Piston type energy accumulator

Abstract

The utility model relates to a piston type energy accumulator which is provided with an energy accumulator shell (10) and a buffering device (18), and a separating piston (12) is guided in the energy accumulator shell in a longitudinal moving mode. The separating piston separates two fluid chambers (14, 16), in particular one fluid chamber (14) with a working gas, from the other fluid chamber (16) with an operating fluid, such as hydraulic oil, from one another, characterized in that a half-flow device (20) is arranged next to the damping device (18), the energy accumulator housing (10) has a wake device (24), which interacts with the damping device (18) in order to dampen a fluid flow exiting the energy accumulator housing (10), forming a throttle valve along a fluid path (22), and which releases the other fluid path (24), bypassing the fluid path (22) having the throttle valve, the fluid is introduced into the accumulator housing (10) in order to follow the fluid into the accumulator housing (10).

Description

Technical Field

[0001] The utility model relates to a piston accumulator, which has an accumulator housing, in which a separation piston is guided in a longitudinally movable manner, the separation piston separates two fluid chambers, in particular a fluid chamber with working gas and another fluid chamber with operating liquid such as hydraulic oil, from each other, and the piston accumulator has a buffer device. Background Art

[0002] EP 0 286 777 A2 discloses a piston-cylinder unit of the type described, which has a piston end position damper with a damping piston protruding on the piston end face, which can be moved into a damping chamber arranged on the deflected cylinder end while forming a damping gap tapering conically in the direction of the fluid connection, and for inducing the backstroke movement of the piston, a flow path is provided, which leads from the fluid connection for the pressure oil to a pressure chamber in the accumulator housing adjacent to the main piston face of the piston while bypassing the damping gap and contains a non-return valve. This flow path, which can be controlled by the non-return valve, extends within the piston between an inlet opening at the front end of the damping piston, which is designed as a hollow sleeve, and a penetration in the form of a transverse channel leading outward from the interior of the sleeve. In this regard, the non-return valve used has a solid valve plate that can be controlled by an accumulator in the form of a compression spring, which controls a large opening cross section in the damping piston, which leads to a leak in the closed position and is accompanied by turbulence in the flow process when the piston is opened. Furthermore, rapid opening and closing operations are excluded due to the inertia of the valve plate. Utility Model Content

[0003] Therefore, starting from such prior art, the purpose of the present invention is to further improve the known solution as follows, that is, to provide a piston accumulator, which, in addition to having an improved response behavior when fluid flows into or out of the hydraulic accumulator, also has an improved end position buffer for separating the piston.

[0004] To this end, the invention provides a piston accumulator having an accumulator housing and a damping device, in which a separating piston is guided in a longitudinally displaceable manner, the separating piston separating two fluid chambers from one another, and a wake device additionally provided next to the damping device, the wake device cooperating with the damping device while forming a throttle valve along one fluid path for damping a fluid flow out of the accumulator housing, and the wake device, while bypassing the one fluid path with the throttle valve, releases the other fluid path for the fluid wake to enter the accumulator housing, thereby achieving reliable damping of the separating piston when the piston accumulator is discharged until it reaches a possible stop position on a component of the accumulator housing, such as a housing cover, and in the opposite direction of movement of the separating piston, when the accumulator is charged and operating fluid flows into the other fluid chamber, the wake device opens while bypassing the one fluid path with the throttle valve, thereby directly charging the entire piston cross section with fluid at a pre-settable pressure and causing the separating piston to move into the other fluid chamber against the preload pressure of the working gas. In this way, high dynamics are achieved for the return movement of the separating piston within the scope of the accumulator charging process.

[0005] If the damping device completely disengages from the wake device when the separating piston moves further back in the direction of the one fluid chamber containing the working gas, a wake flow of fluid into the other fluid chamber is additionally achieved via the fluid cross section released in this way, which helps to further accelerate the charging process for the energy storage device.

[0006] The solution according to the invention achieves not only improved damping behavior during unloading of the piston accumulator, but also improved, unimpeded return flow during accumulator charging operations, during which the separating piston can be displaced in the one fluid chamber against the preload pressure of the working gas.

[0007] In a preferred embodiment of the piston accumulator according to the invention, it is provided that the damping device has a damping piston on the separating piston and the wake device has a wake piston which is movably guided in a part of the accumulator housing. Due to the low inertia of the damping piston and the wake piston, the fluid flows occurring in each case when charging and unloading the piston accumulator can be reliably controlled in a rapid temporal sequence, so that piston accumulators which have to provide a large number of load changes even at high fluid pressures are improved within the scope of the charging and unloading processes compared to solutions in the prior art.

[0008] In another preferred embodiment of the piston accumulator according to the invention, it is provided that for the damping process, the damping piston is inserted into the one fluid path in the recess of the wake piston while forming a throttle gap as a throttle valve. Here, the throttle gap is a cylindrical annular chamber with a variable volume, which is formed by adjacent wall parts of the damping piston and the wake piston. In this way, a constant throttle gap width is achieved in the wake piston over the entire engagement length of the damping piston, which achieves significantly improved end position damping. Since, as shown in the prior art, a continuously changing gap geometry with a conical section does not need to be taken into account, the engagement length for the damping piston can be selected to be particularly long within predeterminable limits (determined by the geometry to be maintained for the piston accumulator), so that a significantly improved piston end position damping is achieved in combination with a constant gap size over the entire engagement length.

[0009] In another preferred embodiment of the piston accumulator according to the invention, it is provided that the wake piston is accommodated in a housing cover as part of the accumulator housing and is embedded in a fluid connection which establishes a fluid connection with the other fluid chamber with the operating fluid via a corresponding fluid path. In this way, both the damping device and the wake device are accommodated in the housing cover with their respective fluid paths to be actuated in a space-saving manner, and due to the selected design, the relevant arrangement can also be retrofitted into an already existing conventional piston accumulator and thus improve the damping performance and the wake performance.

[0010] In another preferred embodiment of the piston accumulator according to the invention, it is provided that the wake piston is supported in the housing cover in an axially displaceable manner by means of a locking ring, so that in the lowered position the further fluid path is blocked and in the raised position this fluid path is released. Due to the locking ring fixation, in the end position of the separating piston, both the damping device and the wake device can be fixed in a particularly assembly-friendly manner on the free end side of the separating piston and are accommodated together in a fluid connection of the adjacent housing cover, which fluid connection establishes a fluid connection between the further fluid chamber between the separating piston and the housing cover and the remaining hydraulic circuit with its components which can be connected to the fluid connection by means of a pipe.

[0011] In another preferred embodiment of the piston accumulator according to the invention, it is provided that the wake piston is embedded in the widened cross section in the housing cover in such a way that a cylindrical flow space is established between the cylindrical outer circumference of the wake piston and the adjacent, opposite inner circumference of the housing cover as a component of the further fluid path. It is also preferably provided that the wake piston is provided with a spherically extending contact surface on its end side facing away from the separating piston, which contact surface can be placed against a conical bearing surface in the housing cover when forming a valve seat. By means of the partially spherical valve seat, an articulated support of the wake piston on the separating piston with play is achieved even when a locking ring guide is used, in order to compensate for tolerances between the separating piston (when its sealing and guide strips are introduced) and an adjacently arranged wall part or shell part of the accumulator housing (especially when an associated housing cover is introduced). For an improved valve seat geometry, it is also possible that the free end side of the wake piston facing away from the separating piston can be designed as a hexagon or provided with a "countersunk".

[0012] In order to reliably guide the damping piston in the wake piston, it is preferably provided that, at least in the completely unloaded state of the piston accumulator, the damping piston completely penetrates the wake piston and engages in the wake piston, preferably with an at least partially conically extending closure portion as an introduction aid, until reaching the edge-side projection.

[0013] The utility model also relates to a method for operating the piston accumulator described above, characterized by the following steps:

[0014] - when the piston accumulator is unloaded, the volume flow is throttled by forming a hollow cylindrical throttling gap between the damping device and the wake device,

[0015] - when the piston accumulator is charged, the piston gap is bypassed by opening the wake device and, as a result,

[0016] The entire free cross section of the separating piston is acted upon with fluid pressure in order to move the separating piston directly in the direction of a fluid chamber containing the working gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The piston accumulator according to the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 The lower part of an otherwise conventional piston accumulator, as shown by way of example in the aforementioned EP 0 286 777 A2, is shown in longitudinal section; and

[0019] Figure 2 Shown corresponding to Figure 1 , but in the open piston position and without the piston securing device. DETAILED DESCRIPTION

[0020] Figure 1 The lower part of a piston accumulator is shown, which has a hollow cylindrical wall part 8 of an accumulator housing, which is generally designated by 10, in which a separating piston 12 is guided so as to be displaceable in the longitudinal direction, and which separates two fluid chambers 14, 16, in particular a fluid chamber 14 with a working gas such as nitrogen and a further fluid chamber 16 with an operating fluid such as hydraulic oil from one another. In addition, the separating piston 12 has a damping device 18 integrally connected thereto at its free end. A wake device 20 is also provided, which cooperates with the damping device 18 while forming a throttle valve along a fluid path 22, in order to damp the fluid flow out of the accumulator housing 10, and the wake device is arranged according to Figure 2 The simplified illustration of , while bypassing the one fluid path 22 with the throttle valve, releases the other fluid path 24 for the accompanying flow of fluid into the accumulator housing 10 .

[0021] like Figure 1 and Figure 2 As further shown, the damping device 18 has a damping piston 26, which is preferably connected integrally to the separating piston 12 and arranged centrally on the lower free end side 28 of the separating piston 12. The wake device 20 also has a wake piston 30, which is movably guided in a component of the accumulator housing 10, in this case in the form of a housing cover 32. The housing cover 32 mentioned as part of the accumulator housing 10 is screwed into its hollow cylindrical wall part 8 at the bottom side and is sealed relative to the other parts of the accumulator housing 10 via an annular seal, not shown in detail. The separating piston 12 itself has two annular grooves 34, 36 on the outer circumference for accommodating sealing rings and guide strips, not shown in detail.

[0022] For the damping process, the damping piston 26 moves from the upper position into the cylindrical recess 38 of the follower piston 30, into the first fluid path 22 formed in this respect while forming a throttle gap 40 as a throttle. Figure 1 The displacement movement of the separating piston 12 from top to bottom to the liquid side of the accumulator ends when the separating piston 12 with its end side 28 at least partially comes into contact with the upper side 42 of the housing cover 32. Here, the stop body 44 distributed on the end side 28 of the separating piston 12 serves as a stop limit for the end side 28. Figure 1 and Figure 2, an annular gap 46 is formed between the flat end face 12 of the separating piston 12 and the upper side 42 of the housing cover 32 (except for the stop body 44 which acts as a stop), which serves as an additional damping gap and, in terms of the damping function, displaces the fluid from the further second fluid chamber 16 in the direction of the throttling gap 40 (formed by the wall parts of the damping piston 26 and the wake piston 30 which are adjacent to each other). As a result, the operating fluid displaced from the fluid chamber 16 in the direction of the fluid connection 48 reaches the unloading position of the accumulator, via which the accumulator can be connected to the hydraulic working circuit by means of conventional piping (not shown). In this regard, for the unloading process, the accumulator is held pressureless on the side of the fluid connection 48, and the separating piston 12 is moved into its end position shown in the figure under the preload pressure of the working gas in the fluid chamber.

[0023] The wake piston 30 is accommodated in a receiving chamber 50 in the lower housing cover 32 as part of the accumulator housing 10 and, as already described, is inserted into the fluid connector 48, which establishes a fluid connection with the other fluid chamber 16 containing operating fluid via corresponding fluid paths 22, 24 and via a third fluid path 52, which is obtained when the release piston 12 is completely disengaged from the hollow cylindrical recess 38 in the wake piston 30 by the reverse stroke movement of the release piston 12 under the fluid pressure of the fluid connector 48 in the accumulator charging position together with the upward movement of the release piston 12.

[0024] Before the damping piston 26 is disengaged from the wake piston 30, the damping piston 26 is disengaged from the wake piston 30 according to Figure 2 The illustration is first lifted axially upward by the fluid pressure in the fluid connection 48, and the outer peripheral side of the damping piston 26 forms a cylindrical sub-guide for this purpose. Figure 2 , the wake piston 30 is lifted by the fluid pressure in the fluid connection 48 and the second fluid path 24 is released in such a way that the added fluid reaches the free end side 28 of the separating piston 12 and the wake piston is lifted together with the damping piston 26 in the fluid chamber 14 under the fluid pressure against the preload pressure of the working gas. In this way, a fluid connection 54 (according to the method according to the invention) is established at least via the second fluid path 24 with the further fluid chamber 16 having the operating fluid. Figure 2 ).

[0025] The separating piston 2 and the two pistons 26, 30 as well as the fluid connection 48 in the lower housing cover 32 are arranged concentrically relative to each other and coaxially with the longitudinal axis 56 of the accumulator housing 10. In order to allow the wake piston 30 to be moved from its Figure 1 The closed position is moved to the Figure 2In the open position and move in the opposite direction, the wake piston is locked by means of an elastic locking ring 58 (only in Figure 1 ) is supported in the housing cover 32 in an axially movable manner. For this purpose, the locking ring 58 is embedded in the corresponding inner groove in the housing cover 32 on the outer circumference and is only provided on the inner circumference. Figure 1 The abutment shoulder 60 shown in FIG. 1 passes through the abutment shoulder 60, which is arranged according to Figure 2 In the raised position of the wake piston 30, the inner circumference of the locking ring 58 is brought into contact and can otherwise protrude downward from the locking ring 58 by a predefined distance (according to the Figure 1 In this way, at least the locking ring 58 can be used to cut off the other fluid path 24 ( Figure 1 ) and releases this fluid path 24 in the opposite raised position ( Figure 2 ). For the relevant function, the wake piston 30 is embedded in the widened cross section 62 in the housing cover 32, at least when forming the fluid connection 54, so that a cylindrical flow space for establishing the fluid connection 54 is realized between the cylindrical outer periphery of the wake piston 30 and the adjacent opposite inner periphery of the housing cover 32.

[0026] The follower piston 30 has, on its end side facing away from the separating piston 12, a spherically extending, in particular convex, contact surface 64 which can form a valve seat 66 ( Figure 1 ) is placed in contact with a corresponding conically extending bearing surface 68 in the housing cover 32. As a result, due to the spherical design, a self-adjustment of the wake piston 30 in the direction of the valve seat 66 on the housing cover 32 is achieved. In addition, centering of the wake piston 12 is also ensured if this separating piston enters into a corresponding hollow cylindrical recess 38 in the wake piston 30 with the aid of the cylindrical damping piston 26 as the throttle gap 40 increases.

[0027] In accordance with Figure 1 In the fully unloaded state shown in the figure, the damping piston 26 has then completely passed through the wake piston 30, and the damping piston 26 at least partially protrudes from the wake piston 30 on the edge side with a conically extending closing portion 70. When the separating piston 12 performs the corresponding downward movement on the liquid side of the hydraulic or piston accumulator within the scope of the unloading process, the end bevel formed thereby on the damping piston 26 allows unimpeded insertion into the wake piston 30.

[0028] If within the scope of the description orientations such as “upper” and “lower” are mentioned, this relates to the usual mode of operation of the piston accumulator in a vertical orientation.

[0029] exist Figure 1 and Figure 2The piston accumulator shown in at least one embodiment is operated in such a way that at least the following method steps are implemented:

[0030] - when unloading the piston accumulator, the volume flow is throttled by forming a hollow cylindrical throttling gap 40 between the damping piston 26 and the follower piston 30, and the fluid is pressed out of the fluid chamber 16 via the throttling gap 40 in the direction of the fluid connection 48 which remains unpressurized due to the associated upward movement of the separating piston 12. In this case, further throttling occurs via the annular gap 46 between the free end side of the separating piston 12 and the adjacent opposite upper side 42 of the housing cover 32 as a damping gap;

[0031] - When charging the piston accumulator, the wake piston 30 is moved from the Figure 1 The closed position is Figure 2 In the open position, the valve seat 66 is lifted from the valve seat 66 and the other fluid connection 24 is opened to bypass the relevant throttling or buffer gap 40, 46. Due to the pressure difference formed, the fluid under pressure reaches the piston fluid chamber 72 between the separating piston 12 and the housing cover 32 via the fluid connection 48, and then the separating piston 12 is lifted upward when viewed in the direction of the drawing and the liquid volume on the liquid side of the accumulator with the fluid chamber 16 increases significantly during further displacement against the preload pressure of the working gas in the fluid chamber 14. If the central recess 38 is released when the separating piston 12 moves upward by moving the buffer piston 26 away from the follow-flow piston 30, the other third fluid path 52 is released so that the fluid at a preset pressure can flow directly into the piston fluid chamber 72 via the fluid connection 48. The next step is determined by this.

[0032] The fluid pressure acts on the entire free piston cross section in order to move the separating piston 12 directly in the direction of the further fluid chamber 14 with the working gas. In this way, the accumulator charging process takes place in the manner of a poison arrow, and after the relevant operating cycle has been completed, the piston accumulator is then used again for the described unloading process.

[0033] According to Figure 1, a damping valve designated as a whole by 76 is provided in the region of the internal thread 74 of the fluid connection 48, which damping valve with a valve plate 78 that can be displaced in the longitudinal direction extends into a throttle bore 80 that is coaxial with the longitudinal axis 56 of the piston accumulator. The relevant valve plate 78 is accommodated in a valve housing 82 that is preferably designed as a tripod and is screwed flush into the associated fluid connection 48 along the internal thread 74. Since a fluid inlet 84 is provided between the legs of the valve housing 78, in the position shown, in order to load the accumulator via a bottom-side branch 86 in the valve seat 78, the fluid flows out of the hydraulic working circuit via the fluid connection 48 in the direction of the fluid chamber 16 when the follower device 20 is open, at a pre-settable pressure. In the opposite direction, i.e. when the accumulator is unloaded, the valve plate 78 is released from its position. Figure 1 76 into a lower closed position in which the valve plate 78 is supported on the inner side of the valve housing 82 and the fluid passage is only provided via the throttle opening 80 in the valve plate 78, so that in addition to the already described damping measures 40 and / or 46 by the damping valve 76, a throttling of the fluid flow is also achieved. Detailed details about the function and design of the damping valve can also be found, for example, in DE 103 37 744 B3.

[0034] As described, the relevant piston accumulators usually have a high preload pressure, which, in particular when rapidly unloaded below the gas preload pressure, exerts a large force on the separating piston 12 and its sealing system. Figure 1 and Figure 2 In the piston end position shown in FIG. 1 , an oscillating load acts on the separating piston 12 and the associated piston seal. This in turn results in the seal being constantly pressed against the groove side wall facing the hydraulic oil in the annular groove 34 in the separating piston 12 in an impact-like manner due to the existing gas pressure. The dynamics of the sealing system and the resulting seating effect of the seal in the annular groove 34 lead to increased gas losses in the piston accumulator. In addition, the hard metal impacts between the separating piston 12 and the housing cover 32 are acoustically disturbing and, in extreme cases, can also cause mechanical damage in this area.

[0035] The hydraulic end position damping according to the invention is used, as described, to move the separating piston 12 at a reduced speed to its position in the Figure 1 However, this also reduces the oscillating loads on the sealing system, which can effectively prevent gas losses and overall wear of the accumulator. Therefore, there is no corresponding solution in the prior art.

Claims

1. A piston accumulator comprising an accumulator housing (10) and a damping device (18), wherein a separating piston (12) is guided in the accumulator housing so as to be displaceable in the longitudinal direction and separates two fluid chambers from each other, and a wake device (20) is provided next to the damping device (18), characterized in that: The accompanying flow device (20) cooperates with the damping device (18) to form a throttle valve along a fluid path (22) for damping a fluid flow out of the accumulator housing (10), and the accompanying flow device (20) releases another fluid path (24) while bypassing the one fluid path (22) having the throttle valve for allowing a fluid accompanying flow to enter the accumulator housing (10).

2. The piston accumulator according to claim 1, characterized in that The two fluid chambers are a fluid chamber (14) containing a working gas and another fluid chamber (16) containing an operating liquid.

3. The piston accumulator according to claim 1, characterized in that The damping device (18) has a damping piston (26) on the separating piston (12), and the wake device (20) has a wake piston (30) which is movably guided in a part (32) of the accumulator housing (10).

4. The piston accumulator according to claim 2, characterized in that The damping device (18) has a damping piston (26) on the separating piston (12), and the wake device (20) has a wake piston (30) which is movably guided in a part (32) of the accumulator housing (10).

5. The piston accumulator according to claim 3, characterized in that For a damping process, the damping piston (26) is inserted into the one fluid path (22) in a recess (38) in the wake piston (30), forming a throttle gap (40) as a throttle valve.

6. The piston accumulator according to claim 4, characterized in that For a damping process, the damping piston (26) is inserted into the one fluid path (22) in a recess (38) in the wake piston (30), forming a throttle gap (40) as a throttle valve.

7. The piston accumulator according to claim 5 or 6, characterized in that The throttling gap (40) is a cylindrical annular chamber with a variable volume, which is formed by adjacent wall parts of the damping piston (26) and the wake piston (30).

8. The piston accumulator according to claim 4 or 6, characterized in that The wake piston (30) is accommodated in a housing cover (32) as part of the accumulator housing (10) and is embedded in a fluid connection (48) which establishes a fluid connection (54) with the further fluid chamber (16) containing operating fluid via a corresponding fluid path.

9. The piston accumulator according to claim 8, characterized in that The wake piston (30) is supported in the housing cover (32) in an axially displaceable manner by means of a locking ring (58), so that in a lowered position the further fluid path (24) is blocked and in a raised position the further fluid path (24) is released.

10. The piston accumulator according to claim 8, characterized in that The wake piston (30) engages in a widened cross section (62) in the housing cover (32), so that a cylindrical flow space is created between the cylindrical outer circumference of the wake piston (30) and the adjacent, opposite inner circumference of the housing cover (32).

11. The piston accumulator according to claim 8, characterized in that The wake piston (30) is provided with a spherically extending contact surface (64) on its end side facing away from the separating piston (12), which contact surface can be brought into contact with a conical bearing surface (68) in the housing cover (32) while forming a valve seat (66).

12. The piston accumulator according to any one of claims 3 to 6, characterized in that In its completely unloaded state, the damping piston (26) completely penetrates the wake piston (30).

13. The piston accumulator according to claim 12, characterized in that In its completely unloaded state, the damping piston (26) projects beyond the wake piston (30) at the edge with an at least partially conically extending closing section (70).

14. The piston accumulator according to claim 2, 4 or 6, characterized in that: The operating fluid is hydraulic oil.

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