Hydraulic Accumulator

Abstract

The invention relates to a hydraulic accumulator, in particular a piston accumulator, in the form of a separation element 10 arranged in an accumulator housing 14 and separating two fluid chambers 16, 18 from one another in a fluid-tight manner, in particular the separation element 10 separating in a fluid-tight manner a closed storage chamber 20 containing a working gas from a liquid chamber 22 containing a hydraulic fluid, such as a hydraulic oil, a fluid connection 24 being fluidly connected to one of the two fluid chambers 18, and a mounting part fixed to the accumulator housing 14 outside the accumulator housing 14, the mounting part having a magnetic field generating device 44 acting on the fluid connection 46 between the fluid connection 24 of the accumulator housing 14 and the fluid connection 25 of the mounting part 26, such that magnetizable particles can be washed away from the fluid passing through the fluid connection 46.

Description

[Technical field]

[0001] The present invention relates to a hydraulic accumulator, in particular in the form of a piston accumulator having a separation element arranged in an accumulator housing and fluid-tight separating two fluid chambers from one another, in particular the separation element fluid-tight separating a closed storage chamber containing a working gas from a liquid chamber containing a working fluid, such as hydraulic oil, and a fluid connection fluidly connected to one of the two fluid chambers. [Background technology]

[0002] Hydraulic accumulators, for example (hydropneumatic) piston accumulators, are used in hydraulic systems to hold a certain volume of pressurized liquid, for example hydraulic oil, and return this liquid to the hydraulic system when required. In commonly used hydropneumatic piston accumulators, in which a piston separates an oil-side fluid chamber from a storage chamber enclosed in an accumulator housing that holds a working gas, such as nitrogen gas, the position of the piston changes during the operation of the hydraulic accumulator, such that the hydraulic accumulator takes in hydraulic oil when the pressure increases and, in the process, the working gas in the other fluid chamber or storage chamber is simultaneously compressed. When the pressure decreases, the compressed gas expands again and, in the process, pushes the stored hydraulic oil back into the hydraulic circuit. The resulting change in the volume of the working chamber that occurs during operation leads in each case to a corresponding axial movement of the piston in the accumulator housing.

[0003] During the operation of a hydraulic device, such as a working cylinder, for example a corresponding hydraulic accumulator is connected to the hydraulic working circuit, which generally has a filter device with a filter element for cleaning contaminant particles from the working fluid, such as hydraulic oil, which can be replaced with a new element if necessary. Despite these filter devices, it cannot be excluded that contaminant particles reach the clean side of the fluid and cause damage to the accumulator and its components if they reach the hydraulic accumulator. Filter elements are also limited in terms of their flow capacity and therefore cannot always be used at very high volumetric flows and associated high fluid pressures. In particular, when using piston accumulators, contaminant particles can unintentionally get into the sealing system of the separating piston, which can lead to failure of the accumulator and the associated hydraulic device. Since the contaminant particles that arise are often caused by wear of the hydraulic device, they are usually metallic in nature and, especially in the case of mechanical failure, such particles can be of such a size that the sealing device on the separating piston is prone to leak or even destroyed with its elastomeric material.

[0004] DE 10 2016 007 798 A1 discloses a hydropneumatic piston accumulator with an accumulator housing with a cylinder tube defining a longitudinal axis, which cylinder tube is in each case sealed at both ends by a housing cover, in which a piston is guided in such a way that it is longitudinally displaced as a separating element in the housing, separating a fluid chamber for a compressible fluid, such as a working gas, from another fluid chamber for an incompressible fluid, such as a hydraulic oil, and with a displacement measuring device for contactlessly determining the position of the piston in the housing, which displacement measuring device extends along the longitudinal axis from one housing cover to the other through a passage formed in the piston and is sealed against the inner chamber of the housing. A position sensor is slidably guided in the tube itself so as to follow the movement of the piston by means of a magnetic force acting between it and the piston in the measuring tube. A permanent magnet is provided on the piston to generate a magnetic force which forces subsequent movement of the position sensor within the measuring tube. The permanent magnet, which moves continuously with the separating piston during operation of the accumulator, is received in the fluid chamber with the compressible working gas.

[0005] DE 41 16 482 A1 discloses a method and a device for measuring the pressure of the working gas in a pneumatic accumulator, which can be connected to a hydraulic working circuit, the working gas being separated from the working liquid by a separating element in the form of an elastomeric accumulator bladder. When the accumulator bladder is in a defined position, the gas pressure resulting from this position is measured by a pressure sensor arranged on the fluid side, and for this purpose the position of the disk valve of the accumulator is monitored by a monitoring device. For this purpose, the disk valve has a switching element with a permanent magnet in the fluid connection of the accumulator, the associated sensor consisting of a switch which can be actuated by a magnet or using the so-called Hall effect, as soon as depending on the working position of the disk valve, the switching element is guided past the associated sensor and triggers it.

[0006] A cube shaped magnet that moves continuously back and forth during operation of the accumulator is inadequate to effectively counteract contaminant particles that arise on the liquid side of the accumulator, as is a ring magnet on the gas side of the accumulator housing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] DE 102016007798 A1 [Patent Document 2] DE 4116482 A1 Summary of the Invention [Problem to be solved by the invention]

[0008] Based on this state of the art, the present invention is therefore based on the object of further improving the known hydraulic accumulator solutions in such a way that failures can be excluded even in the event of the occurrence of metallic contaminating particles. [Means for solving the problem]

[0009] This problem is solved by a hydraulic accumulator having the features of claim 1 of the present application.

[0010] According to the characterizing part of claim 1 of the present application, a fitting with a magnetic field generating device is fixed to it outside the accumulator housing, the magnetic field generating device acting on the fluid connection between the fluid connection of the accumulator housing and the fluid connection of the fitting in such a way that the magnetizable particles can be separated so as to be washed from the fluid passing through the fluid connection, thus providing the possibility of generating a strong stationary magnetic field fixed in position in such a way that magnetizable particles, in particular metallic particles, cannot reach the liquid side of the accumulator housing in the first place and therefore do not cause any damage, in particular to the separating element such as the separating piston. In particular, the magnetizable particles can be reliably collected outside the accumulator housing so that they cannot inadvertently reach the liquid side of the accumulator.

[0011] This ensures that contaminating particles cannot reach the sealing side of the separation piston with the sealing ring and guide band of the hydro-pneumatic piston accumulator, which otherwise could lead not only to sealing problems but also to the separation piston inside the accumulator housing being "caught" due to friction, so that the separation piston can no longer move and render the hydro-pneumatic accumulator totally unusable. Reliable cleaning of metallic magnetizable particulate components from the fluid flow is achieved by magnetic separation installed upstream of the hydro-pneumatic accumulator, especially when the filter device controls the fluid flow reaching its limits.

[0012] In a preferred embodiment of the hydraulic accumulator according to the invention, the mounting part is designed in a cuboid or rectangular parallelepiped shape and is provided with an engagement and is either screwed into the accumulator housing or is connected flush to the accumulator housing via a plate-shaped flange connection, in such a way that it can be mounted space-savingly below the hydraulic accumulator in its vertical operating position and is therefore part of the associated piping system by which the piston accumulator can be connected to a standard hydraulic circuit associated with associated pressure supply devices such as hydraulic pumps and hydraulic consumers such as working cylinders.

[0013] Preferably, the accumulator housing has a cylindrical housing wall sealed at at least one end by a housing cover, the housing cover being provided with a fitting on its outer or underside facing away from the separation piston.

[0014] In a further preferred embodiment of the hydraulic accumulator according to the invention, the fluid connection in the fitting extends coaxially in a straight line or at right angles thereto, and the magnetic field generator is arranged transversely to at least a portion of the fluid passage and engages with the fluid passage in the fitting. The transverse path of the magnetic field generator to the fluid flow moving in the fluid connection ensures that the fluid passes through the magnetic field generator over a relatively long distance, so that it can "fish out" problematic contaminant particles in a particularly efficient manner before entering the accumulator housing.

[0015] In a particularly preferred embodiment of the hydraulic accumulator according to the invention, the magnetic field generating device is formed from a permanent magnet, and the removal of magnetizable particles from the fluid flow is possible without the introduction of external energy. However, in special cases, it is also conceivable to use energizable magnets instead of permanent magnets in order to increase the efficiency, but this requires a corresponding energy supply to the accumulator housing of the hydraulic accumulator and / or its mounting parts.

[0016] Preferably, the permanent magnet comprises a magnetic rod, which is inserted into the fluid connection by means of a fastening screw at an axial and radial distance relative to the housing part of the fitting. Because of the use of a filter element in a hydraulic operating circuit, the occurrence of magnetizable contaminant particles is likely to be rather rare, and therefore, due to the expected large amount of dirt, it is not absolutely necessary to manually clean the magnetic field generator. However, in any case, it is always possible to remove the magnetic field generator from the fluid connection via the fastening screw for cleaning and / or replacement, and to reinsert it into the fluid passage of the fitting for a new operation after cleaning or after a maintenance operation. It is not necessary to disconnect the hydraulic accumulator from the rest of the hydraulic circuit in order to remove the permanent magnet for inspection purposes. In a further advantageous embodiment, the fastening screw can be designed as a so-called magnetic plug and thus form part of the effective permanent magnet. Preferably, the fitting is also made of a non-magnetizable material, such as stainless steel, in order to prevent metal particles from getting caught in the corresponding fixed openings of the fitting, for example when the fastening screw as part of the permanent magnet or magnetic plug is loosened. The particles can also be more completely removed from the magnetic field generating device.

[0017] To prevent leakage and possible leak points, a seal, usually in the form of at least one O-ring, is provided at the connection point between the fitting and the accumulator housing, however such a seal may be omitted if the fitting is an integral part of the corresponding housing cover of the accumulator housing.

[0018] For an energy-efficient use at full operating capacity, the hydraulic accumulator is preferably formed from a separation piston whose separation element can move longitudinally in the accumulator housing, which in one of its possible stop positions is flush with the housing cover with the fluid connection and is designed to cover it without a step when the fluid chamber is completely emptied. During the operation of the separation piston, in particular when the hydraulic fluid is returned from the fluid chamber in the direction of the hydraulic operating circuit, high fluid flow velocities arise, whereby in some cases this high fluid flow velocity can clean the magnetic field generating device with the fluid flow, whose collected and removed contaminant particles can be cleaned from the fluid flow by the filter element during normal filtering operation. In this way, when the fluid is supplied to the accumulator, the contaminants can be washed in countercurrent by the magnetic field generating device or during the discharge operation of the hydraulic accumulator, which can remove said contaminant particles in the return flow, i.e. during the accumulator discharge. The separating piston can be formed as a hollow piston in order to increase the volume of the gas chamber in the direction of the gas side, but such a hollow piston design is additionally or alternatively also possible in the opposite arrangement on the fluid side, so that in high pressure conditions the piston does not strike the liquid side housing cover with its entire surface. It is also possible to design the separating piston as a solid cylindrical plate to ensure that it cannot strike the gas side housing cover when high operating pressures occur.

[0019] In the following, the hydraulic accumulator according to the invention is explained in more detail by means of four exemplary embodiments. The figures below are shown in principle and are not to scale. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 shows the essential structure of a hydraulic accumulator as a whole in the form of a longitudinal section. [Diagram 2] FIG. 2 is an enlarged view of the portion marked X in FIG. [Diagram 3]FIG. 3 is a bottom view of the hydraulic accumulator according to FIG. [Figure 4] FIG. 4 shows a representation of a second embodiment corresponding to FIG. [Diagram 5] FIG. 5 shows a representation of a second embodiment corresponding to FIG. [Figure 6] FIG. 6 shows a third embodiment corresponding to FIG. [Figure 7] FIG. 7 shows a third embodiment corresponding to FIG. [Figure 8] FIG. 8 shows a third embodiment corresponding to FIG. [Figure 9] FIG. 9 shows a representation of the fourth embodiment corresponding to FIG. [Figure 10] FIG. 10 shows a representation of the fourth embodiment corresponding to FIG. [Figure 11] FIG. 11 shows a representation of the fourth embodiment corresponding to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The hydraulic accumulator according to the invention, shown in FIG. 1 in the form of a so-called piston accumulator, comprises a separating piston 12 as separating element 10, which separates two fluid chambers 16, 18 arranged in an accumulator housing 14 from one another. The upper fluid chamber 16, as viewed in the direction of FIG. 1, forms a closed storage chamber 20 for receiving a working gas, for example nitrogen gas, whereas the lower fluid chamber 18 forms a liquid chamber 22 for receiving a working fluid, for example hydraulic oil. Each fluid chamber 18 or liquid chamber 22 is provided with a channel-like fluid connection 24, via which the accumulator can be connected to a fitting 26. The associated fitting 26, and thus also the hydraulic accumulator, can be connected, for example via piping, to a hydraulic working circuit of conventional type, which is not shown in more detail.

[0022] The accumulator housing 14 is designed as a so-called cylindrical cylinder or cylindrical tube, the two free ends of which are in each case tightly sealed by threaded housing covers 28, 30, between which the separation piston 12 is guided so as to be freely movable along the longitudinal axis 32 of the housing. The upper housing cover 28 is provided with a continuous fluid channel 34, which is sealed by a threaded plug 36, as shown in FIG. 1. Via the associated connection arrangements 34, 36, the accumulator can evacuate the working gas in the fluid chamber 16 if necessary, for example for maintenance work purposes, but can also fill the associated fluid chamber 16 if the working gas is not sufficient. The separation piston 12 itself is designed as a so-called hollow piston, with the aim of increasing the effective gas volume on the fluid chamber 16 side. However, the separation piston 12 can also be provided with a cavity on the liquid side of the accumulator or designed as a solid cylinder (cylindrical body). The outer periphery of the separation piston 12 is guided along the inside of the cylindrical accumulator housing 14 via at least one sealing ring 38 and at least one guide band 40. In actual implementation, a number of said sealing rings and guide bands can be combined with each other and fitted onto the outer periphery of the separation piston 12.

[0023] As can also be seen in the diagram of FIG. 3, operating aids 42 can be arranged on the outside of the respective housing cover 28, 30, here in the form of four blind holes arranged diametrically opposite the longitudinal axis 32, which allow the engagement of a corresponding operating tool in order to make it easier to screw and unscrew the respective housing cover 28, 30 onto the associated threaded portion on the inner circumference of the accumulator housing 14.

[0024] Previous designs of such hydraulic accumulators, here in the form of piston accumulators, are common and therefore will not be described in any further detail, but only to the extent necessary for understanding the present invention.

[0025] As can be seen in particular from the enlarged view according to Fig. 2, a magnetic field generator 44 is fitted into the fitting 26, which acts on a tubular or channel-like fluid connection 46 in the fitting 26, which passes between the fluid connection 24 of the accumulator housing 14 and an associated fluid connection 48 of the fitting 26. Via the fluid connection 46, fluid from the hydraulic supply circuit flows into the fluid chamber 18 during the accumulator charging and accumulator discharging processes, and during the accumulator unloading operation of the hydraulic accumulator, this fluid is returned again from the second fluid chamber 18 into the hydraulic working circuit, under the pre-pressure of the working gas in the first fluid chamber 16. In particular, the fluid flowing into the accumulator may comprise magnetizable contaminant particles, in particular metallic contaminant particles, which are prevented by the magnetic field generator 44 in the fluid connection 46 of the fitting 26 from entering the accumulator on its liquid side, which is formed by the second fluid chamber 18.

[0026] The fitting 26 is formed from a solid block in the shape of a rectangular parallelepiped having an engagement portion 48 arranged on its free end face, which can be screwed into the lower housing cover 30 by forming a threaded portion 50 in order to establish a fluid passage to the fluid connection 46 in the fitting 26. Between the fitting 26 arranged on the bottom side and the housing wall of the lower housing cover 30 adjacent and facing the fitting 26, a seal 52, for example in the form of an O-ring, is provided, which surrounds and engages the pin-like engagement portion 48, through the center of which the fluid connection 46 passes continuously.

[0027] In its coaxial arrangement with respect to the longitudinal axis 32 of the housing, the fluid connection 46 is exposed at its lower end to the atmosphere via a portion 54 having an internal thread to allow for the screwing of standard piping leading to a hydraulic supply circuit (not shown). In this way, the hydraulic accumulator with the accumulator housing 14 and the fittings 26 can be fluidly connected to other hydraulic components.

[0028] In the mounting part 26, in the direction of view from the right in Figs. 1-3, the magnetic field generator 44 is fitted from the outside into the fluid connection 46. For this purpose, the fluid connection is designed as a so-called T-shaped connecting piece and forms a centrally arranged fluid chamber 56 in the form of a blind hole, with the maximum free channel cross-section of the entire fluid connection 46 extending in its longitudinal orientation, transverse to the longitudinal axis 32 of the housing and therefore transverse to the other connecting parts of the fluid connection 46. In this process, the free diameter of the part 54 is selected to be larger than the inner diameter area of ​​the hollow-tubular engagement part 48. The magnetic field generator 44 is formed from a permanent magnet with a magnetic rod 58, which is screwed into the fluid chamber 56 transverse to the rest of the fluid connection 46 by means of a fixing screw 60 having an axial and radial distance to the housing part of the mounting part 26. To increase the magnetic force, the fixing screw 60 can also be formed from a magnetic material. However, the housing parts of the fitting 26 itself are preferably made, wherever possible, of a non-magnetizable material, for example a stainless steel material. If magnetizable particles collect on the rod 58 and / or the screw 60, the magnetic rod 58 can be removed from the fitting 26 via the fixing screw 60 and washed, as part of normal maintenance work, without the need to dismantle the accumulator itself. After screwing in the magnetic field generator 44 in the form of the aforementioned permanent magnet, the particle collection function is again available during operation of the hydraulic accumulator. If changes in the magnetic field lines are a consideration in the design, the fitting 26 can be made from a magnetizable material.

[0029] 1 and 2, the mounting part 26 can also be used retroactively as a so-called installation kit for hydraulic accumulators that have already been supplied. In principle, it is also possible for the mounting part 26 to be formed integrally with the housing cover 30, so that the threaded part 50 and the engagement part 48 can be omitted, as well as the seal 52 in the region of the mounting part 26 and the lower end wall or the outer wall of the housing cover 30.

[0030] The embodiments presented below are merely described insofar as they differ significantly from the previous embodiments, the same components are given the same reference numerals and the previous description also applies to the modified embodiments.

[0031] In the solution according to Fig. 4 and Fig. 5, the magnetic field generator is fitted into a T-shaped fluid connection area under the mounting part 26 as seen in the drawing direction, and the free fluid flow is guided to the right across the mounting part 26. The not shown piping for the hydraulic actuation circuit can then be connected to the corresponding inlet and / or outlet points 62. The fluid chamber 56 with the magnetic field generator 44 is then received in the block-shaped mounting part 26 coaxially with the longitudinal axis 32 of the housing of the piston accumulator. The magnetic rod 58 or magnetic plug 60 is inserted, in particular screwed, from below into the mounting part 26 coaxially with the longitudinal axis 32 of the housing at a corresponding axial and radial distance to the fluid chamber 56. In this embodiment, the free end of the magnetic rod 58 emerges in each case in the associated fluid connection 46 below the engagement part 48. The fixing screw 60 with the magnetic rod 58 is screwed into the fitting 26 from below, so that a so-called fluid barrier is created which promotes a right-angle deflection of the fluid flow towards the inlet and / or outlet points 62 during the accumulator discharge operation.

[0032] In the embodiment according to Figures 6 to 8, the cuboid-shaped mounting part 26 is detachably connected to the underside of the lower housing cover 30 by a flat flange plate 64, shown only in outline in Figure 8, via four fastening screws 66. As in the embodiment according to Figures 4 and 5, here too the magnetic field generator 44 is fitted into the mounting part 26 from below at a right-angled connection point 62. Here, the free end of the magnetic rod 58 just reaches the inlet opening of the channel-like fluid connection 24 in the lower housing cover 30. An O-ring seal is again used to provide the seal 52 between the mounting part 26 and the lower housing cover 30. As a direct comparison of the embodiment according to Figures 1 to 5 with the embodiment according to Figures 6 to 8 shows, the flange plate fastening for the mounting part 26 on the accumulator housing 14 allows the mounting depth to be reduced, which saves space.

[0033] In comparison with the previous embodiment, according to the design according to Figures 9 to 12, in Figures 9 and 10, the magnetic field generator 44 is arranged to the left of the mounting part 26. The mounting part 26 is fixed to the bottom of the accumulator housing by means of respective screws 66 as a so-called flange plate and is thus securely connected to the lower housing cover 30. In a particularly pressure-resistant design, the bottom of the mounting part 26 is closed and the fluid connection 46 is also designed as a T-piece.

[0034] From the above embodiments it has become clear that in the form of a modular system, the mounting parts 26 are more or less identically designed and, by suitable selection of the fluid connections 46 and of the installation space for the magnetic field generator 44 in the mounting parts 26, the magnetic field generator 44 can always be removably fitted to the accumulator housing 14 in an easily accessible place. This is not equivalent to the prior art.

Claims

1. A hydraulic accumulator, in particular in the form of a piston accumulator, provided with a separating element (10) arranged in an accumulator housing (14) and separating two fluid chambers (16, 18) from each other in a fluid-tight manner, In particular, the separation element (10) fluid-tightly separates a closed storage chamber (20) containing a working gas from a liquid chamber (22) containing a working fluid, such as hydraulic oil; A hydraulic accumulator, wherein the fluid connection (24) is fluidly connected to one of the two fluid chambers (18), 1. A hydraulic accumulator comprising: a mounting part (26) fixed to the accumulator housing (14) outside the accumulator housing (14), the mounting part (26) having a magnetic field generating device (44) acting on a fluid connection (46) between the fluid connection (24) of the accumulator housing (14) and the fluid connection (25) of the mounting part (26) such that magnetizable particles can be washed away from the fluid passing through the fluid connection (46).

2. 2. The hydraulic accumulator according to claim 1, wherein the mounting part (26) is designed in the shape of a cube or a rectangular parallelepiped, has an engagement part (48), and is screwed into the accumulator housing (14) or is connected flush to the accumulator housing (14) via a flange plate (64).

3. 2. A hydraulic accumulator according to claim 1, characterized in that the accumulator housing (14) has a cylindrical housing wall sealed at least at one end by a housing cover (30), the housing cover (30) having the mounting part (26) on its outer side opposite the separation piston (12).

4. the fluid connection (46) in the fitting (26) extends coaxially and linearly with the fluid connection (24) in the accumulator housing (14) or perpendicularly to the fluid connection (24); 2. The hydraulic accumulator according to claim 1, wherein the magnetic field generating device (42) is arranged transversely to at least a portion of the fluid connection (46) and engages the fluid connection in the mounting part (26).

5. 2. A hydraulic accumulator according to claim 1, characterized in that the magnetic field generating device (44) is formed from a permanent magnet.

6. A hydraulic accumulator as described in claim 1, characterized in that the permanent magnet has a magnetic rod (58) inserted into the fluid connection part (46) by a fixing screw (60) at an axial and radial distance from the housing part of the mounting part (26).

7. Hydraulic accumulator according to any one of claims 1 to 6, characterized in that the fixing screw (60) is designed as a magnetic plug and is part of a permanent magnet.

8. 2. A hydraulic accumulator according to claim 1, characterized in that the mounting part (26) is made of a non-magnetic material such as stainless steel.

9. 2. A hydraulic accumulator according to claim 1, characterized in that a seal (52) is present at the connection point between said fitting (26) and said accumulator housing (14).

10. 10. A mounting assembly provided as an installation kit for the piston accumulator of claim 1, comprising: A mounting part, characterized in that the magnetic field generating device (44) is inserted into a fluid connection (46) in a mounting block, which has two fluid connection points (24, 25) leading to the outside.

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