is arranged. 7. Pressure accumulator according to one of the preceding claims, characterized in that the housing (2) to the second and / or third subspace (54, 28) adjacent, the closure of the housing (2) forming the head part (12). 8. Pressure accumulator according to claim 7, characterized in that in

Head part (1 2) is provided a connection means (22) for the second fluid.

9. Pressure accumulator according to claim 7 or 8, characterized in that on the head part (12) a holding body (20) is provided, on which the opening edge of the separating membrane (40) is anchored.

10. Pressure accumulator according to claim 9, characterized in that the holding body (20) forms a holding part (46) on which the supporting body (48) is arranged.

1 1. Pressure accumulator according to one of claims 9 to 1 0, characterized in that the holding body (20) has the shape of a bell whose bell mantle surrounds a third subspace (28) adjacent fourth subspace (30).

1 2. Pressure accumulator according to one of the preceding claims, characterized in that the supporting body (48) is a rotational body, rounded at the first part of the space (8) facing the end and closed and formed with at least one wall opening (52) as a passage point between the second Subspace (54) and third subspace

(28) is provided.

13. Pressure accumulator according to one of claims 9 to 12, characterized in that the head part (1 2) a with the housing (2) verschraubba- res cover part (14) with inner wall parts in the form of an axis (10) of the housing (2). concentric spherical cap (18), and that within the cover part (14) of the holding body (20) is arranged such that between the outer wall in the form of spherical surface parts (34) and the inner wall parts of the cover part (14) has a gap (36) for the Recording of an edge area adjacent to the opening edge

(38) of the separation membrane (40) is formed.

14 has pressure accumulator according to one of claims 9 to 1 3, characterized in that the holding body (20) in one of its holding part (46) in the direction of the connecting device (22) axially offset region incorporated in the outer wall annular groove (42) into the for the anchoring of the separating membrane (40) engages a rim wu Ist (44) surrounding its opening edge.

1 5. Accumulator according to claim 1 3 or 14, characterized in that the connection device has a screw socket (22) which passes through a central axis (10) concentric opening (16) of the cover part (14) and by screwing with the cover part (14) pulls the holding body (20) against the inner wall of the cover part (14) and clamps the edge region (38) of the separating membrane (40) located in the gap (36).

16. Pressure accumulator according to one of claims 10 to 1 5, characterized in that the holding body (20) in the region of the holding part (46) forms a circular cylinder, at its edge region locking elements (58, 60) are formed, which with counter elements ( 62) on the support body (48) form a snap-in connection anchoring this.

1 7. Accumulator according to claim 16, characterized in that the latching elements on the outer wall of the holding part (46) of the end edge (56) offset and by recesses (58, 60) of the outer wall of the

Holding parts (46) are formed, in which a bead-like, radially inwardly projecting projection (62) on the inside of the support body (48) can be snapped. 18. Pressure accumulator according to claim 16, characterized in that the latching elements on the inner wall of the holding part (46) by one of its end edge (56) axially remote recess (64) and a radially inwardly projecting, adjoining the end edge (56) Projection (66) are formed, which with counter-elements in the form of over the circumference of the opening of the support body (48) distributed latching fingers

(68) are latched.

19. Pressure accumulator according to one of the preceding claims, characterized in that the supporting body (48) is formed from plastic, preferably made of glass fiber reinforced polyarylamide IXEF ^® .

20. Pressure accumulator according to one of claims 9 to 19, characterized in that the holding body (20) and / or the connection device (22) made of plastic, in particular glass fiber reinforced polyarylamide IXEF ^® , is formed.