Piston type energy accumulator

Abstract

The utility model relates to a piston type energy accumulator which is provided with an energy accumulator shell (10), a separating piston (12) can be guided in the energy accumulator shell in a longitudinal displacement mode, the piston type energy accumulator is provided with a damping piston (18) with a check valve (20), and the damping piston can move into a fluid connector (24) in the energy accumulator shell under the condition that a throttling gap (22) is formed. The throttle gap is a cylindrical annular space which is formed by adjacent walls (28, 32) of the energy store housing and the damping piston, and the check valve has a valve ball (36) which is loaded by the energy store, a damping valve (68) which, in the closed position thereof, blocks a fluid path between the fluid connection and a piston fluid chamber (38) located between the separating piston and the accumulator housing and, in the open position thereof, releases the fluid path, the damping valve (68) being located in the region of an internal thread (26) of the fluid connection and having a longitudinally displaceable valve plate (70), an orifice (72) is introduced into the valve plate coaxially to a longitudinal axis (60) of the piston accumulator.

Description

[0001] This divisional application is based on a Chinese patent application with international application number PCT / EP2022 / 086999, Chinese application number 202290000841.0, filing date December 20, 2022, and utility model name "Piston accumulator". Technical Field

[0002] The utility model relates to a piston accumulator having an accumulator housing in which a separating piston is guided longitudinally displaceably, the separating piston separating two fluid chambers from each other, in particular separating a fluid chamber having a working gas from another fluid chamber having a liquid, such as hydraulic oil, and the separating piston having a damping piston with a check valve, the damping piston being movable into a fluid connection in the accumulator housing with a throttling gap formed. Background Art

[0003] A piston-cylinder unit of the same type with damping of the piston end position is known from EP0286777A2, the piston-cylinder unit having a damping piston protruding on the end face of the piston, the damping piston being movable into a damping chamber provided at the opposite cylinder end with a damping gap tapering conically in the direction of the fluid connection and having a flow path provided for introducing the return lift movement of the piston, the flow path leading from the fluid connection for pressure oil around the damping gap to a pressure chamber adjacent to the main piston face of the piston in the accumulator housing and including a check valve. This flow path controllable by the check valve extends between an inlet opening at the front end of the damping piston constructed as a hollow sleeve inside the piston and a port in the form of a transverse passage leading from the inner cavity of the sleeve to the outside. The check valve used in this regard has a solid valve plate controllable by an energy storage device in the form of a compression spring, the valve plate controlling a large opening cross-section in the damping piston, which results in a leak in the closed position and eddies during flow through when the valve is open. In addition, due to the inertial characteristics of the valve plate, rapid opening and closing processes are excluded. Summary of the Utility Model

[0004] Therefore, starting from the prior art, the task of the present utility model is to further improve the known solution so as to provide a piston accumulator which, in addition to having improved response characteristics when fluid flows into or out of the hydraulic accumulator, also has improved end position damping for the separating piston.

[0005] To this end, the present utility model provides a piston accumulator. The piston accumulator has an accumulator housing, and a separating piston is guided longitudinally displaceably in the accumulator housing. The separating piston separates two fluid chambers from each other, and the separating piston has a damping piston with a check valve. The damping piston can be moved into a fluid connection in the accumulator housing with a throttling gap formed. The throttling gap is a cylindrical annular space formed by adjacent wall portions of the accumulator housing and the damping piston. The check valve has a valve ball loaded by the accumulator. The valve ball blocks the fluid path between the fluid connection and the piston fluid chamber located between the separating piston and the accumulator housing in its closed position and releases this fluid path in its open position. Wherein, a damping valve is located in the region of the internal thread of the fluid connection. The damping valve has a longitudinally displaceable valve plate, and a throttling orifice is introduced into the valve plate coaxially with the longitudinal axis of the piston accumulator.

[0006] By means of the throttling gap being a cylindrical annular space formed by adjacent wall portions of the accumulator housing and the damping piston, and the check valve having a valve ball loaded by the accumulator, the valve ball blocks the fluid path between the fluid connection and the piston fluid chamber located between the separating piston and the accumulator housing in its closed position and releases this fluid path in its open position, a constant throttling gap width is achieved over the entire engagement length of the damping piston in the fluid connection. This achieves significantly improved end position damping. Since there is no need to consider the continuously changing gap geometry with tapered sections as shown in the prior art, the engagement length of the damping piston in the fluid connection can be selected to be very long within a pre-given range (depending on the geometry to be maintained of the hydraulic accumulator), so as to achieve significantly improved piston end position damping in combination with a constant gap size over the entire engagement length. In addition, the valve ball of the check valve can achieve an improved valve seat geometry, which has improved sealing in the closed position and reduced eddy currents when flowing through in the open position. Moreover, due to the low inertia of the correspondingly small-sized valve ball or closing ball, the fluid flows that occur correspondingly during the loading and unloading of the hydraulic accumulator can be controlled quickly, continuously and reliably. There is no similar solution in the prior art.

[0007] In a preferred embodiment of the piston accumulator according to the present utility model, it is provided that the damping piston is formed by a hollow cylinder, and the hollow cylinder establishes a fluid path between the fluid connection and the check valve at least in one of its damping positions by means of its hollow cylindrical through portion. Here, the diameter of the hollow cylinder in the damping piston is substantially equal to the diameter of the valve closing ball, so that when the accumulator is loaded with a fluid (such as hydraulic oil), the valve ball is faced with the flow in the center and can thus be lifted from its valve seat in the associated valve housing without hindrance.

[0008] In another preferred embodiment of the piston accumulator according to the present invention, it is provided that, when viewed in the direction of the piston fluid chamber, the damping piston transitions into a widened portion with an annular surface in the case of forming a shoulder, and the annular surface forms an annular gap when the separating piston abuts against a component (such as a housing cover) of the accumulator housing, and the gap size of the annular gap is larger than the gap size of the throttle gap. In this way, until the separating piston completely abuts against the adjacent upper side of the housing cover in its lower displacement position when unloading the accumulator, the movement of the separating piston is further damped by the annular gap, so that the throttle gap and the annular gap jointly bear the damping of the movement of the separating piston.

[0009] In another preferred embodiment of the piston accumulator according to the present invention, it is provided that the annular surface is part of an insert body, the insert body houses a check valve and is preferably fixed in the receiving portion of the separating piston by means of a clamping ring between the insert body and the separating piston. Since the check valve is an integral part of the insert body, the damping device can be connected to the separating piston as a whole from the center point, especially from the lower side of the separating piston, which is very assembly-friendly and involves few working steps. In this regard, the piston accumulator solution according to the present invention can also be manufactured cost-effectively.

[0010] In another preferred embodiment of the piston accumulator according to the present invention, it is provided that the check valve is designed as a valve cartridge (Ventilpatrone), its valve housing is screwed into the insert body and the valve ball is guided in the valve housing by a reservoir, preferably in the form of a compression spring, which continuously loads it. The valve cartridge is common on the market and can in particular be adapted in terms of the connection geometry to different hydraulic accumulator sizes, which contributes to a functionally reliable and cost-effective construction of the overall end position damping.

[0011] Here, preferably, the valve housing has at least one first transverse channel, which can be controlled by the valve ball of the check valve and guided in the direction of a corresponding second transverse channel in the insert body. Here, the valve housing preferably has a notch, preferably in the form of a valve annular space, on the outer peripheral side, the corresponding first transverse channel of the valve housing leads into the notch from one side and the corresponding second transverse channel in the insert body leads into the notch from the opposite other side. In this way, an overall flow guidance (Gesamtströmungsführung) is achieved together with the insert body, and by deflecting the vertically flowing fluid flow by approximately 90° during loading of the accumulator, the fluid flow is deflected into the transverse guide portion in the direction of the piston fluid chamber, which is particularly advantageous in terms of energy and directly enables timely control of the separating piston during the loading process.

[0012] In another preferred embodiment of the piston accumulator according to the invention, it is provided that the separating piston defines a cavity-like recess on its side facing the fluid connection, the cavity-like recess opens into the bevel in the direction of the clamping ring, and the bore axis of the corresponding second transverse channel in the insert body is aligned with the wall of the separating piston that at least partially defines the recess in the separating piston and the bevel opens into the recess at the wall. By means of the preferably circumferential bevel, the clamping ring for fixing the insert body can be reliably positioned in the separating piston and the bevel can also serve as an oncoming flow aid for directly converting the transverse force of the fluid flow into a lifting movement of the separating piston within the scope of the accumulator charging process.

[0013] As already explained, it is particularly preferably provided that the axial length of the damping piston is greater than the corresponding height of the piston fluid chamber in the separating piston, which is at least partially penetrated by the insert body. In practical tests, it has been shown that with this length-height design, particularly good damping characteristics are produced during the discharge process of the accumulator and in the opposite direction of charging the accumulator, the separating piston is displaced unhindered in the direction of the fluid chamber containing the working gas and is prestressed in the process.

[0014] The utility model also relates to a method for operating a piston accumulator, which comprises the following method steps:

[0015] - when unloading the piston accumulator, the volume flow is throttled by forming a hollow cylindrical throttling gap between the damping piston and parts of the accumulator housing,

[0016] - When the piston accumulator is charged, the check valve integrated in the separating piston is opened by the valve ball charged by the accumulator, the throttling gap is bypassed due to the pressure difference generated in the throttling gap, and this causes

[0017] Applying fluid pressure to the entire free piston cross section in order to displace the dividing piston directly in the direction of the further fluid chamber containing the working gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The piston accumulator according to the present invention will be described in more detail below with reference to the accompanying drawings and with the aid of embodiments. In the accompanying drawings:

[0019] The only Figure 1 The lower part of an otherwise conventional piston accumulator, as shown by way of example in EP 0 286 777 A2, is shown in longitudinal section. DETAILED DESCRIPTION

[0020] Figure 1Shows the lower part of a piston accumulator, which has a hollow cylindrical wall part 8 of an accumulator housing integrally marked with 10. A separating piston 12 is guided longitudinally displaceably in the accumulator housing. The separating piston separates two fluid chambers 14, 16 from each other, in particular separates a fluid chamber 14 with a working gas (such as nitrogen) from another fluid chamber 16 with a liquid (such as hydraulic oil). In addition, the separating piston 12 has a damping piston 18 with a check valve 20 at the end of its free end face. The damping piston 18 can be moved into a fluid connection 24 in the accumulator housing 10 with a throttling gap 22 formed, Figure 1 Shows the maximum lowest position of the separating piston 12 in the accumulator housing 10 (in the case where the fluid flow in the direction from the fluid chamber 16 side towards the fluid connection 24 is subject to maximum throttling (Androsselung)). The position of the separating piston 12 shown in Figure 1 corresponds to the maximum unloading condition of the hydraulic accumulator as a whole. Through an internal thread 26 in the fluid connection 24, the piston accumulator can generally be connected to a hydraulic circuit of a common structural type (not shown) by means of a pipe (not shown).

[0021] As also derived from Figure 1 it, the throttling gap 22 is a cylindrical annular space or a fluid-filled hollow cylinder, which is formed by an adjacent wall part 28 of the accumulator housing 10 in the form of a housing cover 30 and an oppositely adjacent wall part 32 of the damping piston 18. The housing cover 30 is screwed into the hollow cylindrical wall part 8 of the accumulator housing on the bottom side as a part of the accumulator housing 10 and is sealed relative to the rest of the accumulator housing 10 by an annular seal (not shown in detail) in an annular groove 31. The separating piston 12 has two annular grooves 33 on its outer peripheral side for accommodating sealing rings and guide bands (not shown in detail), and only the upper annular groove is marked with 33 among the two annular grooves. The check valve 20 has a valve ball 36 continuously loaded by an energy storage device in the form of a compression spring 34. The valve ball blocks the fluid path between the fluid connection 24 and a piston fluid chamber 38 located between the separating piston 12 and the accumulator housing 10 or the housing cover 30 in its closed position shown in Figure 1 and releases this fluid path in the open position against the action of the compression spring 34. The piston fluid chamber 38 is formed by a cavity-like recess on the lower side of the separating piston 12 in the current case, and the cavity-like recess is surrounded by the wall part of the separating piston 12 at the height of the sealing ring system in the annular groove 33 on the outer peripheral side.

[0022] As also derived from Figure 1 it further, the damping piston 18 is formed by a hollow cylinder, which at least in one of its damping positions (in Figure 1in the fully damped position) establishes a fluid path between the fluid connection 24 and the check valve 20 and its valve ball 36 via its hollow cylindrical through-passage 40. Viewed in the direction of the piston fluid chamber 38, the damping piston 18, which is reduced in diameter, transitions into a widened portion that is enlarged in diameter compared thereto and has an annular surface 44. According to the illustration in accordance with Figure 1 the annular surface forms an annular gap 46 in the case where the separating piston 12 abuts against a component in the form of the housing cover 30 of the accumulator housing 10, and the gap size of the annular gap is preferably selected to be larger than the free gap size of the throttle gap 22.

[0023] The annular surface 44 is part of an insert 48, which as a whole accommodates the check valve 20 and is held in the hollow cylindrical receiving portion 50 of the separating piston 12 by means of a clamping ring 52 between the insert 48 and the separating piston 12. The check valve 20 is designed as a valve cartridge in this regard, and its valve housing 54 is screwed into the insert 48 using an internal hexagon screw 55, and according to the illustration in accordance with Figure 1In the illustrated view, the valve ball 36 is held sealingly in its closed position on the valve seat 56 in the valve housing 54 by the action of the compression spring 34. The valve housing 54 has a first transverse passage 58 diametrically opposite each other with respect to the longitudinal axis 60 of the hydraulic accumulator, and the first transverse passage is directly connected to the valve ball 36 and can be controlled by the valve ball. Instead of a pair of first transverse passages 58, a different number of first transverse passages 58 can also be provided, in particular only a single first transverse passage 58 can be provided. The corresponding first transverse passage 58 leads in the valve housing 54 in the direction of an assignable further second transverse passage 62 in the insert 48. Between the mutually assigned pairs of the first transverse passage 58 and the second transverse passage 62, the valve housing 54 has a notch 64 in the form of a preferably valve annular space on the outer peripheral side, and the corresponding first transverse passage 58 of the valve housing 54 leads into the notch from one side, and the corresponding assigned second transverse passage 62 in the insert 58 leads into the notch from the opposite other side. The separating piston 12 defines a cavity-shaped recess on the side facing the fluid connection 24 as part of the piston fluid chamber 38, and the cavity-shaped recess leads into an inclined portion 66 in the separating piston 12 in the direction of the clamping ring 52, and the inclined portion 66 extends upward in a conical shape in the direction of the longitudinal axis 60. Here, the hole axis of the corresponding second transverse passage 62 in the insert 48 is aligned with the upper boundary wall of the recess in the separating piston 12, and the inclined portion 66 extending circumferentially in the separating piston 12 leads into the upper boundary wall. It is particularly important for the piston accumulator solution according to the present invention that as long as the damping piston engages with the components of the fluid connection 24, the axial length of the damping piston 18 is at least greater than the corresponding height of the piston fluid chamber 38 formed by the recess in the separating piston 12, and the corresponding height is at least partially penetrated by the insert 46 in this regard.

[0024] Figure 1 The piston accumulator shown in can then be operated with the equipment according to the present invention as follows:

[0025] - When unloading the piston accumulator, the volumetric flow rate is throttled by forming a hollow cylindrical throttling gap 22 between the damping piston 18 and the components of the accumulator housing 10, and the fluid is expelled from the fluid chamber 16 through the throttling gap 22 in the direction of the fluid connection 24 kept at zero pressure by the relevant downward movement of the separating piston 12. Here, further throttling is achieved through the annular gap 46 between the insert 48 and the adjacent wall upper side of the housing cover 30;

[0026] - When loading the piston accumulator, the check valve 20 integrated in the separating piston 12 is opened by using the valve ball 36 loaded by the compression spring 34, and the throttle gaps 22, 46 are bypassed due to the pressure difference generated especially in the throttle gap 22. Due to the fluid pressure present in the fluid connection 24, the check valve 20 is opened and the fluid flows through the hollow cylindrical through portion 40 and through the interior of the valve housing 54 in the direction of the first transverse channel 58 and the second transverse channel 62, and the first transverse channel and the second transverse channel are flow - guidingly connected to the notch 64 of the valve housing 54. In this way, the fluid reaches the piston fluid chamber 38 under pressure via the fluid connection 24, and looking in the viewing direction towards Figure 1 , the separating piston 12 is lifted upwards. In the case of further displacement movement against the action of the working gas in the fluid chamber 14, the fluid volume on the liquid side increases as the fluid chamber 16 enlarges. This subsequently causes

[0027] - Loading the fluid pressure onto the entire free piston cross - section to displace the separating piston 12 directly in the direction of the other fluid chamber 14 with the working gas. Once the damping piston 18 completely releases the fluid through - portion 24 due to the displacement movement of the separating piston 12 in the direction of the fluid chamber 14, more fluid flows from the hydraulic circuit towards the fluid chamber 16. In this operating position, the hydraulic accumulator is then used again for the described unloading process.

[0028] The damping valve, marked as a whole with 68, is located in the region of the internal thread 26 of the fluid connection 24. The damping valve has a longitudinally displaceable valve plate 70, and the throttle orifice 72 is introduced coaxially with the longitudinal axis 60 of the hydraulic accumulator into the valve plate. The valve plate 70 is received in the valve housing 74, which is preferably designed as a tripod, and the valve housing is screwed flush with the internal thread 26 into the fluid connection 24. Since there is a corresponding fluid supply 76 between the legs of the valve housing 74, in the shown position for loading the accumulator via the inflow portion 78 on the bottom side in the valve housing 74, for the loading process of the accumulator, the fluid can flow relatively undisturbed from the hydraulic working circuit via the fluid connection 24 in the direction of the fluid chamber 16 at a pre - given pressure when the check valve 20 is open. In the opposite direction, that is, when the accumulator is unloaded, the valve plate 70 is displaced from its upper displacement position shown in Figure 1 to the lower closed position, in which the valve plate 70 abuts against the inner side of the valve housing 74 and the fluid through - portion is thus only provided by the throttle orifice 72 in the valve plate 70, so that in addition to the already described throttling measures 22, 46, the throttling of the fluid flow is also achieved by the damping valve 68. More detailed details about the function of the damping valve can be obtained, for example, from DE10337744B3.

Claims

1. Piston accumulator, said piston accumulator having an accumulator housing (10), a separating piston (12) being guided longitudinally displaceably in said accumulator housing, said separating piston separating two fluid chambers from each other, and said separating piston having a damping piston (18) with a check valve (20), said damping piston being movable into a fluid connection (24) in the accumulator housing (10) with a throttling gap (22) formed, said throttling gap (22) being a cylindrical annular space formed by adjacent wall portions (28, 32) of the accumulator housing (10) and the damping piston (18), said check valve (20) having a valve ball (36) loaded by an energy storage device, said valve ball blocking the fluid path between the fluid connection (24) and the piston fluid chamber (38) located between the separating piston (12) and the accumulator housing (10) in its closed position and releasing said fluid path in its open position, characterized in that, The damping valve (68) is located in the region of the internal thread (26) of the fluid connection (24). The damping valve has a longitudinally displaceable valve plate (70), and a throttle orifice (72) is introduced into the valve plate coaxially with the longitudinal axis (60) of the piston accumulator.

2. The piston accumulator according to claim 1, characterized in that, The damping piston (18) is formed by a hollow cylinder which, in at least one of its damping positions, establishes a fluid path between the fluid connection (24) and the check valve (20) by means of its hollow cylindrical through-passage (40).

3. The piston accumulator according to claim 1 or 2, characterized in that, Viewed in the direction of the piston fluid chamber (38), the damping piston (18) transitions into a widened portion having an annular face (44) in the case of forming a shoulder (42). The annular face constructs an annular gap (46) when the separating piston (12) abuts against a component of the accumulator housing, and the gap size of the annular gap is larger than the gap size of the throttle gap (22).

4. The piston accumulator according to claim 3, characterized in that, The annular face (44) is part of an insert (48) which houses the check valve (20) and is fixed in the receiving portion (50) of the separating piston (12).

5. The piston accumulator according to claim 4, wherein The check valve (20) is designed as a valve cartridge, whose valve housing (54) is screwed into the insert (48), and the valve ball (36) is guided in the valve housing (54) by a reservoir in the form of a compression spring (34) with continuous loading.

6. The piston accumulator according to claim 5, characterized in that, The valve housing (54) has at least one first transverse channel (58) which can be controlled by the valve ball (36) of the check valve (20) and is guided in the direction of an assigned second transverse channel (62) in the insert (48).

7. The piston accumulator according to claim 6, characterized in that, The valve housing (54) has a notch (64) on its outer peripheral side. The corresponding first transverse channel (58) of the valve housing (54) leads into the notch from one side, and the corresponding assigned second transverse channel (62) in the insert (48) leads into the notch from the opposite other side.

8. The piston accumulator according to claim 6 or 7, characterized in that, The separating piston (12) defines a cavity-shaped recess on its side facing the fluid connection (24) as part of the piston fluid chamber (38). The cavity-shaped recess leads into an inclined portion (66) in the separating piston (12) in the direction of the clamping ring (52), and the hole axis of the corresponding second transverse channel (62) in the insert (48) is aligned with the following wall of the separating piston (12), which wall at least partially defines the recess in the separating piston (12) and into which the inclined portion (66) leads.

9. The piston accumulator according to claim 1 or 2, characterized in that, The axial length of the damping piston (18) is greater than the corresponding height of the piston fluid chamber (38) in the separating piston (12), and the corresponding height is at least partially penetrated by the insert (48).

10. The piston accumulator according to claim 1, characterized in that, The separating piston separates the fluid chamber with the working gas from another fluid chamber with the liquid.

11. The piston accumulator according to claim 10, characterized in that, The liquid is hydraulic oil.

12. The piston accumulator according to claim 3, wherein, The annular face constructs the annular gap (46) when the separating piston (12) abuts against the housing cover (30).

13. The piston accumulator according to claim 4, characterized in that, The insert is fixed in the receiving portion (50) of the separating piston (12) by means of a clamping ring (52) between the insert (48) and the separating piston (12).

14. The piston accumulator according to claim 7, wherein, The notch is a notch in the form of a valve annular space.

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