Hydro storage

Abstract

Hydraulic accumulator, comprising a housing (1) and a movable partition (9) in the form of an elastomeric membrane separating a first media side, in particular fluid side (13), from a second media side, in particular gas side (11), the partition being fixed to the housing (1) at its circumferential edge (19) and having a valve part (31) in its central region which, in one of the possible deflections of the partition (9), closes an opening (15) of the housing (1) leading into the first media side (13), wherein the partition (9) is designed as a corrugated membrane having a plurality of troughs (37) and crests (35) which, starting from an initial state, move in a smoothing manner towards the first media side (13) in an actuated state, wherein a thickened edge bead (19) is provided at the circumferential edge of the corrugated membrane (9) for fixing it to the housing (1), characterized in thatthat the edge bulge (19) in the unactuated state of the wave membrane (9) is larger than the wave height of the waves (33), so that the edge bulge (19) projects axially beyond the adjacent wave crest (35) and beyond the imaginary partition surface (40) facing the gas side (11).

Description

[0001] The invention relates to a hydraulic accumulator, with a housing and a movable partition in the form of an elastomeric membrane separating a first media side, in particular a fluid side, from a second media side, in particular a gas side, which is fastened to the housing at its peripheral edge and has a valve part in its central region which closes an opening in the housing leading into the first media side during one of the possible deflections of the partition, wherein the partition is designed as a wave membrane which has a plurality of wave troughs and wave crests which, starting from an initial state, roll out and move smoothing in the direction of the first media side in an actuated state, wherein a thickened edge bead is provided on the peripheral edge of the wave membrane for fastening to the housing.

[0002] A hydraulic accumulator of this type is known from DE 41 31 524 A1. The diaphragm, made of a malleable material, has a roughly hemispherical shape when viewed from the side. The surface is smooth on both the outside and inside of the diaphragm, and a thickened rim is formed on the peripheral edge. This rim cooperates with a retaining device to secure the diaphragm in the housing.

[0003] The high flexibility required for favorable operating behavior in such a membrane leads to a relatively low wall thickness of the membrane material and thus a reduction in resistance to mechanical stresses occurring during operation.

[0004] GB 571 616 discloses a hydraulic accumulator with a shaft diaphragm. A thickened edge bead extends radially in the plane of the shaft diaphragm to be positively received between two housing parts of the hydraulic accumulator.

[0005] Based on this state of the art, the invention aims to provide a hydraulic accumulator of the type considered which is characterized by particularly favorable operating behavior.

[0006] According to the invention, this object is achieved by a hydraulic accumulator which has the features of patent claim 1 in its entirety.

[0007] According to the characterizing part of patent claim 1, an essential feature of the invention is that the edge bead is larger than the wave height of the waves in the unactuated state of the wave membrane, so that the edge bead projects axially beyond the adjacent wave crest and beyond the imaginary partition wall surface facing the gas side.

[0008] The partition wall has a plurality of wave troughs and wave crests which, starting from an initial state, roll out in an actuated state and move smoothingly towards the first media side, in particular the fluid side. In contrast to a smooth-surfaced membrane, a corrugated membrane of this type can be extended by stretching the folds of the wave structure, without the material actually having to stretch. Such a membrane behaves similarly to a bellows, which, by extending the folds, enables relatively large working strokes with small required deflection forces. Overall, the membrane is characterized by high flexibility even with greater wall thickness, resulting in favorable operating behavior despite its resistance to mechanical stress.It is preferably provided that the plurality of wave troughs and wave crests are arranged in at least one common plane in the said initial state.

[0009] In particularly advantageous embodiments, the partition in the form of a wave membrane has a sequence of waves concentrically surrounding the valve part, the wave crests of which define imaginary partition surfaces on both sides of the wave membrane, which are approximately flat in the non-actuated initial state. When such wave rings are formed, the membrane approaches a hemispherical shape when unrolling, i.e. a shape that is particularly advantageous in connection with accumulator housings in which the fluid side is delimited by a housing shell that has spherical surface parts. In preferred embodiments, a sequence of identically shaped waves arranged at equal radial distances from one another is provided.

[0010] With particular advantage, the arrangement can be such that waves with rounded wave crests and troughs are provided and that the wave crests located on the sides of the wave membrane define the imaginary partition surfaces.

[0011] The valve part can have a flat section that adjoins the wave crest of the innermost wave, which is located on the imaginary partition surface facing the fluid side. Therefore, when the diaphragm is fully deflected during operation, the valve part reaches the fluid-side housing opening practically simultaneously with the wave crest of the innermost wave located on the partition surface facing it.

[0012] In a modified embodiment, however, the arrangement can also be such that the flat section of the valve part adjoins the wave crest of the innermost wave, which is located on the imaginary partition surface facing the gas side. As a result, the valve part is set back from the partition surface facing the fluid side by a distance that corresponds to the wave height of the wave structure. This means that when the wave diaphragm is fully deflected, the wave crests adjacent to the valve part already come into contact with the housing wall before the valve part closes the fluid opening. With such a configuration, only a small residual volume of fluid remains in the housing before the final closing process, with the fluid still remaining within the innermost wave ring being displaced at the end of the closing process by the valve part moving closer to the opening.

[0013] In particularly advantageous embodiments, the section forming the valve part can have a flat closing surface with a central, shallow recess located therein on the side facing the fluid side of the housing, so that in the closed state there is no large-area contact of the valve part with the housing wall.

[0014] In particularly advantageous embodiments, the closing surface can be formed by a valve plate-like insert in the section of the valve part. This allows the actual valve body to be formed from a material particularly suitable for the valve function.

[0015] The invention is explained in detail below with reference to embodiments shown in the drawing.

[0016] They show: Fig. 1 shows a longitudinal section of an embodiment of the hydraulic accumulator according to the invention with the wave membrane in the unactuated state; Fig. 2 a plan view of the wave membrane of the embodiment in the unactuated state; Fig. 3 a cross-section of the unloaded wave membrane according to the section line III - III of Fig. 2; Fig. 4 a plan view of the shaft membrane in the unactuated state of a second embodiment of the hydraulic accumulator and Fig. 5 a cross section of the unactuated wave membrane of the second embodiment according to the section line V - V of Fig. 4.

[0017] The Fig. The embodiment of the hydraulic accumulator according to the invention shown in Figure 1 comprises a metallic accumulator housing 1. This consists, as viewed in the direction of Fig. 1, consists of an upper housing shell 3 and a lower housing shell 5, which abut one another along a seam 7. Along this seam 7, the two shells 3 and 5 can be welded together to form the housing 1, for example by means of an electron beam welding process. Within the housing 1, a corrugated membrane 9 forms a movable partition between a gas side 11 and a fluid side 13. On both the fluid side 13 and the gas side 11, the housing 1 has connection openings to which the hydraulic accumulator can be connected to pipes of a hydraulic system (not shown).

[0018] Of these openings, a fluid opening leading to the fluid side 13 as one media side is designated 15 and an opening leading to the gas side 11 as the other, second media side is designated 17. The shaft membrane 9 is secured within the housing 1 by means of a securing device which is designed in a manner known per se (cf. DE 41 31 524 A1) and interacts with a thickened edge bead 19 located on the peripheral edge of the shaft membrane 9. As in the known hydraulic accumulator mentioned, the securing device has two annular bodies, namely a steel ring 21 and a retaining ring 23, the latter of which is preferably formed by injection molding from a plastic, for example in the form of a polyarylamide with a glass fiber content.The steel ring 21 forms a border for the retaining ring 23 that rests against the housing wall and simultaneously covers the seam 7 of the welded joint, thus providing a shield against the welding heat from the plastic retaining ring 23. Facing the gas side 11, the retaining ring 23 has axial notches 25 distributed around its circumference. The peripheral edge of the retaining ring 23 facing the fluid side 13 forms a radially recessed annular channel 27 that forms a border for the edge bead 19 of the shaft diaphragm 9 that can be accommodated therein. Together with an annular shoulder 29 in the housing wall, the edge bead 19 and thus the shaft diaphragm 9 are securely anchored within the housing 1.

[0019] Like the Fig. 2 and Fig. 3, the round wave membrane 9, which has essentially the same wall thickness in the area of ​​the wave troughs 37 and wave crests 35 and is made of a synthetic rubber, such as nitrile butadiene (for example NBR20) or polyurethane, has a sequence of concentric, annular waves 33 between the outer edge bead 19 and a central, flat section 31 serving as a valve part, which waves are of the same design with rounded wave crests and wave troughs at equal radial intervals, of which the wave crests are designated 35 and the wave troughs 37 in the drawing, although not all of the wave crests and troughs are numbered.

[0020] In the drawing, in which the wave membrane 9 is shown in the non-actuated state, the wave membrane 9 forms a partition wall that runs in a plane, with imaginary lines connecting the wave crests 35 on both sides of the membrane 9 being designated here as imaginary partition wall surfaces 39 and 40. As Fig. 3 shows, the section 31 of the valve part, as a surface section free of waves 33, adjoins that wave crest 35 of the innermost wave 33, which is located on the imaginary partition surface 39 facing the fluid side 13, i.e., the section 31 is separated from the partition surface 39 only in the central part by a shallow depression 41. During the complete deflection of the wave membrane 9, the section 31 forming the valve part therefore only comes into contact with the housing wall surrounding the fluid opening 15 at the edge of the depression 41. As Fig. 3 shows, the axial height of the outer edge bead 19 is greater than the wave height of the waves 33, so that the edge bead 19 projects axially beyond the adjacent wave crest 35, that is, beyond the imaginary partition wall surface 40 facing the gas side 11.

[0021] The embodiment of Fig. 4 and Fig. 5 differs from the first embodiment in that the section 31 forming the valve part does not border the wave crest 35 of the innermost shaft 33 located on the fluid-side partition surface 39, but rather borders the wave crest 35 of the innermost shaft 33 remote from this partition surface 39. The section 31 thus forms a valve part that is set back from the partition surface 39 facing the fluid side 13 by a distance corresponding to the wave height. Furthermore, in this embodiment, the closing surface is formed by a valve insert 43 embedded in the section 31, in which the centrally located, shallow recess 41 is located.

[0022] This embodiment provides a particularly advantageous operating behavior in that, upon complete deflection of the wave membrane 9, the opening 15 remains open even when the wave crest 35 of the innermost wave 33 has moved toward the housing wall in a smoothing manner. The closure of the opening 15 only occurs when the recessed section 31 with the valve insert 43 subsequently overcomes the distance in a further deflection movement. This advantageously results in only a minimal residual volume of fluid remaining in the reservoir during the closing process. Fig. 5 also shows, the section 31 forms a type of valve plate which is not only set back from the imaginary fluid-side partition surface 39, but which also has a thickening rising over an inclined surface 45, by means of which a mechanical stabilization of the valve part 31 is formed.

[0023] In both embodiments, in the completely smoothed state, the separating membrane or partition wall 9 rests against the inside of the membrane housing in the direction of the fluid side 13, in that the wave crests and wave troughs of the fluid-impermeable membrane are rolled out (not shown).

Claims

[1] A hydraulic accumulator, comprising a housing (1) and a movable partition (9) in the form of an elastomeric membrane separating a first media side, in particular a fluid side (13), from a second media side, in particular a gas side (11), which is secured to the housing (1) at its peripheral edge (19) and has a valve part (31) in its central region which, upon one of the possible deflections of the partition (9), closes an opening (15) of the housing (1) leading into the first media side (13), wherein the partition (9) is designed as a wave membrane having a plurality of wave troughs (37) and wave crests (35) which, starting from an initial state, roll out in an actuated state and move in a smoothing manner towards the first media side (13), wherein a thickened edge bead (19) is provided on the peripheral edge of the wave membrane (9) for securing it to the housing (1), characterized bythat the edge bead (19) in the unactuated state of the wave membrane (9) is larger than the wave height of the waves (33), so that the edge bead (19) projects axially beyond the adjacent wave crest (35) and beyond the imaginary partition wall surface (40) facing the gas side (11). [2] Hydraulic accumulator according to claim 1, characterized by that the plurality of wave troughs (37) and wave crests (35) are arranged in at least one common plane (39, 40) in the initial state. [3] Hydraulic accumulator according to claim 1 or 2, characterized by that the partition in the form of a wave membrane (9) has a sequence of waves (33) concentrically surrounding the valve part (31), which waves, with their wave crests (35), define imaginary partition surfaces (39, 40) on both sides of the wave membrane (9), which are approximately flat in the unactuated initial state. [4] Hydraulic accumulator according to one of the preceding claims, characterized bythat a sequence of identically shaped shafts (33) arranged at equal radial distances from one another is provided. [5] Hydraulic accumulator according to one of the preceding claims, characterized by that waves (33) with rounded wave peaks (35) and troughs (37) are provided. [6] Hydraulic accumulator according to one of the preceding claims, characterized by that the valve part has a flat section (31) which adjoins the wave crest (35) of the innermost shaft (33), which is located on the imaginary partition surface (39) facing the fluid side (13). [7] Hydraulic accumulator according to one of the preceding claims, characterized by that the valve part has a flat section (31) which adjoins the wave crest (35) of the innermost wave (33), which is located on the partition surface (40) facing the gas side (11). [8] Hydraulic accumulator according to one of the preceding claims, characterized bythat the section (31) forming the valve part has, on the side facing the fluid side (13) of the housing (1), a flat closing surface with a central, flat recess (41) located therein. [9] Hydraulic accumulator according to one of the preceding claims, characterized by that the closing surface is formed by a valve plate-like insert (43) in the section (31) of the valve part. [10] Hydraulic accumulator according to one of the preceding claims, characterized by that the section (31) forming the valve part is located at a distance from the imaginary partition wall surface (39) facing the fluid side (13) that is at least preferably the same distance as the edge bead (19).

Images