EP4168680A1

EP4168680A1 - Piston accumulator

Info

Publication number: EP4168680A1
Application number: EP21762658.9A
Authority: EP
Inventors: Peter Kloft; Jens Holger Köhne
Original assignee: Hydac Technology GmbH
Current assignee: Hydac Technology GmbH
Priority date: 2020-08-27
Filing date: 2021-08-11
Publication date: 2023-04-26
Also published as: WO2022043063A1; US20240011510A1; DE102020005257A1; CN220667962U; JP2023538738A

Abstract

The invention relates to a piston accumulator, comprising an accumulator housing (10) and a separating piston (12), which can be moved longitudinally in the accumulator housing (10) and which separates two media chambers (14, 16) from each other, characterized in that an end-position damping means (28) is provided between the separating piston (12) and the accumulator housing (10), which end-position damping means has at least one gap (66, 72), which gap constricts with increasing movement of the separating piston (12) toward its end position and thus builds up a flow resistance that inhibits the movement of the separating piston (12), and which gap is formed at least in one of the adjacent end faces (30, 56) of the separating piston (12) and of the accumulator housing (10) as a recess (64, 78).

Description

piston accumulator

The invention relates to a piston accumulator with an accumulator housing and a separating piston which can be moved longitudinally in the accumulator housing and which separates two media chambers from one another.

One of the main tasks of hydraulic accumulators, such as piston accumulators, is, among other things, to absorb a certain volume of pressurized fluids in a hydraulic system and to return them to the system when called up. In addition to piston accumulators, bladder accumulators, diaphragm accumulators, but also weight and spring-loaded accumulators are regularly used as hydraulic accumulators. A large number of tasks can be implemented with such hydraulic accumulators, such as energy storage, shock, vibration and pulsation damping, energy recovery (recuperation) and volume flow compensation.

DE 100 57 746 A1 discloses a hydraulic accumulator in the form of a piston accumulator, with an accumulator housing and with at least one gas space arranged therein as one media space and a fluid or liquid space as the other media space. The media spaces mentioned are separated from each other by a piston-like separating element, at least one of these media chambers being able to be filled with a pressure medium, such as hydraulic fluid, via a valve control unit having at least one switching valve, and being at least partially emptied by it during operation. In the known solution, the valve control unit is an integral part of a solid control block which, as part of the accumulator housing, is connected to the accumulator housing at the end thereof.

In particular with high dynamics in the operation of the piston accumulator and with rapid emptying processes on the liquid side of the accumulator, the separating piston can hit hard or hit the massive closing part of the accumulator housing in the form of the control block under the influence of the gas pre-filling pressure in one media chamber. so that damage to the accumulator housing and/or the separating piston is to be expected at least during long-term operation of such a piston accumulator, which can reduce the service life of such hydraulic accumulators, with the result that they often have to be exchanged for new accumulators.

In the context of non-generic suspension cylinders, such as hydropneumatic piston-cylinder arrangements (DE 10 201 1 010 070 AI), it has already been proposed to fix a plate-shaped partition body in a stationary manner in a cylinder housing with a piston rod arranged therein to be longitudinally movable for the purpose of damping the piston rod movement, which is equipped with a damping diaphragm is provided as a damping device; Even if this damping diaphragm, as also shown, is integrated directly into the piston of the piston rod, the manufacturing effort and thus the costs are increased with regard to the additional valve technology to be introduced. It has also been shown that due to the constant throttle cross sections of the damping orifice, adequate damping is not always guaranteed for every operating state. Proceeding from this state of the art, the object of the invention is to create an improved piston accumulator solution that can be implemented reliably in operation with little manufacturing effort and leads to good damping results even with high kinetic energy of the separating piston. A pertinent task is solved by a piston accumulator with the features of patent claim 1 in its entirety.

An essential special feature of the invention is accordingly that end position damping is provided between the separating piston and the accumulator housing, which has at least one gap which narrows with increasing movement of the separating piston towards its end position and in this way builds up a flow resistance which inhibits the movement of the separating piston and which is introduced as a depression at least in one of the adjacent end faces of the separating piston and accumulator housing. By means of the gap throttled fluid guidance when moving the separating piston in the direction of its lower stop position, a functionally reliable effective damping is achieved, which has no equivalent in the prior art. As a result of the gap reduction, the movement of the separating piston in the direction of its stop position is increasingly dampened with increasing flow resistance, so that even with high movement dynamics for the separating piston, unintentional impacts on the associated parts of the accumulator housing are avoided.

In a particularly preferred embodiment of the piston accumulator according to the invention, it is provided that the gap is an annular gap that includes a media opening that connects the interior of a media space with the environment in a media-carrying manner, in particular with media-carrying components of a technical system, such as a hydraulic system. In this way, fluid or liquid can be discharged centrally via the media opening, such as hydraulic oil, from the reservoir, so that the separating piston with its sealing system is centrally exposed to actuation and movement forces, which helps to relieve the sealing and guide band system for the separating piston. This not only applies when the accumulator is emptied, but also plays a central role when high-pressure fluid from a hydraulic system flows through the media opening into the lower liquid-carrying media chamber and flows into the accumulator, pushing the separating piston upwards in the direction of the gas supply in one Media space presses when increasing the gas preload. The gap preferably opens out in the direction of the media opening and is delimited on the outer circumference by wall parts of the accumulator housing and/or the separating piston. The annular gap, which can also be segmented into partial areas on the circumferential side, allows the fluid to flow out of the piston accumulator in the direction of the media opening unhindered, which counteracts an improved damping effect.

Provision is preferably made for the gap width to be constant when the separating piston strikes the adjacent accumulator housing, with the gap being limited by mutually parallel, adjacent, end-face wall parts of the separating piston and accumulator housing. In this way, relatively large volumes of fluid can also be discharged from the reservoir via the gap without the fluid being subject to high thermal crushing stress.

However, it is particularly preferred in a piston accumulator according to the invention that the gap width decreases continuously in the direction of the media opening. In this way, when the separating piston moves into its lower stop position, there is an increasing gap width reduction, which results in particularly good damping values, which progressively dampen the movement of the separating piston, whereas a constant gap width leads to a more linear damping behavior.

The gap is preferably made as a depression in the end wall of the separating piston, with the possibility also of making the depression in the end wall of the accumulator housing adjacent to the separating piston or, if possible, of providing a mirror-symmetrical gap depression both in the separating piston and in the accumulator housing on their adjacent end walls.

In order to achieve a defined stopping behavior of the separating piston, which accommodates an optimization of the outflow behavior of the fluid from the gap, it is preferably provided that the separating piston, while limiting the gap, can be moved with its piston parts in at least one of its end positions, in particular in the form of the lower end position. ßenumfangsseitig and / or inner circumference side goes to stop the storage housing. Any stop for the separating piston that runs on the inner circumference can be provided with openings that connect the gap depression with the media opening in the reservoir, so that, throttled in this way, as part of the damping device, fluid can flow out of the other media space.

It has also proven to be advantageous to provide for the separating piston to have a pin-like extension on its free end face facing the media opening, which dips into the media opening as part of the end-position damping when it becomes effective. A further throttling of the fluid flow, starting from the respective gap depression, in the direction of the media opening can be provided via the mentioned extension, which leads to improved damping results. In a particularly preferred embodiment of the piston accumulator according to the invention, it is provided that the continuously decreasing gap size is at least partially formed by a cone in the separating piston. In particular with the convex configuration of the course of the gap, there is a harmonious flow behavior and undesired occurrences of cavities during operation of the accumulator are avoided in the area of the gap reduction in any case.

From a manufacturing point of view, it has proven to be advantageous for a piston accumulator to provide that the accumulator housing is formed from at least one, preferably cylindrical, housing wall and one, preferably cylindrical, closing part which has the media connection and is preferably screwed into the housing wall. In this way, a reliably functioning piston accumulator that has reliably functioning end position damping can be implemented with few components in a simple manner in terms of production technology. It is also of particular importance for the solution according to the invention that when the separating piston moves to its lower stop position, in which it is seated, for example, on the outer contact ring of the housing cover, the fluid-carrying bore in the housing cover is not closed in any case, i.e. remains open, so that in this respect Fluid can flow undisturbed from the gap-shaped damping chamber into the oil-side connection hole.

A piston accumulator according to the invention is explained in more detail below with reference to exemplary embodiments according to FIGS.

1 shows, in longitudinal section, the lower part of a first exemplary embodiment of a piston accumulator according to the invention in one of its operating positions. The piston accumulator has a separating piston 12 that can be moved longitudinally in a cylindrical accumulator housing 10 and that As seen in FIG. 1, a lower media space 14 is separated from an upper media space 16 . The upper, one media chamber 16 is used to store a working gas, such as nitrogen gas, whereas the lower, other media chamber 14 is used to hold a liquid, in particular in the form of hydraulic oil.

Such piston accumulators are freely available on the market in a large number of embodiments, so that their structure will only be discussed in detail insofar as it relates to the invention. The separating piston 12 is provided with guide bands 18 and sealing ring arrangements 20, is arranged in the accumulator housing 10 in its operating installed position shown so that it can be moved longitudinally and therefore moved up and down. The cylindrical storage housing 10 is closed media-tight at the top, for example in a way as shown in the generic DE 100 57 746 A1. In the area of its opening 22 on the bottom, the accumulator housing 10 is closed by means of a cylindrical closing part 24, which is inserted into the housing wall 25 via the opening 22 on the bottom, in particular is screwed into the lower end of the accumulator housing 10 via a threaded section 26. Furthermore, the solution according to the invention has end position damping 28, which ensures that the separating piston 12 is braked in the event of particularly rapid downward movements and, in particular, that the separating piston 12 does not hit the end part 24, which can lead to material damage.

On its end face 30 facing the separating piston 12, the closing part 24 is designed as a flat boundary wall, which opens out on the inner circumference without protruding into a media opening 32, which is designed as a central fluid channel in the longitudinal direction of the accumulator housing 10, the lower media space 14 with parts of a not shown hydraulic system connects. For this purpose, the fluid channel 32 at its lower Outlet point on an internal thread 34 for the purpose of connecting a corresponding fluid or liquid line of the hydraulic system. On the outer peripheral side, the planar boundary wall 30 of the closing part 24 transitions into a cylindrical contact wall 36 which accommodates a sealing ring 38 at the head end, which is in contact with the inner wall of the accumulator housing 10 in a sealing manner. On the foot side, the contact wall 36 is then followed by the external thread 26 of the closing part 24 as part of the thread section 26 .

Starting from the thread section 26, formed by the external thread of the closing part 24 and the associated internal thread of the accumulator housing 10, which is arranged at the thinnest point 42 of the accumulator housing 10 in its lower region, the wall thickness of the accumulator housing 10 increases in steps 44, with one average wall thickness 46 is reached in the area of the adjacent contact wall 36 of the closing part 24 and the wall thickness area 48 with the greatest wall thickness forms the running surface for the separating piston 12 in this lower area on the inside circumference. The transition point from the middle 46 to the greatest 48 wall thickness area forms an annular boundary surface 50, which specifies the maximum engagement area of the closure part 24 in the accumulator housing 10, with the boundary wall 30 of the closure part 24 not necessarily being in contact with the rounded, tapering contact surface 50 of the accumulator housing, as shown 10 needs to come.

The separating piston 12, which is provided with a recess 54 to increase the gas volume that can be used, has at its lower end 56 an outer limiting ring 58 and an inner cylindrical contact area 60 projecting in the manner of a peg. The limiting ring 58 goes over the outer peripheral side in one piece into the outer guide wall 62 of the separating piston 12 and its free end face 59 lies in a plane with the free end face 61 of the cylindrical contact area 60, which in turn is integral Is part of the separating piston 12 and is arranged parallel to the boundary wall 30 of the closing part 24 in each travel position of the separating piston 12 .

The outer diameter of the limiting ring 58 is slightly smaller than the outer diameter of the end part 24 in the area of its cylindrical contact wall 36, so that when the separating piston 12 is placed on the end part 24, an optimal, gentle introduction of force is achieved. The outer diameter of the cylindrical contact area 60 is in turn selected to be slightly larger than the free diameter of the media opening 32 or the central channel, so that there is central support when the force is introduced by the counterpart closure part 24 when it is placed on as described above. Between the outer boundary ring 58 and the inner contact area 60, in the free, downward-facing end wall 56 of the separating piston 12, there is a recess 64 of the same depth, which forms an annular gap 66 in the separating piston 12, which is concentric to the longitudinal axis 68 of the accumulator housing 10 runs and is part of the cushioning 28.

When the recess 64 is made in the separating piston 12, the outer boundary ring 58 and the inner cylindrical, socket-like contact area 60 remain free, and when the separating piston 12 is in the lowest position, they are in contact with the adjacent, flat boundary wall 30 of the end part 24. In the direction of this In the lowest travel position, the limiting ring 58, seen in the axial travel direction parallel to the longitudinal axis 68 of the accumulator housing 10, moves over the transition between the middle 46 and greatest 48 wall thickness area of the accumulator housing 10. The recess 64 in the form of the annular space, which has the same volume, has a space formed by the separating piston 12 Floor 70, which runs flat, parallel to the free end faces 59, 61 of the limiting ring 58 and the contact area 60. If the separating piston 12 moves downwards on its liquid side 14 during a removal process under the preload pressure of the working gas 16, which can occur dynamically at correspondingly high speeds, a gap opening, formed from the adjacent wall parts of the end part 24 and the cylindrical contact area 60, narrows noticeably, which increasingly leads to the build-up of flow resistance, which inhibits the movement of the separating piston 12 in the direction of the closing part 24 in the sense of end position damping, which is correspondingly promoted by the depression 64 in the separating piston 12 and a material-tiring impact of the separating piston 12 on the stationary arranged closing part 24 of the accumulator housing 10 as part of the same is prevented.

The pertinent throttling process via the free gap opening is shown in FIG. If the downward movement is complete and the separating piston 12 is in contact with the closing part 24, a residual amount of liquid remains in the annular recess 64 as part of the annular gap in the separating piston 12, which then forms a kind of hydrodynamic eager that allows an unobstructed, low-cavitation afterflow of Fluid is allowed in the opposite direction from the side of the media opening 32 as soon as the separating piston 12 lifts off the closing part 24 of the accumulator housing 10 under an increased fluid pressure with a simultaneous increase in the gas preload, i.e. seen in the viewing direction of FIG. 1, moves into an upper operating position.

In an embodiment that is not shown, it is also possible to introduce at least one throttle bore into the cylindrical contact area 60 of the separating piston 12; opens with its other free end in the annular space of the recess 64 in the separating piston 12 and thus serves as part of a changing gap geometry.

FIG. 2 shows a longitudinal section through the lower part of a second embodiment of the piston accumulator according to the invention in its lower end position, which differs from the first embodiment according to FIG. 1 as follows:

In the downward end wall 56 of the separating piston 12 there is a recess 64 of constant depth which is surrounded by the outer limiting ring 58 and forms a disk-shaped, cylindrical gap 66 in the separating piston 12 which is part of the end position damping 28 . The gap 66 is delimited in the radial direction by the radially inner side wall 74 of the outer limiting ring 58 and runs concentrically to the longitudinal axis 68 of the accumulator housing 10. The recess 64 in the separating piston 12 has a base 70 formed by the separating piston 12, which runs flat and parallel to the free end face 59 of the outer limiting ring 58 of the separating piston 12 runs.

The closing part 24 has at its upper end 30, seen in the radial direction, a further outer delimiting ring 76, which is aligned coaxially to the longitudinal axis 68 of the piston accumulator and the free end face 30 of which lies in an imaginary plane which is aligned perpendicular to the longitudinal axis 68 of the piston accumulator . The further outer delimiting ring 76 merges on the outer circumference in one piece into the outer contact wall 36 of the end part 24 . An annular depression 78 with a constant depth, which is surrounded by the further outer limiting ring 76 and forms a disk-shaped, cylindrical gap 72 in the closing part 24 and forms part of the end-position damping 28 , is introduced into the upward-pointing end wall 30 of the closing part 24 . The disc-shaped gap 72 is delimited in the radial direction by the radially inner side wall 80 of the further outer delimiting ring 76 of the closing part 24 , which is aligned with the radially inner side wall 74 of the outer delimiting ring 58 of the separating piston 12 . The depression 78 in the closing part 24 has a base 82 formed by the closing part 24, which runs flat, parallel to the free end face 30 of the further outer boundary ring 76 and merges into the fluid channel 32 in a radially inward direction without protruding.

The depression 64 of the separating piston 12 has a smaller depth than the depression 78 of the closing part 24 .

In the lower end position of the separating piston 12 shown in Fig. 2, only the mutually facing end faces 30, 59 of the limiting rings of the separating piston 12 and the closing part 24 are in contact with one another, with the depressions 64, 78 of the separating piston 12 and the closing part 24 remaining at a distance from one another . As a result, the disc-shaped total gap 66, 72 formed in the lower end position of the separating piston 12 by the depressions 64, 78 in the separating piston 12 and closing part 24 is permanently in fluid-conducting connection with the fluid channel 32.

In this way, when the accumulator is emptied on its liquid side 14 with a simultaneous downward movement of the separating piston 12, there is a rapid flow of fluid in this area, which leads to a negative pressure in the gap 66, 72, which is open towards the inside, which on the one hand accelerates the downward movement of the separating piston 12, on the other hand but also carries with it more or less dispersed gas fractions in the liquid, which would otherwise oppose effective damping due to their compressible behavior. 3 shows, in longitudinal section, the lower part of a third exemplary embodiment of the piston accumulator according to the invention in one of its operating positions. A partial longitudinal section of the separating piston 12 of the third exemplary embodiment of the piston accumulator from FIG. 3 in the region of its recess 64 is shown in FIG. The third exemplary embodiment of the piston accumulator differs from the first exemplary embodiment according to FIG. 1 as follows:

A truncated cone-shaped recess 64 , which is surrounded by the outer limiting ring 58 and forms a corresponding gap 66 in the separating piston 12 , which forms part of the end-position damping 28 , is introduced into the downward-pointing end wall 56 of the separating piston 12 . The indentation 64 has the maximum depth directly adjacent to the radially inner side wall 74 of the outer limiting ring 58 of the separating piston 12 in the region of a linear and circular edge 84 in the transition between the radially inner side wall 74 of the outer limiting ring 58 and the bottom 70 of the Depression 64. The depression 64 has the minimum depth in the area of a central and flat circular surface 86, which is aligned concentrically to the longitudinal axis 68 of the piston accumulator, in an imaginary plane aligned perpendicular to the same. Formed in this way, the outer limiting ring 58 of the separating piston 12 protrudes in the axial direction toward the end part 24 the central circular surface 86, which in turn protrudes beyond the circular edge 84 in the transition between the bottom 70 of the recess 64 and the radially inner side wall 74 of the outer limiting ring 58. Starting from the edge 84 in the transition between the base 70 of the recess 64 and the radially inner side wall 74 of the outer limiting ring 58, the base 70 of the recess 64 extends in the direction of the closing part 24 and the longitudinal axis 68 of the piston accumulator with a constant slope, tapering to the central circular area 86 and merges into it. FIG. 3 shows the piston accumulator in a state in which the separating piston 12 is arranged at a slight distance from the closing part 24 . When the separating piston 12 moves in the direction of the closing part 24 in this state--just as in the first exemplary embodiment according to FIG.

The diameter of the central circular surface 86 is smaller than the inner diameter of the fluid channel 32 of the closure part 24, so that the separating piston 12 arranged in its lower end position is in contact with the flat end face 30 of the closure part 24 exclusively with its outer limiting ring 58, with the separating piston 12 in the region of its depression 64 is spaced apart from the closing part 24. As a result, the gap 66, which is also delimited in the lower end position of the separating piston 12 by the depression 64 in the separating piston 12 and the end face 30 of the closing part 24, is permanently in fluid-conducting connection with the fluid channel 32 On its radially outer side, the gap 66 runs in the direction of the fluid channel 32 due to its sloping upper side, seen in a longitudinal section, in a wedge shape.

5 shows a longitudinal section through the lower part of a fourth exemplary embodiment of the piston accumulator according to the invention in its lower end position, which differs from the third exemplary embodiment according to FIG. 3 as follows:

In addition to the truncated cone-shaped depression 64 in the end wall 56 of the separating piston 12, which points downwards, the closing part 24 has at its upper end, seen in the radial direction, a further outer limiting ring 76 which is aligned coaxially with the longitudinal axis 68 of the piston accumulator and whose free end face 30 on a fictional level lies, which is aligned perpendicular to the longitudinal axis 68 of the piston accumulator. The radially inner side wall 80 of the further outer delimiting ring 76 is aligned with the radially inner side wall 74 of the delimiting ring 58 of the separating piston 12. The further outer delimiting ring 76 merges integrally into the outer contact wall 36 of the closing part 24 on the outer peripheral side. The end of the wall 88 of the fluid channel 32 facing the lower media chamber 14 extends in the axial direction up to the imaginary plane in which the end face 30 of the further outer delimiting ring 76 lies. Between the further outer boundary ring 76 and the end of the wall 88 of the fluid channel 32 facing the lower media space 14, a conically tapering indentation 78 is made in the upward-pointing end wall 30 of the closing part 24, which forms a corresponding annular gap 72, which forms part of the end-of-stroke cushioning 28 is. The indentation 78 has the maximum depth directly adjacent to the radially inner side wall 80 of the further outer boundary ring 76 of the closing part 24 in the area of a linear and circular edge 90 in the transition between the radially inner side wall 80 of the further outer boundary ring 76 and the floor 82 of the depression 78. The depression 78 has the minimum depth in a direct connection to the end of the wall 88 of the fluid channel 32 facing the lower media space 14. Starting from the edge 90 in the transition between the radially inner side wall 80 of the further outer boundary ring 76 and the base 82 of the recess 78, the base 82 of the recess 78 extends conically in the direction of the separating piston 12 and the longitudinal axis 68 of the piston accumulator with a constant slope the end of the wall 88 of the fluid channel 32 facing the lower media space 14, into the inner wall of which the base 82 merges.

The maximum depth of the depression 78 of the closing part 24 is greater than the maximum depth of the depression 64 of the floating piston 12. If the separating piston 12, as shown in Fig. 5, is arranged in its lower end position, it is only in contact with the further outer limiting ring 76 of the closing part 24 with its outer limiting ring 58, the separating piston 12 being spaced in the region of its recess 64 from the closing part 24. As a result, the overall gap 66, 72, which is also delimited in the lower end position of the separating piston 12 by the depressions 64, 78 in the separating piston 12 and closing part 24, is permanently in fluid-conducting connection with the fluid channel 32. The gap 66 runs from its radially outer side , 72 wedge-shaped in the direction of the fluid channel 32 due to its sloping top and bottom, seen in longitudinal section.

It has been shown that this conical double-gap arrangement leads to very good damping properties under high thermal stress, since the fluid that is thermally stressed by the movement of the separating piston 12 enables heat to be introduced in both directions, i.e. both to the separating piston 12 and to the closing part 24 of the storage enclosure 10.

6 shows a longitudinal section through the lower part of a fifth exemplary embodiment of the piston accumulator according to the invention in its lower end position, which differs from the first exemplary embodiment according to FIG. 1 as follows:

The constant depth recess 64 in the downwardly directed end 56 of the floating piston 12 is provided between the outer limit ring 58 and a central extension 92 in the form of a peg-like downward projection. The central projection 92 projects beyond the outer limiting ring 58 in the axial direction. The axial height of the central projection 92 preferably corresponds approximately to the axial wall thickness of the bottom 94 of the separating piston 12. The free end face 96 of the central projection 92 is designed as a flat circular surface and lies in a fictitious plane aligned perpendicularly to the longitudinal axis 68 of the piston accumulator. Viewed in the axial direction, the central projection 92 is cylindrical between the base 70 of the recess 64 of the separating piston 12 and its central region, whereupon the central projection 92 tapers conically from its central region in the direction of its flat, free end face 96.

In order to move the central projection 92 of the separating piston 12 into and out of the closing part 24, the fluid channel 32 of the closing part 24 is designed in such a way that its inner diameter widens in an end region facing the lower media space 14 in the direction of the lower media space 14, forming a conical shape widening intermediate region 100. The axial height of the inner diameter enlargement 98 of the fluid channel 32 is greater than the axial distance between the end face 59 of the outer limiting ring 58 of the separating piston 12 and the free end face 96 of the central projection 92. As a result, when the separating piston 12 is arranged in its lower End position, in which the outer limiting ring 58 of the separating piston 12 is in contact with the flat end face 30 of the closing part 24 in the sense of a stop, the free end face 96 of the central projection 92 is spaced apart in the axial direction, forming a gap from the conically widening intermediate area 100 of the fluid channel 32 of the closing part 24 is arranged. In addition, the radial width of the inner diameter enlargement 98 of the fluid channel 32 is greater than the largest outer diameter of the central projection 92, forming a gap.

In this way, there are different effective gap areas for the end position damping 28. If the separating piston 12, as shown in Fig. 6, is arranged in its lower end position, the recess 64 of the Separating piston 12 and the flat end face 30 of the closing part 24 is connected in a fluid-conducting manner to the gap also delimited by the outer peripheral side 102, 104 of the central projection 92 of the separating piston 12 and the inner peripheral side of the fluid channel 32 in the region of its inner peripheral expansion 98, which in turn extends beyond the gap between the central projection 92 and the conically widening intermediate region 100 of the fluid channel 32 is fluid-conductingly connected to the fluid channel 32.

If the separating piston 12 arranged at a distance from the closure device 24 moves in the direction of the closure device 24, the central projection 92 first dips with its conically tapering peripheral side area 102 into the fluid channel 32 in the area of its inner peripheral expansion 98. During this movement, the gap between the outer peripheral side 102 of the central projection 92 and the inner peripheral side of the fluid channel 32 in the area of its inner peripheral expansion 98 narrows visibly due to the conically tapering peripheral side area 102 of the central projection 92, so that the discharge of the fluid quantity from the gap areas is progressively and increasingly throttled will. This results in a progressively increasing damping effect of the movement of the separating piston 12. The strongest throttling is achieved when the central projection 92 dips with its cylindrical peripheral side area 104 into the fluid channel 32 in the area of its inner peripheral widening 98.

In this way, as part of a constant throttling, large amounts of fluid can initially be discharged from the gap 66 between the separating piston 12 and the accumulator housing 24 without impairing the dynamics of the separating piston movement, in order to then carry out the end position damping 28 in a progressive manner while maintaining the dynamics to be able to Hydraulic accumulators or piston accumulators designed to that effect can easily be used for dynamically highly loaded hydraulic systems.

Claims

Patent claims Piston accumulator with an accumulator housing (10) and a separating piston (12) which can be moved longitudinally in the accumulator housing (10) and which separates two media chambers (14, 16) from one another, characterized in that between the separating piston (12) and accumulator housing (10) there is a End position damping (28) is provided, which has at least one gap (66, 72) which narrows with increasing movement of the separating piston (12) towards its end position and in this way builds up a flow resistance which inhibits the movement of the separating piston (12), and which is introduced as a recess (64, 78) in at least one of the adjacent end faces (30, 56) of the separating piston (12) and accumulator housing (10). Piston accumulator according to Claim 1, characterized in that the gap (66, 72) is an annular gap which comprises a media opening (32) which connects the interior of a media space (14) to the environment in a media-carrying manner, in particular to media-carrying components of a technical system, like a hydraulic system. Piston accumulator according to Claim 1 or 2, characterized in that the gap (66, 72) opens out in the direction of the media opening (32) and is delimited on the outer circumference by wall parts of the accumulator housing (10) and/or the separating piston (12). Piston accumulator according to one of the preceding claims, characterized in that when the separating piston (12) strikes the adjacent accumulator housing (10), the gap width is constant and that the gap (66, 72) of adjacent end wall parts (30, 56) running parallel to one another is limited by the floating piston (12) and accumulator housing (10). Piston accumulator according to one of the preceding claims, characterized in that the gap width decreases continuously in the direction of the media opening (32). Piston accumulator according to one of the preceding claims, characterized in that the gap (66, 72) is introduced as a depression (64, 78) in the end wall (30, 56) of the separating piston (12) and of the accumulator housing (10). Piston accumulator according to one of the preceding claims, characterized in that the separating piston (12) delimits the gap (66, 72) in at least one of its end positions with piston parts on the outer circumference and inner circumference against the accumulator housing (10). Piston accumulator according to one of the preceding claims, characterized in that the separating piston (12) has a pin-like extension (92) on its free end face (56) facing the media opening (32), which forms part of the end-position damping (28) when it becomes effective into the media opening (32). Piston accumulator according to one of the preceding claims, characterized in that the continuously decreasing gap size is at least partially formed by a cone in the separating piston (12). Piston accumulator according to one of the preceding claims, characterized in that the accumulator housing (10) is formed from at least one, preferably cylindrical, housing wall (25) and from a, preferably cylindrical, closing part (24) which has the media opening (32) and preferably is screwed into the housing wall (25).